Author(s) ID,Title,Year,DOI,Link,Abstract
"56462887500;35069282600;57203596463;10139397300;","Volcano and Ship Tracks Indicate Excessive Aerosol-Induced Cloud Water Increases in a Climate Model",2017,"10.1002/2017GL075280","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039152778&doi=10.1002%2f2017GL075280&partnerID=40&md5=9f9971db1e185af314d668ef84e12caf","Aerosol-cloud interaction is the most uncertain mechanism of anthropogenic radiative forcing of Earth's climate, and aerosol-induced cloud water changes are particularly poorly constrained in climate models. By combining satellite retrievals of volcano and ship tracks in stratocumulus clouds, we compile a unique observational data set and confirm that liquid water path (LWP) responses to aerosols are bidirectional, and on average the increases in LWP are closely compensated by the decreases. Moreover, the meteorological parameters controlling the LWP responses are strikingly similar between the volcano and ship tracks. In stark contrast to observations, there are substantial unidirectional increases in LWP in the Hadley Centre climate model, because the model accounts only for the decreased precipitation efficiency and not for the enhanced entrainment drying. If the LWP increases in the model were compensated by the decreases as the observations suggest, its indirect aerosol radiative forcing in stratocumulus regions would decrease by 45%. ©2017. American Geophysical Union. All Rights Reserved."
"57194876603;55803016100;30967646900;57203030873;","Do Southern Ocean Cloud Feedbacks Matter for 21st Century Warming?",2017,"10.1002/2017GL076339","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038623422&doi=10.1002%2f2017GL076339&partnerID=40&md5=c2852a628d0e1eb440f4fb72abd776b4","Cloud phase improvements in a state-of-the-art climate model produce a large 1.5 K increase in equilibrium climate sensitivity (ECS, the surface warming in response to instantaneously doubled CO2) via extratropical shortwave cloud feedbacks. Here we show that the same model improvements produce only a small surface warming increase in a realistic 21st century emissions scenario. The small 21st century warming increase is attributed to extratropical ocean heat uptake. Southern Ocean mean-state circulation takes up heat while a slowdown in North Atlantic circulation acts as a feedback to slow surface warming. Persistent heat uptake by extratropical oceans implies that extratropical cloud biases may not be as important to 21st century warming as biases in other regions. Observational constraints on cloud phase and shortwave radiation that produce a large ECS increase do not imply large changes in 21st century warming. ©2017. American Geophysical Union. All Rights Reserved."
"7401836526;55558939800;57204297370;36097134700;","Earth System Modeling 2.0: A Blueprint for Models That Learn From Observations and Targeted High-Resolution Simulations",2017,"10.1002/2017GL076101","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039757485&doi=10.1002%2f2017GL076101&partnerID=40&md5=4e56b653854b8b320621ee6b843ca5a1","Climate projections continue to be marred by large uncertainties, which originate in processes that need to be parameterized, such as clouds, convection, and ecosystems. But rapid progress is now within reach. New computational tools and methods from data assimilation and machine learning make it possible to integrate global observations and local high-resolution simulations in an Earth system model (ESM) that systematically learns from both and quantifies uncertainties. Here we propose a blueprint for such an ESM. We outline how parameterization schemes can learn from global observations and targeted high-resolution simulations, for example, of clouds and convection, through matching low-order statistics between ESMs, observations, and high-resolution simulations. We illustrate learning algorithms for ESMs with a simple dynamical system that shares characteristics of the climate system; and we discuss the opportunities the proposed framework presents and the challenges that remain to realize it. ©2017. American Geophysical Union. All Rights Reserved."
"57195219129;7101959253;55087038900;","The Diurnal Cycle of Clouds and Precipitation at the ARM SGP Site: An Atmospheric State-Based Analysis and Error Decomposition of a Multiscale Modeling Framework Simulation",2017,"10.1002/2017JD027542","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040734102&doi=10.1002%2f2017JD027542&partnerID=40&md5=798e1bab261e2dae06b63c37a1a02030","Long-term reflectivity data collected by a millimeter cloud radar at the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site are used to examine the diurnal cycle of clouds and precipitation and are compared with the diurnal cycle simulated by a Multiscale Modeling Framework (MMF) climate model. The study uses a set of atmospheric states that were created specifically for the SGP and for the purpose of investigating under what synoptic conditions models compare well with observations on a statistical basis (rather than using case studies or seasonal or longer time scale averaging). Differences in the annual mean diurnal cycle between observations and the MMF are decomposed into differences due to the relative frequency of states, the daily mean vertical profile of hydrometeor occurrence, and the (normalized) diurnal variation of hydrometeors in each state. Here the hydrometeors are classified as cloud or precipitation based solely on the reflectivity observed by a millimeter radar or generated by a radar simulator. The results show that the MMF does not capture the diurnal variation of low clouds well in any of the states but does a reasonable job capturing the diurnal variations of high clouds and precipitation in some states. In particular, the diurnal variations in states that occur during summer are reasonably captured by the MMF, while the diurnal variations in states that occur during the transition seasons (spring and fall) are not well captured. Overall, the errors in the annual composite are due primarily to errors in the daily mean of hydrometeor occurrence (rather than diurnal variations), but errors in the state frequency (that is, the distribution of weather states in the model) also play a significant role. ©2017. The Authors."
"56054435300;55720588700;55790781000;36196693000;55720539800;7004697990;7404395984;","The Impact of Cross-track Infrared Sounder (CrIS) Cloud-Cleared Radiances on Hurricane Joaquin (2015) and Matthew (2016) Forecasts",2017,"10.1002/2017JD027515","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038815561&doi=10.1002%2f2017JD027515&partnerID=40&md5=ab52111b5e53941189107244687b067a","Hyperspectral infrared (IR) sounders provide high vertical resolution atmospheric sounding information that can improve the forecast skill in numerical weather prediction. Commonly, only clear radiances are assimilated, because IR sounder observations are highly affected by clouds. A cloud-clearing (CC) technique, which removes the cloud effects from an IR cloudy field of view (FOV) and derives the cloud-cleared radiances (CCRs) or clear-sky equivalent radiances, can be an alternative yet effective way to take advantage of the thermodynamic information from cloudy skies in data assimilation. This study develops a Visible Infrared Imaging Radiometer Suite (VIIRS)-based CC method for deriving Cross-track Infrared Sounder (CrIS) CCRs under partially cloudy conditions. Due to the lack of absorption bands on VIIRS, two important quality control steps are implemented in the CC process. Validation using VIIRS clear radiances indicates that the CC method can effectively obtain the CrIS CCRs for FOVs with partial cloud cover. To compare the impacts from assimilation of CrIS original radiances and CCRs, three experiments are carried out on two storm cases, Hurricane Joaquin (2015) and Hurricane Matthew (2016), using Gridpoint Statistical Interpolation assimilation system and Weather Research and Forecasting-Advanced Research Version models. At the analysis time, more CrIS observations are assimilated when using CrIS CCRs than with CrIS original radiances. Comparing temperature, specific humidity, and U/V winds with radiosondes indicates that the data impacts are growing larger with longer time forecasts (beyond 72 h forecast). Hurricane track forecasts also show improvements from the assimilation of CrIS CCRs due to better weather system forecasts. The impacts of CCRs on intensity are basically neutral with mixed positive and negative results. ©2017. American Geophysical Union. All Rights Reserved."
"10243650000;10241250100;55686667100;55537426400;10241462700;7003420726;35580303100;57200122928;57200123725;57208483843;36701462300;6603370049;7102857642;","Effectiveness and limitations of parameter tuning in reducing biases of top-of-atmosphere radiation and clouds in MIROC version 5",2017,"10.5194/gmd-10-4647-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039761995&doi=10.5194%2fgmd-10-4647-2017&partnerID=40&md5=981c8a5fe054dc30a54be81b5a708329","This study discusses how much of the biases in top-of-atmosphere (TOA) radiation and clouds can be removed by parameter tuning in the present-day simulation of a climate model in the Coupled Model Inter-comparison Project phase 5 (CMIP5) generation. We used output of a perturbed parameter ensemble (PPE) experiment conducted with an atmosphere-ocean general circulation model (AOGCM) without flux adjustment. The Model for Interdisciplinary Research on Climate version 5 (MIROC5) was used for the PPE experiment. Output of the PPE was compared with satellite observation data to evaluate the model biases and the parametric uncertainty of the biases with respect to TOA radiation and clouds. The results indicate that removing or changing the sign of the biases by parameter tuning alone is difficult. In particular, the cooling bias of the shortwave cloud radiative effect at low latitudes could not be removed, neither in the zonal mean nor at each latitude-longitude grid point. The bias was related to the overestimation of both cloud amount and cloud optical thickness, which could not be removed by the parameter tuning either. However, they could be alleviated by tuning parameters such as the maximum cumulus updraft velocity at the cloud base. On the other hand, the bias of the shortwave cloud radiative effect in the Arctic was sensitive to parameter tuning. It could be removed by tuning such parameters as albedo of ice and snow both in the zonal mean and at each grid point. The obtained results illustrate the benefit of PPE experiments which provide useful information regarding effectiveness and limitations of parameter tuning. Implementing a shallow convection parameterization is suggested as a potential measure to alleviate the biases in radiation and clouds. © Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License."
"57200005970;16403404400;53878006900;","Climate engineering and the ocean: Effects on biogeochemistry and primary production",2017,"10.5194/bg-14-5675-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038634392&doi=10.5194%2fbg-14-5675-2017&partnerID=40&md5=c411b07c1a82ca9c7adcfea517bfb7d3","Here we use an Earth system model with interactive biogeochemistry to project future ocean biogeochemistry impacts from the large-scale deployment of three different radiation management (RM) climate engineering (also known as geoengineering) methods: stratospheric aerosol injection (SAI), marine sky brightening (MSB), and cirrus cloud thinning (CCT). We apply RM such that the change in radiative forcing in the RCP8.5 emission scenario is reduced to the change in radiative forcing in the RCP4.5 scenario. The resulting global mean sea surface temperatures in the RM experiments are comparable to those in RCP4.5, but there are regional differences. The forcing from MSB, for example, is applied over the oceans, so the cooling of the ocean is in some regions stronger for this method of RM than for the others. Changes in ocean net primary production (NPP) are much more variable, but SAI and MSB give a global decrease comparable to RCP4.5 (ĝ1/4ĝ€6ĝ€% in 2100 relative to 1971-2000), while CCT gives a much smaller global decrease of ĝ1/4ĝ€3ĝ€%. Depending on the RM methods, the spatially inhomogeneous changes in ocean NPP are related to the simulated spatial change in the NPP drivers (incoming radiation, temperature, availability of nutrients, and phytoplankton biomass) but mostly dominated by the circulation changes. In general, the SAI- and MSB-induced changes are largest in the low latitudes, while the CCT-induced changes tend to be the weakest of the three. The results of this work underscore the complexity of climate impacts on NPP and highlight the fact that changes are driven by an integrated effect of multiple environmental drivers, which all change in different ways. These results stress the uncertain changes to ocean productivity in the future and advocate caution at any deliberate attempt at large-scale perturbation of the Earth system. © Author(s) 2017."
"56720338300;56011382000;56737077200;7202408584;16174796300;6602661960;7006287865;7004741554;15835359300;6701620591;7005456532;","A new method for estimating UV fluxes at ground level in cloud-free conditions",2017,"10.5194/amt-10-4965-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038633074&doi=10.5194%2famt-10-4965-2017&partnerID=40&md5=7cbf9ef15ffb5ffcf518de433cbb2bec","A new method has been developed to estimate the global and direct solar irradiance in the UV-A and UV-B at ground level in cloud-free conditions. It is based on a resampling technique applied to the results of the κ-distribution method and the correlated-κ approximation of Kato et al. (1999) over the UV band. Its inputs are the aerosol properties and total column ozone that are produced by the Copernicus Atmosphere Monitoring Service (CAMS). The estimates from this new method have been compared to instantaneous measurements of global UV irradiances made in cloud-free conditions at five stations at high latitudes in various climates. For the UV-A irradiance, the bias ranges between-'0.8-Wm-2 (-'3-% of the mean of all data) and-'0.2-Wm-2 (-'1-%). The root mean square error (RMSE) ranges from 1.1-Wm-2 (6-%) to 1.9-Wm-2 (9-%). The coefficient of determination <i>R</i>2 is greater than 0.98. The bias for UV-B is between-'0.04-Wm-2 (-'4-%) and 0.08-Wm-2 (+13-%) and the RMSE is 0.1-Wm-2 (between 12 and 18-%). <i>R</i>2 ranges between 0.97 and 0.99. This work demonstrates the quality of the proposed method combined with the CAMS products. Improvements, especially in the modeling of the reflectivity of the Earth's surface in the UV region, are necessary prior to its inclusion into an operational tool."
"57192202375;57198282163;57191589479;7006747377;54788178800;56189039500;57203233100;57214536094;23866122100;","Cyclone-induced surface ozone and HDO depletion in the Arctic",2017,"10.5194/acp-17-14955-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038618642&doi=10.5194%2facp-17-14955-2017&partnerID=40&md5=a63ed52057ebe3324bb46408e7f5e5bf","Ground-based, satellite, and reanalysis datasets were used to identify two similar cyclone-induced surface ozone depletion events at Eureka, Canada (80.1 N, 86.4 W), in March 2007 and April 2011. These two events were coincident with observations of hydrogen deuterium oxide (HDO) depletion, indicating that condensation and sublimation occurred during the transport of the ozone-depleted air masses. Ice clouds (vapour and crystals) and aerosols were detected by lidar and radar when the ozone- and HDO-depleted air masses arrived over Eureka. For the 2007 event, an ice cloud layer was coincident with an aloft ozone depletion layer at 870g m altitude on 2-3 March, indicating this ice cloud layer contained bromine-enriched blowing-snow particles. Over the following 3 days, a shallow surface ozone depletion event (ODE) was observed at Eureka after the precipitation of bromine-enriched particles onto the local snowpack. A chemistry-climate model (UKCA) and a chemical transport model (pTOMCAT) were used to simulate the surface ozone depletion events. Incorporating the latest surface snow salinity data obtained for the Weddell Sea into the models resulted in improved agreement between the modelled and measured BrO concentrations above Eureka. MERRA-2 global reanalysis data and the FLEXPART particle dispersion model were used to study the link between the ozone and HDO depletion. In general, the modelled ozone and BrO showed good agreement with the ground-based observations; however, the modelled BrO and ozone in the near-surface layer are quite sensitive to the snow salinity. HDO depletion observed during these two blowing-snow ODEs was found to be weaker than pure Rayleigh fractionation. This work provides evidence of a blowing-snow sublimation process, which is a key step in producing bromine-enriched sea-salt aerosol. © Author(s) 2017."
"57205328130;6602806280;6603293321;","Comparative water relations of co-occurring trees in a mixed podocarp-broadleaf forest",2017,"10.1093/jpe/rty004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059573138&doi=10.1093%2fjpe%2frty004&partnerID=40&md5=bc22b98407565a334d0f02026e651d6c","Aims As extreme climatic events including droughts and heat waves become more common in a changing climate, tree mortality has increased across the globe. In order to determine whether certain species have a competitive advantage over others, we explored the water-relations and leaf-gas exchange of four co-occurring species in a forest in northern Aotearoa-New Zealand. We studied the ecologically and culturally significant foundation species, Agathis australis (a conifer), two additional conifers, Phyllocladus trichomanoides and Podocarpus totara and the angiosperm Knightia excelsa. Methods We measured sap flow, leaf-gas exchange and xylem water potentials of leaves and terminal branches with concurrent measures of micrometeorological data on days with very few clouds. We derived whole tree hydraulic conductance and instantaneous water-use efficiency (WUEi) at our remnant forest in west Auckland during February 2015 (southern hemisphere summer). Important Findings The four species behaved similarly in their diurnal curves of gas exchange and water potential. Rates of assimilation, stomatal conductance and WUEi were similar among trees of different species. Whole tree hydraulic conductance was also similar among species. These results indicate functional convergence in water relations, possibly driven by low nutrient soils at the site. Our results suggest that there is no species with a clear adaptive advantage over the others in the context of climate change. © The Author(s) 2017. Published by Oxford University Press on behalf of the Institute of Botany, Chinese Academy of Sciences and the Botanical Society of China. All rights reserved."
"56802284300;7003532404;6505811379;56162114200;7401472342;6602621536;7003279414;56273398400;","Measurements and modeling of surface-atmosphere exchange of microorganisms in Mediterranean grassland",2017,"10.5194/acp-17-14919-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038884972&doi=10.5194%2facp-17-14919-2017&partnerID=40&md5=1bb8b91c955cb8aaed59a7b6a4cf26e5","Microbial aerosols (mainly composed of bacterial and fungal cells) may constitute up to 74ĝ€% of the total aerosol volume. These biological aerosols are not only relevant to the dispersion of pathogens, but they also have geochemical implications. Some bacteria and fungi may, in fact, serve as cloud condensation or ice nuclei, potentially affecting cloud formation and precipitation and are active at higher temperatures compared to their inorganic counterparts. Simulations of the impact of microbial aerosols on climate are still hindered by the lack of information regarding their emissions from ground sources. This present work tackles this knowledge gap by (i) applying a rigorous micrometeorological approach to the estimation of microbial net fluxes above a Mediterranean grassland and (ii) developing a deterministic model (the PLAnET model) to estimate these emissions on the basis of a few meteorological parameters that are easy to obtain. The grassland is characterized by an abundance of positive net microbial fluxes and the model proves to be a promising tool capable of capturing the day-to-day variability in microbial fluxes with a relatively small bias and sufficient accuracy. PLAnET is still in its infancy and will benefit from future campaigns extending the available training dataset as well as the inclusion of ever more complex and critical phenomena triggering the emission of microbial aerosol (such as rainfall). The model itself is also adaptable as an emission module for dispersion and chemical transport models, allowing further exploration of the impact of land-cover-driven microbial aerosols on the atmosphere and climate. © Author(s) 2017."
"26434122800;7202824028;6701820543;15755536700;56433533700;","Supporting the detection and monitoring of volcanic clouds: A promising new application of Global Navigation Satellite System radio occultation",2017,"10.1016/j.asr.2017.06.039","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85023612878&doi=10.1016%2fj.asr.2017.06.039&partnerID=40&md5=caf6dad6d268e85e56f523beeb5a9c81","The altitude of volcanic clouds and the atmospheric thermal structure after volcanic eruptions are studied using Global Navigation Satellite System (GNSS) Radio Occultation (RO) profiles co-located with independent radiometer images of ash and sulfur dioxide plumes. We use geographically co-located RO profiles to detect the top altitude of volcanic clouds and to analyze their impact in terms of temperature change signatures. We obtained about 1300 RO profiles co-located with two representative eruptions (Puyehue 2011, Nabro 2011) and found that an anomaly technique recently developed for detecting convective cloud tops and studying the vertical thermal structure of deep convective systems can also be applied to volcanic clouds. Analyzing the atmospheric thermal structure after the eruptions, we found clear cooling signatures induced by volcanic cloud tops in the upper troposphere for the Puyehue case. For the Nabro case we detected a significant warming in the stratosphere which lasted for several months, indicating that the cloud reached the stratosphere. The results are encouraging for future large-scale use of RO data for supporting the monitoring of volcanic clouds and their impacts on weather and climate. © 2017 COSPAR"
"6701869931;23013020900;6603102974;55393706100;57191329421;55921755700;18634433100;8791306500;55866604100;7402287860;24329724000;35768617200;55917711400;7006960661;6601950693;","Stratospheric aerosol data records for the climate change initiative: Development, validation and application to chemistry-climate modelling",2017,"10.1016/j.rse.2017.06.002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022089612&doi=10.1016%2fj.rse.2017.06.002&partnerID=40&md5=2beac36e2d353a17de2e153766e0b1e6","This paper presents stratospheric aerosol climate records developed in the framework of the Aerosol_cci project, one of the 14 parallel projects from the ESA Climate Change Initiative. These data records were processed from a stratospheric aerosol dataset derived from the GOMOS experiment, using an inversion algorithm optimized for aerosol retrieval, called AerGOM. They provide a suite of aerosol parameters, such as the aerosol extinction coefficient at different wavelengths in the UV–visible range. The extinction record includes the total extinction as well as separate fields for liquid sulfate aerosols and polar stratospheric clouds (PSCs). Several additional fields (PSC flag, etc.) are also provided. The resulting stratospheric aerosol dataset, which spans the whole duration of the GOMOS mission (2002 − 2012), was validated using different reference datasets (lidar and balloon profiles). In the present paper, the emphasis is put on the extinction records. After a thorough analysis of the original AerGOM dataset, we describe the methodology used to construct the gridded CCI-GOMOS dataset and the resulting improvements on both the AerGOM algorithm and the binning procedure, in terms of spatio-temporal resolution, coverage and data quality. The extinction datasets were validated using lidar profiles from three ground-based stations (Mauna Loa, Garmisch-Partenkirchen, Dumont d'Urville). The median difference of the CCI-GOMOS (Level 3) extinction and ground-based lidar profiles is between ~ 15% and ~ 45% in the 16–21 km altitude range, depending on the considered site and aerosol type. The CCI-GOMOS dataset was subsequently used, together with a MIPAS SO2 time series, to update a volcanic eruption inventory published previously, thus providing a more comprehensive list of eruptions for the ENVISAT period (2002–2012). The number of quantified eruptions increases from 102 to 230 in the updated inventory. This new inventory was used to simulate the evolution of the global radiative forcing by application of the EMAC chemistry-climate model. Results of this simulation improve the agreement between modelled global radiative forcing of stratospheric aerosols at about 100 hPa compared to values estimated from observations. Medium eruptions like the ones of Soufriere Hills/Rabaul (2006), Sarychev (2009) and Nabro (2011) cause a forcing change from about − 0.1 W/m2 to − 0.2 W/m2. © 2017 The Authors"
"8718425100;13402933200;37089417300;9238068800;6603669676;57189359941;6602135031;6603549082;7006960661;8722794800;7004368198;57191170893;55917711400;22935251000;7003652536;57189361004;56597778200;9233141200;56206465300;6603341831;","Benchmarking CMIP5 models with a subset of ESA CCI Phase 2 data using the ESMValTool",2017,"10.1016/j.rse.2017.01.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009801618&doi=10.1016%2fj.rse.2017.01.007&partnerID=40&md5=9c34c1c73eeb9a877add0e607441245e","The Coupled Model Intercomparison Project (CMIP) is now moving into its sixth phase and aims at a more routine evaluation of the models as soon as the model output is published to the Earth System Grid Federation (ESGF). To meet this goal the Earth System Model Evaluation Tool (ESMValTool), a community diagnostics and performance metrics tool for the systematic evaluation of Earth system models (ESMs) in CMIP, has been developed and a first version (1.0) released as open source software in 2015. Here, an enhanced version of the ESMValTool is presented that exploits a subset of Essential Climate Variables (ECVs) from the European Space Agency's Climate Change Initiative (ESA CCI) Phase 2 and this version is used to demonstrate the value of the data for model evaluation. This subset includes consistent, long-term time series of ECVs obtained from harmonized, reprocessed products from different satellite instruments for sea surface temperature, sea ice, cloud, soil moisture, land cover, aerosol, ozone, and greenhouse gases. The ESA CCI data allow extending the calculation of performance metrics as summary statistics for some variables and add an important alternative data set in other cases where observations are already available. The provision of uncertainty estimates on a per grid basis for the ESA CCI data sets is used in a new extended version of the Taylor diagram and provides important additional information for a more objective evaluation of the models. In our analysis we place a specific focus on the comparability of model and satellite data both in time and space. The ESA CCI data are well suited for an evaluation of results from global climate models across ESM compartments as well as an analysis of long-term trends, variability and change in the context of a changing climate. The enhanced version of the ESMValTool is released as open source software and ready to support routine model evaluation in CMIP6 and at individual modeling centers. © 2017 Elsevier Inc."
"55754577000;6701820543;8903148000;55619312723;56183734900;25647484500;54969910100;","A review of low Earth orbit occultation using microwave and infrared-laser signals for monitoring the atmosphere and climate",2017,"10.1016/j.asr.2017.05.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020136989&doi=10.1016%2fj.asr.2017.05.011&partnerID=40&md5=f7ce26c799444807f73ffb7f2cddadf9","Global Navigation Satellite System radio occultation (GNSS RO, or in short GRO) has become a major method to observe the Earth's atmospheric thermodynamic state variables, i.e., pressure, temperature, and humidity as retrieved from refraction measurements using the GNSS radio wave signals. The GRO data products, such as bending angle and refractivity, are widely used for numerical weather prediction and global climate monitoring. Practically, in GRO, the temperature and humidity variables in the troposphere can only be retrieved separately from refractivity by co-using a priori humidity and/or temperature information. Fortunately, as an advanced technique beyond GRO, developed over the past two decades, future microwave occultation using centimeter and millimeter wave signals between low Earth orbit satellites (LEO-LEO microwave occultation, LMO), can exploit both the refraction and absorption of the signals to solve the temperature-humidity ambiguity in the troposphere. Thus, LMO promises to retrieve the pressure, temperature, and humidity profiles without auxiliary background information. Furthermore, it is anticipated that ozone profiles can be retrieved by absorption measurements near the 195 GHz ozone line, and line-of-sight wind speed in the upper stratosphere into the mesosphere. Liquid water and ice cloud variables as well as turbulence strength can be retrieved as by-products. Additionally, the novel concept of LEO-LEO infrared-laser occultation (LIO), using laser signals in the short-wave infrared band 2–2.5 µm between LEO satellites, has been designed to accurately observe key trace gas species for chemistry and climate (i.e., greenhouse gases H 2 O, CO 2 , CH 4 , N 2 O, O 3 , CO, including key isotopes), line-of-sight wind speed, and also profiles of cloud layers and aerosols as by-products. In 2010, a new occultation mission concept was proposed, named ACCURATE—climate benchmark profiling of greenhouse gases and thermodynamic variables and wind from space, which combines the highly synergetic LMO and LIO techniques into LEO-LEO microwave and infrared-laser occultation (LMIO) for monitoring the atmosphere and climate. Focusing on the LMO technique only, several other missions were proposed before, in particular ATOMMS (Active Temperature Ozone and Moisture Microwave Spectrometer) and ACE+ (Atmosphere and Climate Explorer-Plus). In this paper, a review of the LEO-LEO occultation techniques (LMO, LIO, and LMIO) in aspects of measurement principle, retrieval algorithms, atmospheric profiling performance and demonstration experiments is performed based on available literature. As part of the conclusions, discussions of outstanding issues, on-going activities, and recommendations for the future are given. © 2017 COSPAR"
"55422350900;8720083500;44561096100;7003286544;6701363731;26434299100;21834688500;","Enhanced surface ozone during the heat wave of 2013 in Yangtze River Delta region, China",2017,"10.1016/j.scitotenv.2017.03.056","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018754151&doi=10.1016%2fj.scitotenv.2017.03.056&partnerID=40&md5=423f34ccb56070991a6db81bb7a5c7c7","Under the background of global warming, occurrence of heat waves has increased in most part of Europe, Asia and Australia along with enhanced ozone level. In this paper, observational air temperature and surface ozone in the Yangtze River Delta (YRD) region of China during summer of 2013, and the regional chemistry-climate model (RegCM-CHEM4) were applied to explore the relationship between heat wave and elevated ground-level ozone. Observations indicated that YRD experienced severe heat waves with maximum temperature up to 41.1 °C, 6.1 °C higher than the definition of heat wave in China, and can last for as long as 27 days. Maximum ozone reached 160.5 ppb, exceeding the national air quality standard (secondary level) as 74.7 ppb. Moreover, ozone was found to increase at a rate of 4–5 ppb K− 1 within the temperature range of 28–38 °C, but decrease by a rate of − 1.3 ~ − 1.7 ppb K− 1 under extremely high temperature. A typical heat wave case (HW: 24/7–31/7) and non-heat wave case (NHW: 5/6–12/6) were selected to investigate the mechanism between heavy ozone and heat waves. It was found that chemical reactions play the most important role in ozone formation during HW days, which result in 12 ppb ozone enhancement compared to NHW days. Chemical formation of ozone can be influenced by several factors. During heat waves, a more stagnant condition, controlled by anti-cyclone with sink airflow, led to less water vapor in YRD from south and contributed to less cloud cover, which favored a strong solar radiation environment and ozone significantly increasing. High temperature also slightly promote the effect of vertical turbulence and horizontal advection, which beneficial to ozone remove, but the magnitude is much smaller than chemical effect. Our study suggests that the chemical reaction will potentially lead to substantial elevated ozone in a warmer climate, which should be taken into account in future ozone related issues. © 2017 Elsevier B.V."
"42361350100;7006041988;40461229800;7003591311;7004242319;57189999417;12803904100;","The observed influence of local anthropogenic pollution on northern Alaskan cloud properties",2017,"10.5194/acp-17-14709-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038248922&doi=10.5194%2facp-17-14709-2017&partnerID=40&md5=b8a83b6e4ba5cb8edab7bacb61604c68","Due to their importance for the radiation budget, liquid-containing clouds are a key component of the Arctic climate system. Depending on season, they can cool or warm the near-surface air. The radiative properties of these clouds depend strongly on cloud drop sizes, which are governed in part by the availability of cloud condensation nuclei. Here, we investigate how cloud drop sizes are modified in the presence of local emissions from industrial facilities at the North Slope of Alaska. For this, we use aircraft in situ observations of clouds and aerosols from the 5th Department of Energy Atmospheric Radiation Measurement (DOE ARM) Program's Airborne Carbon Measurements (ACMEV) campaign obtained in summer 2015. Comparison of observations from an area with petroleum extraction facilities (Oliktok Point) with data from a reference area relatively free of anthropogenic sources (Utqiagvik/Barrow) represents an opportunity to quantify the impact of local industrial emissions on cloud properties. In the presence of local industrial emissions, the mean effective radii of cloud droplets are reduced from 12.2 to 9.4 μm, which leads to suppressed drizzle production and precipitation. At the same time, concentrations of refractory black carbon and condensation nuclei are enhanced below the clouds. These results demonstrate that the effects of anthropogenic pollution on local climate need to be considered when planning Arctic industrial infrastructure in a warming environment. © Author(s) 2017."
"7007168548;8378887500;8791306500;8256598200;55480930900;6507256381;55698492900;35334472800;6602579980;8256598400;56151622000;56273253000;8280398300;6603547594;","Diurnal variations of BrONO2 observed by MIPAS-B at midlatitudes and in the Arctic",2017,"10.5194/acp-17-14631-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038242404&doi=10.5194%2facp-17-14631-2017&partnerID=40&md5=69c32d0a0b6d6fb5e905da072a24a9df","The first stratospheric measurements of the diurnal variation in the inorganic bromine (Bry) reservoir species BrONO2 around sunrise and sunset are reported. Arctic flights of the balloon-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) were carried out from Kiruna (68° N, Sweden) in January 2010 and March 2011 inside the stratospheric polar vortices where diurnal variations of BrONO2 around sunrise have been observed. High nighttime BrONO2 volume mixing ratios of up to 21 pptv (parts per trillion by volume) were detected in late winter 2011 in the absence of polar stratospheric clouds (PSCs). In contrast, the amount of measured BrONO2 was significantly lower in January 2010 due to low available NO2 amounts (for the build-up of BrONO2/, the heterogeneous destruction of BrONO2 on PSC particles, and the gas-phase interaction of BrO (the source to form BrONO2) with ClO. A further balloon flight took place at midlatitudes from Timmins (49° N, Canada) in September 2014. Mean BrONO2 mixing ratios of 22 pptv were observed after sunset in the altitude region between 21 and 29 km. Measurements are compared and discussed with the results of a multi-year simulation performed with the chemistry climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC). The calculated temporal variation in BrONO2 largely reproduces the balloon-borne observations. Using the nighttime simulated ratio between BrONO2 and Bry , the amount of Bry observed by MIPAS-B was estimated to be about 21-25 pptv in the lower stratosphere. 1 Introduction Chlorine and bromine species play a dominant role in the contribution to ongoing stratospheric ozone depletion since the amount of equivalent effective stratospheric chlorine (chlorine and bromine) is predicted to return to 1980 values by 2050 at midlatitudes (Newman et al., 2007; Stolarski et al., 2010). BrONO2 is the most abundant inorganic bromine (Bry ) compound in the stratosphere, besides BrO (see, e.g., Brasseur and Solomon, 2005; Sinnhuber et al., 2009; Sinnhuber and Meul, 2015). BrONO2 is formed via the reaction with BrO and NO2. © Author(s) 2017."
"23978267300;7402469637;14023953700;36102858600;41762693400;","Climatology and interannual variability of dynamic variables in multiple reanalyses evaluated by the SPARC Reanalysis Intercomparison Project (S-RIP)",2017,"10.5194/acp-17-14593-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037690485&doi=10.5194%2facp-17-14593-2017&partnerID=40&md5=8e3ff4f2ade2e4e2b1401a04a0310fd8","'Two of the most basic parameters generated from a reanalysis are temperature and winds. Temperatures in the reanalyses are derived from conventional (surface and balloon), aircraft, and satellite observations.Winds are observed by conventional systems, cloud tracked, and derived from height fields, which are in turn derived from the vertical temperature structure. In this paper we evaluate as part of the SPARC Reanalysis Intercomparison Project (S-RIP) the temperature and wind structure of all the recent and past reanalyses. This evaluation is mainly among the reanalyses themselves, but comparisons against independent observations, such as HIRDLS and COSMIC temperatures, are also presented. This evaluation uses monthly mean and 2.5° zonal mean data sets and spans the satellite era from 1979- 2014. There is very good agreement in temperature seasonally and latitudinally among the more recent reanalyses (CFSR, MERRA, ERA-Interim, JRA-55, and MERRA-2) between the surface and 10 hPa. At lower pressures there is increased variance among these reanalyses that changes with season and latitude. This variance also changes during the time span of these reanalyses with greater variance during the TOVS period (1979-1998) and less variance afterward in the ATOVS period (1999-2014). There is a distinct change in the temperature structure in the middle and upper stratosphere during this transition from TOVS to ATOVS systems. Zonal winds are in greater agreement than temperatures and this agreement extends to lower pressures than the temperatures. Older reanalyses (NCEP/NCAR, NCEP/DOE, ERA-40, JRA-25) have larger temperature and zonal wind disagreement from the more recent reanalyses. All reanalyses to date have issues analysing the quasi-biennial oscillation (QBO) winds. Comparisons with Singapore QBO winds show disagreement in the amplitude of the westerly and easterly anomalies. The disagreement with Singapore winds improves with the transition from TOVS to ATOVS observations. Temperature bias characteristics determined via comparisons with a reanalysis ensemble mean (MERRA, ERAInterim, JRA-55) are similarly observed when compared with Aura HIRDLS and Aura MLS observations. There is good agreement among the NOAA TLS, SSU1, and SSU2 Climate Data Records and layer mean temperatures from the more recent reanalyses. Caution is advised for using reanalysis temperatures for trend detection and anomalies from a long climatology period as the quality and character of reanalyses may have changed over time. © Author(s) 2017."
"57199155232;26531637100;15019752400;57191329689;55995010900;7005219614;16549600900;","WRF-Chem simulated surface ozone over south Asia during the pre-monsoon: Effects of emission inventories and chemical mechanisms",2017,"10.5194/acp-17-14393-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037660569&doi=10.5194%2facp-17-14393-2017&partnerID=40&md5=15ae83c415a646a4f1a93ed187026d47","We evaluate numerical simulations of surface ozone mixing ratios over the south Asian region during the pre-monsoon season, employing three different emission inventories in the Weather Research and Forecasting model with Chemistry (WRF-Chem) with the second-generation Regional Acid Deposition Model (RADM2) chemical mechanism: the Emissions Database for Global Atmospheric Research - Hemispheric Transport of Air Pollution (EDGAR-HTAP), the Intercontinental Chemical Transport Experiment phase B (INTEX-B) and the Southeast Asia Composition, Cloud, Climate Coupling Regional Study (SEAC4RS). Evaluation of diurnal variability in modelled ozone compared to observational data from 15 monitoring stations across south Asia shows the model ability to reproduce the clean, rural and polluted urban conditions over this region. In contrast to the diurnal average, the modelled ozone mixing ratios during noontime, i.e. hours of intense photochemistry (11:30-16:30gIST - Indian Standard Time - UTC +5:30), are found to differ among the three inventories. This suggests that evaluations of the modelled ozone limited to 24gh average are insufficient to assess uncertainties associated with ozone buildup. HTAP generally shows 10-30gppbv higher noontime ozone mixing ratios than SEAC4RS and INTEX-B, especially over the north-west Indo-Gangetic Plain (IGP), central India and southern India. The HTAP simulation repeated with the alternative Model for Ozone and Related Chemical Tracers (MOZART) chemical mechanism showed even more strongly enhanced surface ozone mixing ratios due to vertical mixing of enhanced ozone that has been produced aloft. Our study indicates the need to also evaluate the O3 precursors across a network of stations and the development of high-resolution regional inventories for the anthropogenic emissions over south Asia accounting for year-to-year changes to further reduce uncertainties in modelled ozone over this region. © Author(s) 2017."
"57193321502;6603925960;57207507108;57193321831;6701705691;7003865921;56493740900;","The link between outgoing longwave radiation and the altitude at which a spaceborne lidar beam is fully attenuated",2017,"10.5194/amt-10-4659-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037619961&doi=10.5194%2famt-10-4659-2017&partnerID=40&md5=49c11595dc830ea4a2e2e74b451031fb","According to climate model simulations, the changing altitude of middle and high clouds is the dominant contributor to the positive global mean longwave cloud feedback. Nevertheless, the mechanisms of this longwave cloud altitude feedback and its magnitude have not yet been verified by observations. Accurate, stable, and long-term observations of a metric-characterizing cloud vertical distribution that are related to the longwave cloud radiative effect are needed to achieve a better understanding of the mechanism of longwave cloud altitude feedback. This study shows that the direct measurement of the altitude of atmospheric lidar opacity is a good candidate for the necessary observational metric. The opacity altitude is the level at which a spaceborne lidar beam is fully attenuated when probing an opaque cloud. By combining this altitude with the direct lidar measurement of the cloud-top altitude, we derive the effective radiative temperature of opaque clouds which linearly drives (as we will show) the outgoing longwave radiation. We find that, for an opaque cloud, a cloud temperature change of 1 K modifies its cloud radiative effect by 2 W m-2. Similarly, the longwave cloud radiative effect of optically thin clouds can be derived from their top and base altitudes and an estimate of their emissivity. We show with radiative transfer simulations that these relationships hold true at single atmospheric column scale, on the scale of the Clouds and the Earth's Radiant Energy System (CERES) instantaneous footprint, and at monthly mean 2° × 2° scale. Opaque clouds cover 35 % of the ice-free ocean and contribute to 73 % of the global mean cloud radiative effect. Thin-cloud coverage is 36 % and contributes 27 % of the global mean cloud radiative effect. The link between outgoing longwave radiation and the altitude at which a spaceborne lidar beam is fully attenuated provides a simple formulation of the cloud radiative effect in the longwave domain and so helps us to understand the longwave cloud altitude feedback mechanism."
"35503801600;","Why would apparent κ linearly change with O/C? Assessing the role of volatility, solubility, and surface activity of organic aerosols",2017,"10.1080/02786826.2017.1352082","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85025674507&doi=10.1080%2f02786826.2017.1352082&partnerID=40&md5=cbecb9fefd1f136f36160257d97e64bd","Correlations between O/C and cloud condensation nucleus activity, represented by κ, are a computationally efficient approach to estimate the impact of aerosol aging on cloud formation and climate; however, previously reported correlations between these two variables are empirical and vary widely in their slopes and extrapolations to high O/C values. This study proposes a theoretical framework that bridges elemental ratios, volatility, solubility, and κ. The framework estimates intrinsic κ based on molecular formulas of organics composed of carbon, oxygen, and hydrogen that partition to condensed phase, and then it estimates apparent κ considering solubility distribution parameterized by O/C. This article applied the new framework to the two-dimensional volatility basis set (2D-VBS) and found that distribution of O/C and molecular size play key roles in determining apparent κ. For highly soluble organics, κ is dictated by gas-particle partitioning and it is unlikely for κ of organics to go beyond 0.3 in typical ambient organic material loadings. Sensitivity analysis showed that surface-active compounds are not likely to profoundly alter the overall trend within a reasonable range of surface activity. This framework provides a simple yet plausible explanation of why κ would and would not correlate with O/C; distributions of OA in the 2D-VBS as well as the presence of inorganic salts determine the trend. The framework opens up new opportunities to evaluate two-dimensional representations of organic aerosol aging using κ, a significant advancement from the current empirical linear fits to κ and O/C. Copyright © 2017 American Association for Aerosol Research. © 2017 American Association for Aerosol Research."
"57033686900;7202145115;15755995900;","Instantaneous linkages between clouds and large-scale meteorology over the Southern Ocean in observations and a climate model",2017,"10.1175/JCLI-D-17-0156.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034033364&doi=10.1175%2fJCLI-D-17-0156.1&partnerID=40&md5=473a6416ccfaae80bb86305ae8cbc6d8","Instantaneous, coincident, footprint-level satellite observations of cloud properties and radiation taken during austral summer over the Southern Ocean are used to study relationships between clouds and largescale meteorology. Cloud properties are very sensitive to the strength of vertical motion in the midtroposphere, and low-cloud properties are sensitive to estimated inversion strength, low-level temperature advection, and sea surface temperature. These relationships are quantified. An index for the meteorological anomalies associated with midlatitude cyclones is presented, and it is used to reveal the sensitivity of clouds to the meteorology within the warm and cold sectors of cyclones. The observed relationships between clouds and meteorology are compared to those in the Community Atmosphere Model, version 5 (CAM5), using satellite simulators. Low clouds simulated by CAM5 are too few, are too bright, and contain too much ice. In the cold sector of cyclones, the low clouds are also too sensitive to variations in the meteorology. When CAM5 is coupled with an updated boundary layer parameterization known as Cloud Layers Unified by Binormals (CLUBB), bias in the ice content of low clouds is dramatically reduced. More generally, this study demonstrates that examining the instantaneous time scale is a powerful approach to understanding the physical processes that control clouds and how they are represented in climate models. Such an evaluation goes beyond the cloud climatology and exposes model bias under various meteorological conditions. © 2017 American Meteorological Society."
"57210687618;16644246500;","Clouds, Circulation, and Climate Sensitivity in a Radiative-Convective Equilibrium Channel Model",2017,"10.1002/2017MS001111","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040726266&doi=10.1002%2f2017MS001111&partnerID=40&md5=3a49224d3d1b31f31cb6d8de66870849","Tropical cloud and circulation changes are large sources of uncertainty in future climate change. This problem owes partly to the scale separation between large-scale tropical dynamics (~104 km) and convective dynamics (~7 km), which generally requires parameterizing convection in models that resolve large-scale dynamics, or parameterizing (or omitting) large-scale dynamics in models that permit convection. Here we discuss simulations of radiative-convective equilibrium (RCE) across a wide range of surface temperatures in long-channel geometry—where the domain size and resolution marginally resolve both large-scale dynamics and convection. Self-aggregation of convection in these simulations spontaneously produces realistic dynamical regimes of large-scale vertical motion. The circulation weakens with surface warming but changes in the degree of self-aggregation depend on the metric that is used; there is no obvious trend in aggregation with warming. Surface warming causes an upward shift and decrease in area of high clouds, and a sharp decline in midlevel clouds, but no systematic trend in low cloud cover. We introduce a method for approximate radiative kernel feedback analysis in RCE, and apply it to both simulations in long-channel geometry and in a smaller square domain. The kernel-corrected cloud feedback is positive but its magnitude varies across temperatures. Compared to simulations that do not have aggregation, there is a more negative net feedback due to the effects of aggregation on relative humidity and cloud cover. These results are consistent with the hypothesis that self-aggregation moderately reduces climate sensitivity. © 2017. The Authors."
"54960984000;","Intensification of large-scale stretching of atmospheric pollutant clouds due to climate change",2017,"10.1175/JAS-D-17-0133.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040367733&doi=10.1175%2fJAS-D-17-0133.1&partnerID=40&md5=46b5d548e466c08f32fd176b2f036374","The aim of the paper is to investigate the question of how a changing climate influences the spreading of pollutants on continental and global scales. For characterizing the spreading, a measure of chaotic systems, called topological entropy, is used. This quantity describes the exponential stretching of pollutant clouds and, therefore, is related to the predictability and the complexity of the structure of a pollutant cloud. For the dispersion simulations the ERA-Interim database is used from 1979 to 2015. The simulations demonstrate that during this period the mean topological entropy slightly increases: the length of an initially line-like pollutant cloud advected for 10 (30) days in the atmosphere becomes 20%-65% (200%-400%) longer by the 2010s than in the 1980s. The mean topological entropy is found to be strongly correlated with the mean of the absolute value of the relative vorticity and only weakly linked to the mean temperature. © 2017 American Meteorological Society."
"55471474500;7401945370;7102731541;22934904700;57212988186;54983307800;9535769800;","Response of tropical cyclone activity and structure to global warming in a high-resolution global nonhydrostatic model",2017,"10.1175/JCLI-D-17-0068.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034055726&doi=10.1175%2fJCLI-D-17-0068.1&partnerID=40&md5=d03c357bfa2626c0afa4ac2b11023165","Future changes in tropical cyclone (TC) activity and structure are investigated using the outputs of a 14-km mesh climate simulation. A set of 30-yr simulations was performed under present-day and warmer climate conditions using a nonhydrostatic icosahedral atmospheric model with explicitly calculated convection. The model projected that the global frequency of TCs is reduced by 22.7%, the ratio of intense TCs is increased by 6.6%, and the precipitation rate within 100 km of the TC center increased by 11.8% under warmer climate conditions. These tendencies are consistent with previous studies using a hydrostatic global model with cumulus parameterization. The responses of vertical and horizontal structures to global warming are investigated for TCs with the same intensity categories. For TCs whose minimum sea level pressure (SLP) reaches less than 980 hPa, the model predicted that tangential wind increases in the outside region of the eyewall. Increases in the tangential wind are related to the elevation of the tropopause caused by global warming. The tropopause rise induces an upward extension of the eyewall, resulting in an increase in latent heating in the upper layers of the inclined eyewall. Thus, SLP is reduced underneath the warmed eyewall regions through hydrostatic adjustment. The altered distribution of SLP enhances tangential winds in the outward region of the eyewall cloud. Hence, this study shows that the horizontal scale of TCs defined by a radius of 12ms-1 surface wind is projected to increase compared with the same intensity categories for SLP less than 980 hPa. © 2017 American Meteorological Society."
"57189368502;55929969500;57194714440;57194720377;8662096300;56704049300;","Google Earth Engine: Planetary-scale geospatial analysis for everyone",2017,"10.1016/j.rse.2017.06.031","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021781951&doi=10.1016%2fj.rse.2017.06.031&partnerID=40&md5=c7f1b6e16c9e9c9b1753c79f159ac598","Google Earth Engine is a cloud-based platform for planetary-scale geospatial analysis that brings Google's massive computational capabilities to bear on a variety of high-impact societal issues including deforestation, drought, disaster, disease, food security, water management, climate monitoring and environmental protection. It is unique in the field as an integrated platform designed to empower not only traditional remote sensing scientists, but also a much wider audience that lacks the technical capacity needed to utilize traditional supercomputers or large-scale commodity cloud computing resources. © 2017 The Author(s)"
"57200302974;7403931916;8953038700;57195574170;8570871900;7404480911;6602513845;","Impact of Multiple Scattering on Longwave Radiative Transfer Involving Clouds",2017,"10.1002/2017MS001117","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040737991&doi=10.1002%2f2017MS001117&partnerID=40&md5=e46e5c25730996ccf6d930537da4d222","General circulation models (GCMs) are extensively used to estimate the influence of clouds on the global energy budget and other aspects of climate. Because radiative transfer computations involved in GCMs are costly, it is typical to consider only absorption but not scattering by clouds in longwave (LW) spectral bands. In this study, the flux and heating rate biases due to neglecting the scattering of LW radiation by clouds are quantified by using advanced cloud optical property models, and satellite data from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, Clouds and the Earth's Radiant Energy System (CERES), and Moderate Resolution Imaging Spectrometer (MODIS) merged products (CCCM). From the products, information about the atmosphere and clouds (microphysical and buck optical properties, and top and base heights) is used to simulate fluxes and heating rates. One-year global simulations for 2010 show that the LW scattering decreases top-of-atmosphere (TOA) upward flux and increases surface downward flux by 2.6 and 1.2 W/m2, respectively, or approximately 10% and 5% of the TOA and surface LW cloud radiative effect, respectively. Regional TOA upward flux biases are as much as 5% of global averaged outgoing longwave radiation (OLR). LW scattering causes approximately 0.018 K/d cooling at the tropopause and about 0.028 K/d heating at the surface. Furthermore, over 40% of the total OLR bias for ice clouds is observed in 350–500 cm−1. Overall, the radiative effects associated with neglecting LW scattering are comparable to the counterpart due to doubling atmospheric CO2 under clear-sky conditions. © 2017. The Authors."
"56517778400;36017183900;55706080300;7401945370;35329672300;55360542200;8067118800;56959736200;","Impact of lateral boundary errors on the simulation of clouds with a nonhydrostatic regional climate model",2017,"10.1175/MWR-D-17-0158.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040441733&doi=10.1175%2fMWR-D-17-0158.1&partnerID=40&md5=aa853a8d22d7e0d342db69affbf120e9","A nonhydrostatic, regional climate limited-area model (LAM) was used to analyze lateral boundary condition (LBC) errors and their influence on the uncertainties of regional models. Simulations using the fully compressible nonhydrostatic LAM (D-NICAM) were compared against the corresponding global quasi-uniform-grid Nonhydrostatic Icosahedral Atmospheric Model (NICAM) and a stretched-grid counterpart (S-NICAM). By this approach of sharing the same dynamical core and physical schemes, possible causes of model bias and LBC errors are isolated. The simulations were performed for a 395-day period from March 2011 through March 2012 with horizontal grid intervals of 14, 28, and 56 km in the region of interest. The resulting temporal mean statistics of the temperatures at 500 hPa were generally well correlated between the global and regional simulations, indicating that LBC errors had a minor impact on the large-scale flows. However, the time-varying statistics of the surface precipitation showed that the LBC errors lead to the unpredictability of convective precipitation, which affected the mean statistics of the precipitation distributions but induced only minor influences on the large-scale systems. Specifically, extratropical cyclones and orographic precipitation are not severely affected. It was concluded that the errors of the precipitation distribution are not due to the difference of the model configurations but rather to the uncertainty of the system itself. This study suggests that applications of ensemble runs, internal nudging, or simulations with longer time scales are needed to obtain more statistically significant results of the precipitation distribution in regional climate models. © 2017 American Meteorological Society."
"25924878400;7006387943;12645767500;55915206300;7003668116;7005035462;","The multisensor Advanced climatology of liquid water path (MAC-LWP)",2017,"10.1175/JCLI-D-16-0902.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85036645113&doi=10.1175%2fJCLI-D-16-0902.1&partnerID=40&md5=857580c9fc1a9c144be3b999c39e9fda","The Multisensor Advanced Climatology of Liquid Water Path (MAC-LWP), an updated and enhanced version of the University of Wisconsin (UWisc) cloud liquid water path (CLWP) climatology, currently provides 29 years (1988-2016) of monthly gridded (1°) oceanic CLWP information constructed using Remote Sensing Systems (RSS) intercalibrated 0.25°-resolution retrievals. Satellite sources include SSM/I, TMI, AMSR-E, WindSat, SSMIS, AMSR-2, and GMI. To mitigate spurious CLWP trends, the climatology is corrected for drifting satellite overpass times by simultaneously solving for the monthly average CLWP and the monthly mean diurnal cycle. In addition to a longer record and six additional satellite products, major enhancements relative to the UWisc climatology include updating the input to version 7 RSS retrievals, correcting for a CLWP bias (based on matchups to clear-sky MODIS scenes), and constructing a total (cloud + rain) liquid water path (TLWP) record for use in analyses of columnar liquid water in raining clouds. Because the microwave emission signal from cloud water is similar to that of precipitation-sized hydrometeors, greater uncertainty in the CLWP record is expected in regions of substantial precipitation. Therefore, the TLWP field can also be used as a quality-control screen, where uncertainty increases as the ratio of CLWP to TLWP decreases. For regions where confidence in CLWP is highest (i.e., CLWP:TLWP > 0.8), systematic differences in MAC CLWP relative to UWisc CLWP range from -15% (e.g., global oceanic stratocumulus decks) to +5%-10% (e.g., portions of the higher latitudes, storm tracks, and shallower convection regions straddling the ITCZ). The dataset is currently hosted at the Goddard Earth Sciences Data and Information Services Center. © 2017 American Meteorological Society."
"57196420477;8541590300;55675052700;7006091410;24281186100;55436296900;","An Iberian climatology of solar radiation obtained from WRF regional climate simulations for 1950–2010 period",2017,"10.1016/j.atmosres.2017.08.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032904974&doi=10.1016%2fj.atmosres.2017.08.016&partnerID=40&md5=e871fffe1c951513471092bfe85709dc","The mesoscale Weather Research and Forecasting (WRF) Model is used over the Iberian Peninsula to generate 60 years (1950–2010) of climate data, at 5 km resolution, in order to evaluate and characterize the incident shortwave downward radiation at the surface (SW ↓), in present climate. The simulated values of SW ↓ in the period 2000–2009 were compared with data measured in Spanish and Portuguese meteorological stations before and a statistical BIAS correction was applied using data from Clouds and the Earth's Radiant Energy System (CERES), on board four different satellites. The spatial and temporal comparison between WRF results and observations show a good agreement for the analyzed period, although the model overestimates observations. This overestimation has a mean normalized bias of about 7% after BIAS correction (or 17% for original WRF output). Additionally, the present simulation was confronted against another previously validated WRF simulation performed with different resolution and set of parametrizations, showing comparable results. WRF adequately reproduces the observational features of SW ↓ with correlation coefficients above 0.8 in annual and seasonal basis. 60 years of simulated SW ↓ over the Iberian Peninsula were produced, which showed annual mean values that range from 130 W/m2, in the northern regions, to a maximum of around 230 W/m2 in the southeast of the Iberian Peninsula (IP). SW ↓ over IP shows a positive gradient from north to south and from west to east, with local effects influenced by topography and distance to the coast. The analysis of the simulated cloud fraction indicates that clear sky days are found in > 30% of the period at the southern area of IP, particularly in the Algarve (Portugal) and Andalusia (Spain), and this value increases significantly in the summer season for values above 80%. © 2017 Elsevier B.V."
"13006677900;56506973700;7003510880;57195397685;","The Impact of Land-Surface Parameter Properties and Resolution on the Simulated Cloud-Topped Atmospheric Boundary Layer",2017,"10.1007/s10546-017-0286-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027730512&doi=10.1007%2fs10546-017-0286-6&partnerID=40&md5=3e5a2faffd213ad6634e486ce390aa66","Sensitivity tests using the ‘Consortium for Small Scale Modeling’ model in large-eddy simulation mode with a grid spacing of 100 m are performed to investigate the impact of the resolution of soil- and vegetation-related parameters on a cloud-topped boundary layer in a real-data environment. The reference simulation uses the highest land-surface parameter resolution available for operational purposes (300 m). The sensitivity experiments were conducted using spatial averaging of about 2.5km×2.5km and 10km×10km for the land-surface parameters and a completely homogeneous distribution for the whole model domain of about 70km×70km. Additionally, one experiment with a higher mean soil moisture and another with six mesoscale patches of enhanced or reduced soil moisture are performed. Boundary-layer clouds developed in all simulations. To assess the deviations of cloud cover on different scales within the model domain, we calculated the root-mean-square deviation (RMSD) between the sensitivity experiments and the reference simulation. The RMSD depends strongly on the spatial resolution at which cloud fields are compared. Different spatial resolutions of the cloud fields were generated by applying a low-pass filter. For all sensitivity experiments, large RMSD values occur for cut-off wavelengths < 1 km, reflecting the stochastic nature of convection, but they decrease rapidly for wavelengths between 1 and 5 km. For cut-off wavelengths >5km, the RMSD is still pronounced for the simulation with higher mean soil moisture. Additionally, for cut-off wavelengths between 5 and 30 km, considerable differences can be found for the experiment with mesoscale patches and for that with homogeneous land-surface parameters. Spatial averaging of land-surface parameters for areas of 2.5km×2.5km and 10km×10km results in larger patch sizes but simultaneously in reduced amplitudes of land-surface parameter anomalies and shows the lowest RMSD for all cut-off wavelengths. © 2017, Springer Science+Business Media B.V."
"6601958210;6603461810;","Possible Contribution of Variations in the Galactic Cosmic Ray Flux to the Global Temperature Rise in Recent Decades",2017,"10.1134/S0016793217070143","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042482796&doi=10.1134%2fS0016793217070143&partnerID=40&md5=e3a2af2b6c39769b9dd13f339f5fccc4","The field area of the Earth’s lower (<3.2 km) clouds is shown to correlate significantly with the intensity of galactic cosmic rays in 1983–2010, with the sign of correlation reversing in 2003. The same effect is discovered in the correlation between air temperatures in various regions of the Earth and the relativistic electron fluxes with energies of 30–300 KeV that precipitate in winter (December–February). An energy-balance climate model is used to estimate the possible contribution of lower clouds to the globally averaged temperature in the indicated period. It is shown that the consideration of lower clouds as a radiative forcing allows one to explain the global warming of the last 30 years without employing the hypothesis of anthropogenic greenhouse heating. © 2017, Pleiades Publishing, Ltd."
"25823648900;6507559416;36025052000;23092354000;6602356372;57194507875;57193567625;23976053900;55972529900;8615950900;7801488987;23105874800;23988800700;","Sensitivity of temperature to physical parameterization schemes of RegCM4 over the CORDEX-Southeast Asia region",2017,"10.1002/joc.5151","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020398553&doi=10.1002%2fjoc.5151&partnerID=40&md5=eb54166a80d4d5cec3bb7740f4fbed0d","This study examines the simulated temperature over Southeast Asia (SEA) using the Regional Climate Model version 4.3 (RegCM4.3), and its sensitivity to selected cumulus and ocean surface flux schemes. Model simulations were conducted for the SEA domain at 36 km spatial resolution for the period of 1989–2008, as part of the Southeast Asia Regional Climate Downscaling/Coordinated Regional Climate Downscaling Experiment-Southeast Asia (SEACLID/CORDEX-Southeast Asia) project. A total of 18 sensitivity experiments were conducted with a combination of six cumulus parameterization schemes and three ocean surface flux schemes. The model's skill in representing mean, maximum and minimum temperatures is evaluated against observed gridded data sets. Results indicate a predominant cold bias in all simulations, particularly over mainland SEA (Indochina) during the season of December to February. Nevertheless, the seasonal correlation is highest over this region. The cold bias of the model is also evident in the temperature distributions, such that there are more cold months than observed, which may be associated with the underestimation of the daily maximum temperature. A few simulations also reveal a warm bias over some areas in the Maritime Continent. Further examination shows that both radiative and surface fluxes influence the simulated temperature, which may also have effects that partially offset each other in some areas. Comparison of the sensitivity experiments reveals differences in model performance, and underlines the importance in choosing the appropriate configuration for RegCM4.3 before it is used to downscale climate projections, particularly for the SEA region. This study also shows a strong influence of the choice of cumulus scheme on temperature. Based on performance metrics for temperature among the schemes tested, the Massachusetts Institute of Technology (MIT) Emanuel cumulus scheme and the Biosphere-Atmosphere Transfer Scheme version 1e (BATS1e) ocean surface flux scheme can be used in future simulations for the region. © 2017 Royal Meteorological Society"
"56898397000;55544443300;55686667100;","Dependence of Arctic climate on the latitudinal position of stationary waves and to high-latitudes surface warming",2017,"10.1007/s00382-017-3543-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011826959&doi=10.1007%2fs00382-017-3543-y&partnerID=40&md5=77e5481276a77ec11510c4cbd464ab1e","Previous studies suggest large uncertainties in the stationary wave response under global warming. Here, we investigate how the Arctic climate responds to changes in the latitudinal position of stationary waves, and to high-latitudes surface warming that mimics the effect of Arctic sea ice loss under global warming. To generate stationary waves in an atmospheric model coupled to slab ocean, a series of experiments is performed where the thermal forcing with a zonal wavenumber-2 (with zero zonal-mean) is prescribed at the surface at different latitude bands in the Northern Hemisphere. When the stationary waves are generated in the subtropics, the cooling response dominates over the warming response in the lower troposphere due to cloud radiative effects. Then, the low-level baroclinicity is reduced in the subtropics, which gives rise to a poleward shift of the eddy driven jet, thereby inducing substantial cooling in the northern high latitudes. As the stationary waves are progressively generated at higher latitudes, the zonal-mean climate state gradually becomes more similar to the integration with no stationary waves. These differences in the mean climate affect the Arctic climate response to high-latitudes surface warming. Additional surface heating over the Arctic is imposed to the reference climates in which the stationary waves are located at different latitude bands. When the stationary waves are positioned at lower latitudes, the eddy driven jet is located at higher latitude, closer to the prescribed Arctic heating. As baroclinicity is more effectively perturbed, the jet shifts more equatorward that accompanies a larger reduction in the poleward eddy transport of heat and momentum. A stronger eddy-induced descending motion creates greater warming over the Arctic. Our study calls for a more accurate simulation of the present-day stationary wave pattern to enhance the predictability of the Arctic warming response in a changing climate. © 2017, Springer-Verlag Berlin Heidelberg."
"35768456900;7004978125;55575781400;","Seasonal synchronization of a simple stochastic dynamical model capturing El Niño diversity",2017,"10.1175/JCLI-D-17-0174.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85036609014&doi=10.1175%2fJCLI-D-17-0174.1&partnerID=40&md5=020955747ba04f0105f6f9c447e0865e","Recently, a simple stochastic dynamical model was developed that automatically captures the diversity and intermittency of El Niño-Southern Oscillation (ENSO) in nature, where state-dependent stochastic wind bursts and nonlinear advection of sea surface temperature (SST) are coupled to simple ocean-atmosphere processes that are otherwise deterministic, linear, and stable. In the present article, it is further shown that the model can reproduce qualitatively the ENSO synchronization (or phase locking) to the seasonal cycle in nature. This goal is achieved by incorporating a cloud radiative feedback that is derived naturally from the model's atmosphere dynamics with no ad hoc assumptions and accounts in simple fashion for the marked seasonal variations of convective activity and cloud cover in the eastern Pacific. In particular, the weak convective response to SSTs in boreal fall favors the eastern Pacific warming that triggers El Niño events while the increased convective activity and cloud cover during the following spring contributes to the shutdown of those events by blocking incoming shortwave solar radiations. In addition to simulating the ENSO diversity with realistic non-Gaussian statistics in different Niño regions, the eastern Pacific moderate and super El Niño and the central Pacific El Niño and La Niña show a realistic chronology with a tendency to peak in boreal winter as well as decreased predictability in spring consistent with the persistence barrier in nature. The incorporation of other possible seasonal feedbacks in the model is also documented for completeness. © 2017 American Meteorological Society."
"57202140804;6701346974;","Changes in temperature and precipitation extremes in superparameterized CAM in response to warmer SSTs",2017,"10.1175/JCLI-D-17-0214.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85036644456&doi=10.1175%2fJCLI-D-17-0214.1&partnerID=40&md5=e31b7991e7187c155f89974a97eca6c3","Subdaily temperature and precipitation extremes in response to warmer SSTs are investigated on a global scale using the superparameterized (SP) Community Atmosphere Model (CAM), in which a cloud-resolving model is embedded in each CAM grid column to simulate convection explicitly. Two 10-yr simulations have been performed using present climatological sea surface temperature (SST) and perturbed SST climatology derived from the representative concentration pathway 8.5 (RCP8.5) scenario. Compared with the conventional CAM, SP-CAM simulates colder temperatures and more realistic intensity distribution of precipitation, especially for heavy precipitation. The temperature and precipitation extremes have been defined by the 99th percentile of the 3-hourly data. For temperature, the changes in the warm and cold extremes are generally consistent between CAM and SP-CAM, with larger changes in warm extremes at low latitudes and larger changes in cold extremes at mid-to-high latitudes. For precipitation, CAM predicts a uniform increase of frequency of precipitation extremes regardless of the rain rate, while SP-CAM predicts a monotonic increase of frequency with increasing rain rate and larger change of intensity for heavier precipitation. The changes in 3-hourly and daily temperature extremes are found to be similar; however, the 3-hourly precipitation extremes have a significantly larger change than daily extremes. The Clausius-Clapeyron scaling is found to be a relatively good predictor of zonally averaged changes in precipitation extremes over midlatitudes but not as good over the tropics and subtropics. The changes in precipitable water and large-scale vertical velocity are equally important to explain the changes in precipitation extremes. © 2017 American Meteorological Society."
"56194959500;57193521890;6603288856;23994716100;","Land Surface Phenology in the Tropics: The Role of Climate and Topography in a Snow-Free Mountain",2017,"10.1007/s10021-017-0123-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014520479&doi=10.1007%2fs10021-017-0123-2&partnerID=40&md5=59900ddb386d16f5071abd9949baf90d","Leaf phenology represents a major temporal component of ecosystem functioning, and understanding the drivers of seasonal variation in phenology is essential to understand plant responses to climate change. We assessed the patterns and drivers of land surface phenology, a proxy for leafing phenology, for the meridional Espinhaço Range, a South American tropical mountain comprising a mosaic of savannas, dry woodlands, montane vegetation and moist forests. We used a 14-year time series of MODIS/NDVI satellite images, acquired between 2001 and 2015, and extracted phenological indicators using the TIMESAT algorithm. We obtained precipitation data from the Tropical Rainfall Measuring Mission, land surface temperature from the MODIS MOD11A2 product, and cloud cover frequency from the MODIS MOD09GA product. We also calculated the topographic wetness index and simulated clear-sky radiation budgets based on the SRTM elevation model. The relationship between phenology and environmental drivers was assessed using general linear models. Temporal displacement in the start date of the annual growth season was more evident than variations in season length among vegetation types, indicating a possible temporal separation in the use of resources. Season length was inversely proportional to elevation, decreasing 1.58 days per 100 m. Green-up and senescence rates were faster where annual temperature amplitude was higher. We found that water and light availability, modulated by topography, are the most likely drivers of land surface phenology in the region, determining the start, end and length of the growing season. Temperature had an important role in determining the rates of leaf development and the strength of vegetation seasonality, suggesting that tropical vegetation is also sensitive to latitudinal temperature changes, regardless of the elevational gradient. Our work improves the current understanding of phenological strategies in the seasonal tropics and emphasizes the importance of topography in shaping light and water availability for leaf development in snow-free mountains. © 2017, Springer Science+Business Media New York."
"57140720000;23037141700;6506626745;","Seawater desalination using inclined stepped solar still with copper trays in a wet tropical climate",2017,"10.1016/j.desal.2017.09.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032272398&doi=10.1016%2fj.desal.2017.09.020&partnerID=40&md5=61db6d17baf22690ac4182acc5a1abca","In this study, a copper inclined stepped solar still was designed and fabricated to study the seawater desalination productivity of copper inclined stepped solar stills. The experimental setup mainly consists of two parts: a seawater settling and feeding tank and an inclined stepped solar still. The inclined stepped solar still with internal dimensions of L 1.8 m, W 1.2 m, and H 0.20 m consisted of 28 trays, and the tray dimensions are 0.6 m in height and 1.2 m in length. Its performance was tested in Bangi City - Malaysia, under Malaysian environmental conditions in the period from September 2016 to December 2016. The inclined stepped solar still was sealed to reduce vapour leakage to the environment. The experiment studies the effect of different environmental parameters (solar intensity, ambient temperature, wind velocity, humidity and cloud coverage) and operational parameters on the system productivity (water production and glass out, inner, vapour, water and tray “basin” temperature). The result shows that the productivity of the solar still was highly affected by environmental parameters. For example, the increase in solar radiation and ambient temperature increases the still temperature, and the difference between the cover inner and outer temperatures enhances the condensing process and water productivity. However, the decrease in humidity increases the productivity, the wind velocity significantly reduces the (Ti − To) difference temperature, which adversely affects the productivity of the system, and the cloud coverage affects the solar radiation intensity. The productivity was 4383 mL/m2d; the best hourly efficiency was approximately 58% at 17:00, which can be explained by the highest solar radiation and ambient temperature with respect to time lag for the system. © 2017 Elsevier B.V."
"57199840525;57204307377;56304460900;57199841059;7404978416;55277716700;","On the growth and detectability of land plants on habitable planets around M Dwarfs",2017,"10.1089/ast.2016.1617","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038428387&doi=10.1089%2fast.2016.1617&partnerID=40&md5=c59171cfe554bd58089d7d16bd72a65d","One signature of life on Earth is the vegetation red edge (VRE) feature of land plants, a dramatic change of reflectivity at wavelength near 0.7 μm. Potentially habitable planets around M dwarfs are tidally locked, which can limit the distribution of land plants. In this study, we used a biogeochemical model to investigate the distribution of land plants on potentially habitable planets around M dwarfs driven by climate data produced in a general circulation model (GCM). When considering the effects of clouds, the observation time needed for VRE detection on nearby p = 1 exoplanets around nearby M dwarfs is on the order of days using a 25 m2 telescope if a large continent faces Earth during observations. For p = 1.5 exoplanets, the detection time could be similar if land plants developed the capability to endure a dark/cold environment for extended periods of time and the continent configuration favors observations. Our analysis suggests that hypothetical exovegetation VRE features are easier to detect than Earth vegetation and that VRE detection is possible for nearby exoplanets even under cloudy conditions. © Mary Ann Liebert, Inc. 2017."
"55823467500;57204886915;7006127310;7203062717;7006198994;7003278104;7003545639;","MJO simulation in CMIP5 climate models: MJO skill metrics and process-oriented diagnosis",2017,"10.1007/s00382-017-3558-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015916306&doi=10.1007%2fs00382-017-3558-4&partnerID=40&md5=a089d759c58b8c6e415a1893ab168a5d","The Madden-Julian Oscillation (MJO) simulation diagnostics developed by MJO Working Group and the process-oriented MJO simulation diagnostics developed by MJO Task Force are applied to 37 Coupled Model Intercomparison Project phase 5 (CMIP5) models in order to assess model skill in representing amplitude, period, and coherent eastward propagation of the MJO, and to establish a link between MJO simulation skill and parameterized physical processes. Process-oriented diagnostics include the Relative Humidity Composite based on Precipitation (RHCP), Normalized Gross Moist Stability (NGMS), and the Greenhouse Enhancement Factor (GEF). Numerous scalar metrics are developed to quantify the results. Most CMIP5 models underestimate MJO amplitude, especially when outgoing longwave radiation (OLR) is used in the evaluation, and exhibit too fast phase speed while lacking coherence between eastward propagation of precipitation/convection and the wind field. The RHCP-metric, indicative of the sensitivity of simulated convection to low-level environmental moisture, and the NGMS-metric, indicative of the efficiency of a convective atmosphere for exporting moist static energy out of the column, show robust correlations with a large number of MJO skill metrics. The GEF-metric, indicative of the strength of the column-integrated longwave radiative heating due to cloud-radiation interaction, is also correlated with the MJO skill metrics, but shows relatively lower correlations compared to the RHCP- and NGMS-metrics. Our results suggest that modifications to processes associated with moisture-convection coupling and the gross moist stability might be the most fruitful for improving simulations of the MJO. Though the GEF-metric exhibits lower correlations with the MJO skill metrics, the longwave radiation feedback is highly relevant for simulating the weak precipitation anomaly regime that may be important for the establishment of shallow convection and the transition to deep convection. © 2017, The Author(s)."
"55436296900;6603160042;25228107900;57209472707;57087246900;57206755394;","On the movement of tropical cyclone LEHAR",2017,"10.1007/s41748-017-0025-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062273911&doi=10.1007%2fs41748-017-0025-7&partnerID=40&md5=bf7094bdacd0572735e8a273a9585b35","Purpose: In this paper, an attempt has been made to delineate the physical processes which lead to the westward movement of the North Indian Ocean tropical cyclone LEHAR. Methods: The Advanced Weather Research and Forecasting (ARW) model is used to simulate LEHAR with 27 and 9 km resolutions. In addition to that, all terms of the complete vorticity equation are computed to obtain the contribution of each term for the vorticity tendency. The vorticity tendency is calculated in four sectors, namely northwest, northeast, southwest, and southeast and assumed that the cyclone moves from its existing location to the nearest point where the vortices tendency is maximum. Results: The results indicate that the model performed well in simulating the characteristics of cyclone compared with the Satellite and other observations. It is noticed that the vorticity stretching term contributes most to the positive vorticity tendency. The second highest contribution is from the horizontal advection thus indicating the secondary importance of steering. Conclusions: The distribution of lightning flash rates are higher in the SW and followed by NW sectors of the cyclone indicate more strong convective clouds are in SW sector. The equivalent potential temperatures (θe) at different stages of before, during and after the mature stage of the cyclone reveals that the wind-induced surface heat (WISH) exchange process is a plausible mechanism for the intensification of LEHAR. © 2017, Springer International Publishing AG, part of Springer Nature."
"57203297300;56265041500;7005498995;","Bayesian Merging of MISR and MODIS Aerosol Optical Depth Products Using Error Distributions from AERONET",2017,"10.1109/JSTARS.2017.2734331","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028508253&doi=10.1109%2fJSTARS.2017.2734331&partnerID=40&md5=29fb1c8d22f0db679d7520109db1300d","Aerosol Optical depth (AOD) routinely retrieved by spaceborne sensors (e.g., MODIS and MISR) is widely used in studies focused on atmospheric aerosol characterization, their variability/trends, and environmental/climate impacts. Despite significant advancement in the understanding of aerosol loading patterns, there exist global/regional differences among AOD products from various satellite sensors; owing to differences in retrieval algorithms, spatial/temporal resolution and sampling, and cloud-screening schemes. A merged AOD dataset combining multiple satellite retrievals is therefore desirable, which utilizes the strengths of individual products, and at the same time reduces biases relative to ground-based measurements (e.g., from aerosol robotic network (AERONET)). In view of this, a Level-2 ''merged'' AOD dataset based on MODIS and MISR retrievals is developed in this study using Bayesian principles, which takes into account the error distribution of AOD from AERONET data. The merged AOD dataset is demonstrated over the Indo-Gangetic Plains, in southern Asia, and is intercompared with existing satellite and AERONET data. The RMSE of the merged AOD data (0.08-0.13) is lower than the MISR and MODIS retrievals. Additionally, the merged AOD data have higher correlation with AERONET data (r within 0.89-0.93), compared to MISR (0.82-0.89) and MODIS (0.76-0.77) data. In terms of the expected error (EE), the accuracy of merged data is found to be higher, with larger percent of merged AOD within the EE envelope (74.7%-88.7%) compared to MISR (62.7%-84.9%) and MODIS (67.9%-69.8%) data. The merging methodology and resulting dataset are especially relevant in the scenario of fusing multisensor retrievals for producing long-term satellite-based climate data records. © 2008-2012 IEEE."
"6602996168;56942509000;56604019400;","Simulations of the effect of intensive biomass burning in July 2015 on Arctic radiative budget",2017,"10.1016/j.atmosenv.2017.10.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032014195&doi=10.1016%2fj.atmosenv.2017.10.015&partnerID=40&md5=b9dfdb985ab7944a45b4900adf9dbb55","The impact of biomass burning (BB) on aerosol optical properties and radiative budget in the polar region following an intense boreal fire event in North America in July 2015 is explored in this paper. Presented data are obtained from the Navy Aerosol Analysis and Prediction System (NAAPS) reanalysis and the Fu-Liou radiative transfer model. NAAPS provides particle concentrations and aerosol optical depth (AOD) at 1° x 1° spatial and 6-hourly temporal resolution, its AOD and vertical profiles were validated with field measurements for this event. Direct aerosol radiative forcings (ARF) at the surface, the top of the atmosphere (TOA) and within the atmosphere are calculated for clear-sky and all-sky conditions, with the surface albedo and cloud properties constrained by satellite retrievals. The mean ARFs at the surface, the TOA, and within the atmosphere averaged for the north pole region (latitudes north of 75.5N) and the study period (July 5–15, 2015) are −13.1 ± 2.7, 0.3 ± 2.1, and 13.4 ± 2.7 W/m2 for clear-sky and −7.3 ± 1.8, 5.0 ± 2.6, and 12.3 ± 1.6 W/m2 for all-sky conditions respectively. Local ARFs can be a several times larger e.g. the clear-sky surface and TOA ARF reach over Alaska −85 and −30 W/m2 and over Svalbard −41 and −20 W/m2 respectively. The ARF is found negative at the surface (almost zero over high albedo region though) with the maximum forcing over the BB source region, and weaker forcing under all-sky conditions compared to the clear-sky conditions. Unlike the ARFs at the surface and within the atmosphere, which have consistent forcing signs all over the polar region, the ARF at the TOA changes signs from negative (cooling) over the source region (Alaska) to positive (heating) over bright surfaces (e.g., Greenland) because of strong surface albedo effect. NAAPS simulations also show that the transported BB particle over the Arctic are in the low-to-middle troposphere and above low-level clouds, resulting in little difference in ARFs at the TOA between clear- and all-sky conditions over the regions with high surface albedo. Over dark surfaces, the negative TOA forcing increases with AOD about 50% slower under all-sky conditions compared to clear-sky case. The boreal BB event resulted in large magnitude of ARFs and the high variabilities of the forcings over the polar region has a significant impact on the polar weather conditions and important implications for the polar climate. © 2017 Elsevier Ltd"
"50660894900;57204886915;7102567936;57193132723;56093699900;","Characterization of Moist Processes Associated With Changes in the Propagation of the MJO With Increasing CO2",2017,"10.1002/2017MS001040","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038221959&doi=10.1002%2f2017MS001040&partnerID=40&md5=d1ffb4892037ed4c9b34dd59b3ea9b9e","The processes that lead to changes in the propagation and maintenance of the Madden-Julian Oscillation (MJO) as a response to increasing CO2 are examined by analyzing moist static energy budget of the MJO in a series of NASA GISS model simulations. It is found changes in MJO propagation is dominated by several key processes. Horizontal moisture advection, a key process for MJO propagation, is found to enhance predominantly due to an increase in the mean horizontal moisture gradients. The terms that determine the strength of the advecting wind anomalies, the MJO horizontal scale and the dry static stability, are found to exhibit opposing trends that largely cancel out. Furthermore, reduced sensitivity of precipitation to changes in column moisture, i.e., a lengthening in the convective moisture adjustment time scale, also opposes enhanced propagation. The dispersion relationship of Adames and Kim, which accounts for all these processes, predicts an acceleration of the MJO at a rate of ∼3.5% K−1, which is consistent with the actual phase speed changes in the simulation. For the processes that contribute to MJO maintenance, it is found that damping by vertical MSE advection is reduced due to the increasing vertical moisture gradient. This weaker damping is nearly canceled by weaker maintenance by cloud-radiative feedbacks, yielding the growth rate from the linear moisture mode theory nearly unchanged with the warming. Furthermore, the estimated growth rates are found to be a small, negative values, suggesting that the MJO in the simulation is a weakly damped mode. © 2017. The Authors."
"39361982900;35460698500;57200101288;7006421134;55723405300;16162149600;7003567733;8750834400;55476297000;56478591100;13906856500;14020534200;57202695106;36155758500;6701778684;7202459859;57204901815;57199426611;9274820400;9249296100;57195023147;6506322240;23097415100;23486850100;35168359400;44661319600;8420354200;55576176900;11241356400;36155343600;36039858000;","Overview of Akatsuki data products: definition of data levels, method and accuracy of geometric correction",2017,"10.1186/s40623-017-0749-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037721330&doi=10.1186%2fs40623-017-0749-5&partnerID=40&md5=939edbea2dcd2e8ece1285373ddd2676","We provide an overview of data products from observations by the Japanese Venus Climate Orbiter, Akatsuki, and describe the definition and content of each data-processing level. Levels 1 and 2 consist of non-calibrated and calibrated radiance (or brightness temperature), respectively, as well as geometry information (e.g., illumination angles). Level 3 data are global-grid data in the regular longitude–latitude coordinate system, produced from the contents of Level 2. Non-negligible errors in navigational data and instrumental alignment can result in serious errors in the geometry calculations. Such errors cause mismapping of the data and lead to inconsistencies between radiances and illumination angles, along with errors in cloud-motion vectors. Thus, we carefully correct the boresight pointing of each camera by fitting an ellipse to the observed Venusian limb to provide improved longitude–latitude maps for Level 3 products, if possible. The accuracy of the pointing correction is also estimated statistically by simulating observed limb distributions. The results show that our algorithm successfully corrects instrumental pointing and will enable a variety of studies on the Venusian atmosphere using Akatsuki data. © 2017, The Author(s)."
"23009358600;22234792700;56098531800;8369807100;7402674597;","Unmanned aircraft system advances health mapping of fragile polar vegetation",2017,"10.1111/2041-210X.12833","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85023629657&doi=10.1111%2f2041-210X.12833&partnerID=40&md5=c6a881ed2376891c15c947b5153eb8b8","Plants like mosses can be sensitive stress markers of subtle shifts in Arctic and Antarctic environmental conditions, including climate change. Traditional ground-based monitoring of fragile polar vegetation is, however, invasive, labour intensive and physically demanding. High-resolution multispectral satellite observations are an alternative, but even their recent highest achievable spatial resolution is still inadequate, resulting in a significant underestimation of plant health due to spectral mixing and associated reflectance impurities. To resolve these obstacles, we have developed a new method that uses low-altitude unmanned aircraft system (UAS) hyperspectral images of sub-decimeter spatial resolution. Machine-learning support vector regressions (SVR) were employed to infer Antarctic moss vigour from quantitative remote sensing maps of plant canopy chlorophyll content and leaf density. The same maps were derived for comparison purposes from the WorldView-2 high spatial resolution (2.2 m) multispectral satellite data. We found SVR algorithms to be highly efficient in estimating plant health indicators with acceptable root mean square errors (RMSE). The systematic RMSEs for chlorophyll content and leaf density were 3.5–6.0 and 1.3–2.0 times smaller, respectively, than the unsystematic errors. However, application of correctly trained SVR machines on space-borne multispectral images considerably underestimated moss chlorophyll content, while stress indicators retrieved from UAS data were found to be comparable with independent field measurements, providing statistically significant regression coefficients of determination (median r2 =.50, pt test =.0072). This study demonstrates the superior performance of a cost-efficient UAS mapping platform, which can be deployed even under the continuous cloud cover that often obscures optical high-altitude airborne and satellite observations. Antarctic moss vigour maps of appropriate resolution could provide timely and spatially explicit warnings of environmental stress events, including those triggered by climate change. Since our polar vegetation health assessment method is based on physical principles of quantitative spectroscopy, it could be adapted to other short-stature and fragmented plant communities (e.g. tundra grasslands), including alpine and desert regions. It therefore shows potential to become an operational component of any ecological monitoring sensor network. © 2017 The Authors. Methods in Ecology and Evolution © 2017 British Ecological Society"
"56315238900;55941133900;57194552342;57194541151;36836439900;","Bacterial community composition in rainwater associated with synoptic weather in an area downwind of the Asian continent",2017,"10.1016/j.scitotenv.2017.06.052","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020709005&doi=10.1016%2fj.scitotenv.2017.06.052&partnerID=40&md5=b54cd4466dbae12de2ffd74cc83eeeb4","Bacteria are abundant in atmospheric waters and can be disseminated by precipitation to the surface of the Earth, potentially influencing ecosystems, public health and climate. However, data on bacterial communities in rainwater, especially on the association with weather, are very limited. In this study, rainwater was collected at the coastal city Kumamoto, southwestern Japan, in 2015. The bacterial communities in fourteen samples were identified using 16S rRNA sequencing and compared according to the rain types at the synoptic scale, i.e., cyclones, Meiyu and non-Meiyu stationary fronts, and typhoons. Diverse bacterial communities were present in all four types of rainwater and were dominated by the phyla Proteobacteria (37%), Bacteroidetes (16%), Cyanobacteria (14%), Actinobacteria (9%), Acidobacteria (8%) and Firmicutes (5%). Approximately half of the phyla (16 out of 33) were common among the rain types. The operational taxonomic units (OTUs) common among the four types of rainwater represented the majority (averagely 74%) of the sequences, indicating the predominance of common bacterial OTUs regardless of rain type. On the other hand, the synoptic weather systems and the origins of air masses associated with the rain likely resulted in distinct bacterial communities. High fractions of bacterial soil indicator taxa signified the large contribution of bacteria from soils. Genera containing ice nucleation-active bacteria were identified in all samples except one typhoon rain sample. Marine bacterial taxa, e.g., Pseudoalteromonas, Synechococcus and Marinobacter, were detected in several samples, indicating the dispersal of marine bacteria via clouds and rainwater. Fecal indicator bacteria were also detected in all samples. Thus, the bacteria in the four types of rainwater were characterized by largely overlapping communities with some differences in community composition, indicating that rain is an efficient pathway for the dissemination of bacterial communities in nature and links continental, marine and island ecosystems. © 2017 Elsevier B.V."
"57189241577;23471239000;7006114701;","Annual seasonality extraction using the cubic spline function and decadal trend in temporal daytime MODIS LST data",2017,"10.3390/rs9121254","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038207908&doi=10.3390%2frs9121254&partnerID=40&md5=7ddc40a72fc988a09474653ed394f86c","Examining climate-related satellite data that strongly relate to seasonal phenomena requires appropriate methods for detecting the seasonality to accommodate different temporal resolutions, high signal variability and consecutive missing values in the data series. Detection of satellite-based Land Surface Temperature (LST) seasonality is essential and challenging due to missing data and noise in time series data, particularly in tropical regions with heavy cloud cover and rainy seasons. We used a semi-parametric approach, involving the cubic spline function with the annual periodic boundary condition and weighted least square (WLS) regression, to extract annual LST seasonal pattern without attempting to estimate the missing values. The time series from daytime Aqua eight-day MODIS LST located on Phuket Island, southern Thailand, was selected for seasonal extraction modelling across three different land cover types. The spline-based technique with appropriate number and placement of knots produces an acceptable seasonal pattern of surface temperature time series that reflects the actual local season and weather. Finally, the approach was applied to the morning and afternoon MODIS LST datasets (MOD11A2 and MYD11A2) to demonstrate its application on seasonally-adjusted long-term LST time series. The surface temperature trend in both space and time was examined to reveal the overall 10-year period trend of LST in the study area. The result of decadal trend analysis shows that various Land Use and Land Cover (LULC) types have increasing, but variable surface temperature trends. © 2017 by the author."
"36169127300;7102139429;6507695544;15765165800;56975936000;","Periodic signals of climatic variables and water quality in a river – eutrophic pond – wetland cascade ecosystem tracked by wavelet coherence analysis",2017,"10.1016/j.ecolind.2017.07.018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026214808&doi=10.1016%2fj.ecolind.2017.07.018&partnerID=40&md5=cb6f3e2351e4df1d0e01439140564be6","Lakes are sensitive to changes in their environmental boundary conditions that can be indicated in the periodic behavior of water quality variables. The present work aims to assess the degree to which common annual periodic behavior is present (1994–2010) in the meteorological parameters (global radiation, air temperature, cloud cover), streamflow; and five primary nutrients (e.g. total phosphorus, nitrate-nitrogen) as possible indicators of ecosystem vulnerability in four different ecosystems using wavelet coherence analysis. The cascade system is located in the mouth of a shallow river where the water flows through a eutrophic pond then a disturbed/undisturbed macrophyte covered wetland reaching a large shallow lake. The results highlight the differing abilities of the elements of the cascade of ecosystems to follow seasonality. The changes in water quality (nutrient cycle) in the eutrophic pond most closely mirror meteorological seasonality. The vulnerability of the wetland ecosystem was expressed by its decreased capacity to follow seasonal changes due to high algae loads and additional inflows. Moreover, the wetland proved to be weak and unstable regarding phosphorus and nitrogen retention. With the successful application of wavelet coherence analysis to the “black-box” cascade system the study sets an example for the implications of the method in such combined or stand-alone natural/partially-constructed ecosystems. © 2017 Elsevier Ltd"
"55464707800;7003557623;36739093800;57190177072;35570142700;6603661662;6603839405;","Impact of data model and point density on aboveground forest biomass estimation from airborne LiDAR",2017,"10.1186/s13021-017-0073-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013354732&doi=10.1186%2fs13021-017-0073-1&partnerID=40&md5=de374c6488f4a2c5b2b7655ae678f834","Background: Accurate estimation of aboveground forest biomass (AGB) and its dynamics is of paramount importance in understanding the role of forest in the carbon cycle and the effective implementation of climate change mitigation policies. LiDAR is currently the most accurate technology for AGB estimation. LiDAR metrics can be derived from the 3D point cloud (echo-based) or from the canopy height model (CHM). Different sensors and survey configurations can affect the metrics derived from the LiDAR data. We evaluate the ability of the metrics derived from the echo-based and CHM data models to estimate AGB in three different biomes, as well as the impact of point density on the metrics derived from them. Results: Our results show that differences among metrics derived at different point densities were significantly different from zero, with a larger impact on CHM-based than echo-based metrics, particularly when the point density was reduced to 1 point m-2. Both data models-echo-based and CHM-performed similarly well in estimating AGB at the three study sites. For the temperate forest in the Sierra Nevada Mountains, California, USA, R2 ranged from 0.79 to 0.8 and RMSE (relRMSE) from 69.69 (35.59%) to 70.71 (36.12%) Mg ha-1 for the echo-based model and from 0.76 to 0.78 and 73.84 (37.72%) to 128.20 (65.49%) Mg ha-1 for the CHM-based model. For the moist tropical forest on Barro Colorado Island, Panama, the models gave R2 ranging between 0.70 and 0.71 and RMSE between 30.08 (12.36%) and 30.32 (12.46) Mg ha-1 [between 0.69-0.70 and 30.42 (12.50%) and 61.30 (25.19%) Mg ha-1] for the echo-based [CHMbased] models. Finally, for the Atlantic forest in the Sierra do Mar, Brazil, R2 was between 0.58-0.69 and RMSE between 37.73 (8.67%) and 39.77 (9.14%) Mg ha-1 for the echo-based model, whereas for the CHM R2 was between 0.37-0.45 and RMSE between 45.43 (10.44%) and 67.23 (15.45%) Mg ha-1. Conclusions: Metrics derived from the CHM show a higher dependence on point density than metrics derived from the echo-based data model. Despite the median of the differences between metrics derived at different point densities differing significantly from zero, the mean change was close to zero and smaller than the standard deviation except for very low point densities (1 point m-2). The application of calibrated models to estimate AGB on metrics derived from thinned datasets resulted in less than 5% error when metrics were derived from the echo-based model. For CHM-based metrics, the same level of error was obtained for point densities higher than 5 points m-2. The fact that reducing point density does not introduce significant errors in AGB estimates is important for biomass monitoring and for an effective implementation of climate change mitigation policies such as REDD + due to its implications for the costs of data acquisition. Both data models showed similar capability to estimate AGB when point density was greater than or equal to 5 point m-2. © The Author(s) 2017."
"56539196700;6506383700;7102427465;7201656865;","Aerosol characterization and radiative properties over Kavaratti, a remote island in southern Arabian Sea from the period of observations",2017,"10.1016/j.scitotenv.2017.04.168","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018380174&doi=10.1016%2fj.scitotenv.2017.04.168&partnerID=40&md5=6074dedfbfeace49b24ad0de1d6b8382","Long-term measurements of spectral aerosol optical depth (AOD) using sun/sky radiometer for a period of five years (2009–2014) from the remote island location at Kavaratti (KVT; 10.56°N, 72.64°E) in the southern Arabian sea have been analysed. Climatologically, AODs decrease from October to reach maximum of ~ 0.6 (at 500 nm) in March, followed by a sudden fall towards May. Significant modulations of intra-seasonal timescales over this general pattern are noticed due to the changes in the relative strength of distinctively different sources. The corresponding changes in aerosol inversion parameters reveal the presence of coarse-mode aerosols during spring and fine-mode absorbing aerosols in autumn and winter months. An overall dominance of a mixed type of aerosols (~ 41%) with maximum in winter (~ 53%) was found via the AOD500 vs. Ångström exponent (α440–870) relationship, while biomass-burning aerosols or thick urban/industrial plumes contribute to ~ 19%. Spectral dependence of Ångström exponent and aerosol absorbing properties were used to identify the aerosol types and its modification processes. Based on air mass back trajectory analysis, we revealed that the advection of aerosols from Indian subcontinent and western regions plays a major role in modifying the optical properties of aerosols over the observational site. The shortwave aerosol direct radiative forcing estimated via SBDART model ranges from − 11.00 W m− 2 to − 7.38 W m− 2, − 21.51 W m− 2 to − 14.33 W m− 2 and 3.17 W m− 2 and 10.0 W m− 2 at top of atmosphere, surface and within the atmosphere, respectively. This atmospheric forcing translates into heating rate of 0.62–1.04 K day− 1. Furthermore, the vertical profiles of aerosols and heating rate exhibit significant increase in lower (during winter and autumn) and mid troposphere (during spring). This may cause serious climate implications over Kavaratti with further consequences on cloud microphysics and monsoon rainfall. © 2017 Elsevier B.V."
"7007021059;54893098900;7402064802;55366637500;55339081600;7202660824;7404142321;56014511300;8067118800;26645289600;","The Cloud Feedback Model Intercomparison Project (CFMIP) Diagnostic Codes Catalogue - Metrics, diagnostics and methodologies to evaluate, understand and improve the representation of clouds and cloud feedbacks in climate models",2017,"10.5194/gmd-10-4285-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85035353094&doi=10.5194%2fgmd-10-4285-2017&partnerID=40&md5=7f3bbfa2f5ec3aec4d9e75c63b8a3fe5","The CFMIP Diagnostic Codes Catalogue assembles cloud metrics, diagnostics and methodologies, together with programs to diagnose them from general circulation model (GCM) outputs written by various members of the CFMIP community. This aims to facilitate use of the diagnostics by the wider community studying climate and climate change. This paper describes the diagnostics and metrics which are currently in the catalogue, together with examples of their application to model evaluation studies and a summary of some of the insights these diagnostics have provided into the main shortcomings in current GCMs. Analysis of outputs from CFMIP and CMIP6 experiments will also be facilitated by the sharing of diagnostic codes via this catalogue.<br><br>Any code which implements diagnostics relevant to analysing clouds - including cloud-circulation interactions and the contribution of clouds to estimates of climate sensitivity in models - and which is documented in peer-reviewed studies, can be included in the catalogue. We very much welcome additional contributions to further support community analysis of CMIP6 outputs."
"57195591631;7403282069;8977001000;","The Response of Simulated Arctic Mixed-Phase Stratocumulus to Sea Ice Cover Variability in the Absence of Large-Scale Advection",2017,"10.1002/2017JD027086","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034739741&doi=10.1002%2f2017JD027086&partnerID=40&md5=7cd88bf649cb8f2fde86011ed9ae62d7","This study examines the responses of Arctic mixed-phase stratocumulus boundary layer to sea ice cover variability near the sea ice margins using large eddy simulations. The simulations are conducted for two different atmospheric conditions, based on observations from the Surface Heat Budget of the Arctic Ocean Experiment (SHEBA) (100% sea ice-covered) and the Mixed-Phase Arctic Cloud Experiment (M-PACE) (open ocean). The effect of sea ice cover variability is investigated for both atmospheric conditions by conducting a series of simulations prescribed with varying amounts of sea ice cover and no large-scale advection. As sea ice cover amount decreases, the SHEBA boundary layer deepens and becomes decoupled. The relative strength of turbulence driven by surface heating to that driven by cloud top radiative cooling increases. Cloud ice and snow grow more efficiently than cloud liquid with moisture transported from the lower boundary layer. On the other hand, as sea ice cover amount increases, the M-PACE boundary layer becomes shallower and more coupled with the surface as turbulence mainly driven by cloud top radiative cooling. Moisture supply from the surface is reduced, while cloud droplets are generated from turbulence at cloud top with little ice formation. In both atmospheric conditions, the boundary layer turbulence structure is modified according to change in the relative strength of boundary layer turbulent sources as sea ice amount changes, resulting in the growth/decay of the cloud layer. Simulations with smaller sea ice cover amounts are associated with more cloud ice but not necessarily more cloud liquid. ©2017. American Geophysical Union. All Rights Reserved."
"56461451000;7410221267;7402169131;16445036300;55703600300;37118895200;57197720958;55332214100;15135583300;","Improving Lightning and Precipitation Prediction of Severe Convection Using Lightning Data Assimilation With NCAR WRF-RTFDDA",2017,"10.1002/2017JD027340","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034094725&doi=10.1002%2f2017JD027340&partnerID=40&md5=9e85b40907fe6eb506fc47124654d57d","In this study, a lightning data assimilation (LDA) scheme was developed and implemented in the National Center for Atmospheric Research Weather Research and Forecasting-Real-Time Four-Dimensional Data Assimilation system. In this LDA method, graupel mixing ratio (qg) is retrieved from observed total lightning. To retrieve qg on model grid boxes, column-integrated graupel mass is first calculated using an observation-based linear formula between graupel mass and total lightning rate. Then the graupel mass is distributed vertically according to the empirical qg vertical profiles constructed from model simulations. Finally, a horizontal spread method is utilized to consider the existence of graupel in the adjacent regions of the lightning initiation locations. Based on the retrieved qg fields, latent heat is adjusted to account for the latent heat releases associated with the formation of the retrieved graupel and to promote convection at the observed lightning locations, which is conceptually similar to the method developed by Fierro et al. Three severe convection cases were studied to evaluate the LDA scheme for short-term (0–6 h) lightning and precipitation forecasts. The simulation results demonstrated that the LDA was effective in improving the short-term lightning and precipitation forecasts by improving the model simulation of the qg fields, updrafts, cold pool, and front locations. The improvements were most notable in the first 2 h, indicating a highly desired benefit of the LDA in lightning and convective precipitation nowcasting (0–2 h) applications. ©2017. American Geophysical Union. All Rights Reserved."
"56188306800;57197808707;7409080503;14018770700;8636990400;7406073187;55806891500;8953662800;8839875600;","Potential influences of neglecting aerosol effects on the NCEP GFS precipitation forecast",2017,"10.5194/acp-17-13967-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034969191&doi=10.5194%2facp-17-13967-2017&partnerID=40&md5=0eb1c7ef72fcadc6cad6d09f2309cdba","Aerosol-cloud interactions (ACIs) have been widely recognized as a factor affecting precipitation. However, they have not been considered in the operational National Centers for Environmental Predictions Global Forecast System model. We evaluated the potential impact of neglecting ACI on the operational rainfall forecast using ground-based and satellite observations and model reanalysis. The Climate Prediction Center unified gauge-based precipitation analysis and the Modern-Era Retrospective analysis for Research and Applications Version 2 aerosol reanalysis were used to evaluate the forecast in three countries for the year 2015. The overestimation of light rain (47.84 %) and underestimation of heavier rain (31.83, 52.94, and 65.74 % for moderate rain, heavy rain, and very heavy rain, respectively) from the model are qualitatively consistent with the potential errors arising from not accounting for ACI, although other factors cannot be totally ruled out. The standard deviation of the forecast bias was significantly correlated with aerosol optical depth in Australia, the US, and China. To gain further insight, we chose the province of Fujian in China to pursue a more insightful investigation using a suite of variables from gauge-based observations of precipitation, visibility, water vapor, convective available potential energy (CAPE), and satellite datasets. Similar forecast biases were found: over-forecasted light rain and under-forecasted heavy rain. Long-term analyses revealed an increasing trend in heavy rain in summer and a decreasing trend in light rain in other seasons, accompanied by a decreasing trend in visibility, no trend in water vapor, and a slight increasing trend in summertime CAPE. More aerosols decreased cloud effective radii for cases where the liquid water path was greater than 100 g m-2. All findings are consistent with the effects of ACI, i.e., where aerosols inhibit the development of shallow liquid clouds and invigorate warm-base mixed-phase clouds (especially in summertime), which in turn affects precipitation. While we cannot establish rigorous causal relations based on the analyses presented in this study, the significant rainfall forecast bias seen in operational weather forecast model simulations warrants consideration in future model improvements."
"57218665706;56009939800;57143339000;57141036900;57196196926;7102242979;56926959900;12778343700;57197812842;57190246562;7501863198;35485055800;7103200508;23017545300;","Insight into the in-cloud formation of oxalate based on in situ measurement by single particle mass spectrometry",2017,"10.5194/acp-17-13891-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85035039508&doi=10.5194%2facp-17-13891-2017&partnerID=40&md5=e91a5c4984d1d2361803cda8baf72d19","While ground-based works suggest the significance of in-cloud production (or aqueous formation) to oxalate, direct evidence is rare. With the in situ measurements performed at a remote mountain site (1690mabove sea level) in southern China, we first reported the size-resolved mixing state of oxalate in the cloud droplet residual (cloud RES), the cloud interstitial (cloud INT), and ambient (cloud-free) particles by single particle mass spectrometry. The results support the growing evidence that in-cloud aqueous reactions promote the formation of oxalate, with ∼ 15% of the cloud RES and cloud INT particles containing oxalate in contrast to only ∼ 5% of the cloud-free particles. Furthermore, individual particle analysis provides unique insight into the formation of oxalate during in-cloud processing. Oxalate was predominantly (>70% in number) internally mixed with the aged biomass-burning particles, highlighting the impact of biomass burning on the formation of oxalate. In contrast, oxalate was underrepresented in aged elemental carbon particles, although they represented the largest fraction of the detected particles. It can be interpreted by the individual particle mixing state that the aged biomass-burning particles contained an abundance of organic components serving as precursors for oxalate. Through the analysis of the relationship between oxalate and organic acids (-45[HCO2]-, -59[CH3CO2]-, -71[C2H3CO2]-, -73[C2HO3]-), the results show that in-cloud aqueous reactions dramatically improved the conversion of organic acids to oxalate. The abundance of glyoxylate associated with the aged biomass-burning particles is a controlling factor for the in-cloud production of oxalate. Since only limited information on oxalate is available in the free troposphere, the results also provide an important reference for future understanding of the abundance, evolution, and climate impacts of oxalate."
"55355176000;8067118800;50261552200;35329672300;10243650000;8918407000;35227762400;","A Multimodel Study on Warm Precipitation Biases in Global Models Compared to Satellite Observations",2017,"10.1002/2017JD027310","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033595784&doi=10.1002%2f2017JD027310&partnerID=40&md5=013e410290876f5e5414acfa0f072987","The cloud-to-precipitation transition process in warm clouds simulated by state-of-the-art global climate models (GCMs), including both traditional climate models and a high-resolution model, is evaluated against A-Train satellite observations. The models and satellite observations are compared in the form of the statistics obtained from combined analysis of multiple-satellite observables that probe signatures of the cloud-to-precipitation transition process. One common problem identified among these models is the too-frequent occurrence of warm precipitation. The precipitation is found to form when the cloud particle size and the liquid water path (LWP) are both much smaller than those in observations. The too-efficient formation of precipitation is found to be compensated for by errors of cloud microphysical properties, such as underestimated cloud particle size and LWP, to an extent that varies among the models. However, this does not completely cancel the precipitation formation bias. Robust errors are also found in the evolution of cloud microphysical properties from nonprecipitating to drizzling and then to raining clouds in some GCMs, implying unrealistic interaction between precipitation and cloud water. Nevertheless, auspicious information is found for future improvement of warm precipitation representations: the adoption of more realistic autoconversion scheme in the high-resolution model improves the triggering of precipitation, and the introduction of a sophisticated subgrid variability scheme in a traditional model improves the simulated precipitation frequency over subtropical eastern ocean. However, deterioration in other warm precipitation characteristics is also found accompanying these improvements, implying the multisource nature of warm precipitation biases in GCMs. ©2017. American Geophysical Union. All Rights Reserved."
"56246453200;24722339600;25640569400;","Identifying Meteorological Controls on Open and Closed Mesoscale Cellular Convection Associated with Marine Cold Air Outbreaks",2017,"10.1002/2017JD027031","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032882868&doi=10.1002%2f2017JD027031&partnerID=40&md5=631fa8486c2b50b8d8929767bcdb374a","Mesoscale cellular convective (MCC) clouds occur in large-scale patterns over the ocean and have important radiative effects on the climate system. An examination of time-varying meteorological conditions associated with satellite-observed open and closed MCC clouds is conducted to illustrate the influence of large-scale meteorological conditions. Marine cold air outbreaks (MCAO) influence the development of open MCC clouds and the transition from closed to open MCC clouds. MCC neural network classifications on Moderate Resolution Imaging Spectroradiometer (MODIS) data for 2008 are collocated with Clouds and the Earth's Radiant Energy System (CERES) data and ERA-Interim reanalysis to determine the radiative effects of MCC clouds and their thermodynamic environments. Closed MCC clouds are found to have much higher albedo on average than open MCC clouds for the same cloud fraction. Three meteorological control metrics are tested: sea-air temperature difference (ΔT), estimated inversion strength (EIS), and a MCAO index (M). These predictive metrics illustrate the importance of atmospheric surface forcing and static stability for open and closed MCC cloud formation. Predictive sigmoidal relations are found between M and MCC cloud frequency globally and regionally: negative for closed MCC cloud and positive for open MCC cloud. The open MCC cloud seasonal cycle is well correlated with M, while the seasonality of closed MCC clouds is well correlated with M in the midlatitudes and EIS in the tropics and subtropics. M is found to best distinguish open and closed MCC clouds on average over shorter time scales. The possibility of a MCC cloud feedback is discussed. ©2017. American Geophysical Union. All Rights Reserved."
"24472400800;6602988199;7003777747;35547807400;36894599500;24329376600;57203200427;12240390300;56250250300;57189524073;7006462819;12139043600;7102976560;6602414959;57109884900;57196261945;7004214645;57191980050;7202079615;22986631300;","Rapid Adjustments Cause Weak Surface Temperature Response to Increased Black Carbon Concentrations",2017,"10.1002/2017JD027326","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037688178&doi=10.1002%2f2017JD027326&partnerID=40&md5=7f81a3d3948c6e7099fbd1aafacc0481","We investigate the climate response to increased concentrations of black carbon (BC), as part of the Precipitation Driver Response Model Intercomparison Project (PDRMIP). A tenfold increase in BC is simulated by nine global coupled-climate models, producing a model median effective radiative forcing of 0.82 (ranging from 0.41 to 2.91) W m−2, and a warming of 0.67 (0.16 to 1.66) K globally and 1.24 (0.26 to 4.31) K in the Arctic. A strong positive instantaneous radiative forcing (median of 2.10 W m−2 based on five of the models) is countered by negative rapid adjustments (−0.64 W m−2 for the same five models), which dampen the total surface temperature signal. Unlike other drivers of climate change, the response of temperature and cloud profiles to the BC forcing is dominated by rapid adjustments. Low-level cloud amounts increase for all models, while higher-level clouds are diminished. The rapid temperature response is particularly strong above 400 hPa, where increased atmospheric stabilization and reduced cloud cover contrast the response pattern of the other drivers. In conclusion, we find that this substantial increase in BC concentrations does have considerable impacts on important aspects of the climate system. However, some of these effects tend to offset one another, leaving a relatively small median global warming of 0.47 K per W m−2—about 20% lower than the response to a doubling of CO2. Translating the tenfold increase in BC to the present-day impact of anthropogenic BC (given the emissions used in this work) would leave a warming of merely 0.07 K. ©2017. The Authors."
"56766263400;7003548068;24315205000;7402264077;","Discrepancies in the Climatology and Trends of Cloud Cover in Global and Regional Climate Models for the Mediterranean Region",2017,"10.1002/2017JD027147","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037684751&doi=10.1002%2f2017JD027147&partnerID=40&md5=7fd13813f88357a7c0a0f512fd3b251f","The present study aims at comparing total cloud cover (TCC) as simulated by regional climate models (RCM) from CORDEX project with the same variable as simulated by the driving global climate models (GCM), which are part of the fifth phase of the Climate Model Intercomparison Project ensemble. The comparison is performed for the Mediterranean region, and for the 1971–2005 period, when results from the “historical” scenario can also be compared with two data sets of ground-based cloud observations. We work with 14 modeling results (resolution, 0.11° × 0.11°), which are a combination of five GCMs and five RCMs. In general, RCMs improve only very slightly the climatic estimation of TCC when compared with observations. Indeed, not all RCMs behave the same, and some indicators (monthly evolution of the relative bias) show an enhancement, while other indices (overall mean bias and annual range difference) improve only very slightly with respect to GCMs. Changes in the estimate of TCC in summer might be the most relevant value added by RCMs, as these should describe in a more proper way several mesoscale processes, which play a more relevant role in summer. Noticeably, RCMs are unable to capture the observed decadal trend in TCC. Thus, TCC simulated by RCMs is almost stable, in contradiction with observations and GCMs, which both show statistically significant decreasing trends in the Mediterranean area. This result is somewhat unsatisfactory, as if RCMs cannot reproduce past trends in TCC, their skill in projecting TCC into the future may be questioned. ©2017. American Geophysical Union. All Rights Reserved."
"16403452000;7005184190;35585284200;13403526200;57203488770;16029719200;","A Model and Satellite-Based Analysis of the Tropospheric Ozone Distribution in Clear Versus Convectively Cloudy Conditions",2017,"10.1002/2017JD027015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037715987&doi=10.1002%2f2017JD027015&partnerID=40&md5=497b2cb458d13fffd930f09f2c368d37","Satellite observations of in-cloud ozone concentrations from the Ozone Monitoring Instrument and Microwave Limb Sounder instruments show substantial differences from background ozone concentrations. We develop a method for comparing a free-running chemistry-climate model (CCM) to in-cloud and background ozone observations using a simple criterion based on cloud fraction to separate cloudy and clear-sky days. We demonstrate that the CCM simulates key features of the in-cloud versus background ozone differences and of the geographic distribution of in-cloud ozone. Since the agreement is not dependent on matching the meteorological conditions of a specific day, this is a promising method for diagnosing how accurately CCMs represent the relationships between ozone and clouds, including the lower ozone concentrations shown by in-cloud satellite observations. Since clouds are associated with convection as well as changes in chemistry, we diagnose the tendency of tropical ozone at 400 hPa due to chemistry, convection and turbulence, and large-scale dynamics. While convection acts to reduce ozone concentrations at 400 hPa throughout much of the tropics, it has the opposite effect over highly polluted regions of South and East Asia. ©2017. American Geophysical Union. All Rights Reserved."
"57203200427;57195619091;7003777747;","Quasi-Additivity of the Radiative Effects of Marine Cloud Brightening and Stratospheric Sulfate Aerosol Injection",2017,"10.1002/2017GL074647","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032979715&doi=10.1002%2f2017GL074647&partnerID=40&md5=cf25ea31be4fae065dcaa4392e643771","Stratospheric sulfate aerosol injection (SAI) and marine cloud brightening (MCB) are the two most studied solar radiation management techniques. For the first time we combine them in a climate model to investigate their complementarity in terms of both instantaneous and effective radiative forcings. The effective radiative forcing induced by SAI is significantly stronger than its instantaneous counterpart evaluated at the top of atmosphere. Radiative kernel calculations indicate that this occurs because of a significant stratospheric warming and despite a large increase in stratospheric water vapor that strengthens the greenhouse effect. There is also a large decrease in high-level cloudiness induced by a stratification of the upper tropopause. Our model experiments also show that the radiative effects of SAI and MCB are quasi-additive and have fairly complementary patterns in the Tropics. This results in less spatial and temporal variability in the radiative forcing for combined SAI and MCB as compared to MCB alone. ©2017. American Geophysical Union. All Rights Reserved."
"57192307391;12794036300;57209630149;7501793055;57117051600;57196420659;57192314234;","Distribution and Variability of Satellite-Derived Signals of Isolated Convection Initiation Events Over Central Eastern China",2017,"10.1002/2017JD026946","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032952502&doi=10.1002%2f2017JD026946&partnerID=40&md5=aa1e05296e3f0b7d34c4eaa3627f865a","This study combined measurements from the Chinese operational geostationary satellite Fengyun-2E (FY-2E) and ground-based weather radars to conduct a statistical survey of isolated convection initiation (CI) over central eastern China (CEC). The convective environment in CEC is modulated by the complex topography and monsoon climate. From May to August 2010, a total of 1,630 isolated CI signals were derived from FY-2E using a semiautomated method. The formation of these satellite-derived CI signals peaks in the early afternoon and occurs with high frequency in areas with remarkable terrain inhomogeneity (e.g., mountain, water, and mountain-water areas). The high signal frequency areas shift from northwest CEC (dry, high altitude) in early summer to southeast CEC (humid, low altitude) in midsummer along with an increasing monthly mean frequency. The satellite-derived CI signals tend to have longer lead times (the time difference between satellite-derived signal formation and radar-based CI) in the late morning and afternoon than in the early morning and night. During the early morning and night, the distinction between cloud top signatures and background terrestrial radiation becomes less apparent, resulting in delayed identification of the signals and thus short and even negative lead times. A decline in the lead time is observed from May to August, likely due to the increasing cloud growth rate and warm-rain processes. Results show increasing lead times with increasing landscape elevation, likely due to more warm-rain processes over the coastal sea and plain, along with a decreasing cloud growth rate from hill and mountain to the plateau. ©2017. American Geophysical Union. All Rights Reserved."
"56779807500;56284543100;56379892200;","Synoptic Control of Contrail Cirrus Life Cycles and Their Modification Due to Reduced Soot Number Emissions",2017,"10.1002/2017JD027011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033579166&doi=10.1002%2f2017JD027011&partnerID=40&md5=b654377845558db125b4b9cb95452e0f","The atmospheric state, aircraft emissions, and engine properties determine formation and initial properties of contrails. The synoptic situation controls microphysical and dynamical processes and causes a wide variability of contrail cirrus life cycles. A reduction of soot particle number emissions, resulting, for example, from the use of alternative fuels, strongly impacts initial ice crystal numbers and microphysical process rates of contrail cirrus. We use the European Centre/Hamburg (ECHAM) climate model version 5 including a contrail cirrus modul, studying process rates, properties, and life cycles of contrail cirrus clusters within different synoptic situations. The impact of reduced soot number emissions is approximated by a reduction in the initial ice crystal number, exemplarily studied for 80%. Contrail cirrus microphysical and macrophysical properties can depend much more strongly on the synoptic situation than on the initial ice crystal number. They can attain a large cover, optical depth, and ice water content in long-lived and large-scale ice-supersaturated areas, making them particularly climate-relevant. In those synoptic situations, the accumulated ice crystal loss due to sedimentation is increased by around 15% and the volume of contrail cirrus, exceeding an optical depth of 0.02, and their short-wave radiative impact are strongly decreased due to reduced soot emissions. These reductions are of little consequence in short-lived and small-scale ice-supersaturated areas, where contrail cirrus stay optically very thin and attain a low cover. The synoptic situations in which long-lived and climate-relevant contrail cirrus clusters can be found over the eastern U.S. occur in around 25% of cases. ©2017. American Geophysical Union. All Rights Reserved."
"42462407100;56604618200;6701511321;7005453641;35472747700;7201488063;49261186800;26533129200;37761600900;10141883400;35768617200;55272324200;23568896200;55777759900;56016103100;56479206800;","Observing the Impact of Calbuco Volcanic Aerosols on South Polar Ozone Depletion in 2015",2017,"10.1002/2017JD026987","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032984917&doi=10.1002%2f2017JD026987&partnerID=40&md5=1e2311378042a67d4c3d0bde9cb55522","The Southern Hemisphere Antarctic stratosphere experienced two noteworthy events in 2015: a significant injection of sulfur from the Calbuco volcanic eruption in Chile in April and a record-large Antarctic ozone hole in October and November. Here we quantify Calbuco's influence on stratospheric ozone depletion in austral spring 2015 using observations and an Earth system model. We analyze ozonesondes, as well as data from the Microwave Limb Sounder. We employ the Community Earth System Model, version 1, with the Whole Atmosphere Community Climate Model (WACCM) in a specified dynamics setup, which includes calculations of volcanic effects. The Cloud-Aerosol Lidar with Orthogonal Polarization data indicate enhanced volcanic liquid sulfate 532 nm backscatter values as far poleward as 68°S during October and November (in broad agreement with WACCM). Comparison of the location of the enhanced aerosols to ozone data supports the view that aerosols played a major role in increasing the ozone hole size, especially at pressure levels between 150 and 100 hPa. Ozonesonde vertical ozone profiles from the sites of Syowa, South Pole, and Neumayer display the lowest individual October or November measurements at 150 hPa since the 1991 Mount Pinatubo eruption period, with Davis showing similarly low values, but no available 1990 data. The analysis suggests that under the cold conditions ideal for ozone depletion, stratospheric volcanic aerosol particles from the moderate-magnitude eruption of Calbuco in 2015 greatly enhanced austral ozone depletion, particularly at 55–68°S, where liquid binary sulfate aerosols have a large influence on ozone concentrations. ©2017. American Geophysical Union. All Rights Reserved."
"55540820600;8316151600;57211565887;55187246200;55683372600;57197762450;15071249200;24722810700;30967617500;7201770023;7004239407;55884227800;7005022197;56037741700;7402886703;","Overview and preliminary results of the Surface Ocean Aerosol Production (SOAP) campaign",2017,"10.5194/acp-17-13645-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034620014&doi=10.5194%2facp-17-13645-2017&partnerID=40&md5=54446f1aab93acccf564f745447a9c4c","Establishing the relationship between marine boundary layer (MBL) aerosols and surface water biogeochemistry is required to understand aerosol and cloud production processes over the remote ocean and represent them more accurately in earth system models and global climate projections. This was addressed by the SOAP (Surface Ocean Aerosol Production) campaign, which examined air.sea interaction over biologically productive frontal waters east of New Zealand. This overview details the objectives, regional context, sampling strategy and provisional findings of a pilot study, PreSOAP, in austral summer 2011 and the following SOAP voyage in late austral summer 2012. Both voyages characterized surface water and MBL composition in three phytoplankton blooms of differing species composition and biogeochemistry, with significant regional correlation observed between chlorophyll a and DMSsw. Surface seawater dimethylsulfide (DMSsw) and associated air.sea DMS flux showed spatial variation during the SOAP voyage, with maxima of 25 nmol L-1 and 100 molm-2 d-1, respectively, recorded in a dinoflagellate bloom. Inclusion of SOAP data in a regional DMSsw compilation indicates that the current climatological mean is an underestimate for this region of the southwest Pacific. Estimation of the DMS gas transfer velocity (kDMS/by independent techniques of eddy covariance and gradient flux showed good agreement, although both exhibited periodic deviations from model estimates. Flux anomalies were related to surface warming and sea surface microlayer enrichment and also reflected the heterogeneous distribution of DMSsw and the associated flux footprint. Other aerosol precursors measured included the halides and various volatile organic carbon compounds, with first measurements of the short-lived gases glyoxal and methylglyoxal in pristine Southern Ocean marine air indicating an unidentified local source. The application of a real-time clean sector, contaminant markers and a common aerosol inlet facilitated multi-sensor measurement of uncontaminated air. Aerosol characterization identified variable Aitken mode and consistent submicron-sized accumulation and coarse modes. Submicron aerosol mass was dominated by secondary particles containing ammonium sulfate/bisulfate under light winds, with an increase in sea salt under higher wind speeds. MBL measurements and chamber experiments identified a significant organic component in primary and secondary aerosols. Comparison of SOAP aerosol number and size distributions reveals an underprediction in GLOMAP (GLObal Model of Aerosol Processes)-mode aerosol number in clean marine air masses, suggesting a missing marine aerosol source in the model. The SOAP data will be further examined for evidence of nucleation events and also to identify relationships between MBL composition and surface ocean biogeochemistry that may provide potential proxies for aerosol precursors and production."
"7004384155;36945003900;57193694921;55869652000;","Cloud climatologies from the infrared sounders AIRS and IASI: Strengths and applications",2017,"10.5194/acp-17-13625-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034430962&doi=10.5194%2facp-17-13625-2017&partnerID=40&md5=0e4caa9761dc3afbe46e2a31515a6847","Global cloud climatologies have been built from 13 years of Atmospheric Infrared Sounder (AIRS) and 8 years of Infrared Atmospheric Sounding Interferometer (IASI) observations, using an updated Clouds from Infrared Sounders (CIRS) retrieval. The CIRS software can handle any infrared (IR) sounder data. Compared to the original retrieval, it uses improved radiative transfer modelling, accounts for atmospheric spectral transmissivity changes associated with CO2 concentration and incorporates the latest ancillary data (atmospheric profiles, surface temperature and emissivities). The global cloud amount is estimated to be 0.67-0.70, for clouds with IR optical depth larger than about 0.1. The spread of 0.03 is associated with ancillary data. Cloud amount is partitioned into about 40 % high-level clouds, 40 % low-level clouds and 20 % mid-level clouds. The latter two categories are only detected in the absence of upper clouds. The A-Train active instruments, lidar and radar of the CALIPSO and CloudSat missions, provide a unique opportunity to evaluate the retrieved AIRS cloud properties. CIRS cloud height can be approximated either by the mean layer height (for optically thin clouds) or by the mean between cloud top and the height at which the cloud reaches opacity. This is valid for high-level as well as for low-level clouds identified by CIRS. IR sounders are particularly advantageous to retrieve upper-tropospheric cloud properties, with a reliable cirrus identification, day and night. These clouds are most abundant in the tropics, where high opaque clouds make up 7.5 %, thick cirrus 27.5 % and thin cirrus about 21.5 % of all clouds. The 5 % annual mean excess in high-level cloud amount in the Northern compared to the Southern Hemisphere has a pronounced seasonal cycle with a maximum of 25 % in boreal summer, in accordance with the moving of the ITCZ peak latitude, with annual mean of 4° N, to a maximum of 12° N. This suggests that this excess is mainly determined by the position of the ITCZ. Considering interannual variability, tropical cirrus are more frequent relative to all clouds when the global (or tropical) mean surface gets warmer. Changes in relative amount of tropical high opaque and thin cirrus with respect to mean surface temperature show different geographical patterns, suggesting that their response to climate change might differ. © 2017 Author(s)."
"57196348092;6603779272;18437230800;7003311618;","Aerosol trends as a potential driver of regional climate in the central United States: Evidence from observations",2017,"10.5194/acp-17-13559-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034017636&doi=10.5194%2facp-17-13559-2017&partnerID=40&md5=6742dfe1070b099a1a2fffe7baa9782e","In situ surface observations show that downward surface solar radiation (SWdn) over the central and southeastern United States (US) has increased by 0.58-1.0Wm-2a-1 over the 2000-2014 time frame, simultaneously with reductions in US aerosol optical depth (AOD) of 3.3-5.0 × 10-3a-1. Establishing a link between these two trends, however, is challenging due to complex interactions between aerosols, clouds, and radiation. Here we investigate the clear-sky aerosol-radiation effects of decreasing US aerosols on SWdn and other surface variables by applying a one-dimensional radiative transfer to 2000-2014 measurements of AOD at two Surface Radiation Budget Network (SURFRAD) sites in the central and southeastern United States. Observations characterized as ""clear-sky"" may in fact include the effects of thin cirrus clouds, and we consider these effects by imposing satellite data from the Clouds and Earth's Radiant Energy System (CERES) into the radiative transfer model. The model predicts that 2000-2014 trends in aerosols may have driven clear-sky SWdn trends of +1.35Wm-2a-1 at Goodwin Creek, MS, and +0.93Wm-2a-1 at Bondville, IL. While these results are consistent in sign with observed trends, a cross-validated multivariate regression analysis shows that AOD reproduces 20-26% of the seasonal (June-September, JJAS) variability in clear-sky direct and diffuse SWdn at Bondville, IL, but none of the JJAS variability at Goodwin Creek, MS. Using in situ soil and surface flux measurements from the Ameriflux network and Illinois Climate Network (ICN) together with assimilated meteorology from the North American Land Data Assimilation System (NLDAS), we find that sunnier summers tend to coincide with increased surface air temperature and soil moisture deficits in the central US. The 1990-2015 trends in the NLDAS SWdn over the central US are also of a similar magnitude to our modeled 2000-2014 clear-sky trends. Taken together, these results suggest that climate and regional hydrology in the central US are sensitive to the recent reductions in aerosol concentrations. Our work has implications for severely polluted regions outside the US, where improvements in air quality due to reductions in the aerosol burden could inadvertently pose an enhanced climate risk. © Author(s) 2017."
"55081793600;36660575800;7004974000;57194335593;7003287989;56003449400;55962164400;","Sensitivity of AGCM-simulated regional JJAS precipitation to different convective parameterization schemes",2017,"10.1002/joc.5108","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019678813&doi=10.1002%2fjoc.5108&partnerID=40&md5=d4938bd7f0bcc0b6e4faea6f4ac654ac","This study examines the effects of convective parameterization schemes (CPSs) on the simulated June–September (JJAS) precipitation climatology, variability and predictability over southwestern Arabian Peninsula and northeast Africa during 1981–2014 within an atmospheric global climate model framework. The three CPSs used are: the simplified Arakawa–Schubert (SAS) scheme; the SAS scheme with Tokioka modification (STOK) and the Emanuel (EMAN) scheme coupled with a probability distribution function-based cloud parameterization scheme. SAS and STOK overestimate JJAS total precipitation over the selected domain compared to observations, while EMAN underestimates. EMAN provides the most realistic distribution of precipitation and spatial distribution of convective precipitation despite the tendency for underestimating the total precipitation. The principal patterns of precipitation variability (as measured by the leading empirical orthogonal functions) in EMAN and STOK are clearly related to the observed pattern, while the maximum variability in SAS occurs in a completely different location. The El Niño Southern Oscillation-related JJAS precipitation teleconnection simulated by the SAS scheme is very weak as compared to observations and other two CPSs. The signal-to-noise ratio estimated by SAS and STOK is very low as compared to EMAN. Correlation analysis shows that EMAN performs better than the other two CPSs. Low (high) outgoing longwave radiation (OLR) values are indicative of enhanced (suppressed) convection and hence more (less) cloud coverage. The root mean square error estimated for OLR in EMAN is lower than that of the other two CPSs. The vertical structure of specific humidity and temperature shows less error in EMAN than that of the other two CPSs, which could be a reason for better predictability over the region of interest. © 2017 Royal Meteorological Society"
"41261775400;7006685850;35503593800;55342453700;","Performance evaluation of land surface models and cumulus convection schemes in the simulation of Indian summer monsoon using a regional climate model",2017,"10.1016/j.atmosres.2017.06.023","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021241369&doi=10.1016%2fj.atmosres.2017.06.023&partnerID=40&md5=38959580e17f384ccc4e4725e4508825","In this study, an attempt has been made to investigate the sensitivity of land surface models (LSM) and cumulus convection schemes (CCS) using a regional climate model, RegCM Version-4.1 in simulating the Indian Summer Monsoon (ISM). Numerical experiments were conducted in seasonal scale (May–September) for three consecutive years: 2007, 2008, 2009 with two LSMs (Biosphere Atmosphere Transfer Scheme (BATS), Community Land Model (CLM 3.5) and five CCSs (MIT, KUO, GRELL, GRELL over land and MIT over ocean (GL_MO), GRELL over ocean and MIT over land (GO_ML)). Important synoptic features are validated using various reanalysis datasets and satellite derived products from TRMM and CRU data. Seasonally averaged surface temperature is reasonably well simulated by the model using both the LSMs along with CCSs namely, MIT, GO_ML and GL_MO schemes. Model simulations reveal slight warm bias using these schemes whereas significant cold bias is seen with KUO and GRELL schemes during all three years. It is noticed that the simulated Somali Jet (SJ) is weak in all simulations except MIT scheme in the simulations with (both BATS and CLM) in which the strength of SJ reasonably well captured. Although the model is able to simulate the Tropical Easterly Jet (TEJ) and Sub-Tropical Westerly Jet (STWJ) with all the CCSs in terms of their location and strength, the performance of MIT scheme seems to be better than the rest of the CCSs. Seasonal rainfall is not well simulated by the model. Significant underestimation of Indian Summer Monsoon Rainfall (ISMR) is observed over Central and North West India. Spatial distribution of seasonal ISMR is comparatively better simulated by the model with MIT followed by GO_ML scheme in combination with CLM although it overestimates rainfall over heavy precipitation zones. On overall statistical analysis, it is noticed that RegCM4 shows better skill in simulating ISM with MIT scheme using CLM. © 2017 Elsevier B.V."
"57199223787;57193840197;6506383700;57203774491;57207335291;","Source region and sector contributions of atmospheric soot particle in a coalfield region of Dhanbad, eastern part of India",2017,"10.1016/j.atmosres.2017.07.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026771565&doi=10.1016%2fj.atmosres.2017.07.020&partnerID=40&md5=27a80c12130a93b9932b1f583c6439e6","Black carbon (BC) aerosols affect the Earth's climate directly by interacting with the solar radiation and indirectly by modifying the lifetime and optical properties of clouds. However, our understanding of BC aerosols and their impacts on the climate are limited by lack of in situ measurements of BC, especially in the developing world. This study reports measurements of BC from Dhanbad, a coalfields area of eastern India, we analyze BC data at 370 and 880 nm during 2013 to gain insight into the emission sources affecting the study area. Our analysis indicates significantly higher absorption at the lower wavelength (ultraviolet). We estimate that ~ 33% of BC at Dhanbad comes from biomass/biofuel combustion and the remaining 67% from the fossil fuel combustion. Higher concentrations of BC370 nm (&gt; 12 μg m− 3) were observed when the air masses affecting Dhanbad originated far away in countries like Iran, Afghanistan, Pakistan, Oman, United Arab Emirates and passed over the Indo-Gangetic Plains (IGP) prior to arriving at the observation site. The source regions affecting BC880 nm were localized over the IGP but BC880 nm concentrations are 33% lower (~ 8 μg m− 3) than BC370 nm. The cluster analysis showed that the largest fraction (35 and 29%) of the air masses arriving at Dhanbad passed through the boundary layer of the central IGP and north-west IGP region during the post-monsoon season. Average values of BC370 nm (16.0 and 20.0 μg m− 3) and BC880 nm (9.5 and 10.0 μg m− 3) in the IGP influenced air masses were significantly higher than those arriving from other source regions. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) model were applied to understand the relative importance of different sources affecting Dhanbad. The variability of observed BC mass concentrations was captured fairly well by WRF-Chem with minor deviations from the measured values. Model results indicate that anthropogenic emissions account for more than 75% of the surface BC at Dhanbad. Biomass burning contribution peaks in March–April and October–November but remains less than 25%. Long-range transport estimated in terms of inflow from domain boundaries does not affect BC concentrations at Dhanbad significantly. © 2017"
"57132509000;23003259600;55495632500;57189378782;57216168952;16481561000;57131646800;57191334192;56375286600;55689034100;56068376200;","Evaluation of radiosonde, MODIS-NIR-Clear, and AERONET precipitable water vapor using IGS ground-based GPS measurements over China",2017,"10.1016/j.atmosres.2017.07.021","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026861405&doi=10.1016%2fj.atmosres.2017.07.021&partnerID=40&md5=7f1d0032e1b1059aea5a8f13c03a9031","Water vapor is one of the major greenhouse gases in the atmosphere and also the key parameter affecting the hydrological cycle, aerosol properties, aerosol-cloud interactions, the energy budget, and the climate. This study analyzed the temporal and spatial distribution of precipitable water vapor (PWV) in China using MODerate resolution Imaging Spectroradiometer near-infrared (MODIS-NIR)-Clear PWV products from 2011 to 2013. We then compared the four PWV products (Global Positioning System PWV (GPS-PWV), radiosonde PWV (RS-PWV), MODIS-NIR-Clear PWV, and Aerosol Robotic Network sunphotometer PWV (AERONET-PWV)) at six typical sites in China from 2011 to 2013. The analysis of the temporal and spatial distribution showed that the PWV distribution in China has clear geographical differences, and its basic distribution characteristics gradually change from the coast in the southeast to inland in the northwest. Affected by the East Asian monsoon, the PWV over China showed clear seasonal distribution features, with highest values in the summer, followed by autumn and spring, and the lowest values in winter. Intercomparison results showed that GPS-PWV and RS-PWV had a slightly higher correlation (R2 = 0.975) at 0000 UTC than that at 1200 UTC (R2 = 0.967). The mean values of Bias, SD, and RMSE between GPS-PWV and RS-PWV (GPS-RS) were − 0.03 mm, 2.36 mm, and 2.60 mm at 0000 UTC, and − 0.23 mm, 2.76 mm, and 2.95 mm at 1200 UTC, respectively. This showed that GPS-PWV was slightly lower than RS-PWV, and this difference was more obvious during the nighttime. The MODIS-NIR-Clear PWV product showed a similar correlation coefficient (R2 = 0.88) with GPS-PWV compared with RS-PWV. In addition, MODIS-NIR-Clear PWV was greater than GPS-PWV and RS-PWV. The MODIS-NIR-Clear PWV showed a larger deviation from GPS-PWV (MODIS-GPS Bias = 1.50 mm, RMSE = 5.76 mm) compared with RS PWV (MODIS-RS Bias = 0.75 mm, RMSE = 5.31 mm). The correlation coefficients between AERONET-PWV and the PWV from GPS, RS, and MODIS-NIR-Clear were 0.970, 0.963, and 0.923 (with RMSE of 2.53 mm, 3.67 mm, and 4.39 mm), respectively. In the Beijing area, the overall mean bias of the AERONET-PWV product with GPS-PWV, RS-PWV and MODIS-NIR-Clear PWV was − 0.09 mm, − 1.82 mm, and − 1.54 mm, respectively, which shows that the AERONET-PWV product was lower than the other three PWV products. © 2017 Elsevier B.V."
"57197361526;7004293205;7201689616;55001699000;44561538400;57219827799;55787886000;57196823996;6701796926;7202489497;","Depolarization calibration and measurements using the CANDAC Rayleigh-Mie-Raman lidar at Eureka, Canada",2017,"10.5194/amt-10-4253-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034018634&doi=10.5194%2famt-10-4253-2017&partnerID=40&md5=1b38dfafc93106227fd4931dd3f8a760","The Canadian Network for the Detection of Atmospheric Change (CANDAC) Rayleigh-Mie-Raman lidar (CRL) at Eureka, Nunavut, has measured tropospheric clouds, aerosols, and water vapour since 2007. In remote and meteorologically significant locations, such as the Canadian High Arctic, the ability to add new measurement capability to an existing well-tested facility is extremely valuable. In 2010, linear depolarization 532 nm measurement hardware was installed in the lidar's receiver. To minimize disruption in the existing lidar channels and to preserve their existing characterization so far as is possible, the depolarization hardware was placed near the end of the receiver cascade. The upstream optics already in place were not optimized for preserving the polarization of received light. Calibrations and Mueller matrix calculations are used to determine and mitigate the contribution of these upstream optics on the depolarization measurements. The results show that with appropriate calibration, indications of cloud particle phase (ice vs. water) through the use of the depolarization parameter are now possible to a precision of ±0.05 absolute uncertainty (≤ 10% relative uncertainty) within clouds at time and altitude resolutions of 5 min and 37.5 m respectively, with higher precision and higher resolution possible in select cases. The uncertainty is somewhat larger outside of clouds at the same altitude, typically with absolute uncertainty ≤ 0.1. Monitoring changes in Arctic cloud composition, including particle phase, is essential for an improved understanding of the changing climate locally and globally. © 2017 The Author(s)."
"57197751446;7005137442;","Linking the Climate and Thermal Phase Curve of 55 Cancri e",2017,"10.3847/1538-4357/aa9328","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034441041&doi=10.3847%2f1538-4357%2faa9328&partnerID=40&md5=e6b34376af3888ecf166196b8a55ecbd","The thermal phase curve of 55 Cancri e is the first measurement of the temperature distribution of a tidally locked super-Earth, but raises a number of puzzling questions about the planet's climate. The phase curve has a high amplitude and peak offset, suggesting that it has a significant eastward hot-spot shift as well as a large day-night temperature contrast. We use a general circulation model to model potential climates, and investigate the relation between bulk atmospheric composition and the magnitude of these seemingly contradictory features. We confirm theoretical models of tidally locked circulation are consistent with our numerical model of 55 Cnc e, and rule out certain atmospheric compositions based on their thermodynamic properties. Our best-fitting atmosphere has a significant hot-spot shift and day-night contrast, although these are not as large as the observed phase curve. We discuss possible physical processes that could explain the observations, and show that night-side cloud formation from species such as SiO from a day-side magma ocean could potentially increase the phase curve amplitude and explain the observations. We conclude that the observations could be explained by an optically thick atmosphere with a low mean molecular weight, a surface pressure of several bars, and a strong eastward circulation, with night-side cloud formation a possible explanation for the difference between our model and the observations. © 2017. The American Astronomical Society. All rights reserved."
"57196436816;23095483400;15840467900;57196441587;57196439738;35194679200;35772803100;57196442534;","Unveiling aerosol-cloud interactions - Part 1: Cloud contamination in satellite products enhances the aerosol indirect forcing estimate",2017,"10.5194/acp-17-13151-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033218029&doi=10.5194%2facp-17-13151-2017&partnerID=40&md5=46a4bbd8e6f89004f4fa00cc5846f3d5","Increased concentrations of aerosol can enhance the albedo of warm low-level cloud. Accurately quantifying this relationship from space is challenging due in part to contamination of aerosol statistics near clouds. Aerosol retrievals near clouds can be influenced by stray cloud particles in areas assumed to be cloud-free, particle swelling by humidification, shadows and enhanced scattering into the aerosol field from (3-D radiative transfer) clouds. To screen for this contamination we have developed a new cloud-aerosol pairing algorithm (CAPA) to link cloud observations to the nearest aerosol retrieval within the satellite image. The distance between each aerosol retrieval and nearest cloud is also computed in CAPA. <br></br> Results from two independent satellite imagers, the Advanced Along-Track Scanning Radiometer (AATSR) and Moderate Resolution Imaging Spectroradiometer (MODIS), show a marked reduction in the strength of the intrinsic aerosol indirect radiative forcing when selecting aerosol pairs that are located farther away from the clouds (ĝ'0.28±0.26ĝ€Wĝ€mĝ'2) compared to those including pairs that are within 15ĝ€km of the nearest cloud (ĝ'0.49±0.18ĝ€Wĝ€mĝ'2). The larger aerosol optical depths in closer proximity to cloud artificially enhance the relationship between aerosol-loading, cloud albedo, and cloud fraction. These results suggest that previous satellite-based radiative forcing estimates represented in key climate reports may be exaggerated due to the inclusion of retrieval artefacts in the aerosol located near clouds."
"23095483400;57196436816;15840467900;57203053317;","Unveiling aerosol-cloud interactions - Part 2: Minimising the effects of aerosol swelling and wet scavenging in ECHAM6-HAM2 for comparison to satellite data",2017,"10.5194/acp-17-13165-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033227771&doi=10.5194%2facp-17-13165-2017&partnerID=40&md5=dd65b35c08abc9b25604112b054c4042","Aerosol-cloud interactions (ACIs) are uncertain and the estimates of the ACI effective radiative forcing (ERFaci) magnitude show a large variability. Within the Aerosol-cci project the susceptibility of cloud properties to changes in aerosol properties is derived from the high-resolution AATSR (Advanced Along-Track Scanning Radiometer) data set using the Cloud-Aerosol Pairing Algorithm (CAPA) (as described in our companion paper) and compared to susceptibilities from the global aerosol climate model ECHAM6-HAM2 and MODIS-CERES (Moderate Resolution Imaging Spectroradiometer - Clouds and the Earth's Radiant Energy System) data. For ECHAM6-HAM2 the dry aerosol is analysed to mimic the effect of CAPA. Furthermore the analysis is done for different environmental regimes. <br></br> The aerosol-liquid water path relationship in ECHAM6-HAM2 is systematically stronger than in AATSR-CAPA data and cannot be explained by an overestimation of autoconversion when using diagnostic precipitation but rather by aerosol swelling in regions where humidity is high and clouds are present. When aerosol water is removed from the analysis in ECHAM6-HAM2 the strength of the susceptibilities of liquid water path, cloud droplet number concentration and cloud albedo as well as ERFaci agree much better with those of AATSR-CAPA or MODIS-CERES. When comparing satellite-derived to model-derived susceptibilities, this study finds it more appropriate to use dry aerosol in the computation of model susceptibilities. <br></br> We further find that the statistical relationships inferred from different satellite sensors (AATSR-CAPA vs. MODIS-CERES) as well as from ECHAM6-HAM2 are not always of the same sign for the tested environmental conditions. In particular the susceptibility of the liquid water path is negative in non-raining scenes for MODIS-CERES but positive for AATSR-CAPA and ECHAM6-HAM2. Feedback processes like cloud-top entrainment that are missing or not well represented in the model are therefore not well constrained by satellite observations. <br></br> In addition to aerosol swelling, wet scavenging and aerosol processing have an impact on liquid water path, cloud albedo and cloud droplet number susceptibilities. Aerosol processing leads to negative liquid water path susceptibilities to changes in aerosol index (AI) in ECHAM6-HAM2, likely due to aerosol-size changes by aerosol processing. <br></br> Our results indicate that for statistical analysis of aerosol-cloud interactions the unwanted effects of aerosol swelling, wet scavenging and aerosol processing need to be minimised when computing susceptibilities of cloud variables to changes in aerosol."
"55683113200;36194896400;8950640300;24722810700;57196450352;55351271700;56364931100;57196458990;57132504600;7005569573;35867336200;7202646749;6603458409;7006204597;16444265000;57203258129;57203231853;7004027519;","Frequent ultrafine particle formation and growth in Canadian Arctic marine and coastal environments",2017,"10.5194/acp-17-13119-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033375850&doi=10.5194%2facp-17-13119-2017&partnerID=40&md5=218217f6f87262d4e66ee93554b53d94","The source strength and capability of aerosol particles in the Arctic to act as cloud condensation nuclei have important implications for understanding the indirect aerosol-cloud effect within the polar climate system. It has been shown in several Arctic regions that ultrafine particle (UFP) formation and growth is a key contributor to aerosol number concentrations during the summer. This study uses aerosol number size distribution measurements from shipboard expeditions aboard the research icebreaker CCGS Amundsen in the summers of 2014 and 2016 throughout the Canadian Arctic to gain a deeper understanding of the drivers of UFP formation and growth within this marine boundary layer. UFP number concentrations (diameter 4nm) in the range of 101-104cm-3 were observed during the two seasons, with concentrations greater than 103cm-3 occurring more frequently in 2016. Higher concentrations in 2016 were associated with UFP formation and growth, with events occurring on 41% of days, while events were only observed on 6% of days in 2014. Assessment of relevant parameters for aerosol nucleation showed that the median condensation sink in this region was approximately 1.2h-1 in 2016 and 2.2h-1 in 2014, which lie at the lower end of ranges observed at even the most remote stations reported in the literature. Apparent growth rates of all observed events in both expeditions averaged 4.3±4.1nmh-1, in general agreement with other recent studies at similar latitudes. Higher solar radiation, lower cloud fractions, and lower sea ice concentrations combined with differences in the developmental stage and activity of marine microbial communities within the Canadian Arctic were documented and help explain differences between the aerosol measurements made during the 2014 and 2016 expeditions. These findings help to motivate further studies of biosphere-atmosphere interactions within the Arctic marine environment to explain the production of UFP and their growth to sizes relevant for cloud droplet activation."
"26638618800;7407104838;57196439405;53878006900;35096299800;7005955015;","Marine cloud brightening - As effective without clouds",2017,"10.5194/acp-17-13071-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033236389&doi=10.5194%2facp-17-13071-2017&partnerID=40&md5=ad8bfec0a059ea5d9f5930b3893d1b5e","Marine cloud brightening through sea spray injection has been proposed as a climate engineering method for avoiding the most severe consequences of global warming. A limitation of most of the previous modelling studies on marine cloud brightening is that they have either considered individual models or only investigated the effects of a specific increase in the number of cloud droplets. Here we present results from coordinated simulations with three Earth system models (ESMs) participating in the Geoengineering Model Intercomparison Project (GeoMIP) G4sea-salt experiment. Injection rates of accumulation-mode sea spray aerosol particles over ocean between 30°ĝ€N and 30°ĝ€S are set in each model to generate a global-mean effective radiative forcing (ERF) of ĝ'2.0ĝ€Wĝ€†mĝ'2 at the top of the atmosphere. We find that the injection increases the cloud droplet number concentration in lower layers, reduces the cloud-top effective droplet radius, and increases the cloud optical depth over the injection area. We also find, however, that the global-mean clear-sky ERF by the injected particles is as large as the corresponding total ERF in all three ESMs, indicating a large potential of the aerosol direct effect in regions of low cloudiness. The largest enhancement in ERF due to the presence of clouds occur as expected in the subtropical stratocumulus regions off the west coasts of the American and African continents. However, outside these regions, the ERF is in general equally large in cloudy and clear-sky conditions. These findings suggest a more important role of the aerosol direct effect in sea spray climate engineering than previously thought."
"57196437027;57196441294;7201787800;7006377579;57195257572;21933618400;37089603000;22834248200;8581789300;55581504800;55581504800;57196442038;6701802669;","In situ measurements of cloud microphysics and aerosol over coastal Antarctica during the MAC campaign",2017,"10.5194/acp-17-13049-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028723346&doi=10.5194%2facp-17-13049-2017&partnerID=40&md5=2eab27fffcc917855f5a36ea7bd70e22","During austral summer 2015, the Microphysics of Antarctic Clouds (MAC) field campaign collected unique and detailed airborne and ground-based in situ measurements of cloud and aerosol properties over coastal Antarctica and the Weddell Sea. This paper presents the first results from the experiment and discusses the key processes important in this region, which is critical to predicting future climate change. <br><br> The sampling was predominantly of stratus clouds, at temperatures between ĝ'20 and 0ĝ€°C. These clouds were dominated by supercooled liquid water droplets, which had a median concentration of 113ĝ€cmĝ'3 and an interquartile range of 86ĝ€cmĝ'3. Both cloud liquid water content and effective radius increased closer to cloud top. The cloud droplet effective radius increased from 4ĝ€±ĝ€2ĝ€μm near cloud base to 8ĝ€±ĝ€3ĝ€μm near cloud top. <br><br> Cloud ice particle concentrations were highly variable with the ice tending to occur in small, isolated patches. Below approximately 1000ĝ€m, glaciated cloud regions were more common at higher temperatures; however, the clouds were still predominantly liquid throughout. When ice was present at temperatures higher than ĝ'10ĝ€°C, secondary ice production most likely through the Hallett&ndash;Mossop mechanism led to ice concentrations 1 to 3 orders of magnitude higher than the number predicted by commonly used primary ice nucleation parameterisations. The drivers of the ice crystal variability are investigated. No clear dependence on the droplet size distribution was found. The source of first ice in the clouds remains uncertain but may include contributions from biogenic particles, blowing snow or other surface ice production mechanisms. <br><br> The concentration of large aerosols (diameters 0.5 to 1.6ĝ€μm) decreased with altitude and were depleted in air masses that originated over the Antarctic continent compared to those more heavily influenced by the Southern Ocean and sea ice regions. The dominant aerosol in the region was hygroscopic in nature, with the hygroscopicity parameter <i>°</i> having a median value for the campaign of 0.66 (interquartile range of 0.38). This is consistent with other remote marine locations that are dominated by sea salt/sulfate."
"56458676300;56058445700;6506270236;7007162501;7006821210;22939204200;","Characterization of free amino acids, bacteria and fungi in size-segregated atmospheric aerosols in boreal forest: Seasonal patterns, abundances and size distributions",2017,"10.5194/acp-17-13089-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033237318&doi=10.5194%2facp-17-13089-2017&partnerID=40&md5=2f475e43881b0fae01d557b039b00e3c","Primary biological aerosol particles (PBAPs) are ubiquitous in the atmosphere and constitute ĝ1/4&thinsp;30ĝ€% of atmospheric aerosol particle mass in sizesĝ€ &gt;&thinsp;1ĝ€μm. PBAP components, such as bacteria, fungi and pollen, may affect the climate by acting as cloud-active particles, thus having an effect on cloud and precipitation formation processes. In this study, size-segregated aerosol samples (&lt;&thinsp;1.0, 1&ndash;2.5, 2.5&ndash;10 and &gt;&thinsp;10ĝ€μm) were collected in boreal forest (Hyytiälä, Finland) during a 9-month period covering all seasons and analysed for free amino acids (FAAs), DNA concentration and microorganism (bacteria, <i>Pseudomonas</i> and fungi). Measurements were performed using tandem mass spectrometry, spectrophotometry and qPCR, respectively. Meteorological parameters and statistical analysis were used to study their atmospheric implication for results. Distinct annual patterns of PBAP components were observed, late spring and autumn being seasons of dominant occurrence. Elevated abundances of FAAs and bacteria were observed during the local pollen season, whereas fungi were observed at the highest level during autumn. Meteorological parameters such as air and soil temperature, radiation and rainfall were observed to possess a close relationship with PBAP abundances on an annual scale."
"7202158002;24759983400;10239531200;","Searching for the 27-day solar rotational cycle in lightning events recorded in old diaries in Kyoto from the 17th to 18th century",2017,"10.5194/angeo-35-1195-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033498698&doi=10.5194%2fangeo-35-1195-2017&partnerID=40&md5=9033a7d3a6c7a346a357f4323012642d","A solar rotational period of approximately 27 days has been detected in cloud and lightning activities, although the mechanism of the sun-climate connection remains unclear. In previous studies, lightning activity in Japan showed a significant signal of the solar rotational period, especially around the maxima of the decadal solar cycles. Here we analyze the time series of lightning activity in the AD 1668-1767 period, extracted from old diaries in Kyoto, Japan, and search for the signal of solar rotational cycles. The 27-day cycles were detected in the lightning data and occurred only around the maxima of the decadal sunspot cycles. The signal disappeared during AD 1668-1715, which corresponds to the latter half of the Maunder Minimum when both radiative and magnetic disturbances were thought to have been weak. These findings provide insight into the connection between solar activity and the Earth's climate. © Author(s) 2017."
"56165543200;7005209721;","Monitoring tropical debris-covered glacier dynamics from high-resolution unmanned aerial vehicle photogrammetry, Cordillera Blanca, Peru",2017,"10.5194/tc-11-2463-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021115181&doi=10.5194%2ftc-11-2463-2017&partnerID=40&md5=882330abecfd79c672812e1bddee5386","The glaciers of the Cordillera Blanca, Peru, are rapidly retreating and thinning as a result of climate change, altering the timing, quantity and quality of water available to downstream users. Furthermore, increases in the number and size of proglacial lakes associated with these melting glaciers is increasing potential exposure to glacier lake outburst floods (GLOFs). Understanding how these glaciers are changing and their connection to proglacial lake systems is thus of critical importance. Most satellite data are too coarse for studying small mountain glaciers and are often affected by cloud cover, while traditional airborne photogrammetry and lidar are costly. Recent developments have made unmanned aerial vehicles (UAVs) a viable and potentially transformative method for studying glacier change at high spatial resolution, on demand and at relatively low cost. Using a custom designed hexacopter built for high-altitude (4000-6000ma.s.l.) operation, we completed repeat aerial surveys (2014 and 2015) of the debris-covered Llaca Glacier tongue and proglacial lake system. High-resolution orthomosaics (5 cm) and digital elevation models (DEMs) (10 cm) were produced and their accuracy assessed. Analysis of these datasets reveals highly heterogeneous patterns of glacier change. The most rapid areas of ice loss were associated with exposed ice cliffs and meltwater ponds on the glacier surface. Considerable subsidence and low surface velocities were also measured on the sediments within the pro-glacial lake, indicating the presence of extensive regions of buried ice and continued connection to the glacier tongue. Only limited horizontal retreat of the glacier tongue was observed, indicating that measurements of changes in aerial extent alone are inadequate for monitoring changes in glacier ice quantity. © 2017 Author(s)."
"55798291900;57213411726;7006272211;24773185500;","Impact of biofuels on contrail warming",2017,"10.1088/1748-9326/aa893b","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85036631411&doi=10.1088%2f1748-9326%2faa893b&partnerID=40&md5=219ec33390bac4a260cb5f6636c39437","Contrails and contrail-cirrus may be the largest source of radiative forcing (RF) attributable to aviation. Biomass-derived alternative jet fuels are a potentially major way to mitigate the climate impacts of aviation by reducing lifecycle CO2 emissions. Given the up to 90% reduction in soot emissions from paraffinic biofuels, the potential for a significant impact on contrail RF due to the reduction in contrail-forming ice nuclei (IN) remains an open question. We simulate contrail formation and evolution to quantify RF over the United States under different emissions scenarios. Replacing conventional jet fuels with paraffinic biofuels generates two competing effects. First, the higher water emissions index results in an increase in contrail occurrence (∼ +8%). On the other hand, these contrails are composed of larger diameter crystals (∼ +58%) at lower number concentrations (∼ -75%), reducing both contrail optical depth (∼ -29%) and albedo (∼ -32%). The net changes in contrail RF induced by switching to biofuels range from -4% to +18% among a range of assumed ice crystal habits (shapes). In comparison, cleaner burning engines (with no increase in water emissions index) result in changes to net contrail RF ranging between -13% and +5% depending on habit. Thus, we find that even 67% to 75% reductions in aircraft soot emissions are insufficient to substantially reduce warming from contrails, and that the use of biofuels may either increase or decrease contrail warming - contrary to previous expectations of a significant decrease in warming. © 2017 The Author(s). Published by IOP Publishing Ltd."
"7003865921;6603925960;57207507108;57189386544;","Observational Constraints on Cloud Feedbacks: The Role of Active Satellite Sensors",2017,"10.1007/s10712-017-9452-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85035801783&doi=10.1007%2fs10712-017-9452-0&partnerID=40&md5=457c3231781fe4e5d43de3f27878b6f3","Cloud profiling from active lidar and radar in the A-train satellite constellation has significantly advanced our understanding of clouds and their role in the climate system. Nevertheless, the response of clouds to a warming climate remains one of the largest uncertainties in predicting climate change and for the development of adaptions to change. Both observation of long-term changes and observational constraints on the processes responsible for those changes are necessary. We review recent progress in our understanding of the cloud feedback problem. Capabilities and advantages of active sensors for observing clouds are discussed, along with the importance of active sensors for deriving constraints on cloud feedbacks as an essential component of a global climate observing system. © 2017, The Author(s)."
"7402064802;7403288995;7401776640;57205867148;","Low-Cloud Feedbacks from Cloud-Controlling Factors: A Review",2017,"10.1007/s10712-017-9433-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032001092&doi=10.1007%2fs10712-017-9433-3&partnerID=40&md5=97e92667b5624d0cff6e37de2b38bf18","The response to warming of tropical low-level clouds including both marine stratocumulus and trade cumulus is a major source of uncertainty in projections of future climate. Climate model simulations of the response vary widely, reflecting the difficulty the models have in simulating these clouds. These inadequacies have led to alternative approaches to predict low-cloud feedbacks. Here, we review an observational approach that relies on the assumption that observed relationships between low clouds and the “cloud-controlling factors” of the large-scale environment are invariant across time-scales. With this assumption, and given predictions of how the cloud-controlling factors change with climate warming, one can predict low-cloud feedbacks without using any model simulation of low clouds. We discuss both fundamental and implementation issues with this approach and suggest steps that could reduce uncertainty in the predicted low-cloud feedback. Recent studies using this approach predict that the tropical low-cloud feedback is positive mainly due to the observation that reflection of solar radiation by low clouds decreases as temperature increases, holding all other cloud-controlling factors fixed. The positive feedback from temperature is partially offset by a negative feedback from the tendency for the inversion strength to increase in a warming world, with other cloud-controlling factors playing a smaller role. A consensus estimate from these studies for the contribution of tropical low clouds to the global mean cloud feedback is 0.25 ± 0.18 W m−2 K−1 (90% confidence interval), suggesting it is very unlikely that tropical low clouds reduce total global cloud feedback. Because the prediction of positive tropical low-cloud feedback with this approach is consistent with independent evidence from low-cloud feedback studies using high-resolution cloud models, progress is being made in reducing this key climate uncertainty. © 2017, The Author(s)."
"35509639400;7201504886;16444240700;24723648200;56212055700;6603868770;23017945100;7006184606;55883785100;35551238800;22133985200;57206156792;6603418610;57202531041;23492864500;55940978200;23768540500;6603566335;6602115663;56198145500;35621058500;56567409000;57190209035;7201423091;","EUREC4A: A Field Campaign to Elucidate the Couplings Between Clouds, Convection and Circulation",2017,"10.1007/s10712-017-9428-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030099198&doi=10.1007%2fs10712-017-9428-0&partnerID=40&md5=df9180e49db240179718c7784676b9d6","Trade-wind cumuli constitute the cloud type with the highest frequency of occurrence on Earth, and it has been shown that their sensitivity to changing environmental conditions will critically influence the magnitude and pace of future global warming. Research over the last decade has pointed out the importance of the interplay between clouds, convection and circulation in controling this sensitivity. Numerical models represent this interplay in diverse ways, which translates into different responses of trade-cumuli to climate perturbations. Climate models predict that the area covered by shallow cumuli at cloud base is very sensitive to changes in environmental conditions, while process models suggest the opposite. To understand and resolve this contradiction, we propose to organize a field campaign aimed at quantifying the physical properties of trade-cumuli (e.g., cloud fraction and water content) as a function of the large-scale environment. Beyond a better understanding of clouds-circulation coupling processes, the campaign will provide a reference data set that may be used as a benchmark for advancing the modelling and the satellite remote sensing of clouds and circulation. It will also be an opportunity for complementary investigations such as evaluating model convective parameterizations or studying the role of ocean mesoscale eddies in air–sea interactions and convective organization. © 2017, The Author(s)."
"54897465300;7103294731;","Contributions of climate feedbacks to changes in atmospheric circulation",2017,"10.1175/JCLI-D-17-0189.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032286018&doi=10.1175%2fJCLI-D-17-0189.1&partnerID=40&md5=1a48466624b6308423edc2b3c58878f6","The projected response of the atmospheric circulation to the radiative changes induced by CO2 forcing and climate feedbacks is currently uncertain. In this modeling study, the impact of CO2-induced climate feedbacks on changes in jet latitude and speed is assessed by imposing surface albedo, cloud, and water vapor feedbacks as if they were forcings in two climate models, CAM4 and ECHAM6. The jet response to radiative feedbacks can be broadly interpreted through changes in midlatitude baroclinicity. Clouds enhance baroclinicity, favoring a strengthened, poleward-shifted jet; this is mitigated by surface albedo changes, which have the opposite effect on baroclinicity and the jet, while water vapor has opposing effects on upper- and lower-level baroclinicity with little net impact on the jet. Large differences between the CAM4 and ECHAM6 responses illustrate how model uncertainty in radiative feedbacks causes a large spread in the baroclinicity response to CO2 forcing. Across the CMIP5 models, differences in shortwave feedbacks by clouds and albedo are a dominant contribution to this spread. Forcing CAM4 with shortwave cloud and albedo feedbacks from a representative set of CMIP5 models yields a wide range of jet responses that strongly correlate with the meridional gradient of the anomalous shortwave heating and the associated baroclinicity response. Differences in shortwave feedbacks statistically explain about 50% of the intermodel spread in CMIP5 jet shifts for the set of models used, demonstrating the importance of constraining radiative feedbacks for accurate projections of circulation changes. © 2017 American Meteorological Society."
"7006544303;57195445069;55443788900;55694342800;6507237454;55570003600;7005246733;","Climate engine: Cloud computing and visualization of climate and remote sensing data for advanced natural resource monitoring and process understanding",2017,"10.1175/BAMS-D-15-00324.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85036635164&doi=10.1175%2fBAMS-D-15-00324.1&partnerID=40&md5=98c3e615634f5d9cf32b4cafcac139fb","Climate Engine enables users to process, visualize, download, and share climate and remote sensing datasets with a simple web connection, thereby overcoming common big data barriers. © 2017 American Meteorological Society."
"7003543851;7202733689;","The large-scale dynamical response of clouds to aerosol forcing",2017,"10.1175/JCLI-D-17-0050.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032212095&doi=10.1175%2fJCLI-D-17-0050.1&partnerID=40&md5=80f51497ff6933d85dbea9196c2bac47","Radiative kernels are used to quantify the instantaneous radiative forcing of aerosols and the aerosol-mediated cloud response in coupled ocean-atmosphere model simulations under both historical and future emission scenarios. The method is evaluated using matching pairs of historical climate change experiments with and without aerosol forcing and accurately captures the spatial pattern and global-mean effects of aerosol forcing. It is shown that aerosol-driven changes in the atmospheric circulation induce additional cloud changes. Thus, the total aerosol-mediated cloud response consists of both local microphysical changes and nonlocal dynamical changes that are driven by hemispheric asymmetries in aerosol forcing. By comparing coupled and fixed sea surface temperature (SST) simulations with identical aerosol forcing, the relative contributions of these two components are isolated, exploiting the ability of prescribed SSTs to also suppress changes in the atmospheric circulation. The radiative impact of the dynamical cloud changes is found to be comparable in magnitude to that of the microphysical cloud changes and acts to further amplify the interhemispheric asymmetry of the aerosol radiative forcing. The dynamical cloud response is closely linked to the meridional displacement of the Hadley cell, which, in turn, is driven by changes in the cross-equatorial energy transport. In this way, the dynamical cloud changes act as a positive feedback on the meridional displacement of the Hadley cell, roughly doubling the projected changes in cross-equatorial energy transport compared to that from the microphysical changes alone. © 2017 American Meteorological Society."
"55910831200;6507400558;7006698304;","Coastal Tropical Convection in a Stochastic Modeling Framework",2017,"10.1002/2017MS001048","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034102381&doi=10.1002%2f2017MS001048&partnerID=40&md5=5e004224a9e28ef7828db9a999211b85","Recent research has suggested that the overall dependence of convection near coasts on large-scale atmospheric conditions is weaker than over the open ocean or inland areas. This is due to the fact that in coastal regions convection is often supported by meso-scale land-sea interactions and the topography of coastal areas. As these effects are not resolved and not included in standard cumulus parametrization schemes, coastal convection is among the most poorly simulated phenomena in global models. To outline a possible parametrization framework for coastal convection we develop an idealized modeling approach and test its ability to capture the main characteristics of coastal convection. The new approach first develops a decision algorithm, or trigger function, for the existence of coastal convection. The function is then applied in a stochastic cloud model to increase the occurrence probability of deep convection when land-sea interactions are diagnosed to be important. The results suggest that the combination of the trigger function with a stochastic model is able to capture the occurrence of deep convection in atmospheric conditions often found for coastal convection. When coastal effects are deemed to be present the spatial and temporal organization of clouds that has been documented form observations is well captured by the model. The presented modeling approach has therefore potential to improve the representation of clouds and convection in global numerical weather forecasting and climate models. © 2017. The Authors."
"57195775669;9233708300;24778157400;9846673800;","Exploring noctilucent cloud variability using the nudged and extended version of the Canadian Middle Atmosphere Model",2017,"10.1016/j.jastp.2017.08.019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029819299&doi=10.1016%2fj.jastp.2017.08.019&partnerID=40&md5=89473d75cddea680db2cc16ad77f757b","Ice particles in the summer mesosphere – such as those connected to noctilucent clouds and polar mesospheric summer echoes - have since their discovery contributed to the uncovering of atmospheric processes on various scales ranging from interactions on molecular levels to global scale circulation patterns. While there are numerous model studies on mesospheric ice microphysics and how the clouds relate to the background atmosphere, there are at this point few studies using comprehensive global climate models to investigate observed variability and climatology of noctilucent clouds. In this study it is explored to what extent the large-scale inter-annual characteristics of noctilucent clouds are captured in a 30-year run - extending from 1979 to 2009 - of the nudged and extended version of the Canadian Middle Atmosphere Model (CMAM30). To construct and investigate zonal mean inter-seasonal variability in noctilucent cloud occurrence frequency and ice mass density in both hemispheres, a simple cloud model is applied in which it is assumed that the ice content is solely controlled by the local temperature and water vapor volume mixing ratio. The model results are compared to satellite observations, each having an instrument-specific sensitivity when it comes to detecting noctilucent clouds. It is found that the model is able to capture the onset dates of the NLC seasons in both hemispheres as well as the hemispheric differences in NLCs, such as weaker NLCs in the SH than in the NH and differences in cloud height. We conclude that the observed cloud climatology and zonal mean variability are well captured by the model. © 2017 The Authors"
"7402677913;7004862277;7005729142;7103271625;","Modeling of aircraft measurements of ice crystal concentration in the Arctic and a parameterization for mixed-phase cloud",2017,"10.1175/JAS-D-17-0037.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034785587&doi=10.1175%2fJAS-D-17-0037.1&partnerID=40&md5=48e947bd5d0d23569e3054731a92de7b","In this study, two parameterizations of ice nucleation rate on dust particles are used in a parcel model to simulate aircraft measurements of ice crystal number concentration Ni in the Arctic. The parcel model has detailed microphysics for droplet and ice nucleation, growth, and evaporation with prescribed vertical air velocities. Three dynamic regimes are considered, including large-scale ascent, cloud-top generating cells, and their combination. With observed meteorological conditions and aerosol concentrations, the parcel model predicts the number concentrations of size-resolved ice crystals, which may be compared to aircraft measurements. Model results show rapid changes with height/time in relative humidity, Ni, and thermodynamic phase partitioning, which is not resolved in current climate and weather forecasting models. Parameterizations for ice number and nucleation rate in mixed-phase stratus clouds are thus developed based on the parcel model results to represent the time-integrated effect of some microphysical processes in large-scale models. © 2017 American Meteorological Society."
"15765851100;6701518904;12645767500;6701820543;7003696273;6603196991;55754577000;7005457526;56771426500;7003865921;","Emerging Technologies and Synergies for Airborne and Space-Based Measurements of Water Vapor Profiles",2017,"10.1007/s10712-017-9448-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034663094&doi=10.1007%2fs10712-017-9448-9&partnerID=40&md5=f78b812f63978398b3bf12e797e926e3","A deeper understanding of how clouds will respond to a warming climate is one of the outstanding challenges in climate science. Uncertainties in the response of clouds, and particularly shallow clouds, have been identified as the dominant source of the discrepancy in model estimates of equilibrium climate sensitivity. As the community gains a deeper understanding of the many processes involved, there is a growing appreciation of the critical role played by fluctuations in water vapor and the coupling of water vapor and atmospheric circulations. Reduction of uncertainties in cloud-climate feedbacks and convection initiation as well as improved understanding of processes governing these effects will result from profiling of water vapor in the lower troposphere with improved accuracy and vertical resolution compared to existing airborne and space-based measurements. This paper highlights new technologies and improved measurement approaches for measuring lower tropospheric water vapor and their expected added value to current observations. Those include differential absorption lidar and radar, microwave occultation between low-Earth orbiters, and hyperspectral microwave remote sensing. Each methodology is briefly explained, and measurement capabilities as well as the current technological readiness for aircraft and satellite implementation are specified. Potential synergies between the technologies are discussed, actual examples hereof are given, and future perspectives are explored. Based on technical maturity and the foreseen near-mid-term development path of the various discussed measurement approaches, we find that improved measurements of water vapor throughout the troposphere would greatly benefit from the combination of differential absorption lidar focusing on the lower troposphere with passive remote sensors constraining the upper-tropospheric humidity. © 2017, The Author(s)."
"56543976600;6701709684;","Using polarimetry to retrieve the cloud coverage of Earth-like exoplanets",2017,"10.1051/0004-6361/201730586","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034108152&doi=10.1051%2f0004-6361%2f201730586&partnerID=40&md5=57df5adf8b06af5e0434f80ef05e33df","Context. Clouds have already been detected in exoplanetary atmospheres. They play crucial roles in a planet's atmosphere and climate and can also create ambiguities in the determination of atmospheric parameters such as trace gas mixing ratios. Knowledge of cloud properties is required when assessing the habitability of a planet. Aims. We aim to show that various types of cloud cover such as polar cusps, subsolar clouds, and patchy clouds on Earth-like exoplanets can be distinguished from each other using the polarization and flux of light that is reflected by the planet. Methods. We have computed the flux and polarization of reflected starlight for different types of (liquid water) cloud covers on Earth-like model planets using the adding-doubling method, that fully includes multiple scattering and polarization. Variations in cloud-top altitudes and planet-wide cloud cover percentages were taken into account. Results. We find that the different types of cloud cover (polar cusps, subsolar clouds, and patchy clouds) can be distinguished from each other and that the percentage of cloud cover can be estimated within 10%. Conclusions. Using our proposed observational strategy, one should be able to determine basic orbital parameters of a planet such as orbital inclination and estimate cloud coverage with reduced ambiguities from the planet's polarization signals along its orbit. © ESO, 2017."
"55184057600;8511991900;34772240500;55738957800;7003666669;7403282069;15755995900;8922308700;","Assessing the Resolution Adaptability of the Zhang-McFarlane Cumulus Parameterization With Spatial and Temporal Averaging",2017,"10.1002/2017MS001035","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85036584483&doi=10.1002%2f2017MS001035&partnerID=40&md5=06a65a04b81b1e5c670565fafdccdd10","With increasing computational capabilities, cumulus parameterizations that are adaptable to the smaller grid spacing and temporal interval for high-resolution climate model simulations are needed. In this study, we propose a method to improve the resolution adaptability of the Zhang-McFarlane (ZM) scheme, by implementing spatial and temporal averaging to the CAPE tendency. This method allows for a more consistent application of the quasi-equilibrium (QE) hypothesis at high spatial and temporal resolutions. The resolution adaptability of the original ZM scheme, the scheme with spatial averaging, and the scheme with spatiotemporal averaging at 4–32 km grid spacings are assessed using the Weather Research and Forecasting (WRF) model by comparing to cloud resolving model (CRM) simulation results coarse-grained to these same grid spacings. We show the original ZM scheme has poor resolution adaptability, with spatiotemporally averaged subgrid convective transport and convective precipitation increasing significantly as the resolution increases. The spatial averaging method improves the resolution adaptability of the ZM scheme and better conserves total transport and total precipitation. Temporal averaging further improves the resolution adaptability of the scheme. With better constrained (although smoothed) convective transport and precipitation, both the spatial distribution and time series of total precipitation at 4 and 8 km grid spacings are improved with the averaging methods. The results could help develop resolution adaptability for other cumulus parameterizations that are based on the QE assumption. © 2017. The Authors."
"56471429200;55437450100;","Double and single ITCZs with and without clouds",2017,"10.1175/JCLI-D-17-0062.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031683712&doi=10.1175%2fJCLI-D-17-0062.1&partnerID=40&md5=b14c11d156431ef7a64ee73cde2153c8","A major bias in tropical precipitation over the Pacific in climate simulations stems from the models' tendency to produce two strong distinct intertropical convergence zones (ITCZs) too often. Several mechanisms have been proposed that may contribute to the emergence of two ITCZs, but current theories cannot fully explain the bias. This problem is tackled by investigating how the interaction between atmospheric cloud-radiative effects (ACREs) and the large-scale circulation influences the ITCZ position in an atmospheric general circulation model. Simulations are performed in an idealized aquaplanet setup and the longwave and shortwave ACREs are turned off individually or jointly. The low-level moist static energy (MSE) is shown to be a good predictor of the ITCZ position. Therefore, a mechanism is proposed that explains the changes in MSE and thus ITCZ position due to ACREs consistently across simulations. The mechanism implies that the ITCZ moves equatorward if the Hadley circulation strengthens because of the increased upgradient advection of low-level MSE off the equator. The longwave ACRE increases the meridional heating gradient in the tropics and as a response the Hadley circulation strengthens and the ITCZ moves equatorward. The shortwave ACRE has the opposite effect. The total ACRE pulls the ITCZ equatorward. This mechanism is discussed in other frameworks involving convective available potential energy, gross moist stability, and the energy flux equator. It is thus shown that the response of the large-scale circulation to the shortwave and longwave ACREs is a fundamental driver of changes in the ITCZ position. © 2017 American Meteorological Society."
"7410069943;7501757094;7401796996;7402727736;","Cloud-radiation-precipitation associations over the Asian monsoon region: an observational analysis",2017,"10.1007/s00382-016-3509-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010821980&doi=10.1007%2fs00382-016-3509-5&partnerID=40&md5=5caa8f4f5b5cdf0ff1b2b3445af3fb78","This study uses 2001–2014 satellite observations and reanalyses to investigate the seasonal characteristics of Cloud Radiative Effects (CREs) and their associations with cloud fraction (CF) and precipitation over the Asian monsoon region (AMR) covering Eastern China (EC) and South Asia (SA). The CREs exhibit strong seasonal variations but show distinctly different relationships with CFs and precipitation over the two regions. For EC, the CREs is dominated by shortwave (SW) cooling, with an annual mean value of − 40 W m− 2 for net CRE, and peak in summer while the presence of extensive and opaque low-level clouds contributes to large Top-Of-Atmosphere (TOA) albedo (&gt;0.5) in winter. For SA, a weak net CRE exists throughout the year due to in-phase compensation of SWCRE by longwave (LW) CRE associated with the frequent occurrence of high clouds. For the entire AMR, SWCRE strongly correlates with the dominant types of CFs, although the cloud vertical structure plays important role particularly in summer. The relationships between CREs and precipitation are stronger in SA than in EC, indicating the dominant effect of monsoon circulation in the former region. SWCRE over EC is only partly related to precipitation and shows distinctive regional variations. Further studies need to pay more attention to vertical distributions of cloud micro- and macro-physical properties, and associated precipitation systems over the AMR. © 2017, Springer-Verlag Berlin Heidelberg."
"55159691900;","Optical characteristics of irregular atmospheric ice columns",2017,"10.1134/S1024856017060100","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85036642426&doi=10.1134%2fS1024856017060100&partnerID=40&md5=012277642c14520a93810145056af255","The study of cirrus clouds, which significantly affect the climate, is carried out using lidars. Interpretation of the lidar data is based on the direct solution of the problem of light scattering by particles of crystal clouds. Optical characteristics of perfect ice hexagonal columns, obtained previously, poorly agree with the lidar observation results. The work describes calculations of the optical characteristics of irregular hexagonal ice columns, which are in a good agreement with the experimental results. The calculations for particles with deformation of a dihedral angle of 90° are presented. It is shown that the logarithm of the scattering matrix can be linearly approximated well by the logarithm of the particle size. This can significantly accelerate the calculations of the optical characteristics of clouds. It is ascertained that the optical characteristics are in a good agreement with the lidar observation results throughout the range of sizes calculated even at deformation angles of a few degrees. © 2017, Pleiades Publishing, Ltd."
"6701518904;22133985200;7201423091;6506606807;","Airborne Lidar Observations of Water Vapor Variability in Tropical Shallow Convective Environment",2017,"10.1007/s10712-017-9431-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030559884&doi=10.1007%2fs10712-017-9431-5&partnerID=40&md5=ab7185543e0a95155c7c0d9392e31fc3","An airborne downward-pointing water vapor lidar provides two-dimensional, simultaneous curtains of atmospheric backscatter and humidity along the flight track with high accuracy and spatial resolution. In order to improve the knowledge on the coupling between clouds, circulation and climate in the trade wind region, the DLR (Deutsches Zentrum für Luft- und Raumfahrt) water vapor lidar was operated on board the German research aircraft HALO during the NARVAL (Next Generation Aircraft Remote Sensing for Validation Studies) field experiment in December 2013. Out of the wealth of about 30 flight hours or 25,000 km of data over the Tropical Atlantic Ocean east of Barbados, three ~ 2-h-long, representative segments from different flights were selected. Analyses of Meteosat Second Generation images and dropsondes complement this case study. All observations indicate a high heterogeneity of the humidity in the lowest 4 km of the tropical troposphere, as well as of the depth of the cloud (1–2 km thick) and sub-cloud layer (~ 1 km thick). At the winter trade inversion with its strong humidity jump of up to 9 g/kg in water vapor mixing ratio, the mixing ratio variance can attain 9 (g/kg)2, while below it typically ranges between 1 and 3 (g/kg)2. Layer depths and partial water vapor columns within the layers vary by up to a factor of 2. This affects the total tropospheric water vapor column, amounting on average to 28 kg/m2, by up to 10 kg/m2 or 36%. The dominant scale of the variability is given by the extent of regions with higher-than-average humidity and lies between 300 and 600 km. The variability mainly stems from the alternation between dry regions and moisture lifted by convection. Occasionally, up to 100-km large dry regions are observed. In between, convection pushes the trade inversion upward, sharpening the vertical moisture gradient that is colocated with the trade inversion. In most of the water vapor profiles, this gradient is stronger than the one located at the top of the sub-cloud layer. Lidar observations in concert with models accurately reproducing the observed variability are expected to help evaluate the role these findings play for climate. © 2017, Springer Science+Business Media B.V."
"55240576300;56183412100;57125072600;56767397900;57216494536;57194609307;","Moisture-induced greening of the South Asia over the past three decades",2017,"10.1111/gcb.13762","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021247786&doi=10.1111%2fgcb.13762&partnerID=40&md5=767bbee507c857e237abfadb2c420767","South Asia experienced a weakening of summer monsoon circulation in the past several decades, resulting in rainfall decline in wet regions. In comparison with other tropical ecosystems, quantitative assessments of the extent and triggers of vegetation change are lacking in assessing climate-change impacts over South Asia dominated by crops. Here, we use satellite-based Normalized Difference Vegetation Index (NDVI) to quantify spatial–temporal changes in vegetation greenness, and find a widespread annual greening trend that stands in contrast to the weakening of summer monsoon circulation particularly over the last decade. We further show that moisture supply is the primary factor limiting vegetation activity during dry season or in dry region, and cloud cover or temperature would become increasingly important in wet region. Enhanced moisture conditions over dry region, coinciding with the decline in monsoon, are mainly responsible for the widespread greening trend. This result thereby cautions the use of a unified monsoon index to predict South Asia's vegetation dynamics. Current climate–carbon models in general correctly reproduce the dominant control of moisture in the temporal characteristics of vegetation productivity. But the model ensemble cannot exactly reproduce the spatial pattern of satellite-based vegetation change mainly because of biases in climate simulations. The moisture-induced greening over South Asia, which is likely to persist into the wetter future, has significant implications for regional carbon cycling and maintaining food security. © 2017 John Wiley & Sons Ltd"
"7102284923;26656246100;8315173400;36772864900;7004326742;56695227400;","A State-Dependent Quantification of Climate Sensitivity Based on Paleodata of the Last 2.1 Million Years",2017,"10.1002/2017PA003190","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032951361&doi=10.1002%2f2017PA003190&partnerID=40&md5=e7a19592adecfc5b873aa4f413f337cc","The evidence from both data and models indicates that specific equilibrium climate sensitivity S[X]—the global annual mean surface temperature change (ΔTg) as a response to a change in radiative forcing X (ΔR[X])—is state dependent. Such a state dependency implies that the best fit in the scatterplot of ΔTg versus ΔR[X] is not a linear regression but can be some nonlinear or even nonsmooth function. While for the conventional linear case the slope (gradient) of the regression is correctly interpreted as the specific equilibrium climate sensitivity S[X], the interpretation is not straightforward in the nonlinear case. We here explain how such a state-dependent scatterplot needs to be interpreted and provide a theoretical understanding—or generalization—how to quantify S[X] in the nonlinear case. Finally, from data covering the last 2.1 Myr we show that—due to state dependency—the specific equilibrium climate sensitivity which considers radiative forcing of CO2 and land ice sheet (LI) albedo, S[co2,LI], is larger during interglacial states than during glacial conditions by more than a factor 2. ©2017. The Authors."
"57207570990;6701735773;23981063100;7004452524;8349315600;7004854393;6602743662;","The Surface Energy Budget Computed at the Grid-Scale of a Climate Model Challenged by Station Data in West Africa",2017,"10.1002/2017MS001081","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034806908&doi=10.1002%2f2017MS001081&partnerID=40&md5=b8453db9405c6b72b4cfd685a5ca83be","In most state-of-the-art climate models, systematic errors persist in the representation of the rainfall seasonality, near surface air temperature, and surface energy budget over West Africa, even during the dry season. Most biases are related to an incorrect latitudinal position of the monsoon structures. To disentangle the role of the large-scale dynamics from that of the physical processes in these biases, simulations are performed with the LMDZ general circulation model in which the horizontal winds are nudged toward reanalysis. Wind nudging greatly improves the position of the ITCZ as well as the representation of the components of the surface energy budget directly impacted by the water budget and hence facilitates a more systematic analysis of remaining biases associated with the physics in the model. The great potential of wind nudging to compare the energetics of the atmospheric column in climate models at grid cell scale with station observations, even for coarse grid models, is then shown. Despite the improved water advection and rainfall seasonality in the nudged simulations, errors consisting in a cold bias during the dry season over Sahel, an underestimated seasonal variation of surface albedo, and an overestimation of the solar incoming flux remain. The origin of these remaining biases is further investigated by conducting a series of dedicated sensitivity experiments. Results highlight the key role of the soil thermal inertia, the turbulent mixing efficiency, the surface albedo, and the aerosols and clouds radiative effects in the representation of meteorological 2m-variables and surface energy budget. © 2017. The Authors."
"57003541400;25222135800;57191172160;7403116226;57205189680;","A 2000-year history of disturbance and recovery at a sacred site in Peru’s northeastern cloud forest",2017,"10.1177/0959683617702232","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033480212&doi=10.1177%2f0959683617702232&partnerID=40&md5=fb6b98b0fc0273ef09235fdbf67253f7","The last 2000 years in the tropical Andes was both a time of major pre-Hispanic and Hispanic period cultural developments, and increased climate variability. From c. AD 1000, Andean societies underwent significant transformation and many sites previously integrated under imperial Wari hegemony were abandoned. It has been argued that this sociopolitical reorganization was, in part, a response to the heightened climate variability of the late-Holocene. Here, we present a 2000-year diatom record from the cloud forest setting of Laguna de los Condores, in the Peruvian Andes. Cliff tombs overlooking the lake and a nearby abandoned village form one of the most important archaeological complexes in the Peruvian Chachapoyas region. The presence of diatoms that indicate high productivity (e.g. Planothidium frequentissimum and Amphora pediculus) from as early as 2000 cal. yr BP suggest the lake was impacted by human activity predating the construction of monumental architecture and the regional Chachapoya cultural identity. The diatom fauna is consistent with sediment geochemical evidence that suggests high terrigenous input during the same period that would indicate that the surrounding catchment was disturbed. After c. AD 900 (1050 cal. yr BP), the diatom assemblage becomes dominated by species more indicative of a less productive system, coincident with a declining sedimentation rate, and a decrease in total biogenic silica: conditions that persist to modern times. The transition from a lake with high productivity receiving high erosional input to a less productive more stable system is contemporaneous with an increase in archaeologically documented mortuary and settlement activity. This period of declining terrigenous input is at odds with regional climate, which suggests a wetter than average period. Our data suggest the occupants of Laguna de los Condores changed their land use practices, as the region became wetter, and, in so doing, reduced erosion around the lake. © 2017, © The Author(s) 2017."
"55800795200;56073604200;55834717600;24173130300;6507785309;","Evaluation of WRF SCM Simulations of Stratocumulus-Topped Marine and Coastal Boundary Layers and Improvements to Turbulence and Entrainment Parameterizations",2017,"10.1002/2017MS001092","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034213543&doi=10.1002%2f2017MS001092&partnerID=40&md5=84c038ca2d57cfab0d0eebae978dd12a","Stratocumulus-topped boundary layers (STBLs) are notoriously difficult to parameterize in single-column models due to the strong inversion layer across which entrainment mixing plays an important role in modulating the boundary layer mass, energy, and moisture balances. We compare three different WRF planetary boundary layer (PBL) schemes (Yonsei University, YSU; Asymmetric Convective Model version 2, ACM2; Mellor-Yamada-Nakanishi-Niino, MYNN) against large eddy simulations (LES) to find out that they underestimate entrainment flux in stratocumulus over both ocean and coastal land. Hence, the PBL schemes produce a cooler, moister STBL with higher liquid water content. In order to improve the entrainment parameterization, we propose a modification to the YSU scheme that takes into account the in-cloud turbulence flux contribution to cloud top entrainment through the formulation of a velocity scale based on the in-cloud buoyancy flux. A revised top-down mixing profile is also implemented to model mixing due to turbulence generated by longwave cooling at the cloud top. The modified YSU simulates stronger entrainment flux, resulting in a STBL that matches LES results. Similar modifications were made to ACM2 in addition to implementing explicit entrainment, and while the results also showed good agreement with LES, discretization issues and conflicts with its original design prevent immediate implementation, as the contribution from the modifications and the original scheme are difficult to correctly modulate. © 2017. The Authors."
"55701929500;22952808500;23034090000;55701823500;55954463000;57201304604;6603501932;7004854247;14625176400;7102578362;","Optimal climate for large trees at high elevations drives patterns of biomass in remote forests of Papua New Guinea",2017,"10.1111/gcb.13741","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019772535&doi=10.1111%2fgcb.13741&partnerID=40&md5=c538f890424d8afcc462a02e7ffc3cb3","Our ability to model global carbon fluxes depends on understanding how terrestrial carbon stocks respond to varying environmental conditions. Tropical forests contain the bulk of the biosphere's carbon. However, there is a lack of consensus as to how gradients in environmental conditions affect tropical forest carbon. Papua New Guinea (PNG) lies within one of the largest areas of contiguous tropical forest and is characterized by environmental gradients driven by altitude; yet, the region has been grossly understudied. Here, we present the first field assessment of aboveground biomass (AGB) across three main forest types of PNG using 193 plots stratified across 3,100-m elevation gradient. Unexpectedly, AGB had no direct relationship to rainfall, temperature, soil, or topography. Instead, natural disturbances explained most variation in AGB. While large trees (diameter at breast height > 50 cm) drove altitudinal patterns of AGB, resulting in a major peak in AGB (2,200–3,100 m) and some of the most carbon-rich forests at these altitudes anywhere. Large trees were correlated to a set of climatic variables following a hump-shaped curve. The set of “optimal” climatic conditions found in montane cloud forests is similar to that of maritime temperate areas that harbor the largest trees in the world: high ratio of precipitation to evapotranspiration (2.8), moderate mean annual temperature (13.7°C), and low intra-annual temperature range (7.5°C). At extreme altitudes (2,800–3,100 m), where tree diversity elsewhere is usually low and large trees are generally rare or absent, specimens from 18 families had girths >70 cm diameter and maximum heights 20–41 m. These findings indicate that simple AGB-climate-edaphic models may not be suitable for estimating carbon storage in forests where optimal climate niches exist. Our study, conducted in a very remote area, suggests that tropical montane forests may contain greater AGB than previously thought and the importance of securing their future under a changing climate is therefore enhanced. © 2017 John Wiley & Sons Ltd"
"23492864500;7006184606;7006614696;36161790500;","Implications of Warm Rain in Shallow Cumulus and Congestus Clouds for Large-Scale Circulations",2017,"10.1007/s10712-017-9429-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030087504&doi=10.1007%2fs10712-017-9429-z&partnerID=40&md5=818c2cee1e96257ef1cbea1acd1bad81","Space-borne observations reveal that 20–40% of marine convective clouds below the freezing level produce rain. In this paper we speculate what the prevalence of warm rain might imply for convection and large-scale circulations over tropical oceans. We present results using a two-column radiative–convective model of hydrostatic, nonlinear flow on a non-rotating sphere, with parameterized convection and radiation, and review ongoing efforts in high-resolution modeling and observations of warm rain. The model experiments investigate the response of convection and circulation to sea surface temperature (SST) gradients between the columns and to changes in a parameter that controls the conversion of cloud condensate to rain. Convection over the cold ocean collapses to a shallow mode with tops near 850 hPa, but a congestus mode with tops near 600 hPa can develop at small SST differences when warm rain formation is more efficient. Here, interactive radiation and the response of the circulation are crucial: along with congestus a deeper moist layer develops, which leads to less low-level radiative cooling, a smaller buoyancy gradient between the columns, and therefore a weaker circulation and less subsidence over the cold ocean. The congestus mode is accompanied with more surface precipitation in the subsiding column and less surface precipitation in the deep convecting column. For the shallow mode over colder oceans, circulations also weaken with more efficient warm rain formation, but only marginally. Here, more warm rain reduces convective tops and the boundary layer depth—similar to Large-Eddy Simulation (LES) studies—which reduces the integrated buoyancy gradient. Elucidating the impact of warm rain can benefit from large-domain high-resolution simulations and observations. Parameterizations of warm rain may be constrained through collocated cloud and rain profiling from ground, and concurrent changes in convection and rain in subsiding and convecting branches of circulations may be revealed from a collocation of space-borne sensors, including the Global Precipitation Measurement (GPM) and upcoming Aeolus missions. © 2017, The Author(s)."
"6603287639;35334472800;6603547594;57196353254;8791306500;6701581258;7004129856;43462093500;8280398300;56246458800;8378887500;6603480361;","Denitrification, dehydration and ozone loss during the 2015/2016 Arctic winter",2017,"10.5194/acp-17-12893-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032732775&doi=10.5194%2facp-17-12893-2017&partnerID=40&md5=9c827032d8969ff412efd639c1578925","The 2015/2016 Arctic winter was one of the coldest stratospheric winters in recent years. A stable vortex formed by early December and the early winter was exceptionally cold. Cold pool temperatures dropped below the nitric acid trihydrate (NAT) existence temperature of about 195ĝ€K, thus allowing polar stratospheric clouds (PSCs) to form. The low temperatures in the polar stratosphere persisted until early March, allowing chlorine activation and catalytic ozone destruction. Satellite observations indicate that sedimentation of PSC particles led to denitrification as well as dehydration of stratospheric layers. Model simulations of the 2015/2016 Arctic winter nudged toward European Centre for Medium-Range Weather Forecasts (ECMWF) analysis data were performed with the atmospheric chemistry&ndash;climate model ECHAM5/MESSy Atmospheric Chemistry (EMAC) for the Polar Stratosphere in a Changing Climate (POLSTRACC) campaign. POLSTRACC is a High Altitude and Long Range Research Aircraft (HALO) mission aimed at the investigation of the structure, composition and evolution of the Arctic upper troposphere and lower stratosphere (UTLS). The chemical and physical processes involved in Arctic stratospheric ozone depletion, transport and mixing processes in the UTLS at high latitudes, PSCs and cirrus clouds are investigated. In this study, an overview of the chemistry and dynamics of the 2015/2016 Arctic winter as simulated with EMAC is given. Further, chemical&ndash;dynamical processes such as denitrification, dehydration and ozone loss during the 2015/2016 Arctic winter are investigated. Comparisons to satellite observations by the Aura Microwave Limb Sounder (Aura/MLS) as well as to airborne measurements with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) performed aboard HALO during the POLSTRACC campaign show that the EMAC simulations nudged toward ECMWF analysis generally agree well with observations. We derive a maximum polar stratospheric O3 loss of ĝ1/4&thinsp;2ĝ€ppmv or 117ĝ€DU in terms of column ozone in mid-March. The stratosphere was denitrified by about 4&ndash;8ĝ€ppbv HNO3 and dehydrated by about 0.6&ndash;1ĝ€ppmv H2O from the middle to the end of February. While ozone loss was quite strong, but not as strong as in 2010/2011, denitrification and dehydration were so far the strongest observed in the Arctic stratosphere in at least the past 10 years. © Author(s) 2017."
"57194056931;56091202800;36843654900;36021525100;52364737200;","Clustering of observed diurnal cycles of precipitation over the United States for evaluation of a WRF multiphysics regional climate ensemble",2017,"10.1175/JCLI-D-16-0851.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032281686&doi=10.1175%2fJCLI-D-16-0851.1&partnerID=40&md5=a8a59d6bb02891d36b829109d99624b9","The diurnal cycle of precipitation during the summer season over the contiguous United States is examined in eight distinct regions. These were identified using cluster analysis applied to the diurnal cycle characteristics at 2141 rainfall gauges over the 10-yr period 1991-2000. Application of the clustering technique provides a physically meaningful way of identifying regions for comparison of model results with observations. The diurnal cycle for each region is specified in terms of 1) total precipitation, 2) frequency of precipitation occurrence, and 3) intensity of precipitation per occurrence on an hourly basis averaged over the 10-yr period. The amplitude and phase of each element of the diurnal cycle was obtained from harmonic analysis and has been compared with the results of a 24-member multiphysics ensemble of simulations produced by the Weather Research and Forecast (WRF) Model on a region-by-region basis. Three cumulus schemes, two radiation schemes, two microphysics schemes, and two planetary boundary layer schemes were included in the ensemble. Simulations of total precipitation showed reasonable agreement with observations in regions where the diurnal cycle is directly influenced by solar radiation, (e.g., the U.S. Southeast), but they were less successful in regions where other factors influence the diurnal cycle (e.g., the central United States). The diurnal cycle of precipitation frequency and intensity showed substantial biases in the simulations of all eight regions, namely, overestimation of occurrences and underestimation of intensities. Simulations were sensitive to the cumulus and radiation schemes but were largely insensitive to either microphysics or planetary boundary layer schemes. © 2017 American Meteorological Society."
"57197786288;24177361900;","Potential vorticity diagnostics to quantify effects of latent heating in extratropical cyclones. Part I: Methodology",2017,"10.1175/JAS-D-17-0041.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034782511&doi=10.1175%2fJAS-D-17-0041.1&partnerID=40&md5=fceee89e98850bdc2bd7f7a0f9a7256b","Extratropical cyclones develop because of baroclinic instability, but their intensification is often substantially amplified by diabatic processes, most importantly, latent heating (LH) through cloud formation. Although this amplification is well understood for individual cyclones, there is still need for a systematic and quantitative investigation of how LH affects cyclone intensification in different, particularly warmer and moister, climates. For this purpose, the authors introduce a simple diagnostic to quantify the contribution of LH to cyclone intensification within the potential vorticity (PV) framework. The two leading terms in the PV tendency equation, diabatic PV modification and vertical advection, are used to derive a diagnostic equation to explicitly calculate the fraction of a cyclone's positive lower-tropospheric PV anomaly caused by LH. The strength of this anomaly is strongly coupled to cyclone intensity and the associated impacts in terms of surface weather. To evaluate the performance of the diagnostic, sensitivity simulations of 12 Northern Hemisphere cyclones with artificially modified LH are carried out with a numerical weather prediction model. Based on these simulations, it is demonstrated that the PV diagnostic captures the mean sensitivity of the cyclones' PV structure to LH as well as parts of the strong case-to-case variability. The simple and versatile PV diagnostic will be the basis for future climatological studies of LH effects on cyclone intensification. © 2017 American Meteorological Society."
"57195546621;6506011020;24467868900;55939316400;26423375600;23007415000;7004580125;","Trends in phenological parameters and relationship between land surface phenology and climate data in the hyrcanian forests of Iran",2017,"10.1109/JSTARS.2017.2736938","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028705334&doi=10.1109%2fJSTARS.2017.2736938&partnerID=40&md5=174a9bbc0612a5a512e4628923ac77a5","Vegetation activity may be changed in response to climate variability by affecting seasonality and phenological events. Monitoring of land surface phenological changes play a key role in understanding feedback of ecosystem dynamics. This study focuses on the analysis of trends in land surface phenology derived parameters using normalized difference vegetation index time series based on Global Inventory Monitoring and Mapping Studies data in the Hyrcanian forests of Iran covering the period 1981-2012. First, we applied interpolation for data reconstruction in order to remove outliers and cloud contamination in time series. Phenological parameters were retrieved by using the midpoint approach, whereas trends were estimated using the Theil-Sen approach. Correlation coefficients were evaluated from multiple linear regression between phenological parameters against temperature and precipitation time series. Significant Mann-Kendall test analysis indicate average start of season (SOS) and end of season (EOS) increased by -0.16 and +0.14 days per year, respectively. Results of significant trend analysis showed that later EOS was associated with increasing temperature trends and we found strongest relationships between temperature and phenological parameters in the west of the Hyrcanian forests, where precipitation was abundant. Moreover, SOS correlated strongly with total precipitation and mean temperature. This study allows us to better estimate the drivers affecting the vegetation dynamics in the Hyrcanian forests of Iran. © 2008-2012 IEEE."
"57193015007;35743348300;55642592500;7005133082;","Spatiotemporal multiresolution modeling to infill missing areal data and enhance the temporal frequency of infrared satellite images",2017,"10.1002/env.2466","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028769802&doi=10.1002%2fenv.2466&partnerID=40&md5=a7391ab70c1187e445e8dd5f771cb4b8","High-resolution environmental observations from satellite remote sensing are useful for gaining insight into climate variability over large regions of the earth. However, data products derived from infrared remote sensing can have large amounts of missing data due to periodic cloud cover obscuring the earth's surface. In addition, these products are commonly derived from instruments aboard polar-orbiting satellites, which make relatively infrequent passes over each region of the planet, leaving large blocks of data that are missing in time. The goal of this research is to overcome these issues by spatially and temporally infilling temperature data using satellite observations. To accomplish this, we propose novel statistical modeling techniques to account for dissonance between the areal spatial support of the data and the continuous temporal domain. In addition, we develop a novel multiresolution approach that accommodates the large spatial dimensionality of high-resolution satellite images. The result of our work is a computationally efficient methodology that provides the means to infill satellite data products both spatially and temporally. The methodology is demonstrated using land surface temperature fields from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard NASA's Terra and Aqua satellites, over Harris County, Texas, USA. Copyright © 2017 John Wiley & Sons, Ltd."
"16202694600;7004060399;","Understanding the time scales of the tropospheric circulation response to abrupt CO2 forcing in the Southern Hemisphere: Seasonality and the role of the stratosphere",2017,"10.1175/JCLI-D-16-0849.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032216614&doi=10.1175%2fJCLI-D-16-0849.1&partnerID=40&md5=04491cf081423b03c8049a79e4498586","This study examines the time scales of the Southern Hemisphere (SH) tropospheric circulation response to increasing atmospheric CO2 concentrations in models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). In response to an abrupt quadrupling of atmospheric CO2, the midlatitude jet stream and poleward edge of the Hadley circulation shift poleward on the time scale of the rising global-mean surface temperature during the summer and fall seasons but on a much more rapid time scale during the winter and spring seasons. The seasonally varying time scales of the SH circulation response are closely tied to the meridional temperature gradient in the upper troposphere-lower stratosphere and, in particular, to temperatures in the SH polar lower stratosphere. During summer and fall, SH polar lower-stratospheric temperatures cool on the time scale of warming global surface temperatures, as the lifting of the tropopause height with tropospheric warming is associated with cooling at lower-stratospheric levels. However, during winter and spring, SH polar lower-stratospheric temperatures cool primarily from fast time-scale radiative processes, contributing to the faster time-scale circulation response during these seasons. The poleward edge of the SH subtropical dry zone shifts poleward on the time scale of the rising global-mean surface temperature during all seasons in response to an abrupt quadrupling of atmospheric CO2. The dry zone edge initially follows the poleward shift in the Hadley cell edge but is then augmented by the action of eddy moisture fluxes in a warming climate. Consequently, with increasing atmospheric CO2 concentrations, key features of the tropospheric circulation response could emerge sooner than features more closely tied to rising global temperatures. © 2017 American Meteorological Society."
"56179532000;55681862500;55482033300;7403974748;","Human-biometeorological assessment of increasing summertime extreme heat events in Shanghai, China during 1973–2015",2017,"10.1007/s00704-016-1933-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988700475&doi=10.1007%2fs00704-016-1933-4&partnerID=40&md5=3b926753f54a38bcf45ed0f8821a8161","Summertime extreme heat events, defined by the Universal Thermal Climate Index (UTCI), have shown increasing trends in Shanghai from 1973 to 2015. There is a clear shift to higher temperatures for the daily maximum UTCI values, and the number of days with daily maximum UTCI exceeding 38 °C significantly increased by 4.34 days/10a. An upward trend of 3.67 days/10a was detected for the number of hot days which also displays an abrupt increase around 1998. Both the frequency and total duration of heat waves have significantly increased by 0.77 times/10a and 3.51 days/10a respectively. Their inter-decadal variations indicate a three-part division of the study period showing more and more heat waves and longer total duration, which are 1.0 times/a and 4.13 days/a for 1973–1987, 1.71 times/a and 7.64 days/a for 1988–2001, and 3.57 times/a and 16.0 days/a for 2002–2015. In addition to that are more occurrences of long-lasting heat waves. Compared with the UTCI, air temperature-based definitions have indicated substantially higher increases in extreme heat events, especially for hot nights. The relatively low humidity and strong wind speeds in the twenty-first century are considered to be responsible for this difference. Our study provides a more in-depth case to monitor extreme heat events under the combining effects of air temperature, humidity, wind speeds, total cloud cover, etc. and can support studies over other regions. © 2016, Springer-Verlag Wien."
"7401900092;7006518289;7202699757;44261604800;36716326600;7003539477;7006193614;56685916900;","Decadal variability of the Indian and Pacific walker cells since the 1960s: Do they covary on decadal time scales?",2017,"10.1175/JCLI-D-16-0783.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032210571&doi=10.1175%2fJCLI-D-16-0783.1&partnerID=40&md5=f74715e31700868ab7608c467ffc448f","Previous studies have investigated the centennial and multidecadal trends of the Pacific and Indian Ocean Walker cells (WCs) during the past century, but have obtained no consensus owing to data uncertainties and weak signals of the long-term trends. This paper focuses on decadal variability (periods of one to few decades) by first documenting the variability of the WCs and warm-pool convection, and their covariability since the 1960s, using in situ and satellite observations and reanalysis products. The causes for the variability and covariability are then explored using a Bayesian dynamic linear model, which can extract nonstationary effects of climate modes. The warm-pool convection exhibits apparent decadal variability, generally covarying with the Indian and Pacific Ocean WCs during winter (November-April) with enhanced convection corresponding to intensified WCs, and the Indian-Pacific WCs covary. During summer (May-October), the warm-pool convection still highly covaries with the Pacific WC but does not covary with the Indian Ocean WC, and the Indian-Pacific WCs are uncorrelated. The wintertime coherent variability results from the vital influence of ENSO decadal variation, which reduces warm-pool convection and weakens the WCs during El Niño-like conditions. During summer, while ENSO decadal variability still dominates the Pacific WC, decadal variations of ENSO, the Indian Ocean dipole, Indian summer monsoon convection, and tropical Indian Ocean SST have comparable effects on the Indian Ocean WC overall, with monsoon convection having the largest effect since the 1990s. The complex causes for the Indian Ocean WC during summer result in its poor covariability with the Pacific WC and warm-pool convection. © 2017 American Meteorological Society."
"55537426400;6603196127;16480666100;","The role of atmospheric heat transport and regional feedbacks in the Arctic warming at equilibrium",2017,"10.1007/s00382-017-3523-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009727215&doi=10.1007%2fs00382-017-3523-2&partnerID=40&md5=44ee4f98ed27710e759291f73bd08ca0","It is well known that the Arctic warms much more than the rest of the world even under spatially quasi-uniform radiative forcing such as that due to an increase in atmospheric CO2 concentration. While the surface albedo feedback is often referred to as the explanation of the enhanced Arctic warming, the importance of atmospheric heat transport from the lower latitudes has also been reported in previous studies. In the current study, an attempt is made to understand how the regional feedbacks in the Arctic are induced by the change in atmospheric heat transport and vice versa. Equilibrium sensitivity experiments that enable us to separate the contributions of the Northern Hemisphere mid-high latitude response to the CO2 increase and the remote influence of surface warming in other regions are carried out. The result shows that the effect of remote forcing is predominant in the Arctic warming. The dry-static energy transport to the Arctic is reduced once the Arctic surface warms in response to the local or remote forcing. The feedback analysis based on the energy budget reveals that the increased moisture transport from lower latitudes, on the other hand, warms the Arctic in winter more effectively not only via latent heat release but also via greenhouse effect of water vapor and clouds. The change in total atmospheric heat transport determined as a result of counteracting dry-static and latent heat components, therefore, is not a reliable measure for the net effect of atmospheric dynamics on the Arctic warming. The current numerical experiments support a recent interpretation based on the regression analysis: the concurrent reduction in the atmospheric poleward heat transport and future Arctic warming predicted in some models does not imply a minor role of the atmospheric dynamics. Despite the similar magnitude of poleward heat transport change, the Arctic warms more than the Southern Ocean even in the equilibrium response without ocean dynamics. It is shown that a large negative shortwave cloud feedback over the Southern Ocean, greatly influenced by low-latitude surface warming, is responsible for this asymmetric polar warming. © 2017, Springer-Verlag Berlin Heidelberg."
"57192087588;7004326151;7202244409;","An evaluation of monthly impervious surface dynamics by fusing Landsat and MODIS time series in the Pearl River Delta, China, from 2000 to 2015",2017,"10.1016/j.rse.2017.08.036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029361727&doi=10.1016%2fj.rse.2017.08.036&partnerID=40&md5=132f4cbe8de630e5289f2d54bb8dc31c","Researchers have been attending increasingly to impervious surface dynamics to better understand the urbanization process and its impacts on urban environments. Previously, numerous studies have only estimated and mapped impervious surface dynamics at annual or decadal time scales. It is challenging to estimate impervious surface dynamics at a finer time scale, such as on a monthly scale, while using a single source of medium spatial resolution satellite imagery. However, urban infrastructure construction could cause changes in impervious surfaces in a short period of time. This paper aimed at developing a new methodology for evaluating monthly impervious surface dynamics by fusing Landsat and MODIS time series. The Pearl River Delta in China, is located in a humid subtropical region and was selected as the study area due to its dramatic urbanization in the past three decades. Available Landsat images with cloud cover < 90%, 7-Day MODIS NDVI 250 m smooth time series, and daily MODIS LST 1000 m time series from 2000 to 2015 were downloaded. These data were used to develop temporal features of land covers (i.e., monthly Landsat NDVI and LST time series) and to monitor impervious surface dynamics using semi-supervised time series fuzzy clustering method. The results showed the effectiveness of temporal features in differentiating land covers. Additionally, the average overall classification accuracy yielded reasonable accuracies (up to 89.36%). The proposed methodology has illustrated numerous, considerable advantages over previous methods. It has offered consistent maps of impervious surfaces on a monthly time scale as well as enhanced distinguishability of land covers with similar spectral characteristics. This study can be utilized to establish relationships between urban expansion, climate change, urban environment, population, and other socio-economic variables on a monthly basis. The study is also crucial for predicting the timing, duration, and density of ecological change for increased impervious surfaces. © 2017 Elsevier Inc."
"57194147922;7004047492;6701498473;7102422542;","The aerosol index and land cover class based atmospheric correction aerosol optical depth time series 1982-2014 for the SMAC algorithm",2017,"10.3390/rs9111095","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034761031&doi=10.3390%2frs9111095&partnerID=40&md5=78ba02ca343ca03abf970ec0ed518e7f","Atmospheric effects, especially aerosols, are a significant source of uncertainty for optical remote sensing of surface parameters, such as albedo. Also to achieve a homogeneous surface albedo time series, the atmospheric correction has to be homogeneous. However, a global homogeneous aerosol optical depth (AOD) time series covering several decades did not previously exist. Therefore, we have constructed an AOD time series 1982-2014 using aerosol index (AI) data from the satellite measurements of the Total Ozone Mapping Spectrometer (TOMS) and the Ozone Monitoring Instrument (OMI), together with the Solar zenith angle and land use classification data. It is used as input for the Simplified Method for Atmospheric Correction (SMAC) algorithm when processing the surface albedo time series CLARA-A2 SAL (the Surface ALbedo from the Satellite Application Facility on Climate Monitoring project cLoud, Albedo and RAdiation data record, the second release). The surface reflectance simulations using the SMAC algorithm for different sets of satellite-based AOD data show that the aerosol-effect correction using the constructed TOMS/OMI based AOD data is comparable to using other satellite-based AOD data available for a shorter time range. Moreover, using the constructed TOMS/OMI based AOD as input for the atmospheric correction typically produces surface reflectance values closer to those obtained using in situ AOD values than when using other satellite-based AOD data. © 2017 by the authors."
"57213508524;54415303600;57214563572;56123335600;55494568400;57205707345;","Combined observation of a dust storm over the Loess Plateau using a dual-wavelength lidar and an aethalometer",2017,"10.1016/j.apr.2017.04.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019003679&doi=10.1016%2fj.apr.2017.04.010&partnerID=40&md5=de9aa2c86d2d4a0884f679ef0544d7ec","A dust storm was observed at the Semi-Arid Climate and Environment observatory of Lanzhou University (SACOL) using a dual-wavelength lidar and an aethalometer from 16 March to 22 March 2010. After the arrival of the dust storm, the lidar backscattered signal increased suddenly, the volume depolarization ratio ranged from 0.2 to 0.4. The dust aerosol was detected mainly in a layer below 2.5 km altitude. A higher attenuated backscatter coefficient (0.005–0.02 km−1/sr) was distributed in a lower layer (below 2.5 km) during the dust storm. The evolution of the dust storm was also clearly revealed by the integrated particle backscatter coefficient (BE). Particles in the coarse mode are predominant during the dust storm because Ångström exponent mainly ranged from 0.5 to 1.0. An aethalometer was used to measure the aerosol absorption coefficient as well as aerosol mass concentration. The average mass concentration of aerosol was 1.3 μg/m3 during the dust free period but increased to 1.8 μg/m3 during the dust storm, so the dust aerosol apparently played an important role. The main absorptive particle was black carbon during the dust free period. In addition, the peaks of dust aerosol concentration mainly occurred at around 08:00 and 20:00 (Beijing Time), one reason was that the increase of wind speed result in more dust particles blown up into the atmosphere in the neighborhood of SACOL and another reason was that the boundary layer convection was undeveloped in the morning and the temperature inversion appeared easily in the evening. The trend of the aerosol absorption coefficient was similar to that of mass concentration, and the aerosol absorption coefficient significantly increased during the dust storm. © 2017 Turkish National Committee for Air Pollution Research and Control"
"57195956298;7003352529;36844796700;6505985320;6505946652;35221145900;24476089100;6701751679;","Methodological considerations of terrestrial laser scanning for vegetation monitoring in the sagebrush steppe",2017,"10.1007/s10661-017-6300-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032000605&doi=10.1007%2fs10661-017-6300-0&partnerID=40&md5=0e3e69f418c3c6aa42927710ca75f42a","Terrestrial laser scanning (TLS) provides fast collection of high-definition structural information, making it a valuable field instrument to many monitoring applications. A weakness of TLS collections, especially in vegetation, is the occurrence of unsampled regions in point clouds where the sensor’s line-of-sight is blocked by intervening material. This problem, referred to as occlusion, may be mitigated by scanning target areas from several positions, increasing the chance that any given area will fall within the scanner’s line-of-sight from at least one position. Because TLS collections are often employed in remote regions where the scope of sampling is limited by logistical factors such as time and battery power, it is important to design field protocols which maximize efficiency and support increased quantity and quality of the data collected. This study informs researchers and practitioners seeking to optimize TLS sampling methods for vegetation monitoring in dryland ecosystems through three analyses. First, we quantify the 2D extent of occluded regions based on the range from single scan positions. Second, we measure the efficacy of additional scan positions on the reduction of 2D occluded regions (area) using progressive configurations of scan positions in 1 ha plots. Third, we test the reproducibility of 3D sampling yielded by a 5-scan/ha sampling methodology using redundant sets of scans. Analyses were performed using measurements at analysis scales of 5 to 50 cm across the 1-ha plots, and we considered plots in grass and shrub-dominated communities separately. In grass-dominated plots, a center-scan configuration and 5 cm pixel size sampled at least 90% of the area up to 18 m away from the scanner. In shrub-dominated plots, sampling at least 90% of the area was only achieved within a distance of 12 m. We found that 3 and 5 scans/ha are needed to sample at least ~ 70% of the total area (1 ha) in the grass and shrub-dominated plots, respectively, using 5 cm pixels to measure sampling presence-absence. The reproducibility of 3D sampling provided by a 5 position scan layout across 1-ha plots was 50% (shrub) and 70% (grass) using a 5-cm voxel size, whereas at the 50-cm voxel scale, reproducibility of sampling was nearly 100% for all plot types. Future studies applying TLS in similar dryland environments for vegetation monitoring may use our results as a guide to efficiently achieve sampling coverage and reproducibility in datasets. © 2017, Springer International Publishing AG."
"57211647678;37021732000;55496966500;35172576100;","Impact of drought and normal monsoon scenarios on aerosol induced radiative forcing and atmospheric heating in Varanasi over middle Indo-Gangetic Plain",2017,"10.1016/j.jaerosci.2017.07.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028084593&doi=10.1016%2fj.jaerosci.2017.07.016&partnerID=40&md5=d7965586e413cf5b3b1d175104a95cca","Observations on aerosols with specific emphasis to black carbon (BC) are reported for an urban site over middle Indo-Gangetic Plain (IGP), South Asia. Emphases are made to evaluate variation in BC concentrations during typical monsoon season (June-September, JJAS) from 2009 to 2011, and to recognize its impact on aerosol radiative forcing (ARF) and atmospheric heating. Almost entire Indian sub-continent experienced a drought year in 2009 before achieving a normal monsoon in 2010 and 2011. The ground monitoring station in Varanasi over middle-IGP experienced minimum monsoonal rain during 2009 drought year (total monsoon rain: 437.3 mm), which gradually increased during 2010 (deficit monsoon, 613.4 mm), before achieving a normal monsoon in year 2011 (1207.0 mm). The BC mass loading during drought year was relatively high (mean ± SD: 7.0 ± 3.3; range: 5.3–8.8 μg m−3) compared to 2010 (4.9 ± 2.1, 3.7–5.8 μg m−3) and 2011 (4.6 ± 2.1, 3.2–5.2 μg m−3). The increase in BC aerosols especially during drought year was associated to lower wind speed and reduced rate of wet removal, which potentially enhanced BC loading in comparison to years with normal monsoon. Columnar aerosol loading in terms of aerosol optical depth (AOD) was retrieved from space-borne MODerate resolution Imaging Spectroradiometer (MODIS) sensor on-board Terra satellite. It has revealed high AOD over Varanasi during drought (2009: 1.03 ± 0.15) and deficit monsoon (2010: 1.07 ± 0.53) before being reduced during 2011 (0.89 ± 0.20). Conclusively, a radiative transfer model was run to estimate the ARF for composite aerosols for both surface (SUF), atmosphere (ATM) and top of the atmosphere (TOA). The 2009 drought year was found to have reasonably higher ATM and SUF forcing (ATM: 105; SUF: − 122 W m−2) in comparison to deficit (ATM: 61; SUF: − 88 W m−2) and normal (ATM: 67; SUF: − 89 W m−2) monsoon scenarios. The lower atmosphere heating rates during 2009 monsoon was also recorded to be as high as 2.9 K day−1 in comparison to 2010 (1.7 K day−1) and 2011 (1.9 K day−1). Such findings provide meaningful outcomes in terms of climatic effects of BC aerosols and their associated inference on Indian summer monsoon. Capsule BC induced aerosol radiative forcing during 2009 drought year was higher in comparison to deficit (2010) and normal (2011) monsoon scenarios over middle IGP. © 2017 Elsevier Ltd"
"30667558200;11940329900;54893098900;","On the Dependence of Cloud Feedbacks on Physical Parameterizations in WRF Aquaplanet Simulations",2017,"10.1002/2017GL074820","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034025810&doi=10.1002%2f2017GL074820&partnerID=40&md5=b54e02f55e204d838a7eeeb45015e615","We investigate the effects of physical parameterizations on cloud feedback uncertainty in response to climate change. For this purpose, we construct an ensemble of eight aquaplanet simulations using the Weather Research and Forecasting (WRF) model. In each WRF-derived simulation, we replace only one parameterization at a time while all other parameters remain identical. By doing so, we aim to (i) reproduce cloud feedback uncertainty from state-of-the-art climate models and (ii) understand how parametrizations impact cloud feedbacks. Our results demonstrate that this ensemble of WRF simulations, which differ only in physical parameterizations, replicates the range of cloud feedback uncertainty found in state-of-the-art climate models. We show that microphysics and convective parameterizations govern the magnitude and sign of cloud feedbacks, mostly due to tropical low-level clouds in subsidence regimes. Finally, this study highlights the advantages of using WRF to analyze cloud feedback mechanisms owing to its plug-and-play parameterization capability. ©2017. American Geophysical Union. All Rights Reserved."
"55832509400;25637373000;56744297600;7403573190;","Climate Impacts of CALIPSO-Guided Corrections to Black Carbon Aerosol Vertical Distributions in a Global Climate Model",2017,"10.1002/2017GL074652","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034045238&doi=10.1002%2f2017GL074652&partnerID=40&md5=6ed15ecfc40ca38c48fc31e3dc5a1d7a","We alleviate the bias in the tropospheric vertical distribution of black carbon aerosols (BC) in the Community Atmosphere Model (CAM4) using the Cloud-Aerosol and Infrared Pathfinder Satellite Observations (CALIPSO)-derived vertical profiles. A suite of sensitivity experiments are conducted with 1x, 5x, and 10x the present-day model estimated BC concentration climatology, with (corrected, CC) and without (uncorrected, UC) CALIPSO-corrected BC vertical distribution. The globally averaged top of the atmosphere radiative flux perturbation of CC experiments is ∼8–50% smaller compared to uncorrected (UC) BC experiments largely due to an increase in low-level clouds. The global average surface temperature increases, the global average precipitation decreases, and the ITCZ moves northward with the increase in BC radiative forcing, irrespective of the vertical distribution of BC. Further, tropical expansion metrics for the poleward extent of the Northern Hemisphere Hadley cell (HC) indicate that simulated HC expansion is not sensitive to existing model biases in BC vertical distribution. ©2017. American Geophysical Union. All Rights Reserved."
"57197710245;16202694600;","The Response of Local Precipitation and Sea Level Pressure to Hadley Cell Expansion",2017,"10.1002/2017GL075380","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034032045&doi=10.1002%2f2017GL075380&partnerID=40&md5=08bbe495406a3d7b0e9f10feab31351f","Numerous lines of observational evidence suggest that Earth's tropical belt has expanded over the past 30–40 years. It is natural to expect that this poleward displacement should be associated with drying on the poleward margins of the subtropics, but it is less clear to what degree the drying should be zonally symmetric. This study tests the degree to which poleward motion of the Hadley cell boundary is associated with changes in local precipitation or sea level pressure and the degree to which those changes are zonally symmetric. Evidence from both reanalysis data and global climate models reveals that the local changes associated with Hadley cell expansion are mostly confined to certain centers of action which lie primarily over oceans. Consequently, the tropical expansion measured by zonally averaged variables is not associated with systematic drying over subtropical land regions, as is often assumed. ©2017. American Geophysical Union. All Rights Reserved."
"36553486200;57196143493;","Differential Radiative Heating Drives Tropical Atmospheric Circulation Weakening",2017,"10.1002/2017GL075678","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031712492&doi=10.1002%2f2017GL075678&partnerID=40&md5=ddb17c0f104d109fb43715cf4b9c9d6f","The tropical atmospheric circulation is projected to weaken during global warming, although the mechanisms that cause the weakening remain to be elucidated. We hypothesize that the weakening is related to the inhomogeneous distribution of the radiative forcing and feedback, which heats the tropical atmosphere in the ascending and subsiding regions differentially and thus requires the circulation to weaken due to energetic constraints. We test this hypothesis in a series of numerical experiments using a fully coupled general circulation model (GCM), in which the radiative forcing distribution is controlled using a novel method. The results affirm the effect of inhomogeneous forcing on the tropical circulation weakening, and this effect is greatly amplified by radiative feedback, especially that of clouds. In addition, we find that differential heating explains the intermodel differences in tropical circulation response to CO2 forcing in the GCM ensemble of the Climate Model Intercomparison Project. ©2017. American Geophysical Union. All Rights Reserved."
"36514096400;7403247998;35601880000;35388360600;","A Hydrometeorological Perspective on the Karakoram Anomaly Using Unique Valley-Based Synoptic Weather Observations",2017,"10.1002/2017GL075284","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032300347&doi=10.1002%2f2017GL075284&partnerID=40&md5=2c80cf5e9749fcd22ad6306539508b09","Glaciers in the eastern Hindukush, western Karakoram, and northwestern Himalayan mountain ranges of Northern Pakistan are not responding to global warming in the same manner as their counterparts elsewhere. Their retreat rates are less than the global average, and some are either stable or growing. Various investigations have questioned the role of climatic factors in regard to this anomalous behavior, widely referred to as “The Karakoram Anomaly.” Here, for the first time, we present a hydrometeorological perspective based on five decades of synoptic weather observations collected by the meteorological network of Pakistan. Analysis of this unique data set indicates that increased regional scale humidity, cloud cover, and precipitation, along with decreased net radiation, near-surface wind speed, potential evapotranspiration, and river flow, especially during the summer season, represent a substantial change in the energy, mass, and momentum fluxes that are facilitating the establishment of the Karakoram anomaly. ©2017. American Geophysical Union. All Rights Reserved."
"35189498000;55917291500;15122248200;","Constraining the Global Ocean Heat Content Through Assimilation of CERES-Derived TOA Energy Imbalance Estimates",2017,"10.1002/2017GL075396","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032180722&doi=10.1002%2f2017GL075396&partnerID=40&md5=bb031b65ad34ee23948d41876c3dada1","The Earth's energy imbalance (EEI) is stored in the oceans for the most part. Thus, estimates of its variability can be ingested in ocean retrospective analyses to constrain the global ocean heat budget. Here we propose a scheme to assimilate top of the atmosphere global radiation imbalance estimates from Clouds and the Earth's Radiant Energy System (CERES) in a coarse-resolution variational ocean reanalysis system (2000–2014). The methodology proves able to shape the heat content tendencies according to the EEI estimates, without compromising the reanalysis accuracy. Spurious variability and underestimation (overestimation) present in experiments with in situ (no) data assimilation disappear when EEI data are assimilated. The warming hiatus present without the assimilation of EEI data is mitigated, inducing ocean warming at depths below 1,500 m and slightly larger in the Southern Hemisphere, in accordance with recent studies. Furthermore, the methodology may be applied to Earth System reanalyses and climate simulations to realistically constrain the global energy budget. ©2017. American Geophysical Union. All Rights Reserved."
"56735478500;55628589750;56531367400;6701410329;57192064467;","On the Influence of Air Mass Origin on Low-Cloud Properties in the Southeast Atlantic",2017,"10.1002/2017JD027184","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038015359&doi=10.1002%2f2017JD027184&partnerID=40&md5=506612bd1ff7e8d232ac23669276311e","This study investigates the impact of air mass origin and dynamics on cloud property changes in the Southeast Atlantic (SEA) during the biomass burning season. The understanding of clouds and their determinants at different scales is important for constraining the Earth's radiative budget and thus prominent in climate system research. In this study, the thermodynamically stable SEA stratocumulus cover is observed not only as the result of local environmental conditions but also as connected to large-scale meteorology by the often neglected but important role of spatial origins of air masses entering this region. In order to assess to what extent cloud properties are impacted by aerosol concentration, air mass history, and meteorology, a Hybrid Single-Particle Lagrangian Integrated Trajectory cluster analysis is conducted linking satellite observations of cloud properties (Spinning-Enhanced Visible and Infrared Imager), information on aerosol species (Monitoring Atmospheric Composition and Climate), and meteorological context (ERA-Interim reanalysis) to air mass clusters. It is found that a characteristic pattern of air mass origins connected to distinct synoptical conditions leads to marked cloud property changes in the southern part of the study area. Long-distance air masses are related to midlatitude weather disturbances that affect the cloud microphysics, especially in the southwestern subdomain of the study area. Changes in cloud effective radius are consistent with a boundary layer deepening and changes in lower tropospheric stability (LTS). In the southeastern subdomain cloud cover is controlled by a generally higher LTS, while air mass origin plays a minor role. This study leads to a better understanding of the dynamical drivers behind observed stratocumulus cloud properties in the SEA and frames potentially interesting conditions for aerosol-cloud interactions. ©2017. American Geophysical Union. All Rights Reserved."
"57190116702;35454141800;55495496100;8067118800;30667558200;9838847000;57208601312;7005602760;6603819181;","Development of Algorithm for Discriminating Hydrometeor Particle Types With a Synergistic Use of CloudSat and CALIPSO",2017,"10.1002/2017JD027113","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031696647&doi=10.1002%2f2017JD027113&partnerID=40&md5=485eb7ab7555c2007e83ee9dab3398c6","We developed a method for classifying hydrometeor particle types, including cloud and precipitation phase and ice crystal habit, by a synergistic use of CloudSat/Cloud Profiling Radar (CPR) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)/Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP). We investigated how the cloud phase and ice crystal habit characterized by CALIOP globally relate with radar reflectivity and temperature. The global relationship thus identified was employed to develop an algorithm for hydrometeor type classification with CPR alone. The CPR-based type classification was then combined with CALIPSO-based type characterization to give CPR-CALIOP synergy classification. A unique aspect of this algorithm is to exploit and combine the lidar's sensitivity to thin ice clouds and the radar's ability to penetrate light precipitation to offer more complete picture of vertically resolved hydrometeor type classification than has been provided by previous studies. Given the complementary nature of radar and lidar detections of hydrometeors, our algorithm delivers 13 hydrometeor types: warm water, supercooled water, randomly oriented ice crystal (3D-ice), horizontally oriented plate (2D-plate), 3D-ice + 2D-plate, liquid drizzle, mixed-phase drizzle, rain, snow, mixed-phase cloud, water + liquid drizzle, water + rain, and unknown. The global statistics of three-dimensional occurrence frequency of each hydrometeor type revealed that 3D-ice contributes the most to the total cloud occurrence frequency (53.8%), followed by supercooled water (14.3%), 2D-plate (9.2%), rain (5.9%), warm water (5.7%), snow (4.8%), mixed-phase drizzle (2.3%), and the remaining types (4.0%). This hydrometeor type classification provides observation-based insight for climate model diagnostics in representation of cloud phase and their microphysical characteristics. ©2017. The Authors."
"57192429629;55087038900;","Temperature Control of the Variability of Tropical Tropopause Layer Cirrus Clouds",2017,"10.1002/2017JD027093","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037983408&doi=10.1002%2f2017JD027093&partnerID=40&md5=92a480135501c01d9ce71a5f6688760e","This study examines the temperature control of variability of tropical tropopause layer (TTL) cirrus clouds (i.e., clouds with bases higher than 14.5 km) by using 8 years (2006–2014) of observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC). It is found that the temporal variability of vertical structure of TTL cirrus cloud fraction averaged between 15°N and 15°S can be well explained by the vertical temperature gradient below ~17.5 km but by the local temperature above for both seasonal and interannual time scales. It is also found that the TTL cirrus cloud fraction at a given altitude is best correlated with the temperature at a higher altitude and this vertical displacement increases with a decrease of the cirrus altitude. It is shown that the TTL cirrus cloud fractions at all altitudes are significantly correlated with tropical cold point tropopause (CPT) temperature. The plausible mechanisms that might be responsible for the observed relations between TTL cirrus fraction and temperature-based variables are discussed, which include ice particle sediments, cooling associated with wave propagations, change of atmospheric stability, and vertical gradient of water vapor mixing ratio. We further examine the spatial covariability of TTL total cirrus cloud fraction and CPT temperature for the interannual time scale. It is found that the El Niño–Southern Oscillation and quasi-biennial oscillation are the leading factors in controlling the spatial variability of the TTL cirrus clouds and temperatures. ©2017. American Geophysical Union. All Rights Reserved."
"8211380400;56707853300;56900416800;7006306835;57192695511;56888211000;","Adverse effects of increasing drought on air quality via natural processes",2017,"10.5194/acp-17-12827-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032618253&doi=10.5194%2facp-17-12827-2017&partnerID=40&md5=d9add8196c13f86cf9542478911cdcd2","Drought is a recurring extreme of the climate system with well-documented impacts on agriculture and water resources. The strong perturbation of drought to the land biosphere and atmospheric water cycle will affect atmospheric composition, the nature and extent of which are not well understood. Here we present observational evidence that US air quality is significantly correlated with drought severity. Severe droughts during the period of 1990.2014 were found associated with growth-season (March.October) mean enhancements in surface ozone and PM2.5 of 3.5 ppbv (8 %) and 1.6 Êgm..3 (17 %), respectively. The pollutant enhancements associated with droughts do not appear to be affected by the decreasing trend of US anthropogenic emissions, indicating natural processes as the primary cause. Elevated ozone and PM2.5 are attributed to the combined effects of drought on deposition, natural emissions (wildfires, biogenic volatile organic compounds (BVOCs), and dust), and chemistry. Most climate.chemistry models are not able to reproduce the observed correlations of ozone and PM2.5 to drought severity. The model deficiencies are partly attributed to the lack of drought-induced changes in land.atmosphere exchanges of reactive gases and particles and misrepresentation of cloud changes under drought conditions. By applying the observed relationships between drought and air pollutants to climate model projected drought occurrences, we estimate an increase of 1.6% for ground-level O3 and 1. 16% for PM2.5 in the US by 2100 compared to the 2000s due to increasing drought alone. Drought thus poses an important aspect of climate change penalty on air quality, and a better prediction of such effects would require improvements in model processes. © 2017 Author(s)."
"7004050581;7004932211;12041152300;7004423756;","Diurnal Cycle Variability of Surface Temperature Inferred From AIRS Data",2017,"10.1002/2016JD026265","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032266424&doi=10.1002%2f2016JD026265&partnerID=40&md5=1034b922f616257a04ee2fd1fda38a32","The diurnal cycle of the Earth surface temperature is investigated using the daily range of the satellite skin temperature data (DTR) provided by measurements of Atmospheric Infrared Sounder (AIRS) in 2002–2015. The AIRS is on the Aqua satellite, which is in a polar orbit with two crossing times per day at every location on the Earth. Its measurements from the ascending (day) and descending (night) orbits can serve as a proxy for the diurnal cycle. The spatial pattern of the DTR of the skin temperature and its time variability for 14 years of the AIRS operation allows to evaluate the diurnal cycle change on the decadal time scale. Using the empirical mode decomposition of the data time series, it is found that the DTR of the surface (skin) temperature over the global Earth has a temporal small positive trend in the decade of the AIRS measurements indicating that the day temperatures grew slightly more rapidly than the night temperatures. A possible cause of the observed DTR increase is a decrease of the low cloud fraction at nighttime found for the same time period from the AIRS retrievals. Published 2017. This article is a U.S. Government work and is in the public domain in the USA."
"8891521600;7202069518;7406061582;36118350700;","The effects of different footprint sizes and cloud algorithms on the top-of-atmosphere radiative flux calculation from the Clouds and Earth's Radiant Energy System (CERES) instrument on Suomi National Polar-orbiting Partnership (NPP)",2017,"10.5194/amt-10-4001-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032625139&doi=10.5194%2famt-10-4001-2017&partnerID=40&md5=d8019651f1d4d7b0935612d6587677d0","Only one Clouds and Earth's Radiant Energy System (CERES) instrument is onboard the Suomi National Polar-orbiting Partnership (NPP) and it has been placed in cross-track mode since launch; it is thus not possible to construct a set of angular distribution models (ADMs) specific for CERES on NPP. Edition 4 Aqua ADMs are used for flux inversions for NPP CERES measurements. However, the footprint size of NPP CERES is greater than that of Aqua CERES, as the altitude of the NPP orbit is higher than that of the Aqua orbit. Furthermore, cloud retrievals from the Visible Infrared Imaging Radiometer Suite (VIIRS) and the Moderate Resolution Imaging Spectroradiometer (MODIS), which are the imagers sharing the spacecraft with NPP CERES and Aqua CERES, are also different. To quantify the flux uncertainties due to the footprint size difference between Aqua CERES and NPP CERES, and due to both the footprint size difference and cloud property difference, a simulation is designed using the MODIS pixel-level data, which are convolved with the Aqua CERES and NPP CERES point spread functions (PSFs) into their respective footprints. The simulation is designed to isolate the effects of footprint size and cloud property differences on flux uncertainty from calibration and orbital differences between NPP CERES and Aqua CERES. The footprint size difference between Aqua CERES and NPP CERES introduces instantaneous flux uncertainties in monthly gridded NPP CERES measurements of less than 4.0Wm-2 for SW (shortwave) and less than 1.0Wm..2 for both daytime and nighttime LW (longwave). The global monthly mean instantaneous SW flux from simulated NPP CERES has a low bias of 0.4Wm..2 when compared to simulated Aqua CERES, and the root-mean-square (RMS) error is 2.2Wm-2 between them; the biases of daytime and nighttime LW flux are close to zero with RMS errors of 0.8 and 0.2Wm..2. These uncertainties are within the uncertainties of CERES ADMs. When both footprint size and cloud property (cloud fraction and optical depth) differences are considered, the uncertainties of monthly gridded NPP CERES SW flux can be up to 20Wm-2 in the Arctic regions where cloud optical depth retrievals from VIIRS differ significantly from MODIS. The global monthly mean instantaneous SW flux from simulated NPP CERES has a high bias of 1.1Wm-2 and the RMS error increases to 5.2Wm-2. LW flux shows less sensitivity to cloud property differences than SW flux, with uncertainties of about 2Wm-2 in the monthly gridded LW flux, and the RMS errors of global monthly mean daytime and nighttime fluxes increase only slightly. These results highlight the importance of consistent cloud retrieval algorithms to maintain the accuracy and stability of the CERES climate data record. © 2017 Author(s)."
"55392290000;8383395800;56495171400;35810775100;56516013500;16027966800;7005211669;","Meteoric Smoke Deposition in the Polar Regions: A Comparison of Measurements With Global Atmospheric Models",2017,"10.1002/2017JD027143","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85038030880&doi=10.1002%2f2017JD027143&partnerID=40&md5=ee0f9896343ec4bcb818d437aa014d52","The accumulation rate of meteoric smoke particles (MSPs) in ice cores—determined from the trace elements Ir and Pt, and superparamagnetic Fe particles—is significantly higher than expected from the measured vertical fluxes of Na and Fe atoms in the upper mesosphere and the surface deposition of cosmic spherules. The Whole Atmosphere Community Climate Model with the Community Aerosol and Radiation Model for Atmospheres has been used to simulate MSP production, transport, and deposition, using a global MSP input of 7.9 t d−1 based on these other measurements. The modeled MSP deposition rates are smaller than the measurements by factors of ~32 in Greenland and ~12 in Antarctica, even after reanalysis of the Ir/Pt ice core data with inclusion of a volcanic source. Variations of the model deposition scheme and use of the United Kingdom Chemistry and Aerosols model do not improve the agreement. Direct removal of MSP-nucleated polar stratospheric cloud particles to the surface gives much better agreement, but would result in an unfeasibly high rate of nitrate deposition. The unablated fraction of cosmic dust (~35 t d−1) would provide sufficient Ir and Pt to account for the Antarctic measurements, but the relatively small flux of these large (&gt;3 μm) particles would lead to greater variability in the ice core measurements than is observed, although this would be partly offset if significant fragmentation of cosmic dust particles occurred during atmospheric entry. Future directions to resolve these discrepancies between models and measurements are also discussed. ©2017. American Geophysical Union. All Rights Reserved."
"57196143493;36553486200;57188745140;","On the pattern of CO2 radiative forcing and poleward energy transport",2017,"10.1002/2017JD027221","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031682698&doi=10.1002%2f2017JD027221&partnerID=40&md5=9de9743ff6726deef9dc6d9375efbb49","A set of general circulation model experiments are conducted to analyze how the poleward energy transport (PET) is related to the spatial pattern of CO2 radiative forcing. The effects of forcing pattern are affirmed by comparing the conventional doubling CO2 experiment, in which the forcing pattern is inhomogeneous, to a set of forcing homogenization experiments, in which the top of atmosphere (TOA), surface, or atmospheric forcing distribution is homogenized respectively. In addition, we separate and compare the effects of CO2 forcing to various feedbacks on atmospheric and oceanic PETs, by using a set of radiative kernels that we have developed for both TOA and surface radiation fluxes. The results here show that both the enhancement of atmospheric PET and weakening of oceanic PET during global warming are directly driven by the meridional gradients of the CO2 forcing. Interestingly, the overall feedback effect is to reinforce the forcing effect, mainly through the cloud feedback in the case of atmospheric PET and the albedo feedback in the case of the oceanic PET. Contrary to previous studies, we find that the water vapor feedback only has a weak effect on atmospheric PET. The Arctic warming amplification, which strongly affects atmospheric PET, is sensitive to the CO2 forcing pattern. ©2017. American Geophysical Union. All Rights Reserved."
"36084340100;57193132723;33367455100;","NIR-driven Moist Upper Atmospheres of Synchronously Rotating Temperate Terrestrial Exoplanets",2017,"10.3847/1538-4357/aa8955","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032839948&doi=10.3847%2f1538-4357%2faa8955&partnerID=40&md5=0f191d60e21b27082b5015ea1906de50","H2O is a key molecule in characterizing atmospheres of temperate terrestrial planets, and observations of transmission spectra are expected to play a primary role in detecting its signatures in the near future. The detectability of H2O absorption features in transmission spectra depends on the abundance of water vapor in the upper part of the atmosphere. We study the three-dimensional distribution of atmospheric H2O for synchronously rotating Earth-sized aquaplanets using the general circulation model (GCM) ROCKE-3D, and examine the effects of total incident flux and stellar spectral type. We observe a more gentle increase of the water vapor mixing ratio in response to increased incident flux than one-dimensional models suggest, in qualitative agreement with the climate-stabilizing effect of clouds around the substellar point previously observed in GCMs applied to synchronously rotating planets. However, the water vapor mixing ratio in the upper atmosphere starts to increase while the surface temperature is still moderate. This is explained by the circulation in the upper atmosphere being driven by the radiative heating due to absorption by water vapor and cloud particles, causing efficient vertical transport of water vapor. Consistently, the water vapor mixing ratio is found to be well-correlated with the near-infrared portion of the incident flux. We also simulate transmission spectra based on the GCM outputs, and show that for the more highly irradiated planets, the H2O signatures may be strengthened by a factor of a few, loosening the observational demands for a H2O detection. © 2017. The American Astronomical Society. All rights reserved."
"7005506011;57189657484;8776168500;7402498482;7005717609;6506629850;6602464409;6507580028;23470557400;","The influence of the synoptic regime on stable water isotopes in precipitation at Dome C, East Antarctica",2017,"10.5194/tc-11-2345-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032030887&doi=10.5194%2ftc-11-2345-2017&partnerID=40&md5=fe5387e880240ffed9b36324bc579faa","The correct derivation of paleotemperatures from ice cores requires exact knowledge of all processes involved before and after the deposition of snow and the subsequent formation of ice. At the Antarctic deep ice core drilling site Dome C, a unique data set of daily precipitation amount, type, and stable water isotope ratios is available that enables us to study in detail atmospheric processes that influence the stable water isotope ratio of precipitation. Meteorological data from both automatic weather station and a mesoscale atmospheric model were used to investigate how different atmospheric flow patterns determine the precipitation parameters. A classification of synoptic situations that cause precipitation at Dome C was established and, together with back-Trajectory calculations, was utilized to estimate moisture source areas. With the resulting source area conditions (wind speed, sea surface temperature, and relative humidity) as input, the precipitation stable isotopic composition was modeled using the so-called Mixed Cloud Isotope Model (MCIM). The model generally underestimates the depletion of 18O in precipitation, which was not improved by using condensation temperature rather than inversion temperature. Contrary to the assumption widely used in ice core studies, a more northern moisture source does not necessarily mean stronger isotopic fractionation. This is due to the fact that snowfall events at Dome C are often associated with warm air advection due to amplification of planetary waves, which considerably increases the site temperature and thus reduces the temperature difference between source area and deposition site. In addition, no correlation was found between relative humidity at the moisture source and the deuterium excess in precipitation. The significant difference in the isotopic signal of hoarfrost and diamond dust was shown to disappear after removal of seasonality. This study confirms the results of an earlier study carried out at Dome Fuji with a shorter data set using the same methods."
"57191996036;36815993100;55452292200;35313639700;57213429877;56978385600;57196117536;7402400723;8437626600;","Aerosol optical properties over China from RAMS-CMAQ Model compared with CALIOP observations",2017,"10.3390/atmos8100201","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031894116&doi=10.3390%2fatmos8100201&partnerID=40&md5=db371ffdf17e22553c451cdd1c38068a","The horizontal and vertical distributions of aerosol optical properties over China in 2013-2015 were investigated using RAMS (Regional Atmospheric Modeling System)-CMAQ (Models-3 Community Multiscale Air Quality) simulations and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) observations. To better understand the performance of the RAMS-CMAQ model over China, comparisons with the ground-based Sun photometers AERONET (Aerosol Robotic Network), MODIS (Moderate Resolution Imaging Spectroradiometers) data and the on-board Lidar CALIOP were used for comprehensive evaluations, which could characterize the abilities of the model to simulate the spatial and vertical distributions of the AOD (Aerosol Optical Depth) as well as the optical properties for four seasons. Several high value areas (e.g., the Sichuan Basin, Taklamakan Desert, North China Plain, and Yangtze River Delta) were found over China during the study period, with the maximum mean AOD (CALIOP: ~0.7; RAMS-CMAQ: >1) in the Sichuan district. Compared with AODs of AERONET, both the CALIOP and RAMS-CMAQ AODs were underestimated, but the RAMS-CMAQ data show a better correlation with AERONET (AERONET vs. RAMS-CMAQ R: 0.69, AERONET vs. CALIOP R: 0.5). The correlation coefficients between RAMS-CMAQ and CALIOP are approximately 0.6 for all four seasons. The AEC (Aerosol Extinction Coefficient) vertical profiles over major cities and their cross sections exhibit two typical features: (1) most of the AEC peaks occurred in the lowest ~0.5 km, decreasing with increasing altitude; and (2) the RAMS-CMAQ AEC underestimated the region with high AODs in the northwest of China and overestimated the region with high AODs in the east-central plain and the central basin regions. The major difference in the AEC values of RAMS-CMAQ and CALIOP is mainly caused by the level of relative humidity and the hygroscopic growth effects of water-soluble aerosols, especially, in the Sichuan district. In general, both the column and vertical RAMS-CMAQ aerosol optical properties could be supplemented efficiently when satellite observations are not available or invalid over China in the applications of climate change and air pollution. © 2017 by the authors."
"56521673500;57193604426;35494005000;","The Mass-Dimensional Properties of Cirrus Clouds During TC4",2017,"10.1002/2017JD026787","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032375354&doi=10.1002%2f2017JD026787&partnerID=40&md5=590a243286354d95e301db37b0cc8b03","Remote sensing retrievals and ice microphysical parameterizations in global climate models typically use assumptions about the distribution of ice mass as a function of particle size using mass-dimensional (m-D) relationships. This study investigates the ice crystal m-D properties of tropical anvil cirrus during the Tropical Composition, Cloud and Climate Coupling Experiment (TC4) to better document the distribution of ice mass with size in this particular class of tropical ice clouds. Two optimal estimation algorithms (XIWC and MZ) are used to estimate the m-D relationship for each particle size distribution (PSD) collected in situ. The XIWC algorithm minimizes the difference between measured ice water content (IWC) and PSD calculated IWC, while the MZ algorithm minimizes the difference between measured radar reflectivity factors and those calculated from the in situ PSDs. Results from these algorithms are compared to previous studies to establish consistency of the methodologies. The XIWC results show that both parameters in the m-D relationship increase with temperature. Changes in m-D with temperature have substantial implications for remote sensing retrievals. With the prefactor varying by a factor of 5 and the exponent varying by some 16% over a typical range of ice cloud temperatures, forward modeling errors in radar reflectivity could be typically in excess of 5 dB, further suggesting that retrievals of IWC and precipitation rates from radar measurements in ice clouds be in error by factors easily exceeding 3. ©2017. American Geophysical Union. All Rights Reserved."
"57205842560;55915387400;15751436600;55927053800;6507896695;8615886200;56001297600;57203174863;","Simulation of Optical Properties and Direct and Indirect Radiative Effects of Smoke Aerosols Over Marine Stratocumulus Clouds During Summer 2008 in California With the Regional Climate Model RegCM",2017,"10.1002/2017JD026905","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032385359&doi=10.1002%2f2017JD026905&partnerID=40&md5=9fcf4bb18018a06b284170fe1bb099ab","The regional climate model RegCM has been modified to better account for the climatic effects of biomass-burning particles. Smoke aerosols are represented by new tracers with consistent radiative and hygroscopic properties to simulate the direct radiative forcing (DRF), and a new parameterization has been integrated for relating the droplet number concentration to the aerosol concentration for marine stratocumulus clouds (Sc). RegCM has been tested during the summer of 2008 over California, when extreme concentration of smoke, together with the presence of Sc, is observed. This work indicates that significant aerosol optical depth (AOD) (~1–2 at 550 nm) is related to the intense 2008 fires. Compared to Ozone Monitoring Instrument (OMI) and Moderate Resolution Imaging Spectroradiometer, the regional pattern of RegCM AOD is well represented although the magnitude is lower than satellite observations. Comparisons with Polarization and Directionality of Earth Reflectances (POLDER) above-clouds aerosol optical depth (ACAOD) show the ability of RegCM to simulate realistic ACAOD during the transport of smoke above the Pacific Ocean. The simulated single scattering albedo is ~0.90 (at 550 nm) near biomass-burning sources, consistent with OMI and POLDER, and smoke leads to shortwave heating rates ~1.5–2°K d−1. RegCM is not able to correctly resolve the daily patterns in cloud properties notably due to its coarse horizontal resolutions. However, the changes in the sign of the DRF at top of atmosphere (TOA) (negative to positive) from clear-sky to all-sky conditions is well simulated. Finally, the “aerosol-cloud” parameterization allows simulating an increase of the cloud optical depth for significant concentrations, leading to large perturbations of radiative fluxes at TOA. ©2017. American Geophysical Union. All Rights Reserved."
"57196096713;7402737522;","A globally calibrated scheme for generating daily meteorology from monthly statistics: Global-WGEN (GWGEN) v1.0",2017,"10.5194/gmd-10-3771-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031818652&doi=10.5194%2fgmd-10-3771-2017&partnerID=40&md5=0d765193ae33fa4c70982a6f19a62dd7","While a wide range of Earth system processes occur at daily and even subdaily timescales, many global vegetation and other terrestrial dynamics models historically used monthly meteorological forcing both to reduce computational demand and because global datasets were lacking. Recently, dynamic land surface modeling has moved towards resolving daily and subdaily processes, and global datasets containing daily and subdaily meteorology have become available. These meteorological datasets, however, cover only the instrumental era of the last approximately 120 years at best, are subject to considerable uncertainty, and represent extremely large data files with associated computational costs of data input/output and file transfer. For periods before the recent past or in the future, global meteorological forcing can be provided by climate model output, but the quality of these data at high temporal resolution is low, particularly for daily precipitation frequency and amount. Here, we present GWGEN, a globally applicable statistical weather generator for the temporal downscaling of monthly climatology to daily meteorology. Our weather generator is parameterized using a global meteorological database and simulates daily values of five common variables: Minimum and maximum temperature, precipitation, cloud cover, and wind speed. GWGEN is lightweight, modular, and requires a minimal set of monthly mean variables as input. The weather generator may be used in a range of applications, for example, in global vegetation, crop, soil erosion, or hydrological models. While GWGEN does not currently perform spatially autocorrelated multi-point downscaling of daily weather, this additional functionality could be implemented in future versions."
"57188729343;36106191000;6506848120;55801231800;7004557737;7103197731;57195257572;7103204204;57190209035;57204252724;8550791300;7402838215;","Classification of Arctic, midlatitude and tropical clouds in the mixed-phase temperature regime",2017,"10.5194/acp-17-12219-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026373560&doi=10.5194%2facp-17-12219-2017&partnerID=40&md5=faa0b9f13bfbd8a54bcf42263a79d828","The degree of glaciation of mixed-phase clouds constitutes one of the largest uncertainties in climate prediction. In order to better understand cloud glaciation, cloud spectrometer observations are presented in this paper, which were made in the mixed-phase temperature regime between 0 and -38°C (273 to 235K), where cloud particles can either be frozen or liquid. The extensive data set covers four airborne field campaigns providing a total of 139000 1Hz data points (38.6h within clouds) over Arctic, midlatitude and tropical regions. We develop algorithms, combining the information on number concentration, size and asphericity of the observed cloud particles to classify four cloud types: liquid clouds, clouds in which liquid droplets and ice crystals coexist, fully glaciated clouds after the Wegener-Bergeron-Findeisen process and clouds where secondary ice formation occurred. We quantify the occurrence of these cloud groups depending on the geographical region and temperature and find that liquid clouds dominate our measurements during the Arctic spring, while clouds dominated by the Wegener-Bergeron-Findeisen process are most common in midlatitude spring. The coexistence of liquid water and ice crystals is found over the whole mixed-phase temperature range in tropical convective towers in the dry season. Secondary ice is found at midlatitudes at -5 to -10°C (268 to 263K) and at higher altitudes, i.e. lower temperatures in the tropics. The distribution of the cloud types with decreasing temperature is shown to be consistent with the theory of evolution of mixed-phase clouds. With this study, we aim to contribute to a large statistical database on cloud types in the mixed-phase temperature regime. © 2017 Author(s)."
"57205984068;23995341000;56819189800;57195629037;7004289682;","Oscillations in atmospheric water above Switzerland",2017,"10.5194/acp-17-12121-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031316815&doi=10.5194%2facp-17-12121-2017&partnerID=40&md5=7f6c0ee771a9f1b6cecb46e8a7fcfafa","Cloud fraction (CF), integrated liquid water (ILW) and integrated water vapour (IWV) were continuously measured from 2004 to 2016 by the TROpospheric WAter RAdiometer (TROWARA) in Bern, Switzerland. There are indications for interannual variations of CF and ILW. A spectral analysis shows that IWV is dominated by an annual oscillation, leading to an IWV maximum of 24kg m-2 in July to August and a minimum of 8kg m-2 in February. The seasonal behaviour of CF and ILW is composed by both the annual and the semiannual oscillation. However, the annual oscillation of CF has a maximum in December while the annual oscillation of ILW has a maximum in July. The semiannual oscillations of CF and ILW are strong from 2010 to 2014. The normalized power spectra of ILW and CF show statistically significant spectral components with periods of 76, 85, 97 and 150 days. We find a similarity between the power spectra of ILW and CF with those of zonal wind at 830hPa (1.5km) above Bern. Particularly, the occurrence of higher harmonics in the CF and ILW spectra is possibly forced by the behaviour of the lower-tropospheric wind. The mean amplitude spectra of CF, ILW and IWV show increased short-term variability on timescales less than 40 days from spring to fall. We find a weekly cycle of CF and ILW from June to September with increased values on Saturday, Sunday and Monday. © 2017 Author(s)."
"57196017336;15760501200;24081640300;25522925700;57027008400;","Sunshine duration variability in Haihe River Basin, China, during 1966-2015",2017,"10.3390/w9100770","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030989152&doi=10.3390%2fw9100770&partnerID=40&md5=3dc78ca048072d2b711a2f3a0f2591d3","Sunshine can have a profound impact on the systematic change in climate elements, such as temperature and wind speed, and in turn affects many aspects of the human society. In recent years, there has been a substantial interest in the variation of sunshine duration due to the dramatic global climate change. Hence, there is a need to better understand the variation of sunshine duration in order to cope with climate change. This study aimed to analyze the variation of sunshine duration in Haihe River basin, China, and its relationship with temperature, wind speed and low-level cloudiness. The annual, seasonal and monthly changes of sunshine duration were analyzed based on the data collected from 33 meteorological stations over the Haihe River basin during 1966-2015. It is evident that the annual, seasonal and monthly sunshine duration shows a decreasing trend over time. In addition, the annual sunshine duration is lower with a higher climate tendency rate in the southern and eastern coastal regions than that in the northwestern regions. It is negatively correlated with temperature (r = -0.50) and low-level cloudiness (r = -0.29), but positively with wind speed (r = 0.61). Wind speed may be one of the important causes of the decrease of sunshine duration in the Haihe River basin during 1966-2015. These changes may have significant implications for the hydrological cycle in the area. © 2017 by the authors. Licensee MDPI, Basel, Switzerland."
"54929027200;6602158037;57196741627;6602712196;57193525377;","Comparing MODIS and near-surface vegetation indexes for monitoring tropical dry forest phenology along a successional gradient using optical phenology towers",2017,"10.1088/1748-9326/aa838c","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033661900&doi=10.1088%2f1748-9326%2faa838c&partnerID=40&md5=7253db9c69268f7a82f88255ea2f42e3","Tropical dry forests (TDFs) present strong seasonal greenness signals ideal for tracking phenology and primary productivity using remote sensing techniques. The tightly synchronized relationship these ecosystems have with water availability offer a valuable natural experiment for observing the complex interactions between the atmosphere and the biosphere in the tropics. To investigate how well the MODIS vegetation indices (normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI)) represented the phenology of different successional stages of naturally regenerating TDFs, within a widely conserved forest fragment in the semi-arid southeast of Brazil, we installed several canopy towers with radiometric sensors to produce high temporal resolution near-surface vegetation greenness indices. Direct comparison of several years of ground measurements with a combined Aqua/Terra 8 day satellite product showed similar broad temporal trends, but MODIS often suffered from cloud contamination during the onset of the growing season and occasionally during the peak growing season. The strength of the in-situ and MODIS linear relationship was greater for NDVI than for EVI across sites but varied with forest stand age. Furthermore, we describe the onset dates and duration of canopy development phases for three years of in-situ monitoring. A seasonality analysis revealed significant discrepancies between tower and MODIS phenology transitions dates, with up to five weeks differences in growing season length estimation. Our results indicate that 8 and 16 day MODIS satellite vegetation monitoring products are suitable for tracking general patterns of tropical dry forest phenology in this region but are not temporally sufficient to characterize inter-annual differences in phenology phase onset dates or changes in productivity due to mid-season droughts. Such rapid transitions in canopy greenness are important indicators of climate change sensitivity of these already endangered forest ecosystems and should be further monitored using both ground and satellite approaches. © 2017 IOP Publishing Ltd."
"15050523700;15047538100;36242447900;6602135370;36006968000;","Progress Towards Achieving the Challenge of Indian Summer Monsoon Climate Simulation in a Coupled Ocean-Atmosphere Model",2017,"10.1002/2017MS000966","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031331071&doi=10.1002%2f2017MS000966&partnerID=40&md5=68464d15ddd4c6209546417db7c4e32a","Simulation of the spatial and temporal structure of the monsoon intraseasonal oscillations (MISOs), which have effects on the seasonal mean and annual cycle of Indian summer monsoon (ISM) rainfall, remains a grand challenge for the state-of-the-art global coupled models. Biases in simulation of the amplitude and northward propagation of MISOs and related dry rainfall bias over ISM region in climate models are limiting the current skill of monsoon prediction. Recent observations indicate that the convective microphysics of clouds may be critical in simulating the observed MISOs. The hypothesis is strongly supported by high fidelity in simulation of the amplitude and space-time spectra of MISO by a coupled climate model, when our physically based modified cloud microphysics scheme is implemented in conjunction with a modified new Simple Arakawa Schubert (nSAS) convective parameterization scheme. Improved simulation of MISOs appears to have been aided by much improved simulation of the observed high cloud fraction and convective to stratiform rain fractions and resulted into a much improved simulation of the ISM rainfall, monsoon onset, and the annual cycle. © 2017. The Authors."
"6602364115;7203034123;7003390361;6508155070;6603853280;8882641700;23484340400;15739506300;8977001000;56033466400;25640569400;56230988400;36096767000;13405561000;57195644113;7005920812;54883121500;7005056279;55800756700;6603606681;6507494944;23768540500;34772240500;7403282069;","Single-Column Model Simulations of Subtropical Marine Boundary-Layer Cloud Transitions Under Weakening Inversions",2017,"10.1002/2017MS001064","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034436494&doi=10.1002%2f2017MS001064&partnerID=40&md5=5932be40aacb3ffd4f1b8c8203b46052","Results are presented of the GASS/EUCLIPSE single-column model intercomparison study on the subtropical marine low-level cloud transition. A central goal is to establish the performance of state-of-the-art boundary-layer schemes for weather and climate models for this cloud regime, using large-eddy simulations of the same scenes as a reference. A novelty is that the comparison covers four different cases instead of one, in order to broaden the covered parameter space. Three cases are situated in the North-Eastern Pacific, while one reflects conditions in the North-Eastern Atlantic. A set of variables is considered that reflects key aspects of the transition process, making use of simple metrics to establish the model performance. Using this method, some longstanding problems in low-level cloud representation are identified. Considerable spread exists among models concerning the cloud amount, its vertical structure, and the associated impact on radiative transfer. The sign and amplitude of these biases differ somewhat per case, depending on how far the transition has progressed. After cloud breakup the ensemble median exhibits the well-known “too few too bright” problem. The boundary-layer deepening rate and its state of decoupling are both underestimated, while the representation of the thin capping cloud layer appears complicated by a lack of vertical resolution. Encouragingly, some models are successful in representing the full set of variables, in particular, the vertical structure and diurnal cycle of the cloud layer in transition. An intriguing result is that the median of the model ensemble performs best, inspiring a new approach in subgrid parameterization. © 2017. The Authors."
"13006055400;7102425008;","Regime dependence of ice cloud heterogeneity – a convective life-cycle effect?",2017,"10.1002/qj.3178","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039416074&doi=10.1002%2fqj.3178&partnerID=40&md5=02f53869402ea074444e80f1d5860e39","Cloud condensate varies on scales smaller than those typically resolved by global weather and climate models. In order to accurately predict the radiative and microphysical process rates representative of the entire model grid box, the effect of the subgrid-scale heterogeneity of cloud must be taken into account. In this study, observed ice water content retrieved from A-Train satellite observations is used to explore how spatial ice condensate variability, characterized by the fractional standard deviation (FSD, the standard deviation divided by the mean), varies with cloud regime. FSD is generally lower for overcast cloud scenes, but an additional predictor based on convective activity is needed to capture the high FSD associated with more turbulent clouds and reproduce the observed latitudinal and height variations of FSD. Convective clouds that extend only a few kilometres above the freezing level are likely to be smaller at an earlier stage in their life cycle, and actively growing with a higher FSD. In contrast, more mature clouds reaching the tropopause are larger and generally have a lower variability and smaller FSD. To capture this life-cycle effect, a new parametrization is tested which uses the ratio of a model's convectively detrained condensate to the existing cloud condensate mass as a proxy for the cloud's convective life stage to highlight areas with enhanced condensate variability. The parametrization is scale-adaptive, situation-dependent and captures seasonally varying global patterns and the zonal mean vertical structure of observed ice condensate variability well. Ground-based observations obtained from five Atmospheric Radiation Measurement sites provide independent confirmation that the parametrization satisfactorily captures condensate variability in high-altitude ice clouds. © 2017 Royal Meteorological Society"
"55628587967;6507400558;55550388400;34870277200;7004978125;","Improved tropical modes of variability in the NCEP Climate Forecast System (Version 2) via a stochastic multicloud model",2017,"10.1175/JAS-D-17-0113.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031101399&doi=10.1175%2fJAS-D-17-0113.1&partnerID=40&md5=e55d012d7b03c77b9b3ccfdbeb5cff87","A stochastic multicloud model (SMCM) convective parameterization, which mimics the interactions at subgrid scales of multiple cloud types, is incorporated into the National Centers for Environmental Prediction (NCEP) Climate Forecast System, version 2 (CFSv2), model (CFSsmcm) in lieu of the preexisting simplified Arakawa-Schubert (SAS) cumulus scheme. A detailed analysis of the tropical intraseasonal variability (TISV) and convectively coupled equatorial waves (CCEW) in comparison with the original (control) model and with observations is presented here. The last 10 years of a 15-yr-long climate simulation are analyzed. Significant improvements are seen in the simulation of the Madden-Julian oscillation (MJO) and most of the CCEWs as well as the Indian summer monsoon (ISM) intraseasonal oscillation (MISO). These improvements appear in the form of improved morphology and physical features of these waves. This can be regarded as a validation of the central idea behind the SMCM according to which organized tropical convection is based on three cloud types, namely, the congestus, deep, and stratiform cloud decks, that interact with each other and form a building block for multiscale convective systems. An adequate accounting of the dynamical interactions of this cloud hierarchy thus constitutes an important requirement for cumulus parameterizations to succeed in representing atmospheric tropical variability. SAS fails to fulfill this requirement, which is evident in the unrealistic physical structures of the major intraseasonal modes simulated by CFSv2 as documented here. © 2017AmericanMeteorological Society."
"57192663547;25649175400;6602831555;","Can feedback analysis be used to uncover the physical origin of climate sensitivity and efficacy differences?",2017,"10.1007/s00382-016-3476-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007180337&doi=10.1007%2fs00382-016-3476-x&partnerID=40&md5=530659c5f215451a18bb4e739832e501","Different strengths and types of radiative forcings cause variations in the climate sensitivities and efficacies. To relate these changes to their physical origin, this study tests whether a feedback analysis is a suitable approach. For this end, we apply the partial radiative perturbation method. Combining the forward and backward calculation turns out to be indispensable to ensure the additivity of feedbacks and to yield a closed forcing-feedback-balance at top of the atmosphere. For a set of CO2-forced simulations, the climate sensitivity changes with increasing forcing. The albedo, cloud and combined water vapour and lapse rate feedback are found to be responsible for the variations in the climate sensitivity. An O3-forced simulation (induced by enhanced NOx and CO surface emissions) causes a smaller efficacy than a CO2-forced simulation with a similar magnitude of forcing. We find that the Planck, albedo and most likely the cloud feedback are responsible for this effect. Reducing the radiative forcing impedes the statistical separability of feedbacks. We additionally discuss formal inconsistencies between the common ways of comparing climate sensitivities and feedbacks. Moreover, methodical recommendations for future work are given. © 2016, The Author(s)."
"35772552100;7102953444;6602809597;6701847229;15757708600;7003748648;56253852700;35177669200;6505627012;","Projected changes in surface solar radiation in CMIP5 global climate models and in EURO-CORDEX regional climate models for Europe",2017,"10.1007/s00382-016-3471-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85004065506&doi=10.1007%2fs00382-016-3471-2&partnerID=40&md5=71d07f782cc0511e1103984bc553e262","The objective of the present work is to compare the projections of surface solar radiation (SSR) simulated by four regional climate models (CCLM, RCA4, WRF, ALADIN) with the respective fields of their ten driving CMIP5 global climate models. First the annual and seasonal SSR changes are examined in the regional and in the global climate models based on the RCP8.5 emission scenarios. The results show significant discrepancies between the projected SSR, the multi-model mean of RCMs indicates a decrease in SSR of −0.60 W/m2 per decade over Europe, while the multi-model mean of the associated GCMs used to drive the RCMs gives an increase in SSR of +0.39 W/m2 per decade for the period of 2006–2100 over Europe. At seasonal scale the largest differences appear in spring and summer. The different signs of SSR projected changes can be interpreted as the consequence of the different behavior of cloud cover in global and regional climate models. Cloudiness shows a significant decline in GCMs with −0.24% per decade which explains the extra income in SSR, while in case of the regional models no significant changes in cloudiness can be detected. The reduction of SSR in RCMs can be attributed to increasing atmospheric absorption in line with the increase of water vapor content. Both global and regional models overestimate SSR in absolute terms as compared to surface observations, in line with an underestimation of cloud cover. Regional models further have difficulties to adequately reproduce the observed trends in SSR over the past decades. © 2016, Springer-Verlag Berlin Heidelberg."
"57192432884;6602775821;7409175472;7003814396;7004885872;","Estimating collision–coalescence rates from in situ observations of marine stratocumulus",2017,"10.1002/qj.3124","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034657278&doi=10.1002%2fqj.3124&partnerID=40&md5=1fc6d314f5d337b5fdaf961312df285e","Precipitation forms in warm clouds via collision–coalescence. This process is difficult to observe directly in situ and its implementation in numerical models is uncertain. We use aircraft observations of the drop-size distribution (DSD) near marine stratocumulus tops to estimate collision–coalescence rates. Marine stratocumulus is a useful system to study collisional growth because it is initiated near the cloud top and the clouds evolve slowly enough to obtain statistically useful data from aircraft. We compare rate constants estimated from observations with reference rate constants derived from a collision–coalescence box model, the result of which is termed the enhancement factor (EF). We evaluate two hydrodynamic collision–coalescence kernels, one quiescent and one including the effects of small-scale turbulence. Due to sampling volume limitations, DSDs must be averaged over length-scales much greater than those relevant to the underlying physics, such that we also examine the role of averaging length-scale with respect to process representation. Averaging length-scales of 1.5 and 30 km are used, corresponding roughly to the horizontal grid lengths of cloud-resolving models and high-resolution climate models, respectively. EF values range from 0.1 to 40, with the greatest EFs associated with small mode diameter cases and a generally decreasing trend with drop size. For any given drop size or averaging length-scale, there is about an order of magnitude variability in EFs. These results suggest that spatial variability on length-scales smaller than 1.5 km prevents accurate retrieval of rate constants from large-scale average DSDs. Large-scale models must therefore account for small-scale variability to represent cloud microphysical processes accurately. The turbulent kernel reduces EFs for all drop sizes, but can only account for at most half of the calculated EFs in marine stratocumulus. © 2017 Royal Meteorological Society"
"8067118800;7202899330;6701752471;","Significance of aerosol radiative effect in energy balance control on global precipitation change",2017,"10.1002/asl.780","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031754550&doi=10.1002%2fasl.780&partnerID=40&md5=83f6a5ec14076631af25c90e566f2650","Historical changes of global precipitation in the 20th century simulated by a climate model are investigated. The results simulated with alternate configurations of cloud microphysics are analyzed in the context of energy balance controls on global precipitation, where the latent heat changes associated with the precipitation change is nearly balanced with changes to atmospheric radiative cooling. The atmospheric radiative cooling is dominated by its clear-sky component, which is found to correlate with changes to both column water vapor and aerosol optical depth (AOD). The water vapor-dependent component of the clear-sky radiative cooling is then found to scale with global temperature change through the Clausius–Clapeyron relationship. This component results in a tendency of global precipitation increase with increasing temperature at a rate of approximately 2%K−1. Another component of the clear-sky radiative cooling, which is well correlated with changes to AOD, is also found to vary in magnitude among different scenarios with alternate configurations of cloud microphysics that controls the precipitation efficiency, a major factor influencing the aerosol scavenging process that can lead to different aerosol loadings. These results propose how different characteristics of cloud microphysics can cause different aerosol loadings that in turn perturb global energy balance to significantly change global precipitation. This implies a possible coupling of aerosol–cloud interaction with aerosol–radiation interaction in the context of global energy balance. © 2017 The Authors. Atmospheric Science Letters published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"57209589566;8877858700;6701754792;","Understanding the ACCESS model errors over the Maritime Continent using CloudSat and CALIPSO simulators",2017,"10.1002/qj.3168","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034241046&doi=10.1002%2fqj.3168&partnerID=40&md5=4aebde9c28fc668aa3beab5940550f81","Precipitation and cloud properties from the Australian Community Climate and Earth System Simulator (ACCESS1.3) atmospheric model are evaluated over the Maritime Continent during the monsoon season using satellite observations. The model rainfall errors in December–February are characterized by a wet bias east of 120°E and a dry bias west of that longitude. A closer look at the complex land–sea composition of the Maritime Continent reveals that ACCESS1.3 overestimates rainfall over the islands and underestimates it in the surrounding waters. These rainfall biases are associated with a distinct low-level convergence bias over land, a divergence bias over ocean, and a high-level cloud fraction overestimate over land and ocean. The complementary information offered by CloudSat and CALIPSO evaluations further shows that the model overestimates high- and low-level cloudiness and light rain and drizzle but underestimates the occurrence of mid-level clouds. Sensitivity tests are carried out to study the model response to physics parametrizations to understand these model errors. In particular, modifications to the existing parametrization such as changes to the convection scheme, to the rainfall characteristics or to the circulation, appear to qualitatively help reduce model errors. These results show that rainfall and high-level cloud fraction can be improved, but the model still suffers from a lack of occurrence of hydrometeors in the mid-levels in all sensitivity tests. Increasing cloudiness and moisture in the low- and mid-levels may be crucial to generating deeper convection and higher ice water content in the model. © 2017 Royal Meteorological Society"
"57195598354;26023642600;","Identifying sky conditions in Iran from MODIS Terra and Aqua cloud products",2017,"10.1007/s11769-017-0908-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029116819&doi=10.1007%2fs11769-017-0908-4&partnerID=40&md5=93d2627d6d9de1f414c658bcc4713106","Clouds can influence climate through many complex interactions within the hydrological cycle. Due to the important effects of cloud cover on climate, it is essential to study its variability over certain geographical areas. This study provides a spatial and temporal distribution of sky conditions, cloudy, partly cloudy, and clear days, in Iran. Cloud fraction parameters were calculated based on the cloud product (collection 6_L2) obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on board the Terra (MOD06) and Aqua (MYD06) satellites. The cloud products were collected daily from January 1, 2003 to December 31, 2014 (12 years) with a spatial resolution of 5 km × 5 km. First, the cloud fraction data were converted into a regular geographic coordinate network over Iran. Then, the estimations from both sensors were analyzed. Results revealed that the maximum annual frequency of cloudy days occurs along the southern shores of the Caspian Sea, while the minimum annual frequency occurs in southeast Iran. On average, the annual number of cloudy and clear-sky days was 88 and 256 d from MODIS Terra, as compared to 96 and 244 d from MODIS Aqua. Generally, cloudy and partly cloudy days decrease from north to south, and MODIS Aqua overestimates the cloudy and partly cloudy days compared to MODIS Terra. © 2017, Science Press, Northeast Institute of Geography and Agricultural Ecology, CAS and Springer-Verlag GmbH Germany."
"7501757094;56892889800;57195398231;","Modeling aerosol climate effects over monsoon Asia: A collaborative research program",2017,"10.1007/s00376-017-6319-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027721434&doi=10.1007%2fs00376-017-6319-8&partnerID=40&md5=b97fc81d79e56b48c232dd89ff456f4d","This paper describes the latest progress of a collaborative research program entitled “Modeling Aerosol Climate Effects over Monsoon Asia”, under the Climate Sciences agreement between the U.S. Department of Energy and the Chinese Academy of Sciences (in the early 1980s, Professor Duzheng YE played a critical role in leading and formalizing the agreement). Here, the rationale and approach for pursuing the program, the participants, and research activities of recent years are first described, and then the highlights of the program’s key findings and relevant scientific issues, as well as follow-up studies, are presented and discussed. © 2017, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag GmbH Germany."
"36699557700;41461547100;6603744207;","Comparison of meteorological conditions in Svalbard fjords: Hornsund and Kongsfjorden",2017,"10.1016/j.oceano.2017.06.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85025064986&doi=10.1016%2fj.oceano.2017.06.004&partnerID=40&md5=e5e123eb3dd15b010b199caf03ac3e8a","This paper presents the results of a comparison of basic meteorological parameters in two Arctic fjords situated on the west coast of Spitsbergen, the main island of the Svalbard archipelago. Air temperature, wind speed and direction, humidity and cloud cover from the period 2005 to 2016 are described and compared with previous (from 1975) analyses of meteorological conditions in the investigated region. Such a choice of dates coincides with the time the GAME project measurements were carried out. The main goal of this study was to compare meteorological conditions in two fjords: Hornsund and Kongsfjorden, during the time of rapid climate changes. The results are collated with research results available in literature from previous years. We discovered that in the investigated period the climate of the Hornsund region is more oceanic than in Kongsfjorden. The stable level of the difference in climate elements is manifested and is evident mainly through greater amplitudes in air temperatures in Kongsfjorden, and in stronger winds in Hornsund. © 2017 Institute of Oceanology of the Polish Academy of Sciences"
"55995777500;57205864292;57189241924;49664585700;28168059300;","Spatial and Temporal Variation Analysis of Snow Cover Using MODIS over Qinghai-Tibetan Plateau during 2003–2014",2017,"10.1007/s12524-016-0617-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983472812&doi=10.1007%2fs12524-016-0617-y&partnerID=40&md5=058647ebba11407c1d9d5d05de6cebeb","The Qinghai-Tibetan Plateau (QTP) snow cover information acquisition of the high precision spatial and temporal characteristics is of great significance for the research on its land surface atmosphere coupled system and global climate change effects. The Moderate Resolution Imaging Spectro-radiometer (MODIS) daily snow cover products (MOD10A1 and MYD10A1) have been widely used in long time series of spatial and temporal variation analysis, but they are limited to be used because of high cloud cover ratio. In this paper, a 7-day rolling combination algorithm was presented to eliminate cloud obscuration, and the whole cloud amount falls below 7 %. The ground station in situ measurements verify that the overall precision is more than 90 %. The presented algorithm guaranteed the same spatial resolution and temporal resolution, and has higher precision than products MOD10A1 and MYD10A1. The MODIS 7-day rolling combination snow cover datasets products were obtained between 2003 and 2014 in the QTP, and the snow cover area of spatial and temporal variation was analyzed. The change characteristics of snow cover duration was also studied combining with the Digital Elevation Model data. Results show that the snow cover area of the whole QTP has a slowly decreased trend, but increases in autumn. Thus, the snow cover proportion of annual periodic and unstable in different elevations has the highest correlation with area of the elevation. © 2016, Indian Society of Remote Sensing."
"56798197900;6603058114;","WorldClim 2: new 1-km spatial resolution climate surfaces for global land areas",2017,"10.1002/joc.5086","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019264593&doi=10.1002%2fjoc.5086&partnerID=40&md5=2c4e476b2699e9cc6e0c2c1abec2536e","We created a new dataset of spatially interpolated monthly climate data for global land areas at a very high spatial resolution (approximately 1 km2). We included monthly temperature (minimum, maximum and average), precipitation, solar radiation, vapour pressure and wind speed, aggregated across a target temporal range of 1970–2000, using data from between 9000 and 60 000 weather stations. Weather station data were interpolated using thin-plate splines with covariates including elevation, distance to the coast and three satellite-derived covariates: maximum and minimum land surface temperature as well as cloud cover, obtained with the MODIS satellite platform. Interpolation was done for 23 regions of varying size depending on station density. Satellite data improved prediction accuracy for temperature variables 5–15% (0.07–0.17 °C), particularly for areas with a low station density, although prediction error remained high in such regions for all climate variables. Contributions of satellite covariates were mostly negligible for the other variables, although their importance varied by region. In contrast to the common approach to use a single model formulation for the entire world, we constructed the final product by selecting the best performing model for each region and variable. Global cross-validation correlations were ≥ 0.99 for temperature and humidity, 0.86 for precipitation and 0.76 for wind speed. The fact that most of our climate surface estimates were only marginally improved by use of satellite covariates highlights the importance having a dense, high-quality network of climate station data. © 2017 Royal Meteorological Society"
"55633745800;57196349263;57195622217;57196329166;57196347601;","Examining the climatology of shortwave radiation in the northeastern United States",2017,"10.1175/JAMC-D-16-0420.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032666020&doi=10.1175%2fJAMC-D-16-0420.1&partnerID=40&md5=4ef527bb4a93af12fac891a7873be715","As demand for renewable energy grows, so does the need for an improved understanding of renewable energy sources. Paradoxically, the climate change mitigation strategy of fossil fuel divestment is in itself subject to shifts in weather patterns resulting from climate change. This is particularly true with solar power, which depends on local cloud cover. However, because observed shortwave radiation data usually span a decade or less, persistent long-term trends may not be identified. A simple linear regression model is created here using diurnal temperature range (DTR) during 2002-15 as a predictor variable to estimate long-term shortwave radiation (SR) values in the northeastern United States. Using an extended DTR dataset, SR values are computed for 1956-2015. Statistically significant decreases in shortwave radiation are identified that are dominated by changes during the summer months. Because this coincides with the season of greatest insolation and the highest potential for energy production, financial implications may be large for the solar energy industry if such trends persist into the future. © 2017 American Meteorological Society."
"57193922872;55644317800;26429409700;35933658500;55768476100;12141267000;","Spatiotemporal Reconstruction of Land Surface Temperature Derived from FengYun Geostationary Satellite Data",2017,"10.1109/JSTARS.2017.2716376","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85023157626&doi=10.1109%2fJSTARS.2017.2716376&partnerID=40&md5=626172f4aa2769845c48e8f80e5b5c02","The FengYun-2F (FY-2F) geostationary satellite land surface temperature (LST) and its diurnal variation are important when evaluating climate change, the land-Atmosphere energy budget, and the hydrological cycle. However, the presence of clouds generates numerous meaningless pixels that constrain the potential application of the available satellite LST products. These pixels covered by cloud are assigned-2, and otherwise are the LST values, based on the result of a double-channel threshold cloud detection algorithm. This paper proposes a combined temporal and spatial information reconstruction method for the missing FY-2F LST data reconstruction with a good spatial continuity, where cloud detection has already been undertaken. Compared with the methods used in the past, the main characteristics of the proposed method are: 1) the consideration of a free parameter δ T when modeling the diurnal temperature cycle curve; 2) the introduction of the genetic algorithm for solving the parameters; 3) the adoption of the spectral multimanifold clustering algorithm for clustering the multitemporal geostationary satellite LST data; and 4) the accurate and efficient combined temporal and spatial reconstruction method. The proposed combined temporal and spatial reconstruction method was tested and quantitatively assessed with both simulated and real data experiments, using the FY-2F LST products. The results indicate that the combined reconstruction method is accurate to within about 2 °C, which can significantly improve the practical value of FY-2F LST datasets. © 2008-2012 IEEE."
"57192560037;6701895637;","Do convection-permitting models improve the representation of the impact of LUC?",2017,"10.1007/s00382-016-3489-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006832857&doi=10.1007%2fs00382-016-3489-5&partnerID=40&md5=155bddc3f370fa9e2424c6b3c2cfc14f","In this study we assess the added value of convection permitting scale (CPS) simulations in studies using regional climate models to quantify the bio-geophysical climate impact of land-use change (LUC). To accomplish this, a comprehensive model evaluation methodology is applied to both non-CPS and CPS simulations. The main characteristics of the evaluation methodology are (1) the use of paired eddy-covariance site observations (forest vs open land) and (2) a simultaneous evaluation of all surface energy budget components. Results show that although generally satisfactory, non-CPS simulations fall short of completely reproducing the observed LUC signal because of three key biases. CPS scale simulations succeed at significantly reducing two of these biases, namely, those in daytime shortwave radiation and daytime sensible heat flux. Also, CPS slightly reduces a third bias in nighttime incoming longwave radiation. The daytime improvements can be attributed partially to the switch from parameterized to explicit convection, the associated improvement in the simulation of afternoon convective clouds, and resulting surface energy budget and atmospheric feedbacks. Also responsible for the improvements during daytime is a better representation of surface heterogeneity and thus, surface roughness. Meanwhile, the modest nighttime longwave improvement can be attributed to increased vertical atmospheric resolution. However, the model still fails at reproducing the magnitude of the observed nighttime longwave difference. One possible explanation for this persistent bias is the nighttime radiative effect of biogenic volatile organic compound emissions over the forest site. A correlation between estimated emission rates and the observed nighttime longwave difference, as well as the persistence of the longwave bias provide support for this hypothesis. However, more research is needed to conclusively determine if the effect indeed exists. © 2016, Springer-Verlag Berlin Heidelberg."
"57193385740;7401796996;56768785200;8629713500;56182620500;55831774800;","Quantifying the uncertainties of reanalyzed Arctic cloud and radiation properties using satellite surface observations",2017,"10.1175/JCLI-D-16-0722.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028975819&doi=10.1175%2fJCLI-D-16-0722.1&partnerID=40&md5=0ae04bc7ad280bc24045716a23d13cef","Reanalyses have proven to be convenient tools for studying the Arctic climate system, but their uncertainties should first be identified. In this study, five reanalyses (JRA-55, 20CRv2c, CFSR, ERA-Interim, and MERRA-2) are compared with NASA CERES-MODIS (CM)-derived cloud fractions (CFs), cloud water paths (CWPs), topof- atmosphere (TOA) and surface longwave (LW) and shortwave (SW) radiative fluxes over theArctic (708-908N) over the period of 2000-12, and CloudSat-CALIPSO (CC)-derived CFs from2006 to 2010. Themonthlymean CFs in all reanalyses except JRA-55 are close to or slightly higher than the CC-derived CFs from May to September. However, wintertime CF cannot be confidently evaluated until instrument simulators are implemented in reanalysis products. The comparison betweenCMandCCCFs indicates thatCM-derived CFs are reliable in summer but not in winter. Although the reanalysisCWPs follow the general seasonal variations ofCMCWPs, their annual means are only half or even less than the CM-retrieved CWPs (126 gm-2). The annual mean differences in TOA and surface SW and LWfluxes between CERES EBAF and reanalyses are less than 6Wm-2 for TOA radiative fluxes and 16Wm-2 for surface radiative fluxes. All reanalyses show positive biases along the northern and eastern coasts of Greenland as a result of model elevation biases or possible CMclear-sky retrieval issues. The correlations between the reanalyses and CERES satellite retrievals indicate that all five reanalyses estimate radiative fluxes better than cloud properties, and MERRA-2 and JRA-55 exhibit comparatively higher correlations for Arctic cloud and radiation properties. © 2017 American Meteorological Society."
"6603716786;","Svalbard as a study model of future High Arctic coastal environments in a warming world",2017,"10.1016/j.oceano.2017.06.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85025460728&doi=10.1016%2fj.oceano.2017.06.005&partnerID=40&md5=71fb771c72a9a317838636871c14eeaf","Svalbard archipelago, a high latitude area in a region undergoing rapid climate change, is relatively easily accessible for field research. This makes the fjords of Spitsbergen, its largest island, some of the best studied Arctic coastal areas. This paper aims at answering the question of how climatically diverse the fjords are, and how representative they are for the expected future Arctic diminishing range of seasonal sea-ice. This study uses a meteorological reanalysis, sea surface temperature climatology, and the results of a recent one-year meteorological campaign in Spitsbergen to determine the seasonal differences between different Spitsbergen fjords, as well as the sea water temperature and ice ranges around Svalbard in recent years. The results show that Spitsbergen fjords have diverse seasonal patterns of air temperature due to differences in the SST of the adjacent ocean, and different cloudiness. The sea water temperatures and ice concentrations around Svalbard in recent years are similar to what is expected most of the Arctic coastal areas in the second half of this century. This makes Spitsbergen a unique field study model of the conditions expected in future warmer High Arctic. © 2017 Institute of Oceanology of the Polish Academy of Sciences"
"22235457800;7403531523;52264136000;7004364155;","Determination of CERES TOA fluxes using machine learning algorithms. Part I: Classification and retrieval of CERES cloudy and clear scenes",2017,"10.1175/JTECH-D-16-0183.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032746166&doi=10.1175%2fJTECH-D-16-0183.1&partnerID=40&md5=ecf69b5675c0551235ccb0203aca6fc7","Continuous monitoring of the earth radiation budget (ERB) is critical to the understanding of Earth's climate and its variability with time. The Clouds and the Earth's Radiant Energy System (CERES) instrument is able to provide a long record of ERB for such scientific studies. This manuscript, which is the first of a two-part paper, describes the new CERES algorithm for improving the clear/cloudy scene classification without the use of coincident cloud imager data. This new CERES algorithm is based on a subset of the modern artificial intelligence (AI) paradigm called machine learning (ML) algorithms. This paper describes the development and application of the ML algorithm known as random forests (RF), which is used to classify CERES broadband footprint measurements into clear and cloudy scenes. Results from the RF analysis carried using the CERES Single Scanner Footprint (SSF) data for January and July are presented in the manuscript. The daytime RF misclassification rate (MCR) shows relatively large values (> 30%) for snow, sea ice, and bright desert surface types, while lower values (< 10%) for the forest surface type. MCR values observed for the nighttime data in general show relatively larger values for most of the surface types compared to the daytime MCR values. The modified MCR values show lower values (< 4%) for most surface types after thin cloud data are excluded from the analysis. Sensitivity analysis shows that the number of input variables and decision trees used in the RF analysis has a substantial influence on determining the classification error. © 2017 American Meteorological Society."
"56341989200;7006399667;6701511321;7403263977;","Using the artificial tracer e90 to examine present and future UTLS tracer transport in WACCM",2017,"10.1175/JAS-D-17-0135.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031089334&doi=10.1175%2fJAS-D-17-0135.1&partnerID=40&md5=6a30de3bd80c41394ff51e1e0a6494fe","Large-scale tracer transport in the upper troposphere and lower stratosphere (UTLS) is investigated using simulations of the Whole Atmosphere Community Climate Model (WACCM) over the period 1955-2099. The analyses are based on e90, an artificial passive tracer with constant emissions and atmospheric loss rates. The separate contributions of advection by the residual circulation, eddy mixing, and subgrid convection to total transport are explicitly evaluated. The results highlight distinct largescale transport regimes in the tropics, characterized by efficient vertical tracer transport, and the extratropics, dominated by isentropic mixing. One novel result is the important role of vertical eddy mixing in the tropical upper troposphere. It is shown that interannual variability in e90 is largely driven by El Niño-Southern Oscillation and the quasi-biennial oscillation. The long-term trends emphasize a strong impact of a rising tropopause with climate change on UTLS dynamics and tracer transport. The analyses directly attribute the e90 trends to changes in the different transport components. Stronger residual circulation in the future leads to increased tracer concentrations in the tropical lower stratosphere. Enhanced eddy mixing increases e90 in the extratropical lowermost stratosphere, linked to an upward shift of wave dissipation tied to the tropopause rise. In the troposphere, reduced concentrations in the future are due to weaker convective transport out of the boundary layer and weaker extratropical isentropic eddy mixing. © 2017AmericanMeteorological Society."
"56001772500;57196405106;55882114500;57192625282;57188830149;49663488000;","Spatiotemporal variation of snow cover in Tianshan Mountains, Central Asia, based on cloud-free MODIS fractional snow cover product, 2001-2015",2017,"10.3390/rs9101045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032874423&doi=10.3390%2frs9101045&partnerID=40&md5=575696f64a18853c94ef1ce960e9a0d6","The change in snow cover under climate change is poorly understood in Tianshan Mountains. Here, we investigate the spatiotemporal characteristics and trends of snow-covered area (SCA) and snow-covered days (SCD) in the Tianshan Mountains by using the cloud-removed MODIS fractional snow cover datasets from 2001-2015. The possible linkage between the snow cover and temperature and precipitation changes over the Tianshan Mountains is also investigated. The results are as follows: (1) The distribution of snow cover over the Tianshan Mountains exhibits a large spatiotemporal heterogeneity. The areas with SCD greater than 120 days are distributed in the principal mountains with elevations of above 3000 m. (2) In total, 26.39% (5.09% with a significant decline) and 34.26% (2.81% with a significant increase) of the study area show declining and increasing trend in SCD, respectively. The SCD mainly decreases in Central and Eastern Tianshan (decreased by 11.88% and 8.03%, respectively), while it increases in Northern and Western Tianshan (increased by 9.36% and 7.47%). (3) The snow cover variations are linked to the temperature and precipitation changes. Temperature tends to be the major factor effecting the snow cover changes in the Tianshan Mountains during 2001-2015. © 2017 by the authors."
"42962694100;55190636600;55516935400;55355215900;56608842400;55142073200;","Impacts of cloud cover on long-term changes in light rain in Eastern China",2017,"10.1002/joc.5095","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018987239&doi=10.1002%2fjoc.5095&partnerID=40&md5=464e97d270445ee86d5b67d547c3f47a","Daily sunshine duration data from 384 stations in Eastern China was used to separate light rain in the warm season during the period 1979–2009 into light rain occurred in overcast and partly cloudy weather. Light rain reduction over past 30 years mainly happened in partly cloudy weather, which accounted for 84% of the decrease of total light rain days and amount in the warm seasons over Eastern China during the period 1979–2009. The primary cause of the significant reduction of light rain in partly cloudy weather was the relative humidity decrease in the low troposphere, which was induced by both the air temperature increase and water vapour content (WVC) decrease, while warming played a much more important role compared with the WVC in the change of light rain in most regions of Eastern China. © 2017 Royal Meteorological Society"
"55574825700;57201570597;7102092302;55976888100;7003902659;","The Effects of Heat Advection on UK Weather and Climate Observations in the Vicinity of Small Urbanized Areas",2017,"10.1007/s10546-017-0263-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020710107&doi=10.1007%2fs10546-017-0263-0&partnerID=40&md5=b6d52884d89c47cdac83fc7d5693c3ba","Weather and climate networks traditionally follow rigorous siting guidelines, with individual stations located away from frost hollows, trees or urban areas. However, the diverse nature of the UK landscape suggests that the feasibility of siting stations that are truly representative of regional climate and free from distorting local effects is increasingly difficult. Whilst the urban heat island is a well-studied phenomenon and usually accounted for, the effect of warm urban air advected downwind is rarely considered, particularly at rural stations adjacent to urban areas. Until recently, urban heat advection (UHA) was viewed as an urban boundary-layer process through the formation of an urban plume that rises above the surface as it is advected. However, these dynamic UHA effects are shown to also have an impact on surface observations. Results show a significant difference in temperatures anomalies (p<0.001) between observations taken downwind of urban and rural areas. For example, urban heat advection from small urbanized areas (∼ 1km2) under low cloud cover and wind speeds of 2–3ms-1 is found to increase mean nocturnal air temperatures by 0.6∘C at a horizontal distance of 0.5 km. Fundamentally, these UHA results highlight the importance of careful interpretation of long-term temperature data taken near small urban areas. © 2017, The Author(s)."
"55457938900;57208041580;6603476391;","Local and regional climatic signals recorded in tree-rings of Chukrasia tabularis in Bangladesh",2017,"10.1016/j.dendro.2017.06.006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022022709&doi=10.1016%2fj.dendro.2017.06.006&partnerID=40&md5=859d05fe1bcea459734a04978d166ede","We developed the first tree-ring chronology of Chukrasia tabularis from a moist tropical forest in Bangladesh, spanning the 102-year period 1911–2012. The species showed wood anatomically clear annual tree-ring boundaries which crossdated between tree individuals. Bootstrapped correlation analyses revealed that the ring-width index was significantly negatively correlated with current year mean and minimum temperatures. This relationship was stronger during the dry season (November–March), the pre-monsoon (February–April) and the post-monsoon season (September–November) than during the main monsoon season (May–August). We interpret this result as an indication that temperature-driven higher evapotranspiration outside the main rainy season leads to water stress limiting tree growth. This is confirmed by negative correlations of the ring-width index with the Palmer Drought Severity Index (PDSI) during the dry season. Precipitation did not show significant relationships to tree growth, except in current year June. However, cloud cover strongly negatively affected tree growth, likely by reducing photosynthetic capacity particularly during the rainy summer (May–August) monsoon season. On a regional scale, the ring-width index was correlated with both Indian Ocean and Pacific Ocean sea surface temperature (SST) anomalies, but during different seasons. Ring width of C. tabularis was also significantly correlated with the El Niño Southern Oscillation (ENSO). Monthly Niño 3.4 region positive temperature anomalies enhanced current year tree growth but negative temperature anomalies reduced tree growth in the following year mainly through modulating local climate. Hence, tree-ring variations of C. tabularis in Bangladesh record local and regional climate signals and are a potential proxy to reconstruct local and regional paleoclimatic variability during the past centuries. © 2017 Elsevier GmbH"
"54917441600;57195639183;57195641176;57195635531;","Low dimensional embedding of climate data for radio astronomical site testing in the Colombian Andes",2017,"10.1088/1538-3873/aa83fe","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029405247&doi=10.1088%2f1538-3873%2faa83fe&partnerID=40&md5=ba5678f47b711e78fb51a44a8aebe4f4","We set out to evaluate the potential of the Colombian Andes for millimeter-wave astronomical observations. Previous studies for astronomical site testing in this region have suggested that nighttime humidity and cloud cover conditions make most sites unsuitable for professional visible-light observations. Millimeter observations can be done during the day, but require that the precipitable water vapor column above a site stays below ~10 mm. Due to a lack of direct radiometric or radiosonde measurements, we present a method for correlating climate data from weather stations to sites with a low precipitable water vapor column. We use unsupervised learning techniques to low dimensionally embed climate data (precipitation, rain days, relative humidity, and sunshine duration) in order to group together stations with similar long-term climate behavior. The data were taken over a period of 30 years by 2046 weather stations across the Colombian territory. We find six regions with unusually dry, clear-sky conditions, ranging in elevations from 2200 to 3800 masl. We evaluate the suitability of each region using a quality index derived from a Bayesian probabilistic analysis of the station type and elevation distributions. Two of these regions show a high probability of having an exceptionally low precipitable water vapor column. We compared our results with global precipitable water vapor maps and find a plausible geographical correlation with regions with low water vapor columns (~10 mm) at an accuracy of ~20 km. Our methods can be applied to similar data sets taken in other countries as a first step toward astronomical site evaluation. © 2017. The Astronomical Society of the Pacific. All rights reserved. Printed in the U.S.A."
"57194110395;12752927300;7102196528;","Future climate change of stability indices for the Iberian Peninsula",2017,"10.1002/joc.5094","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018792827&doi=10.1002%2fjoc.5094&partnerID=40&md5=e8c525a82088576fdcdee6f086cd288f","Stability indices evaluate the atmospheric instability which is a basic and precursor ingredient needed for storms to develop. In this study, we evaluated changes of some atmospheric stability indices, namely Convective Available Potential Energy (CAPE), Deep-Layer Wind Shear (SHR06) and Severe Weather Threat (SWEAT), for the Iberian Peninsula, for a future climate scenario (2081–2100), considering the greenhouse gases emission scenario RCP8.5, relative to a historical period (1986–2005). The Weather Research and Forecasting (WRF) was forced by ERA-Interim, for validation purposes, and by the Max Planck Institute (MPI) Earth System Model. The novelty of this approach is the study of extreme weather events through the evaluation of conditions favourable to their development instead of directly studying them. The latter approach may be problematic since these phenomena are known to be poorly reproduced by models due to their relatively low resolution and parametrization processes such as clouds and precipitation. Our approach uses stability indices obtained from simulated variables, such as temperature and winds, which are, generally, much better simulated by models. The WRF-MPI model was validated against WRF-ERA. Overall, the WRF-MPI simulates well the three indices considered here, particularly CAPE, when compared to WRF-ERA. Their spatial patterns were similar, although there is a systematic positive bias in the WRF-MPI. This is minimized when we evaluate climate change by computing differences of WRF-MPI simulations between the future climate scenario and the historical period. In the future, it is estimated a significant increase of CAPE and SWEAT intensity, mainly in summer and autumn. It is also expected a decrease of SHR06 intensity in summer and autumn and an increase in the remaining seasons. Therefore, we may anticipate an increase of the probability of occurrence of environments favourable to the development of severe weather, mainly in the Mediterranean, mostly associated to higher CAPE values. © 2017 Royal Meteorological Society"
"55533168400;8568836700;","Influences of the seasonal growth of vegetation on surface energy budgets over middle to high latitudes",2017,"10.1002/joc.5068","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016631428&doi=10.1002%2fjoc.5068&partnerID=40&md5=74d24526b33031158afdf92e1e5ef9d9","The feedbacks of vegetation growth to climate are very important and exhibit large differences, depending on seasons and characteristics of plants and climate. Through two simulations, this work investigated these differences among the influences of the seasonal growth of different vegetation on surface energy budgets over the latitudinal range of 30–90°N and detected associated causes. The seasonal growth of vegetation is expressed as an increase in leaf area index (LAI) during the growing season (April–October) compared to boreal winter (December–January–February). The results showed that notable effects occurred in latent heat flux, downward solar radiation and reflected solar radiation for dominant plant functional types (PFTs). With a seasonal increase in LAI, the latent heat flux of ‘needleleaf evergreen boreal tree’ (NEB) decreased, while it increased for the other dominant PFTs. Such unexpected behaviours of NEB were mainly contributed by the weak changes in its transpiration, which was associated to land-atmosphere feedbacks (the decreased downward solar radiation) and competitions among PFTs (the intensified transpirations of the deciduous vegetation PFTs). Surface downward solar radiation decreased for all dominant vegetation PFTs because of more low clouds. The reflected solar radiation of ‘broadleaf deciduous temperate tree’ increased along with increased LAI because its leaf albedo is higher than that of the background soil, and the reflected solar radiation of ‘broadleaf deciduous boreal shrub’ drastically decreased during April and May, which resulted from its interactions with accumulated snow. This paper sufficiently proves that the feedbacks of different vegetation to surface energy balance could vary widely, not only in magnitudes but also in directions. Therefore, it is very important to accurately parameterize vegetation phenology and optical properties for a better representation of vegetation–climate interactions. © 2017 Royal Meteorological Society"
"35362702300;57206511020;15319530000;","Characterization of convective systems and their association with African easterly waves",2017,"10.1002/joc.5085","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018314225&doi=10.1002%2fjoc.5085&partnerID=40&md5=181215c37799cc8a1c8330c9ebe52de7","This study investigates the relationship between African easterly waves (AEWs) and different types of deep convection. It is known that AEWs impact the development of deep convection over tropical North Africa and tropical cyclone formation over the eastern Atlantic. However, the process of how AEWs interact with deep convection is not well understood. Composite analysis based on a 24-year data set of cloud systems (CS) from the International Satellite Cloud Climate Project shows that the relationship changes with various types of convection over this region. This phase change relationship analysis may shed light into the dynamics of AEWs and improve the ability of forecasters to anticipate associated rainfall over the Sahel. Weak and disorganized convective systems (WDCSs; 50 km < radius < 100 km) are most common within the southerly phase of the AEWs over East Africa. Mesoscale convective systems (MCSs) with cloud radii >100 km increase in frequency within and to the west of the AEW-trough zone. MCSs are common features of summer in northwestern Africa. Our results indicate that the association between AEWs and deep convection is different and changes across North Africa. Weak AEWs over East Africa have a stronger relationship with WDCSs, while mature AEWs over West Africa have more MCS activity. This evolution suggests that the organization of convection from WDCS to MCS may play a critical role in AEW development. This hypothesis contrasts the traditional view that treats convection uniformly. © 2017 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"56768490800;7006399667;57206204012;","Relationships between outgoing longwave radiation and diabatic heating in reanalyses",2017,"10.1007/s00382-016-3501-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007505785&doi=10.1007%2fs00382-016-3501-0&partnerID=40&md5=fc5f229eff9f5126d82441451bf9fa00","This study investigates relationships between daily variability in National Oceanographic and Atmospheric Administration (NOAA) outgoing longwave radiation (OLR), as a proxy for deep convection, and the global diabatic heat budget derived from reanalysis data sets. Results are evaluated based on data from ECMWF Reanalysis (ERA-Interim), Japanese 55-year Reanalysis (JRA-55) and Modern-Era Retrospective Analysis for Research and Applications (MERRA2). The diabatic heating is separated into components linked to ‘physics’ (mainly latent heat fluxes), plus longwave (LW) and shortwave (SW) radiative tendencies. Transient variability in deep convection is highly correlated with diabatic heating throughout the troposphere and stratosphere. Correlation patterns and composite analyses show that enhanced deep convection (lower OLR) is linked to amplified heating in the tropical troposphere and in the mid-latitude storm tracks, tied to latent heat release. Enhanced convection is also linked to radiative cooling in the lower stratosphere, due to weaker upwelling LW from lower altitudes. Enhanced transient deep convection increases LW and decreases SW radiation in the lower troposphere, with opposite effects in the mid to upper troposphere. The compensating effects in LW and SW radiation are largely linked to variations in cloud fraction and water content (vapor, liquid and ice). These radiative balances in reanalyses are in agreement with idealized calculations using a column radiative transfer model. The overall relationships between OLR and diabatic heating are robust among the different reanalyses, although there are differences in radiative tendencies in the tropics due to large differences of cloud water and ice content among the reanalyses. These calculations provide a simple statistical method to quantify variations in diabatic heating linked to transient deep convection in the climate system. © 2016, Springer-Verlag Berlin Heidelberg."
"57188758598;","A Simple Mechanical Model of Soot Spherule Motion on a Soot Chain",2017,"10.1007/s41810-017-0014-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85079710815&doi=10.1007%2fs41810-017-0014-0&partnerID=40&md5=33aec2b4def6132bc7aacba3878b09a8","Soot chains, formed from freshly combusted material, are composed of individual soot spherules connected together. The soot chains have complex structures on which gases have been observed to deposit on the surface. The deposition of these gases can cause the soot chains to compress from their original configuration into a shape with a smaller aerodynamic diameter and higher density. This shape rearrangement changes the soot agglomerates’ climate impacts including its radiative properties and its potential to become a cloud condensation nuclei. To better understand how quickly the soot chain might change shape, a simple mechanical model is presented of individual soot spherule motion in the presence of a surfactant. Discussion of this model, its limitations, and potential follow-on work are also given. © 2017, Institute of Earth Environment, Chinese Academy Sciences."
"6603263640;7404970050;","Reconstruction of thermodynamic cycles in a high-resolution simulation of a hurricane",2017,"10.1175/JAS-D-16-0353.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031099704&doi=10.1175%2fJAS-D-16-0353.1&partnerID=40&md5=66283407b3e184098cf960387c324b9a","The relationship between energy transport and kinetic energy generation in a hurricane is analyzed. The hydrological cycle has a negative impact on the generation of kinetic energy. First, in a precipitating atmosphere, mechanical work must also be expended in order to lift water. Second, the injection of water vapor at low relative humidity and its removal through condensation and precipitation reduces the ability of a thermodynamic cycle to generate work. This reduction can be directly quantified in terms of the change in the Gibbs free energy between the water added and removed. Anewly developed approach-namely, themean airflow as Lagrangian dynamics approximation-is used to extract thermodynamic cycles from the standard output of a numerical simulation of a hurricane. While convection in the outer rainbands is inefficient at producing kinetic energy, the deepest overturning circulation associated with the rising air within the eyewall is an efficient heat engine that produces about 70% as much kinetic energy as a comparable Carnot cycle. This confirms that thermodynamic processes play a central role in hurricane formation and intensification and that the thermodynamic cycles in a hurricane are characterized by high generation of kinetic energy that differ significantly from those found in atmospheric convection. © 2017AmericanMeteorological Society."
"55175441000;56204129800;24829796300;57196404526;57196403632;","The geometry of large tundra lakes observed in historical maps and satellite images",2017,"10.3390/rs9101072","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032865495&doi=10.3390%2frs9101072&partnerID=40&md5=433149dd9a2a43e09cd79fc65ae114f8","The climate of the Arctic is warming rapidly and this is causing major changes to the cycling of carbon and the distribution of permafrost in this region. Tundra lakes are key components of the Arctic climate system because they represent a source of methane to the atmosphere. In this paper, we aim to analyze the geometry of the patterns formed by large (&gt; 0.8 km2) tundra lakes in the Russian High Arctic. We have studied images of tundra lakes in historical maps from the State Hydrological Institute, Russia (date 1977; scale 0.21166 km/pixel) and in Landsat satellite images derived from the Google Earth Engine (G.E.E.; date 2016; scale 0.1503 km/pixel). The G.E.E. is a cloud-based platform for planetary-scale geospatial analysis on over four decades of Landsat data. We developed an image-processing algorithm to segment these maps and images, measure the area and perimeter of each lake, and compute the fractal dimension of the lakes in the images we have studied. Our results indicate that as lake size increases, their fractal dimension bifurcates. For lakes observed in historical maps, this bifurcation occurs among lakes larger than 100 km2 (fractal dimension 1.43 to 1.87). For lakes observed in satellite images this bifurcation occurs among lakes larger than ~100 km2 (fractal dimension 1.31 to 1.95). Tundra lakes with a fractal dimension close to 2 have a tendency to be self-similar with respect to their area-perimeter relationships. Area-perimeter measurements indicate that lakes with a length scale greater than 70 km2 are power-law distributed. Preliminary analysis of changes in lake size over time in paired lakes (lakes that were visually matched in both the historical map and the satellite imagery) indicate that some lakes in our study region have increased in size over time, whereas others have decreased in size over time. Lake size change during this 39-year time interval can be up to half the size of the lake as recorded in the historical map. © 2017 by the authors."
"57188381200;7006515772;8394117100;16231048600;7005420968;14825077300;7006936301;","Comparison of Elevation Change Detection Methods from ICESat Altimetry over the Greenland Ice Sheet",2017,"10.1109/TGRS.2017.2709303","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028854078&doi=10.1109%2fTGRS.2017.2709303&partnerID=40&md5=4f03d8a72984caf1c07b1cb47160108e","Estimation of the surface elevation change of the Greenland Ice Sheet (GrIS) is essential for understanding its response to recent and future climate change. Laser measurements from the NASA's Ice, Cloud, and land Elevation Satellite (ICESat) created altimetric surveys of GrIS surface elevations over the 2003-2009 operational period of the mission. This paper compares four change detection methods using Release 634 ICESat laser altimetry data: repeat tracks (RTs), crossovers (XOs), overlapping footprints (OFPs), and triangulated irregular networks (TINs). All four methods begin with a consistently edited data set and yield estimates of volumetric loss of ice from the GrIS ranging from -193 to -269 km3/yr. Using a uniform approach for quantifying uncertainties, we find that volume change rates at the drainage system scale from the four methods can be reconciled within 1-σ uncertainties in just 5 of 19 drainage systems. Ice-sheet-wide volume change estimates from the four methods cannot be reconciled within 1-σ uncertainties. Our volume change estimates lie within the range of previously published estimates, highlighting that the choice of method plays a dominant role in the scatter of volume change estimates. We find that for much of the GrIS, the OFP and TIN methods yield the lowest volume change uncertainties because of their superior spatial distribution of elevation change rate estimates. However, the RT and XO methods offer inherent advantages, and the future work to combine the elevation change detection methods to produce better estimates is warranted. © 2017 IEEE."
"6603463248;24079506900;","Ensemble versus deterministic performance at the kilometer scale",2017,"10.1175/WAF-D-16-0164.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032260101&doi=10.1175%2fWAF-D-16-0164.1&partnerID=40&md5=609277de23e8a0b21c26bea74dbb1c7c","What is the benefit of a near-convection-resolving ensemble over a near-convection-resolving deterministic forecast? In this paper, a way in which ensemble and deterministic numerical weather prediction (NWP) systems can be compared is demonstrated using a probabilistic verification framework. Three years' worth of raw forecasts from the Met Office Unified Model (UM) 12-member 2.2-km Met Office Global and Regional Ensemble Prediction System (MOGREPS-UK) ensemble and 1.5-km Met Office U.K. variable resolution (UKV) deterministic configuration were compared, utilizing a range of forecast neighborhood sizes centered on surface synoptic observing site locations. Six surface variables were evaluated: temperature, 10-m wind speed, visibility, cloud-base height, total cloud amount, and hourly precipitation. Deterministic forecasts benefit more from the application of neighborhoods, though ensemble forecast skill can also be improved. This confirms that while neighborhoods can enhance skill by sampling more of the forecast, a single deterministic model state in time cannot provide the variability, especially at the kilometer scale, where rapid error growth acts to limit local predictability. Ensembles are able to account for the uncertainty at larger, synoptic scales. The results also show that the rate of decrease in skill with lead time is greater for the deterministic UKV. MOGREPS-UK retains higher skill for longer. The concept of a skill differential is introduced to find the smallest neighborhood size at which the deterministic and ensemble scores are comparable. This was found to be 3 × 3 (6.6 km) for MOGREPS-UK and 11 × 11 (16.5 km) for UKV. Comparable scores are between 2% and 40% higher for MOGREPS-UK, depending on the variable. Naively, this would also suggest that an extra 10 km in spatial accuracy is gained by using a kilometer-scale ensemble. © 2017 American Meteorological Society."
"57196186065;7410151615;7006329926;","A study on the influences of low-frequency vorticity on tropical cyclone formation in the western North Pacific",2017,"10.1175/MWR-D-17-0085.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032200514&doi=10.1175%2fMWR-D-17-0085.1&partnerID=40&md5=088cb3488700618710c63dce58732ec6","The WRF Model is used to simulate 52 tropical cyclones (TCs) that formed in the western North Pacific during 2008-09 to study the influence of the low-frequency mode of environmental vorticity on TC formation [Vmax ~ 25 kt (~13ms-1)]. All simulations, using the same model setting, are repeated at four distinct initial times and with two different initial datasets. These TCs are classified into two groups based on the environmental 850-hPa low-frequency vorticity (using a 10-day low-pass filter) during the period 24-48 h prior to TC formation. Results show that theWRFModel is more capable of simulating the TC formation process, but with larger track errors for TCs formed in an environment with higher low-frequency vorticity (HTC). In contrast, the model is less capable of simulating the TC formation process for TCs formed in an environment with lower low-frequency vorticity (LTC), but with smaller track errors. Fourteen selected TCs are further simulated to examine the sensitivity of previous results to different cumulus parameterization schemes. Results show that the capability of theWRFModel to simulateHTCformation is not sensitive to the choice of cumulus scheme. However, for an LTC, the simulated convection pattern is very sensitive to the cumulus scheme used; therefore, model simulation capability for LTC depends on the cumulus scheme used. Results of this study reveal that the convection process is not a dominant factor in HTC formation, but is very important for LTC formation. © 2017 American Meteorological Society."
"57162805400;8688065800;","Observation Bias Correction Reveals More Rapidly Draining Lakes on the Greenland Ice Sheet",2017,"10.1002/2017JF004255","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031728534&doi=10.1002%2f2017JF004255&partnerID=40&md5=b7022f33e7b583be3d158cf02249b33c","Rapid drainage of supraglacial lakes on the Greenland Ice Sheet enables the establishment of surface-to-bed hydrologic connections and subsequent basal water delivery. Estimates of the number and spatial distribution of rapidly draining lakes vary widely, and no study has so far quantified the impact of observation bias due to cloud cover in satellite imagery on reported frequency of rapid lake drainage. To better understand the rapid drainage mechanism, we map and track an average of 515 supraglacial lakes per year in central West Greenland from 2000 to 2015. We test four previously published definitions of rapid lake drainage and find the proportion of rapidly draining lakes to vary from 3% to 38% and to be strongly dependent on observation frequency. We then apply an observation bias correction and test three new drainage criteria, which reveal a bias-corrected rapid drainage probability of 36–45%. When observation bias is addressed, we can also show that lakes above 1,600 m are as likely to drain rapidly as lakes located at lower elevations. We conclude that inconsistent detection methodologies and observation bias have obscured the true frequency of rapidly draining lakes and that the rapid lake drainage mechanism will establish surface-to-bed hydrologic connections at increasing distance from the margin as supraglacial lakes expand inland under climate warming. ©2017. American Geophysical Union. All Rights Reserved."
"15051249600;57190743768;57190534239;22236141200;57190743035;12807069100;","Impact and suggestion of column-to-surface vertical correction scheme on the relationship between satellite aod and ground-level PM2.5 in China",2017,"10.3390/rs9101038","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032863114&doi=10.3390%2frs9101038&partnerID=40&md5=2c151b77f98b520cdfcf6841c3883bc6","As China is suffering from severe fine particle pollution from dense industrialization and urbanization, satellite-derived aerosol optical depth (AOD) has been widely used for estimating particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5). However, the correlation between satellite AOD and ground-level PM2.5 could be influenced by aerosol vertical distribution, as satellite AOD represents the entire column, rather than just ground-level concentration. Here, a new column-to-surface vertical correction scheme is proposed to improve separation of the near-surface and elevated aerosol layers, based on the ratio of the integrated extinction coefficient within 200-500m above ground level (AGL), using the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP)) aerosol profile products. There are distinct differences in climate, meteorology, terrain, and aerosol transmission throughout China, so comparisons between vertical correction via CALIOP ratio and planetary boundary layer height (PBLH) were conducted in different regions from 2014 to 2015, combined with the original Pearson coefficient between satellite AOD and ground-level PM2.5 for reference. Furthermore, the best vertical correction scheme was suggested for different regions to achieve optimal correlation with PM2.5, based on the analysis and discussion of regional and seasonal characteristics of aerosol vertical distribution. According to our results and discussions, vertical correction via PBLH is recommended in northwestern China, where the PBLH varies dramatically, stretching or compressing the surface aerosol layer; vertical correction via the CALIOP ratio is recommended in northeastern China, southwestern China, Central China (excluding summer), North China Plain (excluding Beijing), and the spring in the southeast coast, areas that are susceptible to exogenous aerosols and exhibit the elevated aerosol layer; and original AOD without vertical correction is recommended in Beijing and the southeast coast (excluding spring), where the elevated aerosol layer rarely occurs and a large proportion of aerosol is aggregated in near-surface. Moreover, validation experiments in 2016 agreed well with our discussions and conclusions drawn from the experiments of the first two years. Furthermore, suggested vertical correction scheme was applied into linear mixed effect (LME) model, and high cross validation (CV) R2 (~85%) and relatively low root mean square errors (RMSE, ~20 μg/m3) were achieved, which demonstrated that the PM2.5 estimation agreed well with the measurements. When compared to the original situation, CV R2 values and RMSE after vertical correction both presented improvement to a certain extent, proving that the suggested vertical correction schemes could further improve the estimation accuracy of PM2.5 based on sophisticated model in China. Estimating PM2.5 with better accuracy could contribute to a more precise research of ecology and epidemiology, and provide a reliable reference for environmental policy making by governments. © 2017 by the authors."
"57192918313;6506606807;16550978800;57195964682;","Cirrus cloud retrieval with MSG/SEVIRI using artificial neural networks",2017,"10.5194/amt-10-3547-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030550890&doi=10.5194%2famt-10-3547-2017&partnerID=40&md5=302e5822beb1f35a9c08cf5c3f2fc55e","Cirrus clouds play an important role in climate as they tend to warm the Earth-atmosphere system. Nevertheless their physical properties remain one of the largest sources of uncertainty in atmospheric research. To better understand the physical processes of cirrus clouds and their climate impact, enhanced satellite observations are necessary. In this paper we present a new algorithm, CiPS (Cirrus Properties from SEVIRI), that detects cirrus clouds and retrieves the corresponding cloud top height, ice optical thickness and ice water path using the SEVIRI imager aboard the geostationary Meteosat Second Generation satellites. CiPS utilises a set of artificial neural networks trained with SEVIRI thermal observations, CALIOP backscatter products, the ECMWF surface temperature and auxiliary data. CiPS detects 71 and 95% of all cirrus clouds with an optical thickness of 0.1 and 1.0, respectively, that are retrieved by CALIOP. Among the cirrus-free pixels, CiPS classifies 96% correctly. With respect to CALIOP, the cloud top height retrieved by CiPS has a mean absolute percentage error of 10% or less for cirrus clouds with a top height greater than 8km. For the ice optical thickness, CiPS has a mean absolute percentage error of 50% or less for cirrus clouds with an optical thickness between 0.35 and 1.8 and of 100% or less for cirrus clouds with an optical thickness down to 0.07 with respect to the optical thickness retrieved by CALIOP. The ice water path retrieved by CiPS shows a similar performance, with mean absolute percentage errors of 100% or less for cirrus clouds with an ice water path down to 1.7 mg-2. Since the training reference data from CALIOP only include ice water path and optical thickness for comparably thin clouds, CiPS also retrieves an opacity flag, which tells us whether a retrieved cirrus is likely to be too thick for CiPS to accurately derive the ice water path and optical thickness. By retrieving CALIOP-like cirrus properties with the large spatial coverage and high temporal resolution of SEVIRI during both day and night, CiPS is a powerful tool for analysing the temporal evolution of cirrus clouds including their optical and physical properties. To demonstrate this, the life cycle of a thin cirrus cloud is analysed. © 2017 Author(s)."
"55512618700;57202301596;55311595900;56326399100;","Western Pacific emergent constraint lowers projected increase in Indian summer monsoon rainfall",2017,"10.1038/nclimate3387","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032581767&doi=10.1038%2fnclimate3387&partnerID=40&md5=6b9adeaa0ee732ffc83766fece6188bc","The agrarian-based socioeconomic livelihood of densely populated South Asian countries is vulnerable to modest changes in Indian summer monsoon (ISM) rainfall. How the ISM rainfall will evolve is a question of broad scientific and socioeconomic importance. In response to increased greenhouse gas (GHG) forcing, climate models commonly project an increase in ISM rainfall. This wetter ISM projection, however, does not consider large model errors in both the mean state and ocean warming pattern. Here we identify a relationship between biases in simulated present climate and future ISM projections in a multi-model ensemble: models with excessive present-day precipitation over the tropical western Pacific tend to project a larger increase in ISM rainfall under GHG forcing because of too strong a negative cloud-radiation feedback on sea surface temperature. The excessive negative feedback suppresses the local ocean surface warming, strengthening ISM rainfall projections via atmospheric circulation. We calibrate the ISM rainfall projections using this 'present-future relationship' and observed western Pacific precipitation. The correction reduces by about 50% of the projected rainfall increase over the broad ISM region. Our study identifies an improved simulation of western Pacific convection as a priority for reliable ISM projections. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved."
"35618134000;55397528100;56971097200;57189358034;9249239700;","Potential impact of carbonaceous aerosol on the upper troposphere and lower stratosphere (UTLS) and precipitation during Asian summer monsoon in a global model simulation",2017,"10.5194/acp-17-11637-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030656704&doi=10.5194%2facp-17-11637-2017&partnerID=40&md5=ea8f1d817f10e336df3261311775057d","Recent satellite observations show efficient vertical transport of Asian pollutants from the surface to the upper-level anticyclone by deep monsoon convection. In this paper, we examine the transport of carbonaceous aerosols, including black carbon (BC) and organic carbon (OC), into the monsoon anticyclone using of ECHAM6-HAM, a global aerosol climate model. Further, we investigate impacts of enhanced (doubled) carbonaceous aerosol emissions on the upper troposphere and lower stratosphere (UTLS), underneath monsoon circulation and precipitation from sensitivity simulations. The model simulation shows that boundary layer aerosols are transported into the monsoon anticyclone by the strong monsoon convection from the Bay of Bengal, southern slopes of the Himalayas and the South China Sea. Doubling of emissions of both BC and OC aerosols over Southeast Asia (10° S-50° N, 65-155° E) shows that lofted aerosols produce significant warming (0.6-1 K) over the Tibetan Plateau (TP) near 400-200 hPa and instability in the middle/upper troposphere. These aerosols enhance radiative heating rates (0.02-0.03Kday-1) near the tropopause. The enhanced carbonaceous aerosols alter aerosol radiative forcing (RF) at the surface by 4.74-1.42Wm-2, at the top of the atmosphere (TOA) by C0.37±0.26Wm-2and in the atmosphere by C5.11±0.83Wm-2over the TP and Indo-Gangetic Plain region (15-35° N, 80-110° E). Atmospheric warming increases vertical velocities and thereby cloud ice in the upper troposphere. Aerosol induced anomalous warming over the TP facilitates the relative strengthening of the monsoon Hadley circulation and increases moisture inflow by strengthening the cross-equatorial monsoon jet. This increases precipitation amounts over India (1-4mmday1/ and eastern China (0.2-2mmday1/. These results are significant at the 99% confidence level."
"35219670500;7102128820;7102425008;","Why are mixed-phase altocumulus clouds poorly predicted by large-scale models? Part 2. Vertical resolution sensitivity and parameterization",2017,"10.1002/2016JD026322","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030184420&doi=10.1002%2f2016JD026322&partnerID=40&md5=4fe84b26b196699feb2efd582273d8f5","Single-column model simulations of mixed-phase altocumulus clouds were shown to have a strong vertical resolution sensitivity in Part 1 of this paper. Coarse-resolution models were unable to simulate the long-lived supercooled liquid layer at cloud top, typically only 200 m thick. In this paper, the sensitivity to vertical resolution is investigated using idealized simulations. Vertical gradients of ice water mixing ratio and temperature near cloud top are found to be inadequately represented at coarse resolution. The vertical discretization using grid box mean values, rather than the full vertical profile, leads to biased calculations of mixed-phase microphysical process rates and affects the diagnosis of thin liquid water layers. As a result, the liquid water layer becomes quickly glaciated and altocumulus cloud lifetime is underestimated. Similar impacts are expected for mixed-phase boundary layer clouds commonly observed at high latitudes. A novel parameterization is introduced that accounts for the vertical gradients of ice water mixing ratio and temperature in the microphysics calculations and the diagnosis of liquid near cloud top. It substantially improves the representation of altocumulus layers in coarse vertical resolution single-column model simulations and reduces the bias identified in Part 1. The new parameterization removes the large underestimate in supercooled water content caused by the resolution sensitivity for temperatures warmer than −30°C. Given the radiative importance of mixed-phase altocumulus clouds, their underestimation by numerical weather prediction models, and their potential to act as a negative climate feedback, there is a need to reevaluate the global climate sensitivity by implementing the findings in these two papers in a climate model. ©2017. American Geophysical Union. All Rights Reserved."
"35219670500;7102128820;7102425008;","Why are mixed-phase altocumulus clouds poorly predicted by large-scale models? Part 1. Physical processes",2017,"10.1002/2016JD026321","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031033911&doi=10.1002%2f2016JD026321&partnerID=40&md5=485a09dd895d483d73f3202537e7d9cd","Mixed-phase layer clouds are radiatively important and their correct representation in numerical models of the atmosphere is needed for both weather forecasts and climate prediction. In particular, midlevel mixed-phase layer clouds (altocumulus) are often poorly predicted. Here the representation of altocumulus cloud in five operational models and the ERA-Interim reanalysis is evaluated using ground-based remote sensors. All models are found to underestimate the supercooled liquid water content by at least a factor of 2. The models with the most sophisticated microphysics (separate prognostic variables for liquid and ice) had least supercooled liquid of all models, though they could simulate the correct liquid-over-ice structure of individual clouds. To investigate the reasons for the lack of predicted supercooled liquid water, a single-column model (EMPIRE) was developed incorporating the relevant physical processes for altocumulus cloud. The supercooled liquid water was found to be the most sensitive to factors that significantly affect the glaciation rate, including aspects of the ice microphysics formulation, as well as the model vertical resolution. Using observations to improve the ice particle size distribution formulation and the parametrization of ice cloud fraction also lead to a significant increase in supercooled liquid water in the simulated clouds. The study highlights the main parameterized processes that need careful attention in large-scale models in order to adequately represent the liquid phase in mixed-phase layer clouds. In Part 2, the reason for the sensitivity to vertical resolution is investigated and a new parameterization for models with coarse vertical resolution is proposed. ©2017. American Geophysical Union. All Rights Reserved."
"56321122100;25624545600;7102128820;35331137500;","Improved rain rate and drop size retrievals from airborne Doppler radar",2017,"10.5194/acp-17-11567-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030479795&doi=10.5194%2facp-17-11567-2017&partnerID=40&md5=acceb14a2c92c48c350ce4f6d1a4c3ac","Satellite remote sensing of rain is important for quantifying the hydrological cycle, atmospheric energy budget, and cloud and precipitation processes; however, radar retrievals of rain rate are sensitive to assumptions about the raindrop size distribution. The upcoming EarthCARE satellite will feature a 94GHz Doppler radar alongside lidar and radiometer instruments, presenting opportunities for enhanced retrievals of the raindrop size distribution. We demonstrate the capability to retrieve rain rate as a function of drop size and drop number concentration from airborne 94GHz Doppler radar measurements using CAPTIVATE, the variational retrieval algorithm developed for EarthCARE. For a range of rain regimes observed during the Tropical Composition, Cloud and Climate Coupling field campaign, we explore the contributions of mean Doppler velocity and path-integrated attenuation (PIA) measurements to the retrieval of rain rate, and the retrievals are evaluated against independent measurements from an independent 9.6GHz Doppler radar. The retrieved drop number concentrations vary over 5 orders of magnitude between very light rain from melting ice and warm rain from liquid clouds. In light rain conditions mean Doppler velocity facilitates estimates of rain rate without PIA, suggesting the possibility of EarthCARE rain rate estimates over land; in moderate warm rain, drop number concentration can be retrieved without mean Doppler velocity, with possible applications to CloudSat. © Author(s) 2017."
"55458623700;55607266000;57189372185;7006204597;","Liquid-liquid phase separation in particles containing secondary organic material free of inorganic salts",2017,"10.5194/acp-17-11261-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029953957&doi=10.5194%2facp-17-11261-2017&partnerID=40&md5=07a1293f928a02c445757f41bcd3406d","Particles containing secondary organic material (SOM) are ubiquitous in the atmosphere and play a role in climate and air quality. Recently, research has shown that liquid-liquid phase separation (LLPS) occurs at high relative humidity (RH) (greater than 95%) in α-pinene-derived SOM particles free of inorganic salts, while LLPS does not occur in isoprene-derived SOM particles free of inorganic salts. We expand on these findings by investigating LLPS at 290±1K in SOM particles free of inorganic salts produced from ozonolysis of β-caryophyllene, ozonolysis of limonene, and photo-oxidation of toluene. LLPS was observed at greater than 95% RH in the biogenic SOM particles derived from β-caryophyllene and limonene while LLPS was not observed in the anthropogenic SOM particles derived from toluene. This work combined with the earlier work on LLPS in SOM particles free of inorganic salts suggests that the occurrence of LLPS in SOM particles free of inorganic salts is related to the oxygen-to-carbon elemental ratio (O:C) of the organic material. These results help explain the difference between the hygroscopic parameter ° of SOM particles measured above and below water saturation in the laboratory and field, and have implications for predicting the cloud condensation nucleation properties of SOM particles. © 2017 Author(s)."
"57195776701;8615886200;25928347900;13204458100;55927053800;36722293600;6603303046;55332145000;55947099700;7006577245;35569803200;","Consistency of aerosols above clouds characterization from A-Train active and passive measurements",2017,"10.5194/amt-10-3499-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029806983&doi=10.5194%2famt-10-3499-2017&partnerID=40&md5=94a69106e7e30c6c1f461d5278cd8c7e","This study presents a comparison between the retrieval of optical properties of aerosol above clouds (AAC) from different techniques developed for the A-Train sensors CALIOP/CALIPSO and POLDER/PARASOL. The main objective is to analyse the consistency between the results derived from the active and the passive measurements. We compare the aerosol optical thickness (AOT) above optically thick clouds (cloud optical thickness (COT) larger than 3) and their Ångström exponent (AE). These parameters are retrieved with the CALIOP operational method, the POLDER operational polarization method and the CALIOP-based depolarization ratio method (DRM)-for which we also propose a calibrated version (denominated DRMSODA, where SODA is the Synergized Optical Depth of Aerosols). We analyse 6 months of data over three distinctive regions characterized by different types of aerosols and clouds. Additionally, for these regions, we select three case studies: A biomass-burning event over the South Atlantic Ocean, a Saharan dust case over the North Atlantic Ocean and a Siberian biomass-burning event over the North Pacific Ocean. Four and a half years of data are studied over the entire globe for distinct situations where aerosol and cloud layers are in contact or vertically separated. Overall, the regional analysis shows a good correlation between the POLDER and the DRMSODA AOTs when the microphysics of aerosols is dominated by fine-mode particles of biomass-burning aerosols from southern Africa (correlation coefficient (2) of 0.83) or coarse-mode aerosols of Saharan dust (2 of 0.82). A good correlation between these methods (2 of 0.68) is also observed in the global treatment, when the aerosol and cloud layers are separated well. The analysis of detached layers also shows a mean difference in AOT of 0.07 at 532nm between POLDER and DRMSODA at a global scale. The correlation between the retrievals decreases when a complex mixture of aerosols is expected (2 of 0.37)-as in the East Asia region-and when the aerosol-cloud layers are in contact (2 of 0.36). The correlation coefficient between the CALIOP operational method and POLDER is found to be low, as the CALIOP method largely underestimates the aerosol loading above clouds by a factor that ranges from 2 to 4. Potential biases on the retrieved AOT as a function of cloud properties are also investigated. For different types of scenes, the retrieval of above-cloud AOT from POLDER and from DRM are compared for different underlying cloud properties (droplet effective radius (eff) and COT retrieved with MODIS). The results reveal that DRM AOT vary with eff. When accounting for eff in the DRM algorithm, the consistency between the methods increases. The sensitivity study shows that an additional polarized signal coming from aerosols located the cloud could affect the polarization method, which leads to an overestimation of the AOT retrieved with POLDER algorithm. In addition, the aerosols to or the cloud can potentially impact the DRM retrievals through the modification of the cloud droplet chemical composition and its ability to backscatter light. The next step of this work is to combine POLDER and CALIOP to investigate the impacts of aerosols on clouds and climate when these particles are transported above or within clouds."
"56707694400;7003614389;21734360900;6701923195;","Effects of shrub and tree cover increase on the near-surface atmosphere in northern Fennoscandia",2017,"10.5194/bg-14-4209-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029819869&doi=10.5194%2fbg-14-4209-2017&partnerID=40&md5=a7c92ed8a04c52e4e881ba432089b4f4","Increased shrub and tree cover in high latitudes is a widely observed response to climate change that can lead to positive feedbacks to the regional climate. In this study we evaluate the sensitivity of the near-surface atmosphere to a potential increase in shrub and tree cover in the northern Fennoscandia region. We have applied the Weather Research and Forecasting (WRF) model with the Noah-UA land surface module in evaluating biophysical effects of increased shrub cover on the near-surface atmosphere at a fine resolution (5.4 km × 5.4 km). Perturbation experiments are performed in which we prescribe a gradual increase in taller vegetation in the alpine shrub and tree cover according to empirically established bioclimatic zones within the study region. We focus on the spring and summer atmospheric response. To evaluate the sensitivity of the atmospheric response to inter-annual variability in climate, simulations were conducted for two contrasting years, one warm and one cold. We find that shrub and tree cover increase leads to a general increase in near-surface temperatures, with the highest influence seen during the snowmelt season and a more moderate effect during summer. We find that the warming effect is stronger in taller vegetation types, with more complex canopies leading to decreases in the surface albedo. Counteracting effects include increased evapotranspiration, which can lead to increased cloud cover, precipitation, and snow cover. We find that the strength of the atmospheric feedback is sensitive to snow cover variations and to a lesser extent to summer temperatures. Our results show that the positive feedback to high-latitude warming induced by increased shrub and tree cover is a robust feature across inter-annual differences in meteorological conditions and will likely play an important role in land-atmosphere feedback processes in the future. © Author(s) 2017."
"15060156600;7102944401;57197275637;7006107059;57189461506;","Rainfall drives atmospheric ice-nucleating particles in the coastal climate of southern Norway",2017,"10.5194/acp-17-11065-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029696396&doi=10.5194%2facp-17-11065-2017&partnerID=40&md5=2284b3c3f0b63b5b0e60578cce1df6d2","Ice-nucleating particles (INPs) active at modest supercooling (e.g. -8 °C; INP-8/ can transform clouds from liquid to mixed phase, even at very small number concentrations (&lt;10m-3/. Over the course of 15 months, we found very similar patterns in weekly concentrations of INP-8 in PM10 (medianD1.7m-3, maximumD10.1m-3/ and weekly amounts of rainfall (medianD28 mm, maximum D153 mm) at Birkenes, southern Norway. Most INP-8 were probably aerosolised locally by the impact of raindrops on plant, litter and soil surfaces. Major snowfall and heavy rain onto snow-covered ground were not mirrored by enhanced numbers of INP-8. Further, transport model calculations for large (&gt;4m-3/ and small (&lt;4m-3/ numbers of INP-8 revealed that potential source regions likely to provide precipitation to southern Norway were associated with large numbers of INP-8. The proportion of land cover and land use type in potential source regions was similar for large and small numbers of INP-8. In PM2:5 we found consistently about half as many INP-8 as in PM10. From mid-May to mid-September, INP-8 correlated positively with the fungal spore markers arabitol and mannitol, suggesting that some fraction of INP-8 during that period may consist of fungal spores. In the future, warmer winters with more rain instead of snow may enhance airborne concentrations of INP-8 during the cold season in southern Norway and in other regions with a similar climate. © Author(s) 2017."
"56041453900;26531622800;24452025200;12239084700;56035904300;57203176082;","Effects of chemical composition and mixing state on size-resolved hygroscopicity and cloud condensation nuclei activity of submicron aerosols at a suburban site in northern Japan in summer",2017,"10.1002/2017JD027286","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030112281&doi=10.1002%2f2017JD027286&partnerID=40&md5=ca4ca46e0d19c98be0a34542c007306f","Ambient hygroscopic properties, numbers of size-segregated cloud condensation nuclei (CCN) at different supersaturations (0.1%–0.8%), and the chemical composition of submicron particles were simultaneously measured at a suburban site in northern Japan in summer. Two distinct periods with different growth factors (GF), CCN activation diameters, and chemical compositions were observed. The data suggest that internally mixed sulfate aerosols dominated the accumulation size mode in relatively aged aerosols during the first period, whereas particles observed during the latter periods showed external mixing dominated by organics, which was linked to low hygroscopicity and CCN activity. In particular, the higher loading of water-soluble organic matter (WSOM; ~60% of OM by mass) with increased WSOM/sulfate ratios corresponded to a low hygroscopicity parameter derived from the CCN measurement (κCCN = 0.15 ± 0.02) at a dry diameter (Ddry) of 146 nm. The results suggest that WSOM, likely dominated by the influence of biogenic sources, contributed to reducing the hygroscopicity and CCN activation at this particle size. Temporal variations in the number concentrations for low GF mode at Ddry = 49.6 nm were similar to those in the elemental carbon (EC) concentration, suggesting that EC contributed to reducing hygroscopicity at this smaller size. Our results suggest that chemical composition and mixing state are important factors controlling the hygroscopicity and CCN activation of submicron particles. These results provide useful data sets of size-resolved subsaturated and supersaturated hygroscopicity and highlight the importance of the abundance of OM relative to sulfate in predicting the effects on climate change. ©2017. American Geophysical Union. All Rights Reserved."
"56181417100;56797006400;23092557500;6603550849;56442784400;55481275400;56181566300;","Size-resolved measurements of mixing state and cloud-nucleating ability of aerosols in Nanjing, China",2017,"10.1002/2017JD026583","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029215501&doi=10.1002%2f2017JD026583&partnerID=40&md5=29b2fadfcacd49421b37ef08dbf0006e","An integrated aerosol analytical system was deployed in Nanjing, a megacity in the Yangtze River Delta, to measure size-resolved aerosol mixing states, effective densities, cloud condensation nucleus (CCN) activities, and chemical composition in August 2013. It was found that aerosols were predominantly internally mixed. The average effective densities were 1.38 ± 0.09, 1.48 ± 0.08, and 1.53 ± 0.07 g cm−3 for 50, 80, and 120 nm particles, respectively. Although black carbon (BC) represented only 0.3%, 1.6%, and 3.3% of the particle mass, on average, it was present in 7%, 38%, and 47% of the total particle number concentration at 50, 80, and 120 nm, respectively, indicating that BC particles may contribute significantly to the total atmospheric aerosol population. Externally mixed BC was only occasionally observed with an effective density of 0.67–0.97 g cm−3. Aerosols sampled generally exhibited a relatively high CCN activity and hygroscopicity (κ = 0.35 ± 0.13). Both newly formed particles and freshly emitted BC particles were observed to age rapidly from photochemical processes, with a significant enhancement in the particle CCN activity and an increase in the effective density. Aerosols influenced by four different air masses presented similar CCN activation, indicating that CCN activation would be primarily dependent on the particle size rather than the particle origin (and hence original composition). Our results suggest that under highly active photochemical conditions as encountered in this study, particles from both local sources and regional transport can be rapidly converted into efficient CCN by photochemical aging, thereby making important contributions to the atmospheric CCN budget and exerting profound implications on aerosol indirect climate forcing. ©2017. American Geophysical Union. All Rights Reserved."
"35595682100;6506246198;8719703500;7103098729;35105101800;6602336407;24779089500;57195923266;7006016266;8255698000;6506886910;57194228711;55605771904;","A case study of convectively sourced water vapor observed in the overworld stratosphere over the United States",2017,"10.1002/2017JD026831","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030128791&doi=10.1002%2f2017JD026831&partnerID=40&md5=f45f4d74f6ba027f4c00aa206902e24b","On 27 August 2013, during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys field mission, NASA's ER-2 research aircraft encountered a region of enhanced water vapor, extending over a depth of approximately 2 km and a minimum areal extent of 20,000 km2 in the stratosphere (375 K to 415 K potential temperature), south of the Great Lakes (42°N, 90°W). Water vapor mixing ratios in this plume, measured by the Harvard Water Vapor instrument, constitute the highest values recorded in situ at these potential temperatures and latitudes. An analysis of geostationary satellite imagery in combination with trajectory calculations links this water vapor enhancement to its source, a deep tropopause-penetrating convective storm system that developed over Minnesota 20 h prior to the aircraft plume encounter. High resolution, ground-based radar data reveal that this system was composed of multiple individual storms, each with convective turrets that extended to a maximum of ~4 km above the tropopause level for several hours. In situ water vapor data show that this storm system irreversibly delivered between 6.6 kt and 13.5 kt of water to the stratosphere. This constitutes a 20–25% increase in water vapor abundance in a column extending from 115 hP to 70 hPa over the plume area. Both in situ and satellite climatologies show a high frequency of localized water vapor enhancements over the central U.S. in summer, suggesting that deep convection can contribute to the stratospheric water budget over this region and season. ©2017. American Geophysical Union. All Rights Reserved."
"34979885900;16678944000;55897579400;6701751765;6701316538;","A warm or a cold early Earth? New insights from a 3-D climate-carbon model",2017,"10.1016/j.epsl.2017.06.029","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030544767&doi=10.1016%2fj.epsl.2017.06.029&partnerID=40&md5=6e4798c1e3594aa384a83cd4e3a690fd","Oxygen isotopes in marine cherts have been used to infer hot oceans during the Archean with temperatures between 60 °C (333 K) and 80 °C (353 K). Such climates are challenging for the early Earth warmed by the faint young Sun. The interpretation of the data has therefore been controversial. 1D climate modeling inferred that such hot climates would require very high levels of CO2 (2–6 bars). Previous carbon cycle modeling concluded that such stable hot climates were impossible and that the carbon cycle should lead to cold climates during the Hadean and the Archean. Here, we revisit the climate and carbon cycle of the early Earth at 3.8 Ga using a 3D climate-carbon model. We find that CO2 partial pressures of around 1 bar could have produced hot climates given a low land fraction and cloud feedback effects. However, such high CO2 partial pressures should not have been stable because of the weathering of terrestrial and oceanic basalts, producing an efficient stabilizing feedback. Moreover, the weathering of impact ejecta during the Late Heavy Bombardment (LHB) would have strongly reduced the CO2 partial pressure leading to cold climates and potentially snowball Earth events after large impacts. Our results therefore favor cold or temperate climates with global mean temperatures between around 8 °C (281 K) and 30 °C (303 K) and with 0.1–0.36 bar of CO2 for the late Hadean and early Archean. Finally, our model suggests that the carbon cycle was efficient for preserving clement conditions on the early Earth without necessarily requiring any other greenhouse gas or warming process. © 2017 Elsevier B.V."
"57194267619;57202755360;7102567334;","Phenology and growth responses of Fraser fir (Abies fraseri) Christmas trees along an elevational gradient, southern Appalachian Mountains, USA",2017,"10.1016/j.agrformet.2017.05.003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019606764&doi=10.1016%2fj.agrformet.2017.05.003&partnerID=40&md5=5ce7518f369adac85785ccb369a2fa83","Fraser fir (Abies fraseri) trees are endemic to locations above 1500 m in the southern Appalachian Mountains, and are also grown commercially for Christmas trees well below their native range (down to 600 m). To evaluate how phenology and growth of this species will respond to climate drivers associated with warming, we assessed the timing of bud-burst, shoot growth, trunk growth, as well as shoot- and leaf-level architecture, of Fraser fir Christmas trees along an elevational gradient from 664 to 1228 m. Daytime maximum temperatures and evaporative demand were highest at low elevation and cloud events and higher wind speeds occurred more often at high elevations. Bud-burst occurred 6 days sooner, new shoots ceased elongation 10 days sooner, and radial trunk growth ended 8 days later at low elevations than at high elevations, indicating a shift and lengthening of the growing season. Final shoot length did not vary among elevations, but the percent increase in trunk diameter was greatest at middle elevations. Architectural characteristics such as specific needle mass, needle packing density, and silhouette-to-projected area ratios generally did not vary with elevation. As climate change progresses, higher cloud ceilings, increased evaporative demand, and higher temperatures may further shift the timing of the growing season and reduce growth at low elevation Christmas tree farms, but farms at higher elevations may benefit from a longer growing season. © 2017 Elsevier B.V."
"57195683737;6602137606;12645700600;23017945100;6701705691;","Radiation in fog: Quantification of the impact on fog liquid water based on ground-based remote sensing",2017,"10.5194/acp-17-10811-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029514645&doi=10.5194%2facp-17-10811-2017&partnerID=40&md5=009bd7fb30292cd950ef872033867f0e","Radiative cooling and heating impact the liquid water balance of fog and therefore play an important role in determining their persistence or dissipation. We demonstrate that a quantitative analysis of the radiation-driven condensation and evaporation is possible in real time using groundbased remote sensing observations (cloud radar, ceilometer, microwave radiometer). Seven continental fog events in midlatitude winter are studied, and the radiative processes are further explored through sensitivity studies. The longwave (LW) radiative cooling of the fog is able to produce 40-70 gm-2 h-1 of liquid water by condensation when the fog liquid water path exceeds 30 gm-2 and there are no clouds above the fog, which corresponds to renewing the fog water in 0.5-2 h. The variability is related to fog temperature and atmospheric humidity, with warmer fog below a drier atmosphere producing more liquid water. The appearance of a cloud layer above the fog strongly reduces the LW cooling relative to a situation with no cloud above; the effect is strongest for a low cloud, when the reduction can reach 100 %. Consequently, the appearance of clouds above will perturb the liquid water balance in the fog and may therefore induce fog dissipation. Shortwave (SW) radiative heating by absorption by fog droplets is smaller than the LW cooling, but it can contribute significantly, inducing 10-15 gm-2 h-1 of evaporation in thick fog at (winter) midday. The absorption of SW radiation by unactivated aerosols inside the fog is likely less than 30% of the SW absorption by the water droplets, in most cases. However, the aerosols may contribute more significantly if the air mass contains a high concentration of absorbing aerosols. The absorbed radiation at the surface can reach 40-120Wm-2 during the daytime depending on the fog thickness. As in situ measurements indicate that 20-40% of this energy is transferred to the fog as sensible heat, this surface absorption can contribute significantly to heating and evaporation of the fog, up to 30 gm-2 h-1 for thin fog, even without correcting for the typical underestimation of turbulent heat fluxes by the eddy covariance method. Since the radiative processes depend mainly on the profiles of temperature, humidity and clouds, the results of this paper are not site specific and can be generalised to fog under different dynamic conditions and formation mechanisms, and the methodology should be applicable to warmer and moister climates as well. The retrieval of approximate emissivity of clouds above fog from cloud radar should be further developed. © 2017 Author(s)."
"37090362900;6603749963;9636594900;7004942632;7402105994;","Regional temperature change potentials for short-lived climate forcers based on radiative forcing from multiple models",2017,"10.5194/acp-17-10795-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029476865&doi=10.5194%2facp-17-10795-2017&partnerID=40&md5=cda6f451841f110fe8a42941cec74505","We calculate the absolute regional temperature change potential (ARTP) of various short-lived climate forcers (SLCFs) based on detailed radiative forcing (RF) calculations from four different models. The temperature response has been estimated for four latitude bands (90-28°S, 28°S-28°N, 28-60°N, and 60-90°N). The regional pattern in climate response not only depends on the relationship between RF and surface temperature, but also on where and when emissions occurred and atmospheric transport, chemistry, interaction with clouds, and deposition. We present four emissions cases covering Europe, East Asia, the global shipping sector, and the entire globe. Our study is the first to estimate ARTP values for emissions during Northern Hemisphere summer (May-October) and winter season (November-April). The species studied are aerosols and aerosol precursors (black carbon, organic carbon, SO2, NH3/, ozone precursors (NOx, CO, volatile organic compound), and methane (CH4/. For the response to BC in the Arctic, we take into account the vertical structure of the RF in the atmosphere, and an enhanced climate efficacy for BC deposition on snow. Of all SLCFs, BC is the most sensitive to where and when the emissions occur, as well as giving the largest difference in response between the latitude bands. The temperature response in the Arctic per unit BC emission is almost four times larger and more than two times larger than the global average for Northern Hemisphere winter emissions for Europe and East Asia, respectively. The latitudinal breakdown likely gives a better estimate of the global temperature response as it accounts for varying efficacies with latitude. An annual pulse of non-methane SLCF emissions globally (representative of 2008) lead to a global cooling. In contrast, winter emissions in Europe and East Asia give a net warming in the Arctic due to significant warming from BC deposition on snow. © 2017 Author(s)."
"6602999057;56522444900;55554574300;57195682350;56682130400;57217801354;35551238800;15319055900;13906443400;7006424590;9536598800;25958833500;57195685805;56073196800;57195676863;56993642000;57195542625;57195683987;57195673296;55226243300;57195675085;","A meteorological and chemical overview of the DACCIWA field campaign in West Africa in June-July 2016",2017,"10.5194/acp-17-10893-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029542737&doi=10.5194%2facp-17-10893-2017&partnerID=40&md5=e27813bffb55d6d1e061df14a953d3d9","In June and July 2016 the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project organised a major international field campaign in southern West Africa (SWA) including measurements from three inland ground supersites, urban sites in Cotonou and Abidjan, radiosondes, and three research aircraft. A significant range of different weather situations were encountered during this period, including the monsoon onset. The purpose of this paper is to characterise the large-scale setting for the campaign as well as synoptic and mesoscale weather systems affecting the study region in the light of existing conceptual ideas, mainly using objective and subjective identification algorithms based on (re-)analysis and satellite products. In addition, it is shown how the described synoptic variations influence the atmospheric composition over SWA through advection of mineral dust, biomass burning and urban pollution plumes. The boreal summer of 2016 was characterised by Pacific La Niña, Atlantic El Niño and warm eastern Mediterranean conditions, whose competing influences on precipitation led to an overall average rainy season. During the relatively dusty pre-onset Phase 1 (1-21 June 2016), three westward-propagating coherent cyclonic vortices between 4 and 13° N modulated winds and rainfall in the Guinea coastal area. The monsoon onset occurred in connection with a marked extratropical trough and cold surge over northern Africa, leading to a breakdown of the Saharan heat low and African easterly jet and a suppression of rainfall. During this period, quasi-stationary low-level vortices associated with the trough transformed into more tropical, propagating disturbances resembling an African easterly wave (AEW). To the east of this system, moist southerlies penetrated deep into the continent. The post-onset Phase 2 (22 June-20 July 2016) was characterised by a significant increase in low-level cloudiness, unusually dry conditions and strong northeastward dispersion of urban pollution plumes in SWA as well as rainfall modulation by westward-propagating AEWs in the Sahel. Around 12-14 July 2016 an interesting and so-far undocumented cyclonic-anticyclonic vortex couplet crossed SWA. The anticyclonic centre had its origin in the Southern Hemisphere and transported unusually dry air filled with aged aerosol into the region. During Phase 3 (21-26 July 2016), a similar vortex couplet slightly farther north created enhanced westerly moisture transports into SWA and extraordinarily wet conditions, accompanied by a deep penetration of the biomass burning plume from central Africa. Finally, a return to more undisturbed monsoon conditions took place during Phase 4 (27-31 July 2016). The in-depth synoptic analysis reveals that several significant weather systems during the DACCIWA campaign cannot be attributed unequivocally to any of the tropical waves and disturbances described in the literature and thus deserve further study. © 2017 Author(s)."
"26029329600;","Direct molecular-level characterization of different heterogeneous freezing modes on mica - Part 1",2017,"10.5194/acp-17-10733-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021672559&doi=10.5194%2facp-17-10733-2017&partnerID=40&md5=a34d0b4b99c84f715d251a486fd9dcad","The mechanisms behind heterogeneous ice nucleation are of fundamental importance to the prediction of the occurrence and properties of many cloud types, which influence climate and precipitation. Aerosol particles act as cloud condensation and freezing nuclei. The surface-water interaction of an ice nucleation particle plays a major, not well explored, role in its ice nucleation ability. This paper presents a real-time molecular-level comparison of different freezing modes on the surface of an atmospherically relevant mineral surface (mica) under varying supersaturation conditions using second-harmonic generation spectroscopy. Two sub-deposition nucleation modes were identified (one- and two-stage freezing). The nonlinear signal at the water-mica interface was found to drop following the formation of a thin film on the surface regardless of (1) the formed phase (liquid or ice) and (2) the freezing path (one or two step), indicating similar molecular structuring. The results also revealed a transient phase of ice at water-mica interfaces during freezing, which has a lifetime of around 1ĝ€min. Such information will have a significant impact on climate change, weather modification, and the tracing of water in hydrosphere studies. © 2017 Author(s)."
"55661093900;57190494123;38762224800;36022842500;56906329400;57198882437;55927490700;37013451200;7601490850;","Wet deposition and scavenging ratio of air pollutants during an extreme rainstorm in the North China Plain",2017,"10.1080/16742834.2017.1343084","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85059674087&doi=10.1080%2f16742834.2017.1343084&partnerID=40&md5=63d0ec119662cbc21a058e24a1240656","Atmospheric wet deposition plays an important role in the supply of nutrients and toxic substances to terrestrial and aquatic environments. Although long-term (e.g. annual, multi-year) wet deposition is recorded well, pronounced and short-term changes in precipitation chemistry are less well investigated. In the present study, the precipitation chemistry and scavenging ratio of air pollutants were observed during an extreme torrential rain event (325.6 mm at the observation site) that occurred over 19–21 July 2016 in the North China Plain (NCP). The scavenging ratio of particles showed a similar spatial distribution to that of the precipitation amount in the NCP, indicating the efficient removal of particulate matter due to the large amount and precipitation intensity of the storm. In addition, the scavenging ratio of water soluble ions was larger than that of organics and gaseous pollutants such as SO2 and NO2, likely due to their differences in water solubility. Consequently, raindrops incorporated more aerosol sulfate than gaseous compounds. Due to the heavy precipitation amount, almost all species in rainwater during this storm showed their lowest concentration but the highest flux compared with other rain events, indicating an important role played by this storm in terms of the substances received by the terrestrial and marine ecosystems of the region. However, the contribution of this storm to the annual chemical flux was lower than that of precipitation amount, indicating that the atmospheric compounds were scavenged below-cloud first and were then diluted by the cloud/rainwater. Future studies are needed in the context of the occurrence of extreme rainfall events in the NCP from the perspective of climate variability. © 2017, © 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group."
"56763440200;56502000100;26639062900;","Computer-controlled Raman microspectroscopy (CC-Raman): A method for the rapid characterization of individual atmospheric aerosol particles",2017,"10.1080/02786826.2017.1337268","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021452278&doi=10.1080%2f02786826.2017.1337268&partnerID=40&md5=802656a48e74f802ffb7f2cde295ccfb","The ability of an atmospheric aerosol particle to impact climate by acting as a cloud condensation nucleus (CCN) or an ice nucleus (IN), as well as scatter and absorb solar radiation is determined by its physicochemical properties at the single particle level, specifically size, morphology, and chemical composition. The identification of the secondary species present in individual aerosol particles is important as aging, which leads to the formation of these species, can modify the climate relevant behavior of particles. Raman microspectroscopy has a great deal of promise for identifying secondary species and their mixing with primary components, as it can provide detailed information on functional groups present, morphology, and internal structure. However, as with many other detailed spectroscopic techniques, manual analysis by Raman microspectroscopy can be slow, limiting single particle statistics and the number of samples that can be analyzed. Herein, the application of computer-controlled Raman (CC-Raman) for detailed physicochemical analysis that increases throughput and minimizes user bias is described. CC-Raman applies automated mapping to increase analysis speed allowing for up to 100 particles to be analyzed in an hour. CC-Raman is applied to both laboratory and ambient samples to demonstrate its utility for the analysis of both primary and, most importantly, secondary components (sulfate, nitrate, ammonium, and organic material). Reproducibility and precision are compared to computer controlled-scanning electron microscopy (CCSEM). The greater sample throughput shows the potential for CC-Raman to improve particle statistics and advance our understanding of aerosol particle composition and mixing state, and, thus, climate-relevant properties. © 2017 American Association for Aerosol Research. © 2017 American Association for Aerosol Research."
"57210687618;56375331500;7004247643;","Suppression of Arctic air formation with climate warming: Investigation with a two-dimensional cloud-resolving model",2017,"10.1175/JAS-D-16-0193.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029104750&doi=10.1175%2fJAS-D-16-0193.1&partnerID=40&md5=ab222b14eeb5a23798914fd901ef03f1","Arctic climate change in winter is tightly linked to changes in the strength of surface temperature inversions, which occur frequently in the present climate as Arctic air masses form during polar night. Recent work proposed that, in a warmer climate, increasing low-cloud optical thickness of maritime air advected over highlatitude landmasses during polar night could suppress the formation of Arctic air masses, amplifying winter warming over continents and sea ice. But this mechanism was based on single-column simulations that could not assess the role of fractional cloud cover change. This paper presents two-dimensional cloud-resolving model simulations that support the single-column model results: low-cloud optical thickness and duration increase strongly with initial air temperature, slowing the surface cooling rate as the climate is warmed. The cloud-resolving model cools less at the surface than the single-column model, and the sensitivity of its cooling to warmer initial temperatures is also higher, because it produces cloudier atmospheres with stronger lowertropospheric mixing and distributes cloud-top cooling over a deeper atmospheric layer with larger heat capacity. Resolving larger-scale cloud turbulence has the greatest impact on the microphysics schemes that best represent general observed features of mixed-phase clouds, increasing their sensitivity to climate warming. These findings support the hypothesis that increasing insulation of the high-latitude land surface by low clouds in a warmer world could act as a strong positive feedback in future climate change and suggest studying Arctic air formation in a three-dimensional climate model. © 2017 American Meteorological Society."
"57195590505;25823927100;19638935200;56424145700;7103158465;25031430500;","A single ice approach using varying ice particle properties in global climate model microphysics",2017,"10.1002/2017MS000952","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028953494&doi=10.1002%2f2017MS000952&partnerID=40&md5=3cb59bc5700e7c92564ce09a9d65eaaa","Ice and mixed-phase cloud representation and simulation in global climate models are challenging with large uncertainties and biases. Sharing similar growth paths, no distinct separation exists in nature between cloud ice and snow. Different from conventional microphysics schemes separating cloud ice from snow, a single prognostic category is used to represent the whole spectrum of solid hydrometeors. Instead of using fixed physical properties for separate ice classes, e.g., the mass, area, and fall velocity, we consider the particle shape and riming impacts on ice properties. This approach simplifies several ice-related microphysical processes and eliminates the ambiguity and uncertainty associated with parameterizing cloud ice to snow conversion. The modifications were implemented in the Morrison-Gettelman (MG08) scheme and tested in Community Atmosphere Model. Evaluation using single column simulations indicated that the new approach increased the ice water content (IWC) in high clouds during dry period, which is improved compared to available retrievals. Global atmospheric simulations using the new approach give an overall comparable mean climate with notable improvement in terms of clouds and their radiative forcing. Both longwave and shortwave cloud forcing are closer to observations due to more realistic IWC, liquid water content, and cloud top height. Furthermore, the new approach yields slightly better representation of mixed-phase clouds when a smaller capacitance for nonspherical particles is used in the ice depositional growth parameterization. Overall, the physically based single-ice approach is a promising direction for future GCM microphysics development given its simplified representation of microphysical processes and flexible description of ice particle properties. © 2017. The Authors."
"56898396100;23028245500;15051249600;7004057920;55574869900;","The warming of Tibetan Plateau enhanced by 3D variation of low-level clouds during daytime",2017,"10.1016/j.rse.2017.06.024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021662587&doi=10.1016%2fj.rse.2017.06.024&partnerID=40&md5=b49b3042184ea5ae0067f9fa8fc4c714","The Tibetan Plateau (TP) has experienced evident warming in recent decades, but the exact reasons for this warming remain unclear. In this study, we investigated the possible effect of the three-dimensional (3D) variations of cloud during daytime on climate warming over the TP from 2007 to 2015 based on CloudSat and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations. We found that the 3D changes occur mostly to low clouds, whose fraction and geometrical depth decrease by approximately 4.2% and 130 m, respectively. These changes result in the increase of the surface shortwave radiation (SSR) by approximately 29.7 W/m2, which is one magnitude larger than that of anthropogenic CO2. The increase in SSR leads to the increase in direct solar radiation absorption in the surface, which significantly enhances the warming of the TP. © 2016"
"8920681600;36671874400;54995785000;57203053066;","Extra-tropical origin of equatorial Pacific cold bias in climate models with links to cloud albedo",2017,"10.1007/s00382-016-3435-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994706943&doi=10.1007%2fs00382-016-3435-6&partnerID=40&md5=e8e28f284a7f0630b24bc8e04f4b12e5","General circulation models frequently suffer from a substantial cold bias in equatorial Pacific sea surface temperatures (SSTs). For instance, the majority of the climate models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) have this particular problem (17 out of the 26 models evaluated in the present study). Here, we investigate the extent to which these equatorial cold biases are related to mean climate biases generated in the extra-tropics and then communicated to the equator via the oceanic subtropical cells (STCs). With an evident relationship across the CMIP5 models between equatorial SSTs and upper ocean temperatures in the extra-tropical subduction regions, our analysis suggests that cold SST biases within the extra-tropical Pacific indeed translate into a cold equatorial bias via the STCs. An assessment of the relationship between these extra-tropical SST biases and local surface heat flux components indicates a link to biases in the simulated shortwave fluxes. Further sensitivity studies with a climate model (CESM) in which extra-tropical cloud albedo is systematically varied illustrate the influence of cloud albedo perturbations, not only directly above the oceanic subduction regions but across the extra-tropics, on the equatorial bias. The CESM experiments reveal a quadratic relationship between extra-tropical Pacific albedo and the root-mean-square-error in equatorial SSTs—a relationship with which the CMIP5 models generally agree. Thus, our study suggests that one way to improve the equatorial cold bias in the models is to improve the representation of subtropical and mid-latitude cloud albedo. © 2016, Springer-Verlag Berlin Heidelberg."
"57189495284;7404178566;15050523700;15047538100;10045312900;37021754000;39261812300;","Assessment of simulation of radiation in NCEP Climate Forecasting System (CFS V2)",2017,"10.1016/j.atmosres.2017.04.013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017476979&doi=10.1016%2fj.atmosres.2017.04.013&partnerID=40&md5=708ee03a780f3ec261ed30233f865b5e","The objective of this study is to identify and document the radiation biases in the latest National Centers for Environment Prediction (NCEP), Climate Forecasting System (CFSv2) and to investigate the probable reasons for these biases. This analysis is made over global and Indian domain under all-sky and clear-sky conditions. The impact of increasing the horizontal resolution of the atmospheric model on these biases is also investigated by comparing results of two different horizontal resolution versions of CFSv2 namely T126 and T382. The difference between the top of the atmosphere and surface energy imbalance in T126 (T382) is 3.49 (2.78) W/m2. This reduction of bias in the high resolution model is achieved due to lesser low cloud cover, resulting more surface insolation, and due to more latent heat fluxes at the surface. Compared to clear sky simulations, all sky simulations exhibit larger biases suggesting that the cloud covers are not simulated well in the model. The annual mean high level cloud cover is over estimated over the global as well as the Indian domain. This overestimation over the Indian domain is also present during JJAS. There is also evidence that both of the models have insufficient water vapour in their atmosphere. This study suggests that in order to improve the model's mean radiation climatology, simulation of clouds in the model also needs to be improved, and future model development activities should focus on this aspect. © 2017 Elsevier B.V."
"57212781009;57191914668;","On the relative strength of radiative feedbacks under climate variability and change",2017,"10.1007/s00382-016-3441-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994761694&doi=10.1007%2fs00382-016-3441-8&partnerID=40&md5=452f86d7a2a2c9c20f1bf097ae308adb","Using the method of radiative ‘kernels’, an analysis is made of feedbacks in models participating in the World Climate Research Program Coupled Model Intercomparison Project phase 5. Feedbacks are calculated for RCP8.5 and abrupt4xCO2 experiments as well as for interannual and decadal variability from pre-industrial runs. Regressions across models are used to elicit relationships across experiments/timescales. Feedbacks between RCP8.5 and abrupt4xCO2 experiments show strong relationships, as expected from surface temperature response similarities arising from the two experiments. The analysis also reveals significant relationships between RCP8.5 and decadal and interannual lapse rate feedback, decadal water vapour and interannual total cloud—the latter confirming results elsewhere. To reveal the impact of warming pattern differences, ‘synthetic’ feedbacks are also generated, based on RCP8.5, whereby local feedbacks determined from that experiment are scaled by relative temperature changes (per degree of global warming) from the others. The synthetic feedbacks indicate that the (sometimes strongly) differing temperature response patterns themselves should not preclude strong correlations between variability and climate change feedbacks—indeed such correlations would be close if local feedbacks were a robust feature of the climate. Although such close correlations are not manifest, the synthetic feedbacks predict the interannual and decadal feedbacks to some extent (are correlated across models), and reveal the consistency, to a first approximation, of the mean model strength of variability feedbacks. Although cloud feedbacks at interannual timescales are correlated with those from RCP8.5, and show consistency with the strength of synthetic feedbacks, separate long and short wave components reveal very different, compensating, latitudinal patterns, suggesting the close correlation may be fortuitous. © 2016, Springer-Verlag Berlin Heidelberg."
"7403282069;57195591631;8977001000;8882641700;16029674800;","Differences in the hydrological cycle and sensitivity between multiscale modeling frameworks with and without a higher-order turbulence closure",2017,"10.1002/2017MS000970","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029001695&doi=10.1002%2f2017MS000970&partnerID=40&md5=0cf3baeea27e8d4a29448b9952346a4f","Current conventional global climate models (GCMs) produce a weak increase in global-mean precipitation with anthropogenic warming in comparison with the lower tropospheric moisture increases. The motive of this study is to understand the differences in the hydrological sensitivity between two multiscale modeling frameworks (MMFs) that arise from the different treatments of turbulence and low clouds in order to aid to the understanding of the model spread among conventional GCMs. We compare the hydrological sensitivity and its energetic constraint from MMFs with (SPCAM-IPHOC) or without (SPCAM) an advanced higher-order turbulence closure. SPCAM-IPHOC simulates higher global hydrological sensitivity for the slow response but lower sensitivity for the fast response than SPCAM. Their differences are comparable to the spreads of conventional GCMs. The higher sensitivity in SPCAM-IPHOC is associated with the higher ratio of the changes in latent heating to those in net atmospheric radiative cooling, which is further related to a stronger decrease in the Bowen ratio with warming than in SPCAM. The higher sensitivity of cloud radiative cooling resulting from the lack of low clouds in SPCAM is another major factor in contributing to the lower precipitation sensitivity. The two MMFs differ greatly in the hydrological sensitivity over the tropical lands, where the simulated sensitivity of surface sensible heat fluxes to surface warming and CO2 increase in SPCAM-IPHOC is weaker than in SPCAM. The difference in divergences of dry static energy flux simulated by the two MMFs also contributes to the difference in land precipitation sensitivity between the two models. © 2017. The Authors."
"35917842100;7404577357;8453485500;35481796400;15829150100;6603822406;57189262877;7202607288;25647475300;55947319900;","Large ice particles associated with small ice water content observed by AIM CIPS imagery of polar mesospheric clouds: Evidence for microphysical coupling with small-scale dynamics",2017,"10.1016/j.jastp.2016.04.018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966891782&doi=10.1016%2fj.jastp.2016.04.018&partnerID=40&md5=22dfe6d88f33bfe899c75f2896e6b684","Observations by the Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) satellite have demonstrated the existence of Polar Mesospheric Cloud (PMC) regions populated by particles whose mean sizes range between 60 and 100 nm (radii of equivalent volume spheres). It is known from numerous satellite experiments that typical mean PMC particle sizes are of the order of 40–50 nm. Determination of particle size by CIPS is accomplished by measuring the scattering of solar radiation at various scattering angles at a spatial resolution of 25 km2. In this size range we find a robust anti-correlation between mean particle size and albedo. These very-large particle-low-ice (VLP-LI) clouds occur over spatially coherent areas. The surprising result is that VLP-LI are frequently present either in the troughs of gravity wave-like features or at the edges of PMC voids. We postulate that an association with gravity waves exists in the low-temperature summertime mesopause region, and illustrate the mechanism by a gravity wave simulation through use of the 2D Community Aerosol and Radiation Model for Atmospheres (CARMA). The model results are consistent with a VLP-LI population in the cold troughs of monochromatic gravity waves. In addition, we find such events in Whole Earth Community Climate Model/CARMA simulations, suggesting the possible importance of sporadic downward winds in heating the upper cloud regions. This newly-discovered association enhances our understanding of the interaction of ice microphysics with dynamical processes in the upper mesosphere. © 2016"
"55332348600;26645289600;7402064802;","Analyzing the dependence of global cloud feedback on the spatial pattern of sea surface temperature change with a Green's function approach",2017,"10.1002/2017MS001096","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029445530&doi=10.1002%2f2017MS001096&partnerID=40&md5=820bc92c099cded22f1a3f1aee63a5e3","The spatial pattern of sea surface temperature (SST) changes has a large impact on the magnitude of cloud feedback. In this study, we seek a basic understanding of the dependence of cloud feedback on the spatial pattern of warming. Idealized experiments are carried out with an AGCM to calculate the change in global mean cloud-induced radiation anomalies (ΔRcloud) in response to imposed surface warming/cooling in 74 individual localized oceanic “patches”. Then the cloud feedback in response to a specific warming pattern can be approximated as the superposition of global cloud feedback in response to a temperature change in each region, weighted by the magnitude of the local temperature changes. When there is a warming in the tropical subsidence or extratropical regions, the local decrease of LCC results in a positive change in Rcloud. Conversely, warming in tropical ascent regions increases the free-tropospheric temperature throughout the tropics, thereby enhancing the inversion strength over remote regions and inducing positive global low-cloud cover (LCC) anomalies and negative Rcloud anomalies. The Green's function approach performs reasonably well in predicting the response of global mean ΔLCC and net ΔRcloud, but poorly for shortwave and longwave components of ΔRcloud due to its ineffectiveness in predicting middle and high cloud cover changes. The approach successfully captures the change of cloud feedback in response to time-evolving CO2-induced warming and captures the interannual variations in ΔRcloud observed by CERES. The results highlight important nonlocal influences of SST changes on cloud feedback. © 2017. The Authors."
"56435178300;55731064200;57191586727;","Roles of energy conservation and climate feedback in Bjerknes compensation: a coupled modeling study",2017,"10.1007/s00382-016-3386-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991628096&doi=10.1007%2fs00382-016-3386-y&partnerID=40&md5=084d400286289e0e5c618fb140574f71","The roles of energy balance and climate feedback in Bjerknes compensation (BJC) are studied through wind-perturbation experiments in a coupled climate model. Shutting down surface winds over the ocean causes significant reductions in both wind-driven and thermohaline overturning circulations, leading to a remarkable decrease in poleward ocean heat transport (OHT). The sea surface temperature (SST) responds with an increasing meridional gradient, resulting in a stronger Hadley Cell, and thus an enhanced atmosphere heat transport (AHT), compensating the OHT decrease. This is the so-called BJC. Coupled model experiments confirm that the occurrence of BJC is an intrinsic requirement of local energy conservation, and local climate feedback determines the degree of BJC, consistent with our previous theoretical results. Negative (positive or zero) local feedback results in AHT change undercompensating (overcompensating or perfectly compensating) OHT change. Using the radiative kernel technique, the general local feedback between the radiative balance at the top of the atmosphere and surface temperature can be partitioned into individual feedbacks that are related to perturbations in temperature, water vapor, surface albedo, and clouds. We find that the overcompensation in the tropics (extratropics) is mainly caused by positive feedbacks related to water vapor and clouds (surface albedo). The longwave feedbacks related to SST and atmospheric temperature are always negative and strong outside the tropics, well offsetting positive feedbacks in most regions and resulting in undercompensation. Different dominant feedbacks give different BJC scenarios at different regions, acting together to maintain the local energy balance. © 2016, The Author(s)."
"56089348800;16475714800;","The physics of orographic elevated heating in radiative-convective equilibrium",2017,"10.1175/JAS-D-16-0312.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026291548&doi=10.1175%2fJAS-D-16-0312.1&partnerID=40&md5=2b33c63f5ea17e115afc0160d9d9d613","Elevated heating of the atmosphere by large plateaus has been argued to influence regional climate in Asia and other regions, but the mechanisms that cause the troposphere to equilibrate at warmer temperatures over elevated terrain are not well understood. This paper quantitatively describes the physics that controls temperatures over elevated terrain in radiative-convective equilibrium (RCE). First, a cloud-system-resolving model (CSRM) is used to simulate RCE states over surfaces with various elevations. Then, a theory for the influence of surface elevation on temperatures in RCE is presented. Together with offline radiative transfer calculations, this theory is used to quantitatively attribute the magnitude of the elevated heating effect to topof- atmosphere radiative flux changes caused by decreases in longwave absorption, shortwave scattering, and the moist lapse rate that occur as surface pressure drops. Sensitivity functions obtained through these offline calculations suggest that elevated heating is weaker in warmer climates, and additional CSRM simulations support this hypothesis. Under certain circumstances, even the sign of the elevated heating effect can change to produce cooler temperatures at a given pressure level as the surface is lifted in RCE. © 2017 American Meteorological Society."
"24366038500;22954523900;8927405700;7003375617;","Target categorization of aerosol and clouds by continuous multiwavelength-polarization lidar measurements",2017,"10.5194/amt-10-3175-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017628607&doi=10.5194%2famt-10-3175-2017&partnerID=40&md5=df19edcc67640481765aa75e7355d14c","Absolute calibrated signals at 532 and 1064 nm and the depolarization ratio from a multiwavelength lidar are used to categorize primary aerosol but also clouds in high temporal and spatial resolution. Automatically derived particle backscatter coefficient profiles in low temporal resolution (30 min) are applied to calibrate the lidar signals. From these calibrated lidar signals, new atmospheric parameters in temporally high resolution (quasi-particle-backscatter coefficients) are derived. By using thresholds obtained from multiyear, multisite EARLINET (European Aerosol Research Lidar Network) measurements, four aerosol classes (small; large, spherical; large, non-spherical; mixed, partly nonspherical) and several cloud classes (liquid, ice) are defined. Thus, particles are classified by their physical features (shape and size) instead of by source. The methodology is applied to 2 months of continuous observations (24 h a day, 7 days a week) with the multiwavelength-Raman-polarization lidar PollyXT during the High-Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE) in spring 2013. Cloudnet equipment was operated continuously directly next to the lidar and is used for comparison. By discussing three 24 h case studies, it is shown that the aerosol discrimination is very feasible and informative and gives a good complement to the Cloudnet target categorization. Performing the categorization for the 2-month data set of the entire HOPE campaign, almost 1 million pixel (5 min×30 m) could be analysed with the newly developed tool. We find that the majority of the aerosol trapped in the planetary boundary layer (PBL) was composed of small particles as expected for a heavily populated and industrialized area. Large, spherical aerosol was observed mostly at the top of the PBL and close to the identified cloud bases, indicating the importance of hygroscopic growth of the particles at high relative humidity. Interestingly, it is found that on several days non-spherical particles were dispersed from the ground into the atmosphere. © 2017 Author(s)."
"56158622800;57207039852;7402803216;35271403600;55087038900;7005231450;57205356666;18434662400;7401967617;7409080503;56123335600;55913339000;24476647200;56073100500;55913917200;23970605900;12239740000;56699083600;55346507200;57213947466;35286080700;","Dryland climate change: Recent progress and challenges",2017,"10.1002/2016RG000550","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031943704&doi=10.1002%2f2016RG000550&partnerID=40&md5=b2e9ed5a4ff74159b9574e4e7208f9da","Drylands are home to more than 38% of the world's population and are one of the most sensitive areas to climate change and human activities. This review describes recent progress in dryland climate change research. Recent findings indicate that the long-term trend of the aridity index (AI) is mainly attributable to increased greenhouse gas emissions, while anthropogenic aerosols exert small effects but alter its attributions. Atmosphere-land interactions determine the intensity of regional response. The largest warming during the last 100 years was observed over drylands and accounted for more than half of the continental warming. The global pattern and interdecadal variability of aridity changes are modulated by oceanic oscillations. The different phases of those oceanic oscillations induce significant changes in land-sea and north-south thermal contrasts, which affect the intensity of the westerlies and planetary waves and the blocking frequency, thereby altering global changes in temperature and precipitation. During 1948–2008, the drylands in the Americas became wetter due to enhanced westerlies, whereas the drylands in the Eastern Hemisphere became drier because of the weakened East Asian summer monsoon. Drylands as defined by the AI have expanded over the last 60 years and are projected to expand in the 21st century. The largest expansion of drylands has occurred in semiarid regions since the early 1960s. Dryland expansion will lead to reduced carbon sequestration and enhanced regional warming. The increasing aridity, enhanced warming, and rapidly growing population will exacerbate the risk of land degradation and desertification in the near future in developing countries. ©2017. American Geophysical Union. All Rights Reserved."
"7402333662;57203109046;6506476612;55746507000;","Sensitivity of gravity wave fluxes to interannual variations in tropical convection and zonal wind",2017,"10.1175/JAS-D-17-0044.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029043432&doi=10.1175%2fJAS-D-17-0044.1&partnerID=40&md5=058cd1ff5b92177c5de054e76f9eaad7","Using an idealized model framework with high-frequency tropical latent heating variability derived from global satellite observations of precipitation and clouds, the authors examine the properties and effects of gravity waves in the lower stratosphere, contrasting conditions in an El Niño year and a La Niña year. The model generates a broad spectrum of tropical waves including planetary-scale waves through mesoscale gravity waves. The authors compare modeled monthly mean regional variations in wind and temperature with reanalyses and validate the modeled gravity waves using satellite- and balloon-based estimates of gravity wave momentum flux. Some interesting changes in the gravity spectrum of momentum flux are found in the model, which are discussed in terms of the interannual variations in clouds, precipitation, and large-scale winds. While regional variations in clouds, precipitation, and winds are dramatic, the mean gravity wave zonal momentum fluxes entering the stratosphere differ by only 11%. The modeled intermittency in gravity wave momentum flux is shown to be very realistic compared to observations, and the largest-amplitude waves are related to significant gravity wave drag forces in the lowermost stratosphere. This strong intermittency is generally absent or weak in climate models because of deficiencies in parameterizations of gravity wave intermittency. These results suggest a way forward to improve model representations of the lowermost stratospheric quasi-biennial oscillation winds and teleconnections. © 2017 American Meteorological Society."
"7006091410;56414303000;57195769430;35086923800;","High resolution projections for the western Iberian coastal low level jet in a changing climate",2017,"10.1007/s00382-016-3397-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991764200&doi=10.1007%2fs00382-016-3397-8&partnerID=40&md5=36bed2e8192ce307a1ba7072c4db6779","The Iberian coastal low-level jet (CLLJ) is one of the less studied boundary layer wind jet features in the Eastern Boundary Currents Systems (EBCS). These regions are amongst the most productive ocean ecosystems, where the atmosphere–land–ocean feedbacks, which include marine boundary layer clouds, coastal jets, upwelling and inland soil temperature and moisture, play an important role in defining the regional climate along the sub-tropical mid-latitude western coastal areas. Recently, the present climate western Iberian CLLJ properties were extensively described using a high resolution regional climate hindcast simulation. A summer maximum frequency of occurrence above 30 % was found, with mean maximum wind speeds around 15 ms−1, between 300 and 400 m heights (at the jet core). Since the 1990s the climate change impact on the EBCS is being studied, nevertheless some lack of consensus still persists regarding the evolution of upwelling and other components of the climate system in these areas. However, recently some authors have shown that changes are to be expected concerning the timing, intensity and spatial homogeneity of coastal upwelling, in response to future warming, especially at higher latitudes, namely in Iberia and Canaries. In this study, the first climate change assessment study regarding the Western Iberian CLLJ, using a high resolution (9 km) regional climate simulation, is presented. The properties of this CLLJ are studied and compared using two 30 years simulations: one historical simulation for the 1971–2000 period, and another simulation for future climate, in agreement with the RCP8.5 scenario, for the 2071–2100 period. Robust and consistent changes are found: (1) the hourly frequency of occurrence of the CLLJ is expected to increase in summer along the western Iberian coast, from mean maximum values of around 35 % to approximately 50 %; (2) the relative increase of the CLLJ frequency of occurrence is higher in the north off western Iberia; (3) the occurrence of the CLLJ covers larger areas both latitudinal and longitudinal; (4) the CLLJ season is lengthened extending to May and September; and, (5) there are shifts for higher occurrences of higher wind speeds and for the jet core to occur at higher heights. © 2016, Springer-Verlag Berlin Heidelberg."
"57193652896;8839237600;57203382356;57194682122;7004379793;","Tropical Montane Cloud Forests: Hydrometeorological variability in three neighbouring catchments with different forest cover",2017,"10.1016/j.jhydrol.2017.06.023","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021667276&doi=10.1016%2fj.jhydrol.2017.06.023&partnerID=40&md5=9cca88167975ec49a060f2c019ee88b3","Mountain areas are characterized by a large heterogeneity in hydrological and meteorological conditions. This heterogeneity is currently poorly represented by gauging networks and by the coarse scale of global and regional climate and hydrological models. Tropical Montane Cloud Forests (TMCFs) are found in a narrow elevation range and are characterized by persistent fog. Their water balance depends on local and upwind temperatures and moisture, therefore, changes in these parameters will alter TMCF hydrology. Until recently the hydrological functioning of TMCFs was mainly studied in coastal regions, while continental TMCFs were largely ignored. This study contributes to fill this gap by focusing on a TMCF which is located on the northern eastern Andes at an elevation of 1550–2300 m asl, in the Orinoco river basin highlands. In this study, we describe the spatial and seasonal meteorological variability, analyse the corresponding catchment hydrological response to different land cover, and perform a sensitivity analysis on uncertainties related to rainfall interpolation, catchment area estimation and streamflow measurements. Hydro-meteorological measurements, including hourly solar radiation, temperature, relative humidity, wind speed, precipitation, soil moisture and streamflow, were collected from June 2013 to May 2014 at three gauged neighbouring catchments with contrasting TMCF/grassland cover and less than 250 m elevation difference. We found wetter and less seasonally contrasting conditions at higher elevations, indicating a positive relation between elevation and fog or rainfall persistence. This pattern is similar to that of other eastern Andean TMCFs, however, the study site had higher wet season rainfall and lower dry season rainfall suggesting that upwind contrasts in land cover and moisture can influence the meteorological conditions at eastern Andean TMCFs. Contrasting streamflow dynamics between the studied catchments reflect the overall system response as a function of the catchments’ elevation and land cover. The forested catchment, located at the higher elevations, had the highest seasonal streamflows. During the wet season, different land covers at the lower elevations were important in defining the streamflow responses between the deforested catchment and the catchment with intermediate forest cover. Streamflows were higher and the rainfall-runoff responses were faster in the deforested catchment than in the intermediate forest cover catchment. During the dry season, the catchments’ elevation defined streamflows due to higher water inputs and lower evaporative demand at the higher elevations. © 2017 Elsevier B.V."
"7103386012;7003279098;56465386500;56026569200;57195218855;57191077410;","Dimethylsulfide model calibration and parametric sensitivity analysis for the Greenland Sea",2017,"10.1016/j.polar.2017.07.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026329819&doi=10.1016%2fj.polar.2017.07.001&partnerID=40&md5=bfecef7bb3656272f649f513bb8e3253","Sea-to-air fluxes of marine biogenic aerosols have the potential to modify cloud microphysics and regional radiative budgets, and thus moderate Earth's warming. Polar regions play a critical role in the evolution of global climate. In this work, we use a well-established biogeochemical model to simulate the DMS flux from the Greenland Sea (20°W–10°E and 70°N–80°N) for the period 2003–2004. Parameter sensitivity analysis is employed to identify the most sensitive parameters in the model. A genetic algorithm (GA) technique is used for DMS model parameter calibration. Data from phase 5 of the Coupled Model Intercomparison Project (CMIP5) are used to drive the DMS model under 4 × CO2 conditions. DMS flux under quadrupled CO2 levels increases more than 300% compared with late 20th century levels (1 × CO2). Reasons for the increase in DMS flux include changes in the ocean state—namely an increase in sea surface temperature (SST) and loss of sea ice—and an increase in DMS transfer velocity, especially in spring and summer. Such a large increase in DMS flux could slow the rate of warming in the Arctic via radiative budget changes associated with DMS-derived aerosols. © 2017 Elsevier B.V. and NIPR"
"55928055700;55887366800;35758381900;55918993800;","A glimpse at short-term controls of evapotranspiration along the southern slopes of Kilimanjaro",2017,"10.1007/s10661-017-6179-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028424831&doi=10.1007%2fs10661-017-6179-9&partnerID=40&md5=32e1242d743959a9592a86713caae2fe","Future climate characteristics of the southern Kilimanjaro region, Tanzania, are mainly determined by local land-use and global climate change. Reinforcing increasing dryness throughout the twentieth century, ongoing land transformation processes emphasize the need for a proper understanding of the regional-scale water budget and possible implications on related ecosystem functioning and services. Here, we present an analysis of scintillometer-based evapotranspiration (ET) covering seven distinct habitat types across a massive climate gradient from the colline savanna woodlands to the upper-mountain Helichrysum zone (940 to 3960 m.a.s.l.). Random forest-based mean variable importance indicates an outstanding significance of net radiation (Rnet) on the observed ET across all elevation levels. Accordingly, topography and frequent cloud/fog events have a dampening effect at high elevations, whereas no such constraints affect the energy and moisture-rich submontane coffee/grassland level. By contrast, long-term moisture availability is likely to impose restrictions upon evapotranspirative net water loss in savanna, which particularly applies to the pronounced dry season. At plot scale, ET can thereby be approximated reasonably using Rnet, soil heat flux, and to a lesser degree, vapor pressure deficit and rainfall as predictor variables (R2 0.59 to 1.00). While multivariate regression based on pooled meteorological data from all plots proves itself useful for predicting hourly ET rates across a broader range of ecosystems (R2 = 0.71), additional gains in explained variance can be achieved when vegetation characteristics as seen from the NDVI are considered (R2 = 0.87). To sum up, our results indicate that valuable insights into land cover-specific ET dynamics, including underlying drivers, may be derived even from explicitly short-term measurements in an ecologically highly diverse landscape. © 2017, The Author(s)."
"48261068400;7402170368;57206741690;57195294322;57192589807;56146653300;22956851400;26028957000;56376088100;48261647000;57195292604;16643520600;37040014000;12544553500;7004251030;","A mangrove forest map of China in 2015: Analysis of time series Landsat 7/8 and Sentinel-1A imagery in Google Earth Engine cloud computing platform",2017,"10.1016/j.isprsjprs.2017.07.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026835094&doi=10.1016%2fj.isprsjprs.2017.07.011&partnerID=40&md5=ea46b02601f0f20b94b03805cce68157","Due to rapid losses of mangrove forests caused by anthropogenic disturbances and climate change, accurate and contemporary maps of mangrove forests are needed to understand how mangrove ecosystems are changing and establish plans for sustainable management. In this study, a new classification algorithm was developed using the biophysical characteristics of mangrove forests in China. More specifically, these forests were mapped by identifying: (1) greenness, canopy coverage, and tidal inundation from time series Landsat data, and (2) elevation, slope, and intersection-with-sea criterion. The annual mean Normalized Difference Vegetation Index (NDVI) was found to be a key variable in determining the classification thresholds of greenness, canopy coverage, and tidal inundation of mangrove forests, which are greatly affected by tide dynamics. In addition, the integration of Sentinel-1A VH band and modified Normalized Difference Water Index (mNDWI) shows great potential in identifying yearlong tidal and fresh water bodies, which is related to mangrove forests. This algorithm was developed using 6 typical Regions of Interest (ROIs) as algorithm training and was run on the Google Earth Engine (GEE) cloud computing platform to process 1941 Landsat images (25 Path/Row) and 586 Sentinel-1A images circa 2015. The resultant mangrove forest map of China at 30 m spatial resolution has an overall/users/producer's accuracy greater than 95% when validated with ground reference data. In 2015, China's mangrove forests had a total area of 20,303 ha, about 92% of which was in the Guangxi Zhuang Autonomous Region, Guangdong, and Hainan Provinces. This study has demonstrated the potential of using the GEE platform, time series Landsat and Sentine-1A SAR images to identify and map mangrove forests along the coastal zones. The resultant mangrove forest maps are likely to be useful for the sustainable management and ecological assessments of mangrove forests in China. © 2017"
"56951139400;51864663400;56520921400;","Simultaneous characterization of mesoscale and convective-scale tropical rainfall extremes and their dynamical and thermodynamic modes of change",2017,"10.1002/2017MS001033","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028930026&doi=10.1002%2f2017MS001033&partnerID=40&md5=1aca73ffd89116727c4e553af2304a7a","The Superparameterized Community Atmosphere Model (SPCAM) is used to identify the dynamical and organizational properties of tropical extreme rainfall events on two scales. We compare the mesoscales resolved by General Circulation Models (GCMs) and the convective scales resolved by Cloud-Resolving Models (CRMs) to reassess and extend on previous results from GCMs and CRMs in radiative-convective equilibrium. We first show that the improved representation of subgridscale dynamics in SPCAM allows for a close agreement with the 7%/K Clausius-Clapeyron rate of increase in mesoscale extremes rainfall rates. Three contributions to changes in extremes are quantified and appear consistent in sign and relative magnitude with previous results. On mesoscales, the thermodynamic contribution (5.8%/K) and the contribution from mass flux increases (2%/K) enhance precipitation rates, while the upward displacement of the mass flux profile (-1.1%/K) offsets this increase. Convective-scale extremes behave similarly except that changes in mass flux are negligible due to a balance between greater numbers of strong updrafts and downdrafts and lesser numbers of weak updrafts. Extremes defined on these two scales behave as two independent sets of rainfall events, with different dynamics, geometries, and responses to climate change. In particular, dynamic changes in mesoscale extremes appear primarily sensitive to changes in the large-scale mass flux, while the intensity of convective-scale extremes is not. In particular, the increases in mesoscale mass flux directly contribute to the intensification of mesoscale extreme rain, but do not seem to affect the increase in convective-scale rainfall intensities. These results motivate the need for better understanding the role of the large-scale forcing on the formation and intensification of heavy convective rainfall. © 2017. The Authors."
"36996582600;21735369200;55807354200;55684103400;57212871074;","Climatology of cross-tropopause mass exchange over the Tibetan Plateau and its surroundings",2017,"10.1002/joc.4970","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008496912&doi=10.1002%2fjoc.4970&partnerID=40&md5=55969c31b9507f9bbfbd67b68245c3dc","The cross-tropopause mass flux (CTMF) and long-term trends in stratosphere–troposphere exchange (STE) over the Tibetan Plateau (TP) and its surroundings were analyzed using European Centre for Medium-Range Weather Forecasts reanalysis data. The gross CTMF (the sum of upward and downward mass flux) shows an evident wave train structure over the TP, which is mainly related to the horizontal exchange of air masses along the tropopause associated with the sharp meridional gradient in tropopause pressure or vertical discontinuity of the thermal tropopause in winter. The seasonal cycle of the STE over the TP shows that the gross mass flux is downwards in Northern Hemisphere (NH) winter and upwards in NH summer. The gross CTMF over the TP accounts for 2.96% of the global total CTMF arising from STE processes resolved by Wei method. Both the upward and downward CTMF over the TP exhibit statistically significant positive trends in winter during the period 1979–2009. The strong positive trends of STE in winter over the TP are resulted from the combined effects of the rising tropopause height, enhanced westerlies and decreasing plateau winter monsoon. In summer, both the upward and downward CTMF exhibit statistically significant negative trends over the northern TP, while the trend in upward CTMF is positive over the southern TP, in accordance with the increasing intensity of Asian summer monsoon in recent decades. The sensitivity simulations with a climate model confirm that changes in the Asian monsoon can significantly affect the tropopause and the CTMF over the TP. © 2016 Royal Meteorological Society"
"35733958000;57201366874;57023352700;","A MODIS-based modeling scheme for the estimation of downward surface shortwave radiation under cloud-free conditions",2017,"10.1007/s12517-017-3187-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029597337&doi=10.1007%2fs12517-017-3187-6&partnerID=40&md5=291d432badae2033dce3a0336532212b","Atmospheric aerosol optical depth (AOD) plays an important role in radiation modeling and partly determines the accuracy of estimated downward surface shortwave radiation (DSSR). In this study, Iqbal’s model C was used to estimate DSSR under cloud-free conditions over the Koohin and Chitgar sites in Tehran, Iran; the estimated DSSR was based on (1) our proposed hybrid modeling scheme where the AOD is retrieved using the Simplified Aerosol Retrieval Algorithm (SARA), ground-based measurements at the AERONET site in Zanjan and (2) the AOD from the Terra MODerate-resolution Imaging Spectroradiometer (MODIS) sensor. Several other Terra MODIS land and atmospheric products were also used as input data, including geolocation properties, water vapor, total ozone, surface reflectance, and top-of-atmosphere (TOA) radiance. SARA-based DSSR and MODIS-based DSSR were evaluated with ground-based DSSR measurements at the Koohin and Chitgar sites in 2011 and 2013, respectively; the averaged statistics for SARA-based DSSR [R2 ≈ 0.95, RMSE ≈ 22 W/m2 (2.5% mean value), and bias ≈ 3 W/m2] were stronger than those for MODIS-based DSSR [R2 ≈ 0.79, RMSE ≈ 51 W/m2 (5.8% mean value), and bias ≈ 34 W/m2]. These results show that the proposed hybrid scheme can be used at regional to global scales under the assumption of future access to spatially distributed AERONET sites. Additionally, the robustness of this modeling scheme was exemplified by estimating the aerosol radiative forcing (ARF) during a dust storm in Southwest Asia. The results were comparable to those of previous studies and showed the strength of our modeling scheme. © 2017, The Author(s)."
"7103246957;7004461962;","Analysis of near-surface biases in ERA-Interim over the Canadian Prairies",2017,"10.1002/2017MS001025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029388194&doi=10.1002%2f2017MS001025&partnerID=40&md5=4ad3ebd5c57c64e4d90b2ce17176c21e","We quantify the biases in the diurnal cycle of temperature in ERA-Interim for both warm and cold season using hourly climate station data for four stations in Saskatchewan from 1979 to 2006. The warm season biases increase as opaque cloud cover decreases, and change substantially from April to October. The bias in mean temperature increases almost monotonically from small negative values in April to small positive values in the fall. Under clear skies, the bias in maximum temperature is of the order of −1°C in June and July, and −2°C in spring and fall; while the bias in minimum temperature increases almost monotonically from +1°C in spring to +2.5°C in October. The bias in the diurnal temperature range falls under clear skies from −2.5°C in spring to −5°C in fall. The cold season biases with surface snow have a different structure. The biases in maximum, mean and minimum temperature with a stable BL reach +1°C, +2.6°C and +3°C respectively in January under clear skies. The cold season bias in diurnal range increases from about −1.8°C in the fall to positive values in March. These diurnal biases in 2 m temperature and their seasonal trends are consistent with a high bias in both the diurnal and seasonal amplitude of the model ground heat flux, and a warm season daytime bias resulting from the model fixed leaf area index. Our results can be used as bias corrections in agricultural modeling that use these reanalysis data, and also as a framework for understanding model biases. © 2017. The Authors."
"56449146900;7102745183;","Shallow precipitation detection and classification using multifrequency radar observations and model simulations",2017,"10.1175/JTECH-D-17-0060.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029760650&doi=10.1175%2fJTECH-D-17-0060.1&partnerID=40&md5=70d53039c634a67ebadaee5326b24394","Detection of shallow warm rainfall remains a critical source of uncertainty in remote sensing of precipitation, especially in regions of complex topographic and radiometric transitions, such as mountains and coastlines. To address this problem, a new algorithm to detect and classify shallow rainfall based on space-time dual-frequency correlation (DFC) of concurrent W- and Ka-band radar reflectivity profiles is demonstrated using ground-based observations from the Integrated Precipitation and Hydrology Experiment (IPHEx) in the Appalachian Mountains (MV), United States, and the Biogenic Aerosols-Effects on Clouds and Climate (BAECC) in Hyytiala (TMP), Finland. Detection is successful with false alarm errors of 2.64% and 4.45% for MV and TMP, respectively, corresponding to one order of magnitude improvement over the skill of operational satellite-based radar algorithms in similar conditions. Shallow rainfall is misclassified 12.5% of the time at MV, but all instances of low-level reverse orographic enhancement are detected and classified correctly. The classification errors are 8% and 17% for deep and shallow rainfall, respectively, in TMP; the latter is linked to reflectivity profiles with dark band but insufficient radar sensitivity to light rainfall (&lt; 2 mm h-1) remains the major source of error. The potential utility of the algorithm for satellite-based observations in mountainous regions is explored using an observing system simulation (OSS) of concurrent CloudSat Cloud Profiling Radar (CPR) and GPM Dual-Frequency Precipitation Radar (DPR) during IPHEx, and concurrent satellite observations over Borneo. The results suggest that integration of the methodology in existing regime-based classification algorithms is straightforward, and can lead to significant improvements in the detection and identification of shallow precipitation. © 2017 American Meteorological Society."
"57192700014;57194168711;7404495164;55576700800;55531572100;56973424600;57195760847;57195753778;56898397300;","Estimating high resolution daily air temperature based on remote sensing products and climate reanalysis datasets over glacierized basins: A case study in the Langtang Valley, Nepal",2017,"10.3390/rs9090959","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029753672&doi=10.3390%2frs9090959&partnerID=40&md5=bcd1cbcc65de88dbf29ce588ed227391","Near surface air temperature (Ta) is one of the key input parameters in land surface models and hydrological models as it affects most biogeophysical and biogeochemical processes of the earth surface system. For distributed hydrological modeling over glacierized basins, obtaining high resolution Ta forcing is one of the major challenges. In this study, we proposed a new high resolution daily Ta estimation scheme under both clear and cloudy sky conditions through integrating the moderate-resolution imaging spectroradiometer (MODIS) land surface temperature (LST) and China Meteorological Administration (CMA) land data assimilation system (CLDAS) reanalyzed daily Ta. Spatio-temporal continuous MODIS LST was reconstructed through the data interpolating empirical orthogonal functions (DINEOF) method. Multi-variable regression models were developed at CLDAS scale and then used to estimate Ta at MODIS scale. The new Ta estimation scheme was tested over the Langtang Valley, Nepal as a demonstrating case study. Observations from two automatic weather stations at Kyanging and Yala located in the Langtang Valley from 2012 to 2014 were used to validate the accuracy of Ta estimation. The RMSEs are 2.05, 1.88, and 3.63 K, and the biases are 0.42, -0.68 and -2.86 K for daily maximum, mean and minimum Ta, respectively, at the Kyanging station. At the Yala station, the RMSE values are 4.53, 2.68 and 2.36 K, and biases are 4.03, 1.96 and -0.35 K for the estimated daily maximum, mean and minimum Ta, respectively. Moreover, the proposed scheme can produce reasonable spatial distribution pattern of Ta at the Langtang Valley. Our results show the proposed Ta estimation scheme is promising for integration with distributed hydrological model for glacier melting simulation over glacierized basins. © 2017 by the authors. Licensee MDPI, Basel, Switzerland."
"7402270526;36815906900;7006960661;21743348300;56647601700;57194704067;23011853200;8976516100;","Long-time series aerosol optical depth retrieval from AVHRR data over land in North China and Central Europe",2017,"10.1016/j.rse.2017.06.036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021704952&doi=10.1016%2fj.rse.2017.06.036&partnerID=40&md5=9d13c63654edea0be53ab164b40cd04e","An algorithm for the retrieval of the aerosol optical depth over land (ADL) using radiances at the top of the atmosphere (TOA) measured by the Advanced Very High Resolution Radiometer (AVHRR) is proposed. AVHRR is the only satellite sensor providing nearly continuous global coverage since June 1979, which could generate the longest aerosol climate data records currently available from operational satellites. In the implementation of the ADL algorithm, an analytical model is used which couples an atmospheric radiative transfer model and a land surface reflectance parameterization. The radiation field can be separated into three parts: direct radiance, single-scattered radiance, and multiple-scattered. Each of these parts is individually parameterized. To obtain the surface reflectance in an automatic retrieval procedure over land for AVHRR, the aerosol scattering effect at 3.75 μm was assumed to be negligible and relationships between the surface reflectances at 0.64 μm and 3.75 μm were evaluated for different surface types and the authors propose to use these to obtain the surface reflectance at the shorter wavelength. The 0.64 μm surface reflectance was then used in a radiative transfer model to compute AOD at that wavelength using six different aerosol types, where optimal estimation (OE) theory is applied to minimize the difference between modeled and measured radiances. The ADL algorithm is applied to re-calibrated Level 1B radiances from the AVHRRs on-board the TIROS-N and the Metop-B satellites to retrieve the AOD over North China and Central Europe. The results show that the AOD retrieved from these two instruments are in agreement with co-located AOD values from ground-based reference networks. Over North China, using AERONET sites, 58% of the ADL AOD values are within an expected error (EE) range of ±(0.05 + 20%) and 53% are within the EE range of ±(0.05 + 15%). For GAW-PFR (World Meteorological Organization, WMO, Global Atmosphere Watch, GAW) sites, part of the European ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure) sites, 79% of the ADL AOD values are within the EE range of ±(0.05 + 20%) and 75% are within the EE range of ±(0.05 + 15%). Not surprisingly, the agreement is better over Europe with generally lower AOD values. An additional cross comparison of the AOD results with MODIS (MODerate-resolution Imaging Spectroradiometer) DeepBlue aerosol products shows that the spatial distributions of the two AOD datasets are similar, but with generally lower values for ADL and lower coverage. The temporal variation of the annual mean AOD over selected AERONET sites shows that ADL values are generally between 0.2 and 0.5 over North-Eastern China and trace the MODIS and AERONET data for the overlapping years quite well. © 2016 Elsevier Inc."
"13403622000;","Aerosol Effects on Climate via Mixed-Phase and Ice Clouds",2017,"10.1146/annurev-earth-060115-012240","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029182102&doi=10.1146%2fannurev-earth-060115-012240&partnerID=40&md5=ff99483544cc0fad5c17ef344125ac99","Clouds in Earth's atmosphere can be composed of liquid droplets, ice crystals, or a combination of the two. Clouds' thermodynamic phase is largely controlled by temperature, but other factors can also have a significant effect. Aerosols-i.e., particles suspended in Earth's atmosphere-affect cloud properties differently depending on cloud phase and can potentially have a strong influence on climate via any cloud type. Aerosol-cloud-climate interactions have been a topic of active research for more than two decades, but these interactions nevertheless currently represent one of the most uncertain forcings of climate change over the past century. Most research to date has focused on how aerosols can impact climate via liquid clouds, which are better understood and observed than their ice-containing counterparts. Thus, the problem of how liquid clouds mediate aerosols' effects on climate is a more tractable one. However, there is no a priori reason to think that mixed-phase and ice clouds are any less affected by changes in atmospheric aerosol composition than liquid clouds, and estimates of how aerosols can influence these ice-containing clouds have started to emerge. Laboratory and field work, as well as satellite observations, is now shifting attention to this new frontier in the field of aerosol-cloud-climate interactions, allowing for improved representation of ice processes in numerical models. Here, we review this recent progress in our understanding of aerosol effects on mixed-phase and ice clouds, focusing on the four underpinning research pillars of laboratory experiments, field observations, satellite retrievals, and numerical modeling of global climate. Evident from this review is the possibility of a powerful yet poorly constrained climate forcing, which is uncertain in terms of both its magnitude and its sign. Copyright ©2017 by Annual Reviews. All rights reserved."
"55190871900;57188825789;8876840700;12446001600;6508091526;6505803202;7004342635;","Quantification of cloud water interception in the canopy vegetation from fog gauge measurements",2017,"10.1002/hyp.11228","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026544496&doi=10.1002%2fhyp.11228&partnerID=40&md5=cc888742548603fd89b903ea3241e6d9","With changes in climate looming, quantifying often-overlooked components of the canopy water budget, such as cloud water interception (CWI), is increasingly important. Commonly, CWI quantification requires detailed continuous measurements, which is extremely challenging, especially when throughfall is included. In this study, we propose a simplified approach to estimate CWI using the Rutter-type interception model, where CWI inputs in the canopy vegetation are proportional to fog interception measured by an artificial fog gauge. The model requires the continuous acquisition of meteorological variables as input and calibration datasets. Throughfall measurements below the forest are used only for calibration and validation of the model; thus, CWI estimates can be provided even after the cessation of throughfall monitoring. This approach provides an indirect and undemanding way to quantify CWI by vegetation and allows the identification of its controlling factors, which could be useful to the comparison of CWI in contrasting land covers. The method is applied on a 2-year dataset collected in an endemic highland forest of San Cristobal Island (Galapagos). Our results show that CWI reaches 21% ± 6% of the total water input during the first year, and 9% ± 2% during the second one. These values represent 32% ± 10% and 17% ± 5% of water inputs during the cool foggy season of the first and second year, respectively. The difference between seasons is attributed to a lower fog liquid water during the second season. Copyright © 2017 John Wiley & Sons, Ltd."
"56073532500;7102866124;35461763400;57189372185;13408938100;7004864963;7006790175;7005941217;57190128079;36106033000;57191750766;6602914876;36515307600;57189368623;55942083800;7102084129;7004944088;15926468600;57190209035;","Sensitivities of Amazonian clouds to aerosols and updraft speed",2017,"10.5194/acp-17-10037-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026375000&doi=10.5194%2facp-17-10037-2017&partnerID=40&md5=7141f78cbeb921b80c38c61535db510f","The effects of aerosol particles and updraft speed on warm-phase cloud microphysical properties are studied in the Amazon region as part of the ACRIDICON-CHUVA experiment. Here we expand the sensitivity analysis usually found in the literature by concomitantly considering cloud evolution, putting the sensitivity quantifications into perspective in relation to in-cloud processing, and by considering the effects on droplet size distribution (DSD) shape. Our in situ aircraft measurements over the Amazon Basin cover a wide range of particle concentration and thermodynamic conditions, from the pristine regions over coastal and forested areas to the southern Amazon, which is highly polluted from biomass burning. The quantitative results show that particle concentration is the primary driver for the vertical profiles of effective diameter and droplet concentration in the warm phase of Amazonian convective clouds, while updraft speeds have a modulating role in the latter and in total condensed water. The cloud microphysical properties were found to be highly variable with altitude above cloud base, which we used as a proxy for cloud evolution since it is a measure of the time droplets that were subject to cloud processing. We show that DSD shape is crucial in understanding cloud sensitivities. The aerosol effect on DSD shape was found to vary with altitude, which can help models to better constrain the indirect aerosol effect on climate. © 2017 Author(s)."
"57195470495;6701519241;6603566335;","The spatial extent of rainfall events and its relation to precipitation scaling",2017,"10.1002/2017GL074857","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028347417&doi=10.1002%2f2017GL074857&partnerID=40&md5=c65c091e1f7b7f61b77c154c31d72acb","Observations show that subdaily precipitation extremes increase with dew point temperature at a rate exceeding the Clausius-Clapeyron (CC) relation. The understanding of this so-called super CC scaling is still incomplete, and observations of convective cell properties could provide important information. Here the size and intensity of rain cells are investigated by using a tracking of rainfall events in high-resolution radar data. Higher intensities are accompanied by larger rainfall areas. However, whereas small rain cells mainly follow CC scaling, larger cells display super CC behavior. Even more, for dew point exceeding 15°C, the rain cell size has to increase in order to sustain super CC scaling and a remarked increase in rain cell area is found. Our results imply that the source area of moisture, the cloud size, and the degree of mesoscale organization play key roles in the context of a warming climate. ©2017. American Geophysical Union. All Rights Reserved."
"56763174500;55745955800;7401936984;","Investigating the dependence of SCM simulated precipitation and clouds on the spatial scale of large-scale forcing at SGP",2017,"10.1002/2017JD026565","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029311509&doi=10.1002%2f2017JD026565&partnerID=40&md5=5f1e06fa5ec15ecb4ef7441a3b0590e3","Large-scale forcing data, such as vertical velocity and advective tendencies, are required to drive single-column models (SCMs), cloud-resolving models, and large-eddy simulations. Previous studies suggest that some errors of these model simulations could be attributed to the lack of spatial variability in the specified domain-mean large-scale forcing. This study investigates the spatial variability of the forcing and explores its impact on SCM simulated precipitation and clouds. A gridded large-scale forcing data during the March 2000 Cloud Intensive Operational Period at the Atmospheric Radiation Measurement program's Southern Great Plains site is used for analysis and to drive the single-column version of the Community Atmospheric Model Version 5 (SCAM5). When the gridded forcing data show large spatial variability, such as during a frontal passage, SCAM5 with the domain-mean forcing is not able to capture the convective systems that are partly located in the domain or that only occupy part of the domain. This problem has been largely reduced by using the gridded forcing data, which allows running SCAM5 in each subcolumn and then averaging the results within the domain. This is because the subcolumns have a better chance to capture the timing of the frontal propagation and the small-scale systems. Other potential uses of the gridded forcing data, such as understanding and testing scale-aware parameterizations, are also discussed. ©2017. The Authors."
"55960948400;8919299300;7006145109;","The impact of aerosol vertical distribution on aerosol optical depth retrieval using CALIPSO and MODIS data: Case study over dust and smoke regions",2017,"10.1002/2016JD026355","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029288520&doi=10.1002%2f2016JD026355&partnerID=40&md5=03f8abbc22d80f4aa771e6facd3795a0","Global quantitative aerosol information has been derived from MODerate Resolution Imaging SpectroRadiometer (MODIS) observations for decades since early 2000 and widely used for air quality and climate change research. However, the operational MODIS Aerosol Optical Depth (AOD) products Collection 6 (C6) can still be biased, because of uncertainty in assumed aerosol optical properties and aerosol vertical distribution. This study investigates the impact of aerosol vertical distribution on the AOD retrieval. We developed a new algorithm by considering dynamic vertical profiles, which is an adaptation of MODIS C6 Dark Target (C6_DT) algorithm over land. The new algorithm makes use of the aerosol vertical profile extracted from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) measurements to generate an accurate top of the atmosphere (TOA) reflectance for the AOD retrieval, where the profile is assumed to be a single layer and represented as a Gaussian function with the mean height as single variable. To test the impact, a comparison was made between MODIS DT and Aerosol Robotic Network (AERONET) AOD, over dust and smoke regions. The results show that the aerosol vertical distribution has a strong impact on the AOD retrieval. The assumed aerosol layers close to the ground can negatively bias the retrievals in C6_DT. Regarding the evaluated smoke and dust layers, the new algorithm can improve the retrieval by reducing the negative biases by 3–5%. ©2017. American Geophysical Union. All Rights Reserved."
"57189377456;7403401100;55915364000;23668415500;57189358333;7102084129;8657171200;54279446400;10739566100;7006708207;7202252296;","Top-down and bottom-up aerosol-cloud closure: Towards understanding sources of uncertainty in deriving cloud shortwave radiative flux",2017,"10.5194/acp-17-9797-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028090604&doi=10.5194%2facp-17-9797-2017&partnerID=40&md5=b2dd123a44508f4fed49c90fe8e5fa11","Top-down and bottom-up aerosol-cloud shortwave radiative flux closures were conducted at the Mace Head Atmospheric Research Station in Galway, Ireland, in August 2015. This study is part of the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) European collaborative project, with the goal of understanding key processes affecting aerosol-cloud shortwave radiative flux closures to improve future climate predictions and develop sustainable policies for Europe. Instrument platforms include ground-based unmanned aerial vehicles (UAVs)1 and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1-D microphysical aerosol-cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction or a five-hole probe for 3-D wind vectors. UAV cloud measurements are rare and have only become possible in recent years through the miniaturization of instrumentation. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF) by between 25 and 60gWgm-2. After accounting for entrainment, satellite-derived cloud droplet number concentrations (CDNCs) were within 30g% of simulated CDNC. In cases with a well-mixed boundary layer, δRF is no greater than 20gWgm-2 after accounting for cloud-top entrainment and up to 50gWm-2 when entrainment is not taken into account. In cases with a decoupled boundary layer, cloud microphysical properties are inconsistent with ground-based aerosol measurements, as expected, and δRF is as high as 88gWm-2, even high (>30Wm-2) after accounting for cloud-top entrainment. This work demonstrates the need to take in situ measurements of aerosol properties for cases where the boundary layer is decoupled as well as consider cloud-top entrainment to accurately model stratocumulus cloud radiative flux. © Author(s) 2017."
"57155942300;7006328089;","Atmospheric circulation and hydroclimate impacts of alternative warming scenarios for the Eocene",2017,"10.5194/cp-13-1037-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027562648&doi=10.5194%2fcp-13-1037-2017&partnerID=40&md5=2531f4505893511795be53ac878f2cfa","Recent work in modelling the warm climates of the early Eocene shows that it is possible to obtain a reasonable global match between model surface temperature and proxy reconstructions, but only by using extremely high atmospheric CO2 concentrations or more modest CO2 levels complemented by a reduction in global cloud albedo. Understanding the mix of radiative forcing that gave rise to Eocene warmth has important implications for constraining Earth's climate sensitivity, but progress in this direction is hampered by the lack of direct proxy constraints on cloud properties. Here, we explore the potential for distinguishing among different radiative forcing scenarios via their impact on regional climate changes. We do this by comparing climate model simulations of two end-member scenarios: one in which the climate is warmed entirely by CO2 (which we refer to as the greenhouse gas (GHG) scenario) and another in which it is warmed entirely by reduced cloud albedo (which we refer to as the q low CO2-thin clouds/q or LCTC scenario) . The two simulations have an almost identical global-mean surface temperature and equator-to-pole temperature difference, but the LCTC scenario has g 1/4 g 11g % greater global-mean precipitation than the GHG scenario. The LCTC scenario also has cooler midlatitude continents and warmer oceans than the GHG scenario and a tropical climate which is significantly more El Niño-like. Extremely high warm-season temperatures in the subtropics are mitigated in the LCTC scenario, while cool-season temperatures are lower at all latitudes. These changes appear large enough to motivate further, more detailed study using other climate models and a more realistic set of modelling assumptions. © Author(s) 2017."
"57204074114;57193261410;43761634800;","Density Functional Theory Calculation of the Absorption Properties of Brown Carbon Chromophores Generated by Catechol Heterogeneous Ozonolysis",2017,"10.1021/acsearthspacechem.7b00061","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054403828&doi=10.1021%2facsearthspacechem.7b00061&partnerID=40&md5=ac60037afe3f17aeb3cbb4dd8b38953a","The effect of light-absorbing atmospheric particles on climate change has been incorporated into climate models, but the absence of brown carbon (BrC) in these models has been leading to significant differences between model predictions and measured data on radiative forcing. Also, little is known regarding the relationship between optical properties and chemical compositions of BrC. Thus, we have characterized the absorption properties of catechol and known heterogeneous ozonolysis products, with a theoretical approach based on density functional theory (DFT). While catechol presents a weak absorption maximum in the ultraviolet C (UVC) region, other polyaromatic derivatives present an absorption up to 6 times higher, with biphenyl-2,2′,3,3′-tetraol, biphenyl-3,3′,4,4′,5,5′-hexaol, and terphenyl-2′,3,3′,3″,4,4″-hexaol presenting the strongest absorption. Moreover, these derivatives now absorb in the ultraviolet B (UVB) and ultraviolet A (UVA) regions, which are types of actinic radiation in the ultraviolet (UV) region not filtered by atmosphere (contrary to UVC), with terphenyl molecules presenting the highest absorption maximum. Furthermore, the absorption efficiency of these compounds is potentiated in the condensed phase, such as cloud droplets, rain, fog, and water films, as a result of a higher degree of electron delocalization. This study provides reliable information regarding the absorption properties of BrC generated by catechol, which is essential for the development of accurate models of climate forcing. © 2017 American Chemical Society."
"57202142004;36160514000;6602589744;56592889000;7102432271;36239869400;16444949400;6602352339;7004347243;57193213111;7006577245;57208121047;8570871900;7006686129;","Quantifying black carbon deposition over the Greenland ice sheet from forest fires in Canada",2017,"10.1002/2017GL073701","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026767232&doi=10.1002%2f2017GL073701&partnerID=40&md5=0d8684e12cdbcc14f6839d635dd1757d","Black carbon (BC) concentrations observed in 22 snowpits sampled in the northwest sector of the Greenland ice sheet in April 2014 have allowed us to identify a strong and widespread BC aerosol deposition event, which was dated to have accumulated in the pits from two snow storms between 27 July and 2 August 2013. This event comprises a significant portion (57% on average across all pits) of total BC deposition over 10 months (July 2013 to April 2014). Here we link this deposition event to forest fires burning in Canada during summer 2013 using modeling and remote sensing tools. Aerosols were detected by both the Cloud-Aerosol Lidar with Orthogonal Polarization (on board CALIPSO) and Moderate Resolution Imaging Spectroradiometer (Aqua) instruments during transport between Canada and Greenland. We use high-resolution regional chemical transport modeling (WRF-Chem) combined with high-resolution fire emissions (FINNv1.5) to study aerosol emissions, transport, and deposition during this event. The model captures the timing of the BC deposition event and shows that fires in Canada were the main source of deposited BC. However, the model underpredicts BC deposition compared to measurements at all sites by a factor of 2–100. Underprediction of modeled BC deposition originates from uncertainties in fire emissions and model treatment of wet removal of aerosols. Improvements in model descriptions of precipitation scavenging and emissions from wildfires are needed to correctly predict deposition, which is critical for determining the climate impacts of aerosols that originate from fires. ©2017. American Geophysical Union. All Rights Reserved."
"26643250500;7004944088;","Susceptibility of contrail ice crystal numbers to aircraft soot particle emissions",2017,"10.1002/2017GL074949","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028436115&doi=10.1002%2f2017GL074949&partnerID=40&md5=bab1791cd6dc207817ea48fe507786ab","We develop an idealized, physically based model describing combined effects of ice nucleation and sublimation on ice crystal number during persistent contrail formation. Our study represents the first effort to predict ice numbers at the point where contrails transition into contrail cirrus—several minutes past formation—by connecting them to aircraft soot particle emissions and atmospheric supersaturation with respect to ice. Results averaged over an observed exponential distribution of ice supersaturation (mean value 15%) indicate that large reductions in soot particle numbers are needed to lower contrail ice crystal numbers significantly for soot emission indices around 1015 (kg fuel)−1, because reductions in nucleated ice number are partially compensated by sublimation losses. Variations in soot particle (−50%) and water vapor (+10%) emission indices at threefold lower soot emissions resulting from biofuel blending cause ice crystal numbers to change by −35% and &lt;5%, respectively. The efficiency of reduction depends on ice supersaturation and the size distribution of nucleated ice crystals in jet exhaust plumes and on atmospheric ice supersaturation, making the latter another key factor in contrail mitigation. We expect our study to have important repercussions for planning airborne measurements targeting contrail formation, designing parameterization schemes for use in large-scale models, reducing uncertainties in predicting contrail cirrus, and mitigating the climate impact of aviation. ©2017. American Geophysical Union. All Rights Reserved."
"55938109300;57192915106;7006770362;54941580100;12544502800;55879681300;13007286600;55807448700;24767977600;22635720500;7003862871;24333054700;6505947323;7004020627;56652332900;39361670300;","Regional effects of atmospheric aerosols on temperature: An evaluation of an ensemble of online coupled models",2017,"10.5194/acp-17-9677-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027340999&doi=10.5194%2facp-17-9677-2017&partnerID=40&md5=3397a4f37503e5f2d559250e76f81993","The climate effect of atmospheric aerosols is associated with their influence on the radiative budget of the Earth due to the direct aerosol-radiation interactions (ARIs) and indirect effects, resulting from aerosol-cloud-radiation interactions (ACIs). Online coupled meteorology-chemistry models permit the description of these effects on the basis of simulated atmospheric aerosol concentrations, although there is still some uncertainty associated with the use of these models. Thus, the objective of this work is to assess whether the inclusion of atmospheric aerosol radiative feedbacks of an ensemble of online coupled models improves the simulation results for maximum, mean and minimum temperature at 2m over Europe. The evaluated models outputs originate from EuMetChem COST Action ES1004 simulations for Europe, differing in the inclusion (or omission) of ARI and ACI in the various models. The cases studies cover two important atmospheric aerosol episodes over Europe in the year 2010: (i) a heat wave event and a forest fire episode (July-August 2010) and (ii) a more humid episode including a Saharan desert dust outbreak in October 2010. The simulation results are evaluated against observational data from the E-OBS gridded database. The results indicate that, although there is only a slight improvement in the bias of the simulation results when including the radiative feedbacks, the spatiotemporal variability and correlation coefficients are improved for the cases under study when atmospheric aerosol radiative effects are included."
"57189634238;56931957400;20435752700;42361233000;56193650100;57189631668;","How do changes in warm-phase microphysics affect deep convective clouds?",2017,"10.5194/acp-17-9585-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027139940&doi=10.5194%2facp-17-9585-2017&partnerID=40&md5=7018574bf848728792326d2a706795c8","Understanding aerosol effects on deep convective clouds and the derived effects on the radiation budget and rain patterns can largely contribute to estimations of climate uncertainties. The challenge is difficult in part because key microphysical processes in the mixed and cold phases are still not well understood. For deep convective clouds with a warm base, understanding aerosol effects on the warm processes is extremely important as they set the initial and boundary conditions for the cold processes. Therefore, the focus of this study is the warm phase, which can be better resolved. The main question is: ""How do aerosol-derived changes in the warm phase affect the properties of deep convective cloud systems?"" To explore this question, we used a weather research and forecasting (WRF) model with spectral bin microphysics to simulate a deep convective cloud system over the Marshall Islands during the Kwajalein Experiment (KWAJEX). The model results were validated against observations, showing similarities in the vertical profile of radar reflectivity and the surface rain rate. Simulations with larger aerosol loading resulted in a larger total cloud mass, a larger cloud fraction in the upper levels, and a larger frequency of strong updrafts and rain rates. Enlarged mass both below and above the zero temperature level (ZTL) contributed to the increase in cloud total mass (water and ice) in the polluted runs. Increased condensation efficiency of cloud droplets governed the gain in mass below the ZTL, while both enhanced condensational and depositional growth led to increased mass above it. The enhanced mass loading above the ZTL acted to reduce the cloud buoyancy, while the thermal buoyancy (driven by the enhanced latent heat release) increased in the polluted runs. The overall effect showed an increased upward transport (across the ZTL) of liquid water driven by both larger updrafts and larger droplet mobility. These aerosol effects were reflected in the larger ratio between the masses located above and below the ZTL in the polluted runs. When comparing the net mass flux crossing the ZTL in the clean and polluted runs, the difference was small. However, when comparing the upward and downward fluxes separately, the increase in aerosol concentration was seen to dramatically increase the fluxes in both directions, indicating the aerosol amplification effect of the convection and the affected cloud system properties, such as cloud fraction and rain rate. © 2017 Author(s)."
"56531367400;55628589750;56735478500;15071907100;57203053317;","Understanding the drivers of marine liquid-water cloud occurrence and properties with global observations using neural networks",2017,"10.5194/acp-17-9535-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027217508&doi=10.5194%2facp-17-9535-2017&partnerID=40&md5=58863096bffbd0ae426068af5449bf78","The role of aerosols, clouds and their interactions with radiation remain among the largest unknowns in the climate system. Even though the processes involved are complex, aerosol-cloud interactions are often analyzed by means of bivariate relationships. In this study, 15 years (2001-2015) of monthly satellite-retrieved near-global aerosol products are combined with reanalysis data of various meteorological parameters to predict satellite-derived marine liquid-water cloud occurrence and properties by means of region-specific artificial neural networks. The statistical models used are shown to be capable of predicting clouds, especially in regions of high cloud variability. On this monthly scale, lower-tropospheric stability is shown to be the main determinant of cloud fraction and droplet size, especially in stratocumulus regions, while boundary layer height controls the liquid-water amount and thus the optical thickness of clouds. While aerosols show the expected impact on clouds, at this scale they are less relevant than some meteorological factors. Global patterns of the derived sensitivities point to regional characteristics of aerosol and cloud processes. © 2017 Author(s)."
"55827276200;16403404400;36161161900;6602543142;12139043600;12139310900;7004365480;24335169200;","Amplification of global warming through pH dependence of DMS production simulated with a fully coupled Earth system model",2017,"10.5194/bg-14-3633-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027265744&doi=10.5194%2fbg-14-3633-2017&partnerID=40&md5=a28d02ddd1d72013ae8011a87971563f","We estimate the additional transient surface warming ΔTs caused by a potential reduction of marine dimethyl sulfide (DMS) production due to ocean acidification under the high-emission scenario RCP8.5 until the year 2200. Since we use a fully coupled Earth system model, our results include a range of feedbacks, such as the response of marine DMS production to the additional changes in temperature and sea ice cover. Our results are broadly consistent with the findings of a previous study that employed an offline model set-up. Assuming a medium (strong) sensitivity of DMS production to pH, we find an additional transient global warming of 0.30 K (0.47 K) towards the end of the 22nd century when DMS emissions are reduced by 7.3 Tg S yr-1 or 31 % (11.5 Tg S yr-1 or 48 %). The main mechanism behind the additional warming is a reduction of cloud albedo, but a change in shortwave radiative fluxes under clear-sky conditions due to reduced sulfate aerosol load also contributes significantly. We find an approximately linear relationship between reduction of DMS emissions and changes in top of the atmosphere radiative fluxes as well as changes in surface temperature for the range of DMS emissions considered here. For example, global average Ts changes by -0. 041 K per 1 Tg S yr-1 change in sea-air DMS fluxes. The additional warming in our model has a pronounced asymmetry between northern and southern high latitudes. It is largest over the Antarctic continent, where the additional temperature increase of 0.56 K (0.89 K) is almost twice the global average. We find that feedbacks are small on the global scale due to opposing regional contributions. The most pronounced feedback is found for the Southern Ocean, where we estimate that the additional climate change enhances sea-air DMS fluxes by about 9 % (15 %), which counteracts the reduction due to ocean acidification. © Author(s) 2017."
"7005354212;22234180300;57197754464;","Quantitatively assessing cloud cover fraction in numerical weather prediction and climate models",2017,"10.1080/2150704X.2017.1317932","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034587915&doi=10.1080%2f2150704X.2017.1317932&partnerID=40&md5=5309a7f2face99442a92bbb35725e0d1","Procedures are presented that exploit remotely-sensed satellite cloud data products to quantitatively assess the accuracy of cloud cover fraction (CCf) in datasets generated by numerical weather prediction (NWP) and climate models. These procedures are demonstrated with analyses created from the North American Mesoscale (NAM) Forecast System and forecasts generated with the WRF (Weather Research and Forecast) model. First VIIRS (Visible Infrared Imager Radiometry Suite) cloud data products are collocated within NAM gridded fields to identify grid cells for comparison against manually-generated cloud masks that are based upon VIIRS imagery and serve to characterize the accuracy of CCf fields in the NAM datasets. Next, short-range CCf forecasts are generated from these NAM datasets with the WRF model and the results are again compared to the manually-generated cloud mask datasets. Comparisons between the NAMCCf products and those in the manually-generated CCf fields reveal a systematic bias toward under-clouding in the NAM analyses which are important to cloud forecasts for air quality and solar energy applications as well as climate modeling. Poorer correlations were found in comparisons between the WRF cloud forecasts and the manually-generated CCf fields. © 2017 Informa UK Limited."
"55349680000;7003854772;","Estimating the Great Lakes net radiation using satellite remote sensing and MERRA reanalysis",2017,"10.1080/17538947.2016.1252432","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021742123&doi=10.1080%2f17538947.2016.1252432&partnerID=40&md5=1f5964bdc2f3decd00fd37a2fb0d89a4","The net all-wave radiation of the Great Lakes (GL) is a key to understanding the effects of climate change on the GL. There is a high possibility of underestimating the net all-wave radiation of the GL when using existing methodologies with inputs from near-shore and land-based meteorological data. This study provides the first technique to estimate net all-wave radiation over the GL from July 2001 to December 2014 using a combination of data from satellite remote sensing, reanalysis data sets, and direct measurements. The components of the surface radiation budget estimated from the proposed method showed good statistical agreement. The instantaneous net radiation estimated by our methods was compared with the in situ measurements from June 2008 to April 2012 (Stannard Rock Lighthouse: SR) and September 2009–April 2011 (Spectacle Reef Lighthouse: SP). The comparisons from SR and SP also showed strong statistic agreement (R2 = 0.74 and 0.7; RMSE = 9.26 and 10.60 W m−2 respectively). Monthly spatial variations of net shortwave radiation varied with cloud cover and surface albedo while net longwave radiation varied with the temperature difference between the water surface and the atmosphere. © 2016 Informa UK Limited, trading as Taylor & Francis Group."
"56250276800;6507427481;52463191200;14523614100;56313933300;","Reproduction of spatio-temporal patterns of major mediterranean phytoplankton groups from remote sensing OC-CCI data",2017,"10.3389/fmars.2017.00246","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027170974&doi=10.3389%2ffmars.2017.00246&partnerID=40&md5=5106538a96bfa645c5a1b29ace8825b1","During the last two decades, several satellite algorithms have been proposed to retrieve information about phytoplankton groups using ocean color data. One of these algorithms, the so-called PHYSAT-Med, was developed specifically for the Mediterranean Sea due to the optical peculiarities of this basin. The method allows the detection from ocean color images of the dominant Mediterranean phytoplankton groups, namely nanoeukaryotes, Prochlorococcus, Synechococcus, diatoms, coccolithophorids, and Phaeocystis-like phytoplankton. Here, we present a new version of PHYSAT-Med applied to the Ocean Colour-Climate Change Initiative (OC-CCI) database. The OC-CCI database consists of a multi-sensor, global ocean-color product that merges observations from four different sensors. This retuned version presents improvements with respect to the previous version, as it increases the temporal range (since 1998), decreases the cloud cover, improves the bias correction and a validation exercise was performed in the NW Mediterranean Sea. In particular, the PHYSAT-Med version has been used here to analyse the annual cycles of the major phytoplankton groups in the Mediterranean Sea. Wavelet analyses were used to explore the spatial variability in dominance both in the time and frequency domains in several Mediterranean sub-regions, such as the Alboran Sea, Ligurian Sea, Northern Adriatic Sea, and Levantine basin. Results extended the interpretation of previously detected patterns, indicating the dominance of Synechococcus-like vs. prochlorophytes throughout the year at the basin level, and the predominance of nanoeukaryotes during the winter months. The method successfully reproduced the diatom blooms normally detected in the basin during the spring season (March to April), especially in the Adriatic Sea. According to our results, the PHYSAT-Med OC-CCI algorithm represents a useful tool for the spatio-temporal monitoring of dominant phytoplankton groups in Mediterranean surface waters. The successful applications of other regional ocean color algorithms to the OC-CCI database will give rise to extended time series of phytoplankton functional types, with promising applications to the study of long-term oceanographic trends in a global change context. © 2017 Navarro, Almaraz, Caballero, Vázquez and Huertas."
"36183647300;7402064802;22635190100;36856321600;7005920812;25031430500;6506848305;","A cloudy planetary boundary layer oscillation arising from the coupling of turbulence with precipitation in climate simulations",2017,"10.1002/2017MS000993","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029396832&doi=10.1002%2f2017MS000993&partnerID=40&md5=f85a4317d5cf3d8fd5022e03180977a4","The Community Atmosphere Model (CAM) adopts Cloud Layers Unified By Binormals (CLUBB) scheme and an updated microphysics (MG2) scheme for a more unified treatment of cloud processes. This makes interactions between parameterizations tighter and more explicit. In this study, a cloudy planetary boundary layer (PBL) oscillation related to interaction between CLUBB and MG2 is identified in CAM. This highlights the need for consistency between the coupled subgrid processes in climate model development. This oscillation occurs most often in the marine cumulus cloud regime. The oscillation occurs only if the modeled PBL is strongly decoupled and precipitation evaporates below the cloud. Two aspects of the parameterized coupling assumptions between CLUBB and MG2 schemes cause the oscillation: (1) a parameterized relationship between rain evaporation and CLUBB's subgrid spatial variance of moisture and heat that induces an extra cooling in the lower PBL and (2) rain evaporation which happens at a too low an altitude because of the precipitation fraction parameterization in MG2. Either one of these two conditions can overly stabilize the PBL and reduce the upward moisture transport to the cloud layer so that the PBL collapses. Global simulations prove that turning off the evaporation-variance coupling and improving the precipitation fraction parameterization effectively reduces the cloudy PBL oscillation in marine cumulus clouds. By evaluating the causes of the oscillation in CAM, we have identified the PBL processes that should be examined in models having similar oscillations. This study may draw the attention of the modeling and observational communities to the issue of coupling between parameterized physical processes. © 2017. The Authors."
"7202733689;7003543851;","Hemispheric climate shifts driven by anthropogenic aerosol-cloud interactions",2017,"10.1038/NGEO2988","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026633666&doi=10.1038%2fNGEO2988&partnerID=40&md5=bcba428997f518993831d3f7e21f5da3","The contrasting rainfall between the wet tropics and the dry subtropics largely determines the climate of the tropical zones. A southward shift of these rain belts has been observed throughout the latter half of the twentieth century, with profound societal consequences. Although such large-scale shifts in rainfall have been linked to interhemispheric temperature gradients from anthropogenic aerosols, a complete understanding of this mechanism has been hindered by the lack of explicit information on aerosol radiative effects. Here we quantify the relative contributions of radiative forcing from anthropogenic aerosols to the interhemispheric asymmetry in temperature and precipitation change for climate change simulations.We show that in model simulations the vast majority of the precipitation shift does not result from aerosols directly through their absorption and scattering of radiation, but rather indirectly through their modification of cloud radiative properties. Models with larger cloud responses to aerosol forcing are found to better reproduce the observed interhemispheric temperature changes and tropical rain belt shifts over the twentieth century, suggesting that aerosol-cloud interactions will play a key role in determining future interhemispheric shifts in climate. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved."
"56509504400;6507785309;","Closed-form analytic solution of cloud dissipation for a mixed-layer model",2017,"10.1175/JAS-D-16-0303.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027410368&doi=10.1175%2fJAS-D-16-0303.1&partnerID=40&md5=c9552ebe4cf298050e527112f11faa9e","Stratocumulus clouds play an important role in climate cooling and are hard to predict using global climate and weather forecast models. Thus, previous studies in the literature use observations and numerical simulation tools, such as large-eddy simulation (LES), to solve the governing equations for the evolution of stratocumulus clouds. In contrast to the previous works, this work provides an analytic closed-form solution to the cloud thickness evolution of stratocumulus clouds in a mixed-layer model framework. With a focus on application over coastal lands, the diurnal cycle of cloud thickness and whether or not clouds dissipate are of particular interest. An analytic solution enables the sensitivity analysis of implicitly interdependent variables and extrema analysis of cloud variables that are hard to achieve using numerical solutions. In this work, the sensitivity of inversion height, cloud-base height, and cloud thickness with respect to initial and boundary conditions, such as Bowen ratio, subsidence, surface temperature, and initial inversion height, are studied. A critical initial cloud thickness value that can be dissipated pre- and postsunrise is provided. Furthermore, an extrema analysis is provided to obtain the minima and maxima of the inversion height and cloud thickness within 24 h. The proposed solution is validated against LES results under the same initial and boundary conditions. © 2017 American Meteorological Society."
"35490341500;9536598800;8942525300;","Observations of increased cloud cover over irrigated agriculture in an arid environment",2017,"10.1175/JHM-D-16-0208.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027987274&doi=10.1175%2fJHM-D-16-0208.1&partnerID=40&md5=c8fc19190522ad9fd1319cdad9081cd2","Irrigated agriculture accounts for 20% of global cropland area and may alter climate locally and globally, but feedbacks on clouds and rainfall remain highly uncertain, particularly in arid regions. Nonrenewable groundwater in arid regions accounts for 20% of global irrigation water demand, and quantifying these feedbacks is crucial for the prediction of long-term water use in a changing climate. Here, satellite data are used to show how irrigated crops in an arid environment alter land surface properties, cloud cover, and rainfall patterns. Land surface temperatures (LSTs) over the cropland are 5-7 K lower than their surroundings, despite a lower albedo, suggesting that Bowen ratio is strongly reduced (and latent heat fluxes increased) over the irrigated cropland. Daytime cloud cover is increased by up to 15% points (a relative increase of 60%), with increased cloud development in the morning and a greater afternoon peak in cloud. Cloud cover is significantly correlated with interannual variations in vegetation and LST. Afternoon rainfall also appears to be enhanced around the irrigation. The cloud feedback is the opposite of what has been previously observed in tropical and semiarid regions, suggesting different processes drive land-atmosphere feedbacks in very dry environments. Increased cloud and rainfall, and associated increases in diffuse radiation and reductions in temperature, are likely to benefit vegetation growth. Predictions of changes in crop productivity due to climate change and the impacts of global land-use change on climate and the use of water resources would therefore benefit from including these effects. © 2017 American Meteorological Society."
"6602926744;56638409500;55464772600;56697819500;8103333100;7003361863;7201507999;54082897100;7005922032;57110076500;35219971000;7003430681;57203404677;6505874293;7403247998;","Development of the Regional Arctic System Model (RASM): Near-surface atmospheric climate sensitivity",2017,"10.1175/JCLI-D-15-0775.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020113148&doi=10.1175%2fJCLI-D-15-0775.1&partnerID=40&md5=6d978ca6914f07a34a3ea03474eb20ad","The near-surface climate, including the atmosphere, ocean, sea ice, and land state and fluxes, in the initial version of the Regional Arctic System Model (RASM) are presented. The sensitivity of the RASM near-surface climate to changes in atmosphere, ocean, and sea ice parameters and physics is evaluated in four simulations. The near-surface atmospheric circulation is well simulated in all four RASM simulations but biases in surface temperature are caused by biases in downward surface radiative fluxes. Errors in radiative fluxes are due to biases in simulated clouds with different versions of RASM simulating either too much or too little cloud radiative impact over open ocean regions and all versions simulating too little cloud radiative impact over land areas. Cold surface temperature biases in the central Arctic in winter are likely due to too few or too radiatively thin clouds. The precipitation simulated by RASM is sensitive to changes in evaporation that were linked to sea surface temperature biases. Future work will explore changes in model microphysics aimed at minimizing the cloud and radiation biases identified in this work. © 2017 American Meteorological Society."
"57194798352;7006387943;25924878400;","Evaluation of cloud liquid water path trends using a multidecadal record of passive microwave observations",2017,"10.1175/JCLI-D-16-0399.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022324589&doi=10.1175%2fJCLI-D-16-0399.1&partnerID=40&md5=ce771d06aca26972dec036a5aff4a30b","In this study, observed cloud liquid water path (LWP) trends from the Multisensor Advanced Climatology of Liquid Water Path (MAC-LWP) dataset (1988-2014) are compared to trends computed from the temporally coincident records of 16 global climate models (GCMs) participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5). For many regions, observed trend magnitudes are several times larger than the corresponding model mean trend magnitudes. Muted model mean trends are thought to be the result of cancellation effects arising from differing interannual variability characteristics and differences in model physics-dynamics. In most regions, the majority of modeled trends were statistically consistent with the observed trends. This was thought to be because of large estimated errors in both the observations and the models due to interannual variability. Over the southern oceans (south of 408S latitude), general agreement between the observed trend and virtually allGCMtrends is also found (about 1-2 gm-2 decade-1). Observed trends are also compared to those from the Atmospheric Model Intercomparison Project (AMIP). Like the CMIP5 models, the majority of modeled AMIPtrends were statistically consistent with the observed trends. It was also found that, in regions where the AMIP model mean time series better captures observed interannual variability, it tends to better capture the magnitude of the observed trends. © 2017 American Meteorological Society."
"56447586200;55745955800;","The role of shallow convection over the Tibetan Plateau",2017,"10.1175/JCLI-D-16-0599.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022338889&doi=10.1175%2fJCLI-D-16-0599.1&partnerID=40&md5=29e5f037eb6736de5339a9b88da41620","Cumulus (Cu) from shallow convection is one of the dominant cloud types over the Tibetan Plateau (TP) in the summer according to CloudSat-CALIPSO observations. Its thermodynamic effects on the atmospheric environment and impacts on the large-scale atmospheric circulation are studied in this paper using the Community Atmospheric Model, version 5.3 (CAM5.3). It is found that the model can reasonably simulate the unique distribution of diabatic heating and Cu over the TP. Shallow convection provides the dominant diabatic heating and drying to the lower and middle atmosphere over the TP. A sensitivity experiment indicates that without Cu over the TP, large-scale condensation and stratiform clouds would increase dramatically, which induces enhanced low-level wind and moisture convergence toward the TP, resulting in significantly enhanced monsoon circulation with remote impact on the areas far beyond the TP. Cu therefore acts as a safety valve to modulate the atmospheric environment that prevents the formation of superclusters of stratiform clouds and precipitation over the TP. © 2017 American Meteorological Society."
"57193884115;6603109490;","Investigation of aerosol effects on the Arctic surface temperature during the diurnal cycle: part 1 – total aerosol effect",2017,"10.1002/joc.5036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017355348&doi=10.1002%2fjoc.5036&partnerID=40&md5=ffbcfab58924fbe47f631e6f75f4bbea","Temperature changes in the Arctic due to anthropogenic climate change are larger in magnitude than those at lower latitudes, with sea ice extent and thickness diminishing since the dawn of the satellite era. Aerosols may play a vital role in determining these changes, as the radiation reaching the Arctic surface is impacted directly by aerosol absorption and scattering, as well as the ability of aerosols to act as cloud condensation nuclei (CCN) and ice nuclei (IN). This study uses the Weather Research and Forecasting Chemistry (WRF-Chem) model to show the impact of aerosol absorption, scattering, and CCN contribution on the Arctic surface, with a particular focus on how these effects change throughout the diurnal cycle. Part 1 of this two-part study investigates the changes in surface temperature, radiation, and cloud properties due to the total aerosol effect in the Arctic. A suite of ensemble runs is used to develop a filtering mechanism based upon the t-test to eliminate the effects of meteorological variability. While much has been speculated about the cooling role of aerosols, this study shows that aerosols have both a warming and cooling effect. The warming effect is prominent at night, while the cooling effect dominates during the day. In both cases, the magnitude of the effect is dependent upon aerosol concentration. © 2017 Royal Meteorological Society"
"57200798349;57200790124;","Intercomparison between CMIP5 model and MODIS satellite-retrieved data of aerosol optical depth, cloud fraction, and cloud-aerosol interactions",2017,"10.1002/2017EA000288","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042452748&doi=10.1002%2f2017EA000288&partnerID=40&md5=7158558ba95096f1ea218875015d9613","Aerosols are a critical component of the Earth's atmosphere and can affect the climate of the Earth through their interactions with solar radiation and clouds. Cloud fraction (CF) and aerosol optical depth (AOD) at 550 nm from the Moderate Resolution Imaging Spectroradiometer (MODIS) are used with analogous cloud and aerosol properties from Historical Phase 5 of the Coupled Model Intercomparison Project (CMIP5) model runs that explicitly include anthropogenic aerosols and parameterized cloud-aerosol interactions. The models underestimate AOD by approximately 15% and underestimate CF by approximately 10% overall on a global scale. A regional analysis is then used to evaluate model performance in two regions with known biomass burning activity and absorbing aerosol (South America (SAM) and South Africa (SAF)). In SAM, the models overestimate AOD by 4.8% and underestimate CF by 14%. In SAF, the models underestimate AOD by 35% and overestimate CF by 13.4%. Average annual cycles show that the monthly timing of AOD peaks closely match satellite data in both SAM and SAF for all except the Community Atmosphere Model 5 and Geophysical Fluid Dynamics Laboratory (GFDL) models. Monthly timing of CF peaks closely match for all models (except GFDL) for SAM and SAF. Sorting monthly averaged 2° × 2.5° model or MODIS CF as a function of AOD does not result in the previously observed “boomerang”-shaped CF versus AOD relationship characteristic of regions with absorbing aerosols from biomass burning. Cloud-aerosol interactions, as observed using daily (or higher) temporal resolution data, are not reproducible at the spatial or temporal resolution provided by the CMIP5 models. ©2017. The Authors."
"55626987300;57194570535;8359721100;55207460700;8359720900;","Monitoring snow cover variability (2000–2014) in the Hengduan Mountains based on cloud-removed MODIS products with an adaptive spatio-temporal weighted method",2017,"10.1016/j.jhydrol.2017.05.049","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020914966&doi=10.1016%2fj.jhydrol.2017.05.049&partnerID=40&md5=895b84aa56cf85eebce682f3ed128b8f","Monitoring the variability of snow cover is necessary and meaningful because snow cover is closely connected with climate and ecological change. In this work, 500 m resolution MODIS daily snow cover products from 2000 to 2014 were adopted to analyze the status in Hengduan Mountains. In order to solve the spatial discontinuity caused by clouds in the products, we propose an adaptive spatio-temporal weighted method (ASTWM), which is based on the initial result of a Terra and Aqua combination. This novel method simultaneously considers the temporal and spatial correlations of the snow cover. The simulated experiments indicate that ASTWM removes clouds completely, with a robust overall accuracy (OA) of above 93% under different cloud fractions. The spatio-temporal variability of snow cover in the Hengduan Mountains was investigated with two indices: snow cover days (SCD) and snow fraction. The results reveal that the annual SCD gradually increases and the coefficient of variation (CV) decreases with elevation. The pixel-wise trends of SCD first rise and then drop in most areas. Moreover, intense intra-annual variability of the snow fraction occurs from October to March, during which time there is abundant snow cover. The inter-annual variability, which mainly occurs in high elevation areas, shows an increasing trend before 2004/2005 and a decreasing trend after 2004/2005. In addition, the snow fraction responds to the two climate factors of air temperature and precipitation. For the intra-annual variability, when the air temperature and precipitation decrease, the snow cover increases. Besides, precipitation plays a more important role in the inter-annual variability of snow cover than temperature. © 2017"
"12143017100;9249605700;56289106200;57194798077;16309604700;6603627233;36655323000;56483153400;","A multimodel intercomparison of an intense typhoon in future, warmer climates by Four 5-km-Mesh models",2017,"10.1175/JCLI-D-16-0715.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022326631&doi=10.1175%2fJCLI-D-16-0715.1&partnerID=40&md5=21d2fb9aad87b1751efab9e873bf4236","Intense tropical cyclones (TCs) sometimes cause huge disasters, so it is imperative to explore the impacts of climate change on such TCs. Therefore, the authors conducted numerical simulations of the most destructive historical TC in Japanese history, Typhoon Vera (1959), in the current climate and a global warming climate. The authors used four nonhydrostatic models with a horizontal resolution of 5 km: the cloud-resolving storm simulator, the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Mesoscale Model, the Japan Meteorological Agency (JMA) operational nonhydrostatic mesoscale model, and the Weather Research and Forecasting Model. Initial and boundary conditions for the control simulation were provided by the Japanese 55-year Reanalysis dataset. Changes between the periods of 1979-2003 and 2075-99 were estimated from climate runs of a 20-km-mesh atmospheric general circulation model, and these changes were added to the initial and boundary conditions of the control simulation to produce the future climate conditions. Although the representation of inner-core structures varies largely between the models, all models project an increase in the maximum intensity of future typhoons. It is found that structural changes only appeared around the storm center with sudden changes in precipitation and near-surface wind speeds as the radius of maximum wind speed (RMW) contracted. In the future climate, the water vapor mixing ratio in the lower troposphere increased by 3-4 g kg-1. The increased water vapor allowed the eyewall updrafts to form continuously inside the RMW and contributed to rapid condensation in the taller and more intense updrafts. © 2017 American Meteorological Society."
"7410069943;56532611600;8848948500;","Observational characteristics of cloud radiative effects over three arid regions in the Northern Hemisphere",2017,"10.1007/s13351-017-6166-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028332867&doi=10.1007%2fs13351-017-6166-7&partnerID=40&md5=3abfefa6bbb4d28a8cb58cc565f67eb3","Cloud–radiation processes play an important role in regional energy budgets and surface temperature changes over arid regions. Cloud radiative effects (CREs) are used to quantitatively measure the aforementioned climatic role. This study investigates the characteristics of CREs and their temporal variations over three arid regions in central Asia (CA), East Asia (EA), and North America (NA), based on recent satellite datasets. Our results show that the annual mean shortwave (SW) and net CREs (SWCRE and NCRE) over the three arid regions are weaker than those in the same latitudinal zone of the Northern Hemisphere. In most cold months (November–March), the longwave (LW) CRE is stronger than the SWCRE over the three arid regions, leading to a positive NCRE and radiative warming in the regional atmosphere–land surface system. The cold-season mean NCRE at the top of the atmosphere (TOA) averaged over EA is 4.1 W m–2, with a positive NCRE from November to March, and the intensity and duration of the positive NCRE is larger than that over CA and NA. The CREs over the arid regions of EA exhibit remarkable annual cycles due to the influence of the monsoon in the south. The TOA LWCRE over arid regions is closely related to the high-cloud fraction, and the SWCRE relates well to the total cloud fraction. In addition, the relationship between the SWCRE and the low-cloud fraction is good over NA because of the considerable occurrence of low cloud. Further results show that the interannual variation of TOA CREs is small over the arid regions of CA and EA, but their surface LWCREs show certain decreasing trends that correspond well to their decreasing total cloud fraction. It is suggested that combined studies of more observational cloud properties and meteorological elements are needed for indepth understanding of cloud–radiation processes over arid regions of the Northern Hemisphere. © 2017, The Chinese Meteorological Society and Springer-Verlag GmbH Germany."
"12142701800;56879003600;6506368946;9532846900;57194418044;7006553702;","Morpho-functional traits and plant response to drought conditions in seedlings of six native species of Ecuadorian Ecosystems",2017,"10.1016/j.flora.2017.05.012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020031294&doi=10.1016%2fj.flora.2017.05.012&partnerID=40&md5=6701bbe8a7844050a02a02aa1f4ac3c9","Tropical Andean ecosystems have been identified as very vulnerable to climate change. Changes in climatic conditions, especially drought as envisaged by climate change projections, could affect the establishment of new individuals that are responsible for ensuring the persistence of species and plant communities. The aim was to study the main morpho-functional traits related to water use and drought resistance of native plant species from Ecuadorian ecosystems during imposed drought periods. Seedlings of six native species representative of the Ecuadorian Andes were studied: lower montane evergreen forest (Alnus acuminata and Cedrela montana), montane cloud forest (Podocarpus sprucei and Aegiphila ferruginea) and montane dry shrubland (Schinus molle and Caesalpinia spinosa). Morphological characterisation, a root growth capacity test and stomatal conductance measurements during two controlled drought periods were used to investigate biomass allocation patterns, the root system morphology and gas exchange patterns of species, respectively. The main results indicated that species-specific differences in morpho-functional traits and allocation patterns determined responses to water availability and drought conditions. Low relative growth rate, leaf area ratio and specific leaf area, and high specific root length, were related to drought-resistant species as P. sprucei and C. spinosa. In contrast, a high or moderate relative growth rate, leaf area and root biomass, but low specific root length as in A. ferruginea, S. molle, C. montana, were related to lower resistance to drought conditions. Despite A. acuminata showed high specific root length, it was reported as a species sensitive to drought. Overall, patterns of stomatal conductance, linked to biomass allocation patterns and root system morphology, especially specific root length, seemed to be related to differences in vulnerability to drought in these species. Drought response was independent of species habitats. Unexpectedly, P. sprucei, belonging to montane cloud forest showed higher drought resistance than S. molle, belonging to montane dry shrubland. © 2017 Elsevier GmbH"
"56000854300;6602308024;57148220700;","Preliminary analysis of functional traits in cloud forest tree seedlings",2017,"10.1007/s00468-017-1543-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017144239&doi=10.1007%2fs00468-017-1543-5&partnerID=40&md5=af8fadff7cf289f6634c0ba2737fce57","Key message: Specific leaf area was the functional attribute of cloud forest tree seedlings that was most responsive to different light environments and was useful for distinguishing between two functional groups. Abstract: Cloud forests (CF) are highly diverse and severely threatened by deforestation, degradation, and climate change. Seedling transplantation of threatened and valuable tree species is a strategic technique that contributes to CF restoration; however, there is limited basic information regarding tree species functional traits and the microhabitat requirements for their reintroduction. Analysis of seedling functional traits could provide useful information to define functional groups and determine the potential of tree species to restore CF. We carried out a preliminary characterization of tree seedling functional traits in ten valuable CF species under a controlled environment. Six to nine months after germination, 50 seedlings per species were exposed to two light regimes (80 and 30% shade) and their growth, biomass allocation, and morphological responses were evaluated. After 9 months, most of the growth and biomass allocation parameters showed no significant differences between light regimes within species. However, specific leaf area (SLA) displayed significant differences between light regimes and also explained most of the variation among species. Based on a Principal Components Analysis, two main groups were identified: (1) Low SLA: Quercus germana, Quercussartorii, Sideroxylon contrerasii, Oreomunnea mexicana, and Ocotea disjuncta, and (2) high SLA: Ulmus mexicana, Liquidambar styraciflua, Meliosma alba, Magnolia dealbata, and Fraxinus uhdei. The suitability of functional groups and species in terms of the restoration of disturbed scenarios is discussed. © 2017, Springer-Verlag Berlin Heidelberg."
"9249239700;57203722524;56900293300;36150977900;57144839900;56130997600;6603126554;7202899330;55977336000;","Improved simulation of Antarctic sea ice due to the radiative effects of falling snow",2017,"10.1088/1748-9326/aa7a17","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029152126&doi=10.1088%2f1748-9326%2faa7a17&partnerID=40&md5=49b201039503753d182dc24426f68c78","Southern Ocean sea-ice cover exerts critical control on local albedo and Antarctic precipitation, but simulated Antarctic sea-ice concentration commonly disagrees with observations. Here we show that the radiative effects of precipitating ice (falling snow) contribute substantially to this discrepancy. Many models exclude these radiative effects, so they underestimate both shortwave albedo and downward longwave radiation. Using two simulations with the climate model CESM1, we show that including falling-snow radiative effects improves the simulations relative to cloud properties from CloudSat-CALIPSO, radiation from CERES-EBAF and sea-ice concentration from passive microwave sensors. From 50-70°S, the simulated sea-ice-area bias is reduced by 2.12 × 106 km2 (55%) in winter and by 1.17 × 106 km2 (39%) in summer, mainly because increased wintertime longwave heating restricts sea-ice growth and so reduces summer albedo. Improved Antarctic sea-ice simulations will increase confidence in projected Antarctic sea level contributions and changes in global warming driven by long-term changes in Southern Ocean feedbacks. © 2017 The Author(s). Published by IOP Publishing Ltd."
"56027675700;6505791231;","The effect of radiation parameterization schemes on surface temperature in regional climate simulations over the MENA-CORDEX domain",2017,"10.1002/joc.4959","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007072441&doi=10.1002%2fjoc.4959&partnerID=40&md5=77c0a4178f6ac717ed1c174c6a0efd64","We investigated the effect of radiation schemes on the performance of a climate version of the Weather, Research and Forecasting (CLWRF) model over a domain covering the Middle East and North Africa (MENA), so often called the Arab domain. The ability of the model to reproduce recent past climate conditions was tested with 30-year simulations that cover the 1981–2010 period. The model was driven by the ERA-Interim reanalyses at a horizontal resolution of 50 km. We explored the sensitivity of the model to the short- and long-wave (LW) radiation parameterizations by testing the RRTMG and CAM3 schemes in order to optimize the model performance as a contribution to the MENA-CORDEX initiative. The results have been compared with gridded surface observational data and satellite measurements for several variables, including mean, maximum and minimum 2-m air temperature, total cloud cover and surface short- and LW radiation fluxes. The model is found to capture reasonably well the inter-annual variability and the observed warming trends over the last three decades. Although we generally found that CAM3 driven simulations are relatively cooler than the RRTMG driven ones, each radiation scheme can give better results depending on the season, location and dominant land use type of each of the model's grid point. The largest discrepancies between these hindcast simulations are found over the desert part of the domain while they are found to closely agree over southern Europe. © 2016 Royal Meteorological Society"
"57193884115;6603109490;","Investigation of aerosol effects on the Arctic surface temperature during the diurnal cycle: part 2 – Separating aerosol effects",2017,"10.1002/joc.5075","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019165663&doi=10.1002%2fjoc.5075&partnerID=40&md5=df3ad83399ee83b8300707d89c545a64","Temperature changes in the Arctic due to anthropogenic climate change are larger in magnitude than those at lower latitudes, with sea ice extent and thickness diminishing since the dawn of the satellite era. Aerosols play a role in determining the changes to the Arctic surface temperature. While Part 1 of this two-part study investigated the changes in Arctic surface temperature due to the total aerosol effect, in Part 2, the total aerosol effect is separated into the changes caused by the aerosol direct effect, the aerosol semi-direct effect, and the aerosol indirect effects through the use of additional Weather Research and Forecasting Chemistry (WRF-Chem) runs. While Part 1 of the study showed that aerosols may have both a cooling and warming effect, largely depending upon the time of day and aerosol concentration, Part 2 of this study shows that the indirect effects are the dominant component of the total aerosol effect on the cooling and warming of the Arctic surface temperature throughout the diurnal cycle. It is also shown that the size distribution of aerosols is important, as smaller aerosols dominate the aerosol indirect effects. The aerosol direct effect contributes to cooling in the region, while the semi-direct effect is negligible. © 2017 Royal Meteorological Society"
"55268661300;55461837700;57196143493;","The influence of atmospheric cloud radiative effects on the large-scale stratospheric circulation",2017,"10.1175/JCLI-D-16-0643.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022334662&doi=10.1175%2fJCLI-D-16-0643.1&partnerID=40&md5=303841430869b0459903ba2d43bbe14e","Previous studies have explored the influence of atmospheric cloud radiative effects (ACRE) on the tropospheric circulation. Here the authors explore the influence of ACRE on the stratospheric circulation. The response of the stratospheric circulation to ACRE is assessed by comparing simulations run with and without ACRE. The stratospheric circulation response to ACRE is reproducible in a range of different GCMs and can be interpreted in the context of both a dynamically driven and a radiatively driven component. The dynamic component is linked to ACRE-induced changes in the vertical and meridional fluxes of wave activity. The ACRE-induced changes in the vertical flux of wave activity into the stratosphere are consistent with the ACRE-induced changes in tropospheric baroclinicity and thus the amplitude of midlatitude baroclinic eddies. They account for a strengthening of the Brewer-Dobson circulation, a cooling of the tropical lower stratosphere, a weakening and warming of the polar vortex, a reduction of static stability near the tropical tropopause transition layer, and a shortening of the time scale of extratropical stratospheric variability. The ACRE-induced changes in the equatorward flux of wave activity in the low-latitude stratosphere account for a strengthening of the zonal wind in the subtropical lower to midstratosphere. The radiative component is linked to ACRE-induced changes in the flux of longwave radiation into the lower stratosphere. The changes in radiative fluxes lead to a cooling of the extratropical lower stratosphere, changes in the static stability and cloud fraction near the extratropical tropopause, and a shortening of the time scales of extratropical stratospheric variability. The results highlight a previously overlooked pathway through which tropospheric climate influences the stratosphere. © 2017 American Meteorological Society."
"55614850300;34868072800;35339856200;24824869000;57190002566;57190007039;57190009555;57190007197;","Dynamical downscaling of regional climate over eastern China using RSM with multiple physics scheme ensembles",2017,"10.1007/s00704-016-1847-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976391708&doi=10.1007%2fs00704-016-1847-1&partnerID=40&md5=58e5ca799f969e2cdef1fc40a5db720e","The parameterization of physical processes is one of the critical elements to properly simulate the regional climate over eastern China. It is essential to conduct detailed analyses on the effect of physical parameterization schemes on regional climate simulation, to provide more reliable regional climate change information. In this paper, we evaluate the 25-year (1983–2007) summer monsoon climate characteristics of precipitation and surface air temperature by using the regional spectral model (RSM) with different physical schemes. The ensemble results using the reliability ensemble averaging (REA) method are also assessed. The result shows that the RSM model has the capacity to reproduce the spatial patterns, the variations, and the temporal tendency of surface air temperature and precipitation over eastern China. And it tends to predict better climatology characteristics over the Yangtze River basin and the South China. The impact of different physical schemes on RSM simulations is also investigated. Generally, the CLD3 cloud water prediction scheme tends to produce larger precipitation because of its overestimation of the low-level moisture. The systematic biases derived from the KF2 cumulus scheme are larger than those from the RAS scheme. The scale-selective bias correction (SSBC) method improves the simulation of the temporal and spatial characteristics of surface air temperature and precipitation and advances the circulation simulation capacity. The REA ensemble results show significant improvement in simulating temperature and precipitation distribution, which have much higher correlation coefficient and lower root mean square error. The REA result of selected experiments is better than that of nonselected experiments, indicating the necessity of choosing better ensemble samples for ensemble. © 2016, Springer-Verlag Wien."
"55482021100;6507576319;6701310647;6507283537;15055800700;23969559100;7202275216;6602518517;7003352529;","Regional sensitivities of seasonal snowpack to elevation, aspect, and vegetation cover in western North America",2017,"10.1002/2016WR019374","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029674620&doi=10.1002%2f2016WR019374&partnerID=40&md5=3dcd6cfb287911a8d92eca0996590913","In mountains with seasonal snow cover, the effects of climate change on snowpack will be constrained by landscape-vegetation interactions with the atmosphere. Airborne lidar surveys used to estimate snow depth, topography, and vegetation were coupled with reanalysis climate products to quantify these interactions and to highlight potential snowpack sensitivities to climate and vegetation change across the western U.S. at Rocky Mountain (RM), Northern Basin and Range (NBR), and Sierra Nevada (SNV) sites. In forest and shrub areas, elevation captured the greatest amount of variability in snow depth (16–79%) but aspect explained more variability (11–40%) in alpine areas. Aspect was most important at RM sites where incoming shortwave to incoming net radiation (SW:NetR↓) was highest (∼0.5), capturing 17–37% of snow depth variability in forests and 32–37% in shrub areas. Forest vegetation height exhibited negative relationships with snow depth and explained 3–6% of its variability at sites with greater longwave inputs (NBR and SNV). Variability in the importance of physiography suggests differential sensitivities of snowpack to climate and vegetation change. The high SW:NetR↓ and importance of aspect suggests RM sites may be more responsive to decreases in SW:NetR↓ driven by warming or increases in humidity or cloud cover. Reduced canopy-cover could increase snow depths at SNV sites, and NBR and SNV sites are currently more sensitive to shifts from snow to rain. The consistent importance of aspect and elevation indicates that changes in SW:NetR↓ and the elevation of the rain/snow transition zone could have widespread and varied effects on western U.S. snowpacks. © 2017. American Geophysical Union. All Rights Reserved."
"56135094100;7006367524;36665056700;25822837600;55555715100;","Sea and land surface temperatures, ocean heat content, Earth's energy imbalance and net radiative forcing over the recent years",2017,"10.1002/joc.4996","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011556695&doi=10.1002%2fjoc.4996&partnerID=40&md5=424e56c267dd5571194ec4c559745ed2","We investigate the global mean and regional change of sea surface and land surface temperature over 2003–2013, using a large number of different data sets, and compare with changes observed over the past few decades (starting in 1950). We find that over 2003–2013, both global land surface temperature and global sea surface temperature have increased at a rate significantly lower than over the previous decades. While confirming cooling of eastern tropical Pacific during the last decade as reported in several recent studies, our results show that the reduced rate of change of the 2003–2013 time span is a global phenomenon. GMST short-term trends since 1950 computed over successive 11-year windows with 1-year overlap show important decadal variability that highly correlates with 11-year trends of the Atlantic Multidecadal Oscillation index. The GMST 11-year trend distribution is well fitted by a Gaussian function, confirming an unforced origin related to internal climate variability. We evaluate the time derivative of full-depth ocean heat content to determine the planetary energy imbalance with different approaches: in situ measurements, ocean reanalysis and global sea level budget. For 2003–2013, it amounts to 0.5 +/− 0.1 W m−2, 0.68 +/− 0.1 W m−2 and 0.65 +/− 0.1 W m−2, respectively for the three approaches. Comparing with the Energy Balanced and Filled (EBAF) data of the Clouds and Earth's Radiant Energy Systems (CERES) project, we find significant agreement at interannual scales. Finally, using 15-year averages of GMST and total ocean heat content rate, we compute the net radiative forcing since 1970 (this start date being constrained by availability of ocean temperature data). Although the uncertainty is quite large because of considerable errors in the climate sensitivity parameter, we find no evidence of decrease in net radiative forcing in the recent years, but rather an increase compared to the previous decades. © 2017 Royal Meteorological Society"
"57193604462;56819057300;56040735400;7003807507;7103090287;8619523900;","The role of topography and the north Indian monsoon on mean monthly climate interpolation within the Himalayan Kingdom of Bhutan",2017,"10.1002/joc.5045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015235407&doi=10.1002%2fjoc.5045&partnerID=40&md5=3797f3a628f4129d5ec0ba5c3c6bef0e","Spatial climate datasets currently available for Bhutan are limited by weather station data availability, spatial resolution or interpolation methodology. This article presents new datasets for monthly maximum temperature, minimum temperature, precipitation and vapour pressure climate normals interpolated for the 1986–2015 reference period using trivariate smoothing splines. The inclusion of standardized day time Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) values as partial spline dependencies reduced cross validated root mean square error (RMSE) for maximum temperature by up to 16.0% and was most effective between March and September. Using both a topographic index of relative elevation and standardized night time MODIS LST values as partial spline dependencies reduced monthly mean minimum temperature RMSE by up to 23.4%. Neither variable was effective for minimum temperature interpolation between June and September. High humidity, extensive cloud cover and heavy precipitation occur during these months, which are likely to suppress the formation of temperature inversions that typically form under clear, calm conditions. These new temperature and precipitation surfaces show distinct differences from the WorldClim and CRU CL 2.0 datasets, which do not use weather stations within Bhutan for calibration. New precipitation surfaces better describe the heavy rainfall experienced in the southern foothills while retaining the effect of orography throughout the central valleys and ranges. The development of vapour pressure surfaces also allow for the calculation of ecologically important variables such as vapour pressure deficit, and may also be useful for solar radiation modelling in the region. The different datasets presented in this article will facilitate ecological and agricultural research in Bhutan and provide high quality surfaces needed for future climate change scenarios. © 2017 Royal Meteorological Society"
"57193891513;7006235116;","Variability in the Botswana High and its relationships with rainfall and temperature characteristics over southern Africa",2017,"10.1002/joc.5022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017403984&doi=10.1002%2fjoc.5022&partnerID=40&md5=64c14cdc75c5302e2b13c4b47928a063","The seasonal and interannual variability of the mid-tropospheric Botswana High and its relationships with various characteristics of rainfall and temperature over southern Africa are examined. This High typically forms in August and then strengthens and moves southward over southern Africa during the spring and summer. It also expands in zonal extent so that by March it is part of an anticyclonic ridge extending from the South Atlantic Convergence Zone eastwards over this ocean, across southern Africa and to the western Indian Ocean, with its greatest intensity in February. Its position is always to the south and southeast of the region of heavy precipitation across tropical southern Africa associated with the Inter Tropical Convergence Zone (ITCZ) and its meridional arm that passes through the eastern Congo Basin. Substantial interannual variability exists in the strength of the Botswana High. While the High is typically stronger (weaker) during El Niño (La Niña) events, there are also a number of neutral El Niño Southern Oscillation (ENSO) summers with large anomalies in the Botswana High. Neutral summers with an anomalously weak Botswana High are also characterized by a cyclonic anomaly extending from Angola south to the Antarctic and an anticyclonic anomaly over the South West Indian Ocean. These circulation patterns favour the development of tropical extratropical cloud bands, the main synoptic summer rainfall producing system, and the inflow of more moisture from the Indian Ocean towards the source of the cloud bands and hence increased rainfall. Roughly, the reverse circulation anomalies occur during neutral summers with anomalously large values of the Botswana High. Relationships are also found between the Botswana High and dry spell frequency, maximum temperature, diurnal temperature range and the number of days with extreme temperatures during the summer. © 2017 Royal Meteorological Society"
"56190076100;7501627905;","A revival of Indian summer monsoon rainfall since 2002",2017,"10.1038/NCLIMATE3348","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026633664&doi=10.1038%2fNCLIMATE3348&partnerID=40&md5=802a919aca5217f97c72972f57dbdc0f","A significant reduction in summer monsoon rainfall has been observed in northern central India during the second half of the twentieth century, threatening water security and causing widespread socio-economic impacts. Here, using various observational data sets, we show that monsoon rainfall has increased in India at 1.34 mm d(-1) decade(-1) since 2002. This apparent revival of summer monsoon precipitation is closely associated with a favourable land-ocean temperature gradient, driven by a strong warming signature over the Indian subcontinent and slower rates of warming over the Indian Ocean. The continental Indian warming is attributed to a reduction of low cloud due to decreased ocean evaporation in the Arabian Sea, and thus decreased moisture transport to India. Global climate models fail to capture the observed rainfall revival and corresponding trends of the land-ocean temperature gradient, with implications for future projections of the Indian monsoon. © 2017 Macmillan Publishers Limited, part of Springer Nature."
"49662076300;","Development of a global aerosol model using a two-dimensional sectional method: 1. Model design",2017,"10.1002/2017MS000936","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029360690&doi=10.1002%2f2017MS000936&partnerID=40&md5=71f515002044b558d8717a32964044b0","This study develops an aerosol module, the Aerosol Two-dimensional bin module for foRmation and Aging Simulation version 2 (ATRAS2), and implements the module into a global climate model, Community Atmosphere Model. The ATRAS2 module uses a two-dimensional (2-D) sectional representation with 12 size bins for particles from 1 nm to 10 μm in dry diameter and 8 black carbon (BC) mixing state bins. The module can explicitly calculate the enhancement of absorption and cloud condensation nuclei activity of BC-containing particles by aging processes. The ATRAS2 module is an extension of a 2-D sectional aerosol module ATRAS used in our previous studies within a framework of a regional three-dimensional model. Compared with ATRAS, the computational cost of the aerosol module is reduced by more than a factor of 10 by simplifying the treatment of aerosol processes and 2-D sectional representation, while maintaining good accuracy of aerosol parameters in the simulations. Aerosol processes are simplified for condensation of sulfate, ammonium, and nitrate, organic aerosol formation, coagulation, and new particle formation processes, and box model simulations show that these simplifications do not substantially change the predicted aerosol number and mass concentrations and their mixing states. The 2-D sectional representation is simplified (the number of advected species is reduced) primarily by the treatment of chemical compositions using two interactive bin representations. The simplifications do not change the accuracy of global aerosol simulations. In part 2, comparisons with measurements and the results focused on aerosol processes such as BC aging processes are shown. © 2017. The Authors."
"6701314322;","Transit detection of a 'starshade' at the inner lagrange point of an exoplanet",2017,"10.1093/mnras/stx1078","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048595453&doi=10.1093%2fmnras%2fstx1078&partnerID=40&md5=da10ec13286646e5f5138b654ca85196","All water-covered rocky planets in the inner habitable zones of solar-type stars will inevitably experience a catastrophic runaway climate due to increasing stellar luminosity and limits to outgoing infrared radiation from wet greenhouse atmospheres. Reflectors or scatterers placed near Earth's inner Lagrange point (L1) have been proposed as a ""geoengineering' solution to anthropogenic climate change and an advanced version of this could modulate incident irradiation over many Gyr or 'rescue' a planet from the interior of the habitable zone. The distance of the starshade from the planet that minimizes its mass is 1.6 times the Earth-L1 distance. Such a starshade would have to be similar in size to the planet and the mutual occultations during planetary transits could produce a characteristic maximum at mid-transit in the light curve. Because of a fortuitous ratio of densities, Earth-size planets around G dwarf stars present the best opportunity to detect such an artefact. The signal would be persistent and is potentially detectable by a future space photometry mission to characterize transiting planets. The signal could be distinguished from natural phenomenon, i.e. starspots or cometary dust clouds, by its shape, persistence and transmission spectrum. © 2017 The Authors."
"56197377000;57054231600;11840367400;","Detection of asian dust storm using MODIS measurements",2017,"10.3390/rs9080869","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028305968&doi=10.3390%2frs9080869&partnerID=40&md5=420f2ec83bb24c403712b3f737bd0169","Every year, a large number of aerosols are released from dust storms into the atmosphere, which may have potential impacts on the climate, environment, and air quality. Detecting dust aerosols and monitoring their movements and evolutions in a timely manner is a very significant task. Satellite remote sensing has been demonstrated as an effective means for observing dust aerosols. In this paper, an algorithm based on the multi-spectral technique for detecting dust aerosols was developed by combining measurements of moderate resolution imaging spectroradiometer (MODIS) reflective solar bands and thermal emissive bands. Data from dust events that occurred during the past several years were collected as training data for spectral and statistical analyses. According to the spectral curves of various scene types, a series of spectral bands was selected individually or jointly, and corresponding thresholds were defined for step-by-step scene classification. The multi-spectral algorithm was applied mainly to detect dust storms in Asia. The detection results were validated not only visually with MODIS true color images, but also quantitatively with products of Ozone Monitoring Instrument (OMI) and Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP). The validations showed that this multi-spectral detection algorithm was suitable to monitor dust aerosols in the selected study areas. © 2017 by the authors."
"56055143800;35744799500;57207492767;56358203500;7403394522;16300900500;","Climatology and trends of air and soil surface temperatures in the temperate steppe region of North China",2017,"10.1002/joc.5076","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017415598&doi=10.1002%2fjoc.5076&partnerID=40&md5=5ebe62a3d2da1db55d6565b28324438f","We analysed observations of daily maximum and minimum air and soil surface temperatures collected between 1965 and 2007 in the temperate steppe region of North China to understand the climatology and trends of the diurnal temperature range. Sunshine duration and precipitation records were also analysed for their relationships with the changes in temperatures. In general, the daily maximum soil surface temperatures (SSTmax) are generally much higher than the daily maximum air temperature (Tmax), and the daily minimum soil surface temperature (SSTmin) are slightly lower than the daily minimum air temperature (Tmin) throughout the year. Consequently, the soil surface diurnal temperature range (SSDTR) is much higher than diurnal temperature range of air temperatures (DTR). As with air temperatures, soil surface temperatures have warmed significantly over the study period at most stations, increasing by 0.62 °C per decade for SSTmax and 0.64 °C per decade for SSTmin for the region overall. Annual and seasonal SSTmax and SSTmin have increased faster than Tmax and Tmin, except for SSTmax in winter. Declines in air DTR have been commonly observed, but in our study SSDTR decreases only in winter, driven by a steep decline after 2000, mostly resulting from strong increases in SSTmin and slight decreases in SSTmax. Both annual and seasonal calculations indicate that the decline in air DTR mainly coincided with a period of rapid decrease in sunshine duration before 1990. Total cloud amount decreased during this period, so the changes in total cloud amount could not be the cause for decrease in sunshine duration and DTR before 1990. SSDTR shows a different pattern: the rapid decrease of SSDTR in winter season since the end of 1990 coincides with a decrease in sunshine duration and an increase in total cloud amount, which may have contributed to the decrease in winter SSDTR in the new millennium. © 2017 Royal Meteorological Society"
"57195946585;56067767500;","Downscaling of MODIS land surface temperature to LANDSAT scale using multi-layer perceptron",2017,"10.7848/ksgpc.2017.35.4.313","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030320620&doi=10.7848%2fksgpc.2017.35.4.313&partnerID=40&md5=d1cc028ae043ad0b64f405f0d964abc0","Land surface temperature is essential for monitoring abnormal climate phenomena such as UHI (Urban Heat Islands), and for modeling weather patterns. However, the quality of surface temperature obtained from the optical space imagery is affected by many factors such as, revisit period of the satellite, instance of capture, spatial resolution, and cloud coverage. Landsat 8 imagery, often used to obtain surface temperatures, has a high resolution of 30 meters (100 meters rearranged to 30 meters) and a revisit frequency of 16 days. On the contrary, MODIS imagery can be acquired daily with a spatial resolution of about 1 kilometer. Many past attempts have been made using both Landsat and MODIS imagery to complement each other to produce an imagery of improved temporal and spatial resolution. This paper applied machine learning methods and performed downscaling which can obtain daily based land surface temperature imagery of 30 meters."
"57195286272;55713076400;7201654851;","Effects of artificial local compensation of convective mass flux in the cumulus parameterization",2017,"10.1002/2017MS000926","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026733167&doi=10.1002%2f2017MS000926&partnerID=40&md5=19a90fe9b0de400296e8ea14da23ed96","In this study, a hybrid mass flux cumulus scheme (HYMACS) is developed for the Weather Research and Forecasting Model (WRF). Idealized experiments are performed to evaluate its effects on tropical cyclone simulations. Classical cumulus schemes assume artificial local compensation of convective mass flux. In contrast, HYMACS treats subgrid-scale mass flux convergence or divergence as parameterized mass sources or sinks. When the mass sources or sinks are introduced to the mass continuity equation in a nonhydrostatic fully compressible model, the model dynamics would resolve the mass-compensating motion, i.e., dynamic compensation of convective mass flux. A hierarchy of experiments is conducted to demonstrate the effects of the artificial local compensation. The results of the mass compensation experiment show that the amplitude of the column mass change with the artificial local compensation is more sensitive to the change of the horizontal resolution between 3 and 27 km than the dynamic compensation. The results of the piggybacking tropical cyclone simulations at 9 km resolution suggest that the artificial local compensation in the Kain-Fritsch scheme (KF) concentrates vertical exchange of dry static energy and moisture and induces secondary circulation, which could lead to sea level pressure decrease and enhanced precipitation. These results indicate that the artificial local compensation at the gray-zone resolution could cause significant effects on tropical cyclone dynamics, so it is important to avoid the artificial local compensation for cumulus parameterization at such resolution. © 2017. The Authors."
"55877698400;55796506900;56276311500;7410070663;","Simulated effects of internal mixing of anthropogenic aerosols on the aerosol–radiation interaction and global temperature",2017,"10.1002/joc.5050","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019075993&doi=10.1002%2fjoc.5050&partnerID=40&md5=b982c215458f79df5041d392cd6b2236","A partial internal mixing (PIM) treatment of black carbon (BC), organic carbon (OC), and sulphate was examined, and the core-shell model was used to represent the internally mixed aerosols with BC as the core and sulphate or OC as the shell. The influences of PIM treatment on the effective radiative forcing due to aerosol–radiative interaction (ERFari) and global temperature were examined and compared to those of external mixing (EM) treatment using an aerosol-climate online coupled model of BCC_AGCM2.0_CUACE/Aero. Radiative forcing due to aerosol–radiation interaction (RFari) of the anthropogenic aerosols since the preindustrial era was −0.34 W m−2 for EM and −0.23 W m−2 for PIM, respectively. The global annual mean ERFari of anthropogenic aerosols since the preindustrial era was −0.42 W m−2 for EM and −0.34 W m−2 for PIM, respectively. The change in global annual mean surface temperature increased accordingly from −0.18 K in the EM case to −0.125 K in the PIM case. Well geographic consistence between the change in low-level cloud amount and the change in temperature can be found. The atmospheric temperature in the troposphere was markedly less reduced in the PIM case than in the EM case. The RFari/ERFari for 50% and 100% were −0.11/–0.07 and 0.13/0.14 W m−2, respectively. RFari, ERFari, and surface temperature changed approximately linearly with the internal mixing proportion. © 2017 Royal Meteorological Society"
"6701519241;54392542400;55934587900;35615593500;","Super-Clausius-Clapeyron scaling of extreme hourly convective precipitation and its relation to large-scale atmospheric conditions",2017,"10.1175/JCLI-D-16-0808.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022331052&doi=10.1175%2fJCLI-D-16-0808.1&partnerID=40&md5=1fae02bf910749aca6aa95450bcea57d","Present-day precipitation-temperature scaling relations indicate that hourly precipitation extremes may have a response to warming exceeding the Clausius-Clapeyron (CC) relation; for the Netherlands the dependency on surface dewpoint temperature follows 2 times the CC relation (2CC). The authors' hypothesis- as supported by a simple physical argument presented here-is that this 2CC behavior arises from the physics of convective clouds. To further investigate this, the large-scale atmospheric conditions accompanying summertime afternoon precipitation events are analyzed using surface observations combined with a regional reanalysis. Events are precipitation measurements clustered in time and space. The hourly peak intensities of these events again reveal a 2CC scaling with the surface dewpoint temperature. The temperature excess of moist updrafts initialized at the surface and the maximumcloud depth are clear functions of surface dewpoint, confirming the key role of surface humidity on convective activity. Almost no differences in relative humidity and the dry temperature lapse rate were found across the dewpoint temperature range, supporting the theory that 2CC scaling is mainly due to the response of convection to increases in near-surface humidity, while other atmospheric conditions remain similar. Additionally, hourly precipitation extremes are on average accompanied by substantial large-scale upward motions and therefore large-scale moisture convergence, which appears to accelerate with surface dewpoint. Consequently, most hourly extremes occur in precipitation events with considerable spatial extent. Importantly, this event size appears to increase rapidly at the highest dewpoint temperature range, suggesting potentially strong impacts of climatic warming. © 2017 American Meteorological Society."
"7402085600;57193748450;57191968577;57205772406;24801829100;7401895830;","Contributions of Asian pollution and SST forcings on precipitation change in the North Pacific",2017,"10.1016/j.atmosres.2017.03.014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016245894&doi=10.1016%2fj.atmosres.2017.03.014&partnerID=40&md5=3dd9b8614898aace99a501f75a2eefe4","East Asia has a significant concentration of pollutant aerosols, mostly due to rapid industrialization. Previous research indicates that the aerosol effect from Asian pollution outflow could account for the trend of increasing deep convective clouds, as well as an intensification of the storm track, over the North Pacific Ocean in winter since the mid-1990s. However, it is not clear whether such change is solely due to Asian pollutant forcings or not. To understand the relative roles of Asian pollutant aerosols and sea surface temperature (SST) forcings on the precipitation change in the North Pacific, we examine the interannual variation of particulate matter 2.5 (PM2.5) simulated in the global chemical transport model (GEOS-Chem) and the idealized experiments using the Community Atmosphere Model version 5 (CAM5) for 1986–2010. The composite analysis indicates that the changes in precipitation amount and storm track intensity in the southwestern North Pacific might be associated with the increase in PM2.5 concentration in East China. However, El Niño-like warming during the years of high PM2.5 concentration may also influence the precipitation amount, as well as the storm track intensity in the central and eastern North Pacific. Model experiments also indicate that the El Niño-like warming and the Asian pollutant aerosols have different effects on precipitation amounts in the North Pacific. Therefore, the precipitation changes, as well as the intensification of the storm track, in the North Pacific might be attributed to both Asian pollutant aerosols and SST forcing in the tropics. © 2017 Elsevier B.V."
"57213967598;36606783400;24329947300;7004351010;8548304600;8836278700;","Satellite-retrieved direct radiative forcing of aerosols over North-East India and adjoining areas: climatology and impact assessment",2017,"10.1002/joc.5004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013249507&doi=10.1002%2fjoc.5004&partnerID=40&md5=22cdb3a939c330ec4d505bca3483662a","In order to understand the climatic implications of atmospheric aerosols, top of atmosphere (TOA) shortwave (SW, 0.3–5 µm) fluxes and aerosol optical depth (AOD) at 550 nm retrieved simultaneously by clouds and the earth's radiant energy system (CERES) and moderate resolution imaging spectroradiometer (MODIS) instruments, respectively, are analysed over North-East India and its adjoining areas for the period July 2002–December 2013. The aerosol-free TOA flux obtained by establishing the linear regression between CERES SW TOA fluxes and MODIS AODs exhibits strong seasonality with peak values in monsoon and minimum in winter. Same seasonality is captured by the Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model, but with difference in absolute values. SBDART code is used to extend instantaneous radiative forcing estimates into 24-h averages. AOD over the North East India region with complex terrain shows altitudinal variation with maximum value at the lowest elevation site Dhaka and minimum value at the high-altitude locations Shillong and Aizwal. In general, strong seasonality in AOD is observed with a peak in pre-monsoon (March–May) and dip in post-monsoon (October–November) at all the locations. The direct instantaneous TOA shortwave aerosol radiative forcing (SWARF) shows maximum values in pre-monsoon over all the locations except at Guwahati, Banmauk, Aizawl, and Shillong. The lowest value of instantaneous SWARF is observed in post-monsoon except at Banmauk and Shillong. Climatologically TOA diurnally averaged SWARF varies between −6.95 W m−2 in Aizawl to −20.39 W m−2 in Shillong. In general, the TOA SW forcing efficiency is highest in monsoon at all the locations. The radiative forcing efficiency is found to be less negative when surface reflectance increases. © 2017 Royal Meteorological Society"
"56382798500;35105101800;7102913661;","Sensitivity of simulated convection-driven stratosphere-troposphere exchange in WRF-Chem to the choice of physical and chemical parameterization",2017,"10.1002/2017EA000287","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042454970&doi=10.1002%2f2017EA000287&partnerID=40&md5=815c18346263c0b6eaec8cee03ead88f","Tropopause-penetrating convection is capable of rapidly transporting air from the lower troposphere to the upper troposphere and lower stratosphere (UTLS), where it can have important impacts on chemistry, the radiative budget, and climate. However, obtaining in situ measurements of convection and convective transport is difficult and such observations are historically rare. Modeling studies, on the other hand, offer the advantage of providing output related to the physical, dynamical, and chemical characteristics of storms and their environments at fine spatial and temporal scales. Since these characteristics of simulated convection depend on the chosen model design, we examine the sensitivity of simulated convective transport to the choice of physical (bulk microphysics or BMP and planetary boundary layer or PBL) and chemical parameterizations in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). In particular, we simulate multiple cases where in situ observations are available from the recent (2012) Deep Convective Clouds and Chemistry (DC3) experiment. Model output is evaluated using ground-based radar observations of each storm and in situ trace gas observations from two aircraft operated during the DC3 experiment. Model results show measurable sensitivity of the physical characteristics of a storm and the transport of water vapor and additional trace gases into the UTLS to the choice of BMP. The physical characteristics of the storm and transport of insoluble trace gases are largely insensitive to the choice of PBL scheme and chemical mechanism, though several soluble trace gases (e.g., SO2, CH2O, and HNO3) exhibit some measurable sensitivity. ©2017. The Authors."
"57191967300;7003415001;7004902765;","Revisiting Ocean Color algorithms for chlorophyll a and particulate organic carbon in the Southern Ocean using biogeochemical floats",2017,"10.1002/2017JC012844","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029431299&doi=10.1002%2f2017JC012844&partnerID=40&md5=32c8c85a77cdc1881d4e12c506c355dd","The Southern Ocean (SO) ecosystem plays a key role in the carbon cycle by sinking a major part (43%) of the ocean uptake of anthropogenic CO2, and being an important source of nutrients for primary producers. However, undersampling of SO biogeochemical properties limits our understanding of the mechanisms taking place in this remote area. The Southern Ocean Carbon and Climate Observations and Modeling (SOCCOM) project has been deploying a large number of autonomous biogeochemical floats to study the SO (as of December 2016, 74 floats out of 200 have been deployed). SOCCOM floats measurements can be used to extend remote sensing chlorophyll a (chl a) and particulate organic carbon (POC) products under clouds or during the polar night as well as adding the depth dimension to the satellite-based view of the SO. Chlorophyll a concentrations measured by a sensor embedded on the floats and POC concentrations derived from backscattering coefficients were calibrated with samples collected during the floats' deployment cruise. Float chl a and POC were compared with products derived from observations of MODIS and VIIRS sensors. We find the Ocean Color Index (OCI) global algorithm to agree well with the matchups (within 9%, on average, for the Visible Infrared Imaging Radiometer Suite (VIIRS) and 12%, on average, for the Moderate Resolution Imaging Spectroradiometer Aqua (MODIS)). SO-specific algorithms estimating chl a are offset by ∼45% south of the Sea Ice Extent Front (∼60°S). In addition, POC estimates based on floats agree well with NASA's POC algorithm. © 2017. The Authors."
"7201897043;57104288000;57189644727;","High-resolution regional-coupled ocean–atmosphere simulation of the Indian Summer Monsoon",2017,"10.1002/joc.5034","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015328784&doi=10.1002%2fjoc.5034&partnerID=40&md5=05bd63aacd4443b4b1a3387e93e53806","A 23-year integration of a Regional-Coupled Ocean–Atmosphere Model (RCOAM) centred over the Indian monsoon region is validated with observations and analysis for its seasonal climatology, evolution, and variability at intraseasonal and interannual scales. The RCOAM has the Regional Spectral Model (RSM) as its atmospheric component and Regional Ocean Model System (ROMS) as its oceanic component. They are both coupled at 15 km grid spacing with identical grids, without applying any form of flux correction and are forced with global fields of atmospheric and oceanic reanalysis. The verification indicates that the RCOAM simulation simulates the mean Indian Summer Monsoon (ISM) rainfall climatology and SST in the neighbouring oceans reasonably well with finer details apparent along the orography (e.g. Western Ghats, Himalaya) and along the upwelling regions of the coastal oceans. In addition the evolution of the ISM at its onset and its devolution around the time of demise in the RCOAM simulation both in the atmosphere and the ocean conform to its well known features and reinforce the coupled ocean–atmosphere phenomenon of the ISM. The intraseasonal variations in the RCOAM simulation also adhere to the observed composite of dry and wet spells of the ISM, with the low-level flow in the latter (former) counteracting (enhancing) the low-level atmospheric ISM climatological flow. The interannual variations in relation to the remote ENSO variations are also validated with respect to the observations. It is also shown that the variations of the length of the ISM to the seasonal anomalies of the ISM both in the RCOAM simulation and observations is largely a result of the ENSO teleconnection. However, significant systematic bias in surface fluxes, cloud fraction, SST, and precipitation of the RCOAM simulation of the ISM is also noted. © 2017 Royal Meteorological Society"
"57183432400;7404210446;14058925000;55977333800;57183438500;57183244900;57061376800;","An analysis on the influence of spatial scales on sensible heat fluxes in the north Tibetan Plateau based on Eddy covariance and large aperture scintillometer data",2017,"10.1007/s00704-016-1809-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84968619408&doi=10.1007%2fs00704-016-1809-7&partnerID=40&md5=acb0395860a9934c9e08a89acc52b008","The influence of spatial scales on surface fluxes is an interesting but not fully investigated question. This paper presents an analysis on the influence of spatial scales on surface fluxes in the north Tibetan Plateau based on eddy covariance (EC) and large aperture scintillometer (LAS) data at site Nagqu/BJ, combined with the land surface temperature (LST) and normalized difference vegetation index (NDVI) of moderate-resolution imaging spectroradiometer (MODIS). The analysis shows that sensible heat fluxes calculated with LAS data (H_LAS) agree reasonably well with sensible heat fluxes calculated with EC data (H_EC) in the rain and dry seasons. The difference in their footprints due to the wind direction is an important reason for the differences in H_EC and H_LAS. The H_LAS are statistically more consistent with H_EC when their footprints overlap than when their footprints do not. A detailed analysis on H_EC and H_LAS changes with net radiation and wind direction in rain and dry season indicates that the spatial heterogeneity in net radiation created by clouds contributes greatly to the differences in H_EC and H_LAS in short-term variations. A significant relationship between the difference in footprint-weighted averages of LST and difference in H_EC and H_LAS suggests that the spatial heterogeneity in LST at two spatial scales is a reason for the differences in H_EC and H_LAS and that LST has a positive correlation with the differences in H_EC and H_LAS. A significant relationship between the footprint-weighted averages of NDVI and the ratio of sensible heat fluxes at two spatial scales to net radiation (H/Rn) in the rain season supports the analysis that the spatial heterogeneity in canopy at two spatial scales is another reason for differences in H_EC and H_LAS and that canopy has a negative correlation with (H/Rn). An analysis on the influence of the difference in aerodynamic roughness lengths at two spatial scales on sensible heat fluxes shows that the influence is greater in the dry season and smaller in the rain season because the ratio of z0m_LAS to z0m_EC is big in the dry season and is close to 1.0 in the rain season. This study on spatial scales on surface fluxes in the Tibetan Plateau will be helpful in analyzing and understanding its influence on climate. © 2016, Springer-Verlag Wien."
"57195245415;12801992200;7102495313;","Cloud albedo changes in response to anthropogenic sulfate and non-sulfate aerosol forcings in CMIP5 models",2017,"10.5194/acp-17-9145-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026549487&doi=10.5194%2facp-17-9145-2017&partnerID=40&md5=c1562b1ab93c73c027b3a1ff15f99ba1","The effects of different aerosol types on cloud albedo are analysed using the linear relation between total albedo and cloud fraction found on a monthly mean scale in regions of subtropical marine stratocumulus clouds and the influence of simulated aerosol variations on this relation. Model experiments from the Coupled Model Intercomparison Project phase 5 (CMIP5) are used to separately study the responses to increases in sulfate, non-sulfate and all anthropogenic aerosols. A cloud brightening on the month-to-month scale due to variability in the background aerosol is found to dominate even in the cases where anthropogenic aerosols are added. The aerosol composition is of importance for this cloud brightening, that is thereby region dependent. There is indication that absorbing aerosols to some extent counteract the cloud brightening but scene darkening with increasing aerosol burden is generally not supported, even in regions where absorbing aerosols dominate. Month-to-month cloud albedo variability also confirms the importance of liquid water content for cloud albedo. Regional, monthly mean cloud albedo is found to increase with the addition of anthropogenic aerosols and more so with sulfate than non-sulfate. Changes in cloud albedo between experiments are related to changes in cloud water content as well as droplet size distribution changes, so that models with large increases in liquid water path and/or cloud droplet number show large cloud albedo increases with increasing aerosol. However, no clear relation between model sensitivities to aerosol variations on the month-to-month scale and changes in cloud albedo due to changed aerosol burden is found. © 2017 Author(s)."
"6506512863;40461229800;35553423100;8550791300;57203104770;37361047600;56518267700;7003771728;56605058800;24068728200;7402177459;23100367400;15923105200;55308171300;7004683326;56673781300;50162008400;55942083800;56483253400;57190177542;56012359800;7006415284;7004364676;10540059100;","Perspectives on the future of ice nucleation research: Research needs and Unanswered questions identified from two international workshops",2017,"10.3390/atmos8080138","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027460190&doi=10.3390%2fatmos8080138&partnerID=40&md5=e51accdda8ed366b6f52c0fe71721787","There has been increasing interest in ice nucleation research in the last decade. To identify important gaps in our knowledge of ice nucleation processes and their impacts, two international workshops on ice nucleation were held in Vienna, Austria in 2015 and 2016. Experts from these workshops identified the following research needs: (1) uncovering the molecular identity of active sites for ice nucleation; (2) the importance of modeling for the understanding of heterogeneous ice nucleation; (3) identifying and quantifying contributions of biological ice nuclei from natural and managed environments; (4) examining the role of aging in ice nuclei; (5) conducting targeted sampling campaigns in clouds; and (6) designing lab and field experiments to increase our understanding of the role of ice-nucleating particles in the atmosphere. Interdisciplinary teams of scientists should work together to establish and maintain a common, unified language for ice nucleation research. A number of commercial applications benefit from ice nucleation research, including the production of artificial snow, the freezing and preservation of water-containing food products, and the potential modulation of weather. Additional work is needed to increase our understanding of ice nucleation processes and potential impacts on precipitation, water availability, climate change, crop health, and feedback cycles. 2017 by the authors. Licensee MDPI, Basel, Switzerland."
"35301550500;57188628141;10042470700;7004807312;","Simultaneous stabilization of global temperature and precipitation through cocktail geoengineering",2017,"10.1002/2017GL074281","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028518680&doi=10.1002%2f2017GL074281&partnerID=40&md5=92a3e83a489e894c6406ca5f6141a120","Solar geoengineering has been proposed as a backup plan to offset some aspects of anthropogenic climate change if timely CO2 emission reductions fail to materialize. Modeling studies have shown that there are trade-offs between changes in temperature and hydrological cycle in response to solar geoengineering. Here we investigate the possibility of stabilizing both global mean temperature and precipitation simultaneously by combining two geoengineering approaches: stratospheric sulfate aerosol increase (SAI) that deflects sunlight to space and cirrus cloud thinning (CCT) that enables more longwave radiation to escape to space. Using the slab ocean configuration of National Center for Atmospheric Research Community Earth System Model, we simulate SAI by uniformly adding sulfate aerosol in the upper stratosphere and CCT by uniformly increasing cirrus cloud ice particle falling speed. Under an idealized warming scenario of abrupt quadrupling of atmospheric CO2, we show that by combining appropriate amounts of SAI and CCT geoengineering, global mean (or land mean) temperature and precipitation can be restored simultaneously to preindustrial levels. However, compared to SAI, cocktail geoengineering by mixing SAI and CCT does not markedly improve the overall similarity between geoengineered climate and preindustrial climate on regional scales. Some optimal spatially nonuniform mixture of SAI with CCT might have the potential to better mitigate climate change at both the global and regional scales. ©2017. American Geophysical Union. All Rights Reserved."
"35095482200;7403282069;6506234624;7006783796;","Entrainment rate diurnal cycle in marine stratiform clouds estimated from geostationary satellite retrievals and a meteorological forecast model",2017,"10.1002/2017GL074481","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85024396430&doi=10.1002%2f2017GL074481&partnerID=40&md5=fc235cc87f28ff42c9dab82fe7b576f0","The mean diurnal cycle of cloud entrainment rate (we) over the northeast Pacific region is for the first time computed by combining, in a mixed-layer model framework, the hourly composited GOES-15 satellite-based cloud top height (HT) tendency, advection, and large-scale vertical velocity (w) during May to September 2013, with horizontal winds and w taken from the European Centre for Medium-Range Weather Forecasts (ECMWF) model. The tendency term dominates the magnitude and phase of the we diurnal cycle, with a secondary role of w, and a modest advective contribution. The peak and minimum in we occur between 20:00–22:00 LT and 9:00–11:00 LT, respectively, in close agreement with the diurnal cycle of turbulence driven by cloud top longwave cooling. Uncertainties in HT and ECMWF fields are assessed with in situ observations and three meteorological reanalysis data sets. This study provides the basis for constructing nearly global climatologies of we by combining a suite of well-calibrated geostationary satellites. ©2017. American Geophysical Union. All Rights Reserved."
"55706282100;57192695511;57191341169;55638979500;57203174863;12645612500;57206332144;7404548584;55476786400;","Passive remote sensing of altitude and optical depth of dust plumes using the oxygen A and B bands: First results from EPIC/DSCOVR at Lagrange-1 point",2017,"10.1002/2017GL073939","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026457694&doi=10.1002%2f2017GL073939&partnerID=40&md5=d0ee36ce768b6b3be89a28dffe660c2c","We presented an algorithm for inferring aerosol layer height (ALH) and optical depth (AOD) over ocean surface from radiances in oxygen A and B bands measured by the Earth Polychromatic Imaging Camera (EPIC) on the Deep Space Climate Observatory (DSCOVR) orbiting at Lagrangian-1 point. The algorithm was applied to EPIC imagery of a 2 day dust outbreak over the North Atlantic Ocean. Retrieved ALHs and AODs were evaluated against counterparts observed by Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), Moderate Resolution Imaging Spectroradiometer, and Aerosol Robotic Network. The comparisons showed 71.5% of EPIC-retrieved ALHs were within ±0.5 km of those determined from CALIOP and 74.4% of EPIC AOD retrievals fell within a ± (0.1 + 10%) envelope of MODIS retrievals. This study demonstrates the potential of EPIC measurements for retrieving global aerosol height multiple times daily, which are essential for evaluating aerosol profile simulated in climate models and for better estimating aerosol radiative effects. ©2017. American Geophysical Union. All Rights Reserved."
"23571033500;56611366900;55674516400;56893048100;55653847500;56384601100;55268427500;57214207021;35265615300;","Anthropogenic pollution elevates the peak height of new particle formation from planetary boundary layer to lower free troposphere",2017,"10.1002/2017GL074553","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026450749&doi=10.1002%2f2017GL074553&partnerID=40&md5=f17c90feeeb69c72c1ece56a1b40c5bc","New particle formation (NPF) and subsequent growth are primary sources of atmospheric aerosol particles and cloud condensation nuclei. Previous studies have been conducted in relatively clean environments; investigation of NPF events over highly polluted megacities is still lacking. Here we show, based on a recent yearlong aircraft campaign conducted over Beijing, China, from April 2011 to June 2012, that NPF occurrence peaks in the lower free troposphere (LT), instead of planetary boundary layer (PBL), as most previous studies have found and that the distance of NPF peak to PBL top increases with increasing aerosol loading. Further analysis reveals that increased aerosols suppress NPF in PBL, but enhance NPF in LT due to a complex chain of aerosol-radiation-photochemistry interactions that affect both NPF sources and sinks. These findings shed new light on our understanding of NPF occurrence, NPF vertical distribution, and thus their effects on atmospheric photochemistry, clouds, and climate. ©2017. American Geophysical Union. All Rights Reserved."
"24168479200;57195235990;57195236002;57195236023;57205707345;56158622800;55087038900;","An improved hydrometeor detection method for millimeter-wavelength cloud radar",2017,"10.5194/acp-17-9035-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026441867&doi=10.5194%2facp-17-9035-2017&partnerID=40&md5=6f82981eff27d4a90eec4fb69797f087","A modified method with a new noise reduction scheme that can reduce the noise distribution to a narrow range is proposed to distinguish clouds and other hydrometeors from noise and recognize more features with weak signal in cloud radar observations. A spatial filter with central weighting, which is widely used in cloud radar hydrometeor detection algorithms, is also applied in our method to examine radar return for significant levels of signals. <q>Square clouds</q> were constructed to test our algorithm and the method used for the US Department of Energy Atmospheric Radiation Measurements Program millimeter-wavelength cloud radar. We also applied both the methods to 6 months of cloud radar observations at the Semi-Arid Climate and Environment Observatory of Lanzhou University and compared the results. It was found that our method has significant advantages in reducing the rates of both failed negative and false positive hydrometeor identifications in simulated clouds and recognizing clouds with weak signal from our cloud radar observations."
"57192954165;8964014100;57211681908;7004715270;57195100514;7005773698;","Automation and heat transfer characterization of immersion mode spectroscopy for analysis of ice nucleating particles",2017,"10.5194/amt-10-2613-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85025473354&doi=10.5194%2famt-10-2613-2017&partnerID=40&md5=7849a39de0539c631ee1875985ed54f0","Ice nucleating particles (INPs) influence cloud properties and can affect the overall precipitation efficiency. Developing a parameterization of INPs in global climate models has proven challenging. More INP measurements - including studies of their spatial distribution, sources and sinks, and fundamental freezing mechanisms - must be conducted in order to further improve INP parameterizations. In this paper, an immersion mode INP measurement technique is modified and automated using a software-controlled, real-time image stream designed to leverage optical changes of water droplets to detect freezing events. For the first time, heat transfer properties of the INP measurement technique are characterized using a finite-element-analysis-based heat transfer simulation to improve accuracy of INP freezing temperature measurement. The heat transfer simulation is proposed as a tool that could be used to explain the sources of bias in temperature measurements in INP measurement techniques and ultimately explain the observed discrepancies in measured INP freezing temperatures between different instruments. The simulation results show that a difference of +8.4 °C between the well base temperature and the headspace gas results in an up to 0.6 °C stratification of the aliquot, whereas a difference of +4.2 °C or less results in a thermally homogenous water volume within the error of the thermal probe, ±0.2 °C. The results also show that there is a strong temperature gradient in the immediate vicinity of the aliquot, such that without careful placement of temperature probes, or characterization of heat transfer properties of the water and cooling environment, INP measurements can be biased toward colder temperatures. Based on a modified immersion mode technique, the Automated Ice Spectrometer (AIS), measurements of the standard test dust illite NX are reported and compared against six other immersion mode droplet assay techniques featured in Hiranuma et al. (2015) that used wet suspensions. AIS measurements of illite NX INP freezing temperatures compare reasonably with others, falling within the 5 °C spread in reported spectra. The AIS as well as its characterization of heat transfer properties allows higher confidence in accuracy of freezing temperature measurement, allows higher throughput of sample analysis, and enables disentanglement of the effects of heat transfer rates on sample volumes from time dependence of ice nucleation. © 2017 Author(s)."
"8600097900;7202962414;6701606453;","A variational technique to estimate snowfall rate from coincident radar, snowflake, and fall-speed observations",2017,"10.5194/amt-10-2557-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85025151249&doi=10.5194%2famt-10-2557-2017&partnerID=40&md5=89943856a5d855e8c1c2bcb29c7ffbee","Estimates of snowfall rate as derived from radar reflectivities alone are non-unique. Different combinations of snowflake microphysical properties and particle fall speeds can conspire to produce nearly identical snowfall rates for given radar reflectivity signatures. Such ambiguities can result in retrieval uncertainties on the order of 100-200% for individual events. Here, we use observations of particle size distribution (PSD), fall speed, and snowflake habit from the Multi-Angle Snowflake Camera (MASC) to constrain estimates of snowfall derived from Ka-band ARM zenith radar (KAZR) measurements at the Atmospheric Radiation Measurement (ARM) North Slope Alaska (NSA) Climate Research Facility site at Barrow. MASC measurements of microphysical properties with uncertainties are introduced into a modified form of the optimal-estimation CloudSat snowfall algorithm (2C-SNOW-PROFILE) via the a priori guess and variance terms. Use of the MASC fall speed, MASC PSD, and CloudSat snow particle model as base assumptions resulted in retrieved total accumulations with a -18% difference relative to nearby National Weather Service (NWS) observations over five snow events. The average error was 36% for the individual events. Use of different but reasonable combinations of retrieval assumptions resulted in estimated snowfall accumulations with differences ranging from -64 to +122% for the same storm events. Retrieved snowfall rates were particularly sensitive to assumed fall speed and habit, suggesting that in situ measurements can help to constrain key snowfall retrieval uncertainties. More accurate knowledge of these properties dependent upon location and meteorological conditions should help refine and improve ground- and space-based radar estimates of snowfall."
"7003717604;7404087896;7201978222;7102242175;6506630170;16199172000;15021288100;","A climate-scale satellite record for carbon monoxide: The MOPITT Version 7 product",2017,"10.5194/amt-10-2533-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85025079242&doi=10.5194%2famt-10-2533-2017&partnerID=40&md5=3ff943a30798002ea4d168b40f3c4a7b","The MOPITT (Measurements of Pollution in the Troposphere) satellite instrument has been making observations of atmospheric carbon monoxide since 2000. Recent enhancements to the MOPITT retrieval algorithm have resulted in the release of the version 7 (V7) product. Improvements include (1) representation of growing atmospheric concentrations of N2O, (2) use of meteorological fields from the MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications) reanalysis for the entire MOPITT mission (instead of MERRA), (3) use of the MODIS (Moderate-Resolution Imaging Spectroradiometer) Collection 6 cloud mask product (instead of Collection 5), (4) a new strategy for radiance-bias correction and (5) an improved method for calibrating MOPITT's near-infrared (NIR) radiances. Statistical comparisons of V7 validation results with corresponding V6 results are presented, using aircraft in situ measurements as the reference. Clear improvements are demonstrated for V7 products with respect to overall retrieval biases, bias variability and bias drift uncertainty."
"57188699861;55705948900;14019100300;57191034805;56754613500;55487654100;7202041928;","Response of the global surface ozone distribution to Northern Hemisphere sea surface temperature changes: Implications for long-range transport",2017,"10.5194/acp-17-8771-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85025091685&doi=10.5194%2facp-17-8771-2017&partnerID=40&md5=01e693cef6f55a8c0d483df96b34936b","The response of surface ozone (O3) concentrations to basin-scale warming and cooling of Northern Hemisphere oceans is investigated using the Community Earth System Model (CESM). Idealized, spatially uniform sea surface temperature (SST) anomalies of ±1°C are individually superimposed onto the North Pacific, North Atlantic, and North Indian oceans. Our simulations suggest large seasonal and regional variability in surface O3 in response to SST anomalies, especially in the boreal summer. The responses of surface O3 associated with basin-scale SST warming and cooling have similar magnitude but are opposite in sign. Increasing the SST by 1°C in one of the oceans generally decreases the surface O3 concentrations from 1 to 5ppbv. With fixed emissions, SST increases in a specific ocean basin in the Northern Hemisphere tend to increase the summertime surface O3 concentrations over upwind regions, accompanied by a widespread reduction over downwind continents. We implement the integrated process rate (IPR) analysis in CESM and find that meteorological O3 transport in response to SST changes is the key process causing surface O3 perturbations in most cases. During the boreal summer, basin-scale SST warming facilitates the vertical transport of O3 to the surface over upwind regions while significantly reducing the vertical transport over downwind continents. This process, as confirmed by tagged CO-like tracers, indicates a considerable suppression of intercontinental O3 transport due to increased tropospheric stability at lower midlatitudes induced by SST changes. Conversely, the responses of chemical O3 production to regional SST warming can exert positive effects on surface O3 levels over highly polluted continents, except South Asia, where intensified cloud loading in response to North Indian SST warming depresses both the surface air temperature and solar radiation, and thus photochemical O3 production. Our findings indicate a robust linkage between basin-scale SST variability and continental surface O3 pollution, which should be considered in regional air quality management."
"57133136000;6701402110;","Benefits of improved municipal solid waste management on greenhouse gas reduction in Luangprabang, Laos",2017,"10.1080/09593330.2017.1301562","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015680346&doi=10.1080%2f09593330.2017.1301562&partnerID=40&md5=997e064f262d32d4568043b1c2e428ed","Climate change is a consequence of greenhouse gas emissions. Greenhouse gas (GHG) emissions from the waste sector contribute to 3% of total anthropogenic emissions. In this study, applicable solutions for municipal solid waste (MSW) management in Luangprabang (LPB) and Laos were examined. Material flow analysis of MSW was performed to estimate the amount of MSW generated in 2015. Approximately 29,419 tonnes of MSW is estimated for 2015. Unmanaged landfilling was the main disposal method, while MSW open burning was also practiced to some extent. The International Panel on Climate Change 2006 model and the Atmospheric Brown Clouds Emission Inventory Manual were used to estimate GHG emissions from existing MSW management, and total emissions are 33,889 tonnes/year carbon dioxide-equivalents (CO2-eq). Three scenarios were developed in order to reduce GHG emissions and environmental problems. Improvement of the MSW management by expanding MSW collection services, introducing composting and recycling, and avoiding open burning, can be considered as solutions to overcome the problems for LPB. The lowest GHG emissions are achieved in the scenario where composting and recycling are proposed, with the total GHG emissions reduction by 18,264 tonnes/year CO2-eq. © 2017 Informa UK Limited, trading as Taylor & Francis Group."
"56089348800;16475714800;","Competing effects of surface albedo and orographic elevated heating on regional climate",2017,"10.1002/2016GL072441","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021897313&doi=10.1002%2f2016GL072441&partnerID=40&md5=0b794147e856c9b0ba060bcae379cb14","All else being equal, a given atmospheric pressure level is thought to be warmer over a plateau than over surrounding nonelevated terrain because of orographic “elevated heating.” However, elevated surfaces are also typically brighter due to reduced vegetation and increased ice cover. Here we assess the degree to which surface albedo compensates for orographic elevated heating. We confirm that land surface albedo generally increases with surface elevation in observations. Using a cloud system-resolving model, we show that increased surface albedo strongly compensates for orographic elevated heating in radiative-convective equilibrium. A nonelevated surface with the albedo of modern India would enter a runaway greenhouse regime without ventilation by monsoonal winds, while a surface with the albedo and elevation of Tibet would achieve a cooler radiative-convective equilibrium. Surface albedo changes may thus be just as important as surface elevation changes for the evolution of low-latitude regional climate throughout Earth's history. ©2017. American Geophysical Union. All Rights Reserved."
"56975628900;39962577400;57197980087;6701382296;57194794058;35224480500;","Sulfate production by reactive bromine: Implications for the global sulfur and reactive bromine budgets",2017,"10.1002/2017GL073812","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022345001&doi=10.1002%2f2017GL073812&partnerID=40&md5=9b701622a73712c8c9901c67a66b4608","Sulfur and reactive bromine (Bry) play important roles in tropospheric chemistry and the global radiation budget. The oxidation of dissolved SO2 (S(IV)) by HOBr increases sulfate aerosol abundance and may also impact the Bry budget, but is generally not included in global climate and chemistry models. In this study, we implement HOBr + S(IV) reactions into the GEOS-Chem global chemical transport model and evaluate the global impacts on both sulfur and Bry budgets. Modeled HOBr mixing ratios on the order of 0.1–1.0 parts per trillion (ppt) lead to HOBr + S(IV) contributing to 8% of global sulfate production and up to 45% over some tropical ocean regions with high HOBr mixing ratios (0.6–0.9 ppt). Inclusion of HOBr + S(IV) in the model leads to a global Bry decrease of 50%, initiated by the decrease in bromide recycling in cloud droplets. Observations of HOBr are necessary to better understand the role of HOBr + S(IV) in tropospheric sulfur and Bry cycles. ©2017. American Geophysical Union. All Rights Reserved."
"8586435700;7202174228;56283402900;","Update of the Polar SWIFT model for polar stratospheric ozone loss (Polar SWIFT version 2)",2017,"10.5194/gmd-10-2671-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85024127236&doi=10.5194%2fgmd-10-2671-2017&partnerID=40&md5=2a2d6c10db59346ae88d7f19e5db8b25","The Polar SWIFT model is a fast scheme for calculating the chemistry of stratospheric ozone depletion in polar winter. It is intended for use in global climate models (GCMs) and Earth system models (ESMs) to enable the simulation of mutual interactions between the ozone layer and climate. To date, climate models often use prescribed ozone fields, since a full stratospheric chemistry scheme is computationally very expensive. Polar SWIFT is based on a set of coupled differential equations, which simulate the polar vortex-averaged mixing ratios of the key species involved in polar ozone depletion on a given vertical level. These species are O3, chemically active chlorine (ClOx), HCl, ClONO2 and HNO3. The only external input parameters that drive the model are the fraction of the polar vortex in sunlight and the fraction of the polar vortex below the temperatures necessary for the formation of polar stratospheric clouds. Here, we present an update of the Polar SWIFT model introducing several improvements over the original model formulation. In particular, the model is now trained on vortex-averaged reaction rates of the ATLAS Chemistry and Transport Model, which enables a detailed look at individual processes and an independent validation of the different parameterizations contained in the differential equations. The training of the original Polar SWIFT model was based on fitting complete model runs to satellite observations and did not allow for this. A revised formulation of the system of differential equations is developed, which closely fits vortex-averaged reaction rates from ATLAS that represent the main chemical processes influencing ozone. In addition, a parameterization for the HNO3 change by denitrification is included. The rates of change of the concentrations of the chemical species of the Polar SWIFT model are purely chemical rates of change in the new version, whereas in the original Polar SWIFT model, they included a transport effect caused by the original training on satellite data. Hence, the new version allows for an implementation into climate models in combination with an existing stratospheric transport scheme. Finally, the model is now formulated on several vertical levels encompassing the vertical range in which polar ozone depletion is observed. The results of the Polar SWIFT model are validated with independent Microwave Limb Sounder (MLS) satellite observations and output from the original detailed chemistry model of ATLAS. © Author(s) 2017."
"57194829903;8656775300;6701735773;55352134000;","Seasonal cycle of desert aerosols in western Africa: Analysis of the coastal transition with passive and active sensors",2017,"10.5194/acp-17-8395-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85023182029&doi=10.5194%2facp-17-8395-2017&partnerID=40&md5=a2a37d1a8f01339a3a633c80ff994676","The impact of desert aerosols on climate, atmospheric processes, and the environment is still debated in the scientific community. The extent of their influence remains to be determined and particularly requires a better understanding of the variability of their distribution. In this work, we studied the variability of these aerosols in western Africa using different types of satellite observations. SeaWiFS (Sea-Viewing Wide Field-of-View Sensor) and OMI (Ozone Monitoring Instrument) data have been used to characterize the spatial distribution of mineral aerosols from their optical and physical properties over the period 2005-2010. In particular, we focused on the variability of the transition between continental western African and the eastern Atlantic Ocean. Data provided by the lidar scrolling CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) onboard the satellite CALIPSO (Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations) for the period 2007-2013 were then used to assess the seasonal variability of the vertical distribution of desert aerosols. We first obtained a good representation of aerosol optical depth (AOD) and single-scattering albedo (SSA) from the satellites SeaWiFS and OMI, respectively, in comparison with AERONET estimates, both above the continent and the ocean. Dust occurrence frequency is higher in spring and boreal summer. In spring, the highest occurrences are located between the surface and 3km above sea level, while in summer the highest occurrences are between 2 and 5km altitude. The vertical distribution given by CALIOP also highlights an abrupt change at the coast from spring to fall with a layer of desert aerosols confined in an atmospheric layer uplifted from the surface of the ocean. This uplift of the aerosol layer above the ocean contrasts with the winter season during which mineral aerosols are confined in the atmospheric boundary layer. Radiosondes at Dakar Weather Station (17.5°W, 14.74°N) provide basic thermodynamic variables which partially give a causal relationship between the layering of the atmospheric circulation over western Africa and their aerosol contents throughout the year. A SSA increase is observed in winter and spring at the transition between the continent and the ocean. The analysis of mean NCEP (National Centers for Environmental Prediction) winds at 925hPa between 2000 and 2012 suggest a significant contribution of coastal sand sources from Mauritania in winter which would increase SSA over the ocean. © Author(s) 2017."
"37111900500;55749785900;56597778200;6701530981;55541379500;6701410329;9233045100;","The MSG-SEVIRI-based cloud property data record CLAAS-2",2017,"10.5194/essd-9-415-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020254561&doi=10.5194%2fessd-9-415-2017&partnerID=40&md5=253297377c341715a8ded14c2e6dabdc","Clouds play a central role in the Earth's atmosphere, and satellite observations are crucial for monitoring clouds and understanding their impact on the energy budget and water cycle. Within the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Satellite Application Facility on Climate Monitoring (CM SAF), a new cloud property data record was derived from geostationary Meteosat Spinning Enhanced Visible and Infrared Imager (SEVIRI) measurements for the time frame 2004-2015. The resulting CLAAS-2 (CLoud property dAtAset using SEVIRI, Edition 2) data record is publicly available via the CM SAF website (https://doi.org/10.5676/EUM-SAF-CM/CLAAS/V002). In this paper we present an extensive evaluation of the CLAAS-2 cloud products, which include cloud fractional coverage, thermodynamic phase, cloud top properties, liquid/ice cloud water path and corresponding optical thickness and particle effective radius. Data validation and comparisons were performed on both level 2 (native SEVIRI grid and repeat cycle) and level 3 (daily and monthly averages and histograms) with reference datasets derived from lidar, microwave and passive imager measurements. The evaluation results show very good overall agreement with matching spatial distributions and temporal variability and small biases attributed mainly to differences in sensor characteristics, retrieval approaches, spatial and temporal samplings and viewing geometries. No major discrepancies were found. Underpinned by the good evaluation results, CLAAS-2 demonstrates that it is fit for the envisaged applications, such as process studies of the diurnal cycle of clouds and the evaluation of regional climate models. The data record is planned to be extended and updated in the future. © 2017 Author(s)."
"27467537200;37090362900;6603749963;56379892200;56284543100;9636594900;7004942632;","Emission metrics for quantifying regional climate impacts of aviation",2017,"10.5194/esd-8-547-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85023196288&doi=10.5194%2fesd-8-547-2017&partnerID=40&md5=46c6b958eb2ee0c72cdc570f6744c023","This study examines the impacts of emissions from aviation in six source regions on global and regional temperatures. We consider the NOx-induced impacts on ozone and methane, aerosols and contrail-cirrus formation and calculate the global and regional emission metrics global warming potential (GWP), global temperature change potential (GTP) and absolute regional temperature change potential (ARTP). The GWPs and GTPs vary by a factor of 2-4 between source regions. We find the highest aviation aerosol metric values for South Asian emissions, while contrail-cirrus metrics are higher for Europe and North America, where contrail formation is prevalent, and South America plus Africa, where the optical depth is large once contrails form. The ARTP illustrate important differences in the latitudinal patterns of radiative forcing (RF) and temperature response: the temperature response in a given latitude band can be considerably stronger than suggested by the RF in that band, also emphasizing the importance of large-scale circulation impacts. To place our metrics in context, we quantify temperature change in four broad latitude bands following 1 year of emissions from present-day aviation, including CO2. Aviation over North America and Europe causes the largest net warming impact in all latitude bands, reflecting the higher air traffic activity in these regions. Contrail cirrus gives the largest warming contribution in the short term, but remain important at about 15% of the CO2 impact in several regions even after 100 years. Our results also illustrate both the short- and long-term impacts of CO2: while CO2 becomes dominant on longer timescales, it also gives a notable warming contribution already 20 years after the emission. Our emission metrics can be further used to estimate regional temperature change under alternative aviation emission scenarios. A first evaluation of the ARTP in the context of aviation suggests that further work to account for vertical sensitivities in the relationship between RF and temperature response would be valuable for further use of the concept. © 2017 Author(s)."
"7404142321;13402835300;","A multi-diagnostic approach to cloud evaluation",2017,"10.5194/gmd-10-2547-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017510994&doi=10.5194%2fgmd-10-2547-2017&partnerID=40&md5=a818428709ef894691e6f9ad8abd13cf","Most studies evaluating cloud in general circulation models present new diagnostic techniques or observational datasets, or apply a limited set of existing diagnostics to a number of models. In this study, we use a range of diagnostic techniques and observational datasets to provide a thorough evaluation of cloud, such as might be carried out during a model development process. The methodology is illustrated by analysing two configurations of the Met Office Unified Model - the currently operational configuration at the time of undertaking the study (Global Atmosphere 6, GA6), and the configuration which will underpin the United Kingdom's Earth System Model for CMIP6 (Coupled Model Intercomparison Project 6; GA7). By undertaking a more comprehensive analysis which includes compositing techniques, comparing against a set of quite different observational instruments and evaluating the model across a range of timescales, the risks of drawing the wrong conclusions due to compensating model errors are minimized and a more accurate overall picture of model performance can be drawn. Overall the two configurations analysed perform well, especially in terms of cloud amount. GA6 has excessive thin cirrus which is removed in GA7. The primary remaining errors in both configurations are the in-cloud albedos which are too high in most Northern Hemisphere cloud types and sub-tropical stratocumulus, whilst the stratocumulus on the cold-air side of Southern Hemisphere cyclones has in-cloud albedos which are too low. © Author(s) 2017."
"55985276100;57193955604;","Assessing and mapping energy biomass distribution using a UAV in Finland",2017,"10.1080/17597269.2017.1302663","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017587649&doi=10.1080%2f17597269.2017.1302663&partnerID=40&md5=c15fe1ae8346d2168e4aa2c138671208","The increasing need to reduce greenhouse gas emissions to slow down climate change requires more effective and versatile methods for producing energy. In Finland, common reed and forest biomass are used for energy production. There are efforts to increase the utilisation of renewable energy resources. The potential intensification of renewables utilisation may result in changes to the landscape's structure and functions. The objective of this study was to develop a method for energy biomass mapping in landscapes using high-resolution remote sensing data from an unmanned aerial vehicle (UAV). The images were obtained from UAVs in Ojalahti, Lipperi, Finland, and a point cloud was calculated from the overlapped images. Individual plants were automatically identified using object-oriented image processing. The size of the individual plants was measured from orthophotographs and the point cloud. It was possible to develop an accurate three-dimensional model of the biomass distribution within the landscape. The error in height measurements of common reed plants and forest trees was 0.044 m. The root-mean-square deviation in common reed biomass measurements using the UAV data obtained was 0.096 m3. The new method developed in this study could be used as a cost-effective solution for common reed biomass resources assessment. This would allow for the mobilisation of common reed biomass for sustainable energy production. © 2017 Informa UK Limited, trading as Taylor & Francis Group."
"55975284200;18434662400;14059243100;57196398557;55438286600;","Simulation of the regional climatic effect of irrigation over the Yellow River Basin",2017,"10.1080/16742834.2017.1313681","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044473655&doi=10.1080%2f16742834.2017.1313681&partnerID=40&md5=db760426bc0f83e75552f40ed1b668d9","In this study, the authors developed a new irrigation scheme based on the Noah land surface model, and then coupled it with the Weather Research and Forecasting regional climate model. Two simulations (with and without irrigation) were conducted over the Yellow River basin for the period April to October 2000–2010. The results indicated that the WRF model is able to successfully capture the spatial pattern and seasonal changes in observed temperature and precipitation over the Yellow River basin. When irrigation was induced, the mean surface air temperature at 2 m (T2m) decreased by 0.1–0.4 K, and there was a correspond increase (decrease) in latent (sensible) heat flux over the irrigated areas, wherein the increase (decrease) reached more than 10 W m−2 over the largest irrigated areas. The cooling effect was consistent with the changes in evapotranspiration and heat fluxes due to irrigation. The changes in lifting condensation level and planetary boundary layer height led to a greater probability of cloud formation and bore a close association with surface fluxes and soil moisture, which then impacted the spatial distribution of T2m and precipitation. © 2017, © 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group."
"23987289400;35593636200;6506180220;7801611677;7202088827;15072064200;7003798647;7006084942;","Pan-Arctic aerosol number size distributions: Seasonality and transport patterns",2017,"10.5194/acp-17-8101-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022208377&doi=10.5194%2facp-17-8101-2017&partnerID=40&md5=cd4a4bd82ad526164f0c5f1e9e2d8b55","The Arctic environment has an amplified response to global climatic change. It is sensitive to human activities that mostly take place elsewhere. For this study, a multi-year set of observed aerosol number size distributions in the diameter range of 10 to 500nm from five sites around the Arctic Ocean (Alert, Villum Research Station - Station Nord, Zeppelin, Tiksi and Barrow) was assembled and analysed. A cluster analysis of the aerosol number size distributions revealed four distinct distributions. Together with Lagrangian air parcel back-trajectories, they were used to link the observed aerosol number size distributions with a variety of transport regimes. This analysis yields insight into aerosol dynamics, transport and removal processes, on both an intra- and an inter-monthly scale. For instance, the relative occurrence of aerosol number size distributions that indicate new particle formation (NPF) event is near zero during the dark months, increases gradually to ∼ 40% from spring to summer, and then collapses in autumn. Also, the likelihood of Arctic haze aerosols is minimal in summer and peaks in April at all sites. The residence time of accumulation-mode particles in the Arctic troposphere is typically long enough to allow tracking them back to their source regions. Air flow that passes at low altitude over central Siberia and western Russia is associated with relatively high concentrations of accumulation-mode particles (Nacc) at all five sites - often above 150cm-3. There are also indications of air descending into the Arctic boundary layer after transport from lower latitudes. The analysis of the back-trajectories together with the meteorological fields along them indicates that the main driver of the Arctic annual cycle of Nacc, on the larger scale, is when atmospheric transport covers the source regions for these particles in the 10-day period preceding the observations in the Arctic. The scavenging of these particles by precipitation is shown to be important on a regional scale and it is most active in summer. Cloud processing is an additional factor that enhances the Nacc annual cycle. There are some consistent differences between the sites that are beyond the year-to-year variability. They are the result of differences in the proximity to the aerosol source regions and to the Arctic Ocean sea-ice edge, as well as in the exposure to free-tropospheric air and in precipitation patterns - to mention a few. Hence, for most purposes, aerosol observations from a single Arctic site cannot represent the entire Arctic region. Therefore, the results presented here are a powerful observational benchmark for evaluation of detailed climate and air chemistry modelling studies of aerosols throughout the vast Arctic region."
"7402284525;7005275092;9434771700;6603907571;35568718600;","A radiative transfer module for calculating photolysis rates and solar heating in climate models: Solar-J v7.5",2017,"10.5194/gmd-10-2525-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021766223&doi=10.5194%2fgmd-10-2525-2017&partnerID=40&md5=efbf7945afbda37ff55cfe42da285146","Solar-J is a comprehensive radiative transfer model for the solar spectrum that addresses the needs of both solar heating and photochemistry in Earth system models. Solar-J is a spectral extension of Cloud-J, a standard in many chemical models that calculates photolysis rates in the 0.18-0.8 μm region. The Cloud-J core consists of an eight-stream scattering, plane-parallel radiative transfer solver with corrections for sphericity. Cloud-J uses cloud quadrature to accurately average over correlated cloud layers. It uses the scattering phase function of aerosols and clouds expanded to eighth order and thus avoids isotropic-equivalent approximations prevalent in most solar heating codes. The spectral extension from 0.8 to 12 μm enables calculation of both scattered and absorbed sunlight and thus aerosol direct radiative effects and heating rates throughout the Earth's atmosphere. The Solar-J extension adopts the correlated-k gas absorption bins, primarily water vapor, from the shortwave Rapid Radiative Transfer Model for general circulation model (GCM) applications (RRTMG-SW). Solar-J successfully matches RRTMG-SW's tropospheric heating profile in a clear-sky, aerosol-free, tropical atmosphere. We compare both codes in cloudy atmospheres with a liquid-water stratus cloud and an ice-crystal cirrus cloud. For the stratus cloud, both models use the same physical properties, and we find a systematic low bias of about 3 % in planetary albedo across all solar zenith angles caused by RRTMG-SW's two-stream scattering. Discrepancies with the cirrus cloud using any of RRTMG-SW's three different parameterizations are as large as about 20-40 % depending on the solar zenith angles and occur throughout the atmosphere. Effectively, Solar-J has combined the best components of RRTMG-SW and Cloud-J to build a high-fidelity module for the scattering and absorption of sunlight in the Earth's atmosphere, for which the three major components - wavelength integration, scattering, and averaging over cloud fields - all have comparably small errors. More accurate solutions with Solar-J come with increased computational costs, about 5 times that of RRTMG-SW for a single atmosphere. There are options for reduced costs or computational acceleration that would bring costs down while maintaining improved fidelity and balanced errors. © Author(s) 2017."
"51864663400;23991212200;7004479957;6602878057;6701346974;","Toward low-cloud-permitting cloud superparameterization with explicit boundary layer turbulence",2017,"10.1002/2017MS000968","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021736685&doi=10.1002%2f2017MS000968&partnerID=40&md5=0f4ca4b79b8267d9345d061194bf95d3","Systematic biases in the representation of boundary layer (BL) clouds are a leading source of uncertainty in climate projections. A variation on superparameterization (SP) called “ultraparameterization” (UP) is developed, in which the grid spacing of the cloud-resolving models (CRMs) is fine enough (250 × 20 m) to explicitly capture the BL turbulence, associated clouds, and entrainment in a global climate model capable of multiyear simulations. UP is implemented within the Community Atmosphere Model using 2° resolution (∼14,000 embedded CRMs) with one-moment microphysics. By using a small domain and mean-state acceleration, UP is computationally feasible today and promising for exascale computers. Short-duration global UP hindcasts are compared with SP and satellite observations of top-of-atmosphere radiation and cloud vertical structure. The most encouraging improvement is a deeper BL and more realistic vertical structure of subtropical stratocumulus (Sc) clouds, due to stronger vertical eddy motions that promote entrainment. Results from 90 day integrations show climatological errors that are competitive with SP, with a significant improvement in the diurnal cycle of offshore Sc liquid water. Ongoing concerns with the current UP implementation include a dim bias for near-coastal Sc that also occurs less prominently in SP and a bright bias over tropical continental deep convection zones. Nevertheless, UP makes global eddy-permitting simulation a feasible and interesting alternative to conventionally parameterized GCMs or SP-GCMs with turbulence parameterizations for studying BL cloud-climate and cloud-aerosol feedback. © 2017. The Authors."
"57033686900;56458012600;7202145115;","Low-cloud, boundary layer, and sea ice interactions over the Southern Ocean during winter",2017,"10.1175/JCLI-D-16-0483.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020131402&doi=10.1175%2fJCLI-D-16-0483.1&partnerID=40&md5=2c258cc73ec10c90fb5b97a0b7823422","During austral winter, a sharp contrast in low-cloud fraction and boundary layer structure across the Antarctic sea ice edge is seen in ship-based measurements and in active satellite retrievals from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), which provide an unprecedented view of polar clouds during winter. Sea ice inhibits heat and moisture transport from the ocean to the atmosphere, and, as a result, the boundary layer is cold, stable, and clear over sea ice and warm, moist, well mixed, and cloudy over open water. The mean low-cloud fraction observed by CALIPSO is roughly 0.7 over open water and 0.4-0.5 over sea ice, and the low-cloud layer is deeper over open water. Low-level winds in excess of 10 m s-1 are common over sea ice. Cold advection off of the sea ice pack causes enhanced low-cloud fraction over open water, and thus an enhanced longwave cloud radiative effect at the surface. Quantitative estimates of the surface longwave cloud radiative effect contributed by low clouds are presented. Finally, 10 state-of-the-art global climate models with satellite simulators are compared to observations. Near the sea ice edge, 7 out of 10 models simulate cloudier conditions over open water than over sea ice. Most models also underestimate low-cloud fraction both over sea ice and over open water. © 2017 American Meteorological Society."
"57195638103;16480992300;6507296473;7103204204;6603868770;","Characterization of Water Vapor and Clouds during the Next-Generation Aircraft Remote Sensing for Validation (NARVAL) South Studies",2017,"10.1109/JSTARS.2017.2687943","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029423862&doi=10.1109%2fJSTARS.2017.2687943&partnerID=40&md5=a87e222ef9b0b336578afe7ae4883598","Shallow trade wind clouds pose one of the largest uncertainties in climate models. Due to the difficulties in assessing these clouds with routine observations the next-generation aircraft remote-sensing for validation campaign with the German High Altitude and LOng range research aircraft (HALO) took place in December 2013. Here we take advantage of the synergy of the HALO active and passive microwave package as well as spectrally resolved solar radiation (SR) measured by HALO-SR to characterize shallow clouds in the Caribbean. Based on a cloud mask developed from HALO-SR, about 12 000 cloudy profiles within \sim 4100 individual clouds could be detected with about 70\,\% of them having a length of less than 2 km. Corresponding measurements with passive microwave measurements reveal that these small clouds also contain little water with 36% of the clouds showing a liquid water path (LWP) of less than \text{50 g}\cdot \text{m}^{-2}. We show that these small and thin clouds are difficult to characterize with satellite observations by the special sensor microwave imager/sounder due to its coarse resolution. Moderate imaging spectroradiometer measurements are able to identify the smaller clouds but suffer in terms of LWP when clouds start precipitating, which is the case for about 7% of the clouds as detected by the airborne 35 GHz radar. &copy; 2008-2012 IEEE."
"57195926196;57195933620;57195927856;57195929616;","A comprehensive evaluation of regional water safety systems based on a similarity cloud model",2017,"10.2166/wst.2017.235","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030169627&doi=10.2166%2fwst.2017.235&partnerID=40&md5=0385a17c8ac2e61dcca7ac9b66135513","Regional water safety systems are affected by social, economic, ecological, hydrological and other factors, and their effects are complicated and variable. Studying water safety systems is crucial to promoting the coordinated development of regional water safety systems and anthropogenic processes. Thus, a similarity cloud model is developed to simulate the evolution mechanisms of fuzzy and complex regional systems of water security and overcome the uncertainty that is associated with the indices that are used in water safety index systems. This cloud generator is used to reciprocally transform a qualitative cloud image with a quantitative cloud characteristic value, and the stochastic weight assignment method is used to determine the weight of the evaluation indices. The results of case studies show that Jiansanjiang's water safety systems were in a safe state in 2002-2011, but the water safety systems in the arid area of Yinchuan City were in a dangerous state in 2006-2007 because of climate factors and a lack of effective water and soil resource protection. The experimental results are consistent with the research subjects' actual situations, and the proposed model provides a tool for decision makers to better understand the security issues that are associated with regional water safety systems. © 2017 IWA Publishing."
"36941575300;8549269500;","CloudSat observations of multi layered clouds across the globe",2017,"10.1007/s00382-016-3345-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84986300653&doi=10.1007%2fs00382-016-3345-7&partnerID=40&md5=6d32fcfeeaa57788671b5a0f3b00fa2d","Vertically resolved multi-layer cloud distributions over the globe using 4 years of CloudSat/CALIPSO observations during 2007–2010 are discussed. The quantitative information on the frequency of occurrence of one- to five-layered clouds across the globe is established, which are of immense importance from the global climate standpoint. After segregating the CloudSat observations into different seasons, the 4 years of mean global maps of frequency of occurrence of one to five-layered clouds are discussed in details. These global maps provide much needed quantification of vertically resolved multi-layer clouds by revealing when and where the frequency of occurrence of multi-layer clouds are maximum including the number of layers. On an average, it is observed that over the globe one-, two-, three-, four- and five-layer clouds occur 53, 20, 3.5, 0.4 and 0.04 % of the time respectively. High fraction of single layer clouds is observed over the descending limbs of Hadley cell where relatively large lower tropospheric stability is found. The regions where multi-layer clouds are more frequent are identified and discussed along with large scale circulation. Apart from quantifying the frequency of occurrence of multi-layer clouds, the latitudinal distribution of zonal mean occurrence of cloud base and top altitudes of each cloud layer is constructed for boreal winter and summer. These analyses provide the cloud base and top altitudes of one to five-layered clouds, which are important to understand the vertical structure of the multi-layered clouds. The significance of the present study lies in establishing the global distribution of vertically resolved multi-layer clouds and the role of large-scale dynamics in controlling their distribution for the first time. © 2016, Springer-Verlag Berlin Heidelberg."
"6602611904;35203227000;36968719000;57204335589;6603823606;","An advanced stochastic weather generator for simulating 2-D high-resolution climate variables",2017,"10.1002/2016MS000854","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022194381&doi=10.1002%2f2016MS000854&partnerID=40&md5=437a3ab803eaf14e2f0cdfbd01d28e26","A new stochastic weather generator, Advanced WEather GENerator for a two-dimensional grid (AWE-GEN-2d) is presented. The model combines physical and stochastic approaches to simulate key meteorological variables at high spatial and temporal resolution: 2 km × 2 km and 5 min for precipitation and cloud cover and 100 m × 100 m and 1 h for near-surface air temperature, solar radiation, vapor pressure, atmospheric pressure, and near-surface wind. The model requires spatially distributed data for the calibration process, which can nowadays be obtained by remote sensing devices (weather radar and satellites), reanalysis data sets and ground stations. AWE-GEN-2d is parsimonious in terms of computational demand and therefore is particularly suitable for studies where exploring internal climatic variability at multiple spatial and temporal scales is fundamental. Applications of the model include models of environmental systems, such as hydrological and geomorphological models, where high-resolution spatial and temporal meteorological forcing is crucial. The weather generator was calibrated and validated for the Engelberg region, an area with complex topography in the Swiss Alps. Model test shows that the climate variables are generated by AWE-GEN-2d with a level of accuracy that is sufficient for many practical applications. © 2017. The Authors."
"56167253200;57195482669;8247130000;6602433671;","Potential Distribution of Mountain Cloud Forest in Michoacán, Mexico: Prioritization for Conservation in the Context of Landscape Connectivity",2017,"10.1007/s00267-017-0871-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017646319&doi=10.1007%2fs00267-017-0871-y&partnerID=40&md5=16cf639af265e02cfbe5e286e83e6c58","Landscape connectivity is essential in biodiversity conservation because of its ability to reduce the effect of habitat fragmentation; furthermore is a key property in adapting to climate change. Potential distribution models and landscape connectivity studies have increased with regard to their utility to prioritizing areas for conservation. The objective of this study was to model the potential distribution of Mountain cloud forests in the Transversal Volcanic System, Michoacán and to analyze the role of these areas in maintaining landscape connectivity. Potential distribution was modeled for the Mountain cloud forests based on the maximum entropy approach using 95 occurrence points and 17 ecological variables at 30 m spatial resolution. Potential connectivity was then evaluated by using a probability of connectivity index based on graph theory. The percentage of variation (dPCk) was used to identify the individual contribution of each potential area of Mountain cloud forests in overall connectivity. The different ways in which the potential areas of Mountain cloud forests can contribute to connectivity were evaluated by using the three fractions derived from dPCk (dPCintrak, dPCfluxk, and dPCconnectork). We determined that 37,567 ha of the TVSMich are optimal for the presence of Mountain cloud forests. The contribution of said area in the maintenance of connectivity was low. The conservation of Mountain cloud forests is indispensable, however, in providing or receiving dispersal flows through TVSMich because of its role as a connector element between another habitat types. The knowledge of the potential capacity of Mountain cloud forests to promote structural and functional landscape connectivity is key in the prioritization of conservation areas. © 2017, Springer Science+Business Media New York."
"55628587967;6507400558;55550388400;34870277200;7004978125;","Implementation and calibration of a stochastic multicloud convective parameterization in the NCEP Climate Forecast System (CFSv2)",2017,"10.1002/2017MS001014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027844288&doi=10.1002%2f2017MS001014&partnerID=40&md5=414d675bd1f64cbb042920104bc80295","A comparative analysis of fourteen 5 year long climate simulations produced by the National Centers for Environmental Predictions (NCEP) Climate Forecast System version 2 (CFSv2), in which a stochastic multicloud (SMCM) cumulus parameterization is implemented, is presented here. These 5 year runs are made with different sets of parameters in order to figure out the best model configuration based on a suite of state-of-the-art metrics. This analysis is also a systematic attempt to understand the model sensitivity to the SMCM parameters. The model is found to be resilient to minor changes in the parameters used implying robustness of the SMCM formulation. The model is found to be most sensitive to the midtropospheric dryness parameter (MTD) and to the stratiform cloud decay timescale (τ30). MTD is more effective in controlling the global mean precipitation and its distribution while τ30 has more effect on the organization of convection as noticed in the simulation of the Madden-Julian oscillation (MJO). This is consistent with the fact that in the SMCM formulation, midtropospheric humidity controls the deepening of convection and stratiform clouds control the backward tilt of tropospheric heating and the strength of unsaturated downdrafts which cool and dry the boundary layer and trigger the propagation of organized convection. Many other studies have also found midtropospheric humidity to be a key factor in the capacity of a global climate model to simulate organized convection on the synoptic and intraseasonal scales. © 2017. The Authors."
"22939192200;36118090300;57203012560;56224155200;","Cloud radiative effects and changes simulated by the Coupled Model Intercomparison Project Phase 5 models",2017,"10.1007/s00376-017-6089-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020420925&doi=10.1007%2fs00376-017-6089-3&partnerID=40&md5=59d5b31d0171e62e17d5381c8183833b","Using 32 CMIP5 (Coupled Model Intercomparison Project Phase 5) models, this study examines the veracity in the simulation of cloud amount and their radiative effects (CREs) in the historical run driven by observed external radiative forcing for 1850–2005, and their future changes in the RCP (Representative Concentration Pathway) 4.5 scenario runs for 2006–2100. Validation metrics for the historical run are designed to examine the accuracy in the representation of spatial patterns for climatological mean, and annual and interannual variations of clouds and CREs. The models show large spread in the simulation of cloud amounts, specifically in the low cloud amount. The observed relationship between cloud amount and the controlling large-scale environment are also reproduced diversely by various models. Based on the validation metrics, four models—ACCESS1.0, ACCESS1.3, HadGEM2-CC, and HadGEM2-ES—are selected as best models, and the average of the four models performs more skillfully than the multimodel ensemble average. All models project global-mean SST warming at the increase of the greenhouse gases, but the magnitude varies across the simulations between 1 and 2 K, which is largely attributable to the difference in the change of cloud amount and distribution. The models that simulate more SST warming show a greater increase in the net CRE due to reduced low cloud and increased incoming shortwave radiation, particularly over the regions of marine boundary layer in the subtropics. Selected best-performing models project a significant reduction in global-mean cloud amount of about −0.99% K−1 and net radiative warming of 0.46 W m−2 K−1, suggesting a role of positive feedback to global warming. © 2017, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag GmbH Germany."
"55731064200;57194595597;57194588116;55831305300;","Bjerknes compensation in meridional heat transport under freshwater forcing and the role of climate feedback",2017,"10.1175/JCLI-D-16-0824.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021129057&doi=10.1175%2fJCLI-D-16-0824.1&partnerID=40&md5=5072fcd7637ced1d8261c223692d98ae","Using a coupled Earth climate model, freshwater forcing experiments are performed to study the Bjerknes compensation (BJC) between meridional atmosphere heat transport (AHT) and meridional ocean heat transport (OHT). Freshwater hosing in the North Atlantic weakens the Atlantic meridional overturning circulation (AMOC) and thus reduces the northward OHT in the Atlantic significantly, leading to a cooling (warming) in the surface layer in the Northern (Southern) Hemisphere. This results in an enhanced Hadley cell and northward AHT. Meanwhile, the OHT in the Indo-Pacific is increased in response to the Hadley cell change, partially offsetting the reduced OHT in the Atlantic. Two compensations occur here: compensation between theAHTand the Atlantic OHT, and that between the Indo-PacificOHTand the Atlantic OHT. The AHT change undercompensates the OHT change by about 60% in the extratropics, while the former overcompensates the latter by about 30% in the tropics due to the Indo-Pacific change. The BJC can be understood from the viewpoint of large-scale circulation change. However, the intrinsic mechanism of BJC is related to the climate feedback of the Earth system. The authors' coupled model experiments confirm that the occurrence of BJC is an intrinsic requirement of local energy balance, and local climate feedback determines the extent of BJC, consistent with previous theoretical results. Even during the transient period of climate change, the BJC is well established when the ocean heat storage is slowly varying and its change is much weaker than the net local heat flux change at the ocean surface. The BJC can be deduced from the local climate feedback. Under the freshwater forcing, the overcompensation in the tropics is mainly caused by the positive longwave feedback related to clouds, and the undercompensation in the extratropics is due to the negative longwave feedback related to surface temperature change. Different dominant feedbacks determine different BJC scenarios in different regions, which are in essence constrained by local energy balance. © 2017 American Meteorological Society."
"56237449000;6701481007;57190126006;57210222492;7202962414;6701606453;","Evaluation of Antarctic snowfall in global meteorological reanalyses",2017,"10.1016/j.atmosres.2017.02.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014319222&doi=10.1016%2fj.atmosres.2017.02.015&partnerID=40&md5=ee56dbb0eaf87693387cb535901a23d7","Recent precipitation observations provided by CloudSat are used to evaluate the ability of various meteorological analyses and reanalyses to reproduce Antarctic snowfall. The performance of the ECMWF Interim Re-Analysis (ERA Interim), the Climate Forecast System Reanalysis (CFSR), the Japanese 55-year Reanalysis (JRA55), the Modern Era Retrospective-Analysis for Research and Application (MERRA), and the Modern Era Retrospective-Analysis for Research and Application 2 (MERRA-2), as well as ECMWF operational analyses are compared over the 2007–2010 period. The mean snowfall rate over Antarctica north of 82 °S simulated by the reanalyses between 2007 and 2010 ranges from 165 to 225 mm per year, while CloudSat observations indicate a value of 172 mm per year. ERA Interim produces the closest match to the observed snowfall rate, but all the reanalyses reproduce well the seasonal and interannual variability of Antarctic snowfall reported in CloudSat observations. © 2017"
"57216494536;36816230300;55240576300;6701790782;36909438300;54792503800;57211236643;","Mapping vegetation heights in China using slope correction ICESat data, SRTM, MODIS-derived and climate data",2017,"10.1016/j.isprsjprs.2017.04.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019259392&doi=10.1016%2fj.isprsjprs.2017.04.020&partnerID=40&md5=cb1bab10f9afd635b674ee1669753d96","Vegetation height is an important parameter for biomass assessment and vegetation classification. However, vegetation height data over large areas are difficult to obtain. The existing vegetation height data derived from the Ice, Cloud and land Elevation Satellite (ICESat) data only include laser footprints in relatively flat forest regions (&lt;5°). Thus, a large portion of ICESat data over sloping areas has not been used. In this study, we used a new slope correction method to improve the accuracy of estimates of vegetation heights for regions where slopes fall between 5° and 15°. The new method enabled us to use more than 20% additional laser data compared with the existing vegetation height data which only uses ICESat data in relatively flat areas (slope &lt; 5°) in China. With the vegetation height data extracted from ICESat footprints and ancillary data including Moderate Resolution Imaging Spectroradiometer (MODIS) derived data (canopy cover, reflectances and leaf area index), climate data, and topographic data, we developed a wall to wall vegetation height map of China using the Random Forest algorithm. We used the data from 416 field measurements to validate the new vegetation height product. The coefficient of determination (R2) and RMSE of the new vegetation height product were 0.89 and 4.73 m respectively. The accuracy of the product is significantly better than that of the two existing global forest height products produced by Lefsky (2010) and Simard et al. (2011), when compared with the data from 227 field measurements in our study area. The new vegetation height data demonstrated clear distinctions among forest, shrub and grassland, which is promising for improving the classification of vegetation and above-ground forest biomass assessment in China. © 2017 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS)"
"24759735100;","A cautionary note on the computation of daily mean temperatures and their trends",2017,"10.1002/joc.4941","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007223612&doi=10.1002%2fjoc.4941&partnerID=40&md5=05d29366b2e80eb307bf0ebda3fefa9e","There are different methodologies to compute daily mean temperatures (DMT), including averaging the 24-hourly temperature values, readings at specific times throughout the day or simply averaging the minimum and maximum daily temperatures. This study provides an intercomparison of some of such methods applied to six meteorological stations in Argentina with continuous hourly measurements for a period of more than 24 years. Results show that differences arising from the various methodologies are largely dependent on the local weather conditions, particularly those related to cloud cover and wind intensity, while the role of air moisture is less important. Furthermore, trends derived from DMT estimates using different methodologies are found to be highly sensitive to the chosen method. In fact, statistically insignificant trends could be significant should other methodologies to calculate DMT had been used. This result could be of importance for diverse scientific areas such as agriculture or climate warming studies. © 2016 Royal Meteorological Society"
"56237086200;9036557400;57190373951;56402112700;56224155200;56503083100;","Detection of tropical overshooting cloud tops using himawari-8 imagery",2017,"10.3390/rs9070685","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022320006&doi=10.3390%2frs9070685&partnerID=40&md5=8abd1b6588842d17c2da0dfab6b4b077","Overshooting convective cloud Top (OT)-accompanied clouds can cause severe weather conditions, such as lightning, strong winds, and heavy rainfall. The distribution and behavior of OTs can affect regional and global climate systems. In this paper, we propose a new approach for OT detection by using machine learning methods with multiple infrared images and their derived features. Himawari-8 satellite images were used as the main input data, and binary detection (OT or nonOT) with class probability was the output of the machine learning models. Three machine learning techniques-random forest (RF), extremely randomized trees (ERT), and logistic regression (LR)-were used to develop OT classification models to distinguish OT from non-OT. The hindcast validation over the Southeast Asia andWest Pacific regions showed that RF performed best, resulting in a mean probabilities of detection (POD) of 77.06% and a mean false alarm ratio (FAR) of 36.13%. Brightness temperature at 11.2 μm (Tb11) and its standard deviation (STD) in a 3 × 3 window size were identified as the most contributing variables for discriminating OT and nonOT classes. The proposed machine learning-based OT detection algorithms produced promising results comparable to or even better than the existing approaches, which are the infrared window (IRW)-texture and water vapor (WV) minus IRW brightness temperature difference (BTD) methods. © 2017 by the authors."
"36644095800;36992744000;","An explanation for the sensitivity of the mean state of the community atmosphere model to horizontal resolution on aquaplanets",2017,"10.1175/JCLI-D-16-0069.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020088698&doi=10.1175%2fJCLI-D-16-0069.1&partnerID=40&md5=550303a712ff0bf1b2fe718d1bacf6db","The sensitivity of the mean state of the Community Atmosphere Model to horizontal resolutions typical of present-day general circulation models is investigated in an aquaplanet configuration. Nonconvergence of the mean state is characterized by a progressive drying of the atmosphere and large reductions in cloud coverage with increasing resolution. Analyses of energy and moisture budgets indicate that these trends are balanced by variations in moisture transport by the resolved circulation, and a reduction in activity of the convection scheme. In contrast, the large-scale precipitation rate increases with resolution, which is approximately balanced by greater advection of dry static energy associated with more active resolved vertical motion in the ascent region of the Hadley cell. An explanation for the sensitivity of the mean state to horizontal resolution is proposed, based on linear Boussinesq theory. The authors hypothesize that an increase in horizontal resolution in the model leads to a reduction in horizontal scale of the diabatic forcing arising from the column physics, facilitating finescale flow and faster resolved convective updrafts within the dynamical core, and steering the coupled system toward a new mean state. This hypothesis attempts to explain the underlying mechanism driving the variations in moisture transport observed in the simulations. © 2017 American Meteorological Society."
"57212270042;56204280200;37031473100;7006686129;35396858200;24477694300;18438062100;57203776263;6602221672;57200055610;6701378450;7403384594;","Top-of-atmosphere radiative forcing affected by brown carbon in the upper troposphere",2017,"10.1038/ngeo2960","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021824772&doi=10.1038%2fngeo2960&partnerID=40&md5=61e02a0874980409cdb26402aa8372e4","Carbonaceous aerosols affect the global radiative balance by absorbing and scattering radiation, which leads to warming or cooling of the atmosphere, respectively. Black carbon is the main light-absorbing component. A portion of the organic aerosol known as brown carbon also absorbs light. The climate sensitivity to absorbing aerosols rapidly increases with altitude, but brown carbon measurements are limited in the upper troposphere. Here we present aircraft observations of vertical aerosol distributions over the continental United States in May and June 2012 to show that light-absorbing brown carbon is prevalent in the troposphere, and absorbs more short-wavelength radiation than black carbon at altitudes between 5 and 12 km. We find that brown carbon is transported to these altitudes by deep convection, and that in-cloud heterogeneous processing may produce brown carbon. Radiative transfer calculations suggest that brown carbon accounts for about 24% of combined black and brown carbon warming effect at the tropopause. Roughly two-thirds of the estimated brown carbon forcing occurs above 5 km, although most brown carbon is found below 5 km. The highest radiative absorption occurred during an event that ingested a wildfire plume. We conclude that high-altitude brown carbon from biomass burning is an unappreciated component of climate forcing."
"56428347900;12753475500;56050004200;55383415800;57218518385;57194505708;26039604700;7402248742;","First assessment of Sentinel-1A data for surface soil moisture estimations using a coupled water cloud model and advanced integral equation model over the Tibetan Plateau",2017,"10.3390/rs9070714","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85022334904&doi=10.3390%2frs9070714&partnerID=40&md5=c275b1d49c9a8d9bae5f606cc5801cf6","The spatiotemporal distribution of soil moisture over the Tibetan Plateau is important for understanding the regional water cycle and climate change. In this paper, the surface soil moisture in the northeastern Tibetan Plateau is estimated from time-series VV-polarized Sentinel-1A observations by coupling the water cloud model (WCM) and the advanced integral equation model (AIEM). The vegetation indicator in the WCM is represented by the leaf area index (LAI), which is smoothed and interpolated from Terra Moderate Resolution Imaging Spectroradiometer (MODIS) LAI eight-day products. The AIEM requires accurate roughness parameters, which are parameterized by the effective roughness parameters. The first halves of the Sentinel-1A observations from October 2014 to May 2016 are adopted for the model calibration. The calibration results show that the backscattering coefficient σ° simulated from the coupled model are consistent with those of the Sentinel-1A with integrated Pearson's correlation coefficients R of 0.80 and 0.92 for the ascending and descending data, respectively. The variability of soil moisture is correctly modeled by the coupled model. Based on the calibrated model, the soil moisture is retrieved using a look-up table method. The results show that the trends of the in situ soil moisture are effectively captured by the retrieved soil moisture with an integrated R of 0.60 and 0.82 for the ascending and descending data, respectively. The integrated bias, mean absolute error, and root mean square error are 0.006, 0.048, and 0.073 m3/m3 for the ascending data, and are 0.012, 0.026, and 0.055 m3/m3 for the descending data, respectively. Discussions of the effective roughness parameters and uncertainties in the LAI demonstrate the importance of accurate parameterizations of the surface roughness parameters and vegetation for the soil moisture retrieval. These results demonstrate the capability and reliability of Sentinel-1A data for estimating the soil moisture over the Tibetan Plateau. It is expected that our results can contribute to developing operational methods for soil moisture retrieval using the Sentinel-1A and Sentinel-1B satellites. © 2017 by the authors."
"56041866500;57194196888;7006197933;55574436900;56041956600;57194181542;8609367800;56668687700;7102192954;","Data acquisition considerations for Terrestrial Laser Scanning of forest plots",2017,"10.1016/j.rse.2017.04.030","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019151212&doi=10.1016%2fj.rse.2017.04.030&partnerID=40&md5=2d8bbeee02486bbb9c7e07efe9105018","The poor constraint of forest Above Ground Biomass (AGB) is responsible, in part, for large uncertainties in modelling future climate scenarios. Terrestrial Laser Scanning (TLS) can be used to derive unbiased and non-destructive estimates of tree structure and volume and can, therefore, be used to address key uncertainties in forest AGB estimates. Here we review our experience of TLS sampling strategies from 27 campaigns conducted over the past 5 years, across tropical and temperate forest plots, where data was captured with a RIEGL VZ-400 laser scanner. The focus is on strategies to derive Geometrical Modelling metrics (e.g. tree volume) over forest plots (≥1 ha) which require the accurate co-registration of 10s to 100s of individual point clouds. We recommend a 10 m  × 10 m sampling grid as an approach to produce a point cloud with a uniform point distribution, that can resolve higher order branches (down to a few cm in diameter) towards the top of 30+ m canopies and can be captured in a timely fashion i.e. ∼3–6 days per ha. A data acquisition protocol, such as presented here, would facilitate data interoperability and inter-comparison of metrics between instruments/groups, from plot to plot and over time. © 2017 The Authors"
"55373004600;57208346904;","Effects of cumulus parameterization closures on simulations of summer precipitation over the continental United States",2017,"10.1007/s00382-016-3338-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84986300425&doi=10.1007%2fs00382-016-3338-6&partnerID=40&md5=4f8b534d988ba89da8f26cb14b29f7ff","This study examines the effects of five cumulus closure assumptions on simulations of summer precipitation in the continental U.S. by utilizing an ensemble cumulus parameterization (ECP) that incorporates multiple alternate closure schemes into a single cloud model formulation. Results demonstrate that closure algorithms significantly affect the summer mean, daily frequency and intensity, and diurnal variation of precipitation, with strong regional dependence. Overall, the vertical velocity (W) closure produces the smallest summer mean biases, while the moisture convergence (MC) closure most realistically reproduces daily variability. Both closures have advantages over others in simulating U.S. daily rainfall frequency distribution, though both slightly overestimate intense rain events. The MC closure is superior at capturing summer rainfall amount, daily variability, and heavy rainfall frequency over the Central U.S., but systematically produces wet biases over the North American Monsoon (NAM) region and Southeast U.S., which can be reduced by using the W closure. The instability tendency (TD) and the total instability adjustment (KF) closures are better at capturing observed diurnal signals over the Central U.S. and the NAM, respectively. The results reasonably explain the systematic behaviors of several major cumulus parameterizations. A preliminary experiment combining two optimal closures (averaged moisture convergence and vertical velocity) in the ECP scheme significantly reduced the wet (dry) biases over the Southeast U.S. in the summer of 1993 (2003), and greatly improved daily rainfall correlations over the NAM. Further improved model simulation skills may be achieved in the future if optimal closures and their appropriate weights can be derived at different time scales based on specific climate regimes. © 2016, Springer-Verlag Berlin Heidelberg."
"14032501300;7004208584;57037521500;56452368900;56452644200;56486548700;9746433100;56898191700;8553314500;57199220321;7101963685;6701726317;57197840312;6506365150;","Monitoring land surface albedo and vegetation dynamics using high spatial and temporal resolution synthetic time series from Landsat and the MODIS BRDF/NBAR/albedo product",2017,"10.1016/j.jag.2017.03.008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028694954&doi=10.1016%2fj.jag.2017.03.008&partnerID=40&md5=0934dfdbff565b1b513274f7aa855d1d","Seasonal vegetation phenology can significantly alter surface albedo which in turn affects the global energy balance and the albedo warming/cooling feedbacks that impact climate change. To monitor and quantify the surface dynamics of heterogeneous landscapes, high temporal and spatial resolution synthetic time series of albedo and the enhanced vegetation index (EVI) were generated from the 500 m Moderate Resolution Imaging Spectroradiometer (MODIS) operational Collection V006 daily BRDF/NBAR/albedo products and 30 m Landsat 5 albedo and near-nadir reflectance data through the use of the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM). The traditional Landsat Albedo (Shuai et al., 2011) makes use of the MODIS BRDF/Albedo products (MCD43) by assigning appropriate BRDFs from coincident MODIS products to each Landsat image to generate a 30 m Landsat albedo product for that acquisition date. The available cloud free Landsat 5 albedos (due to clouds, generated every 16 days at best) were used in conjunction with the daily MODIS albedos to determine the appropriate 30 m albedos for the intervening daily time steps in this study. These enhanced daily 30 m spatial resolution synthetic time series were then used to track albedo and vegetation phenology dynamics over three Ameriflux tower sites (Harvard Forest in 2007, Santa Rita in 2011 and Walker Branch in 2005). These Ameriflux sites were chosen as they are all quite nearby new towers coming on line for the National Ecological Observatory Network (NEON), and thus represent locations which will be served by spatially paired albedo measures in the near future. The availability of data from the NEON towers will greatly expand the sources of tower albedometer data available for evaluation of satellite products. At these three Ameriflux tower sites the synthetic time series of broadband shortwave albedos were evaluated using the tower albedo measurements with a Root Mean Square Error (RMSE) less than 0.013 and a bias within the range of ±0.006. These synthetic time series provide much greater spatial detail than the 500 m gridded MODIS data, especially over more heterogeneous surfaces, which improves the efforts to characterize and monitor the spatial variation across species and communities. The mean of the difference between maximum and minimum synthetic time series of albedo within the MODIS pixels over a subset of satellite data of Harvard Forest (16 km by 14 km) was as high as 0.2 during the snow-covered period and reduced to around 0.1 during the snow-free period. Similarly, we have used STARFM to also couple MODIS Nadir BRDF Adjusted Reflectances (NBAR) values with Landsat 5 reflectances to generate daily synthetic times series of NBAR and thus Enhanced Vegetation Index (NBAR-EVI) at a 30 m resolution. While normally STARFM is used with directional reflectances, the use of the view angle corrected daily MODIS NBAR values will provide more consistent time series. These synthetic times series of EVI are shown to capture seasonal vegetation dynamics with finer spatial and temporal details, especially over heterogeneous land surfaces. © 2017 The Authors"
"57194682576;22635999400;57126848900;8627503500;56767841200;35547214900;","Remote sensing of multiple cloud layer heights using multi-Angular measurements",2017,"10.5194/amt-10-2361-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021656571&doi=10.5194%2famt-10-2361-2017&partnerID=40&md5=7aa9d18f812b8a692b3b8b34a7afaac8","Cloud top height (CTH) affects the radiative properties of clouds. Improved CTH observations will allow for improved parameterizations in large-scale models and accurate information on CTH is also important when studying variations in freezing point and cloud microphysics. NASA's airborne Research Scanning Polarimeter (RSP) is able to measure cloud top height using a novel multi-Angular contrast approach. For the determination of CTH, a set of consecutive nadir reflectances is selected and the cross correlations between this set and collocated sets at other viewing angles are calculated for a range of assumed cloud top heights, yielding a correlation profile. Under the assumption that cloud reflectances are isotropic, local peaks in the correlation profile indicate cloud layers. This technique can be applied to every RSP footprint and we demonstrate that detection of multiple peaks in the correlation profile allows retrieval of heights of multiple cloud layers within single RSP footprints. This paper provides an in-depth description of the architecture and performance of the RSP's CTH retrieval technique using data obtained during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign. RSP-retrieved cloud heights are evaluated using collocated data from the Cloud Physics Lidar (CPL). The method's accuracy associated with the magnitude of correlation, optical thickness, cloud thickness and cloud height are explored. The technique is applied to measurements at a wavelength of 670 and 1880 nm and their combination. The 1880 nm band is virtually insensitive to the lower troposphere due to strong water vapor absorption. It is found that each band is well suitable for retrieving heights of cloud layers with optical thicknesses above about 0.1 and that RSP cloud layer height retrievals more accurately correspond to CPL cloud middle than cloud top. It is also found that the 1880 nm band yields the most accurate results for clouds at middle and high altitudes (4.0 to 17 km), while the 670 nm band is most accurate at low and middle altitudes (1.0-13.0 km). The dual band performs best over the broadest range and is suitable for accurately retrieving cloud layer heights between 1.0 and 16.0 km. Generally, the accuracy of the retrieved cloud top heights increases with increasing correlation value. Improved accuracy is achieved by using customized filtering techniques for each band with the most significant improvements occurring in the primary layer retrievals. RSP is able to measure a primary layer CTH with a median error of about 0.5 km when compared to CPL. For multilayered scenes, the second and third layer heights are determined median errors of about 1.5 and 2.0-2.5 km, respectively. © Author(s) 2017."
"42761459200;55624488227;36538539800;7404592426;57214419797;7202010686;","Multi-year downscaling application of two-way coupled WRF v3.4 and CMAQ v5.0.2 over east Asia for regional climate and air quality modeling: Model evaluation and aerosol direct effects",2017,"10.5194/gmd-10-2447-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021662859&doi=10.5194%2fgmd-10-2447-2017&partnerID=40&md5=1b3304109a8959758137057b2610c3e8","In this study, a regional coupled climate- chemistry modeling system using the dynamical downscaling technique was established by linking the global Community Earth System Model (CESM) and the regional twoway coupled Weather Research and Forecasting - Community Multi-scale Air Quality (WRF-CMAQ) model for the purpose of comprehensive assessments of regional climate change and air quality and their interactions within one modeling framework. The modeling system was applied over east Asia for a multi-year climatological application during 2006-2010, driven with CESM downscaling data under Representative Concentration Pathways 4.5 (RCP4.5), along with a short-Term air quality application in representative months in 2013 that was driven with a reanalysis dataset. A comprehensive model evaluation was conducted against observations from surface networks and satellite observations to assess the model's performance. This study presents the first application and evaluation of the two-way coupled WRF-CMAQ model for climatological simulations using the dynamical downscaling technique. The model was able to satisfactorily predict major meteorological variables. The improved statistical performance for the 2m temperature (T2) in this study (with a mean bias of 0.6 sC) compared with the Coupled Model Intercomparison Project Phase 5 (CMIP5) multi-models might be related to the use of the regional model WRF and the bias-correction technique applied for CESM downscaling. The model showed good ability to predict PM2:5 in winter (with a normalized mean bias (NMB) of 6.4%in 2013) and O3 in summer (with an NMB of 18.2% in 2013) in terms of statistical performance and spatial distributions. Compared with global models that tend to underpredict PM2:5 concentrations in China, WRF-CMAQ was able to capture the high PM2:5 concentrations in urban areas. In general, the two-way coupled WRF-CMAQ model performed well for both climatological and air quality applications. The coupled modeling system with direct aerosol feedbacks predicted aerosol optical depth relatively well and significantly reduced the overprediction in downward shortwave radiation at the surface (SWDOWN) over polluted regions in China. The performance of cloud variables was not as good as other meteorological variables, and underpredictions of cloud fraction resulted in overpredictions of SWDOWN and underpredictions of shortwave and longwave cloud forcing. The importance of climate-chemistry interactions was demonstrated via the impacts of aerosol direct effects on climate and air quality. The aerosol effects on climate and air quality in east Asia (e.g., SWDOWN and T2 decreased by 21.8Wm2 and 0.45C, respectively, and most pollutant concentrations increased by 4.8-9.5% in January over China's major cities) were more significant than in other regions because of higher aerosol loadings that resulted from severe regional pollution, which indicates the need for applying online-coupled models over east Asia for regional climate and air quality modeling and to study the important climate-chemistry interactions. This work established a baseline for WRF-CMAQ simulations for a future period under the RCP4.5 climate scenario, which will be presented in a future paper. © Author(s) 2017."
"56149492300;55462884000;56942554300;36538539800;6701378450;","Modeling regional air quality and climate: Improving organic aerosol and aerosol activation processes in WRF/Chem version 3.7.1",2017,"10.5194/gmd-10-2333-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021328262&doi=10.5194%2fgmd-10-2333-2017&partnerID=40&md5=216e35fd92447b0a37399722a1187f19","Air quality and climate influence each other through the uncertain processes of aerosol formation and cloud droplet activation. In this study, both processes are improved in the Weather, Research and Forecasting model with Chemistry (WRF/Chem) version 3.7.1. The existing Volatility Basis Set (VBS) treatments for organic aerosol (OA) formation in WRF/Chem are improved by considering the following: the secondary OA (SOA) formation from semi-volatile primary organic aerosol (POA), a semi-empirical formulation for the enthalpy of vaporization of SOA, and functionalization and fragmentation reactions for multiple generations of products from the oxidation of VOCs. Over the continental US, 2-month-long simulations (May to June 2010) are conducted and results are evaluated against surface and aircraft observations during the Nexus of Air Quality and Climate Change (CalNex) campaign. Among all the configurations considered, the best performance is found for the simulation with the 2005 Carbon Bond mechanism (CB05) and the VBS SOA module with semivolatile POA treatment, 25% fragmentation, and the emissions of semi-volatile and intermediate volatile organic compounds being 3 times the original POA emissions. Among the three gas-phase mechanisms (CB05, CB6, and SAPRC07) used, CB05 gives the best performance for surface ozone and PM2.5 concentrations. Differences in SOA predictions are larger for the simulations with different VBS treatments (e.g., nonvolatile POA versus semivolatile POA) compared to the simulations with different gas-phase mechanisms. Compared to the simulation with CB05 and the default SOA module, the simulations with the VBS treatment improve cloud droplet number concentration (CDNC) predictions (normalized mean biases from -40.8% to a range of -34.6 to -27.7%), with large differences between CB05-CB6 and SAPRC07 due to large differences in their OH and HO2 predictions. An advanced aerosol activation parameterization based on the Fountoukis and Nenes (2005) series reduces the large negative CDNC bias associated with the default Abdul Razzak and Ghan (2000) parameterization from -35.4% to a range of -0.8 to 7.1%. However, it increases the errors due to overpredictions of CDNC, mainly over the northeastern US. This work indicates a need to improve other aerosol-cloud-radiation processes in the model, such as the spatial distribution of aerosol optical depth and cloud condensation nuclei, in order to further improve CDNC predictions. © Author(s) 2017."
"7003961165;55227317300;40661753400;40661020000;56210163300;9233045100;57211094015;57191510259;23567488100;7102432430;","Comparison of hourly surface downwelling solar radiation estimated from MSG-SEVIRI and forecast by the RAMS model with pyranometers over Italy",2017,"10.5194/amt-10-2337-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021323597&doi=10.5194%2famt-10-2337-2017&partnerID=40&md5=a6c5729e57f50cf082b555a1951f535d","In this paper, we evaluate the performance of two global horizontal solar irradiance (GHI) estimates, one derived from Meteosat Second Generation (MSG) and another from the 1-day forecast of the Regional Atmospheric Modeling System (RAMS) mesoscale model. The horizontal resolution of the MSG-GHI is 3 × 5 km2 over Italy, which is the focus area of this study. For this paper, RAMS has the horizontal resolution of 4 km. The performances of the MSG-GHI estimate and RAMS-GHI 1-day forecast are evaluated for 1 year (1 June 2013-31 May 2014) against data of 12 ground-based pyranometers over Italy spanning a range of climatic conditions, i.e. from maritime Mediterranean to Alpine climate. Statistics for hourly GHI and daily integrated GHI are presented for the four seasons and the whole year for all the measurement sites. Different sky conditions are considered in the analysis Results for hourly data show an evident dependence on the sky conditions, with the root mean square error (RMSE) increasing from clear to cloudy conditions. The RMSE is substantially higher for Alpine stations in all the seasons, mainly because of the increase of the cloud coverage for these stations, which is not well represented at the satellite and model resolutions. Considering the yearly statistics computed from hourly data for the RAMS model, the RMSE ranges from 152 W m-2 (31 %) obtained for Cozzo Spadaro, a maritime station, to 287 W m-2 (82 %) for Aosta, an Alpine site. Considering the yearly statistics computed from hourly data for MSG-GHI, the minimum RMSE is for Cozzo Spadaro (71 W m-2, 14 %), while the maximum is for Aosta (181 W m-2, 51 %). The mean bias error (MBE) shows the tendency of RAMS to over-forecast the GHI, while no specific behaviour is found for MSG-GHI. Results for daily integrated GHI show a lower RMSE compared to hourly GHI evaluation for both RAMS-GHI 1-day forecast and MSG-GHI estimate. Considering the yearly evaluation, the RMSE of daily integrated GHI is at least 9 % lower (in percentage units, from 31 to 22 % for RAMS in Cozzo Spadaro) than the RMSE computed for hourly data for each station. A partial compensation of underestimation and overestimation of the GHI contributes to the RMSE reduction. Furthermore, a post-processing technique, namely model output statistics (MOS), is applied to improve the GHI forecast at hourly and daily temporal scales. The application of MOS shows an improvement of RAMS-GHI forecast, which depends on the site considered, while the impact of MOS on MSG-GHI RMSE is small. © Author(s) 2017."
"24757696000;6602600408;7004020627;57194586250;26632168400;55326237100;35611334800;56060986400;56250185400;","Implementation of aerosol-cloud interactions in the regional atmosphere-aerosol model COSMO-Muscat(5.0) and evaluation using satellite data",2017,"10.5194/gmd-10-2231-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021101500&doi=10.5194%2fgmd-10-2231-2017&partnerID=40&md5=18a77e2265e0942f40347709d3e61bad","The regional atmospheric model Consortium for Small-scale Modeling (COSMO) coupled to the Multi-Scale Chemistry Aerosol Transport model (Muscat) is extended in this work to represent aerosol-cloud interactions. Previously, only one-way interactions (scavenging of aerosol and in-cloud chemistry) and aerosol-radiation interactions were included in this model. The new version allows for a microphysical aerosol effect on clouds. For this, we use the optional two-moment cloud microphysical scheme in COSMO and the online-computed aerosol information for cloud condensation nuclei concentrations (Cccn), replacing the constant Cccn profile. In the radiation scheme, we have implemented a droplet-size-dependent cloud optical depth, allowing now for aerosol-cloud-radiation interactions. To evaluate the models with satellite data, the Cloud Feedback Model Intercomparison Project Observation Simulator Package (COSP) has been implemented. A case study has been carried out to understand the effects of the modifications, where the modified modeling system is applied over the European domain with a horizontal resolution of 0.25°g × g0.25°. To reduce the complexity in aerosol-cloud interactions, only warm-phase clouds are considered. We found that the online-coupled aerosol introduces significant changes for some cloud microphysical properties. The cloud effective radius shows an increase of 9.5g%, and the cloud droplet number concentration is reduced by 21.5g%."
"36822103700;57203102974;7102944401;14035836100;24074763000;57209647985;7006107059;","Aerosol indirect effects on the nighttime Arctic Ocean surface from thin, predominantly liquid clouds",2017,"10.5194/acp-17-7311-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021167690&doi=10.5194%2facp-17-7311-2017&partnerID=40&md5=7404747bd572d670a09ba41162148e47","Aerosol indirect effects have potentially large impacts on the Arctic Ocean surface energy budget, but model estimates of regional-scale aerosol indirect effects are highly uncertain and poorly validated by observations. Here we demonstrate a new way to quantitatively estimate aerosol indirect effects on a regional scale from remote sensing observations. In this study, we focus on nighttime, optically thin, predominantly liquid clouds. The method is based on differences in cloud physical and microphysical characteristics in carefully selected clean, average, and aerosol-impacted conditions. The cloud subset of focus covers just g1/4 5g% of cloudy Arctic Ocean regions, warming the Arctic Ocean surface by g1/4g1-1.4gWgmg2 regionally during polar night. However, within this cloud subset, aerosol and cloud conditions can be determined with high confidence using CALIPSO and CloudSat data and model output. This cloud subset is generally susceptible to aerosols, with a polar nighttime estimated maximum regionally integrated indirect cooling effect of g1/4 g0.11gWgmg2 at the Arctic sea ice surface (g1/4g8g% of the clean background cloud effect), excluding cloud fraction changes. Aerosol presence is related to reduced precipitation, cloud thickness, and radar reflectivity, and in some cases, an increased likelihood of cloud presence in the liquid phase. These observations are inconsistent with a glaciation indirect effect and are consistent with either a deactivation effect or less-efficient secondary ice formation related to smaller liquid cloud droplets. However, this cloud subset shows large differences in surface and meteorological forcing in shallow and higher-altitude clouds and between sea ice and open-ocean regions. For example, optically thin, predominantly liquid clouds are much more likely to overlay another cloud over the open ocean, which may reduce aerosol indirect effects on the surface. Also, shallow clouds over open ocean do not appear to respond to aerosols as strongly as clouds over stratified sea ice environments, indicating a larger influence of meteorological forcing over aerosol microphysics in these types of clouds over the rapidly changing Arctic Ocean."
"55838659500;6603422104;16202694600;7004060399;","CMIP5 models' shortwave cloud radiative response and climate sensitivity linked to the climatological Hadley cell extent",2017,"10.1002/2017GL073151","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020730383&doi=10.1002%2f2017GL073151&partnerID=40&md5=47b2530b75912b5152b009d7e433abb4","This study analyzes Coupled Model Intercomparison Project phase 5 (CMIP5) model output to examine the covariability of interannual Southern Hemisphere Hadley cell (HC) edge latitude shifts and shortwave cloud radiative effect (SWCRE). In control climate runs, during years when the HC edge is anomalously poleward, most models substantially reduce the shortwave radiation reflected by clouds in the lower midlatitude region (LML; ∼28°S–∼48°S), although no such reduction is seen in observations. These biases in HC-SWCRE covariability are linked to biases in the climatological HC extent. Notably, models with excessively equatorward climatological HC extents have weaker climatological LML subsidence and exhibit larger increases in LML subsidence with poleward HC edge expansion. This behavior, based on control climate interannual variability, has important implications for the CO2-forced model response. In 4×CO2-forced runs, models with excessively equatorward climatological HC extents produce stronger SW cloud radiative warming in the LML region and tend to have larger climate sensitivity values than models with more realistic climatological HC extents. ©2017. American Geophysical Union. All Rights Reserved."
"57194570429;7202571007;7101689290;","Analyzing cloud base at local and regional scales to understand tropical montane cloud forest vulnerability to climate change",2017,"10.5194/acp-17-7245-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020897714&doi=10.5194%2facp-17-7245-2017&partnerID=40&md5=662f302c3e2594bdba8f9b60cdb70884","The degree to which cloud immersion provides water in addition to rainfall, suppresses transpiration, and sustains tropical montane cloud forests (TMCFs) during rainless periods is not well understood. Climate and land use changes represent a threat to these forests if cloud base altitude rises as a result of regional warming or deforestation. To establish a baseline for quantifying future changes in cloud base, we installed a ceilometer at 100ĝ€m altitude in the forest upwind of the TMCF that occupies an altitude range from ĝ1/4 600ĝ€m to the peaks at 1100ĝ€m in the Luquillo Mountains of eastern Puerto Rico. Airport Automated Surface Observing System (ASOS) ceilometer data, radiosonde data, and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite data were obtained to investigate seasonal cloud base dynamics, altitude of the trade-wind inversion (TWI), and typical cloud thickness for the surrounding Caribbean region. Cloud base is rarely quantified near mountains, so these results represent a first look at seasonal and diurnal cloud base dynamics for the TMCF. From May 2013 to August 2016, cloud base was lowest during the midsummer dry season, and cloud bases were lower than the mountaintops as often in the winter dry season as in the wet seasons. The lowest cloud bases most frequently occurred at higher elevation than 600ĝ€m, from 740 to 964ĝ€m. The Luquillo forest low cloud base altitudes were higher than six other sites in the Caribbean by ĝ1/4 200-600ĝ€m, highlighting the importance of site selection to measure topographic influence on cloud height. Proximity to the oceanic cloud system where shallow cumulus clouds are seasonally invariant in altitude and cover, along with local trade-wind orographic lifting and cloud formation, may explain the dry season low clouds. The results indicate that climate change threats to low-elevation TMCFs are not limited to the dry season; changes in synoptic-scale weather patterns that increase frequency of drought periods during the wet seasons (periods of higher cloud base) may also impact ecosystem health. © Author(s) 2017."
"55241800100;13403622000;","Testing the sensitivity of past climates to the indirect effects of dust",2017,"10.1002/2017GL072584","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020462950&doi=10.1002%2f2017GL072584&partnerID=40&md5=cd6b52540df13888ac49eddb6693ad6f","Mineral dust particles are important ice nuclei (IN) and as such indirectly impact Earth's radiative balance via the properties of cold clouds. Using the Community Earth System Model version 1.0.6, and Community Atmosphere Model version 5.1, and a new empirical parameterization for ice nucleation on dust particles, we investigate the radiative forcing induced by dust IN for different dust loadings. Dust emissions are representative of global conditions for the Last Glacial Maximum and the mid-Pliocene Warm Period. Increased dust leads to smaller and more numerous ice crystals in mixed phase clouds, impacting cloud opacity, lifetime, and precipitation. This increases the shortwave cloud radiative forcing, resulting in significant surface temperature cooling and polar amplification—which is underestimated in existing studies relative to paleoclimate archives. Large hydrological changes occur and are linked to an enhanced dynamical response. We conclude that dust indirect effects could potentially have a significant impact on the model-data mismatch that exists for paleoclimates. ©2017. American Geophysical Union. All Rights Reserved."
"55614754800;35932420900;57194565381;54383910700;56506973700;6701557528;7201504886;","Evaluation of large-eddy simulations forced with mesoscale model output for a multi-week period during a measurement campaign",2017,"10.5194/acp-17-7083-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020864742&doi=10.5194%2facp-17-7083-2017&partnerID=40&md5=a488b62f32658d2fa19856300d76f99a","Large-eddy simulations (LESs) of a multi-week period during the HD(CP)2 (High-Definition Clouds and Precipitation for advancing Climate Prediction) Observational Prototype Experiment (HOPE) conducted in Germany are evaluated with respect to mean boundary layer quantities and turbulence statistics. Two LES models are used in a semi-idealized setup through forcing with mesoscale model output to account for the synoptic-scale conditions. Evaluation is performed based on the HOPE observations. The mean boundary layer characteristics like the boundary layer depth are in a principal agreement with observations. Simulating shallow-cumulus layers in agreement with the measurements poses a challenge for both LES models. Variance profiles agree satisfactorily with lidar measurements. The results depend on how the forcing data stemming from mesoscale model output are constructed. The mean boundary layer characteristics become less sensitive if the averaging domain for the forcing is large enough to filter out mesoscale fluctuations. © Author(s) 2017."
"26653800000;57208121852;55417497600;55749785900;56597778200;","Evaluating the diurnal cycle in cloud top temperature from SEVIRI",2017,"10.5194/acp-17-7035-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020886338&doi=10.5194%2facp-17-7035-2017&partnerID=40&md5=cbd512ede28768ec60cab70bf3433866","The variability of convective cloud spans a wide range of temporal and spatial scales and is of fundamental importance for global weather and climate systems. Datasets from geostationary satellite instruments such as the Spinning Enhanced Visible and Infrared Imager (SEVIRI) provide high-time-resolution observations across a large area. In this study we use data from SEVIRI to quantify the diurnal cycle of cloud top temperature within the instrument's field of view and discuss these results in relation to retrieval biases. We evaluate SEVIRI cloud top temperatures from the new CLAAS-2 (CLoud property dAtAset using SEVIRI, Edition 2) dataset against Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data. Results show a mean bias of +0.44 K with a standard deviation of 11.7 K, which is in agreement with previous validation studies. Analysis of the spatio-temporal distribution of these errors shows that absolute retrieval biases vary from less than 5 K over the southeast Atlantic Ocean up to 30 K over central Africa at night. Night- and daytime retrieval biases can also differ by up to 30 K in some areas, potentially contributing to biases in the estimated amplitude of the diurnal cycle. This illustrates the importance of considering spatial and diurnal variations in retrieval errors when using the CLAAS-2 dataset. Keeping these biases in mind, we quantify the seasonal, diurnal, and spatial variation of cloud top temperature across SEVIRI's field of view using the CLAAS-2 dataset. By comparing the mean diurnal cycle of cloud top temperature with the retrieval bias, we find that diurnal variations in the retrieval bias can be small but are often of the same order of magnitude as the amplitude of the observed diurnal cycle, indicating that in some regions the diurnal cycle apparent in the observations may be significantly impacted by diurnal variability in the accuracy of the retrieval. We show that the CLAAS-2 dataset can measure the diurnal cycle of cloud tops accurately in regions of stratiform cloud such as the southeast Atlantic Ocean and Europe, where cloud top temperature retrieval biases are small and exhibit limited spatial and temporal variability. Quantifying the diurnal cycle over the tropics and regions of desert is more difficult, as retrieval biases are larger and display significant diurnal variability. CLAAS-2 cloud top temperature data are found to be of limited skill in measuring the diurnal cycle accurately over desert regions. In tropical regions such as central Africa, the diurnal cycle can be described by the CLAAS-2 data to some extent, although retrieval biases appear to reduce the amplitude of the real diurnal cycle of cloud top temperatures. This is the first study to relate the diurnal variations in SEVIRI retrieval bias to observed diurnal cycles in cloud top temperature. Our results may be of interest to those in the observation and modelling communities when using cloud top properties data from SEVIRI, particularly for studies considering the diurnal cycle of convection. © Author(s) 2017."
"57194491444;7005304841;56153039700;24472110700;7003875148;24398842400;","Modelling micro- and macrophysical contributors to the dissipation of an Arctic mixed-phase cloud during the Arctic Summer Cloud Ocean Study (ASCOS)",2017,"10.5194/acp-17-6693-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020479765&doi=10.5194%2facp-17-6693-2017&partnerID=40&md5=add328872f0a040f4336dd470be21c2b","The Arctic climate is changing; temperature changes in the Arctic are greater than at midlatitudes, and changing atmospheric conditions influence Arctic mixed-phase clouds, which are important for the Arctic surface energy budget. These low-level clouds are frequently observed across the Arctic. They impact the turbulent and radiative heating of the open water, snow, and sea-ice-covered surfaces and influence the boundary layer structure. Therefore the processes that affect mixed-phase cloud life cycles are extremely important, yet relatively poorly understood. In this study, we present sensitivity studies using semi-idealized large eddy simulations (LESs) to identify processes contributing to the dissipation of Arctic mixed-phase clouds. We found that one potential main contributor to the dissipation of an observed Arctic mixed-phase cloud, during the Arctic Summer Cloud Ocean Study (ASCOS) field campaign, was a low cloud droplet number concentration (CDNC) of about 2ĝ€ cmĝ '3. Introducing a high ice crystal concentration of 10ĝ€ Lĝ '1 also resulted in cloud dissipation, but such high ice crystal concentrations were deemed unlikely for the present case. Sensitivity studies simulating the advection of dry air above the boundary layer inversion, as well as a modest increase in ice crystal concentration of 1ĝ€ Lĝ'1, did not lead to cloud dissipation. As a requirement for small droplet numbers, pristine aerosol conditions in the Arctic environment are therefore considered an important factor determining the lifetime of Arctic mixed-phase clouds. © Author(s) 2017."
"6603051005;56401135900;16444841300;54962189200;57201515900;55311990500;7003838015;57000038900;56400951100;7201563100;45260923100;7005189183;24331412400;9333422400;7201961277;35117831300;6602675912;15071249200;45261395400;8262277400;6701547852;57194495626;57194504310;56270700700;","The MUMBA campaign: Measurements of urban, marine and biogenic air",2017,"10.5194/essd-9-349-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020429429&doi=10.5194%2fessd-9-349-2017&partnerID=40&md5=e1e41acb9659d1e086414dfb0b4ae5cf","The Measurements of Urban, Marine and Biogenic Air (MUMBA) campaign took place in Wollongong, New South Wales (a small coastal city approximately 80ĝ€km south of Sydney, Australia) from 21 December 2012 to 15 February 2013. Like many Australian cities, Wollongong is surrounded by dense eucalyptus forest, so the urban airshed is heavily influenced by biogenic emissions. Instruments were deployed during MUMBA to measure the gaseous and aerosol composition of the atmosphere with the aim of providing a detailed characterisation of the complex environment of the ocean-forest-urban interface that could be used to test the skill of atmospheric models. The gases measured included ozone, oxides of nitrogen, carbon monoxide, carbon dioxide, methane and many of the most abundant volatile organic compounds. The aerosol characterisation included total particle counts above 3ĝ€nm, total cloud condensation nuclei counts, mass concentration, number concentration size distribution, aerosol chemical analyses and elemental analysis.<br><br>The campaign captured varied meteorological conditions, including two extreme heat events, providing a potentially valuable test for models of future air quality in a warmer climate. There was also an episode when the site sampled clean marine air for many hours, providing a useful additional measure of the background concentrations of these trace gases within this poorly sampled region of the globe. In this paper we describe the campaign, the meteorology and the resulting observations of atmospheric composition in general terms in order to equip the reader with a sufficient understanding of the Wollongong regional influences to use the MUMBA datasets as a case study for testing a chemical transport model. The data are available from PANGAEA (<a hrefCombining double low line""http://doi.pangaea.de/10.1594/PANGAEA.871982"" targetCombining double low line""-blank"">http://doi.pangaea.de/10.1594/PANGAEA.871982</a>). © Author(s) 2017."
"12801992200;57198208348;24722339600;7006307463;","Evaluation of hemispheric asymmetries in marine cloud radiative properties",2017,"10.1175/JCLI-D-16-0263.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019070992&doi=10.1175%2fJCLI-D-16-0263.1&partnerID=40&md5=2eb19ea42e2c8deb7f73fbdce2bd444e","The hemispheric symmetry of albedo and its contributing factors in satellite observations and global climate models is evaluated. The analysis is performed on the annual mean time scale, on which a bimodality in the joint distribution of albedo and cloud fraction is evident, resulting from tropical and subtropical clouds and midlatitude clouds, respectively. Hemispheric albedo symmetry is not found in individual ocean-only latitude bands; comparing the Northern and Southern Hemisphere (NH and SH), regional mean albedo is higher in the NH tropics and lower in the NH subtropics and midlatitudes than in the SH counterparts. This follows the hemispheric asymmetry of cloud fraction. In midlatitudes and tropics the hemispheric asymmetry in cloud albedo also contributes to the asymmetry in total albedo, whereas in the subtropics the cloud albedo is more hemispherically symmetric. According to the observations, cloud contributions to compensation for higher clear-sky albedo in the NH come primarily from cloud albedo in midlatitudes and cloud amount in the subtropics. Current-generation climate models diverge in their representation of these relationships, but common features of the model-data comparison include weaker-than-observed asymmetry in cloud fraction and cloud albedo in the tropics, weaker or reversed cloud fraction asymmetry in the subtropics, and agreement with observed cloud albedo asymmetry in the midlatitudes. Models on average reproduce the NH-SH asymmetry in total albedo over the 60°S-60°N ocean but show higher occurrence of brighter clouds in the SH compared to observations. The albedo bias in both hemispheres is reinforced by overestimated clear-sky albedo in the models. © 2017 American Meteorological Society."
"57194504025;7202970886;","A MODIS-derived value-added climatology of maritime cloud liquid water path that conserves solar reflectance",2017,"10.1175/JAMC-D-16-0241.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020379359&doi=10.1175%2fJAMC-D-16-0241.1&partnerID=40&md5=158c9b762cca52d6345bae5893d60d81","A dataset is generated from a method to retrieve distributions of cloud liquid water path over partially cloudy scenes. The method was introduced in a 2011 paper by Foster and coauthors that described the theory and provided test cases. Here it has been applied to Moderate Resolution Imaging Spectroradiometer (MODIS) collection-5 and collection-6 cloud products, resulting in a value-added dataset that contains adjusted distributions of cloud liquid water path for more than 10 years for marine liquid cloud for both Aqua and Terra. This method adjusts horizontal distributions of cloud optical properties to be more consistent with observed visible reflectance and is especially useful in areas where cloud optical retrievals fail or are considered to be of low quality. Potential uses of this dataset include validation of climate and radiative transfer models and facilitation of studies that intercompare satellite records. Results show that the fit method is able to reduce bias between observed visible reflectance and that derived from optical retrievals by up to an average improvement of 3%. The level of improvement is dependent on several factors, including seasonality, viewing geometry, cloud fraction, and cloud heterogeneity. Applications of this dataset are explored through a satellite intercomparison with PATMOS-x and Global Change Observation Mission-First Water (GCOM-W1; ""SHIZUKU"") AMSR-2 and use of a Monte Carlo radiative transfer model. From the 3D Monte Carlo model simulations, albedo biases are found when the method is applied, with seasonal averages that range over 0.02-0.06. © 2017 American Meteorological Society."
"57194201247;7004479957;6701346974;","Cloud and circulation feedbacks in a near-global aquaplanet cloud-resolving model",2017,"10.1002/2016MS000872","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019111827&doi=10.1002%2f2016MS000872&partnerID=40&md5=f56da88225433e8775d2af74657d3a3b","A near-global aquaplanet cloud-resolving model (NGAqua) with fixed meridionally varying sea-surface temperature (SST) is used to investigate cloud feedbacks due to three climate perturbations: a uniform 4 K SST increase, a quadrupled-CO2 concentration, and both combined. NGAqua has a horizontal resolution of 4 km with no cumulus parameterization. Its domain is a zonally periodic 20,480 km-long tropical channel, spanning 46°S–N. It produces plausible mean distributions of clouds, rainfall, and winds. After spin-up, 80 days are analyzed for the control and increased-SST simulations, and 40 days for those with quadrupled CO2. The Intertropical Convergence Zone width and tropical cloud cover are not strongly affected by SST warming or CO2 increase, except for the expected upward shift in high clouds with warming, but both perturbations weaken the Hadley circulation. Increased SST induces a statistically significant increase in subtropical low cloud fraction and in-cloud liquid water content but decreases midlatitude cloud, yielding slightly positive domain-mean shortwave cloud feedbacks. CO2 quadrupling causes a slight shallowing and a statistically insignificant reduction of subtropical low cloud fraction. Warming-induced low cloud changes are strongly correlated with changes in estimated inversion strength, which increases modestly in the subtropics but decreases in the midlatitudes. Enhanced clear-sky boundary layer radiative cooling in the warmer climate accompanies the robust subtropical low cloud increase. The probability distribution of column relative humidity across the tropics and subtropics is compared between the control and increased-SST simulations. It shows no evidence of bimodality or increased convective aggregation in a warmer climate. © 2017. The Authors."
"57193926688;55751665200;6505762249;56708460400;34870277200;7003495982;","Revised cloud processes to improve the mean and intraseasonal variability of Indian summer monsoon in climate forecast system: Part 1",2017,"10.1002/2016MS000819","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018251678&doi=10.1002%2f2016MS000819&partnerID=40&md5=dc2a9798fe7d3060a90c1551bdc1ab95","The National Centre for Environmental Prediction (NCEP) Climate Forecast System (CFS) is being used for operational monsoon prediction over the Indian region. Recent studies indicate that the moist convective process in CFS is one of the major sources of uncertainty in monsoon predictions. In this study, the existing simple cloud microphysics of CFS is replaced by the six-class Weather Research Forecasting (WRF) single moment (WSM6) microphysical scheme. Additionally, a revised convective parameterization is employed to improve the performance of the model in simulating the boreal summer mean climate and intraseasonal variability over the Indian summer monsoon (ISM) region. The revised version of the model (CFSCR) exhibits a potential to improve shortcomings in the seasonal mean precipitation distribution relative to the standard CFS (CTRL), especially over the ISM region. Consistently, notable improvements are also evident in other observed ISM characteristics. These improvements are found to be associated with a better simulation of spatial and vertical distributions of cloud hydrometeors in CFSCR. A reasonable representation of the subgrid-scale convective parameterization along with cloud hydrometeors helps to improve the convective and large-scale precipitation distribution in the model. As a consequence, the simulated low-frequency boreal summer intraseasonal oscillation (BSISO) exhibits realistic propagation and the observed northwest-southeast rainband is well reproduced in CFSCR. Additionally, both the high and low-frequency BSISOs are better captured in CFSCR. The improvement of low and high-frequency BSISOs in CFSCR is shown to be related to a realistic phase relationship of clouds. © 2017. The Authors."
"55717244800;55930003300;36015299300;8906055900;","Impact of detrained cumulus on climate simulated by the Community Atmosphere Model Version 5 with a unified convection scheme",2017,"10.1002/2016MS000877","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020423735&doi=10.1002%2f2016MS000877&partnerID=40&md5=1ec54ab11855fe8db874631b63c48b6b","Cumulus elements generated by detraining convective condensate–detrained cumulus–are added to the Community Atmosphere Model Version 5 (CAM5) combined with a Unified Convection Scheme (UNICON). Instead of evaporating convective liquids detrained into clear portions, we diagnosed a new detrained cumulus that is horizontally nonoverlapped with cumulus and stratus in each layer by assuming a steady state balance between the detrainment rate of cumulus condensates and the dissipation rate of detrained condensates by entrainment mixing with environmental air. The addition of detrained cumulus was found to substantially improve the simulation of low-level clouds and the associated shortwave cloud radiative forcing, particularly in the subtropical trade cumulus regime. In addition to the mean climate, successful simulations of the diurnal cycle of precipitation, Madden-Julian Oscillation, and Kelvin wave were also well maintained. © 2017. The Authors."
"7201472576;57190384098;6701819583;55541379500;9246517900;","Impact of AVHRR Channel 3b noise on climate data records: Filtering method applied to the CM SAF CLARA-A2 data record",2017,"10.3390/rs9060568","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021054667&doi=10.3390%2frs9060568&partnerID=40&md5=4c07f9698c0627bbc0875f666041e01b","A method for reducing the impact of noise in the 3.7 micron spectral channel in climate data records derived from coarse resolution (4 km) global measurements from the Advanced Very High Resolution Radiometer (AVHRR) data is presented. A dynamic size-varying median filter is applied to measurements guided by measured noise levels and scene temperatures for individual AVHRR sensors on historic National Oceanic and Atmospheric Administration (NOAA) polar orbiting satellites in the period 1982-2001. The method was used in the preparation of the CM SAF cLoud, Albedo and surface RAdiation dataset from AVHRR data-Second Edition (CLARA-A2), a cloud climate data record produced by the EUMETSAT Satellite Application Facility for Climate Monitoring (CM SAF), as well as in the preparation of the corresponding AVHRR-based datasets produced by the European Space Agency (ESA) Climate Change Initiative (CCI) project ESA-CLOUD-CCI. The impact of the noise filter was equivalent to removing an artificial decreasing trend in global cloud cover of 1-2% per decade in the studied period, mainly explained by the very high noise levels experienced in data from the first satellites in the series (NOAA-7 and NOAA-9). © 2017 by the authors."
"57194405950;6701606453;57190852346;","Observational evidence linking arctic supercooled liquid cloud biases in CESM to snowfall processes",2017,"10.1175/JCLI-D-16-0666.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017938948&doi=10.1175%2fJCLI-D-16-0666.1&partnerID=40&md5=20fdc0e27d5f9d4823daaf5864867bc9","Clouds are a key regulator of Earth's surface energy balance. The presence or absence of clouds, along with their macroscale and microscale characteristics, is the primary factor modulating the amount of radiation incident on the surface. Recent observational studies in the Arctic highlight the ubiquity of supercooled liquid-containing clouds (LCCs) and their disproportionately large impact on surface melt. Global climate models (GCMs) do not simulate enough Arctic LCCs compared to observations, and thus fail to represent the surface energy balance correctly. This work utilizes spaceborne observations from NASA's A-Train satellite constellation to explore physical processes behind LCCs and surface energy biases in the Community Earth System Model Large Ensemble (CESM-LE) project output. On average CESM-LE underestimates LCC frequency by ~18% over the Arctic, resulting in a ~20 W m-2 bias in downwelling longwave radiation (DLR) over the ~18 × 106 km2 area examined. Collocated observations of falling snow and LCCs indicate that Arctic LCCs produce precipitation ~13% of the time. Conversely, CESM-LE generates snow in ~70% of LCCs. This result indicates that the Wegener-Bergeron-Findeisen (WBF) process-the growth of ice at the expense of supercooled liquid-may be too strong in the model, causing ice to scavenge polar supercooled cloud liquid too efficiently. Ground-based observations from Summit Station, Greenland, provide further evidence of these biases on a more local scale, suggesting that CESM-LE overestimates snow frequency in LCCs by ~52% at the center of the ice sheet leading to ~21% too few LCCs and ~24 W m-2 too little DLR. © 2017 American Meteorological Society."
"55399935700;7006248174;","Which way will the circulation shift in a changing climate? Possible nonlinearity of extratropical cloud feedbacks",2017,"10.1007/s00382-016-3301-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982957461&doi=10.1007%2fs00382-016-3301-6&partnerID=40&md5=58cecc3135163c36176f979c87bedbec","In a suite of idealized experiments with the Community Atmospheric Model version 3 coupled to a slab ocean, we show that the atmospheric circulation response to CO2 increase is sensitive to extratropical cloud feedback that is potentially nonlinear. Doubling CO2 produces a poleward shift of the Southern Hemisphere (SH) midlatitude jet that is driven primarily by cloud shortwave feedback and modulated by ice albedo feedback, in agreement with earlier studies. More surprisingly, for CO2 increases smaller than ~25 %, the SH jet shifts equatorward. Nonlinearities are also apparent in the Northern Hemisphere, but with less zonal symmetry. Baroclinic instability theory and climate feedback analysis suggest that as the CO2 forcing amplitude is reduced, there is a transition from a regime in which cloud and circulation changes are largely decoupled to a regime in which they are highly coupled. In the dynamically coupled regime, there is an apparent cancellation between cloud feedback due to warming and cloud feedback due to the shifting jet, and this allows the ice albedo feedback to dominate in the high latitudes. The extent to which dynamical coupling effects exceed thermodynamic forcing effects is strongly influenced by cloud microphysics: an alternate model configuration with slightly increased cloud liquid (LIQ) produces poleward jet shifts regardless of the amplitude of CO2 forcing. Altering the cloud microphysics also produces substantial spread in the circulation response to CO2 doubling: the LIQ configuration produces a poleward SH jet shift approximately twice that produced under the default configuration. Analysis of large ensembles of the Canadian Earth System Model version 2 demonstrates that nonlinear, cloud-coupled jet shifts are also possible in comprehensive models. We still expect a poleward trend in SH jet latitude for timescales on which CO2 increases by more than ~25 %. But on shorter timescales, our results give good reason to expect significant equatorward deviations. We also discuss the implications for understanding the circulation response to small external forcings from other sources, such as the solar cycle. © 2016, Springer-Verlag Berlin Heidelberg."
"24168416900;7103016965;","The role of ice microphysics parametrizations in determining the prevalence of supercooled liquid water in high-resolution simulations of a Southern Ocean midlatitude cyclone",2017,"10.1175/JAS-D-16-0165.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020239581&doi=10.1175%2fJAS-D-16-0165.1&partnerID=40&md5=6f545b3680dbf2044b1ecf40cb5a86d7","High-resolution simulations of a Southern Ocean cyclone are compared to satellite-derived observations of liquid water path, cloud-top properties, and top-of-atmosphere radiative fluxes. The focus is on the cold-air-outflow region, where there are contributions to the hydrological budget from the microphysical growth of ice particles by riming and vapor deposition and transport by turbulent mixing. The sensitivity of the simulation to the parameterization of these processes is tested and the relative importance of ice-nucleation temperature is identified. It is shown that ice-phase microphysics is a key factor determining the phase composition of Southern Ocean clouds and physically reasonable parameterization changes are identified that affect the liquid water content of these clouds. The information gained from the sensitivity tests is applied to global model development, where it is shown that a modification to the riming parameterization improves climate mean-state biases in the Southern Ocean region. © 2017 American Meteorological Society."
"55351266200;23668563600;7401836526;26644916900;56909327200;","Numerics and subgrid-scale modeling in large eddy simulations of stratocumulus clouds",2017,"10.1002/2016MS000778","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026642909&doi=10.1002%2f2016MS000778&partnerID=40&md5=14ec5e79db123e1eefa9fbee478293ac","Stratocumulus clouds are the most common type of boundary layer cloud; their radiative effects strongly modulate climate. Large eddy simulations (LES) of stratocumulus clouds often struggle to maintain fidelity to observations because of the sharp gradients occurring at the entrainment interfacial layer at the cloud top. The challenge posed to LES by stratocumulus clouds is evident in the wide range of solutions found in the LES intercomparison based on the DYCOMS-II field campaign, where simulated liquid water paths for identical initial and boundary conditions varied by a factor of nearly 12. Here we revisit the DYCOMS-II RF01 case and show that the wide range of previous LES results can be realized in a single LES code by varying only the numerical treatment of the equations of motion and the nature of subgrid-scale (SGS) closures. The simulations that maintain the greatest fidelity to DYCOMS-II observations are identified. The results show that using weighted essentially non-oscillatory (WENO) numerics for all resolved advective terms and no explicit SGS closure consistently produces the highest-fidelity simulations. This suggests that the numerical dissipation inherent in WENO schemes functions as a high-quality, implicit SGS closure for this stratocumulus case. Conversely, using oscillatory centered difference numerical schemes for momentum advection, WENO numerics for scalars, and explicitly modeled SGS fluxes consistently produces the lowest-fidelity simulations. We attribute this to the production of anomalously large SGS fluxes near the cloud tops through the interaction of numerical error in the momentum field with the scalar SGS model. © 2017. The Authors."
"55081793600;36660575800;7004974000;","Impact of Different Cumulus Parameterization Schemes in SAUDI-KAU AGCM",2017,"10.1007/s41748-017-0003-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031928014&doi=10.1007%2fs41748-017-0003-0&partnerID=40&md5=30fadf1d7d45a1f52080f8980e61d9da","Background: In global climate models (GCMs), the convection is parameterized, since the typical scale of this process is smaller than the model resolution. Purpose: This study examines the impact of two different cumulus parameterization schemes on the simulated climate using single-column model (SCM) as well as in an atmospheric global climate model (AGCM). Methods: The two schemes used are: the Simplified Arakawa–Schubert (SAS) scheme; and the Emanuel scheme coupled with a probability distribution function-based cloud parameterization scheme (EMAN). Results: The humidity, temperature, cloud fraction, and precipitation simulations are improved in EMAN as compared to that of SAS in SCM. Climatological simulations (1981-2014) conducted using an AGCM at a moderate resolution (T106L44: 1.125° × 1.125°) indicated that the use of the EMAN improved the results. The precipitation over the tropical belt also showed improvements in terms of the distributions, biases, and association with observation. These improvements are attributable to a better vertical structure of temperature, especially in the tropics, due to the more realistic estimation of the temperature and moisture fields by the EMAN. The error estimated in outgoing long-wave radiation for EMAN is lower than that of the SAS. The vertical structure of specific humidity and temperature shows less error in EMAN as compared to SAS. Conclusion: Results using the SCM and AGCM reveal the benefits of using the EMAN in comparison to the SAS which includes better simulation of the relative humidity, temperature, and precipitation fields. © 2017, Springer International Publishing Switzerland."
"57172833500;7003972559;","Monitoring aerosol-cloud interactions at the CESAR Observatory in the Netherlands",2017,"10.5194/amt-10-1987-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020028807&doi=10.5194%2famt-10-1987-2017&partnerID=40&md5=c1c0c1c6b1435841ffe51f226ec53feb","The representation of aerosol-cloud interaction (ACI) processes in climate models, although long studied, still remains the source of high uncertainty. Very often there is a mismatch between the scale of observations used for ACI quantification and the ACI process itself. This can be mitigated by using the observations from groundbased remote sensing instruments. In this paper we presented a direct application of the aerosol-cloud interaction monitoring technique (ACI monitoring). ACI monitoring is based on the standardised Cloudnet data stream, which provides measurements from ground-based remote sensing instruments working in synergy. For the data set collected at the CESAR Observatory in the Netherlands we calculate ACI metrics. We specifically use attenuated backscatter coefficient (ATB) for the characterisation of the aerosol properties and cloud droplet effective radius (re) and number concentration (Nd) for the characterisation of the cloud properties. We calculate two metrics: ACIr Dln(re)/ln(ATB) and ACIN Dln(Nd)/ln(ATB). The calculated values of ACIr range from 0.001 to 0.085, which correspond to the values reported in previous studies. We also evaluated the impact of the vertical Doppler velocity and liquid water path (LWP) on ACI metrics. The values of ACIr were highest for LWP values between 60 and 105 gm-2. For higher LWP other processes, such as collision and coalescence, seem to be dominant and obscure the ACI processes. We also saw that the values of ACIr are higher when only data points located in the updraught regime are considered. The method presented in this study allow for monitoring ACI daily and further aggregating daily data into bigger data sets. © Author(s) 2017."
"55717441600;55503023100;7004325649;7404075868;36816180700;8953038700;16645127300;56493740900;57193803894;7003854810;","Spectrally dependent CLARREO infrared spectrometer calibration requirement for climate change detection",2017,"10.1175/JCLI-D-16-0704.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019083569&doi=10.1175%2fJCLI-D-16-0704.1&partnerID=40&md5=1710eabd0f9d8aff513557d220110a44","Detecting climate trends of atmospheric temperature, moisture, cloud, and surface temperature requires accurately calibrated satellite instruments such as the Climate Absolute Radiance and Refractivity Observatory (CLARREO). Previous studies have evaluated the CLARREO measurement requirements for achieving climate change accuracy goals in orbit. The present study further quantifies the spectrally dependent IR instrument calibration requirement for detecting trends of atmospheric temperature and moisture profiles. The temperature, water vapor, and surface skin temperature variability and the associated correlation time are derived using the Modern-Era Retrospective Analysis for Research and Applications (MERRA) and European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis data. The results are further validated using climate model simulation results. With the derived natural variability as the reference, the calibration requirement is established by carrying out a simulation study for CLARREO observations of various atmospheric states under all-sky conditions. A 0.04-K (k = 2; 95% confidence) radiometric calibration requirement baseline is derived using a spectral fingerprinting method. It is also demonstrated that the requirement is spectrally dependent and that some spectral regions can be relaxed as a result of the hyperspectral nature of the CLARREO instrument. Relaxing the requirement to 0.06 K (k = 2) is discussed further based on the uncertainties associated with the temperature and water vapor natural variability and relatively small delay in the time to detect for trends relative to the baseline case. The methodology used in this study can be extended to other parameters (such as clouds and CO2) and other instrument configurations. © 2017 American Meteorological Society."
"7003777747;35547807400;6602988199;36894599500;23101759100;55757821600;24329376600;57203200427;12240390300;57110426700;56250250300;57189524073;7006462819;12139043600;7102976560;6602414959;57109884900;7004214645;7004942632;24472400800;7202079615;22986631300;7004861251;","PDRMIP: A precipitation driver and response model intercomparison project-protocol and preliminary results",2017,"10.1175/BAMS-D-16-0019.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021377597&doi=10.1175%2fBAMS-D-16-0019.1&partnerID=40&md5=c6b9579c0fa452fc90a1cb2a885a2ca2","In PDRMIP, 10 climate modeling groups have performed common idealized simulations to enhance our understanding of the impacts of various climate drivers on precipitation. A core set of global perturbation simulations and additional regional perturbation simulations has already been performed with initial results presented in this study and in Samset et al. (2016). PDRMIP consists of step-change experiments, but this process-based approach is highly valuable for understanding current and future precipitation changes. Precipitation changes are at the heart of two of the four questions related to the World Climate Research Programme's Grand Challenge on Clouds, Circulation and Climate Sensitivity (Bony et al. 2015) and frame many of the issues considered during the Grand Challenges on Water Availability (Trenberth and Asrar 2014) and Climate Extremes. The main PDRMIP results will be analyzed during 2016-18 to feed into the next Intergovernmental Panel on Climate Change's (IPCC) Sixth Assessment Report (AR6). The main PDRMIP results will be updated online (www.cicero.uio.no/en/PDRMIP) with information on how to obtain publicly available model output. A description of available data relevant to precipitation and the energy budget are given online. Finally, descriptions of ongoing PDRMIP analyses and activities are available online and we encourage further analyses based on the PDRMIP dataset to enhance our understanding of the diverse climate driver impacts on the energy budget and precipitation. © 2017 American Meteorological Society."
"36624257700;55924208000;","Ensemble superparameterization versus stochastic parameterization: A comparison of model uncertainty representation in tropical weather prediction",2017,"10.1002/2016MS000857","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019839431&doi=10.1002%2f2016MS000857&partnerID=40&md5=10d8b2e2f842e95d3ef0b8d19e259edf","Stochastic schemes to represent model uncertainty in the European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble prediction system has helped improve its probabilistic forecast skill over the past decade by both improving its reliability and reducing the ensemble mean error. The largest uncertainties in the model arise from the model physics parameterizations. In the tropics, the parameterization of moist convection presents a major challenge for the accurate prediction of weather and climate. Superparameterization is a promising alternative strategy for including the effects of moist convection through explicit turbulent fluxes calculated from a cloud-resolving model (CRM) embedded within a global climate model (GCM). In this paper, we compare the impact of initial random perturbations in embedded CRMs, within the ECMWF ensemble prediction system, with stochastically perturbed physical tendency (SPPT) scheme as a way to represent model uncertainty in medium-range tropical weather forecasts. We especially focus on forecasts of tropical convection and dynamics during MJO events in October–November 2011. These are well-studied events for MJO dynamics as they were also heavily observed during the DYNAMO field campaign. We show that a multiscale ensemble modeling approach helps improve forecasts of certain aspects of tropical convection during the MJO events, while it also tends to deteriorate certain large-scale dynamic fields with respect to stochastically perturbed physical tendencies approach that is used operationally at ECMWF. © 2017. The Authors."
"26028515700;14023953700;57205479513;57161892300;7003266014;","Large anomalies in lower stratospheric water vapour and ice during the 2015-2016 El Ninõ",2017,"10.1038/ngeo2961","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020193687&doi=10.1038%2fngeo2961&partnerID=40&md5=b848edc4a063c1b49d0780459942781f","The strong and unusual El Ninõ of 2015-2016 produced a remarkable perturbation to the hydrologic budget of the tropical tropopause layer (14-19 km). This region regulates stratospheric water vapour, which has a direct radiative impact on surface temperatures. To first order, the coldest tropical tropopause temperature regulates the amount of water vapour entering the stratosphere by controlling the amount of dehydration in the rising air. Here we show that tropical convective cloud ice and associated cirrus sublimating at unusually high altitudes might also have a role in stratospheric hydration. The 2015-2016 El Ninõ produced decadal record water vapour amounts in the tropical Western Pacific, coincident with warm tropopause temperature anomalies. In the Central Pacific, convective cloud ice was observed 2 km above the anomalously cold tropopause. A trajectory-based dehydration model based on two reanalysis temperature and wind fields can account for only about 0.5-0.6 ppmv of the ∼0.9 ppmv tropical lower stratospheric moistening observed during this event. This suggests that unresolved convective dynamics and/or associated sublimation of lofted ice particles also contributed to lower stratospheric moistening. These observations suggest that convective moistening could contribute to future climate change-induced stratospheric water vapour increases. © 2017 Macmillan Publishers Limited, part of Springer Nature."
"7006861646;35766145000;6506416572;","A simple model of the life cycle of mesoscale convective systems cloud shield in the tropics",2017,"10.1175/JCLI-D-16-0556.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019063110&doi=10.1175%2fJCLI-D-16-0556.1&partnerID=40&md5=580d134dd0a91e3a11f45d55006560cc","Mesoscale convective systems (MCSs) are important to the water and energy budget of the tropical climate and are essential ingredients of the tropical circulation. MCSs are readily observed in satellite infrared geostationary imagery as cloud clusters that evolve in time from small structures to well-organized large patches of cloud shield before dissipating. The MCS cloud shield is the result of a large ensemble of mesoscale dynamical, thermodynamical, and microphysical processes. This study shows that a simple parametric model can summarize the time evolution of the morphological characteristics of the cloud shield during the life cycle of the MCS. It consists of a growth-decay linear model of the cloud shield and is based on three parameters: the time of maximum extent, the maximum extent, and the duration of the MCS. It is shown that the time of maximum is frequently close to the middle of the life cycle and that the correlation between maximum extent and duration is strong all over the tropics. This suggests that 1 degree of freedom is left to summarize the life cycle of the MCS cloud shield. Such a model fits the observed MCS equally well, independent of the duration, size, location, and propagation characteristics, and its relevance is assessed for a large number of MCSs over three boreal summer periods over the whole tropical belt. The scaling of this simple model exhibits weak (strong) regional variability for the short- (long-) lived systems indicative of the primary importance of the internal dynamics of the systems to the large-scale environment for MCS sustainability. © 2017 American Meteorological Society."
"24329376600;55206018900;8633783900;56726831200;55715917500;","Effective radiative forcing from historical land use change",2017,"10.1007/s00382-016-3280-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982903346&doi=10.1007%2fs00382-016-3280-7&partnerID=40&md5=37f271ec3ec7644de52eb6471dae9364","The effective radiative forcing (ERF) from the biogeophysical effects of historical land use change is quantified using the atmospheric component of the Met Office Hadley Centre Earth System model HadGEM2-ES. The global ERF at 2005 relative to 1860 (1700) is −0.4 (−0.5) Wm−2, making it the fourth most important anthropogenic driver of climate change over the historical period (1860–2005) in this model and larger than most other published values. The land use ERF is found to be dominated by increases in the land surface albedo, particularly in North America and Eurasia, and occurs most strongly in the northern hemisphere winter and spring when the effect of unmasking underlying snow, as well as increasing the amount of snow, is at its largest. Increased bare soil fraction enhances the seasonal cycle of atmospheric dust and further enhances the ERF. Clouds are shown to substantially mask the radiative effect of changes in the underlying surface albedo. Coupled atmosphere–ocean simulations forced only with time-varying historical land use change shows substantial global cooling (dT = −0.35 K by 2005) and the climate resistance (ERF/dT = 1.2 Wm−2 K−1) is consistent with the response of the model to increases in CO2 alone. The regional variation in land surface temperature change, in both fixed-SST and coupled atmosphere–ocean simulations, is found to be well correlated with the spatial pattern of the forced change in surface albedo. The forcing-response concept is found to work well for historical land use forcing—at least in our model and when the forcing is quantified by ERF. Our results suggest that land-use changes over the past century may represent a more important driver of historical climate change then previously recognised and an underappreciated source of uncertainty in global forcings and temperature trends over the historical period. © 2016, Crown Copyright as represented by the Met Office."
"13007924700;7006359574;8511991900;7403063262;7102062952;57203776263;24491934500;7004462227;57189372185;7004040199;8871497700;13405658600;7006705919;26029605900;57196499374;7006027075;7410177774;7402781278;57206166579;36076994600;7006593624;6603268269;6506424404;56384666800;","Recent advances in understanding secondary organic aerosol: Implications for global climate forcing",2017,"10.1002/2016RG000540","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020713245&doi=10.1002%2f2016RG000540&partnerID=40&md5=f6a33447f3cae7159a94041b526e652d","Anthropogenic emissions and land use changes have modified atmospheric aerosol concentrations and size distributions over time. Understanding preindustrial conditions and changes in organic aerosol due to anthropogenic activities is important because these features (1) influence estimates of aerosol radiative forcing and (2) can confound estimates of the historical response of climate to increases in greenhouse gases. Secondary organic aerosol (SOA), formed in the atmosphere by oxidation of organic gases, represents a major fraction of global submicron-sized atmospheric organic aerosol. Over the past decade, significant advances in understanding SOA properties and formation mechanisms have occurred through measurements, yet current climate models typically do not comprehensively include all important processes. This review summarizes some of the important developments during the past decade in understanding SOA formation. We highlight the importance of some processes that influence the growth of SOA particles to sizes relevant for clouds and radiative forcing, including formation of extremely low volatility organics in the gas phase, acid-catalyzed multiphase chemistry of isoprene epoxydiols, particle-phase oligomerization, and physical properties such as volatility and viscosity. Several SOA processes highlighted in this review are complex and interdependent and have nonlinear effects on the properties, formation, and evolution of SOA. Current global models neglect this complexity and nonlinearity and thus are less likely to accurately predict the climate forcing of SOA and project future climate sensitivity to greenhouse gases. Efforts are also needed to rank the most influential processes and nonlinear process-related interactions, so that these processes can be accurately represented in atmospheric chemistry-climate models. ©2017. American Geophysical Union. All Rights Reserved."
"57037521500;14032501300;36193003800;56452644200;7004208584;","Evaluation of the global MODIS 30 arc-second spatially and temporally complete snow-free land surface albedo and reflectance anisotropy dataset",2017,"10.1016/j.jag.2017.01.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013077101&doi=10.1016%2fj.jag.2017.01.011&partnerID=40&md5=9ec6e26c7a7520d9b9263f12864ce62c","Land surface albedo is an essential variable for surface energy and climate modeling as it describes the proportion of incident solar radiant flux that is reflected from the Earth's surface. To capture the temporal variability and spatial heterogeneity of the land surface, satellite remote sensing must be used to monitor albedo accurately at a global scale. However, large data gaps caused by cloud or ephemeral snow have slowed the adoption of satellite albedo products by the climate modeling community. To address the needs of this community, we used a number of temporal and spatial gap-filling strategies to improve the spatial and temporal coverage of the global land surface MODIS BRDF, albedo and NBAR products. A rigorous evaluation of the gap-filled values shows good agreement with original high quality data (RMSE = 0.027 for the NIR band albedo, 0.020 for the red band albedo). This global snow-free and cloud-free MODIS BRDF and albedo dataset (established from 2001 to 2015) offers unique opportunities to monitor and assess the impact of the changes on the Earth's land surface. © 2017 The Author(s)"
"55687436600;55545601500;55805773500;8258673100;7202016984;7004378370;7004678728;7006577245;","Observations of Arctic snow and sea ice cover from CALIOP lidar measurements",2017,"10.1016/j.rse.2017.03.046","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017093480&doi=10.1016%2fj.rse.2017.03.046&partnerID=40&md5=f79eef0f0847d80780b3a9f709407b46","This paper describes the development and validation of a method to accurately identify snow/ice cover, surface melting, land surface and open water in polar regions using polar-orbiting Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) lidar measurements from the Cloud and Aerosol Lidar and Infrared Pathfinder Observation (CALIPSO) mission. The technique is based on the relationship between integrated attenuated backscatter color ratio and integrated depolarization ratio, and is proven to efficiently separate snow/ice cover and surface melting from open water and land surfaces. The method has been applied to 10 years (2006–2016) of CALIOP data to study the seasonal and inter-annual variability of Arctic sea ice cover and its declining trend. Results show that the area fraction of snow cover over land at latitudes > 60°N varied between 0.9 during winter and 0.1 in summer. The CALIOP observations of Arctic sea ice cover exhibit a strong seasonal cycle and significant inter-annual variability, which are consistent with the passive microwave-based sea ice results. The > 10 years of CALIOP continuous observations of the snow/ice cover will benefit the communities modeling snow/ice melting and climate change. © 2017 The Authors"
"57194199596;57210687618;7004247643;","Glacial inception on Baffin Island: The role of insolation, meteorology, and topography",2017,"10.1175/JCLI-D-16-0576.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019055706&doi=10.1175%2fJCLI-D-16-0576.1&partnerID=40&md5=e2f74af2f52dcd2cac7ec4c622725e71","Geologic evidence suggests that the last glacial inception (115 kya) occurred within the mountains of Baffin Island. Global climate models (GCMs) have difficulty simulating this climate transition, likely because of their coarse horizontal resolution that smooths topography and necessitates the use of cumulus parameterizations. A regional configuration of the Weather Research and Forecasting (WRF) Model is used to simulate the small-scale topographic and cloud processes neglected by GCMs, and the sensitivity of the region to Milankovitch forcing, topography, and meteorology is tested. It is found that ice growth is possible with 115-kya insolation, realistic topography, and slightly colder-than-average meteorology, represented by specific years within the past three decades. The simulation with low GCM-like topography shows a negative surface mass balance, even with the relevant orbital parameter configuration, demonstrating the criticality of realistic topography. The downslope growth of the ice sheets is studied by looking at the sensitivity of the mass balance to initial snow cover prescribed beyond that of the present day. It is found that the snow-albedo feedback, via its effects on the mass balance, allows such larger snow cover to persist. Implications for GCM studies of glacial inception are discussed. © 2017 American Meteorological Society."
"57190127262;37006854700;57194499087;57194383828;6604032554;","A postprocessing methodology for direct normal irradiance forecasting using cloud information and aerosol load forecasts",2017,"10.1175/JAMC-D-16-0297.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020433000&doi=10.1175%2fJAMC-D-16-0297.1&partnerID=40&md5=aa004ff179903f2ce510f1836ff4394b","A method for direct normal irradiance (DNI) forecasting for specific sites is proposed. It is based on the combination of a numerical weather prediction (NWP) model, which provides cloud information, with radiative transfer simulations fed with external aerosol forecasts. The NWP model used is the ECMWF Integrated Forecast System, and the radiative transfer information has been obtained from the Library of Radiative Transfer (libRadtran). Two types of aerosol forecasts have been tested: the global Monitoring Atmospheric Composition and Climate (MACC) model, which predicts five major components of aerosols, and the Dust Regional Atmospheric Model (BSC-DREAM8b) added to a fixed background calculated as the 20th percentile of the monthly mean of AERONET 2.0 observations from a different year. The methodology employed is valid for all meteorological situations, providing a stable and continuous DNI curve. The performance of the combined method has been evaluated against DNI observations and compared with the pure ECMWF forecasts at eight locations in the southern half of mainland Spain and the Canary Islands, which received high loadings of African dust for 2013 and 2014. Results for 1-day forecasts are presented. Although clouds play a major role, aerosols have a significant effect, but at shorter time scales. The combination of ECMWF and MACC forecasts gives the best global results, improving the DNI forecasts in events with high aerosol content. The regional BSC-DREAM8b yields good results for some extremely high dust conditions, although more reliable predictions, valid for any aerosol conditions, are provided by the MACC model. © 2017 American Meteorological Society."
"7003372313;","Nitrogen condensation in Titan's atmosphere under contemporary atmospheric composition",2017,"10.1016/j.icarus.2017.02.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013668351&doi=10.1016%2fj.icarus.2017.02.005&partnerID=40&md5=815f5dcf7257bd6727255239f86caa4e","Temperature profiles of Titan's atmosphere obtained by Cassini radio occultations approach the nitrogen condensation temperature curve at some places. This raises the question as to whether nitrogen, Titan's main atmospheric constituent, might condense in some seasons and areas contrary to previous perception. To address this question, possible areas and seasons of nitrogen condensation are searched for by a global climate model. The model is run under the present atmospheric pressure and composition but under various orbital configurations including the present one. Under the present orbital configuration the polar temperature at either pole becomes lowest around the northern autumnal equinox one season after aphelion. Liquid nitrogen clouds may appear in this season between 30 and 40  km altitude at least near the south pole, presumably embedded in icy methane clouds. Any falling nitrogen rain is likely to entirely evaporate before reaching the surface and thus does not affect the seasonal cycle of surface pressure. Seasonal nitrogen condensation is more frequent and intense when Saturn's orbital eccentricity is larger and hence the heliocentric distance at aphelion is larger. Nevertheless, orbital parameter variations alone are not capable of flooding the surface with liquid nitrogen or causing large fluctuations of the surface pressure. © 2017 Elsevier Inc."
"7202772927;7101801476;","The impact of simulated mesoscale convective systems on global precipitation: A multiscale modeling study",2017,"10.1002/2016MS000836","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017181738&doi=10.1002%2f2016MS000836&partnerID=40&md5=aee89950ae89e430182f81cc24e89320","The importance of precipitating mesoscale convective systems (MCSs) has been quantified from TRMM precipitation radar and microwave imager retrievals. MCSs generate more than 50% of the rainfall in most tropical regions. MCSs usually have horizontal scales of a few hundred kilometers (km); therefore, a large domain with several hundred km is required for realistic simulations of MCSs in cloud-resolving models (CRMs). Almost all traditional global and climate models do not have adequate parameterizations to represent MCSs. Typical multiscale modeling frameworks (MMFs) may also lack the resolution (4 km grid spacing) and domain size (128 km) to realistically simulate MCSs. The impact of MCSs on precipitation is examined by conducting model simulations using the Goddard Cumulus Ensemble (GCE, a CRM) model and Goddard MMF that uses the GCEs as its embedded CRMs. Both models can realistically simulate MCSs with more grid points (i.e., 128 and 256) and higher resolutions (1 or 2 km) compared to those simulations with fewer grid points (i.e., 32 and 64) and low resolution (4 km). The modeling results also show the strengths of the Hadley circulations, mean zonal and regional vertical velocities, surface evaporation, and amount of surface rainfall are weaker or reduced in the Goddard MMF when using more CRM grid points and higher CRM resolution. In addition, the results indicate that large-scale surface evaporation and wind feedback are key processes for determining the surface rainfall amount in the GMMF. A sensitivity test with reduced sea surface temperatures shows both reduced surface rainfall and evaporation. © 2017. The Authors."
"57193999542;6505932008;","Characterizing convective cold pools",2017,"10.1002/2016MS000788","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019028359&doi=10.1002%2f2016MS000788&partnerID=40&md5=c2657078d73646c47d522864c4ab89fd","Cold pools produced by convective storms play an important role in Earth's climate system. However, a common framework does not exist for objectively identifying convective cold pools in observations and models. The present study investigates convective cold pools within a simulation of tropical continental convection that uses a cloud-resolving model with a coupled land-surface model. Multiple variables are assessed for their potential in identifying convective cold pool boundaries, and a novel technique is developed and tested for identifying and tracking cold pools in numerical model simulations. This algorithm is based on surface rainfall rates and radial gradients in the density potential temperature field. The algorithm successfully identifies near-surface cold pool boundaries and is able to distinguish between connected cold pools. Once cold pools have been identified and tracked, composites of cold pool evolution are then constructed, and average cold pool properties are investigated. Wet patches are found to develop within the centers of cold pools where the ground has been soaked with rainwater. These wet patches help to maintain cool surface temperatures and reduce cold pool dissipation, which has implications for the development of subsequent convection. © 2017. The Authors."
"36057442400;22980035400;","Simulated polarimetric fields of ice vapor growth using the adaptive habit model. Part II: A case study from the FROST experiment",2017,"10.1175/MWR-D-16-0062.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020107027&doi=10.1175%2fMWR-D-16-0062.1&partnerID=40&md5=ef121d3b15cfdcef8bdb6adda8f615da","A new adaptive habit model (AHM) grows ice crystals through vapor deposition while evolving ice particle properties, including shape and effective density. The AHM provides an opportunity to investigate observed microphysical processes through the computation of polarimetric variables and corroboration with microphysical model output. This study is unique because the polarimetric scattering calculations are computed using predicted microphysical parameters rather than a priori assumptions that are imposed within the scattering calculations in the forward simulator, allowing for a more effective comparison to radar observations. Through the simulation of a case in the Front Range of the Rocky Mountains in Colorado using the Advanced Research version of the Weather Research and Forecasting Model, it is found that the AHM approximates ice mass, shape, cloud vertical structure, and temporal evolution as reflected through polarimetric quantities compared to observations. AHM reflectivity magnitudes are similar to those observed with radar and are an improvement over spherical ice crystal assumptions. Further analyses are completed to examine the effect of microphysical processes on the evolution of the differential reflectivity and specific differential phase, both of which are simulated using the AHM. Simulations reveal a polarimetric response to ice crystal mass, number, size, density, and aspect ratio. While results reveal the need for model improvements (e.g., parameterizations for aggregation rate), testing forward-simulated radar fields against observations is a first step in the validation of model microphysical and precipitation processes. © 2017 American Meteorological Society."
"55462884000;56612517400;36538539800;","Improving organic aerosol treatments in CESM/CAM5: Development, application, and evaluation",2017,"10.1002/2016MS000874","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007436816&doi=10.1002%2f2016MS000874&partnerID=40&md5=765ff3d7fb6466ed7d089207ac5711ad","New treatments for organic aerosol (OA) formation have been added to a modified version of the CESM/CAM5 model (CESM-NCSU). These treatments include a volatility basis set treatment for the simulation of primary and secondary organic aerosols (SOAs), a simplified treatment for organic aerosol (OA) formation from glyoxal, and a parameterization representing the impact of new particle formation (NPF) of organic gases and sulfuric acid. With the inclusion of these new treatments, the concentration of oxygenated organic aerosol increases by 0.33 µg m−3 and that of primary organic aerosol (POA) decreases by 0.22 µg m−3 on global average. The decrease in POA leads to a reduction in the OA direct effect, while the increased OOA increases the OA indirect effects. Simulations with the new OA treatments show considerable improvement in simulated SOA, oxygenated organic aerosol (OOA), organic carbon (OC), total carbon (TC), and total organic aerosol (TOA), but degradation in the performance of HOA. In simulations of the current climate period, despite some deviations from observations, CESM-NCSU with the new OA treatments significantly improves the magnitude, spatial pattern, seasonal pattern of OC and TC, as well as, the speciation of TOA between POA and OOA. Sensitivity analysis reveals that the inclusion of the organic NPF treatment impacts the OA indirect effects by enhancing cloud properties. The simulated OA level and its impact on the climate system are most sensitive to choices in the enthalpy of vaporization and wet deposition of SVOCs, indicating that accurate representations of these parameters are critical for accurate OA-climate simulations. © 2017. The Authors."
"55512674800;6603652793;55470017900;43561848300;35302065900;","A conceptual model for development of intense pyrocumulonimbus in western North America",2017,"10.1175/MWR-D-16-0232.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013203568&doi=10.1175%2fMWR-D-16-0232.1&partnerID=40&md5=b79f3f91e5252d28e1adc24f12bef42f","The first observationally based conceptual model for intense pyrocumulonimbus (pyroCb) development is described by applying reanalyzed meteorological model output to an inventory of 26 intense pyroCb events from June to August 2013 and a control inventory of intense fire activity without pyroCb. Results are based on 88 intense wildfires observed within the western United States and Canada. While surface-based fire weather indices are a useful indicator of intense fire activity, they are not a skillful predictor of intense pyroCb. Development occurs when a layer of increased moisture content and instability is advected over a dry, deep, and unstable mixed layer, typically along the leading edge of an approaching disturbance or under the influence of a monsoonal anticyclone. Upper-tropospheric dynamics are conducive to rising motion and vertical convective development. Mid- and upper-tropospheric conditions therefore resemble those that produce traditional dry thunderstorms. The specific quantity of midlevel moisture and instability required is shown to be strongly dependent on the surface elevation of the contributing fire. Increased thermal buoyancy from large and intense wildfires can serve as a potential trigger, implying that pyroCb occasionally develop in the absence of traditional meteorological triggering mechanisms. This conceptual model suggests that meteorological conditions favorable for pyroCb are observed regularly in western North America. PyroCb and ensuing stratospheric smoke injection are therefore likely to be significant and endemic features of summer climate. Results from this study provide a major step toward improved detection, monitoring, and prediction of pyroCb, which will ultimately enable improved understanding of the role of this phenomenon in the climate system. © 2017 American Meteorological Society."
"57202656048;55664151400;12039404800;","Key drivers controlling the stable isotopes in precipitation on the leeward side of the central Himalayas",2017,"10.1016/j.atmosres.2017.01.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012285799&doi=10.1016%2fj.atmosres.2017.01.020&partnerID=40&md5=03aaf3a982600e7b68492f5fe94b576a","The Himalayas, as a barrier to the monsoonal moisture transport, cause an arid climate on the leeward side. This study investigates the mechanisms of isotopic variations in precipitation on the leeward side of the central Himalayas. Data of Xigaze, which is just north of the central Himalayas, suggest precipitation falls overwhelmingly in the summer monsoon season and subcloud evaporation plays an important role in altering the stable isotopes in precipitation due to the arid climate. Precipitation at Xigaze demonstrates a significant isotopic amount effect, whereby there is a significantly negative correlation between rainfall amount and δ18O. Such a result is found to partly arise from the effect of subcloud evaporation, as reflected by increasing evaporative signatures (higher δ18O but lower d-excess (d-excess = δD-8δ18O)) in rainfall with decreasing rainfall amount. Spatially, a pseud-altitude effect on precipitation δ18O and d-excess is observed on the leeward side of the central Himalayas. Lower d-excess but higher δ18O in precipitation are found at Xigaze than at Tingri, and this is likely caused by the stronger subcloud evaporation at the lower-altitude site of Xigaze due to its longer descent distance from the cloud base to the ground rather than the rainout process. Additionally, a synoptic survey of streamwaters across the central Himalayas helps to confirm that the spatial variation in isotopic values of precipitation is closely related to the difference in moisture source between windward and leeward sides and the degree of subcloud evaporation on the leeward side. These findings augment our understanding of local- to regional-scale hydroclimate in the central Himalayas. © 2017 Elsevier B.V."
"57040141000;57164106400;7408519295;35209683700;26324818700;","Process-based decomposition of the decadal climate difference between 2002-13 and 1984-95",2017,"10.1175/JCLI-D-15-0742.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020001048&doi=10.1175%2fJCLI-D-15-0742.1&partnerID=40&md5=4f758e79eb7abb9379440a03f727c7e5","This study examines at the process level the climate difference between 2002-13 and 1984-95 in ERA-Interim. A linearized radiative transfer model is used to calculate the temperature change such that its thermal radiative cooling would balance the energy flux perturbation associated with the change of an individual process, without regard to what causes the change of the process in the first place. The global mean error of the offline radiative transfer model calculations is 0.09 K, which corresponds to the upper limit of the uncertainties from a single term in the decomposition analysis. The process-based decomposition indicates that the direct effect of the increase of CO2 (0.15 K) is the largest contributor to the global warming between the two periods (about 0.27 K). The second and third largest contributors are the cloud feedback (0.14 K) and the combined effect of the oceanic heat storage and evaporation terms (0.11 K), respectively. The largest warming associated with the oceanic heat storage term is found in the tropical Pacific and Indian Oceans, with relatively weaker warming over the tropical Atlantic Ocean. The increase in atmospheric moisture adds another 0.1 K to the global surface warming, but the enhancement in tropical convections acts to reduce the surface warming by 0.17 K. The ice-albedo and atmospheric dynamical feedbacks are the two leading factors responsible for the Arctic polar warming amplification (PWA). The increase of atmospheric water vapor over the Arctic region also contributes substantially to the Arctic PWA pattern. © 2017 American Meteorological Society."
"57198945375;57203579757;57000410500;","Design and implementation of a GSI-based convection-allowing ensemble-based data assimilation and forecast system for the PECAN field experiment. Part II: Overview and evaluation of a real-time system",2017,"10.1175/WAF-D-16-0201.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020029341&doi=10.1175%2fWAF-D-16-0201.1&partnerID=40&md5=053a30cb7939aadf73d292f2c5185f3d","Multiscale ensemble-based data assimilation and forecasts were performed in real time during the Plains Elevated Convection At Night (PECAN) field experiment. A 20-member ensemble of forecasts at 4-km grid spacing was initialized daily at both 1300 and 1900 UTC, together with a deterministic forecast at 1-km grid spacing initialized at 1300 UTC. The configuration of the GSI-based data assimilation and forecast system was guided by results presented in Part I of this two-part study. The present paper describes the implementation of the real-time system and the extensive forecast products that were generated to support the unique interests of PECAN researchers. Subjective and objective verification of the real-time forecasts from 1 June through 15 July 2015 is conducted, with an emphasis on nocturnal mesoscale convective systems (MCSs), nocturnal convective initiation (CI), nocturnal low-level jets (LLJs), and bores on the nocturnal stable layer. Verification of nocturnal precipitation during overnight hours, a proxy for MCSs, shows both greater skill and spread for the 1300 UTC forecasts than the 1900 UTC forecasts. Verification against observed soundings reveals that the forecast LLJs systematically peak, veer, and dissipate several hours before the observations. Comparisons with bores that passed over an Atmospheric Emitted Radiance Interferometer reveal an ability to predict borelike features that is greatly improved at 1-km, compared with 4-km, grid spacing. Objective verification of forecast CI timing reveals strong sensitivity to the PBL scheme but an overall unbiased ensemble. © 2017 American Meteorological Society."
"28367935500;57205867148;7201504886;35509639400;57203200427;10139397300;15042618500;8866821900;42263280300;55796506900;","Fast and slow shifts of the zonal-mean intertropical convergence zone in response to an idealized anthropogenic aerosol",2017,"10.1002/2016MS000902","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018831364&doi=10.1002%2f2016MS000902&partnerID=40&md5=73c99883fd3c3fb8bdc613bbbc60d206","Previous modeling work showed that aerosol can affect the position of the tropical rain belt, i.e., the intertropical convergence zone (ITCZ). Yet it remains unclear which aspects of the aerosol impact are robust across models, and which are not. Here we present simulations with seven comprehensive atmosphere models that study the fast and slow impacts of an idealized anthropogenic aerosol on the zonal-mean ITCZ position. The fast impact, which results from aerosol atmospheric heating and land cooling before sea-surface temperature (SST) has time to respond, causes a northward ITCZ shift. Yet the fast impact is compensated locally by decreased evaporation over the ocean, and a clear northward shift is only found for an unrealistically large aerosol forcing. The local compensation implies that while models differ in atmospheric aerosol heating, this does not contribute to model differences in the ITCZ shift. The slow impact includes the aerosol impact on the ocean surface energy balance and is mediated by SST changes. The slow impact is an order of magnitude more effective than the fast impact and causes a clear southward ITCZ shift for realistic aerosol forcing. Models agree well on the slow ITCZ shift when perturbed with the same SST pattern. However, an energetic analysis suggests that the slow ITCZ shifts would be substantially more model-dependent in interactive-SST setups due to model differences in clear-sky radiative transfer and clouds. We also discuss implications for the representation of aerosol in climate models and attributions of recent observed ITCZ shifts to aerosol. © 2017. The Authors."
"57194420030;7006306835;7103206141;56744278700;55271575700;","On the seasonality of arctic black carbon",2017,"10.1175/JCLI-D-16-0580.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020040253&doi=10.1175%2fJCLI-D-16-0580.1&partnerID=40&md5=b001b3e811d3ef004102d80b4251ccb6","Arctic haze has a distinct seasonal cycle with peak concentrations in winter but pristine conditions in summer. It is demonstrated that the Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric general circulation model (AM3) can reproduce the observed seasonality of Arctic black carbon (BC), an important component of Arctic haze. The model is used to study how large-scale circulation and removal drive the seasonal cycle of Arctic BC. It is found that despite large seasonal shifts in the general circulation pattern, the transport of BC into the Arctic varies little throughout the year. The seasonal cycle of Arctic BC is attributed mostly to variations in the controlling factors of wet removal, namely the hydrophilic fraction of BC and wet deposition efficiency of hydrophilic BC. Specifically, a confluence of low hydrophilic fraction and weak wet deposition, owing to slower aging process and less efficient mixed-phase cloud scavenging, respectively, is responsible for the wintertime peak of BC. The transition to low BC in summer is the consequence of a gradual increase in the wet deposition efficiency, whereas the increase of BC in late fall can be explained by a sharp decrease in the hydrophilic fraction. The results presented here suggest that future changes in the aging and wet deposition processes can potentially alter the concentrations of Arctic aerosols and their climate effects. © 2017 American Meteorological Society."
"7101964663;6506761906;7003480967;29067768100;","The unusual early morning Tornado in Ciudad Acuña, Coahuila, Mexico, on 25 May 2015",2017,"10.1175/MWR-D-16-0252.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020091868&doi=10.1175%2fMWR-D-16-0252.1&partnerID=40&md5=05105334fe73d1dfae0629264dc72fba","This study analyzes the synoptic- andmesoscale conditions present during initiation and intensification of the supercell thunderstormthat produced a tornado inCiudadAcuña, a community located in the state ofCoahuila, Mexico, 10 km southwest of the U.S. border. Early morning convective activity, first detected by radar at 0628 UTC 25 May 2015, developed into an intense and well-defined supercell thunderstorm that produced a tornado between approximately 1045 and 1130 UTC. Hourly analyses from the Rapid Refresh model indicated an upslope component to surface flow in the region of convection initiation over the Serranías del Burro (SdB). Along the storm's trajectory, dewpoint temperatures increased from15° to 22 ° C, convective available potential energy increased from1500 to near 4000 J kg-1, and convective inhibition changed from-150 J kg-1 at the time of convection initiation to near zero in CiudadAcuña. Simulations fromthe Weather Research and Forecasting Model confirmed the sensitivity of both convection initiation and stormintensification to the topography of the SdB. In the control simulation and two simulations in which topography was reduced in elevation, a cluster of storms formed and intensified over the centralmountains. However, when topography was further reduced and the SdB region became a large flat plain, little convective activity was seen, forming only along the dryline without intensifying or propagating to the east as was observed. © 2017 American Meteorological Society."
"6603900587;24075297800;54401287500;7005140378;36602109100;6701844654;56105640400;11141657700;7101775250;6507119209;8442845600;","Area-based vs tree-centric approaches to mapping forest carbon in Southeast Asian forests from airborne laser scanning data",2017,"10.1016/j.rse.2017.03.017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016244233&doi=10.1016%2fj.rse.2017.03.017&partnerID=40&md5=5d47057ed42a592c17876801f52c393d","Tropical forests are a key component of the global carbon cycle, and mapping their carbon density is essential for understanding human influences on climate and for ecosystem-service-based payments for forest protection. Discrete-return airborne laser scanning (ALS) is increasingly recognised as a high-quality technology for mapping tropical forest carbon, because it generates 3D point clouds of forest structure from which aboveground carbon density (ACD) can be estimated. Area-based models are state of the art when it comes to estimating ACD from ALS data, but discard tree-level information contained within the ALS point cloud. This paper compares area-based and tree-centric models for estimating ACD in lowland old-growth forests in Sabah, Malaysia. These forests are challenging to map because of their immense height. We compare the performance of (a) an area-based model developed by Asner and Mascaro (2014), and used primarily in the neotropics hitherto, with (b) a tree-centric approach that uses a new algorithm (itcSegment) to locate trees within the ALS canopy height model, measures their heights and crown widths, and calculates biomass from these dimensions. We find that Asner and Mascaro's model needed regional calibration, reflecting the distinctive structure of Southeast Asian forests. We also discover that forest basal area is closely related to canopy gap fraction measured by ALS, and use this finding to refine Asner and Mascaro's model. Finally, we show that our tree-centric approach is less accurate at estimating ACD than the best-performing area-based model (RMSE 18% vs 13%). Tree-centric modelling is appealing because it is based on summing the biomass of individual trees, but until algorithms can detect understory trees reliably and estimate biomass from crown dimensions precisely, areas-based modelling will remain the method of choice. © 2017 The Authors"
"35829347100;35187765600;55576263100;8233574300;6701496997;6701642652;","An enhanced satellite-based algorithm for detecting and tracking dust outbreaks by means of SEVIRI data",2017,"10.3390/rs9060537","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021116703&doi=10.3390%2frs9060537&partnerID=40&md5=7a72650c6048e72d4bd39f111c14cf58","Dust outbreaks are meteorological phenomena of great interest for scientists and authorities (because of their impact on the climate, environment, and human activities), which may be detected, monitored, and characterized from space using different methods and procedures. Among the recent dust detection algorithms, the RSTDUST multi-temporal technique has provided good results in different geographic areas (e.g., Mediterranean basin; Arabian Peninsula), exhibiting a better performance than traditional split window methods, in spite of some limitations. In this study, we present an optimized configuration of this technique, which better exploits data provided by Spinning Enhanced Visible and Infrared Imager (SEVIRI) aboard Meteosat Second Generation (MSG) satellites to address those issues (e.g., sensitivity reduction over arid and semi-arid regions; dependence on some meteorological clouds). Three massive dust events affecting Europe and the Mediterranean basin in May 2008/2010 are analysed in this work, using information provided by some independent and well-established aerosol products to assess the achieved results. The study shows that the proposed algorithm, christened eRSTDUST (i.e., enhanced RSTDUST), which provides qualitative information about dust outbreaks, is capable of increasing the trade-off between reliability and sensitivity. The results encourage further experimentations of this method in other periods of the year, also exploiting data provided by different satellite sensors, for better evaluating the advantages arising from the use of this dust detection technique in operational scenarios. © 2017 by the authors."
"56218128100;56270367000;8967845400;","Upper-ocean contribution to short-term regional coastal sea level variability along the United States",2017,"10.1175/JCLI-D-16-0896.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019070288&doi=10.1175%2fJCLI-D-16-0896.1&partnerID=40&md5=a14511727430c75a3c3d9485fcf4e93d","The upper ocean thermal structure is largely influenced by natural internal variability, and it modulates global surface temperature as well as regional sea level anomalies over decadal time scales. The internal variability of some important oceanographic processes, such as the Pacific decadal oscillation, can cause differences of 10 to 20 cm relative to the global mean in many coastal locations. These differences are sufficient to alter decisions between soft and/or large protective measures on every coast. Yet, current indicators of sea level changes are based on either surface variables or subsurface ocean measurements through the entire water column. There is also a lack of focus on short-term predictions of sea level change and concrete applications of these predictions at regional scale, which clouds local decision-making. The results herein confirm that the information contained within the top 300 m of the ocean is essential to capture decadal, regional relative sea level variability, whereas depths well below the thermocline do not appear to be closely tied to these large oscillations. Hence, the authors propose a regionally scoped indicator based on upper-ocean temperature as a first step toward identifying trend changes in short-term sea level rise over large coastal regions of the United States. The proposed indicator is a promising new tool that could help close the gaps mentioned above and improve the utility of existing local sea level records. © 2017 American Meteorological Society."
"57191341169;57192695511;7404061081;55706282100;7404548584;","MODIS retrieval of aerosol optical depth over turbid coastalwater",2017,"10.3390/rs9060595","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021057843&doi=10.3390%2frs9060595&partnerID=40&md5=d7873c7755282f79733bdcc7951aced9","We present a new approach to retrieve Aerosol Optical Depth (AOD) using the Moderate Resolution Imaging Spectroradiometer (MODIS) over the turbid coastal water. This approach supplements the operational Dark Target (DT) aerosol retrieval algorithm that currently does not conduct AOD retrieval in shallow waters that have visible sediments or sea-floor (i.e., Class 2 waters). Over the global coastal water regions in cloud-free conditions, coastal screening leads to ~20% unavailability of AOD retrievals. Here, we refine the MODIS DT algorithm by considering that water-leaving radiance at 2.1 μmto be negligible regardless of water turbidity, and therefore the 2.1 μm reflectance at the top of the atmosphere is sensitive to both change of fine-mode and coarse-mode AODs. By assuming that the aerosol single scattering properties over coastal turbid water are similar to those over the adjacent open-ocean pixels, the new algorithm can derive AOD over these shallow waters. The test algorithm yields ~18% more MODIS-AERONET collocated pairs for six AERONET stations in the coastal water regions. Furthermore, comparison of the new retrieval with these AERONET observations show that the new AOD retrievals have equivalent or better accuracy than those retrieved by the MODIS operational algorithm's over coastal land and non-turbid coastal water product. Combining the new retrievals with the existing MODIS operational retrievals yields an overall improvement of AOD over those coastal water regions. Most importantly, this refinement extends the spatial and temporal coverage of MODIS AOD retrievals over the coastal regions where 60% of human population resides. This expanded coverage is crucial for better understanding of impact of anthropogenic aerosol particles on coastal air quality and climate. © 2017 by the authors."
"22236015300;6602515941;7003665609;7102643810;6602084783;7005071296;","Microphysical properties of snow and their link to Ze-S relations during BAECC 2014",2017,"10.1175/JAMC-D-16-0379.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020452771&doi=10.1175%2fJAMC-D-16-0379.1&partnerID=40&md5=5fcf2e07662221e216a57e1920560464","This study uses snow events from the Biogenic Aerosols-Effects on Clouds and Climate (BAECC) 2014 campaign to investigate the connection between properties of snow and radar observations. The general hydrodynamic theory is applied to video-disdrometer measurements to retrieve masses of falling ice particles. Errors associated with the observation geometry and themeasured particle size distribution (PSD) are addressed by devising a simple correction procedure. The value of the correction factor is determined by comparison of the retrieved precipitation accumulation with weighing-gauge measurements. Derived mass-dimensional relations are represented in the power-law form m 5 amDbm. It is shown that the retrieved prefactor am and exponent bm react to changes in prevailingmicrophysical processes. From the derivedmicrophysical properties, event-specific relations between the equivalent reflectivity factor Ze and snowfall precipitation rate S (Ze 5 azsSbzs) are determined. For the studied events, the prefactor of the Ze-S relation varied between 53 and 782 and the exponent was in the range of 1.19-1.61. The dependence of the factors azs and bzs on the m(D) relation and PSD are investigated. The exponent of the Ze-S relation mainly depends on the exponent of the m(D) relation, whereas the prefactor azs depends on both the intercept parameter N0 of the PSDand the prefactors of them(D) andy(D) relations. Changes in azs for a given N0 are shown to be linked to changes in liquid water path, which can be considered to be a proxy for degree of riming. © 2017 American Meteorological Society."
"7401984344;7103267885;24482355000;15319682800;6602078681;6602458644;","Assessment of NUCAPS S-NPP CrIS/ATMS sounding products using reference and conventional radiosonde observations",2017,"10.1109/JSTARS.2017.2670504","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014853250&doi=10.1109%2fJSTARS.2017.2670504&partnerID=40&md5=bb0a0aab0560ea2c0ed5486b95ef8396","The NOAA unique combined atmospheric processing system (NUCAPS) sounding products derived from Suomi national polar-orbiting partnership (S-NPP) cross track infrared sounder/advanced technology microwave sounder (CrIS/ATMS) are assessed. This is done using collocated radiosondes from reference sites (i.e., global reference upper air network and satellite synchronized launch sites) and conventional upper air observing sites as the target data. Analysis of satellite retrieval bias and root-meansquare (rms) error, conducted on a global scale and at individual sites with representative climate regimes, indicates the NUCAPS temperature and water vapor retrieval performance meets the operational uncertainty requirements. Caution, however, is needed in this type of approach. In our empirical analyses, we find that the satellite retrieval rms error is sensitive to 1) the time mismatch in radiosonde launch and satellite overpass, particularly near the surface and tropopause for temperature and around the midtroposphere for water vapor, 2) vertical resolution differences between the satellite retrieval and radiosonde that become manifested as a larger rms error in the vicinity of the planetary boundary layer and tropopause, and 3) the accuracy of radiosonde water vapor measurements particularly in the upper troposphere and lower stratosphere where dry bias are prevalent. Examples highlighting these issues in the context of satellite data calibration and validation are provided. © 2017 IEEE."
"57193230617;7004337213;","Developing a Dust Emission Procedure for Central Asia",2017,"10.1177/1178622117711939","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044634333&doi=10.1177%2f1178622117711939&partnerID=40&md5=f3dd6d5c4cc8343848a7e5b0cfa79cc0","Airborne mineral dust is thought to have a significant influence on the climate through absorbing and scattering both shortwave and longwave radiations and affecting cloud microphysical processes. However, a knowledge of long-term dust emissions is limited from both temporal and spatial perspectives. Here, we have developed a quantitative climatology: the column-integrated mass of the dust aerosol loading in Central Asia by incorporating the dust module (DuMo) into the Weather Research and Forecasting coupled with Chemistry (WRF-Chem) model and accounting for regional climate and Land-Cover and Land-Use Changes for the 1950-2010 period in April. This data set is lowly to moderately correlated (0.22-0.48) with the satellite Aerosol Optical Depth in April of the 2000s and lowly correlated (0.02-0.11) with the Absorbing Aerosol Index in April of the 1980s, 1990s, and 2000s. The total dust loading is approximately 207.85 Mton per month in April during the recent decade (2000-2014) over dust source regions. Although only the month of April was simulated, results suggest that trends and magnitudes are captured well, using the WRF-Chem-DuMo. © 2017, © The Author(s) 2017."
"55945196100;21933618400;7006235542;7006377579;","Ice lollies: An ice particle generated in supercooled conveyor belts",2017,"10.1002/2017GL073441","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019565727&doi=10.1002%2f2017GL073441&partnerID=40&md5=52fe70e61ca9a43a0d13c941ace88f39","On 21 January 2009, a maturing low-pressure weather system approached the UK along with several associated frontal systems. As a part of the Aerosol Properties, PRocesses And InfluenceS on the Earth's climate-Clouds project, an observational research flight took place in southern England, sampling the leading warm front of this system. During the flight, a distinctive hydrometeor type was repeatedly observed which has not been widely reported in previous studies. We refer to the hydrometeors as “drizzle-rimed columnar ice” or “ice lollies” for short due to their characteristic shape. We discuss the processes that led to their formation using in situ and remote sensing data. ©2017. The Authors."
"56237235700;23491844400;9036557400;56927733700;56224155200;","Detection of deterministic and probabilistic convection initiation using Himawari-8 Advanced Himawari Imager data",2017,"10.5194/amt-10-1859-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019910702&doi=10.5194%2famt-10-1859-2017&partnerID=40&md5=d3f062cae281def22c0bd1a097d0f009","The detection of convective initiation (CI) is very important because convective clouds bring heavy rainfall and thunderstorms that typically cause severe socio-economic damage. In this study, deterministic and probabilistic CI detection models based on decision trees (DT), random forest (RF), and logistic regression (LR) were developed using Himawari-8 Advanced Himawari Imager (AHI) data obtained from June to August 2016 over the Korean Peninsula. A total of 12 interest fields that contain brightness temperature, spectral differences of the brightness temperatures, and their time trends were used to develop CI detection models. While, in our study, the interest field of 11.2 μm Tb was considered the most crucial for detecting CI in the deterministic models and the probabilistic RF model, the trispectral difference, i.e. (8.6-11.2 μm)-(11.2-12.4 μm), was determined to be the most important one in the LR model. The performance of the four models varied by CI case and validation data. Nonetheless, the DT model typically showed higher probability of detection (POD), while the RF model produced higher overall accuracy (OA) and critical success index (CSI) and lower false alarm rate (FAR) than the other models. The CI detection of the mean lead times by the four models were in the range of 20-40 min, which implies that convective clouds can be detected 30 min in advance, before precipitation intensity exceeds 35 dBZ over the Korean Peninsula in summer using the Himawari-8 AHI data. © Author(s) 2017. CC Attribution 3.0 License."
"35221494300;55515976300;57194329306;16444232500;7003968166;57203053317;","Effect of anthropogenic aerosol emissions on precipitation in warm conveyor belts in the western North Pacific in winter - A model study with ECHAM6-HAM",2017,"10.5194/acp-17-6243-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019713978&doi=10.5194%2facp-17-6243-2017&partnerID=40&md5=aeb7a680161264806f2172f35f340fb5","While there is a clear impact of aerosol particles on the radiation balance, whether and how aerosol particles influence precipitation is controversial. Here we use the ECHAM6-HAM global climate model coupled to an aerosol module to analyse whether an impact of anthropogenic aerosol particles on the timing and amount of precipitation can be detected in North Pacific warm conveyor belts. Warm conveyor belts are the strongest precipitation-producing airstreams in extratropical cyclones and are identified here with a Lagrangian technique, i.e. by objectively identifying the most strongly ascending trajectories in North Pacific cyclones. These conveyor belts have been identified separately in 10-year ECHAM6-HAM simulations with present-day and pre-industrial aerosol conditions. Then, the evolution of aerosols and cloud properties has been analysed in detail along the identified warm conveyor belt trajectories. The results show that, under present-day conditions, some warm conveyor belt trajectories are strongly polluted (i.e. high concentrations of black carbon and sulfur dioxide) due to horizontal transport from eastern Asia to the oceanic region where warm conveyor belts start their ascent. In these polluted trajectories a weak delay and reduction of precipitation formation occurs compared to clean warm conveyor belt trajectories. However, all warm conveyor belts consist of both polluted and clean trajectories at the time they start their ascent, and the typically more abundant clean trajectories strongly reduce the aerosol impact from the polluted trajectories. The main conclusion then is that the overall amount of precipitation is comparable in pre-industrial conditions, when all warm conveyor belt trajectories are clean, and in present-day conditions, when warm conveyor belts consist of a mixture of clean and polluted trajectories. © Author(s) 2017. CC Attribution 3.0 License."
"7102193013;","Future changes in global precipitation projected by the atmospheric model MRI-AGCM3.2H with a 60-km size",2017,"10.3390/atmos8050093","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019890493&doi=10.3390%2fatmos8050093&partnerID=40&md5=f6aac65f5534b71e95e86431b35d2497","We conducted global warming projections using the Meteorological Research Institute-Atmospheric General CirculationModel Version 3.2with a 60-kmgrid size (MRI-AGCM3.2H). For the present-day climate of 21 years from 1983 through 2003, the model was forced with observed historical sea surface temperature (SST). For the future climate of 21 years from 2079-2099, the model was forced with future SST projected by conventional couple models. Twelve-member ensemble simulations for three different cumulus convection schemes and four different SST distributions were conducted to evaluate the uncertainty of projection. Annual average precipitation will increase over the equatorial regions and decrease over the subtropical regions. The future precipitation changes are generally sensitive to the cumulus convection scheme, but changes are influenced by the SST over the some regions of the Pacific Ocean. The precipitation efficiency defined as precipitation change per 1° surface air temperature warming is evaluated. The global average of precipitation efficiency for annual average precipitation was less than the maximum value expected by thermodynamical theory, indicating that dynamical atmospheric circulation is acting to reduce the conversion efficiency from water vapor to precipitation. The precipitation efficiency by heavy precipitation is larger than that by moderate and weak precipitation. © 2017 by the author."
"36798418200;7004605766;8967864300;7003312142;6602802632;","Using a small COTS UAV to quantify moraine dynamics induced by climate shift in Arctic environments",2017,"10.1080/01431161.2016.1249310","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994112050&doi=10.1080%2f01431161.2016.1249310&partnerID=40&md5=b69f29a948420543a6143c2ff914f0c6","Arctic regions are known to be places where climate shift yields the most visible consequences. In this context, glaciers and their environment are highly subject to global warming effects. New dynamics are observed and the behaviour of arctic systems (such as glaciers, moraines, beaches, etc.) changes at rates visible over yearly observations. According to recent works on climate change impacts on the cryosphere, short/violent events are recently observed and are one characteristic of these changes. As a consequence, an accelerating rate of glacial and pro-glacial activity is observed, especially at the end of each hydrological season (early fall). As an example, many phases of streamflow increase/decrease are observed, transforming glacier outflows, moraine morphology, and re-organizing intra-moraine processes. Within only a few days, the morphology of some parts of the moraine can be completely changed. In order to observe and quantify these processes, reactive methods of survey are needed. That is why the use of commercial off the shelf–DJI Phantom3 Professional–unmanned aerial vehicle (UAV) for aerial photography acquisition combined with structure from motion analysis and digital elevation model computation were chosen. The robust architecture of this platform makes it well suited as a reliable picture acquisition system for high resolution (sub-decimetre) imaging. These increasingly popular methods, at a convergence of technologies including inertial guidance systems, long lasting batteries, and available computational power (both embedded and for image processing), allow to fly and to acquire data whatever the conditions of cloud cover. Furthermore, data acquisition is much more flexible than traditional satellite imagery: several flights can be performed in order to obtain the best conditions/acquisitions at a high spatiotemporal resolution. Moreover, the low-flying UAV yielding high picture resolution allows to generate high-resolution digital elevation models, and therefore, to measure accurately dynamics on the field with decimetre resolution in all three directions. Our objective is to show an experimental campaign of small UAV data acquisition in an arctic basin (Austre Lovén glacier, Svalbard, 78°N) separated by a few days. Knowing the changing conditions at this period, similar UAV flights have been reiterated in order to catch moraine dynamics. This allowed us to select two sets of images whose processing highlights and quantifies morphological changes into the moraine while a rain event occurred between two cold periods. © 2016 Informa UK Limited, trading as Taylor & Francis Group."
"7201951829;7005392086;57205479513;8719703500;10141883400;35550043200;8255698200;10140303900;7202944988;8516644900;6602872523;57194228711;6506886910;","Enhanced stratospheric water vapor over the summertime continental United States and the role of overshooting convection",2017,"10.5194/acp-17-6113-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019368901&doi=10.5194%2facp-17-6113-2017&partnerID=40&md5=2b1b3edaa52ae96b22966c4e22c146d3","The NASA ER-2 aircraft sampled the lower stratosphere over North America during the field mission for the NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS). This study reports observations of convectively influenced air parcels with enhanced water vapor in the overworld stratosphere over the summertime continental United States and investigates three case studies in detail. Water vapor mixing ratios greater than 10ppmv, which is much higher than the background 4 to 6ppmv of the overworld stratosphere, were measured by the JPL Laser Hygrometer (JLH Mark2) at altitudes between 16.0 and 17.5km (potential temperatures of approximately 380 to 410K). Overshooting cloud tops (OTs) are identified from a SEAC4RS OT detection product based on satellite infrared window channel brightness temperature gradients. Through trajectory analysis, we make the connection between these in situ water measurements and OT. Back trajectory analysis ties enhanced water to OT 1 to 7 days prior to the intercept by the aircraft. The trajectory paths are dominated by the North American monsoon (NAM) anticyclonic circulation. This connection suggests that ice is convectively transported to the overworld stratosphere in OT events and subsequently sublimated; such events may irreversibly enhance stratospheric water vapor in the summer over Mexico and the United States. A regional context is provided by water observations from the Aura Microwave Limb Sounder (MLS)."
"55977336000;7003663305;7410041005;35494005000;","Cloud vertical distribution from combined surface and space radar-lidar observations at two Arctic atmospheric observatories",2017,"10.5194/acp-17-5973-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019400120&doi=10.5194%2facp-17-5973-2017&partnerID=40&md5=4a69e40b32f57d76b82c6f928d60f7db","Detailed and accurate vertical distributions of cloud properties (such as cloud fraction, cloud phase, and cloud water content) and their changes are essential to accurately calculate the surface radiative flux and to depict the mean climate state. Surface and space-based active sensors including radar and lidar are ideal to provide this information because of their superior capability to detect clouds and retrieve cloud microphysical properties. In this study, we compare the annual cycles of cloud property vertical distributions from space-based active sensors and surface-based active sensors at two Arctic atmospheric observatories, Barrow and Eureka. Based on the comparisons, we identify the sensors' respective strengths and limitations, and develop a blended cloud property vertical distribution by combining both sets of observations. Results show that surface-based observations offer a more complete cloud property vertical distribution from the surface up to 11 km above mean sea level (a.m.s.l.) with limitations in the middle and high altitudes; the annual mean total cloud fraction from space-based observations shows 25-40 % fewer clouds below 0.5 km than from surface-based observations, and space-based observations also show much fewer ice clouds and mixed-phase clouds, and slightly more liquid clouds, from the surface to 1 km. In general, space-based observations show comparable cloud fractions between 1 and 2 km a.m.s.l., and larger cloud fractions above 2 km a.m.s.l. than from surface-based observations. A blended product combines the strengths of both products to provide a more reliable annual cycle of cloud property vertical distributions from the surface to 11 km a.m.s.l. This information can be valuable for deriving an accurate surface radiative budget in the Arctic and for cloud parameterization evaluation in weather and climate models. Cloud annual cycles show similar evolutions in total cloud fraction and ice cloud fraction, and lower liquid-containing cloud fraction at Eureka than at Barrow; the differences can be attributed to the generally colder and drier conditions at Eureka relative to Barrow. © 2017 Author(s)."
"25522765900;55878983900;7007172001;56122121300;57205479513;7201488063;14053547000;9036546900;35430463900;8791306500;7202489497;55995101900;35372923700;6506730508;7202400272;7006212411;34769585100;","The role of sulfur dioxide in stratospheric aerosol formation evaluated by using in situ measurements in the tropical lower stratosphere",2017,"10.1002/2017GL072754","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018258512&doi=10.1002%2f2017GL072754&partnerID=40&md5=30e8dfd04aab818da89e76e51f46ebeb","Stratospheric aerosols (SAs) are a variable component of the Earth's albedo that may be intentionally enhanced in the future to offset greenhouse gases (geoengineering). The role of tropospheric-sourced sulfur dioxide (SO2) in maintaining background SAs has been debated for decades without in situ measurements of SO2 at the tropical tropopause to inform this issue. Here we clarify the role of SO2 in maintaining SAs by using new in situ SO2 measurements to evaluate climate models and satellite retrievals. We then use the observed tropical tropopause SO2 mixing ratios to estimate the global flux of SO2 across the tropical tropopause. These analyses show that the tropopause background SO2 is about 5 times smaller than reported by the average satellite observations that have been used recently to test atmospheric models. This shifts the view of SO2 as a dominant source of SAs to a near-negligible one, possibly revealing a significant gap in the SA budget. ©2017. American Geophysical Union. All Rights Reserved."
"26434217100;54931083200;6602742025;22946301100;57193953105;24315205000;15069732800;6701363731;","A high resolution satellite view of surface solar radiation over the climatically sensitive region of Eastern Mediterranean",2017,"10.1016/j.atmosres.2016.12.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012285108&doi=10.1016%2fj.atmosres.2016.12.015&partnerID=40&md5=5b2b586b95f892a529d304d8e414b300","In this work, the spatiotemporal variability of surface solar radiation (SSR) is examined over the Eastern Mediterranean region for a 31-year period (1983–2013). The CM SAF SARAH (Satellite Application Facility on Climate Monitoring Solar surfAce RAdiation Heliosat) satellite-based product was found to be homogeneous (based on relative Standard Normal Homogeneity Tests — SNHTs, 95% confidence level) as compared to ground-based observations, and hence appropriate for climatological studies. Specifically, the dataset shows good agreement with monthly observations from five quality assured stations in the region with a mean bias of 7.1 W/m2 or 3.8% and a strong correlation. This high resolution (0.05° × 0.05°) product is capable of revealing various local features. Over land, the SSR levels are highly dependent on the topography, while over the sea, they exhibit a smooth latitudinal variability. SSR varies significantly over the region on a seasonal basis being three times higher in summer (309.6 ± 26.5 W/m2) than in winter (100.2 ± 31.4 W/m2). The CM SAF SARAH product was compared against three satellite-based and one reanalysis products. The satellite-based data from CERES (Cloud and the Earth's Radiant Energy System), GEWEX (Global Energy and Water Cycle Experiment) and ISCCP (International Satellite Cloud Climatology Project) underestimate SSR while the reanalysis data from the ERA-Interim overestimate SSR compared to CM SAF SARAH. Using a radiative transfer model and a set of ancillary data, these biases are attributed to the atmospheric parameters that drive the transmission of solar radiation in the atmosphere, namely, clouds, aerosols and water vapor. It is shown that the bias between CERES and CM SAF SARAH SSR can be explained through the cloud fractional cover and aerosol optical depth biases between these datasets. The CM SAF SARAH SSR trend was found to be positive (brightening) and statistically significant at the 95% confidence level (0.2 ± 0.05 W/m2/year or 0.1 ± 0.02%/year) being almost the same over land and sea. The CM SAF SARAH SSR trends are closer to the ground-based ones than the CERES, GEWEX, ISCCP and ERA-Interim trends. The use of an aerosol climatology for the production of CM SAF SARAH, that neglects the trends of aerosol loads, leads to an underestimation of the SSR trends. It is suggested here, that the inclusion of changes of the aerosol load and composition within CM SAF SARAH would allow for a more accurate reproduction of the SSR trends. © 2017 Elsevier B.V."
"57193058672;7202296460;57149502600;56472194800;56449803200;57193072863;7801521476;","Driver of the interannual variations of isotope in ice core from the middle of Tibetan Plateau",2017,"10.1016/j.atmosres.2017.01.006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010473686&doi=10.1016%2fj.atmosres.2017.01.006&partnerID=40&md5=5c3b6b8f91c6c0c9a8885143a2186cc2","Understanding the climatic significance of stable isotope in precipitation and ice cores on the Tibetan Plateau (TP) is of critical for the paleoclimate rebuilding. However, there is a gap between the seasonal control of precipitation and long-term isotope record from ice core. Here we present a well-dated ice core isotope record from the middle of the TP (mid-TP). Isotope variations in the past decades from this ice core show strong anti-phase relation with Southern Oscillation Index, confirming unequivocally that the large scale atmospheric circulation through the El Nino Southern Oscillation cycle, rather local climate parameters, controls the interannual signal in ice cores from the mid-TP. Results also show that the cloud top height in the northern Indian Ocean is in association with the interannual variations, confirming the same mechanism controlling the precipitation δ18O in southwest Asia and southeast Asia. The study will improve the understanding of the interannual change of Tibetan Plateau ice core isotope signal, and also the hydrological cycle in the southwest Asian region. © 2017 Elsevier B.V."
"22982270700;57190227631;56228672600;19638935200;56611366900;","Sensitivity study of cloud parameterizations with relative dispersion in CAM5.1: Impacts on aerosol indirect effects",2017,"10.5194/acp-17-5877-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019187622&doi=10.5194%2facp-17-5877-2017&partnerID=40&md5=14dff2fde9639f6adfab1a885dd57cb6","Aerosol-induced increase of relative dispersion of cloud droplet size distribution ϵ exerts a warming effect and partly offsets the cooling of aerosol indirect radiative forcing (AIF) associated with increased droplet concentration by increasing the cloud droplet effective radius (Re) and enhancing the cloud-to-rain autoconversion rate (Au) (labeled as the dispersion effect), which can help reconcile global climate models (GCMs) with the satellite observations. However, the total dispersion effects on both Re and Au are not fully considered in most GCMs, especially in different versions of the Community Atmospheric Model (CAM). In order to accurately evaluate the dispersion effect on AIF, the new complete cloud parameterizations of Re and Au explicitly accounting for ϵ are implemented into the CAM version 5.1 (CAM5.1), and a suite of sensitivity experiments is conducted with different representations of ϵ reported in the literature. It is shown that the shortwave cloud radiative forcing is much better simulated with the new cloud parameterizations as compared to the standard scheme in CAM5.1, whereas the influences on longwave cloud radiative forcing and surface precipitation are minimal. Additionally, consideration of the dispersion effect can significantly reduce the changes induced by anthropogenic aerosols in the cloud-top effective radius and the liquid water path, especially in the Northern Hemisphere. The corresponding AIF with the dispersion effect considered can also be reduced substantially by a range of 0.10 to 0.21 W m-2 at the global scale and by a much bigger margin of 0.25 to 0.39 W m-2 for the Northern Hemisphere in comparison with that of fixed relative dispersion, mainly dependent on the change of relative dispersion and droplet concentrations (Δϵ/ΔNc). © Author(s) 2017."
"35568218100;7004055120;7004250903;7006056992;13404087800;7003346742;7004208139;","Ensemble cloud-resolving modelling of a historic back-building mesoscale convective system over Liguria: The San Fruttuoso case of 1915",2017,"10.5194/cp-13-455-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019207161&doi=10.5194%2fcp-13-455-2017&partnerID=40&md5=1fd04c7bda1e9050200d57ec6c20454e","Highly localized and persistent back-building mesoscale convective systems represent one of the most dangerous flash-flood-producing storms in the north-western Mediterranean area. Substantial warming of the Mediterranean Sea in recent decades raises concerns over possible increases in frequency or intensity of these types of events as increased atmospheric temperatures generally support increases in water vapour content. However, analyses of the historical record do not provide a univocal answer, but these are likely affected by a lack of detailed observations for older events. In the present study, 20th Century Reanalysis Project initial and boundary condition data in ensemble mode are used to address the feasibility of performing cloud-resolving simulations with 1 km horizontal grid spacing of a historic extreme event that occurred over Liguria: The San Fruttuoso case of 1915. The proposed approach focuses on the ensemble Weather Research and Forecasting (WRF) model runs that show strong convergence over the Ligurian Sea (17 out of 56 members) as these runs are the ones most likely to best simulate the event. It is found that these WRF runs generally do show wind and precipitation fields that are consistent with the occurrence of highly localized and persistent back-building mesoscale convective systems, although precipitation peak amounts are underestimated. Systematic small north-westward position errors with regard to the heaviest rain and strongest convergence areas imply that the reanalysis members may not be adequately representing the amount of cool air over the Po Plain outflowing into the Ligurian Sea through the Apennines gap. Regarding the role of historical data sources, this study shows that in addition to reanalysis products, unconventional data, such as historical meteorological bulletins, newspapers, and even photographs, can be very valuable sources of knowledge in the reconstruction of past extreme events. © 2017 Author(s)."
"7201472576;36697726500;15069732800;56597778200;57193877432;9246517900;55541379500;35090272500;57194147922;24472110700;37111900500;6701530981;43461874800;57194145855;55749785900;57190384098;6701410329;","CLARA-A2: The second edition of the CM SAF cloud and radiation data record from 34 years of global AVHRR data",2017,"10.5194/acp-17-5809-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018896222&doi=10.5194%2facp-17-5809-2017&partnerID=40&md5=64ef5f77894c3b0cd275f1fd63ccb9af","The second edition of the satellite-derived climate data record CLARA (The CM SAF Cloud, Albedo And Surface Radiation dataset from AVHRR data-second edition denoted as CLARA-A2) is described. The data record covers the 34-year period from 1982 until 2015 and consists of cloud, surface albedo and surface radiation budget products derived from the AVHRR (Advanced Very High Resolution Radiometer) sensor carried by polar-orbiting, operational meteorological satellites. The data record is produced by the EUMETSAT Climate Monitoring Satellite Application Facility (CM SAF) project as part of the operational ground segment. Its upgraded content and methodology improvements since edition 1 are described in detail, as are some major validation results. Some of the main improvements to the data record come from a major effort in cleaning and homogenizing the basic AVHRR level-1 radiance record and a systematic use of CALIPSO-CALIOP cloud information for development and validation purposes. Examples of applications studying decadal changes in Arctic summer surface albedo and cloud conditions are provided. © 2017 The Author(s)."
"57189971829;56140087300;6602504147;12808146600;25723368400;7006204597;57132352100;57212446762;7404736154;57203015265;56613346300;7203040996;16444265000;35867336200;57194218182;7403735217;7004027519;","Observations of atmospheric chemical deposition to high Arctic snow",2017,"10.5194/acp-17-5775-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019245381&doi=10.5194%2facp-17-5775-2017&partnerID=40&md5=3cbbc727ddc96b752e927750c46ef634","Rapidly rising temperatures and loss of snow and ice cover have demonstrated the unique vulnerability of the high Arctic to climate change. There are major uncertainties in modelling the chemical depositional and scavenging processes of Arctic snow. To that end, fresh snow samples collected on average every 4 days at Alert, Nunavut, from September 2014 to June 2015 were analyzed for black carbon, major ions, and metals, and their concentrations and fluxes were reported. Comparison with simultaneous measurements of atmospheric aerosol mass loadings yields effective deposition velocities that encompass all processes by which the atmospheric species are transferred to the snow. It is inferred from these values that dry deposition is the dominant removal mechanism for several compounds over the winter while wet deposition increased in importance in the fall and spring, possibly due to enhanced scavenging by mixed-phase clouds. Black carbon aerosol was the least efficiently deposited species to the snow. © Author(s) 2017."
"56402112700;57188729460;9036557400;15725936000;57190583856;57196405343;","Downscaling GLDAS Soil moisture data in East Asia through fusion of Multi-Sensors by optimizing modified regression trees",2017,"10.3390/w9050332","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018406958&doi=10.3390%2fw9050332&partnerID=40&md5=e220ef42ff757b3206d798944a164af9","Soil moisture is a key part of Earth's climate systems, including agricultural and hydrological cycles. Soil moisture data from satellite and numerical models is typically provided at a global scale with coarse spatial resolution, which is not enough for local and regional applications. In this study, a soil moisture downscaling model was developed using satellite-derived variables targeting Global Land Data Assimilation System (GLDAS) soil moisture as a reference dataset in East Asia based on the optimization of a modified regression tree. A total of six variables, Advanced Microwave Scanning Radiometer 2 (AMSR2) and Advanced SCATterometer (ASCAT) soil moisture products, Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM), and MODerate resolution Imaging Spectroradiometer (MODIS) products, including Land Surface Temperature, Normalized Difference Vegetation Index, and land cover, were used as input variables. The optimization was conducted through a pruning approach for operational use, and finally 59 rules were extracted based on root mean square errors (RMSEs) and correlation coefficients (r). The developed downscaling model showed a good modeling performance (r = 0.79, RMSE = 0.056 m3·m−3, and slope = 0.74). The 1 km downscaled soil moisture showed similar time series patterns with both GLDAS and ground soil moisture and good correlation with ground soil moisture (average r = 0.47, average RMSD = 0.038 m3·m−3) at 14 ground stations. The spatial distribution of 1 km downscaled soil moisture reflected seasonal and regional characteristics well, although the model did not result in good performance over a few areas such as Southern China due to very high cloud cover rates. The results of this study are expected to be helpful in operational use to monitor soil moisture throughout East Asia since the downscaling model produces daily high resolution (1 km) real time soil moisture with a low computational demand. This study yielded a promising result to operationally produce daily high resolution soil moisture data from multiple satellite sources, although there are yet several limitations. In future research, more variables including Global Precipitation Measurement (GPM) precipitation, Soil Moisture Active Passive (SMAP) soil moisture, and other vegetation indices will be integrated to improve the performance of the proposed soil moisture downscaling model. © 2017 by the authors."
"57193238079;57212000722;56405496200;57205872550;","Adding value to INSAT-3D sea surface temperature fields using MODIS data over the tropical Indian Ocean",2017,"10.1080/2150704X.2017.1280201","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012022720&doi=10.1080%2f2150704X.2017.1280201&partnerID=40&md5=e8046e35f7b7feb85368962d33613749","Accurate estimates of sea surface temperature (SST) are crucial for climate studies, numerical weather prediction and air–sea interactions. Following the launch of India’s advanced geostationary satellite–INSAT-3D with two thermal infrared split window channels in 2013, it is now possible to monitor land and ocean surfaces more reliably at higher spatiotemporal scale. In this article, an attempt has been made to develop a more accurate infrared-based cloud-free SST estimates over the tropical Indian Ocean by the synergistic use of geostationary INSAT-3D and polar-orbiting Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) satellite measurements through a successive correction method. This method is applied primarily for the month of May 2015 at coarser spatial resolution and at a daily scale. Results are compared independently with multi-satellite SST estimates and also against in situ observations such as Argo floats and buoys. The merged SST product shows noticeable improvement over INSAT-3D-based estimates alone. Comparison of the merged SST product with Argo observations shows that the root mean square difference (RMSD) has been improved from 1.23 to 0.79 K, and bias and correlation are also significantly improved. Overall results indicate that the synergistic use of INSAT-3D and MODIS satellite observations has potential for more accurate SST estimation over the tropical Indian Ocean at finer temporal resolution and larger spatial coverage for several near-real time meteorological and oceanographic applications. © 2017 Informa UK Limited, trading as Taylor & Francis Group."
"56001571800;22133985200;25923565300;7201423091;","Determining stages of cirrus evolution: A cloud classification scheme",2017,"10.5194/amt-10-1653-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018743269&doi=10.5194%2famt-10-1653-2017&partnerID=40&md5=45d80f5387ba9db27359e0c41f7e5439","Cirrus clouds impose high uncertainties on climate prediction, as knowledge on important processes is still incomplete. For instance it remains unclear how cloud microphysical and radiative properties change as the cirrus evolves. Recent studies classify cirrus clouds into categories including in situ, orographic, convective and liquid origin clouds and investigate their specific impact. Following this line, we present a novel scheme for the classification of cirrus clouds that addresses the need to determine specific stages of cirrus evolution. Our classification scheme is based on airborne Differential Absorption and High Spectral Resolution Lidar measurements of atmospheric water vapor, aerosol depolarization, and backscatter, together with model temperature fields and simplified parameterizations of freezing onset conditions. It identifies regions of supersaturation with respect to ice (ice-supersaturated regions, ISSRs), heterogeneous and homogeneous nucleation, depositional growth, and ice sublimation and sedimentation with high spatial resolution. Thus, all relevant stages of cirrus evolution can be classified and characterized. In a case study of a gravity lee-wave-influenced cirrus cloud, encountered during the ML-CIRRUS flight campaign, the applicability of our classification is demonstrated. Revealing the structure of cirrus clouds, this valuable tool might help to examine the influence of evolution stages on the cloud's net radiative effect and to investigate the specific variability of optical and microphysical cloud properties in upcoming research. © Author(s) 2017."
"55247565600;55969140000;55948466000;14625770800;","Ground-Based Cloud Detection Using Graph Model Built Upon Superpixels",2017,"10.1109/LGRS.2017.2676007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016121549&doi=10.1109%2fLGRS.2017.2676007&partnerID=40&md5=54088ad018ce19e21cf8a44fb8f6b93e","Cloud detection plays an important role in climate models, climate predictions, and meteorological services. Although researchers have given increasing efforts on cloud detection, the performance is still unsatisfactory due to the diverse nature of clouds. Considering the fact that one source of information (color or texture) is not enough to segment cloud from clear sky, in this letter, we propose a novel ground-based cloud detection method using graph model (GM) built upon superpixels to integrate multiple sources of information. First, we use the superpixel segmentation to divide the image into a series of subregions according to the color similarity and spatial continuity. Next, adjacent superpixels are merged according to their similarity of extracted features. Finally, we build a GM on the merged superpixels by considering each superpixel as a node and adding edges between neighboring ones. The unary cost is set according to the classification score of Random Forests, while pairwise cost reflects the penalties for color and texture discontinuity between neighboring components. The final segmentation could be acquired by minimizing the cost function. Moreover, the algorithm is computationally efficient as we use the superpixels rather than raw pixels as computation units. Experimental results demonstrate the effectiveness and efficiency of the proposed method for cloud detection. © 2017 IEEE."
"56457851700;16024614000;7202145115;24722339600;","The change in low cloud cover in a warmed climate inferred from AIRS, MODIS, and ERA-interim",2017,"10.1175/JCLI-D-15-0734.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018978599&doi=10.1175%2fJCLI-D-15-0734.1&partnerID=40&md5=0858acdbcb6b7121a71ff2fea8166b81","Decreases in subtropical low cloud cover (LCC) occur in climate model simulations of global warming. In this study 8-day-averaged observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Atmospheric Infrared Sounder (AIRS) spanning 2002-14 are combined with European Centre for Medium-Range Weather Forecasts (ECMWF) interim reanalysis to compute the dependence of the observed variability of LCC on various predictor variables. Large-scale thermodynamic and dynamic predictors of LCC are selected based on insight from large-eddy simulations (LESs) and observational analysis. It is found that increased estimated inversion strength (EIS) is associated with increased LCC. Drying of the free troposphere is associated with decreased LCC. Decreased LCC accompanies subsidence in regions of relatively low EIS; the opposite is found in regions of high EIS. Finally, it is found that increasing sea surface temperature (SST) leads to a decrease in LCC. These results are in keeping with previous studies of monthly and annual data. Based upon the observed response of LCC to natural variability of the control parameters, the change in LCC is estimated for an idealized warming scenario where SST increases by 1 K and EIS increases by 0.2 K. For this change in EIS and SST the LCC is inferred to decrease by 0.5%-2.7% when the regression models are trained on data observed between 40°S and 40°N and by 1.1%-1.4% when trained on data from trade cumulus-dominated regions. When the data used to train the regression model are restricted to stratocumulus-dominated regions the change in LCC is highly uncertain and varies between -1.6% and +1.4%, depending on the stratocumulus-dominated region used to train the regression model. © 2017 American Meteorological Society."
"57218148217;55745955800;8859530100;56950761500;","Cloud transitions: comparison of temporal variation in the southeastern Pacific with the spatial variation in the northeastern Pacific at low latitudes",2017,"10.1002/joc.4889","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991383481&doi=10.1002%2fjoc.4889&partnerID=40&md5=a85a1c689f82e9015399dd92254d2ecc","The seasonal variation of clouds in the southeastern equatorial Pacific (SEP) is analysed and compared with the spatial variation of clouds in the northeastern Pacific along the Global Energy and Water Cycle Experiment Cloud System Study/Working Group on Numerical Experimentation (GCSS/WGNE) Pacific Cross-Section Intercomparison (GPCI) transect. A ‘seasonal cloud transition’ – from stratocumulus to shallow cumulus and eventually to deep convection – is found in the SEP from September to April, which is similar to the spatial cloud transition along the GPCI transect from the California coast to the equator. It is shown that this seasonal cloud transition in the SEP is associated with increasing sea surface temperature (SST), decreasing lower tropospheric stability and large-scale subsidence, which are all similar to the spatial variation of these fields along the GPCI transect. Difference is found that the SEP cloud transition is associated with decreasing surface wind speed and surface latent heat flux, weaker larger-scale upward motion and convective instability, which lead to less deepening of the low clouds and less frequent deep convection than those in the GPCI transect. The seasonal cloud transition in the SEP provides a test for climate models to simulate the relationships between clouds and large-scale atmospheric fields in a region that features a spurious double inter-tropical convergence zone (ITCZ) in most models. © 2016 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"56004685100;6603156461;7005809959;","Toward reduced representation of mixing state for simulating aerosol effects on climate",2017,"10.1175/BAMS-D-16-0028.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019859244&doi=10.1175%2fBAMS-D-16-0028.1&partnerID=40&md5=26e8a66881de55f0c22a3f9196d1b17b","A benchmarking framework reveals the extent to which the chemical composition of particles must be resolved to accurately represent aerosol radiative effects and cloud interactions. © 2017 American Meteorological Society."
"57189372185;7004864963;7102866124;7003461830;8691681600;57204253860;36076994600;25924706200;55683878900;54781196300;24481185800;57194398717;36627462600;56429387500;8312732800;9846347800;57194386008;57203048897;35461763400;7006790175;7004938676;7006643234;7006303509;15080710300;7004346367;8511991900;57194390231;7005206400;6508030754;8658386900;57194382517;57194396943;7102062952;6603569074;57198616562;57203776263;57194398699;47761279900;24491934500;57194399145;7005838371;12803904100;57194381419;57213437264;13408773700;6507506955;55348930900;8871497700;57194381041;55942083800;7102830450;7102654014;57194388748;57201177267;7410177774;35276210200;26434039800;57190209035;","The green ocean amazon experiment (GOAMAZON2014/5) observes pollution affecting gases, aerosols, clouds, and rainfall over the rain forest",2017,"10.1175/BAMS-D-15-00221.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019945583&doi=10.1175%2fBAMS-D-15-00221.1&partnerID=40&md5=883a3d65ccdba5e7acfb224586d7897b","The susceptibility of air quality, weather, terrestrial ecosystems, and climate to human activities was investigated in a tropical environment. © 2017 American Meteorological Society."
"8576809500;57188844947;55259753300;7202674384;54418139400;6602189006;6603814881;","The role of epiphytic bryophytes in interception, storage, and the regulated release of atmospheric moisture in a tropical montane cloud forest",2017,"10.1016/j.jhydrol.2017.03.043","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016490962&doi=10.1016%2fj.jhydrol.2017.03.043&partnerID=40&md5=9e9288a874194d4c566cdd708c2a01f8","Epiphytes in tropical montane cloud forests (TMCF) intercept atmospheric water and, as a result, form a vital part of the hydrological cycle of this ecosystem. Our study investigates the role of bryophytes in such systems on La Réunion Island (Mascarenes). To better understand ecohydrological functioning of the forest, we investigated cloud water interception (CWI) by two locally abundant liverwort species (Bazzania decrescens and Mastigophora diclados) using a novel lysimetric approach. We also evaluated biomass and water storage capacity of our study species, as well as of the entire bryophyte community in our plots, which we extrapolated to the forest community level. Both study species exhibited excellent abilities to intercept and store cloud water, and showed distinct diurnal variation in this ability according to varying climatic conditions. The two liverwort species’ response to climatic conditions differed dramatically from one another, with B. decrescens storing double the mean and maximum litres of water per hectare despite having less than half the abundance of M. diclados. Despite its lower water storage capacity, M. diclados had a greater ability to intercept atmospheric moisture than B. decrescens. The differences in CWI were attributed to differences in plant structure of these two species, which explains their microhabitat requirements in this system. Our two species in this system were estimated to store 34,569 l.ha−1 of water, the equivalent of 3.46 mm of rainfall. The abundance of our study species combined with their atmospheric water interception, storage, and regulated release ability make both species ecologically important in the forest's microhydrological cycle. For the first time these data allow us to better understand the role of these plants in the microhydrological cycle of tropical montane cloud forests and to determine whether the diversity and functioning of these and similar systems will be at risk from predicted cloud layer/coverage lifting. © 2017 Elsevier B.V."
"6701438752;","Fitting rainfall interception models to forest ecosystems of Mexico",2017,"10.1016/j.jhydrol.2017.03.025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015755583&doi=10.1016%2fj.jhydrol.2017.03.025&partnerID=40&md5=f03825aa36c4c2f3dad94ec58451b108","Models that accurately predict forest interception are essential both for water balance studies and for assessing watershed responses to changes in land use and the long-term climate variability. This paper compares the performance of four rainfall interception models—the sparse Gash (1995), Rutter et al. (1975), Liu (1997) and two new models (NvMxa and NvMxb)—using data from four spatially extensive, structurally diverse forest ecosystems in Mexico. Ninety-eight case studies measuring interception in tropical dry (25), arid/semi-arid (29), temperate (26), and tropical montane cloud forests (18) were compiled and analyzed. Coefficients derived from raw data or published statistical relationships were used as model input to evaluate multi-storm forest interception at the case study scale. On average empirical data showed that, tropical montane cloud, temperate, arid/semi-arid and tropical dry forests intercepted 14%, 18%, 22% and 26% of total precipitation, respectively. The models performed well in predicting interception, with mean deviations between measured and modeled interception as a function of total precipitation (ME) generally <5.8% and Nash-Sutcliffe efficiency E estimators >0.66. Model fitting precision was dependent on the forest ecosystem. Arid/semi-arid forests exhibited the smallest, while tropical montane cloud forest displayed the largest ME deviations. Improved agreement between measured and modeled data requires modification of in-storm evaporation rate in the Liu; the canopy storage in the sparse Gash model; and the throughfall coefficient in the Rutter and the NvMx models. This research concludes on recommending the wide application of rainfall interception models with some caution as they provide mixed results. The extensive forest interception data source, the fitting and testing of four models, the introduction of a new model, and the availability of coefficient values for all four forest ecosystems are an important source of information and a benchmark for future investigations in this area of hydrology. © 2017 Elsevier B.V."
"7006095466;7409792174;6506848305;","Simulation, modeling, and dynamically based parameterization of organized tropical convection for global climate models",2017,"10.1175/JAS-D-16-0166.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018379930&doi=10.1175%2fJAS-D-16-0166.1&partnerID=40&md5=c033d7f278553cbda70a652788c128b7","A new approach for treating organized convection in global climate models (GCMs) referred to as multiscale coherent structure parameterization (MCSP) introduces physical and dynamical effects of organized convection that are missing from contemporary parameterizations. The effects of vertical shear are approximated by a nonlinear slantwise overturning model based on Lagrangian conservation principles. Simulation of the April 2009 Madden-Julian oscillation event during the Year of Tropical Convection (YOTC) over the Indian Ocean using the Weather Research and Forecasting (WRF) Model at 1.3-km grid spacing identifies self-similar properties for squall lines, MCSs, and superclusters embedded in equatorial waves. The slantwise overturning model approximates this observed self-similarity. The large-scale effects of MCSP are examined in two categories of GCM. First, large-scale convective systems simulated in an aquaplanet model are approximated by slantwise overturning with attention to convective momentum transport. Second, MCSP is utilized in the Community Atmosphere Model, version 5.5 (CAM5.5), as tendency equations for second-baroclinic heating and convective momentum transport. The difference between MCSP and CAM5.5 is a direct measure of the global effects of organized convection. Consistent with TRMM measurements, the MCSP generates large-scale precipitation patterns in the tropical warm pool and the adjoining locale; improves precipitation in the intertropical convergence zone (ITCZ), South Pacific convergence zone (SPCZ), and Maritime Continent regions; and affects tropical wave modes. In conclusion, the treatment of organized convection by MCSP is salient for the next generation of GCMs. © 2017 American Meteorological Society."
"35090272500;55613774900;56702309200;15069732800;6701410329;","A satellite-based sunshine duration climate data record for Europe and Africa",2017,"10.3390/rs9050429","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019924377&doi=10.3390%2frs9050429&partnerID=40&md5=f902bec46b160a0f45a88cbfedb0ed2b","Besides 2 m temperature and precipitation, sunshine duration is one of the most important and commonly used parameter in climatology, with measured time series of partly more than 100 years in length. EUMETSAT's Satellite Application Facility on Climate Monitoring (CM SAF) presents a climate data record for daily and monthly sunshine duration (SDU) for Europe and Africa. Basis for the advanced retrieval is a highly resolved satellite product of the direct solar radiation from measurements by Meteosat satellites 2 to 10. The data record covers the time period 1983 to 2015 with a spatial resolution of 0.05° × 0.05°. The comparison against ground-based data shows high agreement but also some regional differences. Sunshine duration is overestimated by the satellite-based data in many regions, compared to surface data. InWest and Central Africa, low clouds seem to be the reason for a stronger overestimation of sunshine duration in this region (up to 20% for monthly sums). For most stations, the overestimation is low, with a bias below 7.5 h for monthly sums and below 0.4 h for daily sums. A high correlation of 0.91 for daily SDU and 0.96 for monthly SDU also proved the high agreement with station data. As SDU is based on a stable and homogeneous climate data record of more than 30 years length, it is highly suitable for climate applications, such as trend estimates. © 2017 by the authors."
"56533635500;56249280600;57203321797;56533081000;37117231000;","Potential feedback between aerosols and meteorological conditions in a heavy pollution event over the Tibetan Plateau and Indo-Gangetic Plain",2017,"10.1007/s00382-016-3240-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975318521&doi=10.1007%2fs00382-016-3240-2&partnerID=40&md5=adf1641a87d8813022d9280c39036fd1","A regional climate model, WRF-Chem, was used to investigate the feedback between aerosols and meteorological conditions in the planetary boundary layer (PBL) over the Tibetan Plateau (TP) and Indo-Gangetic Plain (IGP). The numerical experiments (15-km horizontal resolution) with and without the aerosol effects are driven by reanalysis of data for 1–31 March 2009, when a heavy pollution event (13–19 March) occurred. The results showed that the model captured the spatial and temporal meteorological conditions and aerosol optical characteristics during the heavy pollution days. Aerosols induced cooling at the surface and warming in the middle troposphere due to their radiative effects, and resulted in a more stable PBL over the IGP. Aerosol-induced 2-m relative humidity (RH) was increased. The stable PBL likely led to the surface PM2.5 concentration increase of up to 21 μg m−3 (15 %) over the IGP. For the TP, the atmospheric profile did not drastically change due to fewer radiative effects of aerosols in the PBL compared with those over the IGP. The aerosol-induced RH decreased due to cloud albedo and cloud lifetime effect, and led to a reduction in surface PM2.5 concentration of up to 17 μg m−3 (13 %). These results suggest a negative and positive feedback over the TP and IGP, respectively, between aerosol concentrations and changes of aerosol-induced meteorological conditions. Similar positive feedbacks have been observed in other heavily polluted regions (e.g., the North China Plain). The results have implications for the study of air pollution on weather and environment over the TP and IGP. © 2016, Springer-Verlag Berlin Heidelberg."
"6602702069;6506104366;55315290600;6603926727;7006065540;7005618829;","Intra-seasonal and Inter-annual variability of Bowen Ratio over rain-shadow region of North peninsular India",2017,"10.1007/s00704-016-1745-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957572411&doi=10.1007%2fs00704-016-1745-6&partnerID=40&md5=2e8350b3fb2230fcdc6a56f050e0cca0","Intra-seasonal and inter-annual variability of Bowen Ratio (BR) have been studied over the rain-shadow region of north peninsular India during summer monsoon season. Daily grid point data of latent heat flux (LHF), sensible heat flux (SHF) from NCEP/NCAR Reanalysis for the period 1970–2014 have been used to compute daily area-mean BR. Daily grid point rainfall data at a resolution of 0.25° × 0.25° from APHRODITE’s Water Resources for the available period 1970–2007 have been used to study the association between rainfall and BR. The study revealed that BR rapidly decreases from 4.1 to 0.29 in the month of June and then remains nearly constant at the same value (≤0.1) in the rest of the season. High values of BR in the first half of June are indicative of intense thermals and convective clouds with higher bases. Low values of BR from July to September period are indicative of weak thermals and convective clouds with lower bases. Intra-seasonal and inter-annual variability of BR is found to be inversely related to precipitation over the region. BR analysis indicates that the land surface characteristics of the study region during July–September are similar to that over oceanic regions as far as intensity of thermals and associated cloud microphysical properties are concerned. Similar variation of BR is found in El Nino and La Nina years. During June, an increasing trend is observed in SHF and BR and decreasing trend in LHF from 1976 to 2014. Increasing trend in the SHF is statistically significant. © 2016, Springer-Verlag Wien."
"36497832500;7404433688;57206252295;57194116660;","Radiative forcing of the tropical thick anvil evaluated by combining TRMM with atmospheric radiative transfer model",2017,"10.1002/asl.746","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018771712&doi=10.1002%2fasl.746&partnerID=40&md5=a814480afd9fffca46244490516eb6d5","The presences of anvil clouds significantly affect the tropical mean radiation budget and increase the uncertainty of climate model simulations. In this study, the climatological mean distributions of thick anvil parameters, such as top, bottom, occurrence, cloud effective radius (CER) and cloud optical depth (COD) in the tropics (20°S–20°N) are investigated by Tropical Rainfall Measuring Mission's (TRMM) precipitation radar (PR) and visible and infrared scanner (VIRS) from 1998 to 2007. The thick anvil radiative forcing at shortwave (0.2 ∼ 4 µm) and longwave (4 ∼ 50 µm) length, i.e. Shortwave radiative forcing (SRF) and Longwave radiative forcing (LRF) and their net effects at different altitudes are simulated with Santa Barbara DISORT Atmospheric Radiative Transfer Model (SBDART). The results show that thick anvils present higher top/bottom, smaller CER, and thicker COD over land than those over ocean. At the top of atmosphere (TOA), net radiative effects of thick anvils are positive warming, which means the earth-atmosphere system obtains energy forced by thick anvils. At earth surface, net radiative effects of thick anvils are positive warming at land surface and negative cooling at ocean surface, respectively. In general, anvil SRF, LRF and net effects vary with different geographical locations and also present large land–ocean differences in the tropics, due to different anvil properties forced by the surface heating and topography. All spatial patterns of stronger anvil SRF, LRF and net effects are well matched with the places where exist higher fractions of anvils, such as Asian monsoon zone, the Intertropical Convergence Zone (ITCZ), the South Pacific Convergence Zone (SPCZ), tropical Africa, Mid-America and South America. In addition, the present work provides an evidence that it is an effective approach to calculate quantitatively the grid-cell SRF and LRF of cloud at a large scale by using the SBDART model with inputs from satellite observations. © 2017 The Authors. Atmospheric Science Letters published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"56135196400;7403872687;6507378331;7005052907;7401526171;","Precipitation identification with bispectral satellite information using deep learning approaches",2017,"10.1175/JHM-D-16-0176.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019030320&doi=10.1175%2fJHM-D-16-0176.1&partnerID=40&md5=558e83622cfe32be2e28350847eda415","In the development of a satellite-based precipitation product, two important aspects are sufficient precipitation information in the satellite-input data and proper methodologies, which are used to extract such information and connect it to precipitation estimates. In this study, the effectiveness of the state-of-the-art deep learning (DL) approaches to extract useful features from bispectral satellite information, infrared (IR), and water vapor (WV) channels, and to produce rain/no-rain (R/NR) detection is explored. To verify the methodologies, two models are designed and evaluated: the first model, referred to as the DL-IR only method, applies deep learning approaches to the IR data only; the second model, referred to as the DL-IR+WV method, incorporates WV data to further improve the precipitation identification performance. The radar stage IV data are the reference data used as ground observation. The operational product, Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks-Cloud Classification System (PERSIANN-CCS), serves as a baseline model with which to compare the performances. The experiments show significant improvement for both models in R/NR detection. The overall performance gains in the critical success index (CSI) are 21.60% and 43.66% over the verification periods for the DL-IR only model and the DL-IR+WV model compared to PERSIANN-CCS, respectively. In particular, the performance gains in CSI are as high as 46.51% and 94.57% for the models for the winter season. Moreover, specific case studies show that the deep learning techniques and the WV channel information effectively help recover a large number of missing precipitation pixels under warm clouds while reducing false alarms under cold clouds. © 2017 American Meteorological Society."
"57193572701;57193578865;","Multispectral and Microwave Remote Sensing Models to Survey Soil Moisture and Salinity",2017,"10.1002/ldr.2661","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015100361&doi=10.1002%2fldr.2661&partnerID=40&md5=949d1fa12872fc915851cb48fac02210","Soil moisture stress and salinity are considered as a major form of land degradation in rain-fed agricultural regions. The study has been carried out for four distinct periods such as 2001, 2005, 2010, and 2015 that was selected according to the climatic variations that occurred more than a decade. The multispectral remote sensing-based empirical models were employed on Enhanced Thematic Mapper Plus and Operational Land Imager imageries to estimate the rate of soil moisture stress and salinity from 2001–2015. The rate of soil moisture stress has been magnified to 143%, and salinity was increased by 70% particularly from 2005–2010 when the drought period occurred. The reliability of identifying the saline-affected soils from the multispectral remote sensing models was significantly affected (R2 = 0.39) because of the extensive distribution of Nerium oleander plants and water logging state in the study region. The modified microwave water cloud model revealed the three-layer information such as N. oleander, soil, and vegetation such that an imaginary part of the dielectric constant derived from simplified Hallikainen empirical model has got good correlation (R2 = 0.73) with ground electrical conductivity measurements. Copyright © 2016 John Wiley &amp; Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd."
"7403191133;","Seasonal variability in size-segregated airborne bacterial particles and their characterization at different source-sites",2017,"10.1007/s11356-017-8705-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017137727&doi=10.1007%2fs11356-017-8705-2&partnerID=40&md5=ce2413aa5bf2393f9ae8bbaf4ce9eed3","Size-segregated aerosol samplings were carried out near the potential sources of airborne biological particles i.e. at a landfill site, an agricultural field and a road side restaurant-cluster site in winter, spring and summer seasons during 2013–2015 in New Delhi. The culturable airborne bacterial (CAB) concentrations showed significant seasonal variation from higher to moderate in spring and winter seasons and lowest during summer. Highest CAB concentrations were observed at the Okhla landfill site followed by restaurant-cluster area and agriculture site. The CAB particles showed bimodal size distribution, abundant in the size ranges of 1.1–2.1, 2.1–3.3 and 4.7–5.8 μm. However, substantial concentrations were also observed in the size bins of 0.43–0.65 and <0.43 μm, which are important for cloud condensation nuclei (CCN) activity of aerosols in addition to their adverse health effects. In spring, bacterial particles were also maximized in size ranges between 5.8 and >9.0 μm. Fine mode proportions of CAB were found to be higher in winter than other two seasons. Bacterial identification was done by 16s rDNA sequencing, and most abundant identified strains were Bacillus cereus (16%), Bacillus licheniformis (11%), Bacillus thuringiensis (9%), Micrococcus sp. (7%) and Acinetobacter sp. (9%). © 2017, Springer-Verlag Berlin Heidelberg."
"55957596200;57094306300;55742038700;36061813500;55653363200;","Enhanced water use efficiency in global terrestrial ecosystems under increasing aerosol loadings",2017,"10.1016/j.agrformet.2017.02.002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011818916&doi=10.1016%2fj.agrformet.2017.02.002&partnerID=40&md5=44d180390101d04d4e28131f9d5d57e7","Aerosols play a crucial role in the climate system, affecting incoming radiation and cloud formation. Based on a modelling framework that couples ecosystem processes with the atmospheric transfer of radiation, we analyze the effect of aerosols on surface incoming radiation, gross primary productivity (GPP), water losses from ecosystems through evapotranspiration (ET) and ecosystem water use efficiency (WUE, defined as GPP/ET) for 2003–2010 and validate them at global FLUXNET sites. The total diffuse radiation increases under relatively low or intermediate aerosol loadings, but decreases under more polluted conditions. We find that aerosol-induced changes in GPP depend on leaf area index, aerosol loading and cloudiness. Specifically, low and moderate aerosol loadings cause increases in GPP for all plant types, while heavy aerosol loadings result in enhancement (decrease) in GPP for dense (sparse) vegetation. On the other hand, ET is mainly negatively affected by aerosol loadings due to the reduction in total incoming radiation. Finally, WUE shows a consistent rise in all plant types under increasing aerosol loadings. Overall, the simulated daily WUE compares well with observations at 43 eddy-covariance tower sites (R2 = 0.84 and RMSE = 0.01 g C (kg H2O)−1) with better performance at forest sites. In addition to the increasing portions of diffuse light, the rise in WUE is also favored by the reduction in radiation- and heat-stress caused by the aerosols, especially for wet and hot climates. © 2017 Elsevier B.V."
"9740039900;7005246332;6507675882;6603385683;57193748064;56243460400;15767163400;","Evaluation of MODIS albedo product over ice caps in Iceland and impact of volcanic eruptions on their albedo",2017,"10.3390/rs9050399","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019844356&doi=10.3390%2frs9050399&partnerID=40&md5=0be1af1c0ee64b4326b1ea4d0b85edb2","Albedo is a key variable in the response of glaciers to climate. In Iceland, large albedo variations of the ice caps may be caused by the deposition of volcanic ash (tephra). Sparse in situ measurements are insufficient to characterize the spatial variation of albedo over the ice caps due to their large size. Here we evaluated the latest MCD43 MODIS albedo product (collection 6) to monitor albedo changes over the Icelandic ice caps using albedo measurements from ten automatic weather stations on Vatnajökull and Langjökull. Furthermore, we examined the influence of the albedo variability within MODIS pixels by comparing the results with a collection of Landsat scenes. The results indicate a good ability of the MODIS product to characterize the seasonal and interannual albedo changes with correlation coefficients ranging from 0.47 to 0.90 (median 0.84) and small biases ranging from -0.07 to 0.09. The root-mean square errors (RMSE) ranging from 0.08 to 0.21, are larger than that from previous studies, but we did not discard the retrievals flagged as bad quality to maximize the amount of observations given the frequent cloud obstruction in Iceland. We found a positive but non-significant relationship between the RMSE and the subpixel variability as indicated by the standard deviation of the Landsat albedo within a MODIS pixel (R = 0.48). The summer albedo maps and time series computed from the MODIS product show that the albedo decreased significantly after the 2010 Eyjafjallajökull and 2011 Grímsvötn eruptions on all the main ice caps except the northernmost Drangajökull. A strong reduction of the summer albedo by up to 0.6 is observed over large regions of the accumulation areas. These data can be assimilated in an energy and mass balance model to better understand the relative influence of the volcanic and climate forcing to the ongoing mass losses of Icelandic ice caps. © 2017 by the authors."
"6701751765;57192201374;34969720500;6603150451;26323026900;7005574185;","A post-new horizons global climate model of Pluto including the N2, CH4 and CO cycles",2017,"10.1016/j.icarus.2016.11.038","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008395735&doi=10.1016%2fj.icarus.2016.11.038&partnerID=40&md5=c5bdfa12a3a1cd646314b9bf2b7f8e4e","We have built a new 3D Global Climate Model (GCM) to simulate Pluto as observed by New Horizons in 2015. All key processes are parametrized on the basis of theoretical equations, including atmospheric dynamics and transport, turbulence, radiative transfer, molecular conduction, as well as phases changes for N2, CH2 and CO. Pluto's climate and ice cycles are found to be very sensitive to model parameters and initial states. Nevertheless, a reference simulation is designed by running a fast, reduced version of the GCM with simplified atmospheric transport for 40,000 Earth years to initialize the surface ice distribution and sub-surface temperatures, from which a 28-Earth-year full GCM simulation is performed. Assuming a topographic depression in a Sputnik-planum (SP)-like crater on the anti-Charon hemisphere, a realistic Pluto is obtained, with most N2 and CO ices accumulated in the crater, methane frost covering both hemispheres except for the equatorial regions, and a surface pressure near 1.1 Pa in 2015 with an increase between 1988 and 2015, as reported from stellar occultations. Temperature profiles are in qualitative agreement with the observations. In particular, a cold atmospheric layer is obtained in the lowest kilometers above Sputnik Planum, as observed by New Horizons's REX experiment. It is shown to result from the combined effect of the topographic depression and N2 daytime sublimation. In the reference simulation with surface N2 ice exclusively present in Sputnik Planum, the global circulation is only forced by radiative heating gradients and remains relatively weak. Surface winds are locally induced by topography slopes and by N2 condensation and sublimation around Sputnik Planum. However, the circulation can be more intense depending on the exact distribution of surface N2 frost. This is illustrated in an alternative simulation with N2 condensing in the South Polar regions and N2 frost covering latitudes between 35°N and 48°N. A global condensation flow is then created, inducing strong surface winds everywhere, a prograde jet in the southern high latitudes, and an equatorial superrotation likely forced by barotropic instabilities in the southern jet. Using realistic parameters, the GCM predict atmospheric concentrations of CO and CH4 in good agreement with the observations. N2 and CO do not condense in the atmosphere, but CH4 ice clouds can form during daytime at low altitude near the regions covered by N2 ice (assuming that nucleation is efficient enough). This global climate model can be used to study many aspects of the Pluto environment. For instance, organic hazes are included in the GCM and analysed in a companion paper (Bertrand and Forget, Icarus, this issue). © 2016 Elsevier Inc."
"24446327700;","An energy balance perspective on regional CO2-induced temperature changes in CMIP5 models",2017,"10.1007/s00382-016-3277-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982946466&doi=10.1007%2fs00382-016-3277-2&partnerID=40&md5=f62cb4841ec445581b8b92d23d7a913e","An energy balance decomposition of temperature changes is conducted for idealized transient CO2-only simulations in the fifth phase of the Coupled Model Intercomparison Project. The multimodel global mean warming is dominated by enhanced clear-sky greenhouse effect due to increased CO2 and water vapour, but other components of the energy balance substantially modify the geographical and seasonal patterns of the change. Changes in the net surface energy flux are important over the oceans, being especially crucial for the muted warming over the northern North Atlantic and for the seasonal cycle of warming over the Arctic Ocean. Changes in atmospheric energy flux convergence tend to smooth the gradients of temperature change and reduce its land-sea contrast, but they also amplify the seasonal cycle of warming in northern North America and Eurasia. The three most important terms for intermodel differences in warming are the changes in the clear-sky greenhouse effect, clouds, and the net surface energy flux, making the largest contribution to the standard deviation of annual mean temperature change in 34, 29 and 20 % of the world, respectively. Changes in atmospheric energy flux convergence mostly damp intermodel variations of temperature change especially over the oceans. However, the opposite is true for example in Greenland and Antarctica, where the warming appears to be substantially controlled by heat transport from the surrounding sea areas. © 2016, Springer-Verlag Berlin Heidelberg."
"47761806800;14020325100;57212280726;","Convective-scale data assimilation for the weather research and forecasting model using the local particle filter",2017,"10.1175/MWR-D-16-0298.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018360643&doi=10.1175%2fMWR-D-16-0298.1&partnerID=40&md5=771e28823eec998fbbb517c49f0db651","Particle filters (PFs) are Monte Carlo data assimilation techniques that operate with no parametric assumptions for prior and posterior errors. A data assimilation method introduced recently, called the local PF, approximates the PF solution within neighborhoods of observations, thus allowing for its use in high-dimensional systems. The current study explores the potential of the local PF for atmospheric data assimilation through cloud-permitting numerical experiments performed for an idealized squall line. Using only 100 ensemble members, experiments using the local PF to assimilate simulated radar measurements demonstrate that the method provides accurate analyses at a cost comparable to ensemble filters currently used in weather models. Comparisons between the local PF and an ensemble Kalman filter demonstrate benefits of the local PF for producing probabilistic analyses of non-Gaussian variables, such as hydrometeor mixing ratios. The local PF also provides more accurate forecasts than the ensemble Kalman filter, despite yielding higher posterior root-mean-square errors. A major advantage of the local PF comes from its ability to produce more physically consistent posterior members than the ensemble Kalman filter, which leads to fewer spurious model adjustments during forecasts. This manuscript presents the first successful application of the local PF in a weather prediction model and discusses implications for real applications where nonlinear measurement operators and nonlinear model processes limit the effectiveness of current Gaussian data assimilation techniques. © 2017 American Meteorological Society."
"36106335800;7501627905;","An aerosol activation metamodel of v1.2.0 of the pyrcel cloud parcel model: Development and offline assessment for use in an aerosol-climate model",2017,"10.5194/gmd-10-1817-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018291283&doi=10.5194%2fgmd-10-1817-2017&partnerID=40&md5=7919b6ffc2eb07a0fbcdaf303d9dd30a","We describe an emulator of a detailed cloud parcel model which has been trained to assess droplet nucleation from a complex, multimodal aerosol size distribution simulated by a global aerosol-climate model. The emulator is constructed using a sensitivity analysis approach (polynomial chaos expansion) which reproduces the behavior of the targeted parcel model across the full range of aerosol properties and meteorology simulated by the parent climate model. An iterative technique using aerosol fields sampled from a global model is used to identify the critical aerosol size distribution parameters necessary for accurately predicting activation. Across the large parameter space used to train them, the emulators estimate cloud droplet number concentration (CDNC) with a mean relative error of 9.2% for aerosol populations without giant cloud condensation nuclei (CCN) and 6.9% when including them. Versus a parcel model driven by those same aerosol fields, the best-performing emulator has a mean relative error of 4.6%, which is comparable with two commonly used activation schemes also evaluated here (which have mean relative errors of 2.9 and 6.7%, respectively). We identify the potential for regional biases in modeled CDNC, particularly in oceanic regimes, where our best-performing emulator tends to overpredict by 7%, whereas the reference activation schemes range in mean relative error from-3 to 7%. The emulators which include the effects of giant CCN are more accurate in continental regimes (mean relative error of 0.3%) but strongly overestimate CDNC in oceanic regimes by up to 22%, particularly in the Southern Ocean. The biases in CDNC resulting from the subjective choice of activation scheme could potentially influence the magnitude of the indirect effect diagnosed from the model incorporating it. © 2017 The Author(s)."
"57203078745;57153656200;38361063500;56400768700;57193990982;55365651300;6602506180;15725518800;7003440089;","Reconstructions of the 1900-2015 Greenland ice sheet surface mass balance using the regional climate MAR model",2017,"10.5194/tc-11-1015-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018190464&doi=10.5194%2ftc-11-1015-2017&partnerID=40&md5=d1e7f2c9936e22c5d25cd5d81a86f51d","With the aim of studying the recent Greenland ice sheet (GrIS) surface mass balance (SMB) decrease relative to the last century, we have forced the regional climate MAR (Modèle Atmosphérique Régional; version 3.5.2) model with the ERA-Interim (ECMWF Interim Re-Analysis; 1979-2015), ERA-40 (1958-2001), NCEP-NCARv1 (National Centers for Environmental Prediction-National Center for Atmospheric Research Reanalysis version 1; 1948- 2015), NCEP-NCARv2 (1979-2015), JRA-55 (Japanese 55-year Reanalysis; 1958-2014), 20CRv2(c) (Twentieth Century Reanalysis version 2; 1900-2014) and ERA-20C (1900- 2010) reanalyses. While all these forcing products are reanalyses that are assumed to represent the same climate, they produce significant differences in the MAR-simulated SMB over their common period. A temperature adjustment of C1 °C (respectively-1 °C) was, for example, needed at the MAR boundaries with ERA-20C (20CRv2) reanalysis, given that ERA-20C (20CRv2) is -1 °C colder (warmer) than ERAInterim over Greenland during the period 1980-2010. Comparisons with daily PROMICE (Programme for Monitoring of the Greenland Ice Sheet) near-surface observations support these adjustments. Comparisons with SMB measurements, ice cores and satellite-derived melt extent reveal the most accurate forcing datasets for the simulation of the GrIS SMB to be ERA-Interim and NCEP-NCARv1. However, some biases remain in MAR, suggesting that some improvements are still needed in its cloudiness and radiative schemes as well as in the representation of the bare ice albedo. Results from all MAR simulations indicate that (i) the period 1961-1990, commonly chosen as a stable reference period for Greenland SMB and ice dynamics, is actually a period of anomalously positive SMB (- C40 Gt yr-1) compared to 1900-2010; (ii) SMB has decreased significantly after this reference period due to increasing and unprecedented melt reaching the highest rates in the 120-year common period; (iii) before 1960, both ERA-20C and 20CRv2-forced MAR simulations suggest a significant precipitation increase over 1900-1950, but this increase could be the result of an artefact in the reanalyses that are not well-enough constrained by observations during this period and (iv) since the 1980s, snowfall is quite stable after having reached a maximum in the 1970s. These MAR-based SMB and accumulation reconstructions are, however, quite similar to those from Box (2013) after 1930 and confirm that SMB was quite stable from the 1940s to the 1990s. Finally, only the ERA-20Cforced simulation suggests that SMB during the 1920-1930 warm period over Greenland was comparable to the SMB of the 2000s, due to both higher melt and lower precipitation than normal."
"35490828000;56157868600;56118407000;6701606453;","Polar clouds and radiation in satellite observations, reanalyses, and climate models",2017,"10.1002/2016GL072242","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017415833&doi=10.1002%2f2016GL072242&partnerID=40&md5=0d99e136f0746fdc543b4e0915376330","Clouds play a pivotal role in the surface energy budget of the polar regions. Here we use two largely independent data sets of cloud and surface downwelling radiation observations derived by satellite remote sensing (2007–2010) to evaluate simulated clouds and radiation over both polar ice sheets and oceans in state-of-the-art atmospheric reanalyses (ERA-Interim and Modern Era Retrospective-Analysis for Research and Applications-2) and the Coupled Model Intercomparison Project Phase 5 (CMIP5) climate model ensemble. First, we show that, compared to Clouds and the Earth's Radiant Energy System-Energy Balanced and Filled, CloudSat-CALIPSO better represents cloud liquid and ice water path over high latitudes, owing to its recent explicit determination of cloud phase that will be part of its new R05 release. The reanalyses and climate models disagree widely on the amount of cloud liquid and ice in the polar regions. Compared to the observations, we find significant but inconsistent biases in the model simulations of cloud liquid and ice water, as well as in the downwelling radiation components. The CMIP5 models display a wide range of cloud characteristics of the polar regions, especially with regard to cloud liquid water, limiting the representativeness of the multimodel mean. A few CMIP5 models (CNRM, GISS, GFDL, and IPSL_CM5b) clearly outperform the others, which enhances credibility in their projected future cloud and radiation changes over high latitudes. Given the rapid changes in polar regions and global feedbacks involved, future climate model developments should target improved representation of polar clouds. To that end, remote sensing observations are crucial, in spite of large remaining observational uncertainties, which is evidenced by the substantial differences between the two data sets. ©2017. The Authors."
"36731938300;6701581547;57193908219;57021138000;55399842300;25651961100;","The effects of teleconnections on carbon fluxes of global terrestrial ecosystems",2017,"10.1002/2016GL071743","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017467713&doi=10.1002%2f2016GL071743&partnerID=40&md5=93227520e21f40743c5d049868ec5819","Large-scale atmospheric circulation patterns (i.e., teleconnections) influence global climate variability patterns and can be studied to provide a simple framework for relating the complex response of ecosystems to climate. This study analyzes the effects of 15 major teleconnections on terrestrial ecosystem carbon fluxes during 1951–2012 using an ensemble of nine dynamic global vegetation models. We map the global pattern of the dominant teleconnections and find that these teleconnections significantly affect gross primary productivity variations over more than 82.1% of the global vegetated area, through mediating the global temperature and regional precipitation and cloud cover. The El Niño–Southern Oscillation, the Pacific Decadal Oscillation, and the Atlantic Multidecadal Oscillation are strongly correlated with global, hemispherical, and continental carbon fluxes and climatic variables, while the Northern Hemisphere teleconnections have only regional influences. Further research regarding the interactions among the teleconnections and the nonstationarity of the relationship between teleconnections and carbon fluxes is needed. ©2017. American Geophysical Union. All Rights Reserved."
"57133112900;6701580874;6603568514;7005265210;","Daily variability of California coastal low cloudiness: A balancing act between stability and subsidence",2017,"10.1002/2017GL073075","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017092609&doi=10.1002%2f2017GL073075&partnerID=40&md5=b76523fc17c7388c8c73425c9cd2b59c","We examine mechanisms driving daily variability of summer coastal low cloudiness (CLC) along the California coast. Daily CLC is derived from a satellite record from 1996 to 2014. Atmospheric rather than oceanic processes are mostly responsible for daily fluctuations in vertical stability that dictate short-period variation in CLC structure. Daily CLC anomalies are most strongly correlated to lower tropospheric stability anomalies to the north. The spatially offset nature of the cloud-stability relationship is a result of the balancing act that affects low cloudiness wherein subsidence drives increased stability, which promotes cloudiness, but too much subsidence limits cloudiness. Lay explanations claim that high inland temperatures “pull in” CLC, but such a process presumably would have the high temperatures directly inland. Rather, we find that the spatially offset associations between CLC and atmospheric circulation result in positive correlations between CLC and inland surface temperature anomalies to the north. ©2017. American Geophysical Union. All Rights Reserved."
"18437054200;21234333100;7407002527;6602880957;55476786400;56162279000;","Suomi NPP VIIRS/DNB imagery of nightglow gravity waves from various sources over China",2017,"10.1016/j.asr.2017.01.041","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012908945&doi=10.1016%2fj.asr.2017.01.041&partnerID=40&md5=7fae74dd091947ccce596a588935e29e","Observation of atmospheric gravity waves provides critical insight to weather and climate researches. Some gravity waves survive middle-atmospheric filtering as they propagate upward to the mesopause region and disturb the nightglow emission layer near 90 km AMSL, making the waves visible to both ground and space sensors. Based on the high-resolution images obtained by Day/Night Band on NOAA/NASA Suomi National Polar-orbiting Partnership environmental satellite, four representative gravity wave events over China are analyzed. With the help of VIIRS thermal infrared brightness temperature and MERRA wind data, we surmise that these waves originated from orography, thunderstorm, typhoon and baroclinic, respectively. Nadir viewing satellite observations cover a wide area and unlike the surface-based perspective, do not suffer from cloud obscuration. These new observations over remote areas provide important guidance for future deployment of ground based camera systems in China. © 2017 COSPAR"
"35847990900;7403046868;6602159345;6603331306;","Annual variation in event-scale precipitation δ2H at Barrow, AK, reflects vapor source region",2017,"10.5194/acp-17-4627-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017402255&doi=10.5194%2facp-17-4627-2017&partnerID=40&md5=be3b36e9464824d94fa3a8e81a0a5d6c","In this study, precipitation isotopic variations at Barrow, AK, USA, are linked to conditions at the moisture source region, along the transport path, and at the precipitation site. Seventy precipitation events between January 2009 and March 2013 were analyzed for δ2H and deuterium excess. For each precipitation event, vapor source regions were identified with the hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) air parcel tracking program in back-cast mode. The results show that the vapor source region migrated annually, with the most distal (proximal) and southerly (northerly) vapor source regions occurring during the winter (summer). This may be related to equatorial expansion and poleward contraction of the polar circulation cell and the extent of Arctic sea ice cover. Annual cycles of vapor source region latitude and δ2H in precipitation were in phase; depleted (enriched) δ2H values were associated with winter (summer) and distal (proximal) vapor source regions. Precipitation δ2H responded to variation in vapor source region as reflected by significant correlations between δ2H with the following three parameters: (1) total cooling between lifted condensation level (LCL) and precipitating cloud at Barrow, span styleCombining double low line text-decoration: overline T cool, (2) meteorological conditions at the evaporation site quantified by 2 m dew point, &lt;span styleCombining double low line""text-decoration: overline T d, and (3) whether the vapor transport path crossed the Brooks and/or Alaskan ranges, expressed as a Boolean variable, m n. These three variables explained 54% of the variance (p&lt;0. 001) in precipitation δ2H with a sensitivity of g-3.51±0.55% °Cg-1 (&lt;0. 001) to &lt;span styleCombining double low linetext-decoration: overline T cool, 3.23±0.83% °Cg-1 (p &lt;0. 001) to Td, and g-32.11±11.04% (p Combining double low line 0. 0049) depletion when mn is true. The magnitude of each effect on isotopic composition also varied with vapor source region proximity. For storms with proximal vapor source regions (where &lt;span styleCombining double low line""text-decoration: overline; T cool 7°C), span styleCombining double low line""text-decoration: overline T cool explained 3% of the variance in δ2H, span styleCombining double low line text-decoration: overline T d alone accounted for 43%, while mtn explained 2%. For storms with distal vapor sources (span styleCombining double low line""text-decoration: overlineT cool 7°C), span styleCombining double low line text-decoration: overline;"" Tcool explained 22%, span styleCombining double low line""text-decoration: Td explained only 1%, and in explained 18%. The deuterium excess annual cycle lagged by 2-3 months during the δ2H cycle, so the direct correlation between the two variables is weak. Vapor source region relative humidity with respect to the sea surface temperature, &lt;span styleCombining double low line""text-decoration: overline &gt; &gt;hss, explained 34% of variance in deuterium excess, (g-0.395±0.067% %g-1, p&lt;0. 001). The patterns in our data suggest that on an annual scale, isotopic ratios of precipitation at Barrow may respond to changes in the southerly extent of the polar circulation cell, a relationship that may be applicable to interpretation of long-term climate change records like ice cores. © 2017 Author(s)."
"7005450157;57199140084;55515080000;56041424300;51563318700;53663406200;9736164500;55413710900;7801388948;","Radiometric flight results from the HyperSpectral Imager for Climate Science (HySICS)",2017,"10.5194/gi-6-169-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017174676&doi=10.5194%2fgi-6-169-2017&partnerID=40&md5=062a275907c2cf6bf7b0f95c16b9a390","Long-term monitoring of the Earth-reflected solar spectrum is necessary for discerning and attributing changes in climate. High radiometric accuracy enables such monitoring over decadal timescales with non-overlapping instruments, and high precision enables trend detection on shorter timescales. The HyperSpectral Imager for Climate Science (HySICS) is a visible and near-infrared spatial/spectral imaging spectrometer intended to ultimately achieve ∼ 0.2% radiometric accuracies of Earth scenes from space, providing an order-of-magnitude improvement over existing space-based imagers. On-orbit calibrations from measurements of spectral solar irradiances acquired by direct views of the Sun enable radiometric calibrations with superior long-term stability than is currently possible with any manmade spaceflight light source or detector. Solar and lunar observations enable in-flight focal-plane array (FPA) flat-fielding and other instrument calibrations. The HySICS has demonstrated this solar cross-calibration technique for future spaceflight instrumentation via two high-altitude balloon flights. The second of these two flights acquired high-radiometric-accuracy measurements of the ground, clouds, the Earth's limb, and the Moon. Those results and the details of the uncertainty analyses of those flight data are described. © 2017 Author(s)."
"55445972400;57208462871;","Comparing multiple model-derived aerosol optical properties to spatially collocated ground-based and satellite measurements",2017,"10.5194/acp-17-4451-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017000390&doi=10.5194%2facp-17-4451-2017&partnerID=40&md5=49b0da23230454f3624991d7a9843244","Anthropogenic aerosols are a key factor governing Earth's climate and play a central role in human-caused climate change. However, because of aerosols' complex physical, optical, and dynamical properties, aerosols are one of the most uncertain aspects of climate modeling. Fortunately, aerosol measurement networks over the past few decades have led to the establishment of long-Term observations for numerous locations worldwide. Further, the availability of datasets from several different measurement techniques (such as ground-based and satellite instruments) can help scientists increasingly improve modeling efforts. This study explores the value of evaluating several model-simulated aerosol properties with data from spatially collocated instruments. We compare aerosol optical depth (AOD; total, scattering, and absorption), single-scattering albedo (SSA), Ångström exponent (<i>α</i>), and extinction vertical profiles in two prominent global climate models (Geophysical Fluid Dynamics Laboratory, GFDL, CM2.1 and CM3) to seasonal observations from collocated instruments (AErosol RObotic NETwork, AERONET, and Cloud-Aerosol Lidar with Orthogonal Polarization, CALIOP) at seven polluted and biomass burning regions worldwide. We find that a multi-parameter evaluation provides key insights on model biases, data from collocated instruments can reveal underlying aerosol-governing physics, column properties wash out important vertical distinctions, and <q>improved</q> models does not mean all aspects are improved. We conclude that it is important to make use of all available data (parameters and instruments) when evaluating aerosol properties derived by models. © Author(s) 2017."
"7103246957;36895628100;7102933062;","Revisiting hydrometeorology using cloud and climate observations",2017,"10.1175/JHM-D-16-0203.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017387637&doi=10.1175%2fJHM-D-16-0203.1&partnerID=40&md5=167a14f16919b382aa232d3a41683d64","This paper uses 620 station years of hourly Canadian Prairie climate data to analyze the coupling of monthly near-surface climate with opaque cloud, a surrogate for radiation, and precipitation anomalies. While the cloud-climate coupling is strong, precipitation anomalies impact monthly climate for as long as 5 months. The April climate has memory of precipitation anomalies back to freeze-up in November, mostly stored in the snowpack. The summer climate has memory of precipitation anomalies back to the beginning of snowmelt in March. In the warm season, mean temperature is strongly correlated to opaque cloud anomalies, but only weakly to precipitation anomalies. Mixing ratio anomalies are correlated to precipitation, but only weakly to cloud. The diurnal cycle of mixing ratio shifts upward with increasing precipitation anomalies. Positive precipitation anomalies are coupled to a lower afternoon lifting condensation level and a higher afternoon equivalent potential temperature; both favor increased convection and precipitation. Regression coefficients on precipitation increase from wet to dry conditions. This is consistent with increased uptake of soil water when monthly precipitation is low, until drought conditions are reached, and also consistent with gravity satellite observations. Regression analysis shows monthly opaque cloud cover is tightly correlated to three climate variables that are routinely observed: diurnal temperature range, mean temperature, and mean relative humidity. The set of correlation coefficients, derived from cloud and climate observations, could be used to evaluate the representation of the land-cloud-atmosphere system in both forecast and climate models. © 2017 American Meteorological Society."
"55427995800;14044758700;7102425008;7006019301;6506298579;45661986200;","Using satellite and reanalysis data to evaluate the representation of latent heating in extratropical cyclones in a climate model",2017,"10.1007/s00382-016-3204-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976295587&doi=10.1007%2fs00382-016-3204-6&partnerID=40&md5=d7a78f465c69237b42e8400e2db5b520","Extratropical cyclones are a key feature of the weather in the extratropics, which climate models need to represent in order to provide reliable projections of future climate. Extratropical cyclones produce significant precipitation and the associated latent heat release can play a major role in their development. This study evaluates the ability of a climate model, HiGEM, to represent latent heating in extratropical cyclones. Remote sensing data is used to investigate the ability of both the climate model and ERA-Interim (ERAI) reanalysis to represent extratropical cyclone cloud features before latent heating itself is assessed. An offline radiance simulator, COSP, and the ISCCP and CloudSat datasets are used to evaluate comparable fields from HiGEM and ERAI. HiGEM is found to exhibit biases in the cloud structure of extratropical cyclones, with too much high cloud produced in the warm conveyor belt region compared to ISCCP. Significant latent heating occurs in this region, derived primarily from HiGEM’s convection scheme. ERAI is also found to exhibit biases in cloud structure, with more clouds at lower altitudes than those observed in ISCCP in the warm conveyor belt region. As a result, latent heat release in ERAI is concentrated at lower altitudes. CloudSat indicates that much precipitation may be produced at too low an altitude in both HiGEM and ERAI, particularly ERAI, and neither capture observed variability in precipitation intensity. The potential vorticity structure in composite extratropical cyclones in HiGEM and ERAI is also compared. A more pronounced tropopause ridge evolves in HiGEM on the leading edge of the composite as compared to ERAI. One future area of research to be addressed is what impact these biases in the representation of latent heating have on climate projections produced by HiGEM. The biases found in ERAI indicate caution is required when using reanalyses to study cloud features and precipitation processes in extratropical cyclones or using reanalysis to evaluate climate models’ ability to represent their structure. © 2016, The Author(s)."
"36627288300;","Clouds in the atmospheres of extrasolar planets: V. the impact of CO 2 ice clouds on the outer boundary of the habitable zone",2017,"10.1051/0004-6361/201630029","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017375930&doi=10.1051%2f0004-6361%2f201630029&partnerID=40&md5=d3923b44d3e87de662acd55b542e7ad5","Clouds have a strong impact on the climate of planetary atmospheres. The potential scattering greenhouse effect of CO2 ice clouds in the atmospheres of terrestrial extrasolar planets is of particular interest because it might influence the position and thus the extension of the outer boundary of the classic habitable zone around main sequence stars. Here, the impact of CO2 ice clouds on the surface temperatures of terrestrial planets with CO2 dominated atmospheres, orbiting different types of stars is studied. Additionally, their corresponding effect on the position of the outer habitable zone boundary is evaluated. For this study, a radiative-convective atmospheric model is used the calculate the surface temperatures influenced by CO2 ice particles. The clouds are included using a parametrised cloud model. The atmospheric model includes a general discrete ordinate radiative transfer that can describe the anisotropic scattering by the cloud particles accurately. A net scattering greenhouse effect caused by CO2 clouds is only obtained in a rather limited parameter range which also strongly depends on the stellar effective temperature. For cool M-stars, CO2 clouds only provide about 6 K of additional greenhouse heating in the best case scenario. On the other hand, the surface temperature for a planet around an F-type star can be increased by 30 K if carbon dioxide clouds are present. Accordingly, the extension of the habitable zone due to clouds is quite small for late-type stars. Higher stellar effective temperatures, on the other hand, can lead to outer HZ boundaries about 0.5 au farther out than the corresponding clear-sky values. © ESO, 2017."
"22982141200;57194228945;55731174900;57203321797;","Diurnal temperature range in CMIP5 models and observations on the Tibetan Plateau",2017,"10.1002/qj.3057","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019358110&doi=10.1002%2fqj.3057&partnerID=40&md5=25c6b184ce63524fbe9d4d25be86941e","The diurnal temperature range (DTR), defined as the difference between the maximum and minimum temperature, is a useful diagnostic index for evaluating global climate models. In this study, the DTR from 17 GCMs available in the fifth phase of the Coupled Model Intercomparison Project (CMIP5) is evaluated on the Tibetan Plateau (TP) by comparison with the observations during 1961–2005. During the studied period, the observed maximum/minimum temperatures on the TP show statistically increasing trends with the annual rates of 0.19/0.36 °C decade−1, respectively, leading to the reduction of DTR (−0.22 °C decade−1). Compared with the observed DTR, most CMIP5 models generally underestimate DTR, with absolute error ranging from −4.58 °C (GFDL-ESM2M) to −1.36 °C (CESM1-BGC). Fifteen CMIP5 models have reproduced the overall negative trends of DTR on the TP, but their trend magnitudes are smaller. Furthermore, the CMIP5 model biases in DTR are investigated by means of correlative approach, to reveal the dominant variables. The differences between the surface downwelling short-wave radiation (SDSR) with clear skies (SDSRcs) and the SDSR can be used to describe the surface short-wave cloud radiative effect. Similarly, the differences between the surface downwelling long-wave radiation (SDLR) and the SDLR with clear skies (SDLRcs) are defined to address the surface long-wave cloud radiative effect. It is found that the mean DTR in the CMIP5 models has significantly negative correlations with both SDLR–SDLRcs and SDSRcs–SDSR, suggesting that the model differences in DTR on the TP are probably determined by radiation variables and total cloud fraction in the CMIP5 models. © 2017 Royal Meteorological Society"
"55704387600;13204458100;6701599239;8680433600;36722293600;","A global multilayer cloud identification with POLDER/PARASOL",2017,"10.1175/JAMC-D-16-0159.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017497714&doi=10.1175%2fJAMC-D-16-0159.1&partnerID=40&md5=38bd06f6e03cd5b2d439da18c950cb34","The detection of multilayer cloud situations is important for satellite retrieval algorithms and for many climate-related applications. In this paper, the authors describe an algorithm based on the exploitation of the Polarization and Directionality of the Earth's Reflectance (POLDER) observations to identify monolayered and multilayered cloudy situations along with a confidence index. The authors' reference comes from the synergy of the active instruments of the A-Train satellite constellation. The algorithm is based upon a decision tree that uses a metric from information theory and a series of tests on POLDER level-2 products. The authors obtain a multilayer flag as the final result of a tree classification, which takes discrete values between 0 and 100. Values closest to 0 (100) indicate a higher confidence in the monolayer (multilayer) character. This indicator can be used as it is or with a threshold level that minimizes the risk of misclassification, as a binary index to distinguish between monolayer and multilayer clouds. For almost fully covered and optically thick enough cloud scenes, the risk of misclassification ranges from 29% to 34% over the period 2006-10, and the average confidences in the estimated monolayer and multilayer characters of the cloud scenes are 74.0% and 58.2%, respectively. With the binary distinction, POLDER provides a climatology of the mono-multilayer cloud character that exhibits some interesting features. Comparisons with the performance of the Moderate Resolution Imaging Spectroradiometer (MODIS) multilayer flag are given. © 2017 American Meteorological Society."
"23479921600;7102795549;56461745000;36705143500;55476830600;7004063850;7403364008;36105812700;26531118000;","Smaller desert dust cooling effect estimated from analysis of dust size and abundance",2017,"10.1038/ngeo2912","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016960348&doi=10.1038%2fngeo2912&partnerID=40&md5=dbe19623d74928a60c5362f57b46d344","Desert dust aerosols affect Earth's global energy balance through direct interactions with radiation, and through indirect interactions with clouds and ecosystems. But the magnitudes of these effects are so uncertain that it remains unclear whether atmospheric dust has a net warming or cooling effect on global climate. Consequently, it is still uncertain whether large changes in atmospheric dust loading over the past century have slowed or accelerated anthropogenic climate change, or what the effects of potential future changes in dust loading will be. Here we present an analysis of the size and abundance of dust aerosols to constrain the direct radiative effect of dust. Using observational data on dust abundance, in situ measurements of dust optical properties and size distribution, and climate and atmospheric chemical transport model simulations of dust lifetime, we find that the dust found in the atmosphere is substantially coarser than represented in current global climate models. As coarse dust warms the climate, the global dust direct radiative effect is likely to be less cooling than the 1/40.4 W m2 estimated by models in a current global aerosol model ensemble. Instead, we constrain the dust direct radiative effect to a range between 0.48 and +0.20 W m 2, which includes the possibility that dust causes a net warming of the planet. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved."
"56998738300;7006894780;37088140000;","Spatio-temporal variance and meteorological drivers of the urban heat island in a European city",2017,"10.1007/s00704-015-1687-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949568926&doi=10.1007%2fs00704-015-1687-4&partnerID=40&md5=e3c4973b96ab88c225090c25e611b697","Urban areas are especially vulnerable to high temperatures, which will intensify in the future due to climate change. Therefore, both good knowledge about the local urban climate as well as simple and robust methods for its projection are needed. This study has analysed the spatio-temporal variance of the mean nocturnal urban heat island (UHI) of Hamburg, with observations from 40 stations from different suppliers. The UHI showed a radial gradient with about 2 K in the centre mostly corresponding to the urban densities. Temporarily, it has a strong seasonal cycle with the highest values between April and September and an inter-annual variability of approximately 0.5 K. Further, synoptic meteorological drivers of the UHI were analysed, which generally is most pronounced under calm and cloud-free conditions. Considered were meteorological parameters such as relative humidity, wind speed, cloud cover and objective weather types. For the stations with the highest UHI intensities, up to 68.7 % of the variance could be explained by seasonal empirical models and even up to 76.6 % by monthly models. © 2015, Springer-Verlag Wien."
"37761920800;16174785900;7101755965;","Coating surface tension dependence of soot aggregate restructuring",2017,"10.1016/j.jaerosci.2017.01.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009921433&doi=10.1016%2fj.jaerosci.2017.01.005&partnerID=40&md5=924ae58a294f74e691e64a30b9f0a060","Atmospheric aerosols affect climate directly, by absorbing and scattering solar radiation, and indirectly, by altering cloud albedo and lifetime. Here, using a tandem differential mobility analyzer and a numerical model, we demonstrate that the restructuring of soot aggregates due to liquid coatings increases with the surface tension of the coating material. The agreement between the experimental and numerical modelling results further demonstrates that restructuring occurs upon coating condensation, not evaporation. These findings provide constraints on the direct effect of black carbon. In turn, using soot aggregates as novel nano-probes, we estimate the surface tension of secondary organic aerosol derived from the photo-oxidation of m-xylene to be 38 ± 3 mN m−1 under the present experimental conditions. Since surface tension influences nucleation and condensational growth, processes which lead to particles large enough to act as cloud condensation nuclei, our measurement provides an important constraint on the indirect effect of secondary organic aerosol. © 2017 Elsevier Ltd"
"57194172650;7006790016;7006033615;55857208900;7005869374;","Dominant covarying climate signals in the southern ocean and antarctic sea ice influence during the last three decades",2017,"10.1175/JCLI-D-16-0439.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018485140&doi=10.1175%2fJCLI-D-16-0439.1&partnerID=40&md5=a6edd92664746a8c673b9e6af6cbbb40","A composite dataset (comprising geopotential height, sea surface temperature, zonal and meridional surface winds, precipitation, cloud cover, surface air temperature, latent plus sensible heat fluxes, and sea ice concentration) has been investigated with the aim of revealing the dominant time scales of variability from 1982 to 2013. Three covarying climate signals associated with variations in the sea ice distribution around Antarctica have been detected through the application of the multiple-taper method with singular value decomposition (MTM-SVD). Features of the established patterns of variation over the Southern Hemisphere extratropics have been identified in each of these three climate signals in the form of coupled or individual oscillations. The climate patterns considered here are the southern annular mode (SAM), the Pacific-South American (PSA) teleconnection, the semiannual oscillation (SAO), and the zonal wavenumber-3 (ZW3) mode. It is shown that most of the sea ice temporal variance is concentrated at the quasi-triennial scale resulting from the constructive superposition of the PSA and ZW3 patterns. In addition, the combination of the SAM and SAO patterns is found to promote the interannual sea ice variations underlying a general change in the Southern Ocean atmospheric and oceanic circulations. These two modes of variability are also found to be consistent with the occurrence of the positive SAM/negative PSA (SAM+/PSA-) or negative SAM/positive PSA (SAM-/PSA+) combinations, which could have favored the cooling of the sub-Antarctic region and important changes in the Antarctic sea ice distribution since 2000. © 2017 American Meteorological Society."
"57190986692;22233326100;36459641300;55892478400;57006227400;","Climate- and human-induced changes in suspended particulate matter over Lake Hongze on short and long timescales",2017,"10.1016/j.rse.2017.02.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012110587&doi=10.1016%2fj.rse.2017.02.007&partnerID=40&md5=9060ca4bfdf5e5eb685187de2c6f2233","Changes in global climate drivers have multiple impacts on lake ecosystems, as rain and wind conditions control catchment surface runoff and lake mixing regimes. However, human activities in lakes and their watersheds may have direct and indirect impacts on aquatic optical properties. Therefore, identifying key drivers that can be controlled (human) from those that cannot (climate) represents an important objective. In the present study, we develop an algorithm to estimate the concentrations of suspended particulate matter (SPM) in Lake Hongze (the fourth largest freshwater lake in China) using MODIS/Aqua images with concurrent data collected from six cruise surveys. The algorithm resulted in root mean square errors (RMSEs) of 7.64–7.86 mg/L for SPM ranging from 10 to 80 mg/L. The algorithm was applied to 1602 cloud-free MODIS/Aqua images from 2002 to 2015. Our results show: (1) inter-annual and seasonal variations of SPM concentrations in Lake Hongze are divided into two distinct periods between 2002 and 2011 and 2012–2015, with the transition associated to intensive dredging activities that were initiated in 2012. (2) SPM concentrations exhibit four typical patterns of spatial distribution which depend on local meteorological (wind speed and wind direction) and hydrological conditions (catchment rainfall and Huai River flowrate). Based on these results, a new spatial zoning of the lake is derived to support government and agency monitoring. The study shows additive and synergistic effects of climate change and human activities on SPM concentrations over short and long timescales and the possibility to monitor these changes by remote sensing in shallow optically complex lakes. © 2017 Elsevier Inc."
"57194391209;6602871700;","OLR perspective on the Indian Ocean Dipole with application to East African precipitation",2017,"10.1002/qj.3045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019964302&doi=10.1002%2fqj.3045&partnerID=40&md5=82eb1f76d3983d48635c4ed17e6addd4","Interannual variability of precipitation over eastern Africa (Somalia, Ethiopia, and Kenya) is impacted by the Indian Ocean dipole (IOD), which has its maximum amplitude during autumn. During northern spring, sea-surface temperature (SST) in the tropical Indian Ocean is nearly always sufficiently high to sustain convection, but it exhibits no clear pattern of variability. Thus, precipitation variability over Eastern Africa during spring is not connected to any Indian Ocean interannual mode sustained by SST anomalies. Yet, seasonal variability in atmospheric convection might sustain interannual modes during spring independent of SST. We construct an index for the IOD based on outgoing long-wave radiation anomaly (OLRA) instead of SST anomaly. During northern spring, analysis of this index shows that interannual precipitation over Eastern Africa is correlated with interannual variability similar to the IOD, as measured by OLR. The largest part of that relationship originates from the western Indian Ocean, with smaller contributions from the eastern Indian Ocean. Results indicate that atmospheric convection over the tropical Indian Ocean couples the atmospheric circulation over the eastern and western Indian basin irrespective of SST anomalies. Results from constructed analogue analysis show that positive SST anomaly during northern winter caused by persistence of subsidence and cloud–radiation–SST negative feedback over the southeastern Indian Ocean from the previous positive IOD is associated with formation of negative IOD later during the following autumn. © 2017 Royal Meteorological Society"
"55995777500;57189241924;57202656048;57205864292;28168059300;49664585700;","Snow Cover Monitoring in Qinghai-Tibetan Plateau Based on Chinese Fengyun-3/VIRR Data",2017,"10.1007/s12524-015-0527-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966621777&doi=10.1007%2fs12524-015-0527-4&partnerID=40&md5=498d30473c07d2892728ec11c72368ac","Snow cover monitoring in the Qinghai-Tibetan Plateau is very important to global climate change research. Because of the geographic distribution of ground meteorological stations in Qinghai-Tibetan Plateau is too sparse, satellite remote sensing became the only choice for snow cover monitoring in Qinghai-Tibetan Plateau. In this paper, multi-channel data from Visible and Infrared Radiometer (VIRR) on Chinese polar orbiting meteorological satellites Fengyun-3(FY-3) are utilized for snow cover monitoring, in this work, the distribution of snow cover is extracted from the normalized difference snow index(NDSI), and the multi-channel threshold from the brightness temperature difference in infrared channels. Then, the monitoring results of FY-3A and FY-3B are combined to generate the daily composited snow cover product. Finally, the snow cover products from MODIS and FY-3 are both verified by snow depth of meteorological station observations, result shows that the FY-3 products and MODIS products are basically consistent, the overall accuracy of FY-3 products is higher than MODIS products by nearly 1 %. And the cloud coverage rate of FY-3 products is less than MODIS by 2.64 %. This work indicates that FY-3/VIRR data can be reliable data sources for monitoring snow cover in the Qinghai-Tibetan Plateau. © 2015, Indian Society of Remote Sensing."
"57209589566;6701754792;55717881500;55782381000;","Sensitivity of the ACCESS forecast model statistical rainfall properties to resolution",2017,"10.1002/qj.3056","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019837619&doi=10.1002%2fqj.3056&partnerID=40&md5=9f5b1b6ef17737f7e2baae33d01391b4","The representation of the statistical properties of rainfall over Darwin is assessed in four versions of the Australian Community Climate and Earth-System Simulator (ACCESS) forecast model against the dual-polarization C-band polarimetric (CPOL) radar observation for one rainy season (November 2014 to April 2015). This is an extended analysis of a companion study assessing the earlier version of the regional ACCESS-12 km rainfall properties with the same CPOL observations. By comparing four different horizontal resolutions (40, 12, 4 and 1.5 km) of ACCESS, it is shown that increasing resolution results in improved total domain rainfall but does not change the compensation effect of underestimated intensity and overestimated frequency of occurrence. In all versions where the convective parametrization is still turned on, a strong and spurious land–sea contrast with too much rain over ocean not exporting to land is found. This problem is only solved by switching off the convective parametrization in the model (1.5 km resolution). However, in this explicit version, high rain rates are this time largely overestimated, resulting in a similar order of magnitude of the mean daily rainfall bias as when convection is parametrized, albeit with a different spatial distribution. The diurnal peak of hourly rain rates is also found to occur too early (around noon at the maximum insolation) when convection is parametrized, but is correct (around 1500 local time) when convection is explicit. More work needs to be done to assess if these errors are common to most cloud-resolving models, and to solve these two main issues of excessive rainfall in the explicit version of the model and artificial land–sea contrast in the parametrized version of the model. © 2017 Commonwealth of Australia. Quarterly Journal of the Royal Meteorological Society © 2017 Royal Meteorological Society"
"15767938100;54683899900;6602369002;23009866300;6602267589;","Skill of ECMWF system-4 ensemble seasonal climate forecasts for East Africa",2017,"10.1002/joc.4876","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84997125497&doi=10.1002%2fjoc.4876&partnerID=40&md5=a04eb1748f8166c874e684d3ea3bc85a","This study evaluates the potential use of the ECMWF System-4 seasonal forecasts (S4) for impact analysis over East Africa. For use, these forecasts should have skill and small biases. We used the 15-member ensemble of 7-month forecasts initiated every month, and tested forecast skill of precipitation (tp), near-surface air temperature (tas) and surface downwelling shortwave radiation (rsds). We validated the 30-year (1981–2010) hindcast version of S4 against the WFDEI reanalysis (WATCH Forcing Data ERA-Interim) and to independent relevant observational data sets. Probabilistic skill is assessed using anomaly correlation, ranked probability skill score (RPSS) and the relative operating curve skill score (ROCSS) at both grid cell and over six distinct homogeneous rainfall regions for the three growing seasons of East Africa (i.e. MAM, JJA and OND). S4 exhibits a wet bias in OND, a dry bias in MAM and a mix of both in JJA. Temperature biases are similar in all seasons, constant with lead-time and correlate with elevation. Biases in rsds correlate with cloud/rain patterns. Bias correction clears biases but does not affect probabilistic skills. Predictability of the three variables varies with season, location and lead-time. The choice of validating dataset plays little role in the regional patterns and magnitudes of probabilistic skill scores. The OND tp forecasts show skill over a larger area up to 3 months lead-time compared to MAM and JJA. Upper- and lower-tercile tp forecasts are 20–80% better than climatology. Temperature forecasts are skillful for at least 3 months lead-time and they are 40–100% better than climatology. The rsds is less skillful than tp and tas in all seasons when verified against WFDEI but higher in all lead months against the alternative datasets. The forecast system captures El-Niño Southern Oscillation (ENSO)-related anomalous years with region-dependent skill. © 2016 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"55427995800;7102805852;35204593500;7407104838;57161569700;7202899330;","Southern Ocean albedo, inter-hemispheric energy transports and the double ITCZ: global impacts of biases in a coupled model",2017,"10.1007/s00382-016-3205-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016239065&doi=10.1007%2fs00382-016-3205-5&partnerID=40&md5=bf1099a79a1ead75be8661aacd6cfe03","A causal link has been invoked between inter-hemispheric albedo, cross-equatorial energy transport and the double-Intertropical Convergence Zone (ITCZ) bias in climate models. Southern Ocean cloud biases are a major determinant of inter-hemispheric albedo biases in many models, including HadGEM2-ES, a fully coupled model with a dynamical ocean. In this study, targeted albedo corrections are applied in the Southern Ocean to explore the dynamical response to artificially reducing these biases. The Southern Hemisphere jet increases in strength in response to the increased tropical-extratropical temperature gradient, with increased energy transport into the mid-latitudes in the atmosphere, but no improvement is observed in the double-ITCZ bias or atmospheric cross-equatorial energy transport, a finding which supports other recent work. The majority of the adjustment in energy transport in the tropics is achieved in the ocean, with the response further limited to the Pacific Ocean. As a result, the frequently argued teleconnection between the Southern Ocean and tropical precipitation biases is muted. Further experiments in which tropical longwave biases are also reduced do not yield improvement in the representation of the tropical atmosphere. These results suggest that the dramatic improvements in tropical precipitation that have been shown in previous studies may be a function of the lack of dynamical ocean and/or the simplified hemispheric albedo bias corrections applied in that work. It further suggests that efforts to correct the double ITCZ problem in coupled models that focus on large-scale energetic controls will prove fruitless without improvements in the representation of atmospheric processes. © 2016, The Author(s)."
"39761284900;9632873300;35939829700;8510858800;7004914081;57190303046;26648162300;9249498200;16024614000;57201816838;57190298324;39761805500;6602759336;6602101632;25028734400;57203793324;","ICOADS Release 3.0: a major update to the historical marine climate record",2017,"10.1002/joc.4775","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979047279&doi=10.1002%2fjoc.4775&partnerID=40&md5=5194bc973cd2d03779162da1f690e623","We highlight improvements to the International Comprehensive Ocean-Atmosphere Data Set (ICOADS) in the latest Release 3.0 (R3.0; covering 1662–2014). ICOADS is the most widely used freely available collection of surface marine observations, providing data for the construction of gridded analyses of sea surface temperature, estimates of air–sea interaction and other meteorological variables. ICOADS observations are assimilated into all major atmospheric, oceanic and coupled reanalyses, further widening its impact. R3.0 therefore includes changes designed to enable effective exchange of information describing data quality between ICOADS, reanalysis centres, data set developers, scientists and the public. These user-driven innovations include the assignment of a unique identifier (UID) to each marine report – to enable tracing of observations, linking with reports and improved data sharing. Other revisions and extensions of the ICOADS' International Maritime Meteorological Archive common data format incorporate new near-surface oceanographic data elements and cloud parameters. Many new input data sources have been assembled, and updates and improvements to existing data sources, or removal of erroneous data, made. Coupled with enhanced ‘preliminary’ monthly data and product extensions past 2014, R3.0 provides improved support of climate assessment and monitoring, reanalyses and near-real-time applications. © 2016 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"55728968600;14325221500;57219425459;","Multi-year energy balance and carbon dioxide fluxes over a residential neighbourhood in a tropical city",2017,"10.1002/joc.4873","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988353005&doi=10.1002%2fjoc.4873&partnerID=40&md5=7bb9a3525af79b4f4e64e676f9ab28fa","Detailed eddy covariance measurements of radiation, energy and carbon dioxide fluxes over a residential neighbourhood of Singapore are presented. The measurements cover a period of ∼7 years and represent the longest set of flux data reported for a tropical city. Owing to its equatorial location, the observed radiation fluxes are uniformly high throughout the year. Annual changes in climate, energy fluxes and carbon dioxide exchange are therefore much less than observed in cities located outside the Tropics. The energy balance partitioning is nevertheless similar to that reported for subtropical and mid-latitude suburban sites. Across the entire study period and all weather conditions 53.6% of net radiation (3.222 GJ m−2 year−1) is partitioned into sensible and 39.4% into latent heat, respectively, resulting in a long-term daily Bowen ratio of ∼1.4. Significant variability exists in net radiation and sensible heat flux using a classification based on clouds and rainfall. Carbon dioxide fluxes are generally positive throughout the day with morning and evening peaks related to maxima in traffic volume separating lower day- from higher nighttime fluxes. Unlike in many other comparable suburban studies, net fluxes are generally higher during night- compared to daytime. The largest daily fluxes and most pronounced diurnal variability coincide with seasons when the flux footprint includes the highest proportion of vegetation, suggesting an important role for daytime sequestration and nighttime respiration to control the diurnal and seasonal variation. Carbon dioxide fluxes change little across the year given the absence of a heating season with an annual total mass flux of 6368 Mg CO2 km−2 year−1. Singapore provides a unique climatic context, and the present long-term study is expected to add robust statistics from the understudied (sub)tropical region to the global data set of urban energy and carbon dioxide fluxes, which is dominated by work conducted in mid- and high latitudes. © 2016 Royal Meteorological Society"
"6701744275;7003648299;7102567936;","Role of the convection scheme in modeling initiation and intensification of tropical depressions over the North Atlantic",2017,"10.1175/MWR-D-16-0201.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017138062&doi=10.1175%2fMWR-D-16-0201.1&partnerID=40&md5=bb1561e7d17df0c750e947b3bf697c23","The authors analyze how modifications of the convective scheme modify the initiation of tropical depression vortices (TDVs) and their intensification into stronger warm-cored tropical cyclone-like vortices (TCs) in global climate model (GCM) simulations. The model's original convection scheme has entrainment and cloud-base mass flux closures based on moisture convergence. Two modifications are considered: one in which entrainment is dependent on relative humidity and another in which the closure is based on the convective available potential energy (CAPE). Compared to reanalysis, TDVs are more numerous and intense in all three simulations, probably as a result of excessive parameterized deep convection at the expense of convection detraining at midlevel. The relative humidity-dependent entrainment rate increases both TDV initiation and intensification relative to the control. This is because this entrainment rate is reduced in the moist center of the TDVs, giving more intense convective precipitation, and also because it generates a moister environment that may favor the development of early stage TDVs. The CAPE closure inhibits the parameterized convection in strong TDVs, thus limiting their development despite a slight increase in the resolved convection. However, the maximum intensity reached by TC-like TDVs is similar in the three simulations, showing the statistical character of these tendencies. The simulated TCs develop from TDVs with different dynamical origins than those observed. For instance, too many TDVs and TCs initiate near or over southern West Africa in the GCM, collocated with the maximum in easterly wave activity, whose characteristics are also dependent on the convection scheme considered. © 2017 American Meteorological Society."
"55976161500;14422451100;56013567900;57183042900;16053167300;17339515000;57193494824;57193486884;56500661200;","Assessment of the modulation effect of rainfall on solar radiation availability at the Earth's surface",2017,"10.1002/met.1616","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014253903&doi=10.1002%2fmet.1616&partnerID=40&md5=6058e67182f64a5e9218572a5ec8366b","A significant proportion of the solar irradiance that reaches the Earth's surface is normally attenuated by atmospheric properties and overcast conditions related to the rainy season. The Solar Analyst (SA) model, irradiance and long term precipitation data were used to assess this relationship in Guadalajara, Mexico. A spatial analysis based on morphological and statistical criteria increased the model's certainty. The SA model explains 95.4% of the irradiation variability observed on the ground, with average uncertainties of 3.7% during clear sky conditions in the dry season and 4.4% on sunny days in the wet season. The meteorological data analysis shows that total precipitation in 2014 had an atypical temporal distribution and was slightly lower (12.6%) than the average from 1991 to 2012. A deficit of 39% in precipitation compared to the long term average was found in the first half of the season, which was later partially compensated. This deficit was interpreted as a temporary delay in high values of precipitation. Based on the potential average irradiation from the SA model and field observations, it can be concluded that overcast conditions related to rainfall through 2014 attenuated approximately 28.5% of the incoming solar energy. Taking the global energy balance into account, this fraction was higher in comparison to the energy proportion reflected by the cloud's albedo (ca 23%). These results suggest that both the high proportion of energy attenuated and atypical weather conditions may be local effects of large-scale phenomena such as the El Niño-Southern Oscillation. © 2017 Royal Meteorological Society"
"57140160700;7005659847;35621058500;7202141884;7003351429;57205842560;7006577245;7004607037;7003469326;7004494400;7005899926;37099534700;40661065000;56212055700;35568326100;57191473265;6701705691;55192470800;7004177770;57148462400;14066601400;55951906300;7102790108;7102113229;7101973570;6603698240;6602109913;8387523500;8562497500;7004307916;55053339600;8527523100;57198369516;","Spatio-temporal monitoring by ground-based and air- and space-borne lidars of a moderate Saharan dust event affecting southern Europe in June 2013 in the framework of the ADRIMED/ChArMEx campaign",2017,"10.1007/s11869-016-0447-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009274876&doi=10.1007%2fs11869-016-0447-7&partnerID=40&md5=bcf29e04a183c3569e9653fcede67c81","During the ADRIMED (Aerosol Direct Radiative Impact on the regional climate in the Mediterranean region) special observation period (SOP-1a), conducted in June 2013 in the framework of the ChArMEx (Chemistry-Aerosol Mediterranean Experiment) project, a moderate Saharan dust event swept the Western and Central Mediterranean Basin (WCMB) from west to east during a 9-day period between 16 and 24 June. This event was monitored from the ground by six EARLINET/ACTRIS (European Aerosol Research Lidar Network/Aerosols, Clouds, and Trace gases Research Infrastructure Network) lidar stations (Granada, Barcelona, Naples, Potenza, Lecce and Serra la Nave) and two ADRIMED/ChArMEx lidar stations specially deployed for the field campaign in Cap d’en Font and Ersa, in Minorca and Corsica Islands, respectively. The first part of the study shows the spatio-temporal monitoring of the dust event during its transport over the WCMB with ground-based lidar and co-located AERONET (Aerosol Robotic Network) Sun-photometer measurements. Dust layer optical depths, Ångström exponents, coarse mode fractions, linear particle depolarization ratios (LPDRs), dust layer heights and the dust radiative forcing estimated in the shortwave (SW) and longwave (LW) spectral ranges at the bottom of the atmosphere (BOA) and at the top of the atmosphere (TOA) with the Global Atmospheric Model (GAME), have been used to characterize the dust event. Peak values of the AERONET aerosol optical depth (AOD) at 440 nm ranged between 0.16 in Potenza and 0.37 in Cap d’en Font. The associated Ångström exponent and coarse mode fraction mean values ranged from 0.43 to 1.26 and from 0.25 to 0.51, respectively. The mineral dust produced a negative SW direct radiative forcing at the BOA ranging from −56.9 to −3.5 W m−2. The LW radiative forcing at the BOA was positive, ranging between +0.3 and +17.7 W m-2. The BOA radiative forcing estimates agree with the ones reported in the literature. At the TOA, the SW forcing varied between −34.5 and +7.5 W m−2. In seven cases, the forcing at the TOA resulted positive because of the aerosol strong absorbing properties (0.83 &lt; single-scattering albedo (SSA) &lt; 0.96). The multi-intrusion aspect of the event is examined by means of air- and space-borne lidar measurements, satellite images and back trajectories. The analysis reported in this paper underline the arrival of a second different intrusion of mineral dust observed over southern Italy at the end of the considered period which probably results in the observed heterogeneity in the dust properties. © 2017, Springer Science+Business Media Dordrecht."
"24468389200;55754690200;57031538900;7404976222;","Two types of summertime heating over Asian large-scale orography and excitation of potential-vorticity forcing II. Sensible heating over Tibetan-Iranian Plateau",2017,"10.1007/s11430-016-9016-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015633509&doi=10.1007%2fs11430-016-9016-3&partnerID=40&md5=3d3c1e470992f3d40c66e9059f6b683a","Based on analysis and simulation, the interaction of thermal forcing between the Tibetan Plateau (TP) and Iranian Plateau (IP) in summer is investigated. Associated influences on water vapor transport in the Asian subtropical monsoon region and the formation of a cold center in the lower stratosphere over Eurasia are also investigated. Results show that surface sensible heating (SH) over the two plateaus not only have mutual influences but also feedback to each other. SH over the IP can reduce the SH and increase the LH over the TP, whereas the SH over the TP can increase surface heating over the IP, thereby reaching quasi-equilibrium among the SH and LH over the TP, IP SH and atmosphere vertical motion. Therefore, the so-called Tibetan-Iranian Plateau coupling system (TIPS) is constructed, which influences atmosphere circulation. In the TIPS system, interaction between surface SH and LH over the TP plays a leading role. SH of the IP and TP influences on other regions not only have superimposed effects but also mutually offset. Accounting for contributions to the convergence of water vapor transport in the Asian subtropical monsoon region, TP SH contributes more than twice that of the IP. The combined influence of SH over TP and IP represents the major contribution to the convergence of water vapor transport in that region. In addition, the heating effect of TIPS increases the upper tropospheric temperature maximum and lifts the tropopause, cooling the lower stratosphere. Combined with large-scale thermal forcing of the Eurasian continent, the TIPS produces a strong anticyclonic circulation and the South Asian High that warms the upper troposphere and cools the lower stratosphere, thereby affecting regional and global weather and climate. © 2017, Science China Press and Springer-Verlag Berlin Heidelberg."
"6603265463;6506943110;56312056400;6507979420;","Climate indicators for lightning over sea, sea–land mixed and land-only surfaces in India",2017,"10.1002/joc.4802","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015322803&doi=10.1002%2fjoc.4802&partnerID=40&md5=1c2d690a989a0989866f30dd8ed84911","In this article, we investigate indicators for lightning activity by analysing the data of surface heat flux, Bowen ratio (ratio of sensible to latent heats) and cloud base height for a period of 16 years (1998–2013) over Indo-Gangetic Plain (IGP) (25°–27°N, 80°–88°E), Indian land excluding IGP (8°–36°N, 68°–98°E) and 10 years (2000–2009) over Indian seas [Arabian Sea (5°–20°N, 65°–80°E) + Bay of Bengal (5°–20°N, 80°–98°E)]. Lightning activity varies with the surface heat flux, Bowen ratio and cloud base height over India. Over Indian land, annual lightning flash counts are found to be more by 32 and 24% than those over IGP and Indian seas, respectively. Total heat flux (sensible + latent) and lightning flash counts show a strong correlation coefficient of 0.75 for Indian land and 0.73 for IGP relative to that of Bowen ratio with lightning flash count (0.63 for Indian land and 0.19 for IGP). Hence, the total heat flux represents the best parameter for describing lightning activity over IGP and Indian land. Bowen ratio ≥1 in pre-monsoon increases lightning flash counts over IGP and Indian land. Cloud base height (a measure of moisture) and lightning flash counts show values in the order as Indian land > Indian seas > IGP. Geographic asymmetry of Indian land, IGP and Indian seas drive the continental and sea surface–atmosphere interactive processes that corroborate: (1) asymmetric synoptic scale delivery of moisture to Indian land and IGP from Indian seas revises the Bowen ratio, cloud base height and lightning activity, (2) increase in lightning activity with the total heat flux over Indian land and (3) enhance the lightning activity with the cloud base height/liquid condensation level. © 2016 Royal Meteorological Society"
"56888211000;6603779272;18437757900;","Influence of 2000-2050 climate change on particulate matter in the United States: Results from a new statistical model",2017,"10.5194/acp-17-4355-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016582916&doi=10.5194%2facp-17-4355-2017&partnerID=40&md5=b002b58d0da81bff254d518513472755","We use a statistical model to investigate the effect of 2000-2050 climate change on fine particulate matter (PM2.5) air quality across the contiguous United States. By applying observed relationships of PM2.5 and meteorology to the IPCC Coupled Model Intercomparision Project Phase 5 (CMIP5) archives, we bypass some of the uncertainties inherent in chemistry-climate models. Our approach uses both the relationships between PM2.5 and local meteorology as well as the synoptic circulation patterns, defined as the singular value decomposition (SVD) pattern of the spatial correlations between PM2.5 and meteorological variables in the surrounding region. Using an ensemble of 19 global climate models (GCMs) under the RCP4.5 scenario, we project an increase of 0.4-1.4μgm-3 in annual mean PM2.5 in the eastern US and a decrease of 0.3-1.2μgm-3 in the Intermountain West by the 2050s, assuming present-day anthropogenic sources of PM2.5. Mean summertime PM2.5 increases as much as 2-3μgm-3 in the eastern United States due to faster oxidation rates and greater mass of organic aerosols from biogenic emissions. Mean wintertime PM2.5 decreases by 0.3-3μgm-3 over most regions in the United States, likely due to the volatilization of ammonium nitrate. Our approach provides an efficient method to calculate the potential climate penalty on air quality across a range of models and scenarios. We find that current atmospheric chemistry models may underestimate or even fail to capture the strongly positive sensitivity of monthly mean PM2.5 to temperature in the eastern United States in summer, and they may underestimate future changes in PM2.5 in a warmer climate. In GEOS-Chem, the underestimate in monthly mean PM2.5-temperature relationship in the east in summer is likely caused by overly strong negative sensitivity of monthly mean low cloud fraction to temperature in the assimilated meteorology (∼-0.04-1) compared to the weak sensitivity implied by satellite observations (±0.01K-1). The strong negative dependence of low cloud cover on temperature in turn causes the modeled rates of sulfate aqueous oxidation to diminish too rapidly as temperatures rise, leading to the underestimate of sulfate-temperature slopes, especially in the south. Our work underscores the importance of evaluating the sensitivity of PM2.5 to its key controlling meteorological variables in climate-chemistry models on multiple timescales before they are applied to project future air quality. © 2017 Author(s)."
"7006734485;8204708800;57190441282;57190441483;57190436021;57190438567;57190440101;","Climatology of cold season lake-effect cloud bands for the North American Great Lakes",2017,"10.1002/joc.4838","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84980007083&doi=10.1002%2fjoc.4838&partnerID=40&md5=38170733939c649b419ddd1486d613bb","Geostationary Operational Environmental Satellite (GOES) visible imagery was used to identify lake-effect (LE) clouds in the North American Great Lakes region for the cold seasons (October–March) of 1997/1998 through 2013/2014 to provide a comprehensive climatological description of the seasonal and interannual variability of LE cloud bands. During the average cold season, at least 60% of days each month had LE clouds over some portion of the Great Lakes region and nearly 75% of all LE days had LE clouds present over several lakes simultaneously. Wind-parallel bands (WPB) are observed far more frequently than any other type of LE over Lakes Superior, Michigan, and Huron during the months of December, January, and February. Over Lake Erie, the occurrence of days per month with WPB was found to be approximately 5–10% greater than days with shore-parallel bands (SPBs) throughout the entire cold season. The greatest frequency of SPB occurrences in the Great Lakes region was over Lake Ontario during the months of January and February (∼20% of days). In addition, Lake Ontario was the only lake where the frequencies of WPB and SPB occurrences were fairly similar each month. The annual frequency of WPB occurrences are the most variable among the Great Lakes, decreasing in frequency from the western lakes toward the eastern lakes. Lake Ontario has the largest annual frequency of SPB occurrences and the greatest variation in SPB annual frequency. Lake Huron has the second largest annual frequency of SPB days with small interannual variation. The primary differences of the annual frequency of lake-to-lake (L2L) LE occurrences when compared with previous research were a greater variability in the L2L annual frequency of Superior-to-Michigan connections, greater frequency of Michigan-to-Huron connections, and less frequent occurrences for Superior-to-Huron and Michigan-to-Erie connections. © 2016 Royal Meteorological Society"
"57210379832;36967576800;48861632600;6701497419;","Mapping the reduction in gross primary productivity in subarctic birch forests due to insect outbreaks",2017,"10.5194/bg-14-1703-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016599211&doi=10.5194%2fbg-14-1703-2017&partnerID=40&md5=e7e213afa74aa81a4cacd96ca9682ccd","It is projected that forest disturbances, such as insect outbreaks, will have an increasingly negative impact on forests with a warmer climate. These disturbance events can have a substantial impact on forests' ability to absorb atmospheric CO2, and may even turn forests from carbon sinks into carbon sources; hence, it is important to develop methods both to monitor forest disturbances and to quantify the impact of these disturbance events on the carbon balance. In this study we present a method to monitor insect-induced defoliation in a subarctic birch forest in northern Sweden, and to quantify the impact of these outbreaks on gross primary productivity (GPP). Since frequent cloud cover in the study area requires data with high temporal resolution and limits the use of finer spatial resolution sensors such as Landsat, defoliation was mapped with remote sensing data from the MODIS sensor with 250m ×250m spatial resolution. The impact on GPP was estimated with a light use efficiency (LUE) model that was calibrated with GPP data obtained from eddy covariance (EC) measurements from 5 years with undisturbed birch forest and 1 year with insect-induced defoliation. Two methods were applied to estimate the impact on GPP: (1) applying a GPP reduction factor derived from EC measured GPP to estimate GPP loss, and (2) running a LUE model for both undisturbed and defoliated forest and deriving the differences in modelled GPP. In the study area of 100 km2 the results suggested a substantial setback to the carbon uptake: an average decrease in regional GPP over the three outbreak years (2004, 2012, and 2013) was estimated to 15±5 GgCyr-1 compared to the mean regional GPP of 40 ±12 GgCyr-1 for the 5years without defoliation, i.e. 38g%. In the most severe outbreak year (2012), 76% of the birch forests were defoliated, and annual regional GPP was merely 50% of GPP for years without disturbances. The study has generated valuable data on GPP reduction, and demonstrates a potential for mapping insect disturbance impact over extended areas. © Author(s) 2017."
"13403025600;8727832400;8557387300;7102615193;36796969000;34873296500;","Extension of summer climatic conditions into spring in the Western Mediterranean area",2017,"10.1002/joc.4824","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978737250&doi=10.1002%2fjoc.4824&partnerID=40&md5=5a95518ccaf5a4157d7f3b23a8df5fee","From a local point of view, in May/June, there is an important and positive 2 m temperature trend at Palma (Mallorca), which is simultaneous and highly correlated with a strong increase in the 500 hPa geopotential height. This study analyses this fact as well as the observed tendencies in a wider seasonal and geographical context. We confirm the particularly high correlation between 2 m temperature and 500 hPa geopotential during the warm months as opposed to the much weaker correlation in winter. This suggests that mechanisms for thermal changes act differently throughout the year in this region. Besides the direct radiative effect, warm season near-surface temperatures are linked to the presence of deep anticyclones, which effectively determine the northern edge of the Hadley cell. Accordingly, the strong warming trend in the area of Palma during the warm months of the year is purportedly related to the poleward extension of the Hadley cell. The fact that May/June shows the highest low-level temperature trend among all bi-monthly series is a common regional feature over a relatively wide area over the Western Mediterranean. Different geographical patterns emerge in other periods of the year. In July/August, the strongest low-level warming area drifts to the east-northeast, towards Ukraine and Russia. Coincidentally, the 500 hPa geopotential tendencies show a coherent pattern, with an intense positive trend ridge over the Western Mediterranean area in May/June, and a displacement of this ridge to the north-east in July/August. We show the connection between 500 hPa geopotential height and near-surface temperature by means of a multiple lineal regression that attributes half of the local temperature tendency in Palma to the intensification of a 500 hPa ridge centred over the Western Mediterranean and surroundings. © 2016 Royal Meteorological Society"
"24759735100;6602624799;7004887621;","Low-frequency variability and trends in centennial precipitation stations in southern South America",2017,"10.1002/joc.4810","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978086976&doi=10.1002%2fjoc.4810&partnerID=40&md5=3cef6455946535120359b8a1973beb2f","Southern South America (SSA), considered as the continental region south of 20°S, has experienced significant precipitation variability and trends in the last decades. This article uses monthly quality-controlled precipitation data from rainfall stations with continuous observations during at least 100 years to quantify long-term trends as well as interannual-to-centennial variability. Several statistical methods are applied to the data, primarily to detect jumps and look for changes due to relocation of the gauge stations, as well as to identify significant trends. Most of the regions have registered an increase in annual rainfall, largely attributable to changes in the warm season. On the other hand, during winter most stations in Argentina and Brazil do not have significant trends, although eastern Patagonia registered an increase in precipitation and Chile, a marked decrease in rainfall. In order to look into the physical mechanisms behind the observed variability, the changes in mean sea level pressure and precipitable water are quantified for different sub-periods. Also explored is the variability related to the Hadley cell width and strength over the region around SSA. Results show that the Hadley cell has shrunk and shifted towards the equator in winter over the area, which has caused an enhancement of the sinking motion over much of Argentina, Chile and Brazil, while likely increasing the baroclinicity (and associated precipitation) over Patagonia. In summer, the strength of the subsidence decreased and this was associated with an increase of the low-level moisture advection, favouring more rainfall. The observational evidence presented here suggests that the zonal asymmetry in the change of the Hadley cell position over SSA could be linked to the presence of the Andes Cordillera. © 2016 Royal Meteorological Society"
"57188742108;9043417100;36465124400;7006235542;","Microphysical sensitivity of coupled springtime Arctic stratocumulus to modelled primary ice over the ice pack, marginal ice, and ocean",2017,"10.5194/acp-17-4209-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016614828&doi=10.5194%2facp-17-4209-2017&partnerID=40&md5=7a489b71947045d50a187a0a37ff124c","This study uses large eddy simulations to test the sensitivity of single-layer mixed-phase stratocumulus to primary ice number concentrations in the European Arctic. Observations from the Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign are considered for comparison with cloud microphysics modelled using the Large Eddy Model (LEM, UK Met. Office). We find that cloud structure is very sensitive to ice number concentrations, Nice, and small increases can cause persisting mixed-phase clouds to glaciate and break up. Three key dependencies on Nice are identified from sensitivity simulations and comparisons with observations made over the sea ice pack, marginal ice zone (MIZ), and ocean. Over sea ice, we find deposition-condensation ice formation rates are overestimated, leading to cloud glaciation. When ice formation is limited to water-saturated conditions, we find microphysics comparable to aircraft observations over all surfaces considered. We show that warm supercooled (-13°C) mixed-phase clouds over the MIZ are simulated to reasonable accuracy when using both the DeMott et al.(2010) and Cooper(1986) primary ice nucleation parameterisations. Over the ocean, we find a strong sensitivity of Arctic stratus to Nice. The Cooper(1986) parameterisation performs poorly at the lower ambient temperatures, leading to a comparatively higher Nice (2.43L-1 at the cloud-top temperature, approximately-20°C) and cloud glaciation. A small decrease in the predicted Nice (2.07L-1 at-20°C), using the DeMott et al.(2010) parameterisation, causes mixed-phase conditions to persist for 24h over the ocean. However, this representation leads to the formation of convective structures which reduce the cloud liquid water through snow precipitation, promoting cloud break-up through a depleted liquid phase. Decreasing the Nice further (0.54L-1, using a relationship derived from ACCACIA observations) allows mixed-phase conditions to be maintained for at least 24h with more stability in the liquid and ice water paths. Sensitivity to Nice is also evident at low number concentrations, where 0.1 ×Nice predicted by the DeMott et al.(2010) parameterisation results in the formation of rainbands within the model; rainbands which also act to deplete the liquid water in the cloud and promote break-up. © 2017 The Author(s)."
"56963229300;7403364008;6603711967;","Parameterization-based uncertainty in future lightning flash density",2017,"10.1002/2017GL073017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016435077&doi=10.1002%2f2017GL073017&partnerID=40&md5=482060b8a081feae3131850228538460","In this study we implement eight lightning parameterizations in the Community Atmospheric Model (CAM5), evaluate the performance of the parameterizations in the present climate, and test the sensitivity of future lightning activity to the choice of parameterization. In the present day, the annual mean lightning flash densities in simulations constrained by reanalysis data show the highest spatial correlation to satellite observations for parameterizations based either on cloud top height (0.83) or cold cloud depth (0.80). Under future scenarios using representative concentration pathways, changes in global mean lightning flash density are highly sensitive to the parameterization chosen, with cloud top height schemes, a cold cloud depth scheme, and a scheme based on convective mass flux projecting large increases (36% to 45%), a mild increase (12.6%), and a decrease (−6.7%) in lightning flash density, respectively, under the RCP8.5 scenario, which causes a 3.4 K warming between 1996–2005 and 2079–2088. ©2017. American Geophysical Union. All Rights Reserved."
"7006128738;9942092200;57188592383;57188592125;6701714180;35766719400;","An automated method for the evaluation of the pointing accuracy of Sun-tracking devices",2017,"10.5194/amt-10-1181-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016145089&doi=10.5194%2famt-10-1181-2017&partnerID=40&md5=8444b092525adf7a1374aa7a9866e990","The accuracy of solar radiation measurements, for direct (DIR) and diffuse (DIF) radiation, depends significantly on the precision of the operational Sun-tracking device. Thus, rigid targets for instrument performance and operation have been specified for international monitoring networks, e.g., the Baseline Surface Radiation Network (BSRN) operating under the auspices of the World Climate Research Program (WCRP). Sun-tracking devices that fulfill these accuracy requirements are available from various instrument manufacturers; however, none of the commercially available systems comprise an automatic accuracy control system allowing platform operators to independently validate the pointing accuracy of Sun-tracking sensors during operation. Here we present KSO-STREAMS (KSO-SunTRackEr Accuracy Monitoring System), a fully automated, system-independent, and cost-effective system for evaluating the pointing accuracy of Sun-tracking devices. We detail the monitoring system setup, its design and specifications, and the results from its application to the Sun-tracking system operated at the Kanzelhöhe Observatory (KSO) Austrian radiation monitoring network (ARAD) site. The results from an evaluation campaign from March to June 2015 show that the tracking accuracy of the device operated at KSO lies within BSRN specifications (i.e., 0.1° tracking accuracy) for the vast majority of observations (99.8 %). The evaluation of manufacturer-specified active-tracking accuracies (0.02°), during periods with direct solar radiation exceeding 300 W m-2, shows that these are satisfied in 72.9 % of observations. Tracking accuracies are highest during clear-sky conditions and on days where prevailing clear-sky conditions are interrupted by frontal movement; in these cases, we obtain the complete fulfillment of BSRN requirements and 76.4 % of observations within manufacturer-specified active-tracking accuracies. Limitations to tracking surveillance arise during overcast conditions and periods of partial solar-limb coverage by clouds. On days with variable cloud cover, 78.1 % (99.9 %) of observations meet active-tracking (BSRN) accuracy requirements while for days with prevailing overcast conditions these numbers reduce to 64.3 % (99.5 %). © Author(s) 2017."
"57193694921;7004384155;36945003900;","Upper tropospheric cloud systems derived from IR sounders: Properties of cirrus anvils in the tropics",2017,"10.5194/acp-17-3845-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016008380&doi=10.5194%2facp-17-3845-2017&partnerID=40&md5=115657b00a20e61b692fa21a2c38d054","Representing about 30g% of the Earth's total cloud cover, upper tropospheric clouds play a crucial role in the climate system by modulating the Earth's energy budget and heat transport. When originating from convection, they often form organized systems. The high spectral resolution of the Atmospheric Infrared Sounder (AIRS) allows reliable cirrus identification, both from day and nighttime observations. Tropical upper tropospheric cloud systems have been analyzed by using a spatial composite technique on the retrieved cloud pressure of AIRS data. Cloud emissivity is used to distinguish convective core, cirrus and thin cirrus anvil within these systems. A comparison with simultaneous precipitation data from the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E) shows that, for tropical upper tropospheric clouds, a cloud emissivity close to 1 is strongly linked to a high rain rate, leading to a proxy to identify convective cores. Combining AIRS cloud data with this cloud system approach, using physical variables, provides a new opportunity to relate the properties of the anvils, including also the thinner cirrus, to the convective cores. It also distinguishes convective cloud systems from isolated cirrus systems. Deep convective cloud systems, covering 15g% of the tropics, are further distinguished into single-core and multi-core systems. Though AIRS samples the tropics only twice per day, the evolution of longer-living convective systems can be still statistically captured, and we were able to select relatively mature single-core convective systems by using the fraction of convective core area within the cloud systems as a proxy for maturity. For these systems, we have demonstrated that the physical properties of the anvils are related to convective depth, indicated by the minimum retrieved cloud temperature within the convective core. Our analyses show that the size of the systems does in general increase with convective depth, though for similar convective depth oceanic convective cloud systems are slightly larger than continental ones, in agreement with other observations. In addition, our data reveal for the first time that the fraction of thin cirrus over the total anvil area increases with the convective depth similarly for oceanic and continental convective systems. This has implications for the radiative feedbacks of anvils on convection which will be more closely studied in the future. © Author(s) 2017. CC Attribution 3.0 License."
"23485410200;6603821988;7004966070;23968109800;","The Met Office HadGEM3-ES chemistry-climate model: Evaluation of stratospheric dynamics and its impact on ozone",2017,"10.5194/gmd-10-1209-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015999768&doi=10.5194%2fgmd-10-1209-2017&partnerID=40&md5=f266fed7f20412be4c7cddb1e5d7c6e7","Free-running and nudged versions of a Met Office chemistry-climate model are evaluated and used to investigate the impact of dynamics versus transport and chemistry within the model on the simulated evolution of stratospheric ozone. Metrics of the dynamical processes relevant for simulating stratospheric ozone are calculated, and the free-running model is found to outperform the previous model version in 10 of the 14 metrics. In particular, large biases in stratospheric transport and tropical tropopause temperature, which existed in the previous model version, are substantially reduced, making the current model more suitable for the simulation of stratospheric ozone. The spatial structure of the ozone hole, the area of polar stratospheric clouds, and the increased ozone concentrations in the Northern Hemisphere winter stratosphere following sudden stratospheric warmings, were all found to be sensitive to the accuracy of the dynamics and were better simulated in the nudged model than in the free-running model. Whilst nudging can, in general, provide a useful tool for removing the influence of dynamical biases from the evolution of chemical fields, this study shows that issues can remain in the climatology of nudged models. Significant biases in stratospheric vertical velocities, age of air, water vapour, and total column ozone still exist in the Met Office nudged model. Further, these can lead to biases in the downward flux of ozone into the troposphere. © Author(s) 2017. CC Attribution 3.0 License."
"56797942500;11339401400;55965624000;57193695551;55976582900;15019752400;6701413579;7006084942;7005219614;","Sensitivity of transatlantic dust transport to chemical aging and related atmospheric processes",2017,"10.5194/acp-17-3799-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015872714&doi=10.5194%2facp-17-3799-2017&partnerID=40&md5=ec92915445881a20c1cdd3bdeefba8fc","We present a sensitivity study on transatlantic dust transport, a process which has many implications for the atmosphere, the ocean and the climate. We investigate the impact of key processes that control the dust outflow, i.e., the emission flux, convection schemes and the chemical aging of mineral dust, by using the EMAC model following Abdelkader et al. (2015). To characterize the dust outflow over the Atlantic Ocean, we distinguish two geographic zones: (i) dust interactions within the Intertropical Convergence Zone (ITCZ), or the dust-ITCZ interaction zone (DIZ), and (ii) the adjacent dust transport over the Atlantic Ocean (DTA) zone. In the latter zone, the dust loading shows a steep and linear gradient westward over the Atlantic Ocean since particle sedimentation is the dominant removal process, whereas in the DIZ zone aerosol-cloud interactions, wet deposition and scavenging processes determine the extent of the dust outflow. Generally, the EMAC simulated dust compares well with CALIPSO observations; however, our reference model configuration tends to overestimate the dust extinction at a lower elevation and underestimates it at a higher elevation. The aerosol optical depth (AOD) over the Caribbean responds to the dust emission flux only when the emitted dust mass is significantly increased over the source region in Africa by a factor of 10. These findings point to the dominant role of dust removal (especially wet deposition) in transatlantic dust transport. Experiments with different convection schemes have indeed revealed that the transatlantic dust transport is more sensitive to the convection scheme than to the dust emission flux parameterization. To study the impact of dust chemical aging, we focus on a major dust outflow in July 2009. We use the calcium cation as a proxy for the overall chemical reactive dust fraction and consider the uptake of major inorganic acids (i.e., H2SO4, HNO3 and HCl) and their anions, i.e., sulfate (SO42-), bisulfate (HSO4-), nitrate (NO3-) and chloride (Cl-), on the surface of mineral particles. The subsequent neutralization reactions with the calcium cation form various salt compounds that cause the uptake of water vapor from the atmosphere, i.e., through the chemical aging of dust particles leading to an increase of 0.15 in the AOD under subsaturated conditions (July 2009 monthly mean). As a result of the radiative feedback on surface winds, dust emissions increased regionally. On the other hand, the aged dust particles, compared to the non-aged particles, are more efficiently removed by both wet and dry deposition due to the increased hygroscopicity and particle size (mainly due to water uptake). The enhanced removal of aged particles decreases the dust burden and lifetime, which indirectly reduces the dust AOD by 0.05 (monthly mean). Both processes can be significant (major dust outflow, July 2009), but the net effect depends on the region and level of dust chemical aging. © The Author(s) 2017."
"9843695000;6603287639;7004272801;55437944700;9233091000;7102578937;6701727687;24460392200;7004600486;11439762000;7102242175;56102017200;7004419968;35433083100;35550043200;57205479513;7102807964;6603516536;7004168515;7202489497;24074877700;","The SPARC water vapour assessment II: Comparison of annual, semi-annual and quasi-biennial variations in stratospheric and lower mesospheric water vapour observed from satellites",2017,"10.5194/amt-10-1111-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015674234&doi=10.5194%2famt-10-1111-2017&partnerID=40&md5=c11e2a1148a0aeb07b9e99be8d68572e","In the framework of the second SPARC (Stratosphere-troposphere Processes And their Role in Climate) water vapour assessment (WAVAS-II), the amplitudes and phases of the annual, semi-annual and quasi-biennial variation in stratospheric and lower mesospheric water were compared using 30 data sets from 13 different satellite instruments. These comparisons aimed to provide a comprehensive overview of the typical uncertainties in the observational database which can be considered in subsequent observational and modelling studies. For the amplitudes, a good agreement of their latitude and altitude distribution was found. Quantitatively there were differences in particular at high latitudes, close to the tropopause and in the lower mesosphere. In these regions, the standard deviation over all data sets typically exceeded 0.2 ppmv for the annual variation and 0.1 ppmv for the semi-annual and quasi-biennial variation. For the phase, larger differences between the data sets were found in the lower mesosphere. Generally the smallest phase uncertainties can be observed in regions where the amplitude of the variability is large. The standard deviations of the phases for all data sets were typically smaller than a month for the annual and semi-annual variation and smaller than 5 months for the quasi-biennial variation. The amplitude and phase differences among the data sets are caused by a combination of factors. In general, differences in the temporal variation of systematic errors and in the observational sampling play a dominant role. In addition, differences in the vertical resolution of the data, the considered time periods and influences of clouds, aerosols as well as non-local thermodynamic equilibrium (NLTE) effects cause differences between the individual data sets. © 2017 Author(s)."
"57193647489;6701382296;","Wintertime enhancements of sea salt aerosol in polar regions consistent with a sea ice source from blowing snow",2017,"10.5194/acp-17-3699-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015453801&doi=10.5194%2facp-17-3699-2017&partnerID=40&md5=673b320f45885eaed9d7415a1407f570","Sea salt aerosols (SSA) are generated via air bubbles bursting at the ocean surface as well as by wind mobilization of saline snow and frost flowers over sea-ice-covered areas. The relative magnitude of these sources remains poorly constrained over polar regions, affecting our ability to predict their impact on halogen chemistry, cloud formation, and climate. We implement a blowing snow and a frost flower emission scheme in the GEOS-Chem global chemical transport model, which we validate against multiyear (2001-2008) in situ observations of SSA mass concentrations at three sites in the Arctic, two sites in coastal Antarctica, and from the 2008 ICEALOT cruise in the Arctic. A simulation including only open ocean emissions underestimates SSA mass concentrations by factors of 2-10 during winter-spring for all ground-based and ship-based observations. When blowing snow emissions are added, the model is able to reproduce observed wintertime SSA concentrations, with the model bias decreasing from a range of -80 to -34g% for the open ocean simulation to -2 to +9g% for the simulation with blowing snow emissions. We find that the frost flower parameterization cannot fully explain the high wintertime concentrations and displays a seasonal cycle decreasing too rapidly in early spring. Furthermore, the high day-to-day variability of observed SSA is better reproduced by the blowing snow parameterization. Over the Arctic (>60°N) (Antarctic, >60° S), we calculate that submicron SSA emissions from blowing snow account for 1.0gTggyr-1 (2.5gTggyr-1), while frost flower emissions lead to 0.21gTggyr-1 (0.25gTggyr-1) compared to 0.78gTggyr-1 (1.0gTggyr-1) from the open ocean. Blowing snow emissions are largest in regions where persistent strong winds occur over sea ice (east of Greenland, over the central Arctic, Beaufort Sea, and the Ross and Weddell seas). In contrast, frost flower emissions are largest where cold air temperatures and open leads are co-located (over the Canadian Arctic Archipelago, coastal regions of Siberia, and off the Ross and Ronne ice shelves). Overall, in situ observations of mass concentrations of SSA suggest that blowing snow is likely to be the dominant SSA source during winter, with frost flowers playing a much smaller role. © Author(s) 2017."
"57204123494;57139379600;57189073273;56041901600;57211336354;","Fast responses of climate system to carbon dioxide, aerosols and sulfate aerosols without the mediation of SST in the CMIP5",2017,"10.1002/joc.4763","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969963020&doi=10.1002%2fjoc.4763&partnerID=40&md5=91943272fb205b742f71d179818b07da","In this study, fast climate system responses to CO2, aerosols and sulfate aerosols are studied based on simulations of Coupled Model Inter-comparison Project Phase 5 (CMIP5) atmospheric models. We demonstrate that the fast climate adjustments caused by CO2 forcing lead to decreases in global annual mean cloud fractions, evaporation and precipitation and to increases in the global annual mean net radiative forcing and atmospheric water vapour content. The inhibition of rainfall is primarily caused by the reduced oceanic precipitation. Regionally, Africa, South Asia, East Asia and Australia exhibit pronounced increases in rainfall, which are presumably attributed to the strengthened summer monsoon caused by the increased land–sea thermal contrast. Aerosols and sulfate aerosols exhibit only a slight effect on the global hydrological cycle before global surface temperature changes. However, by affecting the land–sea thermal contrast, they can have profound effects on regional-scale hydrological cycles, such as those over southern Africa, South Asia and East Asia in the boreal summer. Moreover, the cloud fast feedback under the aerosol forcing is highly associated with the way of dealing with aerosols in the atmospheric model. © 2016 Royal Meteorological Society"
"57191033521;8404544300;36560691800;55547119523;55480654300;8942524900;36766707000;7006204597;22953153500;10739566100;7004715270;55683314900;7006708207;21834810800;7004469744;","Contribution of feldspar and marine organic aerosols to global ice nucleating particle concentrations",2017,"10.5194/acp-17-3637-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015640914&doi=10.5194%2facp-17-3637-2017&partnerID=40&md5=84b338c15f9c1bba6250e75d95b02c13","Ice-nucleating particles (INPs) are known to affect the amount of ice in mixed-phase clouds, thereby influencing many of their properties. The atmospheric INP concentration changes by orders of magnitude from terrestrial to marine environments, which typically contain much lower concentrations. Many modelling studies use parameterizations for heterogeneous ice nucleation and cloud ice processes that do not account for this difference because they were developed based on INP measurements made predominantly in terrestrial environments without considering the aerosol composition. Errors in the assumed INP concentration will influence the simulated amount of ice in mixed-phase clouds, leading to errors in top-of-atmosphere radiative flux and ultimately the climate sensitivity of the model. Here we develop a global model of INP concentrations relevant for mixed-phase clouds based on laboratory and field measurements of ice nucleation by K-feldspar (an ice-active component of desert dust) and marine organic aerosols (from sea spray). The simulated global distribution of INP concentrations based on these two species agrees much better with currently available ambient measurements than when INP concentrations are assumed to depend only on temperature or particle size. Underestimation of INP concentrations in some terrestrial locations may be due to the neglect of INPs from other terrestrial sources. Our model indicates that, on a monthly average basis, desert dusts dominate the contribution to the INP population over much of the world, but marine organics become increasingly important over remote oceans and they dominate over the Southern Ocean. However, day-to-day variability is important. Because desert dust aerosol tends to be sporadic, marine organic aerosols dominate the INP population on many days per month over much of the mid- and high-latitude Northern Hemisphere. This study advances our understanding of which aerosol species need to be included in order to adequately describe the global and regional distribution of INPs in models, which will guide ice nucleation researchers on where to focus future laboratory and field work. © Author(s) 2017."
"26424374700;26424299000;35767429400;","Effects of cloud and humidity on atmospheric extinction coefficient derived from visual range observations in Iranian major airports",2017,"10.1002/joc.4791","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973525489&doi=10.1002%2fjoc.4791&partnerID=40&md5=0cc75fdeb23fbebbe96f87fdc4627137","Visibility impairment, one of the restricting phenomena for aviation, results from light scattering and absorption. In this study, the historical visibility database for the period of 1981–2010 is used to obtain extinction coefficient according to the Koschmieder theory in the four busiest airports in Iran, including Tehran-Mehrabad, Mashhad, Shiraz and Isfahan. The long-term trend of extinction coefficient and its seasonal variations are investigated using 10th and 90th percentiles of extinction data to show the visual range in each airport. Correlation of the long-term visibility trend with relative humidity (RH) and cloudiness is also examined. The comparison of seasonal mean extinctions shows the noticeable effect of local climate. The highest extinction coefficient value in each airport is seen during winter, while the lowest value occurs in summer. The seasonal mean extinction coefficient level in winter is about 0.1 km−1 higher than those of the other seasons. This is likely due to pollutants trapped by the stagnant cold air that partly obstruct visibility and increase the extinction in wintertime. There is not an outstanding variation of the tenth percentile of the extinction coefficient in the four airports. The low variation may relate to the definition of the upper threshold in visibility. Analysis shows that there is a positive correlation between extinction and humidity in all the airports that indicates the increase of scattering by hygroscopic particles with increasing humidity, such effect would be accentuated in high RH. The same result is seen for different percentages of cloudiness. To minimize the effects of humidity and cloudiness on the long-term visibility trend, the days with the relative humidity values more than 70% and cloudiness of more than 5/8 of the sky are removed from the visibility trend analysis. The trends of the screened days are nearly parallel to the trends of raw data, but with a slight difference in each airport. The overall filtered long-term trends show the increase of extinction coefficient at all the airports that emphasize the effect of pollution on the trend of light extinction within the whole period of this study. Eliminating the meteorological factors from the raw data does not change the overall increasing trend of extinction at Tehran and Isfahan airports. It suggests that the changes in air quality are responsible for the long-term visibility degradation at these two stations that are located in the two most highly industrialized and polluted cities in Iran. © 2016 Royal Meteorological Society"
"57193696275;57204307377;56304460900;7003495982;57199451838;","Surface Variability of Short-wavelength Radiation and Temperature on Exoplanets around M Dwarfs",2017,"10.3847/2041-8213/aa62fc","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015813554&doi=10.3847%2f2041-8213%2faa62fc&partnerID=40&md5=7b66038670b3a72bc2a068a6dd5607ae","It is a common practice to use 3D General Circulation Models (GCM) with spatial resolution of a few hundred kilometers to simulate the climate of Earth-like exoplanets. The enhanced albedo effect of clouds is especially important for exoplanets in the habitable zones around M dwarfs that likely have fixed substellar regions and substantial cloud coverage. Here, we carry out mesoscale model simulations with 3 km spatial resolution driven by the initial and boundary conditions in a 3D GCM and find that it could significantly underestimate the spatial variability of both the incident short-wavelength radiation and the temperature at planet surface. Our findings suggest that mesoscale models with cloud-resolving capability be considered for future studies of exoplanet climate. © 2017. The American Astronomical Society. All rights reserved."
"56677549900;6701412834;9233163800;6602184993;","Simultaneous retrieval of water vapour, temperature and cirrus clouds properties from measurements of far infrared spectral radiance over the Antarctic Plateau",2017,"10.5194/amt-10-825-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015054780&doi=10.5194%2famt-10-825-2017&partnerID=40&md5=2b613170b600e8d2f232799a41d41f00","The possibility separating the contributions of the atmospheric state and ice clouds by using spectral infrared measurements is a fundamental step to quantifying the cloud effect in climate models. A simultaneous retrieval of cloud and atmospheric parameters from infrared wideband spectra will allow the disentanglement of the spectral interference between these variables. In this paper, we describe the development of a code for the simultaneous retrieval of atmospheric state and ice cloud parameters, and its application to the analysis of the spectral measurements acquired by the Radiation Explorer in the Far Infrared-Prototype for Applications and Development (REFIR-PAD) spectroradiometer, which has been in operation at Concordia Station on the Antarctic Plateau since 2012. The code performs the retrieval with a computational time that is comparable with the instrument acquisition time. Water vapour and temperature profiles and the cloud optical and microphysical properties, such as the generalised effective diameter and the ice water path, are retrieved by exploiting the 230-980ĝ€cmĝ'1 spectral band. To simulate atmospheric radiative transfer, the Line-By-Line Radiative Transfer Model (LBLRTM) has been integrated with a specifically developed subroutine based on the <i>Î</i>-Eddington two-stream approximation, whereas the single-scattering properties of cirrus clouds have been derived from a database for hexagonal column habits. In order to detect ice clouds, a backscattering and depolarisation lidar, co-located with REFIR-PAD has been used, allowing us to infer the position and the cloud thickness to be used in the retrieval. A climatology of the vertical profiles of water vapour and temperature has been performed by using the daily radiosounding available at the station at 12:00ĝ€UTC. The climatology has been used to build an a priori profile correlation to constrain the fitting procedure. An optimal estimation method with the Levenberg-Marquardt approach has been used to perform the retrieval. In most cases, the retrieved humidity and temperature profiles show a good agreement with the radiosoundings, demonstrating that the simultaneous retrieval of the atmospheric state is not biased by the presence of cirrus clouds. Finally, the retrieved cloud parameters allow us to study the relationships between cloud temperature and optical depth and between effective particle diameter and ice water content. These relationships are similar to the statistical correlations measured on the Antarctic coast at Dumont d'Urville and in the Arctic region. © 2017 Author(s)."
"35867442600;35810775100;7004469744;12806941900;9536598800;7103016965;","Spatial and temporal CCN variations in convection-permitting aerosol microphysics simulations in an idealised marine tropical domain",2017,"10.5194/acp-17-3371-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015183449&doi=10.5194%2facp-17-3371-2017&partnerID=40&md5=657626b9dd7bf84cca0168d2dfde8e35","A convection-permitting limited area model with periodic lateral boundary conditions and prognostic aerosol microphysics is applied to investigate how concentrations of cloud condensation nuclei (CCN) in the marine boundary layer are affected by high-resolution dynamical and thermodynamic fields. The high-resolution aerosol microphysics-dynamics model, which resolves differential particle growth and aerosol composition across the particle size range, is applied to a domain designed to match approximately a single grid square of a climate model. We find that, during strongly convective conditions with high wind-speed conditions, CCN concentrations vary by more than a factor of 8 across the domain (5-95th percentile range), a factor of ∼3 at more moderate wind speed. One reason for these large sub-climate-grid-scale variations in CCN is that emissions of sea salt and dimethyl sulfide (DMS) are much higher when spatial and temporal wind-speed fluctuations become resolved at this convection-permitting resolution (making peak wind speeds higher). By analysing how the model evolves during spin-up, we gain new insight into the way primary sea salt and secondary sulfate particles contribute to the overall CCN variance in these realistic conditions, find a marked difference in the variability of super-micron and sub-micron CCN. Whereas the super-micron CCN are highly variable, dominated by strongly fluctuating sea spray emitted, the sub-micron CCN tend to be steadier, mainly produced on longer timescales following growth after new particle formation in the free troposphere, with fluctuations inherently buffered by the fact that coagulation is faster at higher particle concentrations. We also find that sub-micron CCN are less variable in particle size, the accumulation-mode mean size varying by ∼20% (0.101 to 0.123μm diameter) compared to ∼35 % (0.75 to 1.10μm diameter) for coarse-mode particles at this resolution. We explore how the CCN variability changes in the vertical and at different points in the spin-up, showing how CCN concentrations are introduced both by the emissions close to the surface and at higher altitudes during strong wind-speed conditions associated to the intense convective period. We also explore how the non-linear variation of sea-salt emissions with wind speed propagates into variations in sea-salt mass mixing ratio and CCN concentrations, finding less variation in the latter two quantities due to the longer transport timescales inherent with finer CCN, which sediment more slowly. The complex mix of sources and diverse community of processes involved makes sub-grid parameterisation of CCN variations difficult. However, the results presented here illustrate the limitations of predictions with large-scale models and the high-resolution aerosol microphysics-dynamics modelling system shows promise for future studies where the aerosol variations will propagate through to modified cloud microphysical evolution. © 2017 The Author(s)."
"57193574176;7004174939;7003478309;18134565600;16834406100;36169987900;7201953443;8643810200;37037211400;24578264300;","Retrievals of aerosol optical and microphysical properties from Imaging Polar Nephelometer scattering measurements",2017,"10.5194/amt-10-811-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015042187&doi=10.5194%2famt-10-811-2017&partnerID=40&md5=47cf95f9194bdb76267b3447809fce2f","A method for the retrieval of aerosol optical and microphysical properties from in situ light-scattering measurements is presented and the results are compared with existing measurement techniques. The Generalized Retrieval of Aerosol and Surface Properties (GRASP) is applied to airborne and laboratory measurements made by a novel polar nephelometer. This instrument, the Polarized Imaging Nephelometer (PI-Neph), is capable of making high-accuracy field measurements of phase function and degree of linear polarization, at three visible wavelengths, over a wide angular range of 3 to 177°. The resulting retrieval produces particle size distributions (PSDs) that agree, within experimental error, with measurements made by commercial optical particle counters (OPCs). Additionally, the retrieved real part of the refractive index is generally found to be within the predicted error of 0.02 from the expected values for three species of humidified salt particles, with a refractive index that is well established. The airborne measurements used in this work were made aboard the NASA DC-8 aircraft during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field campaign, and the inversion of this data represents the first aerosol retrievals of airborne polar nephelometer data. The results provide confidence in the real refractive index product, as well as in the retrieval's ability to accurately determine PSD, without assumptions about refractive index that are required by the majority of OPCs. © The Author(s) 2017."
"54410286000;57189225001;25648263800;7103156669;10141225800;56709590600;7801401670;6602115068;","An exploratory study on the aerosol height retrieval from OMI measurements of the 477 nmO2 O2 spectral band using a neural network approach",2017,"10.5194/amt-10-783-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015027388&doi=10.5194%2famt-10-783-2017&partnerID=40&md5=7fd0f82720abce04155554f29b248ce1","This paper presents an exploratory study on the aerosol layer height (ALH) retrieval from the OMI 477nm O2 O2 spectral band. We have developed algorithms based on the multilayer perceptron (MLP) neural network (NN) approach and applied them to 3-year (2005-2007) OMI cloud-free scenes over north-east Asia, collocated with MODIS Aqua aerosol product. In addition to the importance of aerosol altitude for climate and air quality objectives, our long-term motivation is to evaluate the possibility of retrieving ALH for potential future improvements of trace gas retrievals (e.g. NO2, HCHO, SO2) from UV-visible air quality satellite measurements over scenes including high aerosol concentrations. This study presents a first step of this long-term objective and evaluates, from a statistic point of view, an ensemble of OMI ALH retrievals over a long time period of 3 years covering a large industrialized continental region. This ALH retrieval relies on the analysis of the O2 O2 slant column density (SCD) and requires an accurate knowledge of the aerosol optical thickness,. Using MODIS Aqua(550nm) as a prior information, absolute seasonal differences between the LIdar climatology of vertical Aerosol Structure for space-based lidar simulation (LIVAS) and average OMI ALH, over scenes with MODIS(550nm) ≥ 1. 0, are in the range of 260-800m (assuming single scattering albedo 0 Combining double low line 0. 95) and 180-310m (assuming 0 Combining double low line 0. 9). OMI ALH retrievals depend on the assumed aerosol single scattering albedo (sensitivity up to 660 m) and the chosen surface albedo (variation less than 200 m between OMLER and MODIS black-sky albedo). Scenes with ≤ 0. 5 are expected to show too large biases due to the little impact of particles on the O2 O2 SCD changes. In addition, NN algorithms also enable aerosol optical thickness retrieval by exploring the OMI reflectance in the continuum. Comparisons with collocated MODIS Aqua show agreements between 0. 02 ± 0. 45 and 0. 18 ± g 0. 24, depending on the season. Improvements may be obtained from a better knowledge of the surface albedo and higher accuracy of the aerosol model. Following the previous work over ocean of Park et al.(2016), our study shows the first encouraging aerosol layer height retrieval results over land from satellite observations of the 477 nm O2 gO2 absorption spectral band. © 2017 Author(s)."
"57193528525;55711536900;7004115874;6603206037;","Characteristics of convective snow bands along the Swedish east coast",2017,"10.5194/esd-8-163-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014603521&doi=10.5194%2fesd-8-163-2017&partnerID=40&md5=245d4fde2a938d07c24151fb038b1f21","Convective snow bands develop in response to a cold air outbreak from the continent or the frozen sea over the open water surface of lakes or seas. The comparatively warm water body triggers shallow convection due to increased heat and moisture fluxes. Strong winds can align with this convection into wind-parallel cloud bands, which appear stationary as the wind direction remains consistent for the time period of the snow band event, delivering enduring snow precipitation at the approaching coast. The statistical analysis of a dataset from an 11-year high-resolution atmospheric regional climate model (RCA4) indicated 4 to 7 days a year of moderate to highly favourable conditions for the development of convective snow bands in the Baltic Sea region. The heaviest and most frequent lake effect snow was affecting the regions of Gävle and Västervik (along the Swedish east coast) as well as Gdansk (along the Polish coast). However, the hourly precipitation rate is often higher in Gävle than in the Västervik region. Two case studies comparing five different RCA4 model setups have shown that the Rossby Centre atmospheric regional climate model RCA4 provides a superior representation of the sea surface with more accurate sea surface temperature (SST) values when coupled to the ice-ocean model NEMO as opposed to the forcing by the ERA-40 reanalysis data. The refinement of the resolution of the atmospheric model component leads, especially in the horizontal direction, to significant improvement in the representation of the mesoscale circulation process as well as the local precipitation rate and area by the model. © Author(s) 2017."
"23105886000;7403494719;7005209721;57215879246;57190282154;37014635200;","Incorporating Autonomous Sensors and Climate Modeling to Gain Insight into Seasonal Hydrometeorological Processes within a Tropical Glacierized Valley",2017,"10.1080/24694452.2016.1232615","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992152214&doi=10.1080%2f24694452.2016.1232615&partnerID=40&md5=6e0497cfc64a28e37ce6b33bbf6bfb5b","Peru is facing imminent water resource issues as glaciers retreat and demand for water increases, yet limited observations and model resolution hamper understanding of hydrometerological processes on local to regional scales. Much of current global and regional climate studies neglect the meteorological forcing of lapse rates (LRs) and valley and slope wind dynamics on critical components of the Peruvian Andes' water cycle, and herein we emphasize the wet season. In 2004 and 2005 we installed an autonomous sensor network (ASN) within the glacierized Llanganuco Valley, Cordillera Blanca (9° S), consisting of discrete, cost-effective, automatic temperature loggers located along the valley axis and anchored by two automatic weather stations. Comparisons of these embedded hydrometeorological measurements from the ASN and climate modeling by dynamical downscaling using the Weather Research and Forecasting model elucidate distinct diurnal and seasonal characteristics of the mountain wind regime and LRs. Wind, temperature, humidity, and cloud simulations suggest that thermally driven up-valley and slope winds converging with easterly flow aloft enhance late afternoon and evening cloud development, which helps explain nocturnal wet season precipitation maxima measured by the ASN. Furthermore, the extreme diurnal variability of along-valley-axis LR and valley wind detected from ground observations and confirmed by dynamical downscaling demonstrate the importance of realistic scale parameterizations of the atmospheric boundary layer to improve regional climate model projections in mountainous regions. © 2017 by American Association of Geographers."
"56610839600;55965230500;57190191041;57193230168;","Time-series cloud noise mapping and reduction algorithm for improved vegetation and drought monitoring",2017,"10.1080/15481603.2017.1286726","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011928385&doi=10.1080%2f15481603.2017.1286726&partnerID=40&md5=1123c42fe3d6ce51f918f983b8f6b539","Moderate Resolution Imaging Spectro-radiometer (MODIS) time-series Normalized Differential Vegetation Index (NDVI) products are regularly used for vegetation monitoring missions and climate change analysis. However, satellite observation is affected by the atmospheric condition, cloud state and shadows introducing noise in the data. MODIS state flag helps in understanding pixel quality but overestimates the noise and hence its usability requires further scrutiny. This study has analyzed MODIS MOD09A1 annual data set over Sri Lanka. The study presents a simple and effective noise mapping method which integrates four state flag parameters (i.e. cloud state, cloud shadow, cirrus detected, and internal cloud algorithm flag) to estimate Cloud Possibility Index (CPI). Usability of CPI is analyzed along with NDVI for noise elimination. Then the gaps generated due to noise elimination are reconstructed and performance of the reconstruction model is assessed over simulated data with five different levels of random gaps (10–50%) and four different statistical measures (i.e. Root mean square error, mean absolute error, mean bias error, and mean absolute percentage error). The sample-based analysis over homogeneous and heterogeneous pixels have revealed that CPI-based noise elimination has increased the detection accuracy of number of growing cycle from 45–60% to 85–95% in vegetated regions. The study cautions that usage of time-series NDVI data without proper cloud correction mechanism would result in wrong estimation about spatial distribution and intensity of drought, and in our study 50% of area is wrongly reported to be under drought though there was no major drought in 2014. © 2017 Informa UK Limited, trading as Taylor & Francis Group."
"14631111100;6506703348;35578922100;56668704400;35584010200;56427880900;57192942594;57192940228;57192937668;57192940254;56921163600;57192939169;57192941029;36473630000;55241167300;","Characteristics of Precipitating Storms in Glacierized Tropical Andean Cordilleras of Peru and Bolivia",2017,"10.1080/24694452.2016.1260439","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009259804&doi=10.1080%2f24694452.2016.1260439&partnerID=40&md5=77de4f8ccc8dbd9c69bd6de218fbd971","Precipitation variability in tropical high mountains is a fundamental yet poorly understood factor influencing local climatic expression and a variety of environmental processes, including glacier behavior and water resources. Precipitation type, diurnality, frequency, and amount influence hydrological runoff, surface albedo, and soil moisture, whereas cloud cover associated with precipitation events reduces solar irradiance at the surface. Considerable uncertainty remains in the multiscale atmospheric processes influencing precipitation patterns and their associated regional variability in the tropical Andes—particularly related to precipitation phase, timing, and vertical structure. Using data from a variety of sources—including new citizen science precipitation stations; new high-elevation comprehensive precipitation monitoring stations at Chacaltaya, Bolivia, and the Quelccaya Ice Cap, Peru; and a vertically pointing Micro Rain Radar—this article synthesizes findings from interdisciplinary research activities in the Cordillera Real of Bolivia and the Cordillera Vilcanota of Peru related to the following two research questions: (1) How do the temporal patterns, moisture source regions, and El Niño-Southern Oscillation relationships with precipitation occurrence vary? (2) What is the vertical structure (e.g., reflectivity, Doppler velocity, melting layer heights) of tropical Andean precipitation and how does it evolve temporally? Results indicate that much of the heavy precipitation occurs at night, is stratiform rather than convective in structure, and is associated with Amazonian moisture influx from the north and northwest. Improving scientific understanding of tropical Andean precipitation is of considerable importance to assessing climate variability and change, glacier behavior, hydrology, agriculture, ecosystems, and paleoclimatic reconstructions. © 2017 by American Association of Geographers."
"57112070700;56014511300;56471281900;","On the role of the stratiform cloud scheme in the inter-model spread of cloud feedback",2017,"10.1002/2016MS000846","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013020770&doi=10.1002%2f2016MS000846&partnerID=40&md5=f486f9b420f7330af03997d00c2fb851","This study explores the role of the stratiform cloud scheme in the inter-model spread of cloud feedback. Six diagnostic cloud schemes used in various CMIP (Coupled Model Intercomparison Experiment] climate models are implemented (at low and midlevels) into two testbed climate models, and the impacts on cloud feedback are investigated. Results suggest that the choice of stratiform cloud scheme may contribute up to roughly half of the intermodel spread of cloud radiative responses in stratocumulus (Sc) regions, and may determine or favor a given sign of the feedback there. Cloud schemes assuming a probability density function for total water content consistently predict a positive feedback in Sc regions in our experiments. A large negative feedback in Sc regions is obtained only with schemes that consider variables other than relative humidity (e.g., stability). The stratiform cloud scheme also significantly affects cloud feedback at the scale of the tropics and at global scale. Results are slightly less consistent for tropical means, likely indicating coupling with other boundary layer processes such as convective mixing. © 2017. The Authors."
"56909327200;7401836526;36097134700;55351266200;","Large-eddy simulation of subtropical cloud-topped boundary layers: 2. Cloud response to climate change",2017,"10.1002/2016MS000804","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010723113&doi=10.1002%2f2016MS000804&partnerID=40&md5=2b009944619031b192274fb0ae5a1321","How subtropical marine boundary layer (MBL) clouds respond to warming is investigated using large-eddy simulations (LES) of a wide range of warmer climates, with CO2 concentrations elevated by factors 2–16. In LES coupled to a slab ocean with interactive sea surface temperatures (SST), the surface latent heat flux (LHF) is constrained by the surface energy balance and only strengthens modestly under warming. Consequently, the MBL in warmer climates is shallower than in corresponding fixed-SST LES, in which LHF strengthens excessively and the MBL typically deepens. The inferred shortwave (SW) cloud feedback with a closed energy balance is weakly positive for cumulus clouds. It is more strongly positive for stratocumulus clouds, with a magnitude that increases with warming. Stratocumulus clouds generally break up above 6 K to 9 K warming, or above a four to eightfold increase in CO2 concentrations. This occurs because the MBL mixing driven by cloud-top longwave (LW) cooling weakens as the LW opacity of the free troposphere increases. The stratocumulus breakup triggers an abrupt and large SST increase and MBL deepening, which cannot occur in fixed-SST experiments. SW cloud radiative effects generally weaken while the lower-tropospheric stability increases under warming—the reverse of their empirical relation in the present climate. The MBL is deeper and stratocumulus persists into warmer climates if large-scale subsidence decreases as the climate warms. The contrasts between experiments with interactive SST and fixed SST highlight the importance of a closed surface energy balance for obtaining realizable responses of MBL clouds to warming. © 2016. The Authors."
"24402359000;7003591311;7005920812;","Framework for improvement by vertical enhancement: A simple approach to improve representation of low and high-level clouds in large-scale models",2017,"10.1002/2016MS000815","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017148561&doi=10.1002%2f2016MS000815&partnerID=40&md5=00b96125b23d5e05ed31d7184acda44e","Low and high clouds of shallow extent, especially stratocumulus and even more so for high-level cirrus clouds that reside where vertical resolution is particularly coarse, are poorly represented in large-scale models such as global climate models and weather forecasting models. This adversely affects, among others, estimation of cloud feedbacks for climate prediction and weather forecasts. Here we address vertical resolution as a reason for the failure of these models to adequately represent shallow clouds. We introduce a new methodology, the Framework for Improvement by Vertical Enhancement (FIVE). FIVE computes selected processes on a one-dimensional vertical grid with local high resolution in the boundary layer and near the tropopause. In addition to the host model, variables on the locally high-resolution grid are predicted in parallel so that high-resolution information is retained. By exchanging tendencies with one another, the host model and high-resolution field are always synchronized. The methodology is demonstrated for drizzling stratocumulus capped by a sharp inversion. First, FIVE is applied to a single-column model to identify the cause of biases associated with computing an assigned process at low resolution. Second, a two-dimensional regional model coupled with FIVE is shown to produce results comparable to those performed with high vertical resolution. FIVE is thus expected to represent low clouds more realistically and hence reduce the low-cloud bias in large-scale models. Finally, we propose a number of methods that will be developed and tested to further optimize FIVE. © 2017. The Authors."
"55809947500;55467448100;7005370448;57054708700;","A high performance query analytical framework for supporting data-intensive climate studies",2017,"10.1016/j.compenvurbsys.2016.12.003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006825699&doi=10.1016%2fj.compenvurbsys.2016.12.003&partnerID=40&md5=fa0bf118630cad2801d67f9ef574cd80","Climate observations and model simulations produce vast amounts of data. The unprecedented data volume and the complexity of geospatial statistics and analysis requires efficient analysis of big climate data to investigate global problems such as climate change, natural disasters, diseases, and other environmental issues. This paper introduces a high performance query analytical framework to tackle these challenges by leveraging Hive and cloud computing technologies. With this framework, we propose grid transformation, a new perspective for complex climate analysis that applies a series of atomic transformations to terabytes of climate data using SQL-style query (HiveQL). Specifically, we introduce four types of grid transformations (temporal, spatial, local, and arithmetic) to support a broad range of climate analyses, from the basic spatiotemporal aggregation to more sophisticated anomaly detection. Each query is processed as MapReduce tasks in a highly scalable Hadoop cluster as the parallel processing engine. Big climate data are directly stored and managed in a Hadoop Distributed File System without any data format conversion. A prototype is developed to evaluate the feasibility and performance of the framework. Experimental results show that complex and data-intensive climate analysis can be conducted using intuitive SQL queries with good flexibility and performance. This research provides a building block and practical insights in establishing a cyberinfrastructure that provides a high performance and collaborative environment for data-intensive geospatial applications in climate science. © 2016 Elsevier Ltd"
"7003532926;55008428200;6506333296;6603752490;57193799194;6507368982;6602333928;56828803500;7006113053;","Simulation of modern climate with the new version of the INM RAS climate model",2017,"10.1134/S0001433817020128","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018799043&doi=10.1134%2fS0001433817020128&partnerID=40&md5=cbfe9f0e0fbee6958cfaeadb2dce1206","The INMCM5.0 numerical model of the Earth’s climate system is presented, which is an evolution from the previous version, INMCM4.0. A higher vertical resolution for the stratosphere is applied in the atmospheric block. Also, we raised the upper boundary of the calculating area, added the aerosol block, modified parameterization of clouds and condensation, and increased the horizontal resolution in the ocean block. The program implementation of the model was also updated. We consider the simulation of the current climate using the new version of the model. Attention is focused on reducing systematic errors as compared to the previous version, reproducing phenomena that could not be simulated correctly in the previous version, and modeling the problems that remain unresolved. © 2017, Pleiades Publishing, Ltd."
"24485834000;7103016965;54895140000;6506756436;6602351024;57193095401;57212988186;8701353900;","The “Grey Zone” cold air outbreak global model intercomparison: A cross evaluation using large-eddy simulations",2017,"10.1002/2016MS000822","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010791726&doi=10.1002%2f2016MS000822&partnerID=40&md5=8f9dadf018ff852289b169cbcdb50dbd","A stratocumulus-to-cumulus transition as observed in a cold air outbreak over the North Atlantic Ocean is compared in global climate and numerical weather prediction models and a large-eddy simulation model as part of the Working Group on Numerical Experimentation “Grey Zone” project. The focus of the project is to investigate to what degree current convection and boundary layer parameterizations behave in a scale-adaptive manner in situations where the model resolution approaches the scale of convection. Global model simulations were performed at a wide range of resolutions, with convective parameterizations turned on and off. The models successfully simulate the transition between the observed boundary layer structures, from a well-mixed stratocumulus to a deeper, partly decoupled cumulus boundary layer. There are indications that surface fluxes are generally underestimated. The amount of both cloud liquid water and cloud ice, and likely precipitation, are under-predicted, suggesting deficiencies in the strength of vertical mixing in shear-dominated boundary layers. But also regulation by precipitation and mixed-phase cloud microphysical processes play an important role in the case. With convection parameterizations switched on, the profiles of atmospheric liquid water and cloud ice are essentially resolution-insensitive. This, however, does not imply that convection parameterizations are scale-aware. Even at the highest resolutions considered here, simulations with convective parameterizations do not converge toward the results of convection-off experiments. Convection and boundary layer parameterizations strongly interact, suggesting the need for a unified treatment of convective and turbulent mixing when addressing scale-adaptivity. © 2016. The Authors."
"56494747300;57191981482;6506900387;57196569384;","A rare case of haboob in Tehran: Observational and numerical study",2017,"10.1016/j.atmosres.2016.10.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995579390&doi=10.1016%2fj.atmosres.2016.10.010&partnerID=40&md5=3d60de63b1bf1eb072a9ebe3452276ab","A great dust storm occurred in Tehran on 2 June 2014 and caused severe damage to properties and involved loss of human life. From the visual evidence available, it can be regarded as a case of haboob. As a lower latitude phenomenon, its occurrence in Tehran was unprecedented in the last 50 years. This paper aims to present a detailed analysis of the weather conditions, the pathways by which dust particles were ingested by the haboob, as well as the impact of the urban boundary layer on the intensity and propagation of the dust storm. Using numerical simulation carried out by the WRF-Chem model and various observational techniques, the coupling of a low-level small-scale deformation field with a lower-tropospheric cold pool produced by precipitating mid-tropospheric clouds is identified as the main process involved in shaping this rare dust storm. © 2016 Elsevier B.V."
"57205872550;39261772800;","A review of potential radiative effect of aerosol on climate",2017,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044657790&partnerID=40&md5=2504d85514c2b747753c4dd872a4d0fa","The study of physical and chemical properties of aerosol is of significant importance, because their radiative effects exert strong impact on Earth's climate. Aerosols scatter and absorb solar radiation. Backscattering of solar radiation towards space results loss in surface reaching solar radiation leads to cooling of the climate system. Absorption of solar radiation is associated with heating within the aerosol layer, thereby modifies the vertical temperature profile, and this also results loss in surface reaching solar radiation. Such processes alter the radiative balance of Earth directly so-called direct effects. A subset of aerosols also alters the radiative balance of the Earth by modifying microphysical and radiative properties of clouds via so-called indirect effects. Based on observations and models studies present work suggest that the regional radiative perturbations are several Wm-2 due to changes in aerosol emissions. Furthermore, if the black carbon emission is checked out may lead to a sudden change in the normal pattern of warming/cooling. This paper summarized the various potential radiative mechanisms associated with aerosol-climate interaction. © 2017, National Institute of Science Communication and Information Resources (NISCAIR)."
"53867814800;7005527701;","Brownian coagulation of a bi-modal distribution of both spherical and fractal aerosols",2017,"10.1016/j.jaerosci.2016.11.009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007557343&doi=10.1016%2fj.jaerosci.2016.11.009&partnerID=40&md5=3a8d978d1a0df4e1c1a7f4846366635f","The use of Global Circulation Models (GCM) or mesoscale models are now widely used to understand planetary climatic systems. The increasing complexity of the models and the more and more detailed observations of the planetary bodies necessitate a corresponding increase in the complexity of the physical processes which are included in these models. In all the planetary atmospheres in the solar system, aerosols and clouds can be found and therefore microphysical processes must be included in climate models. The most accurate models are those where aerosol and cloud droplet size distributions are described with bins. This type of sophisticated and accurate models only needs a small quantity of a priori information to be used. However, they are demanding in computational resource. They can only be used in GCM at the cost of very long, and sometime prohibitive, time of computation. Alternatively, an other class of microphysical models, based on the description of the aerosol and cloud distributions with moments of distribution can be used. But, they need first to be developed and compared with a more detailed model and they need an a priori information about the size distributions. In this article, we describe the development of the microphysical equations to treat the interaction of two populations of aerosols, with different geometrical structures, written with moment of distributions, interacting through Brownian coagulation. This problem was solved specifically for the case of Titan, the larger satellite of Saturn, where small aerosols have a spherical shape, large aerosols have a fractal aggregated structure and where aerosols bear an electric charge. The two populations interact in the mesosphere. The fractal structure of the large aerosols also has a consequence on the shape of the size distribution and on the laws of the microphysics that must be accounted a priori in the method. The case of Titan is probably one of the most complex and, in this work, we have written the set of equations in the most general way so they can be used for any other cases. Once developed, we finally compare the results yielded by our new model with the results obtained with the classical model based on a description in bins. © 2016 Elsevier Ltd"
"23974441400;56477833000;56948669100;55544043300;7202019251;","Impact of climate and elevation on snow cover using integrated remote sensing snow products in Tibetan Plateau",2017,"10.1016/j.rse.2016.12.028","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008953589&doi=10.1016%2fj.rse.2016.12.028&partnerID=40&md5=fb80851559539a0000adb41cfd41dea7","Climate change is rapidly altering snow cover conditions in seasonal snow-covered regions of the Tibetan Plateau. This study presents a systematic analysis of the changes in snow cover and its response to climate change on the Tibetan Plateau during the period 2001–2014 using MODIS daily snow cover products under cloud free conditions and AMSR-E SSM/I daily SWE products. The results indicated that 1) the snow-covered area (SCA) tended to increase at elevations below 2000 m.a.s.l., whereas it decreased at elevations above 2000 m.a.s.l. The SCA exhibited a mean decrease over the entire plateau. 2) The SCD and SWE tended to decrease on the Tibetan Plateau, particularly at high elevations. 3) Decreased snowfall and increased rainfall and temperature are the main reasons for the SCD and SWE decrease over the Tibetan Plateau during the period 2001–2014. 4) Snowfall had a positive feedback effect, whereas rainfall and temperature both had negative feedback effects on the attenuation of snow cover. 5) With increasing elevation, the positive feedback of snowfall on snow cover increased significantly, whereas the negative feedback effect of rainfall and temperature also increased. © 2017 Elsevier Inc."
"55713316500;7402146514;55601141900;35205101700;9240820800;","A New Method for Retrieving Daily Land Surface Albedo from VIIRS Data",2017,"10.1109/TGRS.2016.2632624","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017522273&doi=10.1109%2fTGRS.2016.2632624&partnerID=40&md5=6b5d1a76f60984dd6aaf2d79fca32ab0","Unlike instantaneous albedo, daily albedo of land surfaces is currently not routinely generated from satellite data, although it is a key input parameter for calculating daily shortwave radiation budget. This paper presents a novel approach to directly retrieve daily mean values of land surface broadband blue-sky albedo from Visible Infrared Imaging Radiometer Suite clear-sky data of apparent reflectance, with the assumption that the atmospheric conditions of the satellite overpass time can represent their daily values. Training data were simulated by atmospheric radiative transfer models, with surface spectra and bidirectional reflectance distribution function data as inputs for four aerosol types and a range of aerosol loadings. Sensitivity analysis was conducted to study the effects of cloud coverage, aerosol, and surface types on retrieval accuracy. Two years of measurements at six Surface Radiation Budget Network and eight Greenland Climate Network stations were used for algorithm validation. Daily albedo of snow-free surfaces can be retrieved with very high accuracy. By excluding far off-nadir observations of snow surfaces, the overall accuracy of retrieving daily albedo has a bias of 0.003 and a root-mean-square error of 0.055. © 1980-2012 IEEE."
"7006460888;57197927292;7004415966;","Climate patterns of short-wave solar radiation over oceans based on a new parameterization",2017,"10.1134/S0001437017020011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018756396&doi=10.1134%2fS0001437017020011&partnerID=40&md5=ab9d8cd36b26ca4abaaf8f69ed07aa53","The work describes the creation of a new global climatology of short-wave radiation incoming to the ocean surface; the climatology is based on a new parameterization of short-wave fluxes. Advantages of the new parameterization are allowance for nonlinearity of the dependence of the atmospheric transmission factor on the height of the Sun under a clear sky and allowance for different morphological types of clouds under the overcast. It is shown that taking into account these factors leads to substantial differences in short-wave radiation fluxes in comparison to existing parameterizations. © 2017, Pleiades Publishing, Inc."
"55504053900;11940789000;6506539438;7004134577;","Regional dry-season climate changes due to three decades of Amazonian deforestation",2017,"10.1038/nclimate3226","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017471538&doi=10.1038%2fnclimate3226&partnerID=40&md5=5d369cfbf88ef908250ebff19ee40f5b","More than 20% of the Amazon rainforest has been cleared in the past three decades, triggering important hydroclimatic changes. Small-scale (a few kilometres) deforestation in the 1980s has caused thermally triggered atmospheric circulations that increase regional cloudiness and precipitation frequency. However, these circulations are predicted to diminish as deforestation increases. Here we use multi-decadal satellite records and numerical model simulations to show a regime shift in the regional hydroclimate accompanying increasing deforestation in Rondônia, Brazil. Compared with the 1980s, present-day deforested areas in downwind western Rondônia are found to be wetter than upwind eastern deforested areas during the local dry season. The resultant precipitation change in the two regions is approximately ±25% of the deforested area mean. Meso-resolution simulations robustly reproduce this transition when forced with increasing deforestation alone, showing that large-scale climate variability plays a negligible role. Furthermore, deforestation-induced surface roughness reduction is found to play an essential role in the present-day dry-season hydroclimate. Our study illustrates the strong scale sensitivity of the climatic response to Amazonian deforestation and suggests that deforestation is sufficiently advanced to have caused a shift from a thermally to a dynamically driven hydroclimatic regime. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved."
"57192068746;56284582200;8622374000;14045744500;","Modulation of precipitation by conditional symmetric instability release",2017,"10.1016/j.atmosres.2016.10.013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996486938&doi=10.1016%2fj.atmosres.2016.10.013&partnerID=40&md5=2eba44ddae58e9fd36c7dec79169f279","Although many theoretical and observational studies have investigated the mechanism of conditional symmetric instability (CSI) release and associated it with mesoscale atmospheric phenomena such as frontal precipitation bands, cloud heads in rapidly developing extratropical cyclones and sting jets, its climatology and contribution to precipitation have not been extensively documented. The aim of this paper is to quantify the contribution of CSI release, yielding slantwise convection, to climatological precipitation accumulations for the North Atlantic and western Europe. Case studies reveal that CSI release could be common along cold fronts of mature extratropical cyclones and the North Atlantic storm track is found to be a region with large CSI according to two independent CSI metrics. Correlations of CSI with accumulated precipitation are also large in this region and CSI release is inferred to be occurring about 20% of the total time over depths of over 1 km. We conclude that the inability of current global weather forecast and climate prediction models to represent CSI release (due to insufficient resolution yet lack of subgrid parametrization schemes) may lead to errors in precipitation distributions, particularly in the region of the North Atlantic storm track. © 2016"
"23012263800;7004587891;21741206300;57188725919;26421962900;35573513700;36004689700;23492820000;7005780974;57206975350;7006967825;6701436098;7402000409;7801627072;","A 30+ year AVHRR land surface reflectance climate data record and its application to wheat yield monitoring",2017,"10.3390/rs9030296","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019499129&doi=10.3390%2frs9030296&partnerID=40&md5=3a2d403643d244b943b521578a9066c2","The Advanced Very High Resolution Radiometer (AVHRR) sensor provides a unique global remote sensing dataset that ranges from the 1980s to the present. Over the years, several efforts have been made on the calibration of the different instruments to establish a consistent land surface reflectance time-series and to augment the AVHRR data record with data from other sensors, such as the Moderate Resolution Imaging Spectroradiometer (MODIS). In this paper, we present a summary of all the corrections applied to the AVHRR surface reflectance and NDVI Version 4 Product, developed in the framework of the National Oceanic and Atmospheric Administration (NOAA) Climate Data Record (CDR) program. These corrections result from assessment of the geolocation, improvement of cloud masking, and calibration monitoring. Additionally, we evaluate the performance of the surface reflectance over the AERONET sites by a cross-comparison with MODIS, which is an already validated product, and evaluation of a downstream leaf area index (LAI) product. We demonstrate the utility of this long time-series by estimating the winter wheat yield over the USA. The methods developed by Becker-Reshef et al. (2010) and Franch et al. (2015) are applied to both the MODIS and AVHRR data. Comparison of the results from both sensors during the MODIS-era shows the consistency of the dataset with similar errors of 10%. When applying the methods to AVHRR historical data from the 1980s, the results have errors equivalent to those derived from MODIS. © 2017 by the authors."
"7004586688;57193374051;7102757223;6701402091;15724705600;6603035763;16315767700;8245528300;22937577900;35866679700;7005848354;7103363111;6602866287;7006246996;6602125464;57206547313;56431832800;6602389214;7005941690;7005457386;7006575294;7006936301;55476061600;12645612500;6506669380;","The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2): Science requirements, concept, and implementation",2017,"10.1016/j.rse.2016.12.029","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008613355&doi=10.1016%2fj.rse.2016.12.029&partnerID=40&md5=d8068822c991f6ef3015d8dc291d385c","The Ice, Cloud, and land Elevation Satellite (ICESat) mission used laser altimetry measurements to determine changes in elevations of glaciers and ice sheets, as well as sea ice thickness distribution. These measurements have provided important information on the response of the cryopshere (Earth's frozen surfaces) to changes in atmosphere and ocean condition. ICESat operated from 2003 to 2009 and provided repeat altimetry measurements not only to the cryosphere scientific community but also to the ocean, terrestrial and atmospheric scientific communities. The conclusive assessment of significant ongoing rapid changes in the Earth's ice cover, in part supported by ICESat observations, has strengthened the need for sustained, high accuracy, repeat observations similar to what was provided by the ICESat mission. Following recommendations from the National Research Council for an ICESat follow-on mission, the ICESat-2 mission is now under development for planned launch in 2018. The primary scientific aims of the ICESat-2 mission are to continue measurements of sea ice freeboard and ice sheet elevation to determine their changes at scales from outlet glaciers to the entire ice sheet, and from 10s of meters to the entire polar oceans for sea ice freeboard. ICESat carried a single beam profiling laser altimeter that produced ~ 70 m diameter footprints on the surface of the Earth at ~ 150 m along-track intervals. In contrast, ICESat-2 will operate with three pairs of beams, each pair separated by about 3 km cross-track with a pair spacing of 90 m. Each of the beams will have a nominal 17 m diameter footprint with an along-track sampling interval of 0.7 m. The differences in the ICESat-2 measurement concept are a result of overcoming some limitations associated with the approach used in the ICESat mission. The beam pair configuration of ICESat-2 allows for the determination of local cross-track slope, a significant factor in measuring elevation change for the outlet glaciers surrounding the Greenland and Antarctica coasts. The multiple beam pairs also provide improved spatial coverage. The dense spatial sampling eliminates along-track measurement gaps, and the small footprint diameter is especially useful for sea surface height measurements in the often narrow leads needed for sea ice freeboard and ice thickness retrievals. The ICESat-2 instrumentation concept uses a low energy 532 nm (green) laser in conjunction with single-photon sensitive detectors to measure range. Combining ICESat-2 data with altimetry data collected since the start of the ICESat mission in 2003, such as Operation IceBridge and ESA's CryoSat-2, will yield a 15 + year record of changes in ice sheet elevation and sea ice thickness. ICESat-2 will also provide information of mountain glacier and ice cap elevations changes, land and vegetation heights, inland water elevations, sea surface heights, and cloud layering and optical thickness. © 2017"
"57193254578;55754495900;55703823500;","Quantitative analysis of surface warming amplification over the Tibetan Plateau after the late 1990s using surface energy balance equation",2017,"10.1002/asl.732","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012077628&doi=10.1002%2fasl.732&partnerID=40&md5=2e8b52b23caeb9b8e0086b56ec6b8e45","Land surface warming is amplified over the Tibetan Plateau (TP) compared with the global climate warming hiatus since the end of the 1990s. Based on in situ observations and two reanalysis datasets, the processes involved were investigated by calculating partial temperature changes using the surface energy budget equation. The results indicated that the enhanced downward longwave radiation under clear-sky condition and the positive surface albedo feedback (SAF) related to the reduced snow cover are responsible for the pronounced surface warming, especially in winter. Meanwhile, the changes in cloud radiative forcing, surface sensible and latent heat fluxes (H + LE), and heat storage (Q) had a much weaker cooling effect. These results indicate that the enhancement of downward clear-sky longwave radiative fluxes and SAF have played an important role in the accelerated surface warming over the TP during recent decades. © 2017 The Authors. Atmospheric Science Letters published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"56678440200;7004415167;36952455700;57193865585;57210721108;13105152800;56488015600;7004332597;","Effect of reduced PAR on growth and photosynthetic efficiency of soybean genotypes",2017,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017199672&partnerID=40&md5=c5b8025d9b39dcc07952e4f4e3fb80e0","Soybean is an important crop, and physiologically, it is photosensitive in nature and therefore, is likely to be highly affected by the atmospheric brown clouds (ABCs) which reduce PAR (Photosynthetically Active Radiation) availability, and moisture stress conditions those may prevail as a consequence of climate change scenario. Therefore, the impact of reduced natural PAR was evaluated on its determinate (DT; cv. JS-93-05), semi-determinate (SDT; cv. JS-335) and indeterminate (IDT; cv. Kalitur) genotypes. For simulating the reduced PAR condition, three different shapes of structures, viz., rectangular-cuboid, octagonal-dome and hemispherical-dome with shade-net covering were initially tested to check the uniformity of PAR availability inside the structure and the last one was found better. The light saturation point (LSP) was found to be 800, 1200 and 1000 PAR µmol m-2s-1 in case of DT, SDT and IDT genotypes, respectively. Under reduced PAR and restricted irrigation condition, the photosynthetic rate was 20.8, 21.9 and 28.9 µmol m-2s-1 in case of DT, SDT and IDT cultivars, respectively, while their seed yields were 151.3, 238.7 and 264.2 kg ha-1 indicating better source-sink relations of the IDT cultivar. Therefore, it is projected that IDT cultivars are likely to be popular under futuristic scenarios of low PAR availability and water scarcities. © 2017, Association of Agrometeorologists. All rights reserved."
"35868119400;36072775600;35306080000;37762470200;36633454400;57194239759;57194241225;57194236079;34870376900;","Freeze/thaw-induced deformation monitoring and assessment of the slope in permafrost based on terrestrial laser scanner and GNSS",2017,"10.3390/rs9030198","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019491476&doi=10.3390%2frs9030198&partnerID=40&md5=bbd2526b418d9011e6cd12fbdcd7b677","Most previous studies of the Qinghai-Tibet engineering corridor (QTEC) have focused on the impacts of climate change on thaw-induced slope failures, whereas few have considered freeze-induced slope failures. Terrestrial laser scanning was used in combination with global navigation satellite systems to monitor three-dimensional surface changes between 2014 and 2015 on the slope of permafrost in the QTEC, which experienced two thawing periods and a freezing period. Soil temperature and moisture sensors were also deployed at 11 depths to reveal the hydrological-thermal dynamics of the active layer. We analyzed scanned surface changes in the slope based on comparisons of multi-temporal point cloud data to determine how the hydrological-thermal process affected active layer deformation during freeze-thaw cycles, thereby comprehensively quantifying the surface deformation. During the two thawing periods, the major structure of the slope exhibited subsidence trends, whereas the major structure of the slope had an uplift trend in the freezing period. The seasonal subsidence trend was caused by thaw settlement and the seasonal uplift trend was probably due to frost heaving. This occurred mainly because the active layer and the upper permafrost underwent a phase transition due to heat transfer. The ground movements occurred approximately in the soil temperature conduction direction between the top of the soil and the permafrost table. The elevation deformation range was mainly −0.20 m to 0.20 m. Surface volume increases with heaving after freezing could have compensated for the loss of thawing twice and still led to the upward swelling of the slope. Thus, this type of slope in permafrost is dominated by frost heave. Deformation characteristics of the slope will support enhanced decision making regarding the implementation of remote sensing and hydrological-thermal measurement technologies to monitor changes in the slopes in permafrost adjacent to engineering corridors, thereby improving the understanding and assessment of hazards. © 2017 by the authors."
"9739197000;57061641300;15755770600;57148392500;56109267200;23491866500;8407951200;","Tree biomass in the Swiss landscape: nationwide modelling for improved accounting for forest and non-forest trees",2017,"10.1007/s10661-017-5816-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012996219&doi=10.1007%2fs10661-017-5816-7&partnerID=40&md5=ec7c104f0815682c96afeab2f9985aba","Trees outside forest (TOF) can perform a variety of social, economic and ecological functions including carbon sequestration. However, detailed quantification of tree biomass is usually limited to forest areas. Taking advantage of structural information available from stereo aerial imagery and airborne laser scanning (ALS), this research models tree biomass using national forest inventory data and linear least-square regression and applies the model both inside and outside of forest to create a nationwide model for tree biomass (above ground and below ground). Validation of the tree biomass model against TOF data within settlement areas shows relatively low model performance (R2 of 0.44) but still a considerable improvement on current biomass estimates used for greenhouse gas inventory and carbon accounting. We demonstrate an efficient and easily implementable approach to modelling tree biomass across a large heterogeneous nationwide area. The model offers significant opportunity for improved estimates on land use combination categories (CC) where tree biomass has either not been included or only roughly estimated until now. The ALS biomass model also offers the advantage of providing greater spatial resolution and greater within CC spatial variability compared to the current nationwide estimates. © 2017, The Author(s)."
"57193886077;7006422317;57203667028;","Land surface-precipitation feedback analysis for a landfalling monsoon depression in the Indian region",2017,"10.1002/2016MS000829","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017406011&doi=10.1002%2f2016MS000829&partnerID=40&md5=9b9842dd4d372d3d8b213803ee261acd","A series of numerical experiments are carried out to investigate the sensitivity of a landfalling monsoon depression to land surface conditions using the Weather Research and Forecasting (WRF) model. Results suggest that precipitation is largely modulated by moisture influx and precipitation efficiency. Three cloud microphysical schemes (WSM6, WDM6, and Morrison) are examined, and Morrison is chosen for assessing the land surface-precipitation feedback analysis, owing to better precipitation forecast skills. It is found that increased soil moisture facilitates Moisture Flux Convergence (MFC) with reduced moisture influx, whereas a reduced soil moisture condition facilitates moisture influx but not MFC. A higher Moist Static Energy (MSE) is noted due to increased evapotranspiration in an elevated moisture scenario which enhances moist convection. As opposed to moist surface, sensible heat dominates in a reduced moisture scenario, ensued by an overall reduction in MSE throughout the Planetary Boundary Layer (PBL). Stability analysis shows that Convective Available Potential Energy (CAPE) is comparable in magnitude for both increased and decreased moisture scenarios, whereas Convective Inhibition (CIN) shows increased values for the reduced moisture scenario as a consequence of drier atmosphere leading to suppression of convection. Simulations carried out with various fixed soil moisture levels indicate that the overall precipitation features of the storm are characterized by initial soil moisture condition, but precipitation intensity at any instant is modulated by soil moisture availability. Overall results based on this case study suggest that antecedent soil moisture plays a crucial role in modulating precipitation distribution and intensity of a monsoon depression. © 2017. The Authors."
"15762914300;56422232000;56486548700;57190568320;55533645800;","Coupling of phenological information and simulated vegetation index time series: Limitations and potentials for the assessment and monitoring of soil erosion risk",2017,"10.1016/j.catena.2016.11.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84998717652&doi=10.1016%2fj.catena.2016.11.016&partnerID=40&md5=e520c1a8000af416fd4bcf09d516c539","Monitoring of soils used for agriculture at frequent intervals is crucial to support decision making and refining soil policies especially in the context of climate change. Along with rainfall erosivity, soil coverage by vegetation or crop residues is the most dynamic factor affecting soil erosion. Parcel-specific soil coverage information can be derived by satellite imagery with high geometric resolution. However, their usable number is mostly, due to cloud cover, not representative for the phenological characteristics of vegetated classes. To overcome temporal constraints, spatial and temporal fusion models, such as STARFM, are increasingly applied to derive high-resolution time series of remotely sensed biophysical parameters, based on fine spatial/coarse temporal resolution imagery, such as Landsat, and coarse spatial/fine temporal resolution imagery, such as MODIS. In this context, the current study introduces an evaluation scheme for simulated vegetation index time series which enables the assessment of their performance during multiple phenological phases. The evaluation scheme is based on Germany-wide available spatial predictions of phenological phases as well as RapidEye imagery and parcel-specific crop-type information. The evaluation results show that the simulation accuracy is basically controlled by the temporal distance between MODIS and Landsat base pairs, as well as the ability of the actual Landsat image to properly represent the phenological phase of the Landsat image simulated by MODIS. In addition, we discuss the potential of simulated index times series and corresponding phenological information for the dynamic (1) definition of temporal windows where soils are potentially covered by no, sparse or dense vegetation or crop residues and (2) parameterization of soil erosion models. The database thus obtained opens up new possibilities for an efficient and dynamic erosion monitoring, which can support soil protection and hazard prevention. © 2016 Elsevier B.V."
"57193217667;14009374600;55530911200;35175400200;7409077047;","Estimation of downwelling surface longwave radiation under heavy dust aerosol sky",2017,"10.3390/rs9030207","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019360001&doi=10.3390%2frs9030207&partnerID=40&md5=2032e1068a2c9a2c591acc2ecbf79372","The variation of aerosols, especially dust aerosol, in time and space plays an important role in climate forcing studies. Aerosols can effectively reduce land surface longwave emission and re-emit energy at a colder temperature, which makes it difficult to estimate downwelling surface longwave radiation (DSLR) with satellite data. Using the latest atmospheric radiative transfer code (MODTRAN 5.0), we have simulated the outgoing longwave radiation (OLR) and DSLR under different land surface types and atmospheric profile conditions. The results show that dust aerosol has an obvious ""warming"" effect to longwave radiation compared with other aerosols; that aerosol longwave radiative forcing (ALRF) increased with the increasing of aerosol optical depth (AOD); and that the atmospheric water vapor content (WVC) is critical to the understanding of ALRF. A method is proposed to improve the accuracy of DSLR estimation from satellite data for the skies under heavy dust aerosols. The AOD and atmospheric WVC under cloud-free conditions with a relatively simple satellite-based radiation model yielding the high accurate DSLR under heavy dust aerosol are used explicitly as model input to reduce the effects of dust aerosol on the estimation of DSLR. Validations of the proposed model with satellites data and field measurements show that it can estimate the DSLR accurately under heavy dust aerosol skies. The root mean square errors (RMSEs) are 20.4 W/m2 and 24.2 W/m2 for Terra and Aqua satellites, respectively, at the Yingke site, and the biases are 2.7 W/m2 and 9.6 W/m2, respectively. For the Arvaikheer site, the RMSEs are 23.2 W/m2 and 19.8 W/m2 for Terra and Aqua, respectively, and the biases are 7.8 W/m2 and 10.5 W/m2, respectively. The proposed method is especially applicable to acquire relatively high accurate DSLR under heavy dust aerosol using MODIS data with available WVC and AOD data. © 2017 by the authors."
"7103180783;7402401574;6506298579;","Understanding the rapid summer warming and changes in temperature extremes since the mid-1990s over Western Europe",2017,"10.1007/s00382-016-3158-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966292302&doi=10.1007%2fs00382-016-3158-8&partnerID=40&md5=a366b71fbde36e8772284a48561593ee","Analysis of observations indicates that there was a rapid increase in summer (June–August) mean surface air temperature (SAT) since the mid-1990s over Western Europe. Accompanying this rapid warming are significant increases in summer mean daily maximum temperature, daily minimum temperature, annual hottest day temperature and warmest night temperature, and an increase in frequency of summer days and tropical nights, while the change in the diurnal temperature range (DTR) is small. This study focuses on understanding causes of the rapid summer warming and associated temperature extreme changes. A set of experiments using the atmospheric component of the state-of-the-art HadGEM3 global climate model have been carried out to quantify relative roles of changes in sea surface temperature (SST)/sea ice extent (SIE), anthropogenic greenhouse gases (GHGs), and anthropogenic aerosols (AAer). Results indicate that the model forced by changes in all forcings reproduces many of the observed changes since the mid-1990s over Western Europe. Changes in SST/SIE explain 62.2 ± 13.0 % of the area averaged seasonal mean warming signal over Western Europe, with the remaining 37.8 ± 13.6 % of the warming explained by the direct impact of changes in GHGs and AAer. Results further indicate that the direct impact of the reduction of AAer precursor emissions over Europe, mainly through aerosol-radiation interaction with additional contributions from aerosol-cloud interaction and coupled atmosphere-land surface feedbacks, is a key factor for increases in annual hottest day temperature and in frequency of summer days. It explains 45.5 ± 17.6 % and 40.9 ± 18.4 % of area averaged signals for these temperature extremes. The direct impact of the reduction of AAer precursor emissions over Europe acts to increase DTR locally, but the change in DTR is countered by the direct impact of GHGs forcing. In the next few decades, greenhouse gas concentrations will continue to rise and AAer precursor emissions over Europe and North America will continue to decline. Our results suggest that the changes in summer seasonal mean SAT and temperature extremes over Western Europe since the mid-1990s are most likely to be sustained or amplified in the near term, unless other factors intervene. © 2016, The Author(s)."
"56536745100;7005304841;57203053317;","Cloud response and feedback processes in stratiform mixed-phase clouds perturbed by ship exhaust",2017,"10.1002/2016GL071358","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013382124&doi=10.1002%2f2016GL071358&partnerID=40&md5=1fe8ce558d585fe2f699f463fa3614a5","Stratiform mixed-phase clouds (MPCs), which contain both supercooled liquid and ice, play a key role in the energy balance of the Arctic and are a major contributor to surface precipitation. As Arctic shipping is projected to increase with climate change, these clouds may frequently be exposed to local aerosol perturbations of up to 15,000 cm−3. Yet little consensus exists within the community regarding the key feedback mechanisms induced in MPCs perturbed by ship exhaust, or aerosol in general. Here we show that many known processes identified in the warm-phase stratocumulus regime can be extrapolated to the MPC regime. However, their effect may be compensated, or even undermined, by the following two most relevant processes unique to the MPC regime: (i) increased cloud glaciation via immersion freezing due to cloud condensation nuclei (CCN) induced cloud top radiative cooling and (ii) the continued cycling of ice nucleating particles (INPs) through the cloud and subcloud layer. ©2017. The Authors."
"57193412000;57135529200;14051038900;57203053066;25635521800;","Regional variations in the ocean response to tropical cyclones: Ocean mixing versus low cloud suppression",2017,"10.1002/2016GL072023","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013629656&doi=10.1002%2f2016GL072023&partnerID=40&md5=50d3e9a95f5ead4b0fd87f94e35bae70","Tropical cyclones (TCs) tend to cool sea surface temperature (SST) via enhanced vertical mixing and evaporative fluxes. This cooling is substantially reduced in the subtropics, especially in the northeastern Pacific where the occurrence of TCs can warm the ocean surface. Here we investigate the cause of this anomalous warming by analyzing the local oceanic features and TC-induced anomalies of SST, surface fluxes, and cloud fraction using satellite and in situ data. We find that TCs tend to suppress low clouds at the margins of the tropical ocean warm pool, enhancing shortwave radiative surface fluxes within the first week following storm passage, which, combined with spatial variations in ocean thermal structure, can produce a ~1°C near-surface warming in the northeastern Pacific. These findings, supported by high-resolution Earth system model simulations, point to potential connections between TCs, ocean temperature, and low cloud distributions that can influence tropical surface heat budgets. ©2017. American Geophysical Union. All Rights Reserved."
"56451380500;55917255400;","Meteorological anomalies lead to elevated O3 in the western U.S. in June 2015",2017,"10.1002/2016GL072010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013455583&doi=10.1002%2f2016GL072010&partnerID=40&md5=2c3c531b414095ee46bfcbef07854c89","In winter through early summer of 2014–2015, temperatures in the western U.S. were substantially enhanced due to a persistent high-pressure ridge and warm water in the northeastern Pacific Ocean. Concurrently, monthly averaged maximum daily 8 h average (MDA8) O3 in June 2015 was enhanced by 3–13 ppb across a large portion of the western U.S. At the Mount Bachelor Observatory (2.8 km above sea level) in central Oregon, O3 in June 2015 was enhanced by 11 ppbv compared to the long-term mean. Some urban areas had many days in June 2015 with MDA8 values above the current air quality threshold of 70 ppbv. We show that the high O3 was associated with enhanced temperatures, reduced cloud fraction, increased stagnation, and increased biogenic emissions. The data in June 2015 show enhanced ΔO3/Δtemperature slopes at several sites, compared to previous June data, due to these multiple factors. ©2017. American Geophysical Union. All Rights Reserved."
"8972504300;23096635200;","Initiation of Snowball Earth with volcanic sulfur aerosol emissions",2017,"10.1002/2016GL072335","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013498697&doi=10.1002%2f2016GL072335&partnerID=40&md5=e5986a258b03564a882e4af5e6ff8789","We propose that the first Neoproterozoic Snowball Earth event, the Sturtian glaciation, was initiated by the injection of sulfate aerosols into the stratosphere. Geochronological data indicate that the Natkusiak magmatic assemblage of the Franklin large igneous province coincided with onset of the Sturtian glaciation. The Natkusiak was emplaced into an evaporite basin and entrained significant quantities of sulfur, which would have led to extensive SO2 and H2S outgassing in hot convective plumes. The largest of these plumes could have penetrated the tropopause, leading to stratospheric sulfate aerosol formation and an albedo increase sufficient to force a Snowball. Radiative forcing was maximized by the equatorial location of the Franklin and the cool Neoproterozoic background climate, which would have lowered the tropopause height, increasing the rate of stratospheric aerosol injection. Our results have implications for understanding Phanerozoic mass extinction events, exoplanet habitability, and aerosol perturbations to the present-day climate. ©2017. American Geophysical Union. All Rights Reserved."
"55767074400;55867089500;21738966900;55340337800;7003499456;","Can climate-effective land management reduce regional warming?",2017,"10.1002/2016JD026125","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014155832&doi=10.1002%2f2016JD026125&partnerID=40&md5=36408bd7e4cddff756746d6028eeebe7","Limiting global warming to well below 2°C is an imminent challenge for humanity. However, even if this global target can be met, some regions are still likely to experience substantial warming relative to others. Using idealized global climate simulations, we examine the potential of land management options in affecting regional climate, with a focus on crop albedo enhancement and irrigation (climate-effective land management). The implementation is performed over all crop regions globally to provide an upper bound. We find that the implementation of both crop albedo enhancement and irrigation can reduce hot temperature extremes by more than 2°C in North America, Eurasia, and India over the 21st century relative to a scenario without management application. The efficacy of crop albedo enhancement scales with the magnitude, where a cooling response exceeding 0.5°C for hot temperature extremes was achieved with a large (i.e., ≥0.08) change in crop albedo. Regional differences were attributed to the surface energy balance response with temperature changes mostly explained by latent heat flux changes for irrigation and net shortwave radiation changes for crop albedo enhancement. However, limitations do exist, where we identify warming over the winter months when climate-effective land management is temporarily suspended. This was associated with persistent cloud cover that enhances longwave warming. It cannot be confirmed if the magnitude of this feedback is reproducible in other climate models. Our results overall demonstrate that regional warming of hot extremes in our climate model can be partially mitigated when using an idealized treatment of climate-effective land management. © 2017. The Authors."
"23493942300;55730024300;22986631300;8720083500;53981601100;56227660900;55710051100;35191486300;36494729400;","An agricultural biomass burning episode in eastern China: Transport, optical properties, and impacts on regional air quality",2017,"10.1002/2016JD025319","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013466649&doi=10.1002%2f2016JD025319&partnerID=40&md5=57b8b713c93513821c0ef0a4c377be84","Agricultural biomass burning (ABB) has been of particular concern due to its influence on air quality and atmospheric radiation, as it produces large amounts of gaseous and aerosol emissions. This paper presents an integrated observation of a significant ABB episode in Nanjing, China, during early June 2011, using combined ground-based and satellite sensors (Moderate Resolution Imaging Spectroradiometer, Atmospheric Infrared Sounder, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), and Ozone Monitoring Instrument products). The time-height distribution, optical properties, sources and transport of smoke, and its impacts on air quality are investigated. Lidar profiles indicate that the smoke aerosols are confined to the planetary boundary layer (PBL) and have a depolarization ratio of less than 0.08. The aerosol optical depths increase from 0.5 to 3.0 at 500 nm, while the extinction-related Angstrom exponent increases from 1.1 to 1.6 at the wavelength pair of 440-870 nm. The single-scattering albedo becomes lower at 670-1020nm following the ABB intrusion and particularly shows a decreasing tendency between wavelengths of 440 to 1020 nm. The absorption Angstrom exponent (0.7) is smaller than 1.0, which may indicate the aged smoke particles mixed or coated with the urban aerosols. Surface particular matter PM10 and PM2.5 show a dramatic increase, reaching hourly mean of 800 µg/m3 and 485 µg/m3, respectively, which results in a heavy air pollution event. The stagnant and high-moisture weather provides favorable conditions for the aerosols to accumulate near the surface. Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) also illustrate that the large-scale aerosols are primarily present in the PBL and transported to the ocean, but some dense smoke plumes are misclassified as cloud or polluted dust. By comparing with the observations, we found that the Weather Research and Forecasting-Chemistry model captured the accumulation and downwind transport of surface PM2.5 from 20:00 on 2 June to 10:00 on 3 June (phase 1) but showed a dramatic underestimate from 20:00 on 3-4 June (phase 2) when dense aerosols are present. Such a discrepancy in the model is associated with the improper vertical apportion of transported smoke and atmospheric diffusion conditions when comparing with the observed aerosol and wind profiles. In addition, the model simulations indicate that the transported smoke can contribute to 50-70% of the ground-level PM2.5 in Nanjing. © 2017. American Geophysical Union. All Rights Reserved."
"26653789100;57203108896;","A cloud feedback emulator (CFE, version 1.0) for an intermediate complexity model",2017,"10.5194/gmd-10-945-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014004958&doi=10.5194%2fgmd-10-945-2017&partnerID=40&md5=50acf6667919894955a837b7863bf21e","The dominant source of inter-model differences in comprehensive global climate models (GCMs) are cloud radiative effects on Earth's energy budget. Intermediate complexity models, while able to run more efficiently, often lack cloud feedbacks. Here, we describe and evaluate a method for applying GCM-derived shortwave and longwave cloud feedbacks from 4 × CO2 and Last Glacial Maximum experiments to the University of Victoria Earth System Climate Model. The method generally captures the spread in top-of-the-atmosphere radiative feedbacks between the original GCMs, which impacts the magnitude and spatial distribution of surface temperature changes and climate sensitivity. These results suggest that the method is suitable to incorporate multi-model cloud feedback uncertainties in ensemble simulations with a single intermediate complexity model. © Author(s) 2017."
"57193388226;6507562207;6603983857;55826107700;6603062699;","Enabling BOINC in infrastructure as a service cloud system",2017,"10.5194/gmd-10-811-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013466640&doi=10.5194%2fgmd-10-811-2017&partnerID=40&md5=694e3f1702a3eecc7f6f5d7c7a3cbe98","Volunteer or crowd computing is becoming increasingly popular for solving complex research problems from an increasingly diverse range of areas. The majority of these have been built using the Berkeley Open Infrastructure for Network Computing (BOINC) platform, which provides a range of different services to manage all computation aspects of a project. The BOINC system is ideal in those cases where not only does the research community involved need low-cost access to massive computing resources but also where there is a significant public interest in the research being done. We discuss the way in which cloud services can help BOINC-based projects to deliver results in a fast, on demand manner. This is difficult to achieve using volunteers, and at the same time, using scalable cloud resources for short on demand projects can optimize the use of the available resources. We show how this design can be used as an efficient distributed computing platform within the cloud, and outline new approaches that could open up new possibilities in this field, using Climateprediction.net (http://www.climateprediction.net/) as a case study. © 2017 The Author(s)."
"35096299800;6701588531;7006705919;55688930000;","Technical note: Simultaneous fully dynamic characterization of multiple input-output relationships in climate models",2017,"10.5194/acp-17-2525-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013149709&doi=10.5194%2facp-17-2525-2017&partnerID=40&md5=c7d1f7c6cdbf1ce49b9ee576453134c7","We introduce system identification techniques to climate science wherein multiple dynamic input-output relationships can be simultaneously characterized in a single simulation. This method, involving multiple small perturbations (in space and time) of an input field while monitoring output fields to quantify responses, allows for identification of different timescales of climate response to forcing without substantially pushing the climate far away from a steady state. We use this technique to determine the steady-state responses of low cloud fraction and latent heat flux to heating perturbations over 22 regions spanning Earth's oceans. We show that the response characteristics are similar to those of step-change simulations, but in this new method the responses for 22 regions can be characterized simultaneously. Furthermore, we can estimate the timescale over which the steady-state response emerges. The proposed methodology could be useful for a wide variety of purposes in climate science, including characterization of teleconnections and uncertainty quantification to identify the effects of climate model tuning parameters. © 2017 Author(s)."
"56898191700;7404764644;56486548700;30067702800;55102510300;7006413710;6603378706;7006200031;15123538900;7402760408;","Daily Landsat-scale evapotranspiration estimation over a forested landscape in North Carolina, USA, using multi-satellite data fusion",2017,"10.5194/hess-21-1017-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013082960&doi=10.5194%2fhess-21-1017-2017&partnerID=40&md5=a1d39bfb35f4737ca16d6dcbf755482d","As a primary flux in the global water cycle, evapotranspiration (ET) connects hydrologic and biological processes and is directly affected by water and land management, land use change and climate variability. Satellite remote sensing provides an effective means for diagnosing ET patterns over heterogeneous landscapes; however, limitations on the spatial and temporal resolution of satellite data, combined with the effects of cloud contamination, constrain the amount of detail that a single satellite can provide. In this study, we describe an application of a multi-sensor ET data fusion system over a mixed forested/agricultural landscape in North Carolina, USA, during the growing season of 2013. The fusion system ingests ET estimates from the Two-Source Energy Balance Model (TSEB) applied to thermal infrared remote sensing retrievals of land surface temperature from multiple satellite platforms: hourly geostationary satellite data at 4 km resolution, daily 1 km imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) and biweekly Landsat thermal data sharpened to 30 m. These multiple ET data streams are combined using the Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) to estimate daily ET at 30m resolution to investigate seasonal water use behavior at the level of individual forest stands and land cover patches. A new method, also exploiting the STARFM algorithm, is used to fill gaps in the Landsat ET retrievals due to cloud cover and/or the scan-line corrector (SLC) failure on Landsat 7. The retrieved daily ET time series agree well with observations at two AmeriFlux eddy covariance flux tower sites in a managed pine plantation within the modeling domain: US-NC2 located in a mid-rotation (20-year-old) loblolly pine stand and USNC3 located in a recently clear-cut and replanted field site. Root mean square errors (RMSEs) for NC2 and NC3 were 0.99 and 1.02mmday-1, respectively, with mean absolute errors of approximately 29% at the daily time step, 12% at the monthly time step and 0.7% over the full study period at the two flux tower sites. Analyses of water use patterns over the plantation indicate increasing seasonal ET with stand age for young to mid-rotation stands up to 20 years, but little dependence on age for older stands. An accounting of consumptive water use by major land cover classes representative of the modeling domain is presented, as well as relative partitioning of ET between evaporation (E) and transpiration (T ) components obtained with the TSEB. The study provides new insights about the effects of management and land use change on water yield over forested landscapes. © Author(s) 2017. CC Attribution 3.0 License."
"57214563572;54415303600;56123335600;56415732200;57095210500;7102423967;35735005100;57200702127;10241807900;55258548500;55494568400;57205707345;57191406376;7404865816;","Aerosol vertical distribution and optical properties over China from long-term satellite and ground-based remote sensing",2017,"10.5194/acp-17-2509-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013175525&doi=10.5194%2facp-17-2509-2017&partnerID=40&md5=285a6cfbfbc71892652bf853126a8833","The seasonal and spatial variations of vertical distribution and optical properties of aerosols over China are studied using long-term satellite observations from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and ground-based lidar observations and Aerosol Robotic Network (AERONET) data. The CALIOP products are validated using the ground-based lidar measurements at the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL). The Taklamakan Desert and Tibetan Plateau regions exhibit the highest depolarization and color ratios because of the natural dust origin, whereas the North China Plain, Sichuan Basin and Yangtze River Delta show the lowest depolarization and color ratios because of aerosols from secondary formation of the anthropogenic origin. Certain regions, such as the North China Plain in spring and the Loess Plateau in winter, show intermediate depolarization and color ratios because of mixed dust and anthropogenic aerosols. In the Pearl River Delta region, the depolarization and color ratios are similar to but higher than those of the other polluted regions because of combined anthropogenic and marine aerosols. Long-range transport of dust in the middle and upper troposphere in spring is well captured by the CALIOP observations. The seasonal variations in the aerosol vertical distributions reveal efficient transport of aerosols from the atmospheric boundary layer to the free troposphere because of summertime convective mixing. The aerosol extinction lapse rates in autumn and winter are more positive than those in spring and summer, indicating trapped aerosols within the boundary layer because of stabler meteorological conditions. More than 80ĝ€% of the column aerosols are distributed within 1.5ĝ€km above the ground in winter, when the aerosol extinction lapse rate exhibits a maximum seasonal average in all study regions except for the Tibetan Plateau. The aerosol extinction lapse rates in the polluted regions are higher than those of the less polluted regions, indicating a stabilized atmosphere due to absorptive aerosols in the polluted regions. Our results reveal that the satellite and ground-based remote-sensing measurements provide the key information on the long-term seasonal and spatial variations in the aerosol vertical distribution and optical properties, regional aerosol types, long-range transport and atmospheric stability, which can be utilized to more precisely assess the direct and indirect aerosol effects on weather and climate. © 2017 Author(s). CC Attribution 3.0 License."
"57189755950;7005137442;","Observational evidence against strongly stabilizing tropical cloud feedbacks",2017,"10.1002/2016GL072202","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012104637&doi=10.1002%2f2016GL072202&partnerID=40&md5=e12c094a1dd4398a4818942a8682e35b","We present a method to attribute cloud radiative feedbacks to convective processes, using subcloud layer buoyancy as a diagnostic of stable and deep convective regimes. Applying this approach to tropical remote sensing measurements over years 2000–2016 shows that an inferred negative short-term cloud feedback from deep convection was nearly offset by a positive cloud feedback from stable regimes. The net cloud feedback was within statistical uncertainty of the National Center for Atmospheric Research Community Atmosphere Model (CAM5) with historical forcings, with discrepancies in the partitioning of the cloud feedback into convective regimes. Compensation between high-cloud responses to tropics-wide warming in stable and unstable regimes resulted in smaller net changes in high-cloud fraction with warming. In addition, deep convection and associated high clouds set in at warmer temperatures in response to warming, as a consequence of nearly invariant subcloud buoyancy. This invariance further constrained the magnitude of cloud radiative feedbacks and is consistent with climate model projections. Published 2017. This article is a US Government work and is in the public domain in the United States of America."
"56457851700;12801992200;57193327928;7202145115;24722339600;16444006500;","The global aerosol-cloud first indirect effect estimated using MODIS, MERRA, and AeroCom",2017,"10.1002/2016JD026141","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012993562&doi=10.1002%2f2016JD026141&partnerID=40&md5=2a2a5a92fed4f68857492a82ce3f273d","Aerosol-cloud interactions (ACI) represent a significant source of forcing uncertainty in global climate models (GCMs). Estimates of radiative forcing due to ACI in Fifth Assessment Report range from -0.5 to -2.5Wm-2. A portion of this uncertainty is related to the first indirect, or Twomey, effect whereby aerosols act as nuclei for cloud droplets to condense upon. At constant liquid water content this increases the number of cloud droplets (Nd) and thus increases the cloud albedo. In this study we use remote-sensing estimates of Nd within stratocumulus regions in combination with state-of-the-art aerosol reanalysis from Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA2) to diagnose how aerosols affect Nd. As in previous studies, Nd is related to sulfate mass through a power law relationship. The slope of the log-log relationship between Nd and SO4 in maritime stratocumulus is found to be 0.31, which is similar to the range of 0.2-0.8 from previous in situ studies and remote-sensing studies in the pristine Southern Ocean. Using preindustrial emissions models, the change in Nd between preindustrial and present day is estimated. Nd is inferred to have more than tripled in some regions. Cloud properties from Moderate Resolution Imaging Spectroradiometer (MODIS) are used to estimate the radiative forcing due to this change in Nd. The Twomey effect operating in isolation is estimated to create a radiative forcing of -0.97 ± 0.23Wm-2 relative to the preindustrial era. © 2017. American Geophysical Union. All Rights Reserved."
"36753174700;35285676700;55337259400;7402711358;7006783796;7003475277;25029309200;26643481800;","Improved modeling of cloudy-sky actinic flux using satellite cloud retrievals",2017,"10.1002/2016GL071892","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012107892&doi=10.1002%2f2016GL071892&partnerID=40&md5=6b9908ac916a65de98d8b2b9a00c63d0","Clouds play a critical role in modulating tropospheric radiation and thus photochemistry. We develop a methodology for calculating the vertical distribution of tropospheric ultraviolet (300–420 nm) actinic fluxes using satellite cloud retrievals and a radiative transfer model. We demonstrate that our approach can accurately reproduce airborne-measured actinic fluxes from the 2013 Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign as a case study. The results show that the actinic flux is reduced below moderately thick clouds with increasing cloud optical depth and can be enhanced by a factor of 2 above clouds. Inside clouds, the actinic flux can be enhanced by up to 2.4 times in the upper part of clouds or reduced up to 10 times in the lower parts of clouds. Our study suggests that the use of satellite-derived actinic fluxes as input to chemistry-transport models can improve the accuracy of photochemistry calculations. ©2017. The Authors."
"55331697200;7005650812;7405763496;8117864800;","Idealized numerical experiments on the microphysical evolution of warm-type heavy rainfall",2017,"10.1002/2016JD025637","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013667269&doi=10.1002%2f2016JD025637&partnerID=40&md5=8218f3ed15ab249b099c6d56f9bb0d4a","Recent satellite observations suggested that medium-depth heavy rain systems (i.e., warm-type heavy rainfall) were predominantly found in the Korean peninsula under moist-adiabatically near neutral conditions in contrast to the traditional view that deep convection induced by convective instability produced heavy rainfall (i.e., cold-type heavy rainfall). In order to examine whether a numerical model could explain the microphysical evolution of the warm-type as well as cold-type heavy rainfall, numerical experiments were implemented with idealized thermodynamic conditions. Under the prescribed humid and weakly unstable conditions, the warm-type experiments resulted in a lower storm height, earlier onset of precipitation, and heavier precipitation than was found for the cold-type experiments. The growth of ice particles and their melting process were important for developing cold-type heavy rainfall. In contrast, the collision and coalescence processes between liquid particles were shown to be the mechanism for increasing the radar reflectivity toward the surface in the storm core region for the warm-type heavy rainfall. © 2017. The Authors."
"57192063986;23048575400;7103204204;6603382350;56363987000;57190209035;","Directional, horizontal inhomogeneities of cloud optical thickness fields retrieved from ground-based and airbornespectral imaging",2017,"10.5194/acp-17-2359-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012993368&doi=10.5194%2facp-17-2359-2017&partnerID=40&md5=8a2df399876cf12c798c22edf21d99e2","Clouds exhibit distinct horizontal inhomogeneities of their optical and microphysical properties, which complicate their realistic representation in weather and climate models. In order to investigate the horizontal structure of cloud inhomogeneities, 2-D horizontal fields of optical thickness (τ) of subtropical cirrus and Arctic stratus are investigated with a spatial resolution of less than 10m. The 2-D τ-fields are derived from (a) downward (transmitted) solar spectral radiance measurements from the ground beneath four subtropical cirrus and (b) upward (reflected) radiances measured from aircraft above 10 Arctic stratus. The data were collected during two field campaigns: (a) Clouds, Aerosol, Radiation, and tuRbulence in the trade wind regime over BArbados (CARRIBA) and (b) VERtical Distribution of Ice in Arctic clouds (VERDI). One-dimensional and 2-D autocorrelation functions, as well as power spectral densities, are derived from the retrieved τ-fields. The typical spatial scale of cloud inhomogeneities is quantified for each cloud case. Similarly, the scales at which 3-D radiative effects influence the radiance field are identified. In most of the investigated cloud cases considerable cloud inhomogeneities with a prevailing directional structure are found. In these cases, the cloud inhomogeneities favour a specific horizontal direction, while across this direction the cloud is of homogeneous character. The investigations reveal that it is not sufficient to quantify horizontal cloud inhomogeneities using 1-D inhomogeneity parameters; 2-D parameters are necessary. © 2017 The Author(s)."
"55703069400;56279208100;7102963655;","Characterisation of Special Sensor Microwave Water Vapor Profiler (SSM/T-2) radiances using radiative transfer simulations from global atmospheric reanalyses",2017,"10.1016/j.asr.2016.11.017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008173385&doi=10.1016%2fj.asr.2016.11.017&partnerID=40&md5=e265b04f180d04fff5947d208754cc0c","The near-global and all-sky coverage of satellite observations from microwave humidity sounders operating in the 183 GHz band complement radiosonde and aircraft observations and satellite infrared clear-sky observations. The Special Sensor Microwave Water Vapor Profiler (SSM/T-2) of the Defense Meteorological Satellite Program began operations late 1991. It has been followed by several other microwave humidity sounders, continuing today. However, expertise and accrued knowledge regarding the SSM/T-2 data record is limited because it has remained underused for climate applications and reanalyses. In this study, SSM/T-2 radiances are characterised using several global atmospheric reanalyses. The European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Reanalysis (ERA-Interim), the first ECMWF reanalysis of the 20th-century (ERA-20C), and the Japanese 55-year Reanalysis (JRA-55) are projected into SSM/T-2 radiance space using a fast radiative transfer model. The present study confirms earlier indications that the polarisation state of SSM/T-2 antenna is horizontal (not vertical) in the limit of nadir viewing. The study also formulates several recommendations to improve use of the SSM/T-2 measurement data in future fundamental climate data records or reanalyses. Recommendations are (1) to correct geolocation errors, especially for DMSP 14; (2) to blacklist poor quality data identified in the paper; (3) to correct for inter-satellite biases, estimated here on the order of 1 K, by applying an inter-satellite recalibration or, for reanalysis, an automated (e.g., variational) bias correction; and (4) to improve precipitating cloud filtering or, for reanalysis, consider an all-sky assimilation scheme where radiative transfer simulations account for the scattering effect of hydrometeors. © 2016"
"55901813900;57197568533;","The performance of three fog gauges under field conditions and its relationship with meteorological variables in an exposed site in Tenerife (Canary Islands)",2017,"10.1016/j.agrformet.2016.11.009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84997294375&doi=10.1016%2fj.agrformet.2016.11.009&partnerID=40&md5=e8476eef50f8446ff0e9452ee23ac271","We characterized the fog phenomena and associated micrometeorological variables in a 1093 m a.s.l. site in Tenerife (Canary Islands) during a 42 months period with three different fog gauges. Fog was more frequent during night-time and early morning, concomitantly with a reduction in ambient temperature and an increase in wind velocity (u). Furthermore, diurnal hourly medians of both reference evapotranspiration (r2 ≥ 0.75) and net radiation (r2 ≥ 0.95) were linearly correlated during foggy versus fog free conditions. Such correlations were different depending on whether fog was light (i.e. visibility, Ω &gt; 200 m) or dense (Ω &lt; 200 m). Although the actual gauge's fog water collection (FWC) depends on many concurrent factors and it is nonlinearly related to the micrometeorological variables, thus difficult to predict, the curves fitting the maxima of FWC vs. Ω and FWC vs. u data were shown to be a good descriptor of the fog water collection potential of the site. Some bounds were established on such envelope curves during strong wind gusts in terms of the force balance that lead to re-entrainment and clogging of a particular gauge screen by water drops with different geometry. The results presented advance on the possibility of relating ground base local measurements of fog water yield with the remote monitoring of auxiliary meteorological variables, such as the visibility, in order to characterize broad areas for their fog water harvesting potential, either for its exploitation or its effect on cloud immersed forests. © 2016 Elsevier B.V."
"36678944300;56487065200;57193254488;56532611600;25723426400;55868743000;23399196900;","Effects of atmospheric dynamics and aerosols on the fraction of supercooled water clouds",2017,"10.5194/acp-17-1847-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012060173&doi=10.5194%2facp-17-1847-2017&partnerID=40&md5=e2c7715d3319ad536e5dd9a1639a5246","Based on 8 years of (January 2008-December 2015) cloud phase information from the GCM-Oriented Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) Cloud Product (GOCCP), aerosol products from CALIPSO and meteorological parameters from the ERA-Interim products, the present study investigates the effects of atmospheric dynamics on the supercooled liquid cloud fraction (SCF) during nighttime under different aerosol loadings at global scale to better understand the conditions of supercooled liquid water gradually transforming to ice phase. Statistical results indicate that aerosols' effect on nucleation cannot fully explain all SCF changes, especially in those regions where aerosols' effect on nucleation is not a first-order influence (e.g., due to low ice nuclei aerosol frequency). By performing the temporal and spatial correlations between SCFs and different meteorological factors, this study presents specifically the relationship between SCF and different meteorological parameters under different aerosol loadings on a global scale. We find that the SCFs almost decrease with increasing of aerosol loading, and the SCF variation is closely related to the meteorological parameters but their temporal relationship is not stable and varies with the different regions, seasons and isotherm levels. Obviously negative temporal correlations between SCFs versus vertical velocity and relative humidity indicate that the higher vertical velocity and relative humidity the smaller SCFs. However, the patterns of temporal correlation for lower-tropospheric static stability, skin temperature and horizontal wind are relatively more complex than those of vertical velocity and humidity. For example, their close correlations are predominantly located in middle and high latitudes and vary with latitude or surface type. Although these statistical correlations have not been used to establish a certain causal relationship, our results may provide a unique point of view on the phase change of mixed-phase cloud and have potential implications for further improving the parameterization of the cloud phase and determining the climate feedbacks. © Author(s) 2017."
"7004065709;7404830554;57193257133;57201282288;6701799516;55106623200;9249656500;16644465700;7201925326;10739772300;56178229200;35748665500;7403965268;57190728184;7401741559;35421460300;","Lidar detection of high concentrations of ozone and aerosol transported from northeastern Asia over Saga, Japan",2017,"10.5194/acp-17-1865-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012096177&doi=10.5194%2facp-17-1865-2017&partnerID=40&md5=a6ef3fb6f3d99c3d502f7218198df877","To validate products of the Greenhouse gases Observing SATellite (GOSAT), we observed vertical profiles of aerosols, thin cirrus clouds, and tropospheric ozone with a mobile-lidar system that consisted of a two-wavelength (532 and 1064 nm) polarization lidar and a tropospheric ozone differential absorption lidar (DIAL). We used these lidars to make continuous measurements over Saga (33.24° N, 130.29° E) during 20-31 March 2015. High ozone and high aerosol concentrations were observed almost simultaneously in the altitude range 0.5-1.5 km from 03:00 to 20:00 Japan Standard Time (JST) on 22 March 2015. The maximum ozone volume mixing ratio was ∼110 ppbv. The maxima of the aerosol extinction coefficient and optical depth at 532 nm were 1.2 km-1 and 2.1, respectively. Backward trajectory analysis and the simulations by the Model of Aerosol Species IN the Global AtmospheRe (MASINGAR) mk-2 and the Meteorological Research Institute Chemistry-Climate Model, version 2 (MRI-CCM2), indicated that mineral dust particles from the Gobi Desert and an air mass with high ozone and aerosol (mainly sulfate) concentrations that originated from the North China Plain could have been transported over the measurement site within about 2 days. These high ozone and aerosol concentrations impacted surface air quality substantially in the afternoon of 22 March 2015. After some modifications of its physical and chemical parameters, MRI-CCM2 approximately reproduced the high ozone volume mixing ratio. MASINGAR mk-2 successfully predicted high aerosol concentrations, but the predicted peak aerosol optical thickness was about one-third of the observed value. © Author(s) 2017."
"35731251200;26434854300;55481489700;57190072737;56213282800;7005773698;","Laboratory Studies of the Cloud Droplet Activation Properties and Corresponding Chemistry of Saline Playa Dust",2017,"10.1021/acs.est.6b04487","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020405126&doi=10.1021%2facs.est.6b04487&partnerID=40&md5=c29a087416492542916ac2c8f6ccb9e1","Playas emit large quantities of dust that can facilitate the activation of cloud droplets. Despite the potential importance of playa dusts for cloud formation, most climate models assume that all dust is nonhygroscopic; however, measurements are needed to clarify the role of dusts in aerosol-cloud interactions. Here, we report measurements of CCN activation from playa dusts and parameterize these results in terms of both κ-Köhler theory and adsorption activation theory for inclusion in atmospheric models. κ ranged from 0.002 ± 0.001 to 0.818 ± 0.094, whereas Frankel-Halsey-Hill (FHH) adsorption parameters of AFHH = 2.20 ± 0.60 and BFHH = 1.24 ± 0.14 described the water uptake properties of the dusts. Measurements made using aerosol time-of-flight mass spectrometry (ATOFMS) revealed the presence of halite, sodium sulfates, and sodium carbonates that were strongly correlated with κ underscoring the role that mineralogy, including salts, plays in water uptake by dust. Predictions of κ made using bulk chemical techniques generally showed good agreement with measured values. However, several samples were poorly predicted suggesting that chemical heterogeneities as a function of size or chemically distinct particle surfaces can determine the hygroscopicity of playa dusts. Our results further demonstrate the importance of dust in aerosol-cloud interactions. © 2016 American Chemical Society."
"57209178256;35551376300;6603580448;55147025100;7003386805;57202803751;","New-generation NASA Aura Ozone Monitoring Instrument (OMI) volcanic SO2 dataset: Algorithm description, initial results, and continuation with the Suomi-NPP Ozone Mapping and Profiler Suite (OMPS)",2017,"10.5194/amt-10-445-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011950246&doi=10.5194%2famt-10-445-2017&partnerID=40&md5=bec9eecaeb810d74e128f0509313d849","Since the fall of 2004, the Ozone Monitoring Instrument (OMI) has been providing global monitoring of volcanic SO2 emissions, helping to understand their climate impacts and to mitigate aviation hazards. Here we introduce a new-generation OMI volcanic SO2 dataset based on a principal component analysis (PCA) retrieval technique. To reduce retrieval noise and artifacts as seen in the current operational linear fit (LF) algorithm, the new algorithm, OMSO2VOLCANO, uses characteristic features extracted directly from OMI radiances in the spectral fitting, thereby helping to minimize interferences from various geophysical processes (e.g., O3 absorption) and measurement details (e.g., wavelength shift). To solve the problem of low bias for large SO2 total columns in the LF product, the OMSO2VOLCANO algorithm employs a table lookup approach to estimate SO2 Jacobians (i.e., the instrument sensitivity to a perturbation in the SO2 column amount) and iteratively adjusts the spectral fitting window to exclude shorter wavelengths where the SO2 absorption signals are saturated. To first order, the effects of clouds and aerosols are accounted for using a simple Lambertian equivalent reflectivity approach. As with the LF algorithm, OMSO2VOLCANO provides total column retrievals based on a set of predefined SO2 profiles from the lower troposphere to the lower stratosphere, including a new profile peaked at 13 km for plumes in the upper troposphere. Examples given in this study indicate that the new dataset shows significant improvement over the LF product, with at least 50% reduction in retrieval noise over the remote Pacific. For large eruptions such as Kasatochi in 2008 (∼1700 kt total SO2/ and Sierra Negra in 2005 (&gt; 1100DU maximum SO2/, OMSO2VOLCANO generally agrees well with other algorithms that also utilize the full spectral content of satellite measurements, while the LF algorithm tends to underestimate SO2. We also demonstrate that, despite the coarser spatial and spectral resolution of the Suomi National Polar-orbiting Partnership (Suomi-NPP) Ozone Mapping and Profiler Suite (OMPS) instrument, application of the new PCA algorithm to OMPS data produces highly consistent retrievals between OMI and OMPS. The new PCA algorithm is therefore capable of continuing the volcanic SO2 data record well into the future using current and future hyperspectral UV satellite instruments. © Author(s) 2017."
"7004944088;55684491100;6602914876;26029329600;6506848120;7005941217;41661112000;7005960178;6506606807;57188729343;7003323678;57192168375;55895104800;6603089578;7004740995;7103204204;57202518424;55332291100;55682736300;57190128079;6603104382;56244407700;6602516156;22133985200;57190130607;56060986400;57192170187;56463831800;36106033000;55966258500;35122660500;54393349200;15925588200;57192172224;7402838215;57192169899;55801231800;57202531041;6701842515;36515307600;35998927000;56249134600;57191748498;7102936448;35488819200;55469200300;13407563600;14058796400;25923565300;57164786600;56442378900;55730602600;15726759700;6603315547;8083685800;57192172364;57189215242;15926468600;57190209035;56363987000;7003968166;7201423091;7004732931;6603738264;6506126751;","The airborne experiment on natural cirrus and contrail cirrus with the high-Altitude long-range research aircraft halo",2017,"10.1175/BAMS-D-15-00213.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015814304&doi=10.1175%2fBAMS-D-15-00213.1&partnerID=40&md5=b600e02d8324e1b0005458067a4dbcea","The ML-CIRRUS experiment deployed the new research aircraft HALO together with satellites and models to gain new insights into nucleation, life cycle, predictability, and climate impact of natural cirrus and anthropogenic contrail cirrus. © 2017 American Meteorological Society."
"56032511300;55522563200;7003842561;7201839229;55923143300;17347195800;7409080503;56221159300;36182839400;35190489900;","Effects of aerosol on evaporation, freezing and precipitation in a multiple cloud system",2017,"10.1007/s00382-016-3128-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964197183&doi=10.1007%2fs00382-016-3128-1&partnerID=40&md5=46ad491026a22d4e4bb0528172df5a02","Aerosol effects on clouds and precipitation account for a large portion of uncertainties in the prediction of the future course of global hydrologic circulations and climate. As a process of a better understanding of interactions between aerosol, clouds and precipitation, simulations are performed for a mixed-phase convective multiple-cloud system over the tropics. Studies on single-cloud systems have shown that aerosol-induced increases in freezing, associated increases in parcel buoyancy and thus the intensity of clouds (or updrafts) are a main mechanism which controls aerosol–cloud–precipitation interactions in convective clouds. However, in the multiple-cloud system that plays much more important roles in global hydrologic circulations and thus climate than single-cloud systems, aerosol effects on condensation play the most important role in aerosol-induced changes in the intensity of clouds and the effects on freezing play a negligible role in those changes. Aerosol-induced enhancement in evaporation intensifies gust fronts and increases the number of subsequently developing clouds, which leads to the substantial increases in condensation and associated intensity of convection. Although aerosol-induced enhancement in freezing takes part in the increases in condensation by inducing stronger convergence around cloud bottom, the increases in condensation are ~one order of magnitude larger than those in freezing. It is found that while aerosol-induced increases in freezing create intermittent extremely heavy precipitation, aerosol-induced increases in evaporation enhance light and medium precipitation in the multiple-cloud system here. This increase in light and medium precipitation makes it possible that cumulative precipitation increases with increasing aerosol concentration, although the increase is small. It is interesting that the altitude of the maximum of the time- and domain-averaged hydrometeor mass densities is quite robust to increases in aerosol concentration. This is because locations of gust fronts and homogeneous freezing do not vary significantly with changing aerosol concentration and this outweighs aerosol effects on hydrometeor size. © 2016, Springer-Verlag Berlin Heidelberg."
"7404433688;55953758400;36497832500;56514334400;48662342700;","Climatological characteristics of summer precipitation over East Asia measured by TRMM PR: A review",2017,"10.1007/s13351-017-6156-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015749488&doi=10.1007%2fs13351-017-6156-9&partnerID=40&md5=d74c97c3ba6a3653594b8762225f901e","Precipitation is an important indicator of climate change and a critical process in the hydrological cycle, on both the global and regional scales. Methods of precipitation observation and associated analyses are of strategic importance in global climate change research. As the first space-based radar, the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) has been in operation for almost 17 years and has acquired a huge amount of cloud and precipitation data that provide a distinctive view to help expose the nature of cloud and precipitation in the tropics and subtropics. In this paper we review recent advances in summer East Asian precipitation climatology studies based on long-term TRMM PR measurements in the following three aspects: (1) the three-dimensional structure of precipitation, (2) the diurnal variation of precipitation, and (3) the recent precipitation trend. Additionally, some important prospects regarding satellite remote sensing of precipitation and its application in the near future are discussed. © 2017, The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg."
"35192263300;55235064100;35722808700;36615775100;55446625600;55355176000;","A revisit to decadal change of aerosol optical depth and its impact on global radiation over China",2017,"10.1016/j.atmosenv.2016.11.043","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85005975990&doi=10.1016%2fj.atmosenv.2016.11.043&partnerID=40&md5=0863fd1f63dc4fdfb1f8344a9324246f","Global radiation over China decreased between the 1960s and 1990, since when it has remained stable. As the total cloud cover has continued to decrease since the 1960s, variations in aerosols were suggested in previous studies to be the primary cause for variations in global radiation over China. However, the effect of aerosols on global radiation on a decadal scale has not been physically quantified over China. In this study, aerosol optical depth (AOD) data since 1980 are estimated by combining horizontal visibility data at stations in China and AOD observed by the moderate resolution imaging spectroradiometer (MODIS). It is found that the AOD exhibits decadal changes, with two decreasing periods (before the end of 1980s and after 2006) and one increasing period (from 1990 to 2006). With the derived AOD, a clear-sky model is then applied to quantify the role of aerosols in the variations in global radiation over China. The results show that aerosol direct effect cannot fully explain the decadal variations in the global radiation over China between 1980 and 2010, though it has a considerable effect on global radiation climatology. There are significant differences between the trends of clear-sky global radiation impacted by aerosols and those of all-sky global radiation impacted by aerosols and clouds, and the correlation coefficient for the comparison is very low. Therefore, the variations in all-sky global radiation over China are likely to be due to changes in cloud properties and to interactions between clouds and aerosols. © 2016 Elsevier Ltd"
"7201504886;56324515500;56270311300;7402786837;56154540200;57193157387;57193073844;8696069500;","MACv2-SP: A parameterization of anthropogenic aerosol optical properties and an associated Twomey effect for use in CMIP6",2017,"10.5194/gmd-10-433-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011263995&doi=10.5194%2fgmd-10-433-2017&partnerID=40&md5=ac004681fe90c4c54abc2f12f8cd3b58","A simple plume implementation of the second version (v2) of the Max Planck Institute Aerosol Climatology, MACv2-SP, is described. MACv2-SP provides a prescription of anthropogenic aerosol optical properties and an associated Twomey effect. It was created to provide a harmonized description of post-1850 anthropogenic aerosol radiative forcing for climate modeling studies. MACv2-SP has been designed to be easy to implement, change and use, and thereby enable studies exploring the climatic effects of different patterns of aerosol radiative forcing, including a Twomey effect. MACv2-SP is formulated in terms of nine spatial plumes associated with different major anthropogenic source regions. The shape of the plumes is fit to the Max Planck Institute Aerosol Climatology, version 2, whose present-day (2005) distribution is anchored by surface-based observations. Two types of plumes are considered: one predominantly associated with biomass burning, the other with industrial emissions. These differ in the prescription of their annual cycle and in their optical properties, thereby implicitly accounting for different contributions of absorbing aerosol to the different plumes. A Twomey effect for each plume is prescribed as a change in the host model's background cloud-droplet population density using relationships derived from satellite data. Year-to-year variations in the amplitude of the plumes over the historical period (1850-2016) are derived by scaling the plumes with associated national emission sources of SO2 and NH3. Experiments using MACv2-SP are performed with the Max Planck Institute Earth System Model. The globally and annually averaged instantaneous and effective aerosol radiative forcings are estimated to be -0.6 and -0.5 W m-2, respectively. Forcing from aerosol-cloud interactions (the Twomey effect) offsets the reduction of clear-sky forcing by clouds, so that the net effect of clouds on the aerosol forcing is small; hence, the clear-sky forcing, which is more readily measurable, provides a good estimate of the total aerosol forcing. © Author(s) 2017."
"55711594800;7201897043;","The impact of an extreme case of irrigation on the southeastern United States climate",2017,"10.1007/s00382-016-3144-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84965069029&doi=10.1007%2fs00382-016-3144-1&partnerID=40&md5=f30a150be45696cab14cf342ffa5b36a","The impacts of irrigation on southeast United States diurnal climate are investigated using simulations from a regional climate model. An extreme case is assumed, wherein irrigation is set to 100 % of field capacity over the growing season of May through October. Irrigation is applied to the root zone layers of 10–40 and 40–100 cm soil layers only. It is found that in this regime there is a pronounced decrease in monthly averaged temperatures in irrigated regions across all months. In non-irrigated areas a slight warming is simulated. Diurnal maximum temperatures in irrigated areas warm, while diurnal minimum temperatures cool. The daytime warming is attributed to an increase in shortwave flux at the surface owing to diminished low cloud cover. Nighttime and daily mean cooling result as a consequence repartitioning of energy into latent heat flux over sensible heat flux, and of a higher net downward ground heat flux. Excess heat is transported into the deep soil layer, preventing a rapidly intensifying positive feedback loop. Both diurnal and monthly average precipitations are reduced over irrigated areas at a magnitude and spatial pattern similar to one another. Due to the excess moisture availability, evaporation is seen to increase, but this is nearly balanced by a corresponding reduction in sensible heat flux. Concomitant with additional moisture availability is an increase in both transient and stationary moisture flux convergences. However, despite the increase, there is a large-scale stabilization of the atmosphere stemming from a cooled surface. © 2016, Springer-Verlag Berlin Heidelberg."
"55803933000;7403019018;55890961500;26433171500;22935158900;7101860638;7003298514;","Vegetation phenology gradients along the west and east coasts of Greenland from 2001 to 2015",2017,"10.1007/s13280-016-0866-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010443390&doi=10.1007%2fs13280-016-0866-6&partnerID=40&md5=7c276c61d655d1a0089bf16673e8c08c","The objective of this paper is to characterize the spatiotemporal variations of vegetation phenology along latitudinal and altitudinal gradients in Greenland, and to examine local and regional climatic drivers. Time-series from the Moderate Resolution Imaging Spectroradiometer (MODIS) were analyzed to obtain various phenological metrics for the period 2001–2015. MODIS-derived land surface temperatures were corrected for the sampling biases caused by cloud cover. Results indicate significant differences between West and East Greenland, in terms of both observed phenology during the study period, as well as the climatic response. The date of the start of season (SOS) was significantly earlier (24 days), length of season longer (25 days), and time-integrated NDVI higher in West Greenland. The sea ice concentration during May was found to have a significant effect on the date of the SOS only in West Greenland, with the strongest linkage detected in mid-western parts of Greenland. © 2017, The Author(s)."
"22935158900;55547727700;26433171500;25624257300;7403019018;6602506180;","Spatiotemporal variability in surface energy balance across tundra, snow and ice in Greenland",2017,"10.1007/s13280-016-0867-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010289441&doi=10.1007%2fs13280-016-0867-5&partnerID=40&md5=a78bfc84a21fdbf79171027b66fd0b1f","The surface energy balance (SEB) is essential for understanding the coupled cryosphere–atmosphere system in the Arctic. In this study, we investigate the spatiotemporal variability in SEB across tundra, snow and ice. During the snow-free period, the main energy sink for ice sites is surface melt. For tundra, energy is used for sensible and latent heat flux and soil heat flux leading to permafrost thaw. Longer snow-free period increases melting of the Greenland Ice Sheet and glaciers and may promote tundra permafrost thaw. During winter, clouds have a warming effect across surface types whereas during summer clouds have a cooling effect over tundra and a warming effect over ice, reflecting the spatial variation in albedo. The complex interactions between factors affecting SEB across surface types remain a challenge for understanding current and future conditions. Extended monitoring activities coupled with modelling efforts are essential for assessing the impact of warming in the Arctic. © 2017, The Author(s)."
"55819549500;57188837293;16506458200;15050523700;7404178566;36006968000;","Seminal role of stratiform clouds in large-scale aggregation of tropical rain in boreal summer monsoon intraseasonal oscillations",2017,"10.1007/s00382-016-3124-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963769987&doi=10.1007%2fs00382-016-3124-5&partnerID=40&md5=458d25a69aa326ca5364e78dbad33da7","Modification of the vertical structure of non-adiabatic heating by significant abundance of the stratiform rain in the tropics has been known to influence the large-scale circulation. However, the role of the stratiform rain on the space–time evolution of the observed Boreal summer monsoon intraseasonal oscillations (MISO) has so far been ignored. In the present study, we unravel a feedback mechanism through which the stratiform component of the rain leads to aggregation (organization) of rain on the MISO scale, making it an indispensable component of the MISO evolution dynamics. Using TRMM 3A25 monthly mean data (between 1998 and 2013), the ratio between convective and stratiform rain (RCS) is shown to be strongly related to the total rainfall. Further, composites of rainfall and circulation anomalies corresponding to high (low) values of RCS over the Central India or over the Equatorial Indian Ocean show spatial structures remarkably similar to that associated with the MISOs. Analyzing lead–lag relationship between the convective rain, the stratiform rain and the large scale moisture convergence with respect to peak active (break) spells from daily modern era retrospective-analysis for research and applications data, we unravel that the initial isolated convective elements spawn the stratiform rain which in turn modifies the vertical distribution of heating and leads to stronger large scale moisture convergence thereby producing more convective elements and more stratiform rain ultimately leading to aggregation of rain on the MISO scale. Our finding indicates that large and persisting systematic biases in simulating the summer monsoon rainfall over the Asian monsoon region by climate models are likely to be related to the systematic biases in simulating the MISOs which in turn are related to the serious underestimation of stratiform rain in most climate models. © 2016, Springer-Verlag Berlin Heidelberg."
"56374442600;56446005400;56649377700;56051686100;57217758616;57205085102;55545335600;","Chemical and physical properties of biomass burning aerosols and their CCN activity: A case study in Beijing, China",2017,"10.1016/j.scitotenv.2016.11.112","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028250478&doi=10.1016%2fj.scitotenv.2016.11.112&partnerID=40&md5=f455877e329d25709c1ddadb686e1c2b","Biomass burning emits large amounts of both trace gases and particles into the atmosphere. It plays a profound role in regional air quality and climate change. In the present study, an intensive campaign was carried out at an urban site in Beijing, China, in June 2014, which covered the winter wheat harvest season over the North China Plain (NCP). Meanwhile, two evident biomass-burning events were observed. A clear burst in ultrafine particles (below 100 nm in diameter, PM1) and subsequent particle growth took place during the events. With the growth of the ultrafine particles, the organic fraction of PM1 increased significantly. The ratio of oxygen to carbon (O:C), which had an average value of 0.23 ± 0.04, did not show an obvious enhancement, indicating that a significant chemical aging process of the biomass-burning aerosols was not observed during the course of events. This finding might have been due to the fact that the biomass-burning events occurred in the late afternoon and grew during the nighttime, which is associated with a low atmospheric oxidation capacity. On average, organics and black carbon (BC) were dominant in the biomass-burning aerosols, accounting for 60 ± 10% and 18 ± 3% of PM1. The high organic and BC fractions led to a significant suppression of particle hygroscopicity. Comparisons among hygroscopicity tandem differential mobility analyzer (HTDMA)-derived, cloud condensation nuclei counter (CCNc)-derived, and aerosol mass spectrometer-based hygroscopicity parameter (κ) values were consistent. The mean κ values of biomass-burning aerosols derived from both HTDMA and CCNc measurements were approximately 0.1, regardless of the particle size, indicating that the biomass-burning aerosols were less active. The burst in particle count during the biomass-burning events resulted in an increased number of cloud condensation nuclei (CCN) at supersaturation (SS) = 0.2–0.8%. © 2016 Elsevier B.V."
"56955761800;55081793600;36660575800;55896877200;6506095035;","An improvement in mass flux convective parameterizations and its impact on seasonal simulations using a coupled model",2017,"10.1007/s00704-015-1668-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84946761428&doi=10.1007%2fs00704-015-1668-7&partnerID=40&md5=f9b24158e7fb3bd8542e7bbc70753e2a","A new closure and a modified detrainment for the simplified Arakawa–Schubert (SAS) cumulus parameterization scheme are proposed. In the modified convective scheme which is named as King Abdulaziz University (KAU) scheme, the closure depends on both the buoyancy force and the environment mean relative humidity. A lateral entrainment rate varying with environment relative humidity is proposed and tends to suppress convection in a dry atmosphere. The detrainment rate also varies with environment relative humidity. The KAU scheme has been tested in a single column model (SCM) and implemented in a coupled global climate model (CGCM). Increased coupling between environment and clouds in the KAU scheme results in improved sensitivity of the depth and strength of convection to environmental humidity compared to the original SAS scheme. The new scheme improves precipitation simulation with better representations of moisture and temperature especially during suppressed convection periods. The KAU scheme implemented in the Seoul National University (SNU) CGCM shows improved precipitation over the tropics. The simulated precipitation pattern over the Arabian Peninsula and Northeast African region is also improved. © 2015, Springer-Verlag Wien."
"35223783100;56974294800;7003507673;56578557000;7003942283;","Novel aerosol analysis approach for characterization of nanoparticulate matter in snow",2017,"10.1007/s11356-016-8199-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003945024&doi=10.1007%2fs11356-016-8199-3&partnerID=40&md5=290f44ee70737ccba7485a6e3815ea95","Tropospheric aerosols are involved in several key atmospheric processes: from ice nucleation, cloud formation, and precipitation to weather and climate. The impact of aerosols on these atmospheric processes depends on the chemical and physical characteristics of aerosol particles, and these characteristics are still largely uncertain. In this study, we developed a system for processing and aerosolization of melted snow in particle-free air, coupled with a real-time measurement of aerosol size distributions. The newly developed technique involves bringing snow-borne particles into an airborne state, which enables application of high-resolution aerosol analysis and sampling techniques. This novel analytical approach was compared to a variety of complementary existing analytical methods as applied for characterization of snow samples from remote sites in Alert (Canada) and Barrow (USA), as well as urban Montreal (Canada). The dry aerosol measurements indicated a higher abundance of particles of all sizes, and the 30 nm size dominated in aerosol size distributions for the Montreal samples, closely followed by Barrow, with about 30% fewer 30 nm particles, and about four times lower 30 nm particle abundance in Alert samples, where 15 nm particles were most abundant instead. The aerosolization technique, used together with nanoparticle tracking analysis and electron microscopy, allowed measurement of a wide size range of snow-borne particles in various environmental snow samples. Here, we discuss the application of the new technique to achieve better physicochemical understanding of atmospheric and snow processes. The results showed high sensitivity and reduction of particle aggregation, as well as the ability to measure a high-resolution snow-borne particle size distribution, including nanoparticulate matter in the range of 10 to 100 nm. © 2016, Springer-Verlag Berlin Heidelberg."
"56267602600;7201519079;24461654300;","Characteristics of the precipitation recycling ratio and its relationship with regional precipitation in China",2017,"10.1007/s00704-015-1645-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944578769&doi=10.1007%2fs00704-015-1645-1&partnerID=40&md5=44879773db9ea4ef4a5ccba0b1fa0637","A dynamic recycling model (DRM) with an analytical moisture trajectory tracking method, together with Japan Meteorological Agency 25-year reanalysis data, is used to study the regional precipitation recycling process across China, by calculating the regional recycling ratio (ρr) at the daily time scale during 1979–2010. The distribution of ρr shows that, in western China, especially the Tibetan Plateau and its surrounding areas, precipitation is strongly dependent on the recycling process associated with regional evaporation. In Southeast China, however, the contribution from the recycling processes is much smaller due to the influence of the summer monsoon. A precipitation threshold value of about 4 mm/day is obtained from detailed analysis of both extreme and all-range ρr years. According to this threshold, China is classified into three types of sub-regions: low-precipitation sub-regions (mainly in the northwest), high-precipitation sub-regions (mainly in the south), and medium-precipitation sub-regions (mainly in the northeast). It is found that ρr correlates positively with precipitation, as well as convective precipitation (PCP) and large-scale precipitation (PLP) in the low-precipitation sub-regions. However, negative ρr ∼ PLP correlations are found in the high-precipitation sub-regions and nonsignificant correlations exist in the medium-precipitation sub-regions. As PCP is mainly locally generated due to mid-latitude mesoscale systems and the cumulus parameterization used in producing the reanalysis, the recycling ratio positively correlates to the ratio PCP/PLP in almost all sub-regions, particularly in the Tibetan Plateau and its surrounding areas. The correlation between radiation flux and ρr suggests more net radiation supports more evaporation and higher ρr, especially in the high-precipitation sub-regions. The influence of clouds on shortwave radiation is crucial, since evaporation is suppressed when the amount of cloudiness increases, especially in the high-precipitation sub-regions. Together with the consideration of soil moisture, it can be inferred that limited soil moisture inhibits evaporation in the low-precipitation sub-regions, while the energy or radiation is the dominant factor controlling evaporation in the high-precipitation sub-regions. © 2015, Springer-Verlag Wien."
"57208579037;7006493632;","On the contrasting decadal changes of diurnal surface temperature range between the Tibetan Plateau and southeastern China during the 1980s–2000s",2017,"10.1007/s00376-016-6077-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008929535&doi=10.1007%2fs00376-016-6077-z&partnerID=40&md5=adfc5887e79ceb0b24d430d46fa2ff22","The diurnal surface temperature range (DTR) has become significantly smaller over the Tibetan Plateau (TP) but larger in southeastern China, despite the daily mean surface temperature having increased steadily in both areas during recent decades. Based on ERA-Interim reanalysis data covering 1979–2012, this study shows that the weakened DTR over TP is caused by stronger warming of daily minimum surface temperature (Tmin) and a weak cooling of the daily maximum surface temperature (Tmax); meanwhile, the enhanced DTR over southeastern China is mainly associated with a relatively stronger/weaker warming of Tmax/Tmin. A further quantitative analysis of DTR changes through a process-based decomposition method—the Coupled Surface–Atmosphere Climate Feedback Response Analysis Method (CFRAM)—indicates that changes in radiative processes are mainly responsible for the decreased DTR over the TP. In particular, the increased low-level cloud cover tends to induce the radiative cooling/warming during daytime/nighttime, and the increased water vapor helps to decrease the DTR through the stronger radiative warming during nighttime than daytime. Contributions from the changes in all radiative processes (over −2°C) are compensated for by those from the stronger decreased surface sensible heat flux during daytime than during nighttime (approximately 2.5°C), but are co-contributed by the changes in atmospheric dynamics (approximately −0.4°C) and the stronger increased latent heat flux during daytime (approximately −0.8°C). In contrast, the increased DTR over southeastern China is mainly contributed by the changes in cloud, water vapor and atmospheric dynamics. The changes in surface heat fluxes have resulted in a decrease in DTR over southeastern China. © 2017, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg."
"55216722000;57204521929;35746716000;35756335100;","The urban cool island phenomenon in a high-rise high-density city and its mechanisms",2017,"10.1002/joc.4747","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971449985&doi=10.1002%2fjoc.4747&partnerID=40&md5=787f4eed7cafa255e6517b7873c92f5e","The urban heat island (UHI) phenomenon has been studied extensively, but there are relatively fewer reports on the so-called urban cool island (UCI) phenomenon. We reveal here that the UCI phenomenon exists in Hong Kong during the day and is associated with the UHI at night under all wind and cloud conditions. The possible mechanisms for the UCI phenomenon in such a high-rise compact city have been discovered using a lumped urban air temperature model. A new concept of urban cool island degree hours (UCIdh) to measure the UCI intensity and duration is proposed. Our analyses reveal that when anthropogenic heat is small or absent, a high-rise, and high-density city experiences a significant daytime UCI effect. This is explained by an intensified heat storage capacity and the reduced solar radiation gain of urban surfaces. However, if anthropogenic heat in the urban area increases further, the UCI phenomenon still exists; yet, UCIdh decrease dramatically in a high-rise compact city. In a low-rise, low-density city, the UCI phenomenon also occurs when there is no anthropogenic heat, but easily disappears when there is little anthropogenic heat, and the UHI phenomenon dominates. This probably explains why the UHI phenomenon is often observed, but the UCI phenomenon is rarely observed. The co-existence of urban heat/cool island phenomena implies reduction of the daily temperature range in such cities, and its dependence on urban morphology also implies that urban morphology can be used to control the urban thermal environment. © 2016 Royal Meteorological Society"
"56672877100;23994515200;33167514000;","Modeling multidecadal surface water inundation dynamics and key drivers on large river basin scale using multiple time series of Earth-observation and river flow data",2017,"10.1002/2016WR019858","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012969689&doi=10.1002%2f2016WR019858&partnerID=40&md5=54a3c74e90e42e8d767b3e80c8602ab2","Periodically inundated floodplain areas are hot spots of biodiversity and provide a broad range of ecosystem services but have suffered alarming declines in recent history. Despite their importance, their long-term surface water (SW) dynamics and hydroclimatic drivers remain poorly quantified on continental scales. In this study, we used a 26 year time series of Landsat-derived SW maps in combination with river flow data from 68 gauges and spatial time series of rainfall, evapotranspiration and soil moisture to statistically model SW dynamics as a function of key drivers across Australia's Murray-Darling Basin (∼1 million km2). We fitted generalized additive models for 18,521 individual modeling units made up of 10 × 10 km grid cells, each split into floodplain, floodplain-lake, and nonfloodplain area. Average goodness of fit of models was high across floodplains and floodplain-lakes (r2 &gt; 0.65), which were primarily driven by river flow, and was lower for nonfloodplain areas (r2 &gt; 0.24), which were primarily driven by rainfall. Local climate conditions were more relevant for SW dynamics in the northern compared to the southern basin and had the highest influence in the least regulated and most extended floodplains. We further applied the models of two contrasting floodplain areas to predict SW extents of cloud-affected time steps in the Landsat series during the large 2010 floods with high validated accuracy (r2 &gt; 0.97). Our framework is applicable to other complex river basins across the world and enables a more detailed quantification of large floods and drivers of SW dynamics compared to existing methods. © 2017. American Geophysical Union. All Rights Reserved."
"57192385008;57214672257;8934029200;","Impact of anomalous forest fire on aerosol radiative forcing and snow cover over Himalayan region",2017,"10.1016/j.atmosenv.2016.11.061","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85005943962&doi=10.1016%2fj.atmosenv.2016.11.061&partnerID=40&md5=91bade9851a21218901b64dafee8a677","Forest fires are very common in tropical region during February–May months and are known to have significant impact on ecosystem dynamics. Moreover, aerosols emitted from these burning activities significantly modulate the Earth's radiation budget. In present study, we investigated the anomalous forest fire events and their impact on atmospheric radiation budget and glaciated snow cover over the Himalayan region. We used multiple dataset derived from satellites [Moderate Resolution Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO)] and reanalysis models [Global Fire Assimilation System (GFAS), Second Modern-Era Retrospective analysis for Research and Application (MERRA-2) and ERA-interim] to evaluate the effect of biomass burning aerosols on radiation budget. April 2016 is associated with anomalous fire activities over lower Himalayan region in the last fourteen years (2003–2016). The model estimated organic carbon (OC) and black carbon (BC) emission reaches up to ∼3 × 104 and ∼2 × 103 μg/m2/day, respectively during the biomass burning period of April 2016. The meteorological data analysis accompanied with CALIOP aerosol vertical profile shows that these carbonaceous aerosols could reach up to ∼5–7 km altitude and could be transported towards glaciated region of upper Himalayas. The large amount of BC/OC from biomass burning significantly modulates the atmospheric radiation budget. The estimated columnar heating rate shows that these carbonaceous aerosols could heat up the atmosphere by ∼0.04–0.06 K/day in April-2016 with respect to non-burning period (2015). The glaciated snow cover fractions are found to be decreasing by ∼5–20% in 2016 as compared to long term mean (2003–2016). The combined analyses of various climatic factors, fires and associated BC emissions show that the observed snow cover decrease could be results of increased surface/atmospheric temperature due to combined effect of large scale climatic changes and BC absorption. Our results suggest that biomass burning can have significant effects on the Himalayan region, particularly in view of its importance in hydrological cycle and ecosystem. © 2016 Elsevier Ltd"
"55913183200;7402989545;7403590757;","The asymmetric effects of El Niño and La Niña on the East Asian winter monsoon and their simulation by CMIP5 atmospheric models",2017,"10.1007/s13351-017-6095-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015757197&doi=10.1007%2fs13351-017-6095-5&partnerID=40&md5=2f705b6f12bafbd44c888fc9eb00b991","El Niño–Southern Oscillation (ENSO) events significantly affect the year-by-year variations of the East Asian winter monsoon (EAWM). However, the effect of La Niña events on the EAWM is not a mirror image of that of El Niño events. Although the EAWM becomes generally weaker during El Niño events and stronger during La Niña winters, the enhanced precipitation over the southeastern China and warmer surface air temperature along the East Asian coastline during El Niño years are more significant. These asymmetric effects are caused by the asymmetric longitudinal positions of the western North Pacific (WNP) anticyclone during El Niño events and the WNP cyclone during La Niña events; specifically, the center of the WNP cyclone during La Niña events is westward-shifted relative to its El Niño counterpart. This central-position shift results from the longitudinal shift of remote El Niño and La Niña anomalous heating, and asymmetry in the amplitude of local sea surface temperature anomalies over the WNP. However, such asymmetric effects of ENSO on the EAWM are barely reproduced by the atmospheric models of Phase 5 of the Coupled Model Intercomparison Project (CMIP5), although the spatial patterns of anomalous circulations are reasonably reproduced. The major limitation of the CMIP5 models is an overestimation of the anomalous WNP anticyclone/cyclone, which leads to stronger EAWM rainfall responses. The overestimated latent heat flux anomalies near the South China Sea and the northern WNP might be a key factor behind the overestimated anomalous circulations. © 2017, The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg."
"55437763600;7003494809;7402534046;6603785931;","Phenology from Landsat when data is scarce: Using MODIS and Dynamic Time-Warping to combine multi-year Landsat imagery to derive annual phenology curves",2017,"10.1016/j.jag.2016.09.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018195485&doi=10.1016%2fj.jag.2016.09.005&partnerID=40&md5=09ad43ec261f9a27da5f90b7bbbe3401","Green-leaf phenology describes the development of vegetation throughout a growing season and greatly affects the interaction between climate and the biosphere. Remote sensing is a valuable tool to characterize phenology over large areas but doing at fine- to medium resolution (e.g., with Landsat data) is difficult because of low numbers of cloud-free images in a single year. One way to overcome data availability limitations is to merge multi-year imagery into one time series, but this requires accounting for phenological differences among years. Here we present a new approach that employed a time series of a MODIS vegetation index data to quantify interannual differences in phenology, and Dynamic Time Warping (DTW) to re-align multi-year Landsat images to a common phenology that eliminates year-to-year phenological differences. This allowed us to estimate annual phenology curves from Landsat between 2002 and 2012 from which we extracted key phenological dates in a Monte-Carlo simulation design, including green-up (GU), start-of-season (SoS), maturity (Mat), senescence (Sen), end-of-season (EoS) and dormancy (Dorm). We tested our approach in eight locations across the United States that represented forests of different types and without signs of recent forest disturbance. We compared Landsat-based phenological transition dates to those derived from MODIS and ground-based camera data from the PhenoCam-network. The Landsat and MODIS comparison showed strong agreement. Dates of green-up, start-of-season and maturity were highly correlated (r 0.86-0.95), as were senescence and end-of-season dates (r > 0.85) and dormancy (r > 0.75). Agreement between the Landsat and PhenoCam was generally lower, but correlation coefficients still exceeded 0.8 for all dates. In addition, because of the high data density in the new Landsat time series, the confidence intervals of the estimated keydates were substantially lower than in case of MODIS and PhenoCam. Our study thus suggests that by exploiting multi-year Landsat imagery and calibrating it with MODIS data it is possible to describe green-leaf phenology at much finer spatial resolution than previously possible, highlighting the potential for fine scale phenology maps using the rich Landsat data archive over large areas. © 2016 Elsevier B.V."
"55968364300;56789763900;55241984000;57149740600;57190953520;57193137851;7004715270;7005968859;8586682800;7005773698;","Transport of pollution to a remote coastal site during gap flow from California's interior: Impacts on aerosol composition, clouds, and radiative balance",2017,"10.5194/acp-17-1491-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011094175&doi=10.5194%2facp-17-1491-2017&partnerID=40&md5=97e43e9012496b5a32adb0df1417c385","During the CalWater 2015 field campaign, ground-level observations of aerosol size, concentration, chemical composition, and cloud activity were made at Bodega Bay, CA, on the remote California coast. A strong anthropogenic influence on air quality, aerosol physicochemical properties, and cloud activity was observed at Bodega Bay during periods with special weather conditions, known as Petaluma Gap flow, in which air from California's interior is transported to the coast. This study applies a diverse set of chemical, cloud microphysical, and meteorological measurements to the Petaluma Gap flow phenomenon for the first time. It is demonstrated that the sudden and often dramatic change in aerosol properties is strongly related to regional meteorology and anthropogenically influenced chemical processes in California's Central Valley. In addition, it is demonstrated that the change in air mass properties from those typical of a remote marine environment to properties of a continental regime has the potential to impact atmospheric radiative balance and cloud formation in ways that must be accounted for in regional climate simulations."
"55682751100;8084443000;56427637700;56427880900;6701818843;26532031800;35593636200;35578922100;7006595513;6602533657;7004015298;","CCN production by new particle formation in the free troposphere",2017,"10.5194/acp-17-1529-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011279400&doi=10.5194%2facp-17-1529-2017&partnerID=40&md5=85ea2210c2238433b1c21f1c0a3a363f","Global models predict that new particle formation (NPF) is, in some environments, responsible for a substantial fraction of the total atmospheric particle number concentration and subsequently contributes significantly to cloud condensation nuclei (CCN) concentrations. NPF events were frequently observed at the highest atmospheric observatory in the world, on Chacaltaya (5240ma.s.l.), Bolivia. The present study focuses on the impact of NPF on CCN population. Neutral cluster and Air Ion Spectrometer and mobility particle size spectrometer measurements were simultaneously used to follow the growth of particles from cluster sizes down to ∼2 nm up to CCN threshold sizes set to 50, 80 and 100 nm. Using measurements performed between 1 January and 31 December 2012, we found that 61% of the 94 analysed events showed a clear particle growth and significant enhancement of the CCN-relevant particle number concentration. We evaluated the contribution of NPF, relative to the transport and growth of pre-existing particles, to CCN size. The averaged production of 50 nm particles during those events was 5072, and 1481 cm-3 for 100 nm particles, with a larger contribution of NPF compared to transport, especially during the wet season. The data set was further segregated into boundary layer (BL) and free troposphere (FT) conditions at the site. The NPF frequency of occurrence was higher in the BL (48 %) compared to the FT (39 %). Particle condensational growth was more frequently observed for events initiated in the FT, but on average faster for those initiated in the BL, when the amount of condensable species was most probably larger. As a result, the potential to form new CCN was higher for events initiated in the BL (67% against 53% in the FT). In contrast, higher CCN number concentration increases were found when the NPF process initially occurred in the FT, under less polluted conditions. This work highlights the competition between particle growth and the removal of freshly nucleated particles by coagulation processes. The results support model predictions which suggest that NPF is an effective source of CCN in some environments, and thus may influence regional climate through cloud-related radiative processes. © Author(s) 2017."
"57193170261;55581675600;35227762400;55173596300;57205307947;35611334800;6602600408;","Assessment of simulated aerosol effective radiative forcings in the terrestrial spectrum",2017,"10.1002/2016GL071975","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011343414&doi=10.1002%2f2016GL071975&partnerID=40&md5=57f5a55a84f48023175214a15e24e9e0","In its fifth assessment report (AR5), the Intergovernmental Panel on Climate Change provides a best estimate of the effective radiative forcing (ERF) due to anthropogenic aerosol at −0.9 W m−2. This value is considerably weaker than the estimate of −1.2 W m−2 in AR4. A part of the difference can be explained by an offset of +0.2 W m−2 which AR5 added to all published estimates that only considered the solar spectrum, in order to account for adjustments in the terrestrial spectrum. We find that, in the CMIP5 multimodel median, the ERF in the terrestrial spectrum is small, unless microphysical effects on ice- and mixed-phase clouds are parameterized. In the latter case it is large but accompanied by a very strong ERF in the solar spectrum. The total adjustments can be separated into microphysical adjustments (aerosol “effects”) and thermodynamic adjustments. Using a kernel technique, we quantify the latter and find that the rapid thermodynamic adjustments of water vapor and temperature profiles are small. Observation-based constraints on these model results are urgently needed. ©2017. American Geophysical Union. All Rights Reserved."
"24472110700;7003875148;","Clouds, warm air, and a climate cooling signal over the summer Arctic",2017,"10.1002/2016GL071959","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010533631&doi=10.1002%2f2016GL071959&partnerID=40&md5=35a9709c13dfe3683c579772e5c08ab0","While the atmospheric greenhouse effect always results in a warming at the surface, outgoing longwave radiation (OLR) to space always represents a cooling. During events of heat and moisture advection into the Arctic, increases in tropospheric temperature and moisture impact clouds, in turn impacting longwave (LW) radiation. State-of-the-art satellite measurements and atmospheric reanalysis consistently reveal an enhancement of summer Arctic monthly OLR cooling ranging 1.5–4 W m−2 during months with anomalously high thermodynamic advection. This cooling anomaly is found to be of the same magnitude or slightly larger than associated downwelling LW surface warming anomalies. We identify a relationship between large-scale circulation variability and changing cloud properties permitting LW radiation at both the surface and top of the atmosphere to respond to variability in atmospheric thermodynamics. Driven by anomalous advection of warm air, the corresponding enhanced OLR cooling signal on monthly time scales represents an important buffer to regional Arctic warming. ©2017. American Geophysical Union. All Rights Reserved."
"55938109300;36661106500;6508026916;39361670300;","Biomass burning aerosol impact on surface winds during the 2010 Russian heat wave",2017,"10.1002/2016GL071484","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010629691&doi=10.1002%2f2016GL071484&partnerID=40&md5=2ea4d225fa6a58dce704ad4f213ab240","This paper elucidates the impact of biomass burning aerosols (BB) on surface winds for the Russian fires episode during 25 July to 15 August 2010. The methodology consists of three Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) simulations over Europe differing in the inclusion (or not) of aerosol-radiation and aerosol-cloud interactions. The presence of BB reduces the 10 m wind speed over Russia during this fire event by 0.2 m s−1 (10%). Aerosol interactions imply a decrease of the shortwave downwelling radiation at the surface leading to a reduction of the 2 m temperature. This decrease reduces the turbulence flux, developing a more stable planetary boundary layer. Moreover, cooling favors an increase of the surface pressure over Russian area and also it extends nearby northern Europe. ©2016. American Geophysical Union. All Rights Reserved."
"56663169300;24821044400;6602922582;6701820813;","Reduction of monsoon rainfall in response to past and future land use and land cover changes",2017,"10.1002/2016GL070663","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011573335&doi=10.1002%2f2016GL070663&partnerID=40&md5=d276150e2274169c6d619af4d15e017f","Land use and land cover changes (LULCC) can have significant biophysical impacts on regional precipitation, including monsoon rainfall. Using global simulations with and without LULCC from five general circulation models, under the Representative Concentration Pathway 8.5 scenario, we find that future LULCC significantly reduce monsoon precipitation in at least four (out of eight) monsoon regions. While monsoon rainfalls are likely to intensify under future global warming, we estimate that biophysical effects of LULCC substantially weaken future projections of monsoons' rainfall by 9% (Indian region), 12% (East Asian), 32% (South African), and 41% (North African), with an average of ~ 30% for projections across the global monsoon region. A similar strong contribution is found for biophysical effects of past LULCC to monsoon rainfall changes since the preindustrial period. Rather than remote effects, local land-atmosphere interactions, implying a decrease in evapotranspiration, soil moisture, and clouds along with more anticyclonic conditions, could explain this reduction in monsoon rainfall. ©2016. American Geophysical Union. All Rights Reserved."
"57203809453;57192273006;9244992800;56254969000;","Attribution of the local Hadley cell widening in the Southern Hemisphere",2017,"10.1002/2016GL072353","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010992235&doi=10.1002%2f2016GL072353&partnerID=40&md5=17dd8d1cc2afe93f7f7c77c4887de342","This study conducts an attribution analysis of long-term changes in the southern edge of the local Hadley cell (HC) during austral summer for the past three decades (1979–2009). The southern edges of the local overturning circulations (local HC) are defined as the latitudes of maximum sea level pressure in the Southern Hemisphere subtropics, and the long-term variations of local HC edges from multireanalyses are compared with those from Coupled Model Intercomparison Project Phase 5 (CMIP5) multimodel simulations by using the optimal fingerprinting technique. The observed local HC exhibits a poleward expansion in the Atlantic and Indian Ocean regions, which is successfully reproduced by the CMIP5 models including anthropogenic forcing (ANT) but with a weaker amplitude. The detection analyses further show that ANT signals are detected robustly in both Atlantic and Indian HC trends. More importantly, anthropogenic forcings other than greenhouse gas forcing are found to be clearly detected in isolation, indicating a possible attribution of the observed local HC widening over these regions to stratospheric ozone depletion. ©2017. American Geophysical Union. All Rights Reserved."
"56463153400;23065650200;","Growth of ice particle mass and projected area during riming",2017,"10.5194/acp-17-1241-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011101190&doi=10.5194%2facp-17-1241-2017&partnerID=40&md5=0510e44b91405fd556c7340bf937a133","There is a long-standing challenge in cloud and climate models to simulate the process of ice particle riming realistically, partly due to the unrealistic parameterization of the growth of ice particle mass (m) and projected area (A) during riming. This study addresses this problem, utilizing ground-based measurements of m and ice particle maximum dimension (D) as well as theory to formulate simple expressions describing the dependence of m and A on riming. It was observed that β in the m-D power law m = αDβ appears independent of riming during the phase 1 (before the formation of graupel), with α accounting for the ice particle mass increase due to riming. This semi-empirical approach accounts for the degree of riming and renders a gradual and smooth ice particle growth process from unrimed ice particles to graupel, and thus avoids discontinuities in m and A during accretional growth. Once the graupel with quasispherical shape forms, D increases with an increase in m and A (phase 2 of riming). The treatment for riming is explicit, and includes the parameterization of the ice crystal-cloud droplet collision efficiency (Ec) for hexagonal columns and plates using hydrodynamic theory. In particular, Ec for cloud droplet diameters less than 10 μm are estimated, and under some conditions observed in mixed-phase clouds, these droplets can account for roughly half of the mass growth rate from riming. These physically meaningful yet simple methods can be used in models to improve the riming process. © Author(s) 2017."
"48662824200;7006783796;55747131500;8719703500;24759591600;6506234624;","Global clear-sky surface skin temperature from multiple satellites using a single-channel algorithm with angular anisotropy corrections",2017,"10.5194/amt-10-351-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011049855&doi=10.5194%2famt-10-351-2017&partnerID=40&md5=ca3f1aac838e08664dc80a0070a30cdd","Surface skin temperature (Ts) is an important parameter for characterizing the energy exchange at the ground/water-atmosphere interface. The Satellite ClOud and Radiation Property retrieval System (SatCORPS) employs a single-channel thermal-infrared (TIR) method to retrieve Ts over clear-sky land and ocean surfaces from data taken by geostationary Earth orbit (GEO) and low Earth orbit (LEO) satellite imagers. GEO satellites can provide somewhat continuous estimates of Ts over the diurnal cycle in non-polar regions, while polar Ts retrievals from LEO imagers, such as the Advanced Very High Resolution Radiometer (AVHRR), can complement the GEO measurements. The combined global coverage of remotely sensed Ts, along with accompanying cloud and surface radiation parameters, produced in near-realtime and from historical satellite data, should be beneficial for both weather and climate applications. For example, near-realtime hourly Ts observations can be assimilated in high-temporal-resolution numerical weather prediction models and historical observations can be used for validation or assimilation of climate models. Key drawbacks to the utility of TIR-derived Ts data include the limitation to clear-sky conditions, the reliance on a particular set of analyses/reanalyses necessary for atmospheric corrections, and the dependence on viewing and illumination angles. Therefore, Ts validation with established references is essential, as is proper evaluation of Ts sensitivity to atmospheric correction source. This article presents improvements on the NASA Langley GEO satellite and AVHRR TIR-based Ts product that is derived using a single-channel technique. The resulting clear-sky skin temperature values are validated with surface references and independent satellite products. Furthermore, an empirically adjusted theoretical model of satellite land surface temperature (LST) angular anisotropy is tested to improve satellite LST retrievals. Application of the anisotropic correction yields reduced mean bias and improved precision of GOES-13 LST relative to independent Moderate-resolution Imaging Spectroradiometer (MYD11-L2) LST and Atmospheric Radiation Measurement Program ground station measurements. It also significantly reduces inter-satellite differences between LSTs retrieved simultaneously from two different imagers. The implementation of these universal corrections into the SatCORPS product can yield significant improvement in near-global-scale, near-realtime, satellite-based LST measurements. The immediate availability and broad coverage of these skin temperature observations should prove valuable to modelers and climate researchers looking for improved forecasts and better understanding of the global climate model. © Author(s) 2017."
"7201485519;24329376600;13402835300;35509639400;7004479957;35742922300;6603925960;7004468723;36010237000;57203030873;7402064802;7101959253;8866821900;6603566335;36135047900;7201504886;6603422104;7007021059;55686667100;","The Cloud Feedback Model Intercomparison Project (CFMIP) contribution to CMIP6",2017,"10.5194/gmd-10-359-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010764262&doi=10.5194%2fgmd-10-359-2017&partnerID=40&md5=13058d8755fbdbf7455ba0fce44048ba","The primary objective of CFMIP is to inform future assessments of cloud feedbacks through improved understanding of cloud-climate feedback mechanisms and better evaluation of cloud processes and cloud feedbacks in climate models. However, the CFMIP approach is also increasingly being used to understand other aspects of climate change, and so a second objective has now been introduced, to improve understanding of circulation, regional-scale precipitation, and non-linear changes. CFMIP is supporting ongoing model inter-comparison activities by coordinating a hierarchy of targeted experiments for CMIP6, along with a set of cloud-related output diagnostics. CFMIP contributes primarily to addressing the CMIP6 questions ""How does the Earth system respond to forcing?"" and ""What are the origins and consequences of systematic model biases?"" and supports the activities of the WCRP Grand Challenge on Clouds, Circulation and Climate Sensitivity. A compact set of Tier 1 experiments is proposed for CMIP6 to address this question: (1) what are the physical mechanisms underlying the range of cloud feedbacks and cloud adjustments predicted by climate models, and which models have the most credible cloud feedbacks? Additional Tier 2 experiments are proposed to address the following questions. (2) Are cloud feedbacks consistent for climate cooling and warming, and if not, why? (3) How do cloud-radiative effects impact the structure, the strength and the variability of the general atmospheric circulation in present and future climates? (4) How do responses in the climate system due to changes in solar forcing differ from changes due to CO2, and is the response sensitive to the sign of the forcing? (5) To what extent is regional climate change per CO2 doubling state-dependent (non-linear), and why? (6) Are climate feedbacks during the 20th century different to those acting on long-term climate change and climate sensitivity? (7) How do regional climate responses (e.g. in precipitation) and their uncertainties in coupled models arise from the combination of different aspects of CO2 forcing and sea surface warming? CFMIP also proposes a number of additional model outputs in the CMIP DECK, CMIP6 Historical and CMIP6 CFMIP experiments, including COSP simulator outputs and process diagnostics to address the following questions. 1. How well do clouds and other relevant variables simulated by models agree with observations? 2. What physical processes and mechanisms are important for a credible simulation of clouds, cloud feedbacks and cloud adjustments in climate models? 3. Which models have the most credible representations of processes relevant to the simulation of clouds? 4. How do clouds and their changes interact with other elements of the climate system. © Author(s) 2017."
"55976582900;","Chemistry&ndash;climate interactions of aerosol nitrate from lightning",2017,"10.5194/acp-17-1125-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010460660&doi=10.5194%2facp-17-1125-2017&partnerID=40&md5=dc18b1e3ad844cbc1838e017b8601453","Lightning represents one of the dominant emission sources for NOx in the troposphere. The direct release of oxidised nitrogen in the upper troposphere does not only affect ozone formation, but also chemical and microphysical properties of aerosol particles in this region. This study investigates the direct impact of LNOx emissions on upper-tropospheric nitrate using a global chemistry climate model. The simulation results show a substantial influence of the lightning emissions on the mixing ratios of nitrate aerosol in the upper troposphere of more than 50%. In addition to the impact on nitrate, lightning substantially affects the oxidising capacity of the atmosphere with substantial implications for gas-phase sulfate formation and new particle formation in the upper troposphere. In conjunction with the condensation of nitrates, substantial differences in the aerosol size distribution occur in the upper troposphere as a consequence of lightning. This has implications for the extinction properties of the aerosol particles and for the cloud optical properties. While the extinction is generally slightly enhanced due to the LNOx emissions, the response of the clouds is ambiguous due to compensating effects in both liquid and ice clouds. Resulting shortwave flux perturbations are of ∼-100mWm-2 as determined from several sensitivity scenarios, but an uncertainty range of almost 50% has to be defined due to the large internal variability of the system and the uncertainties in the multitude of involved processes. Despite the clear statistical significance of the influence of lightning on the nitrate concentrations, the robustness of the findings gradually decreases towards the determination of the radiative flux perturbations. © 2017 The Author(s)."
"7004881313;6603049815;8390954500;57189992234;57189992264;22633429500;6701806265;","Characterisation of boundary layer turbulent processes by the Raman lidar BASIL in the frame of HD(CP)2 Observational Prototype Experiment",2017,"10.5194/acp-17-745-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009999479&doi=10.5194%2facp-17-745-2017&partnerID=40&md5=e7e3707ac4a0dcffc3e167d2e671f6b8","Measurements carried out by the University of Basilicata Raman lidar system (BASIL) are reported to demonstrate the capability of this instrument to characterise turbulent processes within the convective boundary layer (CBL). In order to resolve the vertical profiles of turbulent variables, high-resolution water vapour and temperature measurements, with a temporal resolution of 10g s and vertical resolutions of 90 and 30 m, respectively, are considered. Measurements of higher-order moments of the turbulent fluctuations of water vapour mixing ratio and temperature are obtained based on the application of autocovariance analyses to the water vapour mixing ratio and temperature time series. The algorithms are applied to a case study (11:30-13:30 UTC, 20 April 2013) from the High Definition Clouds and Precipitation for Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE), held in western Germany in the spring 2013. A new correction scheme for the removal of the elastic signal crosstalk into the low quantum number rotational Raman signal is applied. The noise errors are small enough to derive up to fourth-order moments for both water vapour mixing ratio and temperature fluctuations. To the best of our knowledge, BASIL is the first Raman lidar with a demonstrated capability to simultaneously retrieve daytime profiles of water vapour turbulent fluctuations up to the fourth order throughout the atmospheric CBL. This is combined with the capability of measuring daytime profiles of temperature fluctuations up to the fourth order. These measurements, in combination with measurements from other lidar and in situ systems, are important for verifying and possibly improving turbulence and convection parameterisation in weather and climate models at different scales down to the grey zone (grid increment ∼ 1 km; Wulfmeyer et al., 2016). For the considered case study, which represents a well-mixed and quasi-stationary CBL, the mean boundary layer height is found to be 1290 ± 75 m above ground level (a.g.l.). Values of the integral scale for water vapour and temperature fluctuations at the top of the CBL are in the range of 70-125 and 75-225 s, respectively; these values are much larger than the temporal resolution of the measurements (10 s), which testifies that the temporal resolution considered for the measurements is sufficiently high to resolve turbulent processes down to the inertial subrange and, consequently, to resolve the major part of the turbulent fluctuations. Peak values of all moments are found in the interfacial layer in the proximity of the top of the CBL. Specifically, water vapour and temperature second-order moments (variance) have maximum values of 0.29 g2 kg-2 and 0.26 K2; water vapour and temperature third-order moments have peak values of 0.156 g3 kg-3 and-0.067 K3, while water vapour and temperature fourth-order moments have maximum values of 0.28 g4 kg-4 and 0.24 K4. Water vapour and temperature kurtosis have values of ∼ 3 in the upper portion of the CBL, which indicate normally distributed humidity and temperature fluctuations. Reported values of the higher-order moments are in good agreement with previous measurements at different locations, thus providing confidence in the possibility of using these measurements for turbulence parameterisation in weather and climate models. In the determination of the temperature profiles, particular care was dedicated to minimise potential effects associated with elastic signal crosstalk on the rotational Raman signals. For this purpose, a specific algorithm was defined and tested to identify and remove the elastic signal crosstalk and to assess the residual systematic uncertainty affecting temperature measurements after correction. The application of this approach confirms that, for the present Raman lidar system, the crosstalk factor remains constant with time; consequently an appropriate assessment of its constant value allows for a complete removal of the leaking elastic signal from the rotational Raman lidar signals at any time (with a residual error on temperature measurements after correction not exceeding 0.18 K). © 2017 The Author(s)."
"23990276200;7006256622;23082420800;57193084799;","Model evidence for low-level cloud feedback driving persistent changes in atmospheric circulation and regional hydroclimate",2017,"10.1002/2016GL071978","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010637404&doi=10.1002%2f2016GL071978&partnerID=40&md5=d480688d2d2cd56a5aaf0da2c5d8c130","Recent studies suggest that low clouds in the Pacific play an important role in the observed decadal climate variability and future climate change. In this study, we implement a novel modeling experiment designed to isolate how interactions between local and remote feedbacks associated with low cloud, SSTs, and the large-scale circulation play a significant role in the observed persistence of tropical Pacific SST and associated North American drought. The modeling approach involves the incorporation of observed patterns of satellite-derived shortwave cloud radiative effect (SWCRE) into the coupled model framework and is ideally suited for examining the role of local and large-scale coupled feedbacks and ocean heat transport in Pacific decadal variability. We show that changes in SWCRE forcing in eastern subtropical Pacific alone reproduces much of the observed changes in SST and atmospheric circulation over the past 16 years, including the observed changes in precipitation over much of the Western Hemisphere. ©2016. The Authors."
"24528897900;7402677913;7103206141;","Contrasting seasonal responses of sulfate aerosols to declining SO2 emissions in the Eastern U.S.: Implications for the efficacy of SO2 emission controls",2017,"10.1002/2016GL070695","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008331067&doi=10.1002%2f2016GL070695&partnerID=40&md5=277ca8be680a7921a4f48801e71ee532","Stringent controls have reduced U.S. SO2 emissions by over 60% since the late 1990s. These controls have been more effective at reducing surface [SO-4] in summer (June, July, and August) than in winter (December, January, and February (DJF)), a seasonal contrast that is not robustly captured by Climate Model Intercomparison Project 5 global models. We use the Geophysical Fluid Dynamics Laboratory AM3 chemistry-climate model to show that oxidant limitation during winter causes [SO-4] (DJF) to be sensitive to primary [SO-4] emissions, in-cloud titration of H2O2, and in-cloud oxidation by O3. The observed contrast in the seasonal response of [SO-4] to decreasing SO2 emissions is best explained by the O3 reaction, whose rate coefficient has increased over the past decades as a result of increasing NH3 emissions and decreasing SO2 emissions, both of which lower cloud water acidity. The fraction of SO2 oxidized to [SO-4] is projected to keep increasing in future decades, delaying improvements in wintertime air quality. ©2016. American Geophysical Union. All Rights Reserved."
"57216713239;7403564495;","Can MODIS cloud fraction fully represent the diurnal and seasonal variations at DOE ARM SGP and Manus sites?",2017,"10.1002/2016JD025954","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008402201&doi=10.1002%2f2016JD025954&partnerID=40&md5=83e7e69712300a453dd577e5902bf859","Though cloud fraction (CF) from Moderate Resolution Imaging Spectroradiometer (MODIS) has been widely used, it remains unclear whether it can fully represent the diurnal variations. This study evaluates the time representation (i.e., satellite passes’ mean value per day to represent daily average value) error in MODIS CF by using daytime-only total sky cover and continuous day-and-night radar/lidar CF (Active Remote Sensing of Clouds product, ARSCL) from 2000 to 2010 for two Atmospheric Radiation Measurement (ARM) program climate regime sites of Southern Great Plains (SGP) and Manus. By comparing the daily averaged CFs from ARSCL between using all hourly and using the MODIS-passing-time observations, it shows a correlation coefficient of 0.93 (0.88) and root mean square deviation (RMSD) of 12.68% (13.27%) over SGP (Manus) site for daily averaged CFs. Differently, it shows a better correlation coefficient of 0.97 (0.97) and smaller RMSD of 2.98% (3.97%) over SGP (Manus) site for monthly averaged CFs. These suggest that considerable errors could be introduced while using the MODIS CF observed at several fixed time points a day to represent average CF at different time scales. Monthly time representation errors have also been evaluated for daytime only and nighttime only, which show even larger values. A further analysis shows that uncertainties caused by the time representation account for about 23% (21%) of the total differences between surface and MODIS CFs over SGP (Manus) site at monthly time scale. © 2016. American Geophysical Union. All Rights Reserved."
"56565518500;6603584184;57192717960;56697819500;8661520500;","A critical evaluation of modeled solar irradiance over California for hydrologic and land surface modeling",2017,"10.1002/2016JD025527","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007583932&doi=10.1002%2f2016JD025527&partnerID=40&md5=0f33b52f8e487f110092e6467163e63b","Studies of land surface processes in complex terrain often require estimates of meteorological variables, i.e., the incoming solar irradiance (Qsi), to force land surface models. However, estimates of Qsi are rarely evaluated within mountainous environments. We evaluated four methods of estimating Qsi: the CERES Synoptic Radiative Fluxes and Clouds (SYN) product, MTCLIM, a regional reanalysis product derived from a long-term Weather Research and Forecast simulation, and Mountain Microclimate Simulation Model (MTCLIM). These products are evaluated over the Central Valley and Sierra Nevada mountains in California, a region with meteorology strongly impacted by complex topography. We used a spatially dense network of Qsi observations (n = 70) to characterize the spatial characteristics of Qsi uncertainty. Observation sites were grouped into five subregions, and Qsi estimates were evaluated against observations in each subregion. Large monthly biases (up to 80Wm-2) outside the observational uncertainty were found for all estimates in all subregions examined, typically reaching a maximum in the spring. We found that MTCLIM and SYN generally perform the best across all subregions. Differences between Qsi estimates were largest over the Sierra Nevada, with seasonal differences exceeding 50Wm-2. Disagreements in Qsi were especially pronounced when averaging over high-elevation basins, with monthly differences up to 80Wm-2. Biases in estimated Qsi predominantly occurred with darker than normal conditions associated with precipitation (a proxy for cloud cover), while the presence of aerosols and water vapor was unable to explain the biases. Users of Qsi estimates in regions of complex topography, especially those estimating Qsi to force land surface models, need to be aware of this source of uncertainty. © 2016. American Geophysical Union. All Rights Reserved."
"56424780700;55916575700;8287822500;","Working fluid selection and electrical performance optimisation of a domestic solar-ORC combined heat and power system for year-round operation in the UK",2017,"10.1016/j.apenergy.2016.04.041","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975108648&doi=10.1016%2fj.apenergy.2016.04.041&partnerID=40&md5=21d14448b939584ca25bf562529c6fc6","In this paper, we examine the electrical power-generation potential of a domestic-scale solar combined heating and power (S-CHP) system featuring an organic Rankine cycle (ORC) engine and a 15-m2 non-concentrated solar-thermal collector array. The system is simulated with a range of organic working fluids and its performance is optimised for operation in the UK climate. The findings are applicable to similar geographical locations with significant cloud coverage, a low solar resource and limited installation areas. A key feature of the system's design is the implementation of fixed fluid flow-rates during operation in order to avoid penalties in the performance of components suffered at part-load. Steady operation under varying solar irradiance conditions is provided by way of a working-fluid buffer vessel at the evaporator outlet, which is maintained at the evaporation temperature and pressure of the ORC. By incorporating a two-stage solar collector/evaporator configuration, a maximum net annual electrical work output of 1070 kW h yr−1 (continuous average power of 122 W) and a solar-to-electrical efficiency of 6.3% is reported with HFC-245ca as the working fluid at an optimal evaporation saturation temperature of 126 °C (corresponding to an evaporation pressure of 16.2 bar). This is equivalent to ∼32% of the electricity demand of a typical/average UK home, and represents an improvement of more than 50% over a recent effort by the same authors based on an earlier S-CHP system configuration and HFC-245fa as the working fluid [1], thus highlighting the gains possible when using optimal system configurations and fluids and suggesting that significant further improvements may be possible. A performance and simple cost comparison with stand-alone, side-by-side PV and solar-thermal heating systems is presented. © 2016 The Authors"
"37051480000;56418561200;23978405300;6506718302;56262351900;6507755223;","UCLALES-SALSA v1.0: A large-eddy model with interactive sectional microphysics for aerosol, clouds and precipitation",2017,"10.5194/gmd-10-169-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009437837&doi=10.5194%2fgmd-10-169-2017&partnerID=40&md5=8a85707d0214d8bb2ac63eefae36de2c","Challenges in understanding the aerosol-cloud interactions and their impacts on global climate highlight the need for improved knowledge of the underlying physical processes and feedbacks as well as their interactions with cloud and boundary layer dynamics. To pursue this goal, increasingly sophisticated cloud-scale models are needed to complement the limited supply of observations of the interactions between aerosols and clouds. For this purpose, a new large-eddy simulation (LES) model, coupled with an interactive sectional description for aerosols and clouds, is introduced. The new model builds and extends upon the well-characterized UCLA Large-Eddy Simulation Code (UCLALES) and the Sectional Aerosol module for Large-Scale Applications (SALSA), hereafter denoted as UCLALES-SALSA. Novel strategies for the aerosol, cloud and precipitation bin discretisation are presented. These enable tracking the effects of cloud processing and wet scavenging on the aerosol size distribution as accurately as possible, while keeping the computational cost of the model as low as possible. The model is tested with two different simulation set-ups: a marine stratocumulus case in the DYCOMS-II campaign and another case focusing on the formation and evolution of a nocturnal radiation fog. It is shown that, in both cases, the size-resolved interactions between aerosols and clouds have a critical influence on the dynamics of the boundary layer. The results demonstrate the importance of accurately representing the wet scavenging of aerosol in the model. Specifically, in a case with marine stratocumulus, precipitation and the subsequent removal of cloud activating particles lead to thinning of the cloud deck and the formation of a decoupled boundary layer structure. In radiation fog, the growth and sedimentation of droplets strongly affect their radiative properties, which in turn drive new droplet formation. The size-resolved diagnostics provided by the model enable investigations of these issues with high detail. It is also shown that the results remain consistent with UCLALES (without SALSA) in cases where the dominating physical processes remain well represented by both models. © Author(s) 2017."
"57210222492;56119272900;56681868600;28568039300;7103101609;7003440089;","Atmospheric moisture supersaturation in the near-surface atmosphere at Dome C, Antarctic Plateau",2017,"10.5194/acp-17-691-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009348342&doi=10.5194%2facp-17-691-2017&partnerID=40&md5=fe912ad5a71279735b023c108b80b691","Supersaturation often occurs at the top of the troposphere where cirrus clouds form, but is comparatively unusual near the surface where the air is generally warmer and laden with liquid and/or ice condensation nuclei. One exception is the surface of the high Antarctic Plateau. One year of atmospheric moisture measurement at the surface of Dome C on the East Antarctic Plateau is presented. The measurements are obtained using commercial hygrometry sensors modified to allow air sampling without affecting the moisture content, even in the case of supersaturation. Supersaturation is found to be very frequent. Common unadapted hygrometry sensors generally fail to report supersaturation, and most reports of atmospheric moisture on the Antarctic Plateau are thus likely biased low. The measurements are compared with results from two models implementing cold microphysics parameterizations: the European Center for Medium-range Weather Forecasts through its operational analyses, and the Model Atmosphérique Régional. As in the observations, supersaturation is frequent in the models but the statistical distribution differs both between models and observations and between the two models, leaving much room for model improvement. This is unlikely to strongly affect estimations of surface sublimation because supersaturation is more frequent as temperature is lower, and moisture quantities and thus water fluxes are small anyway. Ignoring supersaturation may be a more serious issue when considering water isotopes, a tracer of phase change and temperature, largely used to reconstruct past climates and environments from ice cores. Because observations are easier in the surface atmosphere, longer and more continuous in situ observation series of atmospheric supersaturation can be obtained than higher in the atmosphere to test parameterizations of cold microphysics, such as those used in the formation of high-altitude cirrus clouds in meteorological and climate models. © Author(s) 2017."
"56940125000;7004299063;55207713000;56418532300;35096299800;","The G4Foam Experiment: Global climate impacts of regional ocean albedo modification",2017,"10.5194/acp-17-595-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009454856&doi=10.5194%2facp-17-595-2017&partnerID=40&md5=ecdd63596a4bc8065813e853a2906b48","Reducing insolation has been proposed as a geoengineering response to global warming. Here we present the results of climate model simulations of a unique Geoengineering Model Intercomparison Project Testbed experiment to investigate the benefits and risks of a scheme that would brighten certain oceanic regions. The National Center for Atmospheric Research CESM CAM4-Chem global climate model was modified to simulate a scheme in which the albedo of the ocean surface is increased over the subtropical ocean gyres in the Southern Hemisphere. In theory, this could be accomplished using a stable, nondispersive foam, comprised of tiny, highly reflective microbubbles. Such a foam has been developed under idealized conditions, although deployment at a large scale is presently infeasible. We conducted three ensemble members of a simulation (G4Foam) from 2020 through to 2069 in which the albedo of the ocean surface is set to 0.15 (an increase of 150 %) over the three subtropical ocean gyres in the Southern Hemisphere, against a background of the RCP6.0 (representative concentration pathway resulting in +6 W mg-2 radiative forcing by 2100) scenario. After 2069, geoengineering is ceased, and the simulation is run for an additional 20 years. Global mean surface temperature in G4Foam is 0.6 K lower than RCP6.0, with statistically significant cooling relative to RCP6.0 south of 30° N. There is an increase in rainfall over land, most pronouncedly in the tropics during the June-July-August season, relative to both G4SSA (specified stratospheric aerosols) and RCP6.0. Heavily populated and highly cultivated regions throughout the tropics, including the Sahel, southern Asia, the Maritime Continent, Central America, and much of the Amazon experience a statistically significant increase in precipitation minus evaporation. The temperature response to the relatively modest global average forcing of g-1.5 W mg-2 is amplified through a series of positive cloud feedbacks, in which more shortwave radiation is reflected. The precipitation response is primarily the result of the intensification of the southern Hadley cell, as its mean position migrates northward and away from the Equator in response to the asymmetric cooling. © 2017 Author(s)."
"57192915106;55938109300;57148462400;7004607037;12544502800;39361670300;","Evaluating the representation of aerosol optical properties using an online coupled model over the Iberian Peninsula",2017,"10.5194/acp-17-277-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009115328&doi=10.5194%2facp-17-277-2017&partnerID=40&md5=e2bd61eee240a627694bd6e48ccaaab4","The effects of atmospheric aerosol particles on the Earth's climate mainly depend on their optical, microphysical and chemical properties, which modify the Earth's radiative budget. The aerosol radiative effects can be divided into direct and semi-direct effects, produced by the aerosol-radiation interactions (ARIs), and indirect effects, produced by aerosol-cloud interactions (ACIs). In this sense the objective of this work is to assess whether the inclusion of aerosol radiative feedbacks in the online coupled WRFChem model improves the modelling outputs over the Iberian Peninsula (IP) and surrounding water areas. For this purpose, the methodology is based on the evaluation of modelled aerosol optical properties under different simulation scenarios. The evaluated data come from two WRF-Chem simulations for the IP differing in the inclusion/no-inclusion of ARIs and ACIs (RF/NRF simulations). The case studies cover two episodes with different aerosol types over the IP in 2010, namely a Saharan dust outbreak and a forest fire episode. The evaluation uses observational data from AERONET (Aerosol Robotic Network) stations and MODIS (Moderate Resolution Imaging Spectroradiometer) sensor, including aerosol optical depth (AOD) and Ångström exponent (AE). Experimental data of aerosol vertical distribution from the EARLINET (European Aerosol Research Lidar Network) Granada station are used for checking the models. The results indicate that for the spatial distribution the bestrepresented variable is AOD and the largest improvements when including the aerosol radiative feedbacks are found for the vertical distribution. In the case of the dust outbreak, a slight improvement (worsening) is produced over the areas with medium (high/low) levels of AOD(-9%=C12% of improvement) when including the aerosol radiative feedbacks. For the wildfire episode, improvements of AOD representation (up to 11 %) over areas further away from emission sources are estimated, which compensates for the computational effort of including aerosol feedbacks in the simulations. No clear improvement is observed for the AE representation, the variability of which is largely underpredicted by both simulations. © Author(s) 2017."
"55245030000;7102604282;","Why do general circulation models overestimate the aerosol cloud lifetime effect? A case study comparing CAM5 and a CRM",2017,"10.5194/acp-17-21-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008936666&doi=10.5194%2facp-17-21-2017&partnerID=40&md5=a2a495505bc1bc8e1dd0aaf013fcb864","Observation-based studies have shown that the aerosol cloud lifetime effect or the increase of cloud liquid water path (LWP) with increased aerosol loading may have been overestimated in climate models. Here, we simulate shallow warm clouds on 27 May 2011 at the southern Great Plains (SGP) measurement site established by the Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program using a single-column version of a global climate model (Community Atmosphere Model or CAM) and a cloud resolving model (CRM). The LWP simulated by CAM increases substantially with aerosol loading while that in the CRM does not. The increase of LWP in CAM is caused by a large decrease of the autoconversion rate when cloud droplet number increases. In the CRM, the autoconversion rate is also reduced, but this is offset or even outweighed by the increased evaporation of cloud droplets near the cloud top, resulting in an overall decrease in LWP. Our results suggest that climate models need to include the dependence of cloud top growth and the evaporation/condensation process on cloud droplet number concentrations. © 2017 The Author(s)."
"57193803894;7004325649;6506827279;7006783796;","Quantifying the dependence of satellite cloud retrievals on instrument uncertainty",2017,"10.1175/JCLI-D-16-0429.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027247940&doi=10.1175%2fJCLI-D-16-0429.1&partnerID=40&md5=3c90cfe69d4cb3f2e1fdaeada95c190c","Cloud response to Earth's changing climate is one of the largest sources of uncertainty among global climate model (GCM) projections. Two of the largest sources of uncertainty are the spread in equilibrium climate sensitivity (ECS) and uncertainty in radiative forcing due to uncertainty in the aerosol indirect effect. Satellite instruments with sufficient accuracy and on-orbit stability to detect climate change-scale trends in cloud properties will improve confidence in the understanding of the relationship between observed climate change and cloud property trends, thus providing information to better constrain ECS and radiative forcing. This study applies a climate change uncertainty framework to quantify the impact of measurement uncertainty on trend detection times for cloud fraction, effective temperature, optical thickness, and water cloud effective radius. Although GCMs generally agree that the total cloud feedback is positive, disagreement remains on its magnitude. With the climate uncertainty framework, it is demonstrated how stringent measurement uncertainty requirements for reflected solar and infrared satellite measurements enable improved constraint of SW and LW cloud feedbacks and the ECS by significantly reducing trend uncertainties for cloud fraction, optical thickness, and effective temperature. The authors also demonstrate improved constraint on uncertainty in the aerosol indirect effect by reducing water cloud effective radius trend uncertainty. © 2017 American Meteorological Society."
"30667558200;13403622000;","Improving climate projections by understanding how cloud phase affects radiation",2017,"10.1002/2017JD026927","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018414003&doi=10.1002%2f2017JD026927&partnerID=40&md5=1742d66001dffeb6760b4ff2d91be3b2","Whether a cloud is predominantly water or ice strongly influences interactions between clouds and radiation coming down from the Sun or up from the Earth. Being able to simulate cloud phase transitions accurately in climate models based on observational data sets is critical in order to improve confidence in climate projections, because this uncertainty contributes greatly to the overall uncertainty associated with cloud-climate feedbacks. Ultimately, it translates into uncertainties in Earth’s sensitivity to higher CO2 levels. While a lot of effort has recently been made toward constraining cloud phase in climate models, more remains to be done to document the radiative properties of clouds according to their phase. Here we discuss the added value of a new satellite data set that advances the field by providing estimates of the cloud radiative effect as a function of cloud phase and the implications for climate projections. © 2017. American Geophysical Union."
"13405658600;","Cosmic rays, aerosols, clouds, and climate: Recent findings from the CLOUD experiment",2017,"10.1002/2017JD027475","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028084095&doi=10.1002%2f2017JD027475&partnerID=40&md5=c16b4d325c8caff8918bb072ac942860","The Cosmics Leaving OUtdoor Droplets (CLOUD) experiment was created to systematically test the link between galactic cosmic rays (GCR) and climate, specifically, the connection of ions from GCR to aerosol nucleation and cloud condensation nuclei (CCN), the particles on which cloud droplets form. The CLOUD experiment subsequently unlocked many of the mysteries of nucleation and growth in our atmosphere, and it has improved our understanding of human influences on climate. Their most recent publication (Gordon et al., 2017) provides their first estimate of the GCR-CCN connection, and they show that CCN respond too weakly to changes in GCR to yield a significant influence on clouds and climate. © 2017. American Geophysical Union. All Rights Reserved."
"55940397300;7005219614;55976582900;55965624000;15019752400;55460555300;","Aerosol physicochemical effects on CCN activation simulated with the chemistry-climate model EMAC",2017,"10.1016/j.atmosenv.2017.03.036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019623206&doi=10.1016%2fj.atmosenv.2017.03.036&partnerID=40&md5=468ab4841c9648af230db6e9a4505d3c","This study uses the EMAC atmospheric chemistry-climate model to simulate cloud properties with a prognostic cloud droplet nucleation scheme. We present modeled global distributions of cloud condensation nuclei (CCN) number concentrations and CCN activation rates, together with the effective hygroscopicity parameter κ, to describe the aerosol chemical composition effect on CCN activation. Large particles can easily activate into cloud droplets, even at low κ values due to the dominant size effect in cloud droplet formation. Small particles are less efficiently activated as CCN, and are more sensitive to aerosol composition and supersaturation. Since the dominant fraction of small particles generally originates from anthropogenic precursor emissions over land, this study focuses on the influence of the continental atmosphere, using a prognostic cloud droplet nucleation scheme that considers aerosol-cloud interactions during cloud formation, together with a double-moment cloud microphysics scheme. The agreement of simulated clouds and climate with observations generally improves over the Northern Hemisphere continents, particularly high air pollution regions such as Eastern US, Europe, East Asia by accounting for aerosol-cloud interactions that include impacts of chemical composition on CCN activation. © 2017 The Authors"
"56203249800;7006550762;6507308842;57193132723;9242540400;55408944000;","Interactive nature of climate change and aerosol forcing",2017,"10.1002/2016JD025809","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017335882&doi=10.1002%2f2016JD025809&partnerID=40&md5=b9230d19d8ff7f74a312b4fdabf47689","The effect of changing cloud cover on climate, based on cloud-aerosol interactions, is one of the major unknowns for climate forcing and climate sensitivity. It has two components: (1) the impact of aerosols on clouds and climate due to in situ interactions (i.e., rapid response) and (2) the effect of aerosols on the cloud feedback that arises as climate changes-climate feedback response. We examine both effects utilizing the NASA Goddard Institute for Space Studies ModelE2 to assess the indirect effect, with both mass-based and microphysical aerosol schemes, in transient twentieth century simulations. We separate the rapid response and climate feedback effects by making simulations with a coupled version of the model as well as one with no sea surface temperature or sea ice response (“atmosphere-only” simulations). We show that the indirect effect of aerosols on temperature is altered by the climate feedbacks following the ocean response, and this change differs depending upon which aerosol model is employed. Overall, the effective radiative forcing (ERF) for the “direct effect” of aerosol-radiation interaction (ERFari) ranges between 0.2 and 0.6Wm-2 for atmosphere-only experiments, while the total effective radiative forcing, including the indirect effect (ERFari+aci) varies between about -0.4 and 1.1Wm-2for atmosphere-only simulations; both ranges are in agreement with those given in Intergovernmental Panel on Climate Change (2013). Including the full feedback of the climate system lowers these ranges to -0.2 to 0.5Wm-2 for ERFari and -0.3 to 0.74Wm-2 for ERFari+aci. With both aerosol schemes, the climate change feedbacks have reduced the global average indirect radiative effect of atmospheric aerosols relative to what the emission changes would have produced, at least partially due to its effect on tropical upper tropospheric clouds. © 2017. American Geophysical Union. All Rights Reserved."
"57193321831;6603925960;57207507108;57196262639;57203030873;6507594716;30667558200;7202016984;7003865921;","Direct atmosphere opacity observations from CALIPSO provide new constraints on cloud-radiation interactions",2017,"10.1002/2016JD025946","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013005007&doi=10.1002%2f2016JD025946&partnerID=40&md5=d57f64aa4f210fccbf9698896bbf72db","The spaceborne lidar CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) directly measures atmospheric opacity. In 8 years of CALIPSO observations, we find that 69% of vertical profiles penetrate through the complete atmosphere. The remaining 31% do not reach the surface, due to opaque clouds. The global mean altitude of full attenuation of the lidar beam (z_opaque) is 3.2 km, but there are large regional variations in this altitude. Of relevance to cloud-climate studies, the annual zonal mean longwave cloud radiative effect and annual zonal mean z_opaque weighted by opaque cloud cover are highly correlated (0.94). The annual zonal mean shortwave cloud radiative effect and annual zonal mean opaque cloud cover are also correlated (_0.95). The new diagnostics introduced here are implemented within a simulator framework to enable scale-aware and definition-aware evaluation of the LMDZ5B global climate model. The evaluation shows that the model overestimates opaque cloud cover (31% obs. versus 38% model) and z_opaque (3.2 km obs. versus 5.1 km model). In contrast, the model underestimates thin cloud cover (35% obs. versus 14% model). Further assessment shows that reasonable agreement between modeled and observed longwave cloud radiative effects results from compensating errors between insufficient warming by thin clouds and excessive warming due to overestimating both z_opaque and opaque cloud cover. This work shows the power of spaceborne lidar observations to directly constrain cloud-radiation interactions in both observations and models. © 2017. American Geophysical Union. All Rights Reserved."
"57203053317;","Why does knowledge of past aerosol forcingmatter for future climate change?",2017,"10.1002/2017JD026962","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018913306&doi=10.1002%2f2017JD026962&partnerID=40&md5=424e874ba4037b96467ff15fe0e6a076","Aerosol particles scatter and absorb radiation and interact with cloud particles. The net aerosol forcing since preindustrial times is negative and has offset part of the greenhouse gas warming. It dominates the uncertainty of the overall anthropogenic forcing. This large uncertainty results from gaps in our knowledge on the underlying aerosol and cloud microphysical processes and aerosol-cloud interactions as well as their representation in global coupled aerosol-climate models. A recent paper by Nazarenko et al. (2017) illustrates how the anthropogenic aerosol forcing, especially the effective radiative forcing that includes aerosol-cloud and aerosol-radiation interactions, depends on climate feedbacks and on the employed aerosol model. © 2017. American Geophysical Union. All Rights Reserved."
"25647334300;7103158465;23065650200;25031430500;56463153400;","Improvements in global climate model microphysics using a consistent representation of ice particle properties",2017,"10.1175/JCLI-D-16-0050.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008603829&doi=10.1175%2fJCLI-D-16-0050.1&partnerID=40&md5=8af6be4e8883863d138bfb4988debdaf","This paper describes a new approach for representing ice microphysics in climate models. In contrast with most previous schemes, this approach does not include separate categories for cloud and precipitating ice and instead uses a single two-moment category to represent all solid hydrometeors. Thus, there is no need for an ice ""autoconversion"" size threshold parameter, which has a critical impact on simulated climate in the Community Atmosphere Model (CAM5) yet is poorly constrained by theory or observations. Further, in the new treatment, all ice microphysical processes and parameters, including ice effective radius and mean fall speed, are formulated self-consistently and flexibly based on empirical ice particle mass-size and projected area-size relationships. This means that the scheme can represent the physical coupling between bulk particle density, mean fall speed, and effective radius, which is not possible in current schemes. Two different methods for specifying these relationships based on observations are proposed. The new scheme is tested in global simulations using CAM5. Differences in simulations using the two methods for specifying the mass- and projected area-size relationships, particularly the cloud radiative forcing, are attributable mainly to the effects on mean ice particle fall speed, impacting sedimentation and ice water path. With some tuning of parameters involved in calculating homogeneous freezing it produces a similar climate compared to the simulations using the original CAM5 microphysics. Thus, it can produce a comparable climate while improving the physical basis and self-consistency of ice particle properties and parameters. © 2017 American Meteorological Society."
"7005528388;7102171439;6603126554;15726427000;7201607592;7401793588;","On the response of MODIS cloud coverage to global mean surface air temperature",2017,"10.1002/2016JD025174","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013004918&doi=10.1002%2f2016JD025174&partnerID=40&md5=300c27d9e86336c6cd58309db9fbbf75","The global surface temperature change (ΔTs) mediated cloud cover response is directly related to cloud-climate feedback. Using satellite remote sensing data to relate cloud and climate requires a well-calibrated, stable,and consistent long-term cloud data record. The Collection 5.1 (C5) Moderate Resolution Imaging Spectroradiometer (MODIS) cloud observations have been widely used for this purpose. However, the MODIS data quality varies greatly with the surface type, spectral region, cloud type, and time periods of study, which calls for additional caution when applying such data to studies on cloud cover temporal trends and variability. Using 15 years of cloud observations made by Terra and Aqua MODIS, we analyze the ΔTs-mediated cloud cover response for different cloud types by linearly regressing the monthly anomaly of cloud cover (ΔC) with the monthly anomaly of global Ts. The Collection 6 (C6) Aqua data exhibit a similar cloud response to the long-term counterpart simulated by advanced climate models. A robust increase in altitude with increasingΔTsis found for high clouds, while a robust decrease of ΔC is noticed for optically thick low clouds. The large differences betweenC5 andC6results are from improvements in calibration and cloud retrieval algorithms. The large positive cloud cover responses with data after2010andthe strong sensitivity to time period obtained from the Terra (C5 and C6) data are likely due to calibration drift that has not been corrected, suggesting that the previous estimate of the short-term cloud cover response from the these data should be revisited. © 2016. American Geophysical Union. All Rights Reserved."
"6603658865;35319628300;56015168300;36947127700;56015123900;56015409500;36059727800;47161686100;","MERRA Analytic Services: Meeting the Big Data challenges of climate science through cloud-enabled Climate Analytics-as-a-Service",2017,"10.1016/j.compenvurbsys.2013.12.003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84892956198&doi=10.1016%2fj.compenvurbsys.2013.12.003&partnerID=40&md5=8e2dee5146e44768efeab04a4bd63a53","Climate science is a Big Data domain that is experiencing unprecedented growth. In our efforts to address the Big Data challenges of climate science, we are moving toward a notion of Climate Analytics-as-a-Service (CAaaS). We focus on analytics, because it is the knowledge gained from our interactions with Big Data that ultimately produce societal benefits. We focus on CAaaS because we believe it provides a useful way of thinking about the problem: a specialization of the concept of business process-as-a-service, which is an evolving extension of IaaS, PaaS, and SaaS enabled by Cloud Computing. Within this framework, Cloud Computing plays an important role; however, we see it as only one element in a constellation of capabilities that are essential to delivering climate analytics as a service. These elements are essential because in the aggregate they lead to generativity, a capacity for self-assembly that we feel is the key to solving many of the Big Data challenges in this domain. MERRA Analytic Services (MERRA/AS) is an example of cloud-enabled CAaaS built on this principle. MERRA/AS enables MapReduce analytics over NASA's Modern-Era Retrospective Analysis for Research and Applications (MERRA) data collection. The MERRA reanalysis integrates observational data with numerical models to produce a global temporally and spatially consistent synthesis of 26 key climate variables. It represents a type of data product that is of growing importance to scientists doing climate change research and a wide range of decision support applications. MERRA/AS brings together the following generative elements in a full, end-to-end demonstration of CAaaS capabilities: (1) high-performance, data proximal analytics, (2) scalable data management, (3) software appliance virtualization, (4) adaptive analytics, and (5) a domain-harmonized API. The effectiveness of MERRA/AS has been demonstrated in several applications. In our experience, Cloud Computing lowers the barriers and risk to organizational change, fosters innovation and experimentation, facilitates technology transfer, and provides the agility required to meet our customers’ increasing and changing needs. Cloud Computing is providing a new tier in the data services stack that helps connect earthbound, enterprise-level data and computational resources to new customers and new mobility-driven applications and modes of work. For climate science, Cloud Computing's capacity to engage communities in the construction of new capabilities is perhaps the most important link between Cloud Computing and Big Data. © 2014"
"15050523700;15047538100;26436096300;55667257200;","Role of interactions between cloud microphysics, dynamics and aerosol in the heavy rainfall event of June 2013 over Uttarakhand, India",2017,"10.1002/qj.2983","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013356503&doi=10.1002%2fqj.2983&partnerID=40&md5=e3012ae528e333560cb3f0a1f7539096","In this study, we propose a hypothesis, supported by numerical model simulations, concerning the role of cloud microphysical processes and aerosols in the invigoration of an extreme rainfall event over Uttarakhand in June 2013. The interactions among dynamics, thermodynamics and microphysical processes and their feedbacks play a vital role in the occurrence of extreme events. To test the proposed hypothesis, Weather Research and Forecasting (WRF) simulations are carried out with three different microphysical schemes (i.e. WDM6, Morrison, and CLR). The role of aerosol indirect effects in the process of invigoration of precipitation is demonstrated with a high-resolution regional model for the extreme event over the foothills of the Himalayas. The extreme event is characterized by the strong north–south tropospheric temperature gradient and strong moisture convergence. Forced uplift beyond the freezing level initiates a precipitation process which involves cloud ice and mixed-phase cloud microphysics and latent heat release; further, it invigorates convection and enhances precipitation. Results pinpoint that the role of microphysical processes are very crucial during such a type of extreme event. Additionally, the result accentuates the importance of aerosols on the deep convective cloud systems which have influence through invigoration and involvement of complex interactions between aerosol, large-scale dynamics and cloud microphysics. © 2016 Royal Meteorological Society"
"57193443516;6602999057;56522444900;6506286986;57193439898;","Why do global climate models struggle to represent low-level clouds in the west african summer monsoon?",2017,"10.1175/JCLI-D-16-0451.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014031315&doi=10.1175%2fJCLI-D-16-0451.1&partnerID=40&md5=3edfb50284f4cc228d9ca04b0c31ffda","Climate models struggle to realistically represent the West African monsoon (WAM), which hinders reliable future projections and the development of adequate adaption measures. Low-level clouds over southern West Africa (58-108N, 88W-88E) during July-September are an integral part of the WAM through their effect on the surface energy balance and precipitation, but their representation in climate models has received little attention. Here 30 (20) years of output from 18 (8) models participating in phase 5 of the Coupled Model Intercomparison Project (Year of Tropical Convection) are used to identify cloud biases and their causes. Compared to ERA-Interim reanalyses, many models show large biases in low-level cloudiness of both signs and a tendency to too high elevation and too weak diurnal cycles. At the same time, these models tend to have too strong low-level jets, the impact of which is unclear because of concomitant effects on temperature and moisture advection as well as turbulent mixing. Part of the differences between the models and ERA-Interim appear to be related to the different subgrid cloud schemes used. While nighttime tendencies in temperature and humidity are broadly realistic in most models, daytime tendencies show large problems with the vertical transport of heat and moisture. Many models simulate too low near-surface relative humidities, leading to insufficient low cloud cover and abundant solar radiation, and thus a too large diurnal cycle in temperature and relative humidity. In the future, targeted model sensitivity experiments will be needed to test possible feedback mechanisms between low clouds, radiation, boundary layer dynamics, precipitation, and the WAM circulation. © 2017 American Meteorological Society."
"7004993886;7005634455;","Simulation of late summer arctic clouds during ASCOS with polar WRF",2017,"10.1175/MWR-D-16-0079.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011708600&doi=10.1175%2fMWR-D-16-0079.1&partnerID=40&md5=39bcbb5e697dc327a63a6b673a1156a0","Low-level clouds are extensive in the Arctic and contribute to inadequately understood feedbacks within the changing regional climate. The simulation of low-level clouds, including mixed-phase clouds, over the Arctic Ocean during summer and autumn remains a challenge for both real-time weather forecasts and climate models. Here, improved cloud representations are sought with high-resolution mesoscale simulations of the August-September 2008 Arctic Summer Cloud Ocean Study (ASCOS) with the latest polar-optimized version (3.7.1) of the Weather Research and Forecasting (Polar WRF) Model with the advanced two-moment Morrison microphysics scheme. Simulations across several synoptic regimes for 10 August-3 September 2008 are performed with three domains including an outer domain at 27-km grid spacing and nested domains at 9- and 3-km spacing. These are realistic horizontal grid spacings for common mesoscale applications. The control simulation produces excessive cloud liquid water in low clouds resulting in a large deficit in modeled incident shortwave radiation at the surface. Incident longwave radiation is less sensitive. A change in the sea ice albedo toward the larger observed values during ASCOS resulted in somewhat more realistic simulations. More importantly, sensitivity tests show that a reduction in specified liquid cloud droplet number to very pristine conditions increases liquid precipitation, greatly reduces the excess in simulated low-level cloud liquid water, and improves the simulated incident shortwave and longwave radiation at the surface. © 2017 American Meteorological Society."
"25924878400;57193132723;7404829395;56003457200;","An improved convective ice parameterization for the NASA GISS global climate model and impacts on cloud ice simulation",2017,"10.1175/JCLI-D-16-0346.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008226088&doi=10.1175%2fJCLI-D-16-0346.1&partnerID=40&md5=3cac6d168b629b23fe4e9366d087d3f4","Partitioning of convective ice into precipitating and detrained condensate presents a challenge for GCMs since partitioning depends on the strength and microphysics of the convective updraft. It is an important issue because detrainment of ice from updrafts influences the development of stratiform anvils, impacts radiation, and can affect GCM climate sensitivity. Recent studies have shown that the CMIP5 configurations of the Goddard Institute for Space Studies (GISS) GCM simulated upper-tropospheric ice water content (IWC) that exceeded an estimated upper bound by a factor of 2. Partly in response to this bias, a new GCM parameterization of convective cloud ice has been developed that incorporates new ice particle fall speeds and convective outflow particle size distributions (PSDs) from the NASA African Monsoon Multidisciplinary Analyses (NAMMA), NASA Tropical Composition, Cloud and Climate Coupling (TC4), DOE ARM-NASA Midlatitude Continental Convective Clouds Experiment (MC3E), and DOE ARM Small Particles in Cirrus (SPARTICUS) field campaigns. The new parameterization assumes a normalized gamma PSD with two novel developments: no explicit assumption for particle habit in the calculation of mass distributions, and a formulation for translating ice particle fall speeds as a function of maximum diameter into fall speeds as a function of melted-equivalent diameter. Two parameters (particle volume- and projected area-weighted equivalent diameter) are diagnosed as a function of temperature and IWC in the convective plume, and these parameters constrain the shape and scale of the normalized gamma PSD. The diagnosed fall speeds and PSDs are combined with the GCM's parameterized convective updraft vertical velocity to partition convective updraft condensate into precipitating and detrained components. A 5-yr prescribed sea surface temperature GCM simulation shows a 30%-50% decrease in upper-tropospheric deep convective IWC, bringing the tropical and global mean ice water path into closer agreement with CloudSat best estimates. © 2017 American Meteorological Society."
"55338676800;7101959253;57206503877;35494005000;7202652226;","Assessing the accuracy of MISR and MISR-simulated cloud top heights using CloudSat- and CALIPSO-retrieved hydrometeor profiles",2017,"10.1002/2016JD025510","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014695061&doi=10.1002%2f2016JD025510&partnerID=40&md5=a7264f5895e461ca90a35e8827ae895d","Satellite retrievals of cloud properties are often used in the evaluation of global climate models, and in recent years satellite instrument simulators have been used to account for known retrieval biases in order to make more consistent comparisons between models and retrievals. Many of these simulators have seen little critical evaluation. Here we evaluate the Multiangle Imaging Spectroradiometer (MISR) simulator by using visible extinction profiles retrieved from a combination of CloudSat, CALIPSO, MODIS, and AMSR-E observations as inputs to the MISR simulator and comparing cloud top height statistics from the MISR simulator with those retrieved by MISR. Overall, we find that the occurrence of middle- and high-altitude topped clouds agrees well between MISR retrievals and the MISR-simulated output, with distributions of middle- and high-topped cloud cover typically agreeing to better than 5% in both zonal and regional averages. However, there are significant differences in the occurrence of low-topped clouds between MISR retrievals and MISR-simulated output that are due to differences in the detection of low-level clouds between MISR and the combined retrievals used to drive the MISR simulator, rather than due to errors in the MISR simulator cloud top height adjustment. This difference highlights the importance of sensor resolution and boundary layer cloud spatial structure in determining low-altitude cloud cover. The MISR-simulated and MISR-retrieved cloud optical depth also show systematic differences, which are also likely due in part to cloud spatial structure. © 2017. American Geophysical Union. All Rights Reserved."
"8856938500;55581504800;57194659730;55838951000;23090602200;57188731710;56487354500;","Sensitivity of simulated summer monsoonal precipitation in Langtang Valley, Himalaya, to cloud microphysics schemes in WRF",2017,"10.1002/2016JD025801","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021454264&doi=10.1002%2f2016JD025801&partnerID=40&md5=810b9b2547b5593eb6527d1dcb2536b2","A better understanding of regional-scale precipitation patterns in the Himalayan region is required to increase our knowledge of the impacts of climate change on downstream water availability. This study examines the impact of four cloud microphysical schemes (Thompson, Morrison, Weather Research and Forecasting (WRF) single-moment 5-class, and WRF double-moment 6-class) on summer monsoon precipitation in the Langtang Valley in the central Nepalese Himalayas, as simulated by the WRF model at 1 km grid spacing for a 10 day period in July 2012. The model results are evaluated through a comparison with surface precipitation and radiation measurements made at two observation sites. Additional understanding is gained from a detailed examination of the microphysical characteristics simulated by each scheme, which are compared with measurements using a spaceborne radar/lidar cloud product. Also examined are the roles of large- and small-scale forcings. In general, the schemes are able to capture the timing of surface precipitation better than the actual amounts in the Langtang Valley, which are predominately underestimated, with the Morrison scheme showing the best agreement with the measured values. The schemes all show a large positive bias in incoming radiation. Analysis of the radar/lidar cloud product and hydrometeors from each of the schemes suggests that “cold-rain” processes are a key precipitation formation mechanism, which is also well represented by the Morrison scheme. As well as microphysical structure, both large-scale and localized forcings are also important for determining surface precipitation. © 2017. The Authors."
"15050523700;15047538100;36242447900;6602135370;","Effect of cloud microphysics on Indian summer monsoon precipitating clouds: A coupled climate modeling study",2017,"10.1002/2016JD026106","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017390574&doi=10.1002%2f2016JD026106&partnerID=40&md5=e051de3d1ca2ff4c65a1356b2083b5bf","The quest for one of the most dominant processes controlling the large-scale circulations in the tropics is unraveled. The impact of cloud microphysical processes is known to have effects on rainfall and local atmospheric thermodynamics; however, its effect on the prevailing mean circulations is not yet studied. Two sets of coupled global climate model experiments (ICE and NO ICE microphysics) reveal that ice microphysics improves the strength of the Hadley circulation with respect to observation. Results pinpoint that ICE simulation enhances high cloud fraction (global tropics: ~59%, India: ~51%) and stratiform rain (global tropics: ~5%, India: ~15%) contribution. ICE and NO ICE cloud microphysics impacts differently on the outgoing longwave radiation (OLR), tropospheric temperature, and surface shortwave and longwave radiation. The effect of ice microphysics reduces OLR, which signifies deeper convection in the ICE run. The global annual average of the net radiation flux (shortwave and longwave) at the surface in ICE run (108.1W/m2) is close to the observation (106W/m2), which is overestimated in NO ICE run (112W/m2). The result of apparent heat source term over the land and ocean surface eventually modifies regional Hadley circulation. Thus, the effect of ice microphysics in the global coupled model is important not only because of microphysics but also due to the radiation feedbacks. Therefore, better ice-phase microphysics is required in the new generation of climate forecast model, which may lead to improvements in the simulation of monsoon. © 2017. American Geophysical Union. All Rights Reserved."
"16645127300;8953038700;55235148400;8570871900;57191574757;55343037000;","Running climate model on a commercial cloud computing environment: A case study using Community Earth System Model (CESM) on Amazon AWS",2017,"10.1016/j.cageo.2016.09.014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991619950&doi=10.1016%2fj.cageo.2016.09.014&partnerID=40&md5=24ea88cdd3feacf1d60d3d90ab5b89c3","The suites of numerical models used for simulating climate of our planet are usually run on dedicated high-performance computing (HPC) resources. This study investigates an alternative to the usual approach, i.e. carrying out climate model simulations on commercially available cloud computing environment. We test the performance and reliability of running the CESM (Community Earth System Model), a flagship climate model in the United States developed by the National Center for Atmospheric Research (NCAR), on Amazon Web Service (AWS) EC2, the cloud computing environment by Amazon.com, Inc. StarCluster is used to create virtual computing cluster on the AWS EC2 for the CESM simulations. The wall-clock time for one year of CESM simulation on the AWS EC2 virtual cluster is comparable to the time spent for the same simulation on a local dedicated high-performance computing cluster with InfiniBand connections. The CESM simulation can be efficiently scaled with the number of CPU cores on the AWS EC2 virtual cluster environment up to 64 cores. For the standard configuration of the CESM at a spatial resolution of 1.9° latitude by 2.5° longitude, increasing the number of cores from 16 to 64 reduces the wall-clock running time by more than 50% and the scaling is nearly linear. Beyond 64 cores, the communication latency starts to outweigh the benefit of distributed computing and the parallel speedup becomes nearly unchanged. © 2016 Elsevier Ltd"
"55809947500;36018685200;55467448100;55619292519;36810942300;42561913500;","Building Model as a Service to support geosciences",2017,"10.1016/j.compenvurbsys.2014.06.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84904226059&doi=10.1016%2fj.compenvurbsys.2014.06.004&partnerID=40&md5=e9ef56d8466b2a9d149e36818bf61cd4","Modeling is a fundamental methodology for simulating the past, understanding the present and predicting the future of the geospatial systems and phenomena. However, modeling in the geospatial science poses several challenges, including complex model setup, repetition in model setup, requirement for large, scalable computing resources, and management of a large amount of model output. To address these challenges, we propose Model as a Service (MaaS) by leveraging the latest advancement of cloud computing. MaaS enables various geoscience models to be published as services, and these services can be accessed through a simple web interface. MaaS automates the processes of configuring machines, setting up and running models, and managing model outputs. The computing resources are automatically provisioned by MaaS in a cloud environment. A proof-of-concept MaaS prototype is presented using a global climate change model (ModelE). Experimental results show that the MaaS prototype significantly simplifies model setup, accelerates model simulation and enhances model output by providing a web-based, on-demand, scalable modeling environment. © 2014 Elsevier Ltd"
"24390528000;6602600408;35611334800;24485834000;","Black carbon indirect radiative effects in a climate model",2017,"10.1080/16000889.2017.1369342","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048909905&doi=10.1080%2f16000889.2017.1369342&partnerID=40&md5=cf153aac5188437b7d4f2982eb2320dc","The aerosol–cloud interactions due to black carbon (BC) aerosols, as well as the implied climate responses, are examined using an aerosol module in the coupled atmosphere–ocean general circulation model MPI-ESM. BC is simulated to enhance cloud droplet number concentration (CDNC) by 10–15% in the BC emission source regions, especially in the Tropics and mid-latitudes. Higher CDNC and reduced auto-conversion from cloud water to rain water explains the increased cloud water path over the tropical regions (30◦S–30◦N) in the model. In the global mean, the cloud water– as well as precipitation changes are negligibly small. The global-mean effective radiative forcing due to aerosol–cloud interactions for BC is estimated at −0.13 ± 0.1Wm−2, which is attributable to the increase in CDNC burden and (regionally) cloud water in the model. Global mean temperature and rainfall response were found to be−0.16 ± 0.04K and−0.004±0.004mmday−1, respectively, with significantly larger regional changes mainly in the downwind regions from BC sources. © 2017, © 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group."
"57195198884;8953662800;57200702127;7403564495;56722821200;57206424059;55153585300;56610914500;57189621839;7404165281;55543826100;","Warming effect of dust aerosols modulated by overlapping clouds below",2017,"10.1016/j.atmosenv.2017.07.036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026404506&doi=10.1016%2fj.atmosenv.2017.07.036&partnerID=40&md5=3e446ed34f50141df1383f3515b6fc99","Due to the substantial warming effect of dust aerosols overlying clouds and its poor representation in climate models, it is imperative to accurately quantify the direct radiative forcing (DRF) of above-cloud dust aerosols. When absorbing aerosol layers are located above clouds, the warming effect of aerosols strongly depends on the cloud macro- and micro-physical properties underneath, such as cloud optical depth and cloud fraction at visible wavelength. A larger aerosol-cloud overlap is believed to cause a larger warming effect of absorbing aerosols, but the influence of overlapping cloud fraction and cloud optical depth remains to be explored. In this study, the impact of overlapping cloud properties on the shortwave all-sky DRF due to springtime above-cloud dust aerosols is quantified over northern Pacific Ocean based on 10-year satellite measurements. On average, the DRF is roughly 0.62 Wm−2. Furthermore, the warming effect of dust aerosols linearly increases with both overlapping cloud fraction and cloud optical depth. An increase of 1% in overlapping cloud fraction will amplify this warming effect by 1.11 Wm−2τ−1. For the springtime northern Pacific Ocean, top-of-atmosphere cooling by dust aerosols turns into warming when overlapping cloud fraction is beyond 0.20. The variation of critical cloud optical depth beyond which dust aerosols switch from exerting a net cooling to a net warming effect depends on the concurrent overlapping cloud fraction. When the overlapping cloud coverage range increases from 0.2 to –0.4 to 0.6–0.8, the corresponding critical cloud optical depth reduces from 6.92 to 1.16. Our results demonstrate the importance of overlapping cloud properties for determining the springtime warming effect of dust aerosols. © 2017 Elsevier Ltd"
"56035170100;24074765200;6602420251;56962763800;15832503400;56560167400;","Diversity on subtropical and polar cirrus clouds properties as derived from both ground-based lidars and CALIPSO/CALIOP measurements",2017,"10.1016/j.atmosres.2016.08.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984979111&doi=10.1016%2fj.atmosres.2016.08.015&partnerID=40&md5=112df61606a13c86f56cf1ba6ea3faf0","Cirrus (Ci) cloud properties can change significantly from place to place over the globe as a result of weather processes, reflecting their likely different radiative and climate implications. In this work Cirrus clouds (Ci) features observed in late autumn/early winter season at both subtropical and polar latitudes are examined and compared to CALIPSO/CALIOP observations. Lidar measurements were carried out in three stations: São Paulo (MSP, Brazil) and Tenerife (SCO, Canary Islands, Spain), as subtropical sites, and the polar Belgrano II base (BEL, Argentina) in the Antarctic continent. The backscattering ratio (BSR) profiles and the top and base heights of the Ci layers together to their Cirrus Cloud Optical Depth (CCOD) and Lidar Ratio (LR) for Ci clouds were derived. In addition, temperatures at the top and base boundaries of the Ci clouds were also obtained from local radiosoundings to verify pure ice Ci clouds occurrence using a given temperature top threshold (<− 38 °C). Ci clouds observed along the day were assembled in groups based on their predominant CCOD, and classified according to four CCOD-based categories. Ci clouds were found to be vertically-distributed in relation with the temperature, forming subvisual Ci clouds at lower temperatures and higher altitudes than other Ci categories at both latitudes. Discrepancies shown on LR values for the three stations, but mainly remarked between subtropical and polar cases, can be associated to different temperature regimes for Ci formation, influencing the internal ice habits of the Ci clouds, and hence likely affecting the LR derived for the Ci layer. In comparison with literature values, daily mean CCOD/LR for SCO (0.4 ± 0.4/21 ± 10 sr), MSP (0.5 ± 0.5/27 ± 5 sr) and BEL (0.2 ± 0.3/28 ± 9 sr) are in good agreement; however, the variability of the Ci optical features along the day present large discrepancies. In comparison with CALIOP data, Ci clouds are observed at similar altitudes (around 10–13 km height); however, differences are found mostly in CCOD values for subtropical Ci clouds, whereas LR values are in a closer agreement. These differences are carefully examined in relation with the closest CALIPSO overpass time and distance from the station (> 70 km far), inferring the irregular extension and inhomogeneity of the Ci clouds over each study area. These considerations can be useful for assimilation of the Ci features into climate models and evaluation of future space-borne lidar observations of Ci clouds, especially for the future ESA/Copernicus-Sentinel and ESA/EarthCARE missions. © 2016 Elsevier B.V."
"35171143600;","Atmospheric K-feldspar as a potential climate modulating agent through geologic time",2017,"10.1130/G38684.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015147893&doi=10.1130%2fG38684.1&partnerID=40&md5=e74ffb9233b67e937069a0ee8c214b12","Clouds and aerosols have a large, yet highly uncertain, effect on changes in Earth's climate. A factor of particular note is the role played by ice-nucleating particles, which remains poorly understood. The mineral K-feldspar (Kfs) has recently been shown by a number of independent studies to nucleate ice in mixed-phase cloud conditions far more efficiently than other common minerals. Here, global atmospheric Kfs flux through geologic time is estimated; constrained by records of secular continental crust and biosphere evolution, plate tectonics, volcanism, glaciation, and attendant trends in land surface stability. The analysis reveals that Kfs flux today is at neither extreme of the range estimated across geological time. The present-day Kfs flux, however, is likely to be among the most spatially and temporally variable due to land surface change. The concept of an ice-nucleation efficiency factor that can be calculated from rocks, and also eolian sediments and soils, is proposed. This allows the impact of paleo-atmospheric dust to be estimated through the rock record alongside meteorological and atmospheric composition considerations. With the reasonable assumption that the ice-nucleating properties of Kfs are themselves independent of the background climate state, a better understanding of Kfs flux across a range of spatial and temporal scales will advance understanding of climate processes and interactions. © 2017 The Authors."
"6603730198;23037063200;6701738452;7101748780;36056399500;35098801000;57193438291;55688930000;","Local atmospheric response to an open-ocean polynya in a high-resolution climate model",2017,"10.1175/JCLI-D-16-0120.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014002424&doi=10.1175%2fJCLI-D-16-0120.1&partnerID=40&md5=990dc2de56bb96bf83e73d1090c79cc5","In this paper the atmospheric response to an open-ocean polynya in the Southern Ocean is studied by analyzing the results from an atmospheric and oceanic synoptic-scale resolving Community Earth System Model (CESM) simulation.While coarser-resolution versions of CESMgenerally do not produce open-ocean polynyas in the SouthernOcean, they do emerge and disappear on interannual time scales in the synoptic-scale simulation.This provides an ideal opportunity to study the polynya's impact on the overlying and surrounding atmosphere.This has been pursued here by investigating the seasonal cycle of differences of surface and air-column variables between polynya and nonpolynya years. The results indicate significant local impacts on turbulent heat fluxes, precipitation, cloud characteristics, and radiative fluxes. In particular, it is found that clouds over polynyas are optically thicker and higher than clouds over sea ice during nonpolynya years. Although the lower albedo of polynyas significantly increases the net shortwave absorption, the enhanced cloud brightness tempers this increase by almost 50%. Also, in this model, enhanced longwave radiation emitted from the warmer surface of polynyas is balanced by stronger downwelling fluxes from the thicker cloud deck. Impacts are found to be sensitive to the synopticwind direction. The strongest regional impacts are foundwhen northeasterlywinds cross the polynya and interact with katabatic winds. Surface air pressure anomalies over the polynya are only found to be significant when cold, dry air masses strike over the polynya (i.e., in the case of southerly winds). © 2017 American Meteorological Society."
"55462884000;36538539800;","Impact of future climate policy scenarios on air quality and aerosol-cloud interactions using an advanced version of CESM/CAM5: Part II. Future trend analysis and impacts of projected anthropogenic emissions",2017,"10.1016/j.atmosenv.2016.12.034","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009136692&doi=10.1016%2fj.atmosenv.2016.12.034&partnerID=40&md5=c8da550870fc44976d09247501e5f0a6","Following a comprehensive evaluation of the Community Earth System Model modified at the North Carolina State University (CESM-NCSU), Part II describes the projected changes in the future state of the atmosphere under the representative concentration partway scenarios (RCP4.5 and 8.5) by 2100 for the 2050 time frame and examine the impact of climate change on future air quality under both scenarios, and the impact of projected emission changes under the RCP4.5 scenario on future climate through aerosol direct and indirect effects. Both the RCP4.5 and RCP8.5 simulations predict similar changes in air quality by the 2050 period due to declining emissions under both scenarios. The largest differences occur in O3which decreases by global mean of 1.4 ppb under RCP4.5 but increases by global mean of 2.3 ppb under RCP8.5 due to differences in methane levels, and PM10, which decreases by global mean of 1.2 μg m−3under RCP4.5 and increases by global mean of 0.2 μg m−3under RCP8.5 due to differences in dust and sea-salt emissions under both scenarios. Enhancements in cloud formation in the Arctic and Southern Ocean and increases of aerosol optical depth (AOD) in central Africa and South Asia dominate the change in surface radiation in both scenarios, leading to global average dimming of 1.1 W m−2and 2.0 W m−2in the RCP4.5 and RCP8.5 scenarios, respectively. Declines in AOD, cloud formation, and cloud optical thickness from reductions of emissions of primary aerosols and aerosol precursors under RCP4.5 result in near surface warming of 0.2 °C from a global average increase of 0.7 W m−2in surface downwelling solar radiation. This warming leads to a weakening of the Walker Circulation in the tropics, leading to significant changes in cloud and precipitation that mirror a shift in climate towards the negative phase of the El Nino Southern Oscillation. © 2016 Elsevier Ltd"
"56682032300;13405658600;","Important global and regional differences in aerosol cloud-albedo effect estimates between simulations with and without prognostic aerosol microphysics",2017,"10.1002/2016JD025886","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017420458&doi=10.1002%2f2016JD025886&partnerID=40&md5=2687e45eb5f5a9384c60b0c31f71f36b","Aerosol-cloud interactions are among the most uncertain climate forcings, in part due to the strong sensitivity of cloud droplet number concentration (CDNC) to changes in the size distribution of potential cloud condensation nuclei. Despite this sensitivity of simulated aerosol-cloud interactions to variations in size-resolved aerosol concentrations being well established, many chemistry-climate and chemical-transport models do not include explicit treatment of the aerosol size distribution. We use a global chemical-transport model to estimate the aerosol cloud-albedo effect (CAE) due to anthropogenic emissions with prognostic sectional aerosol microphysics and compare this to the CAE calculated when the simulated aerosol mass of each species is remapped onto a prescribed size distribution. We find that although both the prescribed and prognostic methods compare similarly well with present-day size-distribution observations, there are substantial differences in the relative CDNC and CAE due to anthropogenic emissions. When using the prognostic size-distribution method, anthropogenic emissions yield a 25-75% larger increase in CDNC over most land masses but a 50-75% smaller increase in some remote-marine regions than in the prescribed size-distribution methods. Simulations using the prognostic scheme yield a global mean anthropogenic CAE of -0.87 W m-2, while the simulations with the prescribed scheme predict -0.66 W m-2. In South America and South Asia, differences in the CAE exceed 3.0 W m-2. These differences suggest that simulations with prescribed size-distribution mapping are unable to capture regional and temporal variability in size-resolved aerosol number and thus may lead to biases in estimates of the CAE. © 2017. American Geophysical Union. All Rights Reserved."
"57195219129;7101959253;55087038900;","The diurnal cycle of clouds and precipitation at the ARM SGP site: Cloud radar observations and simulations from the multiscale modeling framework",2017,"10.1002/2016JD026353","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026310144&doi=10.1002%2f2016JD026353&partnerID=40&md5=1231c9867d15afd39ee98909c0bc6b56","Millimeter Wavelength Cloud Radar (MMCR) data from December 1996 to December 2010, collected at the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program Southern Great Plains (SGP) site, are used to examine the diurnal cycle of hydrometeor occurrence. These data are categorized into clouds (-40 dBZe ≤ reflectivity &lt; -10 dBZe), drizzle and light precipitation (-10 dBZe ≤ reflectivity &lt; 10 dBZe), and heavy precipitation (reflectivity ≥ 10 dBZe). The same criteria are implemented for the observation-equivalent reflectivity calculated by feeding outputs from a Multiscale Modeling Framework (MMF) climate model into a radar simulator. The MMF model consists of the National Center for Atmospheric Research Community Atmosphere Model with conventional cloud parameterizations replaced by a cloud-resolving model. We find that a radar simulator combined with the simple reflectivity categories can be an effective approach for evaluating diurnal variations in model hydrometeor occurrence. It is shown that the MMF only marginally captures observed increases in the occurrence of boundary layer clouds after sunrise in spring and autumn and does not capture diurnal changes in boundary layer clouds during the summer. Above the boundary layer, the MMF captures reasonably well diurnal variations in the vertical structure of clouds and light and heavy precipitation in the summer but not in the spring. © 2017. The Authors."
"12040335900;25723417400;7402085600;7006614696;57194553129;55890394800;55814053500;","Revisiting the iris effect of tropical cirrus clouds with trmm and a-train satellite data",2017,"10.1002/2016JD025827","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020785188&doi=10.1002%2f2016JD025827&partnerID=40&md5=5112221dc3ce3ea33d483449bd8a58b3","Just as the iris of human eye controls the light influx (iris effect), tropical anvil cirrus clouds may regulate the Earth’s surface warming by controlling outgoing longwave radiation. This study examines this possible effect with monthly satellite observations such as Tropical Rainfall Measuring Mission (TRMM) precipitation, Moderate Resolution Imaging Spectroradiometer cirrus fraction, and Clouds and the Earth’s Radiant Energy System top-of-the-atmosphere radiative fluxes averaged over different tropical domains from March 2000 to October 2014. To confirm that high-level cirrus is relevant to this study, Cloud-Aerosol Lidar with Orthogonal Polarization high cloud observations were also analyzed from June 2006 to December 2015. Our analysis revealed that the increase in sea surface temperature in the tropical western Pacific tends to concentrate convective cloud systems. This concentration effect very likely induces the significant reduction of both stratiform rain rate and cirrus fraction, without appreciable change in the convective rain rate. This reduction of stratiform rain rate and cirrus fraction cannot be found over its subregion or the tropical eastern Pacific, where the concentration effect of anvil cirrus is weak. Consistently, over the tropical western Pacific, the higher ratio of convective rain rate to total rain rate (i.e., precipitation efficiency) significantly correlates with warmer sea surface temperature and lower cirrus fraction. The reduced cirrus eventually increased outgoing longwave radiation to a greater degree than absorbed solar radiation. Finally, the negative relationship between precipitation efficiency and cirrus fraction tends to correspond to a low global equilibrium climate sensitivity in the models in the Coupled Model Intercomparison Project Phase 5. This suggests that tropical anvil cirrus clouds exert a negative climate feedback in strong association with precipitation efficiency. © 2017. American Geophysical Union. All Rights Reserved."
"7004854393;21740519000;","A short review of numerical cloud-resolving models",2017,"10.1080/16000870.2017.1373578","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048010213&doi=10.1080%2f16000870.2017.1373578&partnerID=40&md5=1d9368f85ff064f65a372a8a8787131f","A cloud-resolving model (CRM) allows performing numerical simulations of convective clouds, such as shallow cumulus and stratocumulus, or storms and squall-lines with a resolution on the order of a few tens of metres to a few kilometres over a limited-area 4D (time and space) domain. The development of such models over the past decades is reviewed and their specific features are presented. The latter include a non-hydrostatic dynamic and parameterizations of sub-grid turbulence, microphysical and radiative processes. The capabilities of such models are discussed based on comparisons with observations and model-intercomparison studies. CRMs are used in a variety of ways, from the exploration of cloud phenomenology and process-understanding studies to the development of algorithms for satellite products, as well as to address climate issues and to develop convective and cloud parametrizations for large-scale weather and climate models. A few results illustrating this wide utilization are presented. The continuous increase of computer power induces rapid changes in modelling perspectives and therefore, influences the developments and applications of CRMs. This is discussed together with emerging scientific questions which will further benefit from CRM simulations. © 2017, © 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group."
"40661026900;57194682120;55495632500;57200695323;57200697273;57194683790;","Spatial and Temporal Features of the Frequency of Cloud Occurrence over China Based on CALIOP",2017,"10.1155/2017/4548357","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042226472&doi=10.1155%2f2017%2f4548357&partnerID=40&md5=f5cdaf9ad1242fca99bcdab47f230bbe","Spatial and temporal distribution of cloud vertical structure are key components of global climate change. The occurrence of clouds over China and its surrounding areas has been calculated based on cloud layer products from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) at 1 km resolution. Results show significant regional differences in the frequency of cloud occurrence. Fewer clouds are found over the Mongolian Plateau and northern Indian Peninsula, with more clouds apparent over tropical seas and southern China. Cloud cover at night is slightly higher than during the day. Single-layer clouds are more common than multilayer clouds in most areas. In most areas, high-level cloud accounts for the largest proportion of single-layer clouds. The occurrence of clouds in summer and autumn is generally greater than in spring and winter. Single-layer clouds over the Mongolian Plateau and northern Indian Peninsula occur less frequently than multilayer clouds, especially in winter. Furthermore, single-layer clouds are common over the eastern part of southwest China all year round. Over parts of the Tibetan Plateau in summer, high clouds account for the largest proportion (>35%) of annual single-layer clouds, as a result of topography and enhanced summer convection. © 2017 Hongke Cai et al."
"55628190300;7007010459;","Regional modelling of rainfall erosivity: sensitivity of soil erosion to aerosol emissions",2017,"10.1002/qj.2919","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006256482&doi=10.1002%2fqj.2919&partnerID=40&md5=8ae82822814ebc2152e11fc465902f35","A rainfall erosivity scheme is implemented into the widely used regional atmosphere–land model, WRF. Rainfall erosivity is parametrized from hourly precipitation and surface runoff in a high resolution (4 km) convection-permitting model. The scheme is used to examine the potential effects of changes in atmospheric aerosol concentrations on soil erosion in a case-study of northern India and the surrounding countries for the 2010 monsoon season, using a model which isolates the indirect effect on cloud microphysics only. This study offers a preliminary investigation into this emerging topic, but longer simulations would be needed to establish a robust signal. Summer precipitation is reduced in most areas and the monsoon circulation weakens for increases in cloud condensation nuclei concentrations. This can be attributed to localised cloud microphysical changes in the northeast of India, which induce a dynamic response opposing the monsoon circulation. The two regions of greatest decrease in erosion with increasing aerosol are in the Western Ghats and the Ganges Delta, both significant cropland areas. However, the effect is not uniform, with isolated local increases in soil erosion. These results suggest that, while efforts to reduce anthropogenic aerosol emissions may improve water availability for crops through enhanced rainfall, these benefits are likely to be tempered by an increase in soil erosion, though robust local changes were difficult to predict. © 2016 Royal Meteorological Society"
"56707416400;57219982553;57193221521;57193220368;","Aerosol PSD and occurrence frequencies of clouds in the equatorial area",2017,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011931014&partnerID=40&md5=ee1e3015cde6ba96848f08648967edd9","Cloud play a very important role on climate but still not fully understood, we present in this work the data analysis of the clouds optical depth (COD) collected by AERONET network across 5 stations distributed around the equator. Occurrence frequencies of clouds are in direct relation with the frequencies of registered cloud optical depth. The characterization of these allows best understanding of their implication on regional and then on global radiation budget. The knowledge of the cloud optical depth define the classification of clouds according to their densities, from the overall occurrence frequency histograms we deduce that the equatorial zone is characterized by high density clouds (> 45%). The volume aerosol PSD is limited to accumulation and coarse mode with respectively median diameters 0.19 and 3.02 μm as average of all studied equatorial sites. The site of Nauru has large amplitude of the mainly coarse mode considered as a reference site for the equatorial area."
"56604613900;55720362700;55913139000;7003438566;56604445500;55964480200;","Analysis of aerosol-cloud-precipitation interactions based on MODIS data",2017,"10.1016/j.asr.2016.08.042","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006339816&doi=10.1016%2fj.asr.2016.08.042&partnerID=40&md5=66e3be477fa831dd97d2679a2fd81ea0","Aerosols exert an indirect impact on climate change via its impact on clouds by altering its radiative and optical properties which, in turn, changes the process of precipitation. Over recent years how to study the indirect climate effect of aerosols has become an important research topic. In this study we attempted to understand the complex mutual interactions among aerosols, clouds and precipitation through analysis of the spatial correlation between aerosol optical depth (AOD), cloud effective radius (CER) and precipitation during 2000–2012 in central-eastern China that has one of the highest concentrations of aerosols globally. With the assistance of moderate resolution imaging spectroradiometer (MODIS)-derived aerosol and cloud product data, this analysis focuses on regional differentiation and seasonal variation of the correlation in which in situ observed precipitation was incorporated. On the basis of the achieved results, we proposed four patterns depicting the mutual interactions between aerosols, clouds and precipitation. They characterize the indirect effects of aerosols on the regional scale. These effects can be summarized as complex seasonal variations and north-south regional differentiation over the study area. The relationship between AOD and CER is predominated mostly by the first indirect effect (the negative correlation between AOD and CER) in the north of the study area in the winter and spring seasons, and over the entire study area in the summer season. The relationship between CER and precipitation is dominated chiefly by the second indirect effect (the positive correlation between CER and precipitation) in the northern area in summer and over the entire study area in autumn. It must be noted that aerosols are not the factor affecting clouds and rainfall singularly. It is the joint effect of aerosols with other factors such as atmospheric dynamics that governs the variation in clouds and rainfall. © 2016 COSPAR"
"55462884000;56612517400;36538539800;","Impact of future climate policy scenarios on air quality and aerosol-cloud interactions using an advanced version of CESM/CAM5: Part I. model evaluation for the current decadal simulations",2017,"10.1016/j.atmosenv.2016.12.035","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007452347&doi=10.1016%2fj.atmosenv.2016.12.035&partnerID=40&md5=71ff1f23fc5e41415791d2702cfdcd0a","A version of the Community Earth System Model modified at the North Carolina State University (CESM-NCSU) is used to simulate the current and future atmosphere following the representative concentration partway scenarios for stabilization of radiative forcing at 4.5 W m−2(RCP4.5) and radiative forcing of 8.5 W m−2(RCP8.5). Part I describes the results from a comprehensive evaluation of current decadal simulations. Radiation and most meteorological variables are well simulated in CESM-NCSU. Cloud parameters are not as well simulated due in part to the tuning of model radiation and general biases in cloud variables common to all global chemistry-climate models. The concentrations of most inorganic aerosol species (i.e., SO42-, NH4+, and NO3−) are well simulated with normalized mean biases (NMBs) typically less than 20%. However, some notable exceptions are European NH4+, which is overpredicted by 33.0–42.2% due to high NH3emissions and irreversible coarse mode condensation, and Cl−, that is negatively impacted by errors in emissions driven by wind speed and overpredicted HNO3. Carbonaceous aerosols are largely underpredicted following the RCP scenarios due to low emissions of black carbon, organic carbon, and anthropogenic volatile compounds in the RCP inventory and efficient wet removal. This results in underpredictions of PM2.5and PM10by 6.4–55.7%. The column mass abundances are reasonably well simulated. Larger biases occur in surface mixing ratios of trace gases in CESM-NCSU, likely due to numerical diffusion from the coarse grid spacing of the CESM-NCSU simulations or errors in the magnitudes and vertical structure of emissions. This is especially true for SO2and NO2. The mixing ratio of O3is overpredicted by 38.9–76.0% due to the limitations in the O3deposition scheme used in CESM and insufficient titration resulted from large underpredictions in NO2. Despite these limitations, CESM-NCSU reproduces reasonably well the current atmosphere in terms of radiation, clouds, meteorology, trace gases, aerosols, and aerosol-cloud interactions, making it suitable for future climate simulations. © 2016 Elsevier Ltd"
"57193170261;6602600408;35611334800;35227762400;","Effects of diabatic and adiabatic processes on relative humidity in a GCM, and relationship between mid-tropospheric vertical wind and cloud-forming and cloud-dissipating processes",2017,"10.1080/16000870.2016.1272753","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015214440&doi=10.1080%2f16000870.2016.1272753&partnerID=40&md5=5b0913d8c0d70f4914f3199a63102e9b","Clouds play an important role in weather and climate. Therefore, it is important to quantify the dominant processes that influence cloud formation and dissolution. In this study, diagnostics of the relative humidity tendency in the ECHAM6 GCM are used to quantify the contribution of different atmospheric processes to the change in relative humidity and thus to quantify their impact on clouds. In the model, we find that the dominant processes are stratiform cloud microphysics, large-scale adiabatic horizontal advection and vertical motion, and cumulus convection. Tendencies calculated based on monthly mean fields approximate the monthly averages of instantaneous tendencies to within 50% in the mid-latitudes and 25% elsewhere. The correlation between the relative humidity tendencies and mid-tropospheric vertical velocity ω500 is analysed. The most important processes for cloud formation are tightly correlated with ω500; the monthly mean vertical velocity in most cases appears qualitatively useful to characterise the cloud-forming and cloud-dissipating processes. © 2017 The Author(s)."
"55606974300;55802246600;56075881200;55476830600;7003666669;7006270084;56384704800;","Quantification of marine aerosol subgrid variability and its correlation with clouds based on high-resolution regional modeling",2017,"10.1002/2017JD026567","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020525029&doi=10.1002%2f2017JD026567&partnerID=40&md5=84c7c0f07bda2daed87a3a03f717f3ad","One limitation of most global climate models (GCMs) is that with the horizontal resolutions they typically employ, they cannot resolve the subgrid variability (SGV) of clouds and aerosols, adding extra uncertainties to the aerosol radiative forcing estimation. To inform the development of an aerosol subgrid variability parameterization, here we analyze the aerosol SGV over the southern Pacific Ocean simulated by the high-resolution Weather Research and Forecasting model coupled to Chemistry. We find that within a typical GCM grid, the aerosol mass subgrid standard deviation is 15% of the grid-box mean mass near the surface on a 1 month mean basis. The fraction can increase to 50% in the free troposphere. The relationships between the sea-salt mass concentration, meteorological variables, and sea-salt emission rate are investigated in both the clear and cloudy portion. Under clear-sky conditions, marine aerosol subgrid standard deviation is highly correlated with the standard deviations of vertical velocity, cloud water mixing ratio, and sea-salt emission rates near the surface. It is also strongly connected to the grid box mean aerosol in the free troposphere (between 2 km and 4 km). In the cloudy area, interstitial sea-salt aerosol mass concentrations are smaller, but higher correlation is found between the subgrid standard deviations of aerosol mass and vertical velocity. Additionally, we find that decreasing the model grid resolution can reduce the marine aerosol SGV but strengthen the correlations between the aerosol SGV and the total water mixing ratio (sum of water vapor, cloud liquid, and cloud ice mixing ratios). © 2017. American Geophysical Union. All Rights Reserved."
"37025898200;7407797613;7006961728;7501760109;55220091300;","Impact of model physics on seasonal forecasts of surface air temperature in the arctic",2017,"10.1175/MWR-D-16-0272.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013891697&doi=10.1175%2fMWR-D-16-0272.1&partnerID=40&md5=213cb1255b86ab6836dd9f8e2cfaeb26","The impacts of model physics and initial sea ice thickness on seasonal forecasts of surface energy budget and air temperature in the Arctic during summer were investigated based on Climate Forecast System, version 2 (CFSv2), simulations. The model physics changes include the enabling of a marine stratus cloud scheme and the removal of the artificial upper limit on the bottom heat flux from ocean to sea ice. The impact of initial sea ice thickness was examined by initializing the model with relatively realistic sea ice thickness generated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS). Model outputs were compared to that from a control run that did not impose physics changes and used Climate Forecast System Reanalysis (CFSR) sea ice thickness. After applying the physics modification to either sea ice thickness initialization, the simulated total cloud cover more closely resembled the observed monthly variations of total cloud cover except for the midsummer reduction. Over the Chukchi-Bering Seas, the model physics modification reduced the seasonal forecast bias in surface air temperature by 24%. However, the use of initial PIOMAS sea ice thickness alone worsened the surface air temperature predictions. The experiment with physics modifications and initial PIOMAS sea ice thickness achieves the best surface air temperature improvement over the Chukchi-Bering Seas where the area-weighted forecast bias was reduced by 71% from 1.05Kdown to20.3K compared with the control run. This study supports other results that surface temperatures and sea ice characteristics are highly sensitive to the Arctic cloud and radiation formulations in models and need priority in model formulation and validation. © 2017 American Meteorological Society."
"23568239000;55917711400;","Large-Scale Analysis of Relationships between Mineral Dust, Ice Cloud Properties, and Precipitation from Satellite Observations Using a Bayesian Approach: Theoretical Basis and First Results for the Tropical Atlantic Ocean",2017,"10.1155/2017/5278120","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027247700&doi=10.1155%2f2017%2f5278120&partnerID=40&md5=bff268ed08c09cdc847b47e731549d7e","Mineral dust and ice cloud observations from the Infrared Atmospheric Sounding Interferometer (IASI) are used to assess the relationships between desert dust aerosols and ice clouds over the tropical Atlantic Ocean during the hurricane season 2008. Cloud property histograms are first adjusted for varying cloud top temperature or ice water path distributions with a Bayesian approach to account for meteorological constraints on the cloud variables. Then, histogram differences between dust load classes are used to describe the impact of dust load on cloud property statistics. The analysis of the histogram differences shows that ice crystal sizes are reduced with increasing aerosol load and ice cloud optical depth and ice water path are increased. The distributions of all three variables broaden and get less skewed in dusty environments. For ice crystal size the significant bimodality is reduced and the order of peaks is reversed. Moreover, it is shown that not only are distributions of ice cloud variables simply shifted linearly but also variance, skewness, and complexity of the cloud variable distributions are significantly affected. This implies that the whole cloud variable distributions have to be considered for indirect aerosol effects in any application for climate modelling. © 2017 Lars Klüser and Thomas Popp."
"56576520000;24173130300;6603431534;","Influences of drizzle on stratocumulus cloudiness and organization",2017,"10.1002/2017JD026641","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021829910&doi=10.1002%2f2017JD026641&partnerID=40&md5=9b34d0362eff792527297df6b01a2a4b","Large-eddy simulations are used to study the influence of drizzle on stratocumulus organization, based on measurements made as part of the Second Dynamics and Chemistry of the Marine Stratocumulus field study-II. Cloud droplet number concentration (Nc) is prescribed and considered as the proxy for different aerosol loadings. Our study shows that the amount of cloudiness does not decrease linearly with precipitation rate. An Nc threshold is observed below which the removal of cloud water via precipitation efficiently reduces cloud depth, allowing evaporation to become efficient and quickly remove the remaining thin clouds, facilitating a fast transition from closed cells to open cells. Using Fourier analysis, stratocumulus length scales are found to increase with drizzle rates. Raindrop evaporation below 300 m lowers the cloud bases and amplifies moisture variances in the subcloud layer, while it does not alter the horizontal scales in the cloud layer, suggesting that moist cold pool dynamic forcings are not essential for mesoscale organization of stratocumulus. The cloud scales are greatly increased when the boundary layer is too deep to maintain well mixed. © 2017. American Geophysical Union. All Rights Reserved."
"54783792600;7410041005;57217772325;35849722200;13403957300;","The occurrence of ice production in slightly supercooled Arctic stratiform clouds as observed by ground-based remote sensors at the ARM NSA site",2017,"10.1002/2016JD026226","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014307866&doi=10.1002%2f2016JD026226&partnerID=40&md5=25b84056bda15c42ceb65950e3525eae","Ice particle formation in slightly supercooled stratiform clouds is not well documented or understood. In this study, 4 years of combined lidar depolarization and radar reflectivity (Ze) measurements are analyzed to distinguish between cold drizzle and ice crystal formations in slightly supercooled Arctic stratiform clouds over the Atmospheric Radiation Measurement Program Climate Research Facility North Slope of Alaska Utqiaġvik (“Barrow”) site. Ice particles are detected and statistically shown to be responsible for the strong precipitation in slightly supercooled Arctic stratiform clouds at cloud top temperatures as high as 4°C. For ice precipitating Arctic stratiform clouds, the lidar particulate linear depolarization ratio (δpar_lin) correlates well with radar Ze at each temperature range, but the δpar_lin-Ze relationship varies with temperature ranges. In addition, lidar depolarization and radar Ze observations of ice generation characteristics in Arctic stratiform clouds are consistent with laboratory-measured temperature-dependent ice growth habits. © 2017. American Geophysical Union. All Rights Reserved."
"8533581200;6701469233;15041638200;26638689800;7006689582;25628505000;56879243400;","Climatology and interannual variability of cloudiness in the Atlantic Arctic from surface observations since the late nineteenth century",2017,"10.1175/JCLI-D-16-0329.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014579678&doi=10.1175%2fJCLI-D-16-0329.1&partnerID=40&md5=6c91ba23db88853b83e3029a883b10a4","A long-term climatology of cloudiness over the Norwegian, Barents, and Kara Seas (NBK) based on visual surface observations is presented. Annual mean total cloud cover (TCC) is almost equal over solid-ice (SI) and open-water (OW) regions of the NBK (73% ± 3% and 76% ± 2%, respectively). In general, TCC has higher intra- and interannual variability over SI than over OW. A decrease of TCC in the middle of the twentieth century and an increase in the last few decades was found at individual stations and for the NBK as a whole. In most cases these changes are statistically significant with magnitudes exceeding the data uncertainty that is associated with the surface observations. The most pronounced trends are observed in autumn when the largest changes to the sea ice concentration (SIC) occur. TCC over SI correlates significantly with SIC in the Barents Sea, with a statistically significant correlation coefficient between annual TCC and SIC of -0.38 for the period 1936-2013. Cloudiness over OW shows nonsignificant correlation with SIC. An overall increase in the frequency of broken and scattered cloud conditions and a decrease in the frequency of overcast and cloudless conditions were found over OW. These changes are statistically significant and likely to be connected with the long-term changes of morphological types (an increase of convective and a decrease of stratiform cloud amounts). © 2017 American Meteorological Society."
"55087038900;","Hadley cell widening in warming climate and implication to expansion of world dry lands",2017,"10.1142/9789814723541_0005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020238623&doi=10.1142%2f9789814723541_0005&partnerID=40&md5=878e0e82fbaf6158f4723ee004ec5c83","Observational analyses show that the Hadley cell has expanded by 2-5° latitudes over the past three decades. This expansion is also a robust feature of general circulation model (GCM) simulated climate changes in response to the increase of greenhouse gases but with a much slower rate. The Hadley cell widening has important implications for shifts in precipitation patterns that lead to the expansion of world dry land, and for the cloud feedback to the climate system. Reconciling the discrepancy in Hadley cell widening between the GCM simulations and observations and understanding the mechanisms responsible for this aspect of global climate change represent new challenges in climate research. © 2017 World Scientific Publishing Co. Pte. Ltd."
"57002856000;36161790500;","The role of cloud phase in Earth’s radiation budget",2017,"10.1002/2016JD025951","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014087612&doi=10.1002%2f2016JD025951&partnerID=40&md5=3c4400021621915cd2a81c67457f4301","The radiative impact of clouds strongly depends on their partitioning between liquid and ice phases. Until recently, however, it has been challenging to unambiguously discriminate cloud phase in a number of important global regimes. CloudSat and CALIPSO supply vertically resolved measurements necessary to identify clouds composed of both liquid and ice that are not easily detected using conventional passive sensors. The capability of these active sensors to discriminate cloud phase has been incorporated into the fifth generation of CloudSat’s 2B-FLXHR-LIDAR algorithm. Comparisons with Clouds and the Earth’s Radiant Energy System fluxes at the top of atmosphere reveal that an improved representation of cloud phase leads to better agreement compared to earlier versions of the algorithm. The RMS differences in annual mean outgoing longwave (LW) radiation gridded at 2.5° resolution are 4.9 W m-2, while RMS differences in outgoing shortwave (SW) are slightly larger at 8.9 W m-2 due to the larger diurnal range of solar insolation. This study documents the relative contributions of clouds composed of only liquid, only ice, and a combination of both phases to global and regional radiation budgets. It is found that mixed-phase clouds exert a global net cloud radiative effect of -3.4Wm-2, with contributions of -8.1Wm-2 and 4.7Wm-2 from SW and LW radiation, respectively. When compared with the effects of warm liquid clouds (-11.8Wm-2), ice clouds (3.5 W m-2), and multilayered clouds consisting of distinct liquid and ice layers (-4.6Wm-2), these results reinforce the notion that accurate representation of mixed-phase clouds is essential for quantifying cloud feedbacks in future climate scenarios. © 2017. American Geophysical Union. All Rights Reserved."
"55720588700;55790781000;56054435300;7004697990;37046755400;35425197200;","An efficient radiative transfer model for hyperspectral IR radiance simulation and applications under cloudysky conditions",2017,"10.1002/2016JD026273","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026447239&doi=10.1002%2f2016JD026273&partnerID=40&md5=53a821231383e7f98cb4ee70a0eccd59","An efficient radiative transfer model has been developed for hyperspectral infrared radiance simulation under both clear- and cloudy-sky conditions. The hyperspectral IR cloudy radiative transfer model (HIRTM) combines atmospheric transmittances due to molecular absorption and cloud absorption and scattering from cloud hydrometeors. An efficient analytical Jacobian methodology is also developed under both clear- and cloudy-sky conditions, which is needed both to assimilate cloudy radiances directly into numerical weather prediction models and to retrieve atmospheric soundings and cloud properties simultaneously from cloudy radiance measurements. In comparing HIRTM and its analytical Jacobian with the community radiative transfer model (CRTM), our research has shown that HIRTM’s Jacobian calculations are similar to those of CRTM. HIRTM and CRTM synthetic observations derived from model output are compared with corresponding real observations from Geostationary Operational Environmental Satellite 13 Imager observations, and both perform similarly under water clouds, while CRTM is colder than HIRTM for thick ice clouds. © 2017. American Geophysical Union. All Rights Reserved."
"56149492300;56003666300;36538539800;","Decadal application of WRF/chem for regional air quality and climate modeling over the U.S. under the representative concentration pathways scenarios. Part 2: Current vs. future simulations",2017,"10.1016/j.atmosenv.2016.12.028","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009280992&doi=10.1016%2fj.atmosenv.2016.12.028&partnerID=40&md5=5cc532a96f53bcacf6670038a3a1270d","Following a comprehensive model evaluation, this Part II paper presents projected changes in future (2046–2055) climate, air quality, and their interactions under the RCP4.5 and RCP8.5 scenarios using the Weather, Research and Forecasting model with Chemistry (WRF/Chem). In general, both WRF/Chem RCP4.5 and RCP8.5 simulations predict similar increases on average (∼2 °C) for 2-m temperature (T2) but different spatial distributions of the projected changes in T2, 2-m relative humidity, 10-m wind speed, precipitation, and planetary boundary layer height, due to differences in the spatial distributions of projected emissions, and their feedbacks into climate. Future O3mixing ratios will decrease for most parts of the U.S. under the RCP4.5 scenario but increase for all areas under the RCP8.5 scenario due to higher projected temperature, greenhouse gas concentrations and biogenic volatile organic compounds (VOC) emissions, higher O3values for boundary conditions, and disbenefit of NOxreduction and decreased NO titration over VOC-limited O3chemistry regions. Future PM2.5concentrations will decrease for both RCP4.5 and RCP8.5 scenarios with different trends in projected concentrations of individual PM species. Total cloud amounts decrease under both scenarios in the future due to decreases in PM and cloud droplet number concentration thus increased radiation. Those results illustrate the impacts of carbon policies with different degrees of emission reductions on future climate and air quality. The WRF/Chem and WRF simulations show different spatial patterns for projected changes in T2 for future decade, indicating different impacts of prognostic and prescribed gas/aerosol concentrations, respectively, on climate change. © 2016 Elsevier Ltd"
"56158622800;36451754500;57199033967;","Dust aerosols and aridity trends",2017,"10.1142/9789814723541_0009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020312974&doi=10.1142%2f9789814723541_0009&partnerID=40&md5=1a9e41c0399da211c59521a7bcea0214","Due to the large global extent of arid and semi-arid regions, mineral dust in the atmosphere and its interactions with clouds and precipitation can have a substantial impact on regional and global climate. Dust aerosols can influence the radiative energy budget directly by scattering and absorbing solar radiation and indirectly by acting as cloud condensation nuclei (CCN) and ice nuclei (IN). Dust aerosols can also inhibit or enhance precipitation to modify the hydrological cycle. Furthermore, dust aerosols can absorb solar radiation, contributing to adiabatic heating in the atmosphere that often enhances cloud evaporation. In this chapter, we attempt to provide a benchmark for our present understanding of the effects of dust aerosols on cloud and precipitation, primarily in Asian arid/semi-arid regions. © 2017 World Scientific Publishing Co. Pte. Ltd."
"56612517400;36538539800;56942554300;57213551855;7202048112;8511991900;56991611600;35792776400;55624488227;7004444634;7202010686;","Multi-year application of WRF-CAM5 over East Asia-Part I: Comprehensive evaluation and formation regimes of O3 and PM2.5",2017,"10.1016/j.atmosenv.2017.06.015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021320039&doi=10.1016%2fj.atmosenv.2017.06.015&partnerID=40&md5=3c38661eb0374928be02804caf3e7aac","Accurate simulations of air quality and climate require robust model parameterizations on regional and global scales. The Weather Research and Forecasting model with Chemistry version 3.4.1 has been coupled with physics packages from the Community Atmosphere Model version 5 (CAM5) (WRF-CAM5) to assess the robustness of the CAM5 physics package for regional modeling at higher grid resolutions than typical grid resolutions used in global modeling. In this two-part study, Part I describes the application and evaluation of WRF-CAM5 over East Asia at a horizontal resolution of 36-km for six years: 2001, 2005, 2006, 2008, 2010, and 2011. The simulations are evaluated comprehensively with a variety of datasets from surface networks, satellites, and aircraft. The results show that meteorology is relatively well simulated by WRF-CAM5. However, cloud variables are largely or moderately underpredicted, indicating uncertainties in the model treatments of dynamics, thermodynamics, and microphysics of clouds/ices as well as aerosol-cloud interactions. For chemical predictions, the tropospheric column abundances of CO, NO2, and O3 are well simulated, but those of SO2 and HCHO are moderately overpredicted, and the column HCHO/NO2 indicator is underpredicted. Large biases exist in the surface concentrations of CO, NOx, and PM10 due to uncertainties in the emissions as well as vertical mixing. The underpredictions of NO lead to insufficient O3 titration, thus O3 overpredictions. The model can generally reproduce the observed O3 and PM indicators. These indicators suggest to control NOx emissions throughout the year, and VOCs emissions in summer in big cities and in winter over North China Plain, North/South Korea, and Japan to reduce surface O3, and to control SO2, NH3, and NOx throughout the year to reduce inorganic surface PM. © 2017 Elsevier Ltd"
"26642547700;6603081424;22635081500;","Regime-based evaluation of cloudiness in CMIP5 models",2017,"10.1007/s00382-016-3064-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963748052&doi=10.1007%2fs00382-016-3064-0&partnerID=40&md5=8a2219f3b5b99ae1df3a7ede2651f9f3","The concept of cloud regimes (CRs) is used to develop a framework for evaluating the cloudiness of 12 fifth Coupled Model Intercomparison Project (CMIP5) models. Reference CRs come from existing global International Satellite Cloud Climatology Project (ISCCP) weather states. The evaluation is made possible by the implementation in several CMIP5 models of the ISCCP simulator generating in each grid cell daily joint histograms of cloud optical thickness and cloud top pressure. Model performance is assessed with several metrics such as CR global cloud fraction (CF), CR relative frequency of occurrence (RFO), their product [long-term average total cloud amount (TCA)], cross-correlations of CR RFO maps, and a metric of resemblance between model and ISCCP CRs. In terms of CR global RFO, arguably the most fundamental metric, the models perform unsatisfactorily overall, except for CRs representing thick storm clouds. Because model CR CF is internally constrained by our method, RFO discrepancies yield also substantial TCA errors. Our results support previous findings that CMIP5 models underestimate cloudiness. The multi-model mean performs well in matching observed RFO maps for many CRs, but is still not the best for this or other metrics. When overall performance across all CRs is assessed, some models, despite shortcomings, apparently outperform Moderate Resolution Imaging Spectroradiometer cloud observations evaluated against ISCCP like another model output. Lastly, contrasting cloud simulation performance against each model’s equilibrium climate sensitivity in order to gain insight on whether good cloud simulation pairs with particular values of this parameter, yields no clear conclusions. © 2016, Springer-Verlag Berlin Heidelberg."
"55614754800;8219958200;43061335300;35932420900;55326237100;6506594339;26424130900;22733332400;16444240700;24366038500;6508333712;22633429500;6507121473;57189214220;36917877800;56533742600;6603868770;23970271800;7004881313;14019543900;36486362800;57193234295;6603499076;57193242066;57193241144;55169203100;57190880917;57193251723;34769863200;24398842400;57193251302;7003510880;36339753800;36458602300;6602999057;37124186400;55274485000;7003922583;56506973700;57202531041;57190733403;54383910700;6602364115;16480992300;22935673400;23006117300;57193242459;6507442072;8701353900;22954523900;36705265400;55159696800;7004167838;55575920100;7201504886;15766838300;57191472753;6701806265;53980793000;57193235866;6602600408;","Large-eddy simulations over Germany using ICON: a comprehensive evaluation",2017,"10.1002/qj.2947","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011990301&doi=10.1002%2fqj.2947&partnerID=40&md5=573f5bb7fafeb05c588b8eace3feed03","Large-eddy simulations (LES) with the new ICOsahedral Non-hydrostatic atmosphere model (ICON) covering Germany are evaluated for four days in spring 2013 using observational data from various sources. Reference simulations with the established Consortium for Small-scale Modelling (COSMO) numerical weather prediction model and further standard LES codes are performed and used as a reference. This comprehensive evaluation approach covers multiple parameters and scales, focusing on boundary-layer variables, clouds and precipitation. The evaluation points to the need to work on parametrizations influencing the surface energy balance, and possibly on ice cloud microphysics. The central purpose for the development and application of ICON in the LES configuration is the use of simulation results to improve the understanding of moist processes, as well as their parametrization in climate models. The evaluation thus aims at building confidence in the model's ability to simulate small- to mesoscale variability in turbulence, clouds and precipitation. The results are encouraging: the high-resolution model matches the observed variability much better at small- to mesoscales than the coarser resolved reference model. In its highest grid resolution, the simulated turbulence profiles are realistic and column water vapour matches the observed temporal variability at short time-scales. Despite being somewhat too large and too frequent, small cumulus clouds are well represented in comparison with satellite data, as is the shape of the cloud size spectrum. Variability of cloud water matches the satellite observations much better in ICON than in the reference model. In this sense, it is concluded that the model is fit for the purpose of using its output for parametrization development, despite the potential to improve further some important aspects of processes that are also parametrized in the high-resolution model. © 2016 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"56315409000;34868367300;48061685100;","Color-Based Segmentation of Sky/Cloud Images from Ground-Based Cameras",2017,"10.1109/JSTARS.2016.2558474","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969528837&doi=10.1109%2fJSTARS.2016.2558474&partnerID=40&md5=22e3d736ad80f58a7f7b396d6d68a68c","Sky/cloud images captured by ground-based cameras (a.k.a. whole sky imagers) are increasingly used nowadays because of their applications in a number of fields, including climate modeling, weather prediction, renewable energy generation, and satellite communications. Due to the wide variety of cloud types and lighting conditions in such images, accurate and robust segmentation of clouds is challenging. In this paper, we present a supervised segmentation framework for ground-based sky/cloud images based on a systematic analysis of different color spaces and components, using partial least-squares regression. Unlike other state-of-The-Art methods, our proposed approach is entirely learning based and does not require any manually defined parameters. In addition, we release the Singapore whole Sky imaging segmentation database, a large database of annotated sky/cloud images, to the research community. © 2008-2012 IEEE."
"55214879200;7101959253;57206503877;7103271625;6701752471;6603171355;","Diagnosing cloud biases in the GFDL AM3 model with atmospheric classification",2017,"10.1002/2017JD027163","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037331594&doi=10.1002%2f2017JD027163&partnerID=40&md5=e42637ab91bc8ee9becb4f1e489bf690","We define a set of 21 atmospheric states, or recurring weather patterns, for a region surrounding the Atmospheric Radiation Measurement Program’s Southern Great Plains site using an iterative clustering technique. The states are defined using dynamic and thermodynamic variables from reanalysis, tested for statistical significance with cloud radar data from the Southern Great Plains site, and are determined every 6 h for 14 years, creating a time series of atmospheric state. The states represent the various stages of the progression of synoptic systems through the region (e.g., warm fronts, warm sectors, cold fronts, cold northerly advection, and high-pressure anticyclones) with a subset of states representing summertime conditions with varying degrees of convective activity. We use the states to classify output from the NOAA/Geophysical Fluid Dynamics Laboratory AM3 model to test the model’s simulation of the frequency of occurrence of the states and of the cloud occurrence during each state. The model roughly simulates the frequency of occurrence of the states but exhibits systematic cloud occurrence biases. Comparison of observed and model-simulated International Satellite Cloud Climatology Project histograms of cloud top pressure and optical thickness shows that the model lacks high thin cloud under all conditions, but biases in thick cloud are state-dependent. Frontal conditions in the model do not produce enough thick cloud, while fair-weather conditions produce too much. We find that increasing the horizontal resolution of the model improves the representation of thick clouds under all conditions but has little effect on high thin clouds. However, increasing resolution also changes the distribution of states, causing an increase in total cloud occurrence bias. © 2017. American Geophysical Union. All Rights Reserved."
"57194466775;6701832491;57193010470;7201375498;6701729202;6602551610;56298802300;57190177529;8909993500;","A comparison of the two arctic atmospheric winter states observed during N-ICE2015 and SHEBA",2017,"10.1002/2016JD025475","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020263311&doi=10.1002%2f2016JD025475&partnerID=40&md5=62fa0161bfaffcda8eee6a4a48c96635","Winter time atmospheric observations from the 2015 Norwegian young sea-ICE campaign (N-ICE2015) are compared with data from the 1997–1998 Surface Heat Budget of the Arctic (SHEBA) campaign. Both data sets have a bimodal distribution of the net longwave radiative flux for January–February, with modal values of -40 W m-2 and 0 Wm-2. These values correspond to the radiatively clear and opaquely cloudy states, respectively, and are likely to be representative of the wider Arctic. The new N-ICE2015 observations demonstrate that the two winter states operate in the Atlantic sector of the Arctic and regions of thin sea ice. We compare the N-ICE2015 and SHEBA data with ERA-Interim and output from the coupled Arctic regional climate model HIRHAM-NAOSIM. ERA-Interim simulates two Arctic winter states well and captures the timing of transitions from one state to the other, despite underestimating the cloud liquid water path. HIRHAM-NAOSIM has more cloud liquid water compared with ERA-Interim but simulates the two states poorly. Our results demonstrate that models must simulate realistic synoptic forcing and temperature profiles to accurately capture the two Arctic winter states, and not only the presence of mixed-phase clouds. Using ERA-Interim, we find a positive trend in the number of opaquely cloudy days in the western Atlantic sector of the Arctic, and a strong correlation with the mean winter temperature over much of the Arctic Basin. Hence, the two Arctic winter states are important for understanding interannual variability in the Arctic. The N-ICE2015 data set will help improve our understanding of these relationships. © 2016. American Geophysical Union. All Rights Reserved."
"8900751100;12345271600;56915049900;55816138400;36895628100;","Regional climate modeling of vegetation feedbacks on the Asian-Australian monsoon systems",2017,"10.1175/JCLI-D-16-0669.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014031316&doi=10.1175%2fJCLI-D-16-0669.1&partnerID=40&md5=b480c184a19e7ad0f16dcfa3ae4fd2a7","This study explores the hypothesis that subtropical and tropical monsoon regions exhibit unique responses to vegetation feedbacks. Using the Community Climate System Model (CCSM), M. Notaro et al. concluded that reduced vegetation cover led to an earlier subtropical Chinese monsoon and a delayed, weaker tropical Australian monsoon, yet significant climate and leaf area index (LAI) biases obfuscated the hypothesis's reliability. To address these concerns, the Regional Climate Model, version 4 (RegCM4), likewise coupled to the Community Land Model but with ''observed'' LAI boundary conditions, is applied across China and Australia. The model matches the observed dominance of crops, grass, and evergreen trees in southern China and grass and shrubs in northern Australia. The optimal model configuration is determined and applied in control runs for 1960-2013. Monsoon region LAI is modified in a RegCM4 ensemble, aimed at contrasting vegetation feedbacks between tropical and subtropical regions. Greater LAI supports reductions in albedo, temperature, wind speed, boundary layer height, ascending motion, and midlevel clouds and increases in diurnal temperature range (DTR), wind stress, evapotranspiration (ET), specific humidity, and low clouds. In response to greater LAI, rainfall is enhanced during Australia's pre-to-midmonsoon season but not for China. Modified LAI leads to dramatic changes in the temporal distribution and intensity of Australian rain events. Heterogeneous responses to biophysical feedbacks include amplified impacts (e.g., increased ET and DTR) across China's croplands and Australia's shrublands. Inconsistencies between China's monsoonal responses in the present RegCM4 study and prior CCSM study of M. Notaro et al. are attributed to CCSM's excessive forest cover and LAI, exaggerated roughness mechanism, and deficient ET response. © 2017 American Meteorological Society."
"35316223800;38662811700;26535318100;56102242900;56951371100;55934895100;35488207000;8545284000;9737845400;25223276500;55747667400;6701569174;7004260140;","Feasibility of Terrestrial laser scanning for collecting stem volume information from single trees",2017,"10.1016/j.isprsjprs.2016.11.012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85004009885&doi=10.1016%2fj.isprsjprs.2016.11.012&partnerID=40&md5=0b4003a21ed47406ad8baec761193369","Interest in measuring forest biomass and carbon stock has increased as a result of the United Nations Framework Convention on Climate Change, and sustainable planning of forest resources is therefore essential. Biomass and carbon stock estimates are based on the large area estimates of growing stock volume provided by national forest inventories (NFIs). The estimates for growing stock volume based on the NFIs depend on stem volume estimates of individual trees. Data collection for formulating stem volume and biomass models is challenging, because the amount of data required is considerable, and the fact that the detailed destructive measurements required to provide these data are laborious. Due to natural diversity, sample size for developing allometric models should be rather large. Terrestrial laser scanning (TLS) has proved to be an efficient tool for collecting information on tree stems. Therefore, we investigated how TLS data for deriving stem volume information from single trees should be collected. The broader context of the study was to determine the feasibility of replacing destructive and laborious field measurements, which have been needed for development of empirical stem volume models, with TLS. The aim of the study was to investigate the effect of the TLS data captured at various distance (i.e. corresponding 25%, 50%, 75% and 100% of tree height) on the accuracy of the stem volume derived. In addition, we examined how multiple TLS point cloud data acquired at various distances improved the results. Analysis was carried out with two ways when multiple point clouds were used: individual tree attributes were derived from separate point clouds and the volume was estimated based on these separate values (multiple-scan A), and point clouds were georeferenced as a combined point cloud from which the stem volume was estimated (multiple-scan B). This permitted us to deal with the practical aspects of TLS data collection and data processing for development of stem volume equations in boreal forests. The results indicated that a scanning distance of approximately 25% of tree height would be optimal for stem volume estimation with TLS if a single scan was utilized in boreal forest conditions studied here and scanning resolution employed. Larger distances increased the uncertainty, especially when the scanning distance was greater than approximately 50% of tree height, because the number of successfully measured diameters from the TLS point cloud was not sufficient for estimating the stem volume. When two TLS point clouds were utilized, the accuracy of stem volume estimates was improved: RMSE decreased from 12.4% to 6.8%. When two point clouds were processed separately (i.e. tree attributes were derived from separate point clouds and then combined) more accurate results were obtained; smaller RMSE and relative error were achieved compared to processing point clouds together (i.e. tree attributes were derived from a combined point cloud). TLS data collection and processing for the optimal setup in this study required only one sixth of time that was necessary to obtain the field reference. These results helped to further our knowledge on TLS in estimating stem volume in boreal forests studied here and brought us one step closer in providing best practices how a phase-shift TLS can be utilized in collecting data when developing stem volume models. © 2016"
"56543788800;18536452000;7403200489;55555084100;7003459101;57189470543;7201352328;","Impact of bacterial ice nucleating particles on weather predicted by a numerical weather prediction model",2017,"10.1016/j.atmosenv.2017.09.029","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030091379&doi=10.1016%2fj.atmosenv.2017.09.029&partnerID=40&md5=f8059422c214c34fdc59e6dc4c35b087","Bacterial ice-nucleating particles (INP) have the ability to facilitate ice nucleation from super-cooled cloud droplets at temperatures just below the melting point. Bacterial INP have been detected in cloud water, precipitation, and dry air, hence they may have an impact on weather and climate. In modeling studies, the potential impact of bacteria on ice nucleation and precipitation formation on global scale is still uncertain due to their small concentration compared to other types of INP, i.e. dust. Those earlier studies did not account for the yet undetected high concentration of nanoscale fragments of bacterial INP, which may be found free or attached to soil dust in the atmosphere. In this study, we investigate the sensitivity of modeled cloud ice, precipitation and global solar radiation in different weather scenarios to changes in the fraction of cloud droplets containing bacterial INP, regardless of their size. For this purpose, a module that calculates the probability of ice nucleation as a function of ice nucleation rate and bacterial INP fraction was developed and implemented in a numerical weather prediction model. The threshold value for the fraction of cloud droplets containing bacterial INP needed to produce a 1% increase in cloud ice was determined at 10−5 to 10−4. We also found that increasing this fraction causes a perturbation in the forecast, leading to significant differences in cloud ice and smaller differences in convective and total precipitation and in net solar radiation reaching the surface. These effects were most pronounced in local convective events. Our results show that bacterial INP can be considered as a trigger factor for precipitation, but not an enhancement factor. © 2017 Elsevier Ltd"
"56188826600;8210567900;6603812137;","Lightning jump as a nowcast predictor: Application to severe weather events in Catalonia",2017,"10.1016/j.atmosres.2016.08.021","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84985034438&doi=10.1016%2fj.atmosres.2016.08.021&partnerID=40&md5=50b135a013eceefd283781f16a62bac5","Several studies reported sudden increases in the total lightning flash rate (intra-cloud+cloud-to-ground) preceding the occurrence of severe weather (large hail, wind gusts associated to thunderstorms and/or tornadoes). Named “Lightning Jump”, this pattern has demonstrated to be of operational applicability in the forecasting of severe weather phenomena. The present study introduces the application of a lightning jump algorithm, with an identification of cells based solely on total lightning data, revealing that there is no need of radar data to trigger severe weather warnings. The algorithm was validated by means of a dataset severe weather events occurred in Catalonia in the period 2009–2014. Results obtained revealed very promising. © 2016 Elsevier B.V."
"55487986000;56537463000;57188556969;57188555505;7404829395;7401776640;7005973015;","An analysis of high cloud variability: imprints from the El Niño–Southern Oscillation",2017,"10.1007/s00382-016-3086-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961675516&doi=10.1007%2fs00382-016-3086-7&partnerID=40&md5=edeedb5208a4ed944e47cb1ee275c26f","Using data from the International Satellite Cloud Climatology Project (ISCCP), we examine how near-global (60°N–60°S) high cloud fraction varies over time in the past three decades. Our focus is on identifying dominant modes of variability and associated spatial patterns, and how they are related to sea surface temperature. By performing the principal component analysis, we find that the first two principal modes of high cloud distribution show strong imprints of the two types of El Niño–Southern Oscillation (ENSO)—the canonical ENSO and the ENSO Modoki. Comparisons between ISCCP data and 14 models from the Atmospheric Model Intercomparison Project Phase 5 (AMIP5) show that models simulate the spatial pattern and the temporal variations of high cloud fraction associated with the canonical ENSO very well but the magnitudes of the canonical ENSO vary among the models. Furthermore, the multi-model mean of the second principal mode in the AMIP5 simulations appears to capture the temporal behavior of the second mode but individual AMIP5 models show large discrepancies in capturing observed temporal variations. A new metric, defined by the relative variances of the first two principal components, suggests that most of the AMIP5 models overestimate the second principal mode of high clouds. © 2016, Springer-Verlag Berlin Heidelberg."
"7401800593;56861645000;8549269500;","Impact of aerosols and cloud parameters on Indian summer monsoon rain at intraseasonal scale: a diagnostic study",2017,"10.1007/s00704-015-1640-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84942040371&doi=10.1007%2fs00704-015-1640-6&partnerID=40&md5=ba0ab5054aed5c45e016f1ca4654f870","Aerosol and cloud parameters are known to be the influencing factors of the Indian summer monsoon rainfall (ISMR) variability at interannual and intraseasonal scales. In this study, we investigate the impact of remotely sensed aerosol optical depth and associated parameters (cloud fraction, cloud optical depth, cloud effective radii, cloud top pressure, and single-scattering albedo) on the individual active (break) spells of the Indian summer monsoon (ISM) season. Active and break spells are identified using satellite-derived data sets over the central Indian (CI) region. The present analysis suggests that the CI region is loaded with higher aerosol concentration and that rainfall is significantly negatively correlated with aerosol optical depth (significant at 1 % significance level) over CI. Contrary to the composite-based previous studies, it has been observed that the aerosol loading and cloud properties are considerably different during the individual active and break events. For break events, composite representation shows that aerosols are stacked along the Himalayan region while all individual break events do not portray this type of aerosol dispensation. It appears from the present analysis that the aerosols may impact the intraseasonal variability of ISMR through its indirect effect by altering the cloud properties and consequently the rainfall. Therefore, aerosols are supposed to be a regional contributor in affecting the intraseasonal variability of summer monsoon rainfall. © 2015, Springer-Verlag Wien."
"37661204200;35887352000;","Geotechnical measures for Uttarakhand flash flood-2013, India",2017,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014029099&partnerID=40&md5=c9a2c868ee73c08490e3148c032ea064","Many ""Run of the River"" projects in the North West part of Himalaya have been frequented by ""Cloud Burst"" induced flash flood in since 2009, which is primarily attributed to climate variability and land use pattern changes due to unregulated developmental perspectives against the rising demand of tourist related establishments. Given the ageing population of vulnerable constructions along the hilly terrains, safety issues require more attention in the form of technical auditing cum inspections, routine monitoring, emergency drills, surveillance systems, and regularly updated emergency action plans. Added to this accelerated events of ""cloud burst"" induced flash flood in the hilly region has opened up Dam safety issues, which are rather debated in the court of law for which geo-professional intervention are to be looked into. This paper explains the climatic and other geo-morphological changes that might have caused Uttarakhand Flash Flood-2013. Damages to the geotechnical structures in the form of excessive erosion, landslides, siltation of catchment area of several Dams in Uttarakhand state of India are described along with some illustration of landslides mitigation by simple bio-engineering solution as one the means of reconstruction measures across the state."
"56003666300;36538539800;56942554300;7202048112;8511991900;35792776400;55624488227;7202010686;","Evaluation of a multi-scale WRF-CAM5 simulation during the 2010 East Asian Summer Monsoon",2017,"10.1016/j.atmosenv.2017.09.008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029669799&doi=10.1016%2fj.atmosenv.2017.09.008&partnerID=40&md5=85a3649307199e61072cf35ae296af2c","The Weather Research and Forecasting model with Chemistry (WRF-Chem) with the physics package of the Community Atmosphere Model Version 5 (CAM5) has been applied at multiple scales over Eastern China (EC) and the Yangtze River Delta (YRD) to evaluate how increased horizontal resolution with physics designed for a coarser resolution climate model impacts aerosols and clouds, and the resulting precipitation characteristics and performance during the 2010 East Asian Summer Monsoon (EASM). Despite large underpredictions in surface aerosol concentrations and aerosol optical depth, there is good spatial agreement with surface observations of chemical predictions, and increasing spatial resolution tends to improve performance. Model bias and normalized root mean square values for precipitation predictions are relatively small, but there are significant differences when comparing modeled and observed probability density functions for precipitation in EC and YRD. Increasing model horizontal resolution tends to reduce model bias and error for precipitation predictions. The surface and column aerosol loading is maximized between about 32°N and 42°N in early to mid-May during the 2010 EASM, and then shifts north while decreasing in magnitude during July and August. Changing model resolution moderately changes the spatiotemporal relationships between aerosols, cloud properties, and precipitation during the EASM, thus demonstrating the importance of model grid resolution in simulating EASM circulation and rainfall patterns over EC and the YRD. Results from this work demonstrate the capability and limitations in the aerosol, cloud, and precipitation representation of WRF-CAM5 for regional-scale applications down to relatively fine horizontal resolutions. Further WRF-CAM5 model development and application in this area is needed. © 2017 Elsevier Ltd"
"56386678000;35622410000;7202408584;12242811400;6601974795;14052002000;23568239000;7103197356;55921064500;15071768600;7005456532;","Fast radiative transfer parameterisation for assessing the surface solar irradiance: The Heliosat-4 method",2017,"10.1127/metz/2016/0781","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013392702&doi=10.1127%2fmetz%2f2016%2f0781&partnerID=40&md5=61d41e3896d799fdf79d4cede56ec327","The new Heliosat-4 method estimates the downwelling shortwave irradiance received at ground level in all sky conditions. It provides the global irradiance and its direct and diffuse components on a horizontal plane and the direct irradiance for a plane normal to sun rays. It is a fully physical model using a fast, but still accurate approximation of radiative transfer modelling and is therefore well suited for geostationary satellite retrievals. It can also be used as a fast radiative transfer model in numerical weather prediction models. It is composed of two models based on abaci, also called look-up tables: the already-published McClear model calculating the irradiance under cloud-free conditions and the new McCloud model calculating the extinction of irradiance due to clouds. Both have been realized by using the libRadtran radiative transfer model. The main inputs to Heliosat-4 are aerosol properties, total column water vapour and ozone content as provided by the Copernicus Atmosphere Monitoring Service (CAMS) every 3 h. Cloud properties are derived from images of the Meteosat Second Generation (MSG) satellites in their 15 min temporal resolution using an adapted APOLLO (AVHRR Processing scheme Over cLouds, Land and Ocean) scheme. The 15 min means of irradiance estimated by Heliosat-4 are compared to corresponding measurements made at 13 stations within the Baseline Surface Radiation Network and being located in the field of view of MSG and in various climates. The bias for global irradiance is comprised between 2 and 32 W m-2. The root mean square error (RMSE) ranges between 74 and 94 W m-2. Relative RMSE values range between 15 % and 20 % of the mean observed irradiance for stations in desert and Mediterranean climates, and between 26 % and 43 % for rainy climates with mild winters. Correlation coefficients between 0.91 and 0.97 are found. The bias for the direct irradiance at normal incidence is comprised between-163 and +50 W m-2. The RMSE ranges from 160 W m-2 (29 % of the mean observed irradiance) to 288 W m-2 (63 %). The correlation coefficient ranges between 0.67 and 0.87. © 2016 The authors."
"57000421400;56231798500;","Fossil forest reveals sunspot activity in the early permian",2017,"10.1130/G38669.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014114379&doi=10.1130%2fG38669.1&partnerID=40&md5=e23acd06884e1f769a36c3f2bc913a60","Modern-day periodic climate pattern variations related to solar activity are well known. High-resolution records such as varves, ice cores, and tree-ring sequences are commonly used for reconstructing climatic variations in the younger geological history. For the first time we apply dendrochronological methods to Paleozoic trees in order to recognize annual variations. Large woody tree trunks from the early Permian Fossil Forest of Chemnitz, southeast Germany, show a regular cyclicity in tree-ring formation. The mean ring curve reveals a 10.62 yr cyclicity, the duration of which is almost identical to the modern 11 yr solar cycle. Therefore, we speculate and further discuss that, like today, sunspot activity caused fluctuations of cosmic radiation input to the atmosphere, affecting cloud formation and annual rates of precipitation, which are reflected in the tree-ring archive. This is the earliest record of sunspot cyclicity and simultaneously demonstrates its long-term stable periodicity for at least 300 m.y. © 2017, Geological Society of America. All right reserved."
"55878983900;25522765900;26028515700;39561656500;55663817800;35430463900;34769585100;","Ice water content-extinction relationships and effective diameter for TTL cirrus derived from in situ measurements during ATTREX 2014",2017,"10.1002/2016JD025948","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018720146&doi=10.1002%2f2016JD025948&partnerID=40&md5=cfe9bf0e211885df0c4a3808ac02ba4e","The NASA Airborne Tropical Tropopause Experiment (ATTREX) deployment in January-March 2014 yielded more than 34 h of cirrus cloud sampling in the tropical tropopause layer (TTL) over the western Pacific. Cirrus were encountered throughout the TTL, at temperatures between 185 and 207 K, with ice water content (IWC) ranging from &gt;10 mg m-3 to below the instrumental detection limit of 1 µg m-3. Geometric optical extinction (σ) values determined from cloud particle probe measurements ranged from 10-3 m-1 to &lt;10-7 m-1. The median effective diameter (Deff) for cirrus sampled at T &gt; 192 K was 40-50 µm and exhibited a weak temperature dependence, while colder than 192 K, Deff decreased more strongly with decreasing T. From the ATTREX data, a new parameterization of the IWC-σ relationship for TTL cirrus is derived that will improve the estimation of IWC from lidar and optical probe observations of these clouds. Plain Language Summary Cold, high-altitude tropical cirrus clouds are an important component of the climate system but are significantly underconstrained in climate models. Lidar measurements, especially from satellites, have the spatial and temporal coverage to produce statistically meaningful observations for model comparison and validation but do not directly measure quantities such as cloud ice water content that are important predicted quantities in the models. We have used an extensive data set of cloud ice water content and microphysical properties collected during a 2014 aircraft campaign in the western Pacific to derive a new parameterization that will improve the estimation of ice water content from lidar remote sensing measurements of tropical cirrus. With this parameterization, lidar observations can be used to derive a more accurate ice water content for tropical cirrus, in order to improve its treatment in models. © 2017. American Geophysical Union."
"55714908600;7003802133;7006354215;53979793000;55569698000;","Transient climate sensitivity depends on base climate ocean circulation",2017,"10.1175/JCLI-D-16-0581.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012273227&doi=10.1175%2fJCLI-D-16-0581.1&partnerID=40&md5=bf6cb150373257436f7ce6511cd1a553","There is large uncertainty in the simulation of transient climate sensitivity. This study aims to understand how such uncertainty is related to the simulation of the base climate by comparing two simulations with the same model but in which CO2 is increased from either a preindustrial (1860) or a present-day (1990) control simulation. This allows different base climate ocean circulations that are representative of those in current climate models to be imposed upon a single model. As a result, the model projects different transient climate sensitivities that are comparable to the multimodel spread. The greater warming in the 1990-start run occurs primarily at high latitudes and particularly over regions of oceanic convection. In the 1990-start run, ocean overturning circulations are initially weaker and weaken less from CO2 forcing. As a consequence, there are smaller reductions in the poleward ocean heat transport, leading to less tropical ocean heat storage and less moderated high-latitude surface warming. This process is evident in both hemispheres, with changes in the Atlantic meridional overturning circulation and the Antarctic Bottom Water formation dominating the warming differences in each hemisphere. The high-latitude warming in the 1990-start run is enhanced through albedo and cloud feedbacks, resulting in a smaller ocean heat uptake efficacy. The results highlight the importance of improving the base climate ocean circulation in order to provide a reasonable starting point for assessments of past climate change and the projection of future climate change. © 2017 American Meteorological Society."
"56457152000;7401796996;8629713500;56611366900;56898950300;7006783796;","Effects of environment forcing on marine boundary layer cloud-drizzle processes",2017,"10.1002/2016JD026326","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018538843&doi=10.1002%2f2016JD026326&partnerID=40&md5=9069257e43de27a50e4359f4ae1272d9","Determining the factors affecting drizzle formation in marine boundary layer (MBL) clouds remains a challenge for both observation and modeling communities. To investigate the roles of vertical wind shear and buoyancy (static instability) in drizzle formation, ground-based observations from the Atmospheric Radiation Measurement Program at the Azores are analyzed for two types of conditions. The type I clouds should last for at least 5 h and more than 90% time must be nondrizzling and then followed by at least 2 h of drizzling periods, while the type II clouds are characterized by mesoscale convection cellular structures with drizzle occur every 2 to 4 h. By analyzing the boundary layer wind profiles (direction and speed), it was found that either directional or speed shear is required to promote drizzle production in the type I clouds. Observations and a recent model study both suggest that vertical wind shear helps the production of turbulent kinetic energy (TKE), stimulates turbulence within cloud layer, and enhances drizzle formation near the cloud top. The type II clouds do not require strong wind shear to produce drizzle. The small values of lower tropospheric stability (LTS) and negative Richardson number (Ri) in the type II cases suggest that boundary layer instability plays an important role in TKE production and cloud-drizzle processes. By analyzing the relationships between LTS and wind shear for all cases and all time periods, a stronger connection was found between LTS and wind directional shear than that between LTS and wind speed shear. © 2017. American Geophysical Union."
"55721792100;7404516041;6602809980;35489518600;","Impact of long-range desert dust transport on hydrometeor formation over coastal East Asia",2017,"10.1007/s00376-016-6157-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003955292&doi=10.1007%2fs00376-016-6157-0&partnerID=40&md5=da38b3be637bdf96689ce2717bb29922","Model simulations and hydrological reanalysis data for 2007 are applied to investigate the impact of long-range desert dust transport on hydrometeor formation over coastal East Asia. Results are analyzed from Hong Kong and Shanghai, which are two representative coastal cities of East Asia. Long-range desert dust transport impacts mainly spring and summer clouds and precipitation over coastal East Asia. In spring, clouds and precipitation come mainly from large-scale condensation and are impacted mainly by dust from the Gobi, Sahara, and Thar deserts. These desert dusts can participate in the precipitation within and below the clouds. At lower latitudes, the dust particles act mainly as water nuclei. At higher latitudes, they act as both water nuclei and ice nuclei. The effect of Gobi, Sahara, and Thar dust on large-scale clouds and precipitation becomes stronger at higher latitudes. In summer, clouds and precipitation over coastal East Asia come mainly from convection and are impacted mainly by dust from the Taklamakan, Arabian, and Karakum-Kavir deserts. Most Taklamakan dust particles can participate in precipitation within convective clouds as ice nuclei, while Arabian and Karakum-Kavir dust particles participate only as water nuclei in precipitation below the clouds. The effect of Taklamakan dust on convective clouds and precipitation becomes stronger at lower latitudes. Of all the desert dusts, that from the Gobi and Taklamakan deserts has the relatively largest impact. Gobi dust impacts climate change in coastal East Asia by affecting spring water clouds at higher latitudes. © 2017, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg."
"35494005000;7202652226;","Diagnosing cloud microphysical process information from remote sensing measurements-A feasibility study using aircraft data. Part I: Tropical anvils measured during TC4",2017,"10.1175/JAMC-D-16-0083.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015228934&doi=10.1175%2fJAMC-D-16-0083.1&partnerID=40&md5=63df47b2c3b4eb297429545c21f7e489","The authors investigate whether radar remote sensing of a certain class of ice clouds allows for characterization of the precipitation rates and aggregation processes. The NASA DC-8 collected the measurements in tropical anvils during July and August 2007 as part of the Tropical Composition, Cloud and Climate Coupling (TC4) experiment. Measured hydrometeor size distributions are used to estimate precipitation rates (P) and to solve the hydrodynamical collection equation. These distributions are also used to estimate radar reflectivity factors (Z) and Doppler velocities (Vd) at W, Ka, and Ku bands. Optimal estimation techniques are then used to estimate the uncertainty in retrieving P and aggregation rates (A) from combinations of Z and Vd. It is found that diagnosing information about A requires significant averaging and that a dual-frequency combination of W and Ka bands seems to provide the most information for the ice clouds sampled during TC4. Furthermore, the addition of Vd with expected uncertainty contributes little to the microphysical retrieval of either P or A. It is also shown that accounting for uncertainty in ice microphysical bulk density dominates the retrieval uncertainty in both P and A causing, for instance, the instantaneous uncertainty in retrieved P to increase from ~30% to ~200%. © 2017 American Meteorological Society."
"55935714300;57211047073;57188725544;","Theoretical study of aerosols loading and retention over Bolgatanga, Ghana",2017,"10.1177/1178622117746995","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039743257&doi=10.1177%2f1178622117746995&partnerID=40&md5=862507f3f04c9efcf3caa44d62e8cf1a","The aerosols loading and retention over West Africa have grave effect on life-forms through the impact on health, farming, rainfall pattern, cloud formation, and regional climate. Bolgatanga can be found on the latitude and longitude of 10.78°N and 0.85°W, respectively. This research is focused on an investigative consideration of the negative effect of atmospheric aerosols over Bolgatanga in Ghana through a conceptual model using analytical and descriptive statistical methods with MATLAB curve-fitting tool. The model was verified using aerosol optical depth data set from satellite imagery—multi-angle imaging specto-reflectometer (MISR)—obtained over a period of 13 years. The highest percentage increase of aerosol retention was 64.27% over the research site. The model was used to estimate the atmospheric constants as 0.67, tuning constants as 0.24, and phase difference as ± π/4. The physical interpretation of the results was analyzed systematically. © The Author(s) 2017."
"56597037600;7006329853;7005453641;7202198678;16027966800;6701511321;","Comparing simulated PSC optical properties with CALIPSO observations during the 2010 Antarctic winter",2017,"10.1002/2016JD025191","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011002402&doi=10.1002%2f2016JD025191&partnerID=40&md5=45115463e33d1e7b4ee70e84cfc07339","We simulate polar stratospheric clouds (PSCs) during the Antarctic winter of 2010 using the Specified Dynamics version of the Whole Atmosphere Community Climate Model/Community Aerosol and Radiation Model for Atmospheres (SD-WACCM/CARMA) model. The current PSC model contains microphysical schemes for supercooled ternary solutions (STS) and nitric acid trihydrate (NAT) particles, as well as a prognostic treatment for PSC ice particles and dehydration. Our simulations and CALIPSO satellite data suggest two major NAT particle formation mechanisms. The first mechanism is the nucleation of NAT from STS. Our model, with homogeneous nucleation rates of NAT from STS constrained by observations from the Arctic winter of 2010–2011, reproduces optical properties observed by CALIPSO over Antarctica in May and the timing of denitrification observed by the Microwave Limb Sounder within their uncertainties. On the other hand, the CALIPSO data indicate that our simulations are missing clouds containing small NAT particles with large number densities. We suggest these particles are most likely to form from ice clouds or STS in gravity waves, as found by previous investigations. The simulated cloud coverage agrees with the CALIPSO cloud coverage within a few percent on average with a correlation coefficient of 0.83. However, using the CALIPSO classification algorithm, simulated ice clouds often fall into Mix categories under the denitrified and dehydrated conditions. The model needs an improved ice microphysical representation, not only to allow ice particles to be a source of NAT but also to provide information on ice cloud particle number and size so that ice cloud optical properties can be more precisely calculated for comparison with CALIPSO data. © 2017. American Geophysical Union. All Rights Reserved."
"57194593342;35278945900;8985856500;57189875591;55322939800;","Cloudiness regulates gross primary productivity of a poplar plantation under different environmental conditions",2017,"10.1139/cjfr-2016-0413","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021134394&doi=10.1139%2fcjfr-2016-0413&partnerID=40&md5=0b9d59d58a99e8b9d48af26b4315619c","Cloud cover regulates the gross primary productivity (GPP) of forest ecosystems by changing the radiation component and other environmental factors. In this study, we used an open-path eddy covariance system and microclimate sensors installed over a poplar plantation in northern China to measure the carbon exchange and climate variables during the mid-growing seasons (June to August) in 2014 and 2015. The results indicated that the GPP of the plantation peaked when the clearness index (CI) was between 0.45 and 0.65, at which point diffuse photosynthetically active radiation (PARdif) had reached its maximum. Cloudy skies increased the maximum ecosystem photosynthetic capacity (Pmax) by 28% compared with clear skies. PARdif and soil moisture were the most and the least crucial drivers for photosynthetic productivity of the plantation under cloudy skies, respectively. The ecosystem photosynthetic potential was higher under lower vapor pressure deficit (VPD &lt; 1.5 kPa), lower air temperature (Ta &lt; 30 °C), and nonstressed conditions (REW &gt; 0.4) for cloudy skies due to effects of Tal and VPD on stoma. Overall, our research highlighted the importance of cloud-induced radiation component change and environmental variation in quantifying the GPP of forest ecosystems. © 2017, Canadian Science Publishing. All rights reserved."
"57207486814;12645767500;8067118800;7202899330;56162305900;","An investigation of microphysics and subgrid-scale variability in warm-rain clouds using the A-train observations and a multiscale modeling framework",2017,"10.1002/2016JD026404","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027727674&doi=10.1002%2f2016JD026404&partnerID=40&md5=2247c11414064f563e4d6c4c4ace1b38","A common problem in climate models is that they are likely to produce rain at a faster rate than is observed and therefore produce too much light rain (e.g., drizzle). Interestingly, the Pacific Northwest National Laboratory (PNNL) multiscale modeling framework (MMF), whose warm-rain formation process is more realistic than other global models, has the opposite problem: the rain formation process in PNNL-MMF is less efficient than the real world. To better understand the microphysical processes in warm cloud, this study documents the model biases in PNNL-MMF and evaluates warm cloud properties, subgrid variability, and microphysics, using A-Train satellite observations to identify sources of model biases in PNNL-MMF. Like other models PNNL-MMF underpredicts the warm cloud fraction with compensating large optical depths. Associated with these compensating errors in cloudiness are compensating errors in the precipitation process. For a given liquid water path, clouds in the PNNL-MMF are less likely to produce rain than are real-world clouds. However, when the model does produce rain it is able to produce stronger precipitation than reality. As a result PNNL-MMF produces about the correct mean rain rate with an incorrect distribution of rates. The subgrid variability in PNNL-MMF is also tested, and results are fairly consistent with observations, suggesting that the possible sources of model biases are likely to be due to errors in its microphysics or dynamics rather than errors in the subgrid-scale variability produced by the embedded cloud resolving model. © 2017. American Geophysical Union."
"57203474818;11339581400;6701646252;57193276804;56008900500;8664477000;56808526800;57193274759;7102726801;57203772379;57193280634;","Role of persistent low-level clouds in mitigating air quality impacts of wintertime cold pool conditions",2017,"10.1016/j.atmosenv.2017.01.043","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012266396&doi=10.1016%2fj.atmosenv.2017.01.043&partnerID=40&md5=ed3adbf36de2fbb84f41156e78df2a5b","The Yakima Air Wintertime Nitrate Study (YAWNS) was conducted in January 2013 to investigate the drivers of elevated levels of fine particulate matter (PM2.5) frequently present in the region during winter stagnation periods. An extended stagnation period occurred during the study. For the first four days of the event, skies were clear and the strong diel variation in air pollution patterns were consistent with the expected effects of strong low-level nighttime temperature inversions with moderate mixing during daylight hours. Later in the event a low-level cloud layer formed that persisted over the Yakima Valley for the next seven days while regional conditions remained stagnant. Coincident with the onset of cloud, the levels of all measured primary pollutants, including CO2, CO, NOx, particle number concentration, and black carbon, dropped dramatically and remained low with negligible diel variation for as long as the cloud layer was present. The observed patterns for these air pollutants are consistent with decreased stability and enhanced mixing associated with the cloud-topped boundary layer. Interestingly, levels of secondary pollutants, most notably particulate ammonium nitrate, did not exhibit the same decline. This difference may be due to shifts in the chemical production of secondary pollutants during cloudy conditions, or may merely reflect a further influence of mixing. The results imply that the best strategies for managing wintertime air quality during episodes of persistent cloud are likely different from those needed during clear-sky stagnation events. © 2017"
"57130001200;6602403713;6508109309;8083993900;36975095600;8904533400;","Methods for comparing simulated and observed satellite infrared brightness temperatures and what do they tell us?",2017,"10.1175/WAF-D-16-0098.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010222422&doi=10.1175%2fWAF-D-16-0098.1&partnerID=40&md5=b80783d397ba7f7a73b6100633c40e1e","In this study, the utility of dimensioned, neighborhood-based, and object-based forecast verification metrics for cloud verification is assessed using output from the experimental High Resolution Rapid Refresh (HRRRx) model over a 1-day period containing different modes of convection. This is accomplished by comparing observed and simulated Geostationary Operational Environmental Satellite (GOES) 10.7-μm brightness temperatures (BTs). Traditional dimensioned metrics such as mean absolute error (MAE) and mean bias error (MBE) were used to assess the overall model accuracy. The MBE showed that the HRRRx BTs for forecast hours 0 and 1 are too warm compared with the observations, indicating a lack of cloud cover, but rapidly become too cold in subsequent hours because of the generation of excessive upper-level cloudiness. Neighborhood and object-based statistics were used to investigate the source of the HRRRx cloud cover errors. The neighborhood statistic fractions skill score (FSS) showed that displacement errors between cloud objects identified in the HRRRx and GOES BTs increased with time. Combined with the MBE, the FSS distinguished when changes in MAE were due to differences in the HRRRx BT bias or displacement in cloud features. The Method for Object-Based Diagnostic Evaluation (MODE) analyzed the similarity between HRRRx and GOES cloud features in shape and location. The similarity was summarized using the newly defined MODE composite score (MCS), an area-weighted calculation using the cloud feature match value from MODE. Combined with the FSS, the MCS indicated if HRRRx forecast error is the result of cloud shape, since the MCS is moderately large when forecast and observation objects are similar in size. © 2017 American Meteorological Society."
"54409650800;24281186100;57148462400;6602185497;6701773543;","Solar and thermal radiative effects during the 2011 extreme desert dust episode over Portugal",2017,"10.1016/j.atmosenv.2016.10.037","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84993966463&doi=10.1016%2fj.atmosenv.2016.10.037&partnerID=40&md5=1ada02a2533a7899ba6f3db3d43faa80","This paper analyses the influence of the extreme Saharan desert dust (DD) event on shortwave (SW) and longwave (LW) radiation at the EARLINET/AERONET Évora station (Southern Portugal) from 4 up to 7 April 2011. There was also some cloud occurrence in the period. In this context, it is essential to quantify the effect of cloud presence on aerosol radiative forcing. A radiative transfer model was initialized with aerosol optical properties, cloud vertical properties and meteorological atmospheric vertical profiles. The intercomparison between the instantaneous TOA shortwave and longwave fluxes derived using CERES and those calculated using SBDART, which was fed with aerosol extinction coefficients derived from the CALIPSO and lidar-PAOLI observations, varying OPAC dataset parameters, was reasonably acceptable within the standard deviations. The dust aerosol type that yields the best fit was found to be the mineral accumulation mode. Therefore, SBDART model constrained with the CERES observations can be used to reliably determine aerosol radiative forcing and heating rates. Aerosol radiative forcings and heating rates were derived in the SW (ARFSw, AHRSw) and LW (ARFLw, AHRLw) spectral ranges, considering a cloud-aerosol free reference atmosphere. We found that AOD at 440 nm increased by a factor of 5 on 6 April with respect to the lower dust load on 4 April. It was responsible by a strong cooling radiative effect pointed out by the ARFSw value (−99 W/m2 for a solar zenith angle of 60°) offset by a warming radiative effect according to ARFLw value (+21.9 W/m2) at the surface. Overall, about 24% and 12% of the dust solar radiative cooling effect is compensated by its longwave warming effect at the surface and at the top of the atmosphere, respectively. Hence, larger aerosol loads could enhance the response between the absorption and re-emission processes increasing the ARFLw with respect to those associated with moderate and low aerosol loads. The unprecedented results derived from this work complement the findings in other regions on the modifications of radiative energy budget by the dust aerosols, which could have relevant influences on the regional climate and will be topics for future investigations. © 2016 Elsevier Ltd"
"8225489800;7003398947;7006550762;16304488000;6603800142;7404297096;7004013316;","Climate responses to SATIRE and SIM-based spectral solar forcing in a 3D atmosphere-ocean coupled GCM",2017,"10.1051/swsc/2017009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018504018&doi=10.1051%2fswsc%2f2017009&partnerID=40&md5=13dae01b0cd0314835f67af896b06e57","We apply two reconstructed spectral solar forcing scenarios, one SIM (Spectral Irradiance Monitor) based, the other the SATIRE (Spectral And Total Irradiance REconstruction) modeled, as inputs to the GISS (Goddard Institute for Space Studies) GCMAM (Global Climate Middle Atmosphere Model) to examine climate responses on decadal to centennial time scales, focusing on quantifying the difference of climate response between the two solar forcing scenarios. We run the GCMAM for about 400 years with present day trace gas and aerosol for the two solar forcing inputs. We find that the SIM-based solar forcing induces much larger long-term response and 11-year variation in global averaged stratospheric temperature and column ozone. We find significant decreasing trends of planetary albedo for both forcing scenarios in the 400-year model runs. However the mechanisms for the decrease are very different. For SATIRE solar forcing, the decreasing trend of planetary albedo is associated with changes in cloud cover. For SIM-based solar forcing, without significant change in cloud cover on centennial and longer time scales, the apparent decreasing trend of planetary albedo is mainly due to out-of-phase variation in shortwave radiative forcing proxy (downwelling flux for wavelength >330 nm) and total solar irradiance (TSI). From the Maunder Minimum to present, global averaged annual mean surface air temperature has a response of ∼0.1 °C to SATIRE solar forcing compared to ∼0.04 °C to SIM-based solar forcing. For 11-year solar cycle, the global surface air temperature response has 3-year lagged response to either forcing scenario. The global surface air 11-year temperature response to SATIRE forcing is about 0.12 °C, similar to recent multi-model estimates, and comparable to the observational-based evidence. However, the global surface air temperature response to 11-year SIM-based solar forcing is insignificant and inconsistent with observation-based evidence. © G. Wen et al., Published by EDP Sciences 2017."
"14009790900;36678175000;7501535919;56309988000;24337227400;","Fine-scale climate change: modelling spatial variation in biologically meaningful rates of warming",2017,"10.1111/gcb.13343","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971632973&doi=10.1111%2fgcb.13343&partnerID=40&md5=9bbb29639521b573bc465987c9ffc305","The existence of fine-grain climate heterogeneity has prompted suggestions that species may be able to survive future climate change in pockets of suitable microclimate, termed ‘microrefugia’. However, evidence for microrefugia is hindered by lack of understanding of how rates of warming vary across a landscape. Here, we present a model that is applied to provide fine-grained, multidecadal estimates of temperature change based on the underlying physical processes that influence microclimate. Weather station and remotely derived environmental data were used to construct physical variables that capture the effects of terrain, sea surface temperatures, altitude and surface albedo on local temperatures, which were then calibrated statistically to derive gridded estimates of temperature. We apply the model to the Lizard Peninsula, United Kingdom, to provide accurate (mean error = 1.21 °C; RMS error = 1.63 °C) hourly estimates of temperature at a resolution of 100 m for the period 1977–2014. We show that rates of warming vary across a landscape primarily due to long-term trends in weather conditions. Total warming varied from 0.87 to 1.16 °C, with the slowest rates of warming evident on north-east-facing slopes. This variation contributed to substantial spatial heterogeneity in trends in bioclimatic variables: for example, the change in the length of the frost-free season varied from +11 to −54 days and the increase in annual growing degree-days from 51 to 267 °C days. Spatial variation in warming was caused primarily by a decrease in daytime cloud cover with a resulting increase in received solar radiation, and secondarily by a decrease in the strength of westerly winds, which has amplified the effects on temperature of solar radiation on west-facing slopes. We emphasize the importance of multidecadal trends in weather conditions in determining spatial variation in rates of warming, suggesting that locations experiencing least warming may not remain consistent under future climate change. © 2016 John Wiley & Sons Ltd"
"26638689800;6701469233;8533581200;25628505000;7004506673;","Diurnal asymmetry to the observed global warming",2017,"10.1002/joc.4688","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959420034&doi=10.1002%2fjoc.4688&partnerID=40&md5=c29b524b2322f6af6801beabcc7b6e1c","The observed warming of the surface air temperature (SAT) over the last 50 years has not been homogenous. There are strong differences in the temperature changes both geographically and on different time frames. Here, we review the observed diurnal asymmetry in the global warming trend: the night-time temperatures have increased more rapidly than day-time temperatures. Several explanations for this asymmetric warming have been offered in the literature. These generally relate differences in the temperature trends to regionalized feedback effects, such as changes to cloud cover, precipitation or soil moisture. Here, we discuss a complementary mechanism through which the planetary boundary layer (PBL) modulates the SAT response to changes in the surface energy balance. This reciprocal relationship between boundary-layer depth and temperature response can explain a part of why the night-time has warmed more rapidly than the daytime. We used a multi-linear regression model to compare the effect of the PBL, cloud cover, precipitation and soil moisture on the SAT. From this, we demonstrate that it is the boundary-layer depth which is the strongest predictor of the strength of temperature trends in the boreal annual cycle, and in all seasons except the summer. © 2016 The Authors. International Journal of Climatology published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"57202774763;15822958100;","The realism of stochastic weather generators in risk discovery",2017,"10.2495/WRM170231","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85049311435&doi=10.2495%2fWRM170231&partnerID=40&md5=08fd157c247e56d6802020f80f424f7a","Weather generators reproduce artificial climate time series that are commonly used for hydrological modeling and climate adaptation studies. To examine the representativeness of a stochastically generated climate time series, a novel stochastic method is suggested where these time series are projected in two spaces (the Climate Statistics Space - CSS; and the Risk and Performance Indicators Space - RPIS). A visual inspection as well as the Mahalanobis distance are used to assess the two spaces relative position and their proximity to the points representing the observations. The dimensions of the CSS are a subset of climate statistics, while the dimensions of the RPIS are a set of risk and performance indicators calculated using streamflow time series. A rainfall-runoff model is used to convert all climate time series from the CSS into streamflow time series in the RPIS. Three stochastic weather generators were used in this study: The Weather Generator École de Technologie Supérieure (WeaGETS), the Multisite Stochastic Weather Generator (MulGETS) using two different generation algorithms, and a k-nearest neighbour weather generator. Each generator was used to construct precipitation, maximum and minimum temperatures time series representing the historical period. The suggested approach was tested on a 41-years-long climate and flow time series from South Nation watershed in Eastern Ontario, Canada. The MulGETS model was able to perform well where the point representing the observations was centered inside the cloud of points representing the synthetic time series in some CSS. © 2017 WIT Press."
"55347084100;57192594710;53871776700;57200679067;6603948265;7004047498;7006595513;26434854300;","Effect of Prudhoe Bay emissions on atmospheric aerosol growth events observed in Utqiaġvik (Barrow), Alaska",2017,"10.1016/j.atmosenv.2016.12.019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006958987&doi=10.1016%2fj.atmosenv.2016.12.019&partnerID=40&md5=cfec2339cf7ca8c5e1816ca2f6273aab","The Arctic is a rapidly changing ecosystem, with complex aerosol-cloud-climate feedbacks contributing to more rapid warming of the region as compared to the mid-latitudes. Understanding changes to particle number concentration and size distributions is important to constraining estimates of the effect of anthropogenic activity on the region. During six years of semi-continuous measurements of particle number size distributions conducted near Utqiaġvik (Barrow), Alaska, 37 particle-growth events were observed. The majority of events occurred during spring and summer with a monthly maximum in June, similar to other Arctic sites. Based on backward air mass trajectory analysis, similar numbers of particle-growth events were influenced by marine (46%) and Prudhoe Bay air masses (33%), despite air primarily coming from the Arctic Ocean (75 ± 2% of days) compared to Prudhoe Bay (8 ± 2% of days). The corresponding normalized particle-growth event frequency suggests that emissions from Prudhoe Bay could induce an average of 92 particle-growth events, more than all other air mass sources combined, at Barrow annually. Prudhoe Bay is currently the third largest oil and gas field in the United States, and development in the Arctic region is expected to expand throughout the 21st century as the extent of summertime sea ice decreases. Elevated particle number concentrations due to human activity are likely to have profound impacts on climate change in the Arctic through direct, indirect, and surface albedo feedbacks, particularly through the addition of cloud condensation nuclei. © 2016 Elsevier Ltd"
"29067574800;15724418700;","On the discrepancies in tropical belt expansion between reanalyses and climate models and among tropical belt width metrics",2017,"10.1175/JCLI-D-16-0371.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012250199&doi=10.1175%2fJCLI-D-16-0371.1&partnerID=40&md5=bba451d0fd89083b18c3e226d42d0119","The arid subtropics are situated at the edges of the tropical belt, where subsidence in the Hadley cells suppresses precipitation. Any meridional shift in these edge latitudes could have significant impacts on surface climate. Recent studies have investigated past and future changes in the tropical belt width and have found discrepancies in the rates of expansion estimated with different metrics and between climate models and reanalyses. Here, CMIP5 simulations and four modern reanalyses are analyzed using an ensemble of objective tropical belt width metrics to reexamine if such inconsistencies exist. The authors do not find sufficient evidence to demonstrate this discrepancy between models and reanalyses, as reanalysis trends in the tropical belt width fall within the range of model trends for any given metric. Furthermore, only metrics based on the Hadley cells are found to exhibit robust historical and future expansion. Metrics based on the subtropical jet and the tropopause show no robust response. This differentiation may be due to the strong correlation, on all time scales, between the Hadley cell edge latitudes and the latitudes of the eddy-driven jets, which consistently shift poleward in response to radiative forcings. In contrast, the subtropical jet and tropopause metrics appear to be decoupled from the Hadley cells and the eddy-driven jets and essentially measure a different tropical belt. The tropical belt width metrics are inconsistently correlated with surface climate indices based on precipitation and surface evaporation. This may make assessing the surface impacts of observed and future tropical expansion challenging. © 2017 American Meteorological Society."
"7801444786;57139989000;","Temperature dependency of hourly precipitation intensities – surface versus cloud layer temperature",2017,"10.1002/joc.4678","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959160903&doi=10.1002%2fjoc.4678&partnerID=40&md5=8279b8de369e4cff0d843a5fa4c14116","Possible changes in precipitation intensity, especially for extreme precipitation events, in a warming climate are of great societal concern. It is generally expected that heavy precipitation will become more intense. The relationship between precipitation intensity and temperature and other factors influencing precipitation is not fully understood yet. Still, a robust estimate for a possible increase in precipitation intensity is of great importance for many applications, such as the planning of flood control or adaptations in agricultural systems. The Clausius-Clapeyron relation, which explains the dependency of the water holding capacity on air temperature, has been proposed as a possible constraint. It would yield an increase of about 7% K−1 warming (deemed the Clausius-Clapeyron rate). In this article, the relation between heavy 1-h precipitation and 2-m air temperature in observations from the recent past at the station in Vienna Austria is studied. Following a methodology outline in previous studies, this study will show that increases around the Clausius-Clapeyron rate are found with steeper increases towards the warm end. These findings confirm those of comparable studies. It remains unclear whether there is a limit to that scaling at a certain temperature because the results become unreliable at the warm end of the temperature range due to insufficient sample sizes. In a second step, the dependency of hourly precipitation extremes on the mean temperature between the 700 and 500 hPa layers is analysed in the same manner. A similar increase is found, but the results remain robust even in higher percentiles of the distribution of temperature values in the respective data sets. © 2016 Royal Meteorological Society"
"55747201700;56032594900;6507495053;6603423022;8669401600;6602577491;57203260074;6603180620;","The influence of synoptic circulations and local processes on temperature anomalies at three French observatories",2017,"10.1175/JAMC-D-16-0113.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009446833&doi=10.1175%2fJAMC-D-16-0113.1&partnerID=40&md5=ff0aa2885b0f4b4a8ca9fdb4b17d8d79","The relative contribution of the synoptic-scale circulations to local and mesoscale processes was quantified in terms of the variability of midlatitude temperature anomalies from 2003 to 2013 using meteorological variables collected from three French observatories and reanalyses. Four weather regimes were defined from sea level pressure anomalies using National Centers for Environmental Prediction reanalyses with a K-means algorithm. No correlation was found between daily temperature anomalies and weather regimes, and the variability of temperature anomalies within each regime was large. It was therefore not possible to evaluate the effect of large scales on temperature anomalies by this method. An alternative approach was found with the use of the analogs method: the principle being that for each day of the considered time series, a set of days that had a similar large-scale 500-hPa geopotential height field within a fixed domain was considered. The observed temperature anomalies were then compared with those observed during the analog days: the closer the two types of series are to each other, the greater is the influence of the large scale. This method highlights a widely predominant influence of the large-scale atmospheric circulation on the temperature anomalies. It showed a potentially larger influence of the Mediterranean Sea and orographic flow on the two southern observatories. Low-level cloud radiative effects substantially modulated the variability of the daily temperature anomalies."
"55706019000;55307621700;6603327055;","Impact of abrupt land cover changes by tropical deforestation on Southeast Asian climate and agriculture",2017,"10.1175/JCLI-D-16-0131.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015885898&doi=10.1175%2fJCLI-D-16-0131.1&partnerID=40&md5=6e2297542f67a448efb29aeea005939c","Southeast Asia (SE Asia) undergoes major and rapid land cover changes as a result of agricultural expansion. Landscape conversion results in alterations to surface fluxes of moisture, heat, and momentum and sequentially impact the boundary layer structure, cloud-cover regime, and all other aspects of local and regional weather and climate occurring also in regimes remote from the original landscape disturbance. The extent and magnitude of the anthropogenic modification effect is still uncertain. This study investigates the biogeophysical effects of large-scale deforestation on monsoon regions using an idealized deforestation simulation. The simulations are performed using the regional climate model COSMO-CLM forced with ERA-Interim data during the period 1984-2004. In the deforestation experiment, grasses in SE Asia, between 20°S and 20°N, replace areas covered by trees. Using principal component analysis, it is found that abrupt conversion from forest to grassland cover leads to major climate variability in the year of disturbance, which is 1990, over SE Asia. The persistent land modification leads to a decline in evapotranspiration and precipitation and a significant warming due to reduced latent heat flux during 1990-2004. The strongest effects are seen in the lowlands of SE Asia. Daily precipitation extremes increase during the monsoon period and ENSO, differing from the result of mean precipitation changes. Maximum temperature also increases by 2°C. The impacts of land cover change are more intense than the effects of El Niño and La Niña. In addition, results show that these land clearings can amplify the impact of the natural mode ENSO, which has a strong impact on climate conditions in SE Asia. This will likely have consequences for the agricultural output. © 2017 American Meteorological Society."
"24081949800;7004533232;57193441126;6603058638;57214815903;35955429700;","Improving the simulation of large lakes in regional climate modeling: Two-way lake-atmosphere coupling with a 3D hydrodynamic model of the great lakes",2017,"10.1175/JCLI-D-16-0225.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014004015&doi=10.1175%2fJCLI-D-16-0225.1&partnerID=40&md5=19ad12323114550f2396e91f834e122c","Accurate representations of lake-ice-atmosphere interactions in regional climatemodeling remain one of themost critical and unresolved issues for understanding large-lake ecosystems and their watersheds. To date, the representation of theGreat Lakes two-way interactions in regional climatemodels is achieved with one-dimensional (1D) lake models applied at the atmospheric model lake grid points distributed spatially across a 2D domain. While some progress has beenmade in refining 1D lake model processes, such models are fundamentally incapable of realistically resolving a number of physical processes in the Great Lakes. In this study, a two-way coupled 3D lake-ice-climate modeling system [Great Lakes-Atmosphere Regional Model (GLARM)] is developed to improve the simulation of large lakes in regional climate models and accurately resolve the hydroclimatic interactions. Model results are compared to a wide variety of observational data and demonstrate the unique skill of the coupled 3D modeling system in reproducing trends and variability in the Great Lakes regional climate, as well as in capturing the physical characteristics of the Great Lakes by fully resolving the lake hydrodynamics. Simulations of the climatology and spatiotemporal variability of lake thermal structure and ice are significantly improved over previous coupled, 1D simulations. At seasonal and annual time scales, differences inmodel results are primarily observed for variables that are directly affected by lake surface temperature (e.g., evaporation, precipitation, sensible heat flux) while no significant differences are found in other atmospheric variables (e.g., solar radiation, cloud cover). Underlying physical mechanisms for the simulation improvements using GLARM are also discussed. © 2017 American Meteorological Society."
"15071768600;7202060229;56901447500;","Verification of ECMWF and ECMWF/MACC's global and direct irradiance forecasts with respect to solar electricity production forecasts",2017,"10.1127/metz/2016/0676","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013356442&doi=10.1127%2fmetz%2f2016%2f0676&partnerID=40&md5=014bc5a1cb0f4658d8123da9937bef9d","The successful electricity grid integration of solar energy into day-ahead markets requires at least hourly resolved 48 h forecasts. Technologies as photovoltaics and non-concentrating solar thermal technologies make use of global horizontal irradiance (GHI) forecasts, while all concentrating technologies both from the photovoltaic and the thermal sector require direct normal irradiances (DNI). The European Centre for Medium-Range Weather Forecasts (ECMWF) has recently changed towards providing direct as well as global irradiances. Additionally, the MACC (Monitoring Atmospheric Composition & Climate) near-real time services provide daily analysis and forecasts of aerosol properties in preparation of the upcoming European Copernicus programme. The operational ECMWF/IFS (Integrated Forecast System) forecast system will in the medium term profit from the Copernicus service aerosol forecasts. Therefore, within the MACC-II project specific experiment runs were performed allowing for the assessment of the performance gain of these potential future capabilities. Also the potential impact of providing forecasts with hourly output resolution compared to three-hourly resolved forecasts is investigated. The inclusion of the new aerosol climatology in October 2003 improved both the GHI and DNI forecasts remarkably, while the change towards a new radiation scheme in 2007 only had minor and partly even unfavourable impacts on the performance indicators. For GHI, larger RMSE (root mean square error) values are found for broken/overcast conditions than for scattered cloud fields. For DNI, the findings are opposite with larger RMSE values for scattered clouds compared to overcast/broken cloud situations. The introduction of direct irradiances as an output parameter in the operational IFS version has not resulted in a general performance improvement with respect to biases and RMSE compared to the widely used SKARTVEIT et al. (1998) global to direct irradiance conversion scheme. Cloudy situations and especially thin ice cloud cases are forecasted much better with respect to biases and RMSE, but large biases are introduced in clear sky cases. When applying the MACC aerosol scheme to include aerosol direct effects, an improvement especially in DNI biases is found for cloud free cases as expected. However, a performance decrease is found for water cloud cases. It is assumed that this is caused by the lack of an explicit modelling of cloud-aerosol interactions, while other meteorological forcings for cloud processes like the temperature field are modified by the aerosols. © 2016 The authors."
"57213233110;24178021700;23979417900;","Change in snow depletion pattern in a river basin of Arunachal Pradesh under projected climatic scenarios",2017,"10.30955/gnj.002034","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030267144&doi=10.30955%2fgnj.002034&partnerID=40&md5=a265e09453be382a14331a9feabe1a61","Snow depletion curves (SDCs) are important in hydrological studies for predicting snowmelt generated runoff in high mountain catchments. The present study deals with the derivation of the average snow depletion pattern in the Mago basin of Arunachal Pradesh, which falls in the eastern Himalayan region and the generation of climate affected SDCs in future years (2020, 2030, 2040, and 2050) under different projected climatic scenarios. The MODIS daily snow cover product at 500m resolution from both the Aqua and Terra satellites was used to obtain daily snow cover maps. MOD10A1 and MYD10A1 images were compared to select cloud free or minimum cloud image to obtain the temporal distribution of snow cover area (SCA). Snow accumulation and depletion patterns were obtained by analysing SCA at different days. For most of the years, two peaks were observed in the SCA analysis. The conventional depletion curve (CDC) representing present climate was derived by determining and interpolating the SCA from cloud-free (cloud<5%) images for the selected hydrological year 2007. The investigation shows that the SCA was highest in February and lowest in May. Ten years meteorological data were used to normalize the temperature and precipitation data of the selected hydrological year (2007) to eliminate the impact of their yearly fluctuations on the snow cover depletion. The temperature and precipitation changes under four different projected climatic scenarios (A1B, A2, B1, and IPCC Commitment) were analysed for future years. Changes in the cumulative snowmelt depth with respect to the present climate for different future years were studied by a degree-day approach and were found to be highest under A1B, followed by A2, B1, and IPCC Commitment scenarios. It was observed that the A1B climatic scenario affected the depletion pattern most, making the depletion of snow to start and complete faster than under different scenarios. Advancing of depletion curve for different future years was found to be highest under A1B and lowest under IPCC Commitment scenarios with A2 and B1 in-between them. © 2017 Global NEST Printed in Greece. All rights reserved"
"36969949500;15724543600;7102447698;7102976560;7004214645;8846887600;12240390300;55126391900;7103206141;","Multimodel precipitation responses to removal of U.S. sulfur dioxide emissions",2017,"10.1002/2017JD026756","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019168257&doi=10.1002%2f2017JD026756&partnerID=40&md5=68d8ef526753173935550a45346f01d8","Emissions of aerosols and their precursors are declining due to policies enacted to protect human health, yet we currently lack a full understanding of the magnitude, spatiotemporal pattern, statistical significance, and physical mechanisms of precipitation responses to aerosol reductions. We quantify the global and regional precipitation responses to U.S. SO2 emission reductions using three fully coupled chemistry-climate models: Community Earth System Model version 1, Geophysical Fluid Dynamics Laboratory Coupled Model 3, and Goddard Institute for Space Studies ModelE2. We contrast 200 year (or longer) simulations in which anthropogenic U.S. sulfur dioxide (SO2) emissions are set to zero with present-day control simulations to assess the aerosol, cloud, and precipitation response to U.S. SO2 reductions. In all three models, reductions in aerosol optical depth up to 70% and cloud droplet number column concentration up to 60% occur over the eastern U.S. and extend over the Atlantic Ocean. Precipitation responses occur both locally and remotely, with the models consistently showing an increase in most regions considered. We find a northward shift of the tropical rain belt location of up to 0.35° latitude especially near the Sahel, where the rainy season length and intensity are significantly enhanced in two of the three models. This enhancement is the result of greater warming in the Northern versus Southern Hemispheres, which acts to shift the Intertropical Convergence Zone northward, delivering additional wet season rainfall to the Sahel. Two of our three models thus imply a previously unconsidered benefit of continued U.S. SO2 reductions for Sahel precipitation. © 2017. American Geophysical Union. All Rights Reserved."
"54083229500;35209683700;","Dynamical and thermodynamical impacts of high- and low-frequency atmospheric eddies on the initial melt of Arctic Sea Ice",2017,"10.1175/JCLI-D-15-0366.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010908085&doi=10.1175%2fJCLI-D-15-0366.1&partnerID=40&md5=4b664fcb7cc3c42e1719caa3d102f82c","The role of high-frequency and low-frequency eddies in the melt onset of Arctic sea ice is investigated through an examination of eddy effects on lower-tropospheric (1000-500 hPa) meridional heat transport into the Arctic and local surface downwelling shortwave and longwave radiation. Total and eddy components of the meridional heat transport into the Arctic from 1979 to 2012 are calculated from reanalysis data, and surface radiation data are acquired from the NASA Clouds and the Earth's Radiant Energy System (CERES) project dataset. There is a significant positive correlation between the mean initial melt date and the September sea ice minimum extent, with each quantity characterized by a negative trend. Spatially, the earlier mean melt onset date is primarily found in a region bounded by 90°E and 130°W. The decline in this region is steplike and not associated with an increase in meridional heat transport but with an earlier appearance of above-freezing temperatures in the troposphere. In most years, discrete short-duration episodes of melt onset over a large area occur. In an investigation of two of these melt episodes, a positive total meridional heat transport is associated with the peak melt, with the product of high-frequency eddy wind and mean temperature fields being the most important contributor. Additionally, there is a key positive anomaly in surface downwelling longwave radiation immediately preceding the peak melt that is associated with increased cloud cover and precipitable water. These results suggest the importance of carefully considering and properly representing atmospheric eddies when modeling the melt onset of Arctic sea ice."
"18437925900;27169114300;16487959800;","Connections between climatic characteristics and cyclonic activity in winter over Siberia in 1976–2011",2017,"10.1134/S1024856017010109","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015005090&doi=10.1134%2fS1024856017010109&partnerID=40&md5=951d518018a3f28e1dfcbbd45e47d805","The temperature, surface pressure, and cloud cover for Siberia (50°–70° N; 60°–110° E) in the winter period (December–February) are estimated over 1976–2011 based on data from 163 meteorological stations. Using surface synoptic maps, time series of winter cyclone characteristics, such as the total number and central pressure, are derived for the same period. Two time intervals are found in variations of climatic characteristics and cyclone activity characteristics: 1976–1990 and 1991–2011. In the first period, the temperature and cloud cover increased and the surface pressure fell, which reduced the number of cyclones and intensified (deepened) them. In the second period, opposite trends took place. The correlation analysis between the climate variables and cyclonic activity characteristics allowed us to consistently describe the impact of cyclones on the surface pressure and cloudiness. © 2017, Pleiades Publishing, Ltd."
"55866422100;6602974799;6602243604;","Impact of partitioning and oxidative processing of PAH in fogs and clouds on atmospheric lifetimes of PAH",2017,"10.1016/j.atmosenv.2017.04.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018484311&doi=10.1016%2fj.atmosenv.2017.04.016&partnerID=40&md5=eb4809c2fb3a4a191de865f05e96c1ce","The importance of the atmospheric aqueous phase of fogs and clouds, for the processing and removal of polycyclic aromatic hydrocarbons (PAHs) is not well known. A multiphase model was developed to determine the fate and lifetime of PAHs in fogs and clouds for a limited set of daytime conditions. The model describes partitioning between three phases (aqueous, liquid organic, and gas), experimental and estimated (photo)oxidation rates. Using a limited set of microphysical and chemical input conditions, the loss rates of PAHs in the complex three-phase system are explored. At 25 °C, PAHs with two, three and four rings are predicted to be primarily in the gas phase (fraction in the gas phase xg &gt; 90%) while five- and six-ring PAHs partition significantly into droplets with aqueous phase fractions of 1–6% and liquid organic phase fractions of 31–91%, respectively. The predicted atmospheric chemical lifetimes of PAHs in the presence of fog or cloud droplets (&lt;8 h) are significantly shorter than literature predictions of PAH lifetimes due to wet and dry deposition (1–14 days and 5–15 months, respectively) and shorter than or equal to predicted lifetimes due to chemical reactions in the gas and organic particulate phases (1–300 h). Even though PAH solubilities are ≤4 × 10−2 g L−1, the results of the current study show that often the condensed phase of fog and cloud droplets cannot be neglected as a PAH sink. © 2017 Elsevier Ltd"
"23476370700;7102989499;6602136577;","Cloud heights measured by MISR from 2000 to 2015",2017,"10.1002/2017JD026456","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017428546&doi=10.1002%2f2017JD026456&partnerID=40&md5=5be44e82c693732eb0413f0137aee67b","Davies and Molloy (2012) reported a decrease in the global effective cloud height over the first 10 years of Multiangle Imaging Spectroradiometer (MISR) measurements on the Terra satellite. We have reexamined their time series for possible artefacts that might especially affect the initial portion of the record when the heights appeared anomalously high. While variations in sampling were shown to be inconsequential, an artefact due to the change in equator crossing time that affected the first 2 years was discovered, and this has now been corrected. That correction, together with the extension of the time series by five more years, yields no significant overall trend in global heights during the first 15 years of Terra operation. The time series is dominated by large interannual fluctuations associated with La Niña events that mask any overall trend on a global scale. On a regional basis, the cloud heights showed significant interannual variations of much larger amplitude, sometimes with fairly direct cancellation between regions. There were unexplained differences between the two hemispheres in the timing of height anomalies. These differences persisted over a large range of extratropical latitudes, suggestive of teleconnections. Within the tropics, there were very strong changes associated with the Central Pacific and Indonesian Maritime Continent regions that oscillated out of phase with each other, with interannual amplitudes that exceeded 1 km. Plain Language Summary Effective cloud height is an important climate variable, strongly influencing the overall greenhouse effect, with a change of ≈15 m/decade being comparable to the rate of CO2 increase. The Multiangle Imaging Spectroradiometer (MISR) instrument on the Terra satellite uses a stereo technique to systematically measure cloud heights with a sampling accuracy of ≈11m on the global, annual average. Over the last 15 years we find interannual departures are greatest during La Niña events, reaching over 40m on a global average. The apparent decreasing trend during the first 10 years noted by Davies and Molloy has now vanished, in part due to correction for sun glint, and in part due to higher clouds in the last 5 years. Regional cloud height changes continue to show a high degree of correlation, especially for about five distinct regions of equatorial clouds. Southern Hemisphere cloud heights have increased, whereas Northern Hemisphere heights have decreased. © 2017. American Geophysical Union. All Rights Reserved."
"36018685200;55946208600;57054708700;56580738900;57189296641;","Utilizing Cloud Computing to address big geospatial data challenges",2017,"10.1016/j.compenvurbsys.2016.10.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85002871337&doi=10.1016%2fj.compenvurbsys.2016.10.010&partnerID=40&md5=a2c07db418d5ae41271b787baaab22c6","Big Data has emerged with new opportunities for research, development, innovation and business. It is characterized by the so-called four Vs: volume, velocity, veracity and variety and may bring significant value through the processing of Big Data. The transformation of Big Data's 4 Vs into the 5th (value) is a grand challenge for processing capacity. Cloud Computing has emerged as a new paradigm to provide computing as a utility service for addressing different processing needs with a) on demand services, b) pooled resources, c) elasticity, d) broad band access and e) measured services. The utility of delivering computing capability fosters a potential solution for the transformation of Big Data's 4 Vs into the 5th (value). This paper investigates how Cloud Computing can be utilized to address Big Data challenges to enable such transformation. We introduce and review four geospatial scientific examples, including climate studies, geospatial knowledge mining, land cover simulation, and dust storm modelling. The method is presented in a tabular framework as a guidance to leverage Cloud Computing for Big Data solutions. It is demostrated throught the four examples that the framework method supports the life cycle of Big Data processing, including management, access, mining analytics, simulation and forecasting. This tabular framework can also be referred as a guidance to develop potential solutions for other big geospatial data challenges and initiatives, such as smart cities. © 2016 The Authors"
"57193136041;35568218100;7801615894;7003719604;35229110700;","Lightning potential index performances in multimicrophysical cloud-resolving simulations of a back-building mesoscale convective system: The Genoa 2014 event",2017,"10.1002/2016JD026115","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018874960&doi=10.1002%2f2016JD026115&partnerID=40&md5=f939c32b112ce71ff15101ede957880c","Severe weather events are responsible for hundreds of fatalities and millions of euros of damage every year on the Mediterranean basin. Lightning activity is a characteristic phenomenon of severe weather and often accompanies torrential rainfall, which, under certain conditions like terrain type, slope, drainage, and soil saturation, may turn into flash flood. Building on the existing relationship between significant lightning activity and deep convection and precipitation, the performance of the Lightning Potential Index, as a measure of the potential for charge generation and separation that leads to lightning occurrence in clouds, is here evaluated for the V-shape back-building Mesoscale Convective System which hit Genoa city (Italy) in 2014. An ensemble of Weather Research and Forecasting simulations at cloud-permitting grid spacing (1 km) with different microphysical parameterizations is performed and compared to the available observational radar and lightning data. The results allow gaining a deeper understanding of the role of lightning phenomena in the predictability of V-shape back-building Mesoscale Convective Systems often producing flash flood over western Mediterranean complex topography areas. Moreover, they support the relevance of accurate lightning forecasting for the predictive ability of these severe events. © 2017. American Geophysical Union."
"9246029600;6602761005;23393212200;","Coupled high-latitude climate feedbacks and their impact on atmospheric heat transport",2017,"10.1175/JCLI-D-16-0324.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008178824&doi=10.1175%2fJCLI-D-16-0324.1&partnerID=40&md5=91f22616fdfeefd164c66ada6c8d7973","The response of atmospheric heat transport to anthropogenic warming is determined by the anomalous meridional energy gradient. Feedback analysis offers a characterization of that gradient and hence reveals how uncertainty in physical processes may translate into uncertainty in the circulation response. However, individual feedbacks do not act in isolation. Anomalies associated with one feedback may be compensated by another, as is the case for the positive water vapor and negative lapse rate feedbacks in the tropics. Here a set of idealized experiments are performed in an aquaplanet model to evaluate the coupling between the surface albedo feedback and other feedbacks, including the impact on atmospheric heat transport. In the tropics, the dynamical response manifests as changes in the intensity and structure of the overturning Hadley circulation. Only half of the range of Hadley cell weakening exhibited in these experiments is found to be attributable to imposed, systematic variations in the surface albedo feedback. Changes in extratropical clouds that accompany the albedo changes explain the remaining spread. The feedback-driven circulation changes are compensated by eddy energy flux changes, which reduce the overall spread among experiments. These findings have implications for the efficiency with which the climate system, including tropical circulation and the hydrological cycle, adjusts to high-latitude feedbacks over climate states that range from perennial or seasonal ice to ice-free conditions in the Arctic. © 2017 American Meteorological Society."
"55509658400;57192666611;57202824841;","Verification for Different Contrail Parameterizations Based on Integrated Satellite Observation and ECMWF Reanalysis Data",2017,"10.1155/2017/8707234","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031913746&doi=10.1155%2f2017%2f8707234&partnerID=40&md5=001d58bac2141ef488e0b4fad068ff6b","Aviation induced cloud termed contrail plays a more and more important role in the climate change, which makes a significant contribution to anthropogenic climate forcing through impacting the coverage of cirrus in the intersection of troposphere and stratosphere. In this paper, we propose one novel automatic contrail detecting method based on Himawari-8 stationary satellite imagery and two kinds of potential contrail coverage (PCC1 and PCC2) from contrail parameterization in ECHAM4 and HadGEM2. In addition, we propose one new climatological index called contrail occurrence and persistence (COP). According to the algorithm identification (AI) and artificial visual inspection (AVI), COP measured from Himawari-8 stationary satellite imagery is related to upper tropospheric relative humidity over ice (RHI) computed with the ECMWF reanalysis data by simple linear regression. Similarly, we compared the linear correlation between COP and PCCs fractions and found that PCC1 has better correspondence with COP than PCC2. © 2017 Jinglin Zhang et al."
"56263595100;57193212757;7410070663;57191035694;7005642066;","Variational iteration method for infrared radiative transfer in a scattering medium",2017,"10.1175/JAS-D-16-0172.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011649654&doi=10.1175%2fJAS-D-16-0172.1&partnerID=40&md5=9526c65d77a1d38033e23f2a3db43b6f","A new scheme is proposed for using the variational iteration method (VIM) to solve the problem of infrared radiative transfer in a scattering medium. This scheme allows the zeroth-order solution to be identified as the absorption approximation and the scattering effect is included in the first-order iteration. The upward and downward intensities are calculated separately in VIM, which simplifies the calculation process. By applying VIM to two single-layer scattering media and a full radiation algorithm with gaseous transmission, it is found that VIM is generally more accurate than the discrete-ordinates method (DOM), especially for cirrostratus. Computationally, VIM is slightly faster than DOM in the two-stream case but more than twice as fast in the four-stream case. In view of its high overall accuracy and computational efficiency, VIM is well suited to solving infrared radiative transfer in climate models. © 2017 American Meteorological Society."
"6701385171;57192963470;55268454800;55249801100;7102167757;","Regional responses to black carbon aerosols: The importance of air-sea interaction",2017,"10.1002/2017JD027589","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037983253&doi=10.1002%2f2017JD027589&partnerID=40&md5=797ce9cba792aa9ffcede65ee0a92153","The impact of modern black carbon aerosols on climate via their changes in radiative balance is studied using a coupled model where sea surface temperatures (SSTs) are allowed to vary and an atmosphere-only version of the same model where SSTs are held fixed. Allowing the ocean to respond is shown to have a profound impact on the pattern of temperature change. Particularly, large impacts are found in the North Pacific (which cools by up to 1 K in the coupled model) and in north central Asia (which warms in the coupled simulation and cools in the fixed SST simulation). Neither set of experiments shows large changes in surface temperatures in the Southeast Asian region where the atmospheric burden of black carbon is highest. These results are related to the stabilization of the atmosphere and changes in oceanic heat transport. Over the North Pacific, atmospheric stabilization results in an increase in stratiform clouds. The resulting shading reduces evaporation, freshening the surface layer of the ocean and reducing the inflow of warm subtropical waters. Over the land, a delicate balance between greater atmospheric absorption, shading of the surface and changes in latent cooling of the surface helps to determine whether warming or cooling is seen. Our results emphasize the importance of coupling in determining the response of the climate system to black carbon and suggest that black carbon may play an important role in modulating climate change over the North Pacific. © 2017. American Geophysical Union. All Rights Reserved."
"8412168800;56542190700;7005034568;7201858544;55493559100;6602760623;7404340979;6506823865;","A 1DVAR-based snowfall rate retrieval algorithm for passive microwave radiometers",2017,"10.1002/2016JD026325","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021400950&doi=10.1002%2f2016JD026325&partnerID=40&md5=256a51690ac894200479ef26621de2bc","Snowfall rate retrieval from spaceborne passive microwave (PMW) radiometers has gained momentum in recent years. PMW can be so utilized because of its ability to sense in-cloud precipitation. A physically based, overland snowfall rate (SFR) algorithm has been developed using measurements from the Advanced Microwave Sounding Unit-A/Microwave Humidity Sounder sensor pair and the Advanced Technology Microwave Sounder. Currently, these instruments are aboard five polar-orbiting satellites, namely, NOAA-18, NOAA-19, Metop-A, Metop-B, and Suomi-NPP. The SFR algorithm relies on a separate snowfall detection algorithm that is composed of a satellite-based statistical model and a set of numerical weather prediction model-based filters. There are four components in the SFR algorithm itself: cloud properties retrieval, computation of ice particle terminal velocity, ice water content adjustment, and the determination of snowfall rate. The retrieval of cloud properties is the foundation of the algorithm and is accomplished using a one-dimensional variational (1DVAR) model. An existing model is adopted to derive ice particle terminal velocity. Since no measurement of cloud ice distribution is available when SFR is retrieved in near real time, such distribution is implicitly assumed by deriving an empirical function that adjusts retrieved SFR toward radar snowfall estimates. Finally, SFR is determined numerically from a complex integral. The algorithm has been validated against both radar and ground observations of snowfall events from the contiguous United States with satisfactory results. Currently, the SFR product is operationally generated at the National Oceanic and Atmospheric Administration and can be obtained from that organization. © 2017. American Geophysical Union. All Rights Reserved."
"56046478800;7005821477;6603768446;8408994300;55663817800;39561656500;57193958103;","WRF nested large-eddy simulations of deep convection during SEAC4RS",2017,"10.1002/2016JD025465","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017648611&doi=10.1002%2f2016JD025465&partnerID=40&md5=a59a104560bf4721e240bd3e58b516cb","Large-eddy simulations (LES) and observations are often combined to increase our understanding and improve the simulation of deep convection. This study evaluates a nested LES method that uses the Weather Research and Forecasting (WRF) model and, specifically, tests whether the nested LES approach is useful for studying deep convection during a real-world case. The method was applied on 2 September 2013, a day of continental convection that occurred during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign. Mesoscale WRF output (1.35 km grid length) was used to drive a nested LES with 450m grid spacing, which then drove a 150m domain. Results reveal that the 450m nested LES reasonably simulates observed reflectivity distributions and aircraft-observed in-cloud vertical velocities during the study period. However, when examining convective updrafts, reducing the grid spacing to 150m worsened results. We find that the simulated updrafts in the 150m run become too diluted by entrainment, thereby generating updrafts that are weaker than observed. Lastly, the 450m simulation is combined with observations to study the processes forcing strong midlevel cloud/updraft edge downdrafts that were observed on 2 September. Results suggest that these strong downdrafts are forced by evaporative cooling due to mixing and by perturbation pressure forces acting to restore mass continuity around neighboring updrafts. We conclude that the WRF nested LES approach, with further development and evaluation, could potentially provide an effective method for studying deep convection in real-world cases. © 2017. American Geophysical Union. All Rights Reserved."
"57193623489;12144198300;57193627600;57201744640;57205397413;","Quantitative three-dimensional ice roughness from scanning electron microscopy",2017,"10.1002/2016JD026094","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015275176&doi=10.1002%2f2016JD026094&partnerID=40&md5=c62b793b0fcbcd11d02b32d2b0e7d5ac","We present a method for inferring surface morphology of ice from scanning electron microscope images. We first develop a novel functional form for the backscattered electron intensity as a function of ice facet orientation; this form is parameterized using smooth ice facets of known orientation. Three-dimensional representations of rough surfaces are retrieved at approximately micrometer resolution using Gauss-Newton inversion within a Bayesian framework. Statistical analysis of the resulting data sets permits characterization of ice surface roughness with a much higher statistical confidence than previously possible. A survey of results in the range -39°C to -29°C shows that characteristics of the roughness (e.g., Weibull parameters) are sensitive not only to the degree of roughening but also to the symmetry of the roughening. These results suggest that roughening characteristics obtained by remote sensing and in situ measurements of atmospheric ice clouds can potentially provide more facet-specific information than has previously been appreciated. The authors have found a way to extract three-dimensional information about the surfaces of tiny ice crystals grown under a high-powered scanning electron microscope. They found that these surfaces contain some unexpected features, with long, deep valleys in some instances, and rounded hills in others. The authors believe that these features may help understand how rough ice surfaces in real cirrus clouds affect Earth’s climate. © 2017. American Geophysical Union. All Rights Reserved."
"7102833569;56246783000;35253736000;20434970400;6603156896;","Possible role of aerosols in the charge structure of isolated thunderstorms",2017,"10.1016/j.atmosres.2016.09.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988892832&doi=10.1016%2fj.atmosres.2016.09.016&partnerID=40&md5=aec98da0fe0d61e2c12691932b77cd90","The electric field and Maxwell current density measured below 32 small isolated thunderstorms over Pune (India) have been analyzed here. These data clearly show the presence of 10 out of 32 thunderstorms with inverted polarity charge structure. Values of Aerosol Optical Depth (AOD) on thunderstorm days taken from MODIS show that all the thunderstorms with inverted polarity occurred on days with significantly higher AOD compared to normal polarity thunderstorms. The peak flash rate did not show significant difference between normal polarity thunderstorms and inverted polarity thunderstorms. The dew point depression (DPD) during pre-monsoon thunderstorms shows good correlation with inverted polarity charge structure. Observations suggest that aerosol concentration plays an important role in the formation of inverted polarity charge structure in these thunderclouds. In presence of high aerosol concentration with adequate ice nuclei non-inductive charging mechanism can produce strong and wide spread positive charge region in the lower portion of cloud. However, observed good correlation of DPD with inverted polarity charge structure in the pre-monsoon period suggest that the effect of high cloud base height on inverted polarity charge structure as suggested by Williams et al. (2005) cannot be ruled out. © 2016"
"56300178700;55495868700;56278774300;50462946300;57062525000;56278523400;","3D aerosol climatology over East Asia derived from CALIOP observations",2017,"10.1016/j.atmosenv.2017.01.013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008941099&doi=10.1016%2fj.atmosenv.2017.01.013&partnerID=40&md5=0409504d29134df88d11ec3874d1fccc","The seasonal mean extinction coefficient profile (ECP), single scattering albedo (SSA), and scattering phase function (SPF) derived from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) version 3 Level 2 5-km aerosol profile product (2011–2014) were compiled into a three-dimensional (3D) aerosol climatology for East Asia. The SSA and SPF were calculated as the weighted averages of the scattering properties of the CALIOP aerosol subtypes. The weights were set to the occurrence frequencies of the subtypes. The single scattering properties of each subtype were extrapolated from the volume-based size distribution and complex refractive indexes based on Mie calculations. For the high-loading episodes (aerosol optical depth ≥ 0.6), the exponential ECP structures were most frequently observed over the farmland and desert areas, along with the uplifted ECP structures over the marine and coastal areas. Besides the desert areas, high-loading episodes also occurred over areas with frequent agricultural and industry activities. Unlike the conventional half-3D aerosol climatology (vertically constant SSA and SPF), this newly generated climatology specified SSA and SPF in the full-3D space (full-3D aerosol climatology). Errors on the shortwave radiative heating rate (SW RHR) due to the half-3D aerosol climatology approximation were quantified. The SW RHR errors were around ±1 K/day, implying that the half-3D aerosol climatology should be used with caution in climate modeling. This study is among the first to generate a full-3D aerosol climatology from the CALIOP data. This full-3D aerosol climatology is potentially useful for aerosol remote sensing and climate modeling. © 2017 Elsevier Ltd"
"55352969400;37026579600;6701477373;7003554893;7004461962;24329221600;7102425008;56000366900;7102128820;23768540500;","Towards process-level representation of model uncertainties: stochastically perturbed parametrizations in the ECMWF ensemble",2017,"10.1002/qj.2931","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006365229&doi=10.1002%2fqj.2931&partnerID=40&md5=1e5aaf743d72ee2036689e1cb261b1d1","Ensemble forecasts depend on representations of model uncertainties. Here, we introduce a model uncertainty representation where a novel approach is taken to the established methodology of perturbing model parameters. The Stochastically Perturbed Parametrizations (SPP) scheme applies spatially and temporally varying perturbations to 20 parameters and variables in the ECMWF IFS model. The perturbed quantities are chosen from the IFS parametrizations of (a) turbulent diffusion and subgrid orography, (b) convection, (c) clouds and large-scale precipitation, and (d) radiation. The perturbations are drawn from prescribed distributions. Numerous configurations of SPP are compared in experiments with the ECMWF ensemble forecasts at TL399 resolution up to 15 day lead times. Halving the standard deviations of the perturbations considerably reduces the ensemble spread. Smaller variations of the standard deviations lead to minor changes to the ensemble spread. Experiments with different space and time correlations for the perturbations suggest optimal correlation scales of 2000 km and 72 h. SPP displays a lower skill for upper-air variables in the medium range than the current operational model uncertainty scheme Stochastically Perturbed Parametrization Tendencies (SPPT) for a given set of fixed initial-state perturbations. However, in short ranges the two schemes display similar skill. Moreover, verification against surface observations shows SPP is more skilful than SPPT in 2 m temperature for the first couple of forecast days. We show that the direct perturbation of cloud (and radiation) processes in SPP has a greater impact on radiative fluxes than the indirect perturbation via SPPT. SPP also produces a better model climate for a range of variables when comparing long model integrations with the two schemes, indicating the potential advantage of a physically consistent model uncertainty representation. A comparison of the tendency perturbations introduced by SPP and SPPT suggests that the two schemes represent different aspects of model uncertainty. © 2016 Royal Meteorological Society"
"57104690900;35209683700;7406523040;7408519295;","A process-based assessment of decadal-scale surface temperature evolutions in the NCAR CCSM4's 25-year hindcast experiments",2017,"10.1175/JCLI-D-16-0869.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027262514&doi=10.1175%2fJCLI-D-16-0869.1&partnerID=40&md5=0b520a049f437eaf7e4bb53e9b90595f","This study represents an initial effort in the context of the coupled atmosphere-surface climate feedback-response analysis method (CFRAM) to partition the temporal evolution of the global surface temperature from 1981 to 2005 into components associated with individual radiative and nonradiative (dynamical) processes in the NCAR CCSM4's decadal hindcasts. When compared with the observation (ERA-Interim), CCSM4 is able to predict an overall warming trend as well as the transient cooling occurring during the period 1989-94. However, while the model captures fairly well the positive contributions of the CO2 and surface albedo change to the temperature evolution, it has an overly strong water vapor effect that dictates the temperature evolution in the hindcast. This is in contrast with ERA-Interim, where changes in surface dynamics (mainly ocean circulation and heat content change) dominate the actual temperature evolution. Atmospheric dynamics in both ERA-Interim and the model work against the surface temperature tendency through turbulent and convective heat transport, leading to an overall negative contribution to the evolution of the surface temperature. Impacts of solar forcing and ozone change on the surface temperature change are relatively weak during this period. The magnitude of cloud effect is considerably smaller compared to that in ERA-Interim and the spatial distribution of the cloud effect is also significantly different between the two, especially over the equatorial Pacific. The value and limitations of this process-based temperature decomposition are discussed. © 2017 American Meteorological Society."
"35223590200;23486734100;7006306835;56744278700;","Changes of the tropical tropopause layer under global warming",2017,"10.1175/JCLI-D-16-0457.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012284288&doi=10.1175%2fJCLI-D-16-0457.1&partnerID=40&md5=625c4bc3cc6bdfb5f034c38ee469ab9a","This paper investigates changes in the tropical tropopause layer (TTL) in response to carbon dioxide increase and surface warming separately in an atmospheric general circulation model, finding that both effects lead to a warmer tropical tropopause. Surface warming also results in an upward shift of the tropopause. A detailed heat budget analysis is performed to quantify the contributions from different radiative and dynamic processes to changes in the TTL temperature. When carbon dioxide increases with fixed surface temperature, a warmer TTL mainly results from the direct radiative effect of carbon dioxide increase. With surface warming, the largest contribution to the TTL warming comes from the radiative effect of the warmer troposphere, which is partly canceled by the radiative effect of the moistening at the TTL. Strengthening of the stratospheric circulation following surface warming cools the lower stratosphere dynamically and radiatively via changes in ozone. These two effects are of comparable magnitudes. This circulation change is the main cause of temperature changes near 63 hPa but is weak near 100 hPa. Contributions from changes in convection and clouds are also quantified. These results illustrate the heat budget analysis as a useful tool to disentangle the radiative-dynamical-chemical-convective coupling at the TTL and to facilitate an understanding of intermodel difference. © 2017 American Meteorological Society."
"36538539800;56942554300;56612517400;","Multi-year application of WRF-CAM5 over East Asia-Part II: Interannual variability, trend analysis, and aerosol indirect effects",2017,"10.1016/j.atmosenv.2017.06.029","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021738137&doi=10.1016%2fj.atmosenv.2017.06.029&partnerID=40&md5=291a6f8237b483efbf6f0e417ac8eb53","Following a comprehensive evaluation of WRF-CAM5 in Part I, Part II describes analyses of interannual variability, multi-year variation trends, and the direct, indirect, and total effects of anthropogenic aerosols. The interannual variations of chemical column and surface concentrations, and ozone (O3)/particulate matter (PM) indicators are strongly correlated to anthropogenic emission changes. Despite model biases, the model captures well the observed interannual variations of temperature at 2-m, cloud fraction, shortwave cloud forcing, downwelling shortwave radiation, cloud droplet number concentration, column O3, and column formaldehyde (HCHO) for the whole domain. While the model reproduces the volatile organic compound (VOC)-limited regimes of O3 chemistry at sites in Hong Kong, Taiwan, Japan, South Korea, and from the Acid Deposition Monitoring Network in East Asia (EANET) and the degree of sulfate neutralization at the EANET sites, it has limited capability in capturing the interannual variations of the ratio of O3 and nitrogen dioxide (O3/NO2) and PM chemical regime indicators, due to uncertainties in the emissions of precursors for O3 and secondary PM, the model assumption for ammonium bisulfate (NH4HSO4) as well as lack of gas/particle partitioning of total ammonia and total nitrate. While the variation trends in multi-year periods in aerosol optical depth and column concentrations of carbon monoxide, sulfur dioxide, and NO2 are mainly caused by anthropogenic emissions, those of major meteorological and cloud variables partly reflect feedbacks of chemistry to meteorological variables. The impacts of anthropogenic aerosol indirect effects either dominate or play an important role in the aerosol total effects for most cloud and chemical predictions, whereas anthropogenic aerosol direct effects influence most meteorological and radiation variables. The direct, indirect, and total effects of anthropogenic aerosols exhibit a strong interannual variability in 2001, 2006, and 2011. © 2017 Elsevier Ltd"
"36149540700;7202155374;","On the spatial gradient of soil moisture-precipitation feedback strength in the April 2011 drought in the southern Great Plains",2017,"10.1175/JCLI-D-13-00185.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010843529&doi=10.1175%2fJCLI-D-13-00185.1&partnerID=40&md5=bf868bbebefa1188f432f1d94dc3499e","The southern Great Plains (SGP) experienced a record-breaking drought in 2011, in which the excessively dry conditions established quickly in spring (i.e., April) and extended into summer. A regional climate model is used (after its evaluation) to simulate this April drought and investigate how a soil moisture anomaly could affect the development of its precipitation deficit. The authors examine how the local thermodynamic structure of the overlying atmosphere contributes to soil moisture feedbacks and how these feedbacks are connected to nonlocal mechanisms. The simulations establish a zonal gradient in the (generally positive) feedback strength [i.e., a significant (negligible) precipitation increase over the eastern (western) SGP] under an SGP-wide wet soil moisture anomaly and spatially similar evapotranspiration (ET) increments. This pattern is dominated by convective precipitation and consistent with spatial gradients in parameters relevant to moist convection, including the precipitable water, the low-level instability and humidity, and the local cloud water content. All these variables are sensitive to a wet soil moisture anomaly, but precipitation responds differently to their changes in different locations. Furthermore, the impacts of the soil moisture anomaly on various large-scale atmospheric fields are related to the spatial structure of feedback strength. Additionally, the weaker feedback over the western SGP occurs in a region of relatively strong subsidence and changes little with a westward expansion of the anomaly area, whereas nonlocal soil moisture impacts-in particular, moisture advection from the west-are important for the stronger feedback over the eastern SGP."
"55806597500;7007020349;7401513851;7102947372;","Numerical simulation of urban land surface effects on summer convective rainfall under different UHI intensity in Beijing",2017,"10.1002/2017JD026614","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026788353&doi=10.1002%2f2017JD026614&partnerID=40&md5=22137006f062f5e86b27881457fa5e86","To investigate the effect of urban land surface on rainfall under different urban heat island intensity (UHII) conditions in Beijing, numerical simulation and sensitivity experiments on two individual summer convective rainfall events are performed, using the Weather Research and Forecasting/Noah/urban canopy model (UCM) model system. It is found that the cloud ice and cloud graupel formation processes in the microphysics parameterization scheme play a pivotal role in increasing the model’s ability to simulate convective rainfall. When UHI is weak prior to the start of rainfall, urban land surface primarily affects rainfall through its dynamic action. Rainfall systems develop a tendency to bifurcate in the windward periphery of the urban area and move around it along both sides. Consequently, precipitation in the central urban area and its downstream area decreases, whereas precipitation in the suburban areas at the sides of the periphery of the urban area increases. When UHI is strong before rainfall begins, the thermal effect of the urban land surface is the main factor that affects rainfall. The lower atmosphere over urban area is more unstable, and horizontal convergence is enhanced, increasing the intensity of the convective system after it moves to the urban area. As a result, precipitation increases in the urban area. This study demonstrates that UHII can be used as an important factor for distinguishing the effect of urban land surface on rainfall. © 2017. American Geophysical Union. All Rights Reserved."
"57190697430;","A statistical comparison of cirrus particle size distributions measured using the 2-D stereo probe during the TC4, SPARTICUS, and MACPEX flight campaigns with historical cirrus datasets",2017,"10.5194/amt-10-3041-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044032095&doi=10.5194%2famt-10-3041-2017&partnerID=40&md5=cec19c91c3f7d8ee23167c4cf03b2407","This paper addresses two straightforward questions. First, how similar are the statistics of cirrus particle size distribution (PSD) datasets collected using the Two- Dimensional Stereo (2D-S) probe to cirrus PSD datasets collected using older Particle Measuring Systems (PMS) 2-D Cloud (2DC) and 2-D Precipitation (2DP) probes? Second, how similar are the datasets when shatter-correcting postprocessing is applied to the 2DC datasets? To answer these questions, a database of measured and parameterized cirrus PSDs - constructed from measurements taken during the Small Particles in Cirrus (SPARTICUS); Mid-latitude Airborne Cirrus Properties Experiment (MACPEX); and Tropical Composition, Cloud, and Climate Coupling (TC4) flight campaigns - is used. Bulk cloud quantities are computed from the 2D-S database in three ways: first, directly from the 2D-S data; second, by applying the 2D-S data to ice PSD parameterizations developed using sets of cirrus measurements collected using the older PMS probes; and third, by applying the 2D-S data to a similar parameterization developed using the 2D-S data themselves. This is done so that measurements of the same cloud volumes by parameterized versions of the 2DC and 2D-S can be compared with one another. It is thereby seen - given the same cloud field and given the same assumptions concerning ice crystal cross-sectional area, density, and radar cross section - that the parameterized 2D-S and the parameterized 2DC predict similar distributions of inferred shortwave extinction coefficient, ice water content, and 94 GHz radar reflectivity. However, the parameterization of the 2DC based on uncorrected data predicts a statistically significantly higher number of total ice crystals and a larger ratio of small ice crystals to large ice crystals than does the parameterized 2D-S. The 2DC parameterization based on shatter-corrected data also predicts statistically different numbers of ice crystals than does the parameterized 2D-S, but the comparison between the two is nevertheless more favorable. It is concluded that the older datasets continue to be useful for scientific purposes, with certain caveats, and that continuing field investigations of cirrus with more modern probes is desirable. © 2017 Author(s)."
"56663169300;6701820813;6602922582;","Atmospheric, radiative, and hydrologic effects of future land use and land cover changes: A global and multimodel climate picture",2017,"10.1002/2016JD025448","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020748482&doi=10.1002%2f2016JD025448&partnerID=40&md5=d7e18ba83d6f6ec05de8e669cc408274","Land use and land cover changes (LULCC) modulate land surface energy, heat, moisture, and momentum fluxes. Using simulations performed with and without LULCC for five earth system models, averaged over the 2071-2100 period, we quantify the biophysical effects in response to a future realistic LULCC scenario (Representative Concentration Pathway RCP8.5) on 15 climate variables (i.e., atmospheric, radiative, wind, hydrologic variables, and heat fluxes). We find that climate models are able to simulate some robust and strong climate perturbations in response to LULCC. In tropical regions with substantial LULCC, significantly higher skin temperatures, less precipitation and soil moisture, less evaporation and clouds, more incoming radiation and stronger winds, more anticyclonic conditions and subsidence, are simulated in response to future LULCC. In midlatitude and high latitude, LULCC result in autumn cooling and higher tropospheric pressures, while East Asia is drier, warmer, with higher sensible heat flux and lower evaporation. The tropical wind strengthening and weakening of the hydrological cycle are comparable in magnitude to their future regional changes induced by greenhouse gases under RCP8.5, which make LULCC an indispensable forcing to take into account in future climatic assessments. Finally, our study reveals significant indirect atmospheric processes triggered by LULCC, implying substantial changes in incoming radiation, which dominate climatic responses over the direct effects, particularly in boreal regions. Plain Language Summary Trees affect climate not only by modulating greenhouse gases sequestration but also by regulating the exchange of energy, heat, water, and momentum with the atmosphere. However, few studies quantified, in a consistent way, all the latter perturbations for a realistic deforestation scenario or with several models. Analyzing five earth system models, for a common future business-as-usual land use and land cover changes (LULCC) scenario, we show that significant atmospheric, radiative, and hydrologic changes are robustly simulated. Among others, the weakened hydrological cycle and the wind strengthening due to tropical deforestation are comparable in magnitude to the projected changes induced by greenhouse gases. Our investigation also reveals significant indirect atmospheric processes triggered by LULCC, implying substantial changes in incoming radiation, which dominate climatic responses over the direct effects (albedo, evapotranspiration, or roughness changes), particularly in boreal regions. In consequence, LULCC are a critical forcing that needs to be taken into account for future climatic assessments. © 2017. American Geophysical Union. All Rights Reserved."
"57194450165;","Big data's big handprint",2017,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020197598&partnerID=40&md5=e7f9ab708a665802053b9ecea79828d3","The collection and processing of information will yield huge environmental improvements in other sectors. The growth of big data is driven by the expansion of computing generally and the growth of the Internet of Things in particular. Perhaps the biggest contribution to environmental improvement that big data and ICT actions can deliver is in the realm of climate change. ICT companies like Intel are now providing building management platforms that allow owners of small- and medium-sized structures to access management services that they could not afford. These platforms connect to disparate equipment and devices, sending their data to the cloud for a variety of analytical functions concerning energy use and maintenance needs. Big data and ICT can also help society adapt to the climate change that already is evident. Companies and communities can be directly and indirectly impacted by such changes and have a need to be able to monitor, forecast, and adapt to developments. Experts in the field of climate adaptation have identified a number of ways big data can play a useful role. The use of satellite and aerial land use imagery is key to this function. Big data, particularly generated via remote sensing, is increasingly used in managing water resources. Big data sets can cover water quality and quantity as well as demand. This knowledge can be valuable to land trusts and local planners in designing conservation easements, agricultural best practices, and nutrient trading programs."
"56149492300;56942554300;56003666300;57213551855;55462884000;56612517400;55884921500;36538539800;","Decadal application of WRF/Chem for regional air quality and climate modeling over the U.S. under the representative concentration pathways scenarios. Part 1: Model evaluation and impact of downscaling",2017,"10.1016/j.atmosenv.2016.12.029","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009092338&doi=10.1016%2fj.atmosenv.2016.12.029&partnerID=40&md5=493a2b063d2c6e5cd5518688398efdaa","An advanced online-coupled meteorology-chemistry model, i.e., the Weather Research and Forecasting Model with Chemistry (WRF/Chem), is applied for current (2001–2010) and future (2046–2055) decades under the representative concentration pathways (RCP) 4.5 and 8.5 scenarios to examine changes in future climate, air quality, and their interactions. In this Part I paper, a comprehensive model evaluation is carried out for current decade to assess the performance of WRF/Chem and WRF under both scenarios and the benefits of downscaling the North Carolina State University's (NCSU) version of the Community Earth System Model (CESM_NCSU) using WRF/Chem. The evaluation of WRF/Chem shows an overall good performance for most meteorological and chemical variables on a decadal scale. Temperature at 2-m is overpredicted by WRF (by ∼0.2–0.3 °C) but underpredicted by WRF/Chem (by ∼0.3–0.4 °C), due to higher radiation from WRF. Both WRF and WRF/Chem show large overpredictions for precipitation, indicating limitations in their microphysics or convective parameterizations. WRF/Chem with prognostic chemical concentrations, however, performs much better than WRF with prescribed chemical concentrations for radiation variables, illustrating the benefit of predicting gases and aerosols and representing their feedbacks into meteorology in WRF/Chem. WRF/Chem performs much better than CESM_NCSU for most surface meteorological variables and O3hourly mixing ratios. In addition, WRF/Chem better captures observed temporal and spatial variations than CESM_NCSU. CESM_NCSU performance for radiation variables is comparable to or better than WRF/Chem performance because of the model tuning in CESM_NCSU that is routinely made in global models. © 2016 Elsevier Ltd"
"7403324762;57194623907;57193857181;","Comparison of the Long-Range Climate Memory in Outgoing Longwave Radiation over the Tibetan Plateau and the Indian Monsoon Region",2017,"10.1155/2017/7637351","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85031911329&doi=10.1155%2f2017%2f7637351&partnerID=40&md5=501d647e7874ba08524739f0593e7f2f","Based on the detrended fluctuation analysis (DFA) method, scaling behaviors of the daily outgoing longwave radiation (OLR) from 1979 to 2015 over the Tibetan Plateau (TP) and the Indian Monsoon Region (IMR) are analyzed. The results show that there is long-Term memory for the OLR time series over the TP and IMR. The long-range memory behaviors of OLR over TP are stronger than those over IMR. The averaged values of the scaling exponents over TP and IMR are 0.71 and 0.64; the maximum values in the two regions are 0.81 and 0.75; the minimum values are 0.59 and 0.58. The maximum frequency counts for scaling exponents occur in the range of 0.625 and 0.675 both in TP and in IMR. The spatial distribution of the scaling exponents of the OLR sequence is closely related to the conditions of climatic high cloud cover in the two areas. The high cloud cover over TP is obviously less than that of IMR. In addition, the scaling behaviors of OLR over TP and IMR are caused by the fractal characteristics of time series, which is further proved by randomly disrupting the time series to remove trends and correlation. © 2017 Zhongping Shen et al."
"16425609300;8856938500;7101874266;7404062063;","Observations and fine-scalemodel simulations of gravity waves over Davis, East Antarctica (69°S, 78°E)",2017,"10.1002/2017JD026615","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027679722&doi=10.1002%2f2017JD026615&partnerID=40&md5=39a0a6fc3ad8fdc1e2d367ac22389992","Large vertical velocities were observed throughout the troposphere at Davis, East Antarctica, on 18 February 2014 by a VHF wind-profiling radar. Simulations using the Met Office Unified Model at 2.2, 0.5, and 0.1 km horizontal grid spacing were able to broadly capture the location, timing, and magnitude of the observed velocities, as well as reveal that they are due to small-scale orographic gravity waves resulting from the interaction between the coastal topography and strong easterly winds associated with a synoptic-scale cyclone situated to the north. The simulations indicated that the gravity waves are responsible for (i) temperature fluctuations which coincided with satellite-observed cloud variations in the vicinity of Davis, suggesting that they have a crucial role in the formation of cirrus clouds, and (ii) large vertical momentum fluxes in the troposphere. The waves are prevented from propagating into the stratosphere by the background winds turning from near-surface easterlies to lower stratospheric northerlies. As well as illuminating and quantifying the role that weather systems have in producing orographic gravity waves along the East Antarctic coastline, studies such as this should be exploited to improve the representation of key localized atmospheric processes in global climate models. © 2017. American Geophysical Union."
"56381667700;53871813100;6603342397;","Circulation conditions' effect on the occurrence of heatwaves in Western and Southwestern Europe",2017,"10.3390/atmos8020031","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013418916&doi=10.3390%2fatmos8020031&partnerID=40&md5=f5a58f84171c00ebfcf92e1caa0251ff","This article aims to describe the occurrence of heat waves in Western and Southwestern Europe in the period 1976-2015 and determining pressure patterns that cause a persistence of hot days. A hot day was defined as a day on which the daily maximum air temperature was higher than the 95th annual percentile; and a heat wave was recognised as a sequence of at least five days of the abovementioned category. In the discussed multiannual period, this threshold ranged from 23.5 °C in Brest to 38.9 °C in Seville. Within the analysed area, there were from 14 (Bilbao) to 54 (Montélimar) heat waves observed. The longest heat wave took place in 2003 in Nice and lasted 49 days (14 July-31 August). The occurrence of heat waves within the analysed area was related to the ridge of high pressure located over the area of the study, providing strong solar radiation flux due to cloudlessness or a small cloud cover. Positive SLP, z500 hPa and T850 anomalies occurred over the majority of the research area. © 2017 by the author."
"55249801100;6701385171;7102167757;55268454800;","Transient response of the Southern Ocean to changing ozone: Regional responses and physical mechanisms",2017,"10.1175/JCLI-D-16-0474.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015856267&doi=10.1175%2fJCLI-D-16-0474.1&partnerID=40&md5=86de0f8e48fae574c032ce0069fef1e4","The impact of changing ozone on the climate of the Southern Ocean is evaluated using an ensemble of coupled climate model simulations. By imposing a step change from 1860 to 2000 conditions, response functions associated with this change are estimated. The physical processes that drive this response are different across time periods and locations, as is the sign of the response itself. Initial cooling in the Pacific sector is driven not only by the increased winds pushing cold water northward, but also by the southward shift of storms associated with the jet stream. This shift drives both an increase in cloudiness (resulting in less absorption of solar radiation) and an increase in net freshwater flux to the ocean (resulting in a decrease in surface salinity that cuts off mixing of warm water from below). A subsurface increase in temperature associated with this reduction in mixing then upwells along the Antarctic coast, producing a subsequent warming. Similar changes in convective activity occur in the Weddell Sea but are offset in time. Changes in sea ice concentration also play a role in modulating solar heating of the ocean near the continent. The time scale for the initial cooling is much longer than that seen in NCAR CCSM3.5, possibly reflecting differences in natural convective variability between that model (which has essentially no Southern Ocean deep convection) and the one used here (which has a large and possibly unrealistically regular mode of convection) or to differences in cloud feedbacks or in the location of the anomalous winds. © 2017 American Meteorological Society."
"57164106400;7408519295;","Feedback attributions to the dominant modes of East Asian winter monsoon variations",2017,"10.1175/JCLI-D-16-0275.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010902409&doi=10.1175%2fJCLI-D-16-0275.1&partnerID=40&md5=634e630f6f75528a197861e3ad85de5b","This study investigates the variations and feedback attributions of changes in surface temperature between strong and weak East Asian winter monsoons. The variations of winter-mean surface air temperature are dominated by two distinct principal modes that account for 70.9% of the total variance. The first mode features high correlation with the high-latitude atmospheric circulation, including a correlation coefficient of -0.53 with the Arctic Oscillation in January, and the second mode is significantly linked to El Niño-Southern Oscillation, with a correlation coefficient of -0.37. The surface temperature anomalies of each mode are decomposed into partial temperature anomalies resulting from radiative and nonradiative feedback processes by applying a coupled climate feedback-response analysis method to quantify contributions from thermodynamic and dynamic processes. Results indicate that the surface cooling associated with both modes is mainly attributed to the nonradiative feedback processes of atmospheric dynamics and surface sensible heating and to the radiative feedback processes of water vapor and clouds. The first mode exhibits a deep barotropic anomalous high that weakens the high-latitude westerly jet stream but strengthens the midlatitude westerly jet stream. This circulation feature traps cold and dry air over northern East Asia. For the second mode, the ocean and land heat storage processes induce a large thermal gradient over eastern China and the northwestern Pacific, resulting in a large pressure gradient. Northerly anomalies further reinforce the pressure gradient, which favors cold air intruding southward into the tropics."
"7201488063;12761052200;55893823700;35096299800;6701588531;57193792801;6701357023;7102976560;6507575165;49261186800;25031430500;36876405100;6701431208;6701511321;","Radiative and chemical response to interactive stratospheric sulfate aerosols in fully coupled CESM1(WACCM)",2017,"10.1002/2017JD027006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051835589&doi=10.1002%2f2017JD027006&partnerID=40&md5=061b2d4047703e3142cd5a5e6d1ffe2b","We present new insights into the evolution and interactions of stratospheric aerosol using an updated version of the Whole Atmosphere Community Climate Model (WACCM). Improved horizontal resolution, dynamics, and chemistry now produce an internally generated quasi-biennial oscillation and significant improvements to stratospheric temperatures and ozone compared to observations. We present a validation of WACCM column ozone and climate calculations against observations. The prognostic treatment of stratospheric sulfate aerosols accurately represents the evolution of stratospheric aerosol optical depth and perturbations to solar and longwave radiation following the June 1991 eruption of Mount Pinatubo. We confirm the inclusion of interactive OH chemistry as an important factor in the formation and initial distribution of aerosol following large inputs of sulfur dioxide (SO2) to the stratosphere. We calculate that depletion of OH levels within the dense SO2 cloud in the first weeks following the Pinatubo eruption significantly prolonged the average initial e-folding decay time for SO2 oxidation to 47 days. Previous observational and model studies showing a 30 day decay time have not accounted for the large (30–55%) losses of SO2 on ash and ice within 7–9 days posteruption and have not correctly accounted for OH depletion. We examine the variability of aerosol evolution in free-running climate simulations due to meteorology, with comparison to simulations nudged with specified dynamics. We assess calculated impacts of volcanic aerosols on ozone loss with comparisons to observations. The completeness of the chemistry, dynamics, and aerosol microphysics in WACCM qualify it for studies of stratospheric sulfate aerosol geoengineering. © 2017. American Geophysical Union. All Rights Reserved."
"57197745085;7005602760;13406365400;","The properties of mesoscale convective systems in Indonesia detected using the grab ‘em tag ‘em graph ‘em (GTG) algorithm",2017,"10.2151/jmsj.2017-026","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034443513&doi=10.2151%2fjmsj.2017-026&partnerID=40&md5=9b9fd97f784656dca138794083ea7775","A mesoscale convective system (MCS) is organized thunderstorms with connected anvils, which has a significant impact on the global climate. By focusing on MCSs over the Maritime Continent of Indonesia, this study aims to gain a better understanding on the properties of the MCSs over the study area. The “Grab ‘em Tag ‘em Graph ‘em” (GTG) tracking algorithm is applied to hourly Multi-functional Transport Satellite-1R data for two years to observe the distribution of MCSs and the evolution of MCSs along their lifetime. The results of MCS identification by using GTG are combined with CloudSat data products to study the vertical structure of the MCSs at various MCS life stages: developing, mature, and dissipating. The distribution of MCSs over Indonesia has a seasonal variation and distinct diurnal cycle. The life stages of the observed MCSs are characterized by distinct cloud microphysics at each stage. In the developing stage, the upper level of the MCS raining region shows the presence of precipitating ice particles. As the MCS progresses to the mature stage, the proportion of the raining area becomes small and the intensity of rain is reduced, accompanied by increasing occurrence of small-sized ice particles at the upper level. In the dissipating stage, large hydrometeors no longer exist at the upper part of the raining region. Within the MCS anvils, the dissipating stage shows a more uniform distribution of ice-particle effective radius compared to that shown by the developing and mature stages. MCS characteristics over the land and ocean differ on the basis of the minimum brightness temperature, the equivalent radius, the maximum rain rate, and the rain fraction that varies along the MCS evolution. © 2017, Meteorological Society of Japan."
"6602515941;22236015300;56690386600;","Quantifying the effect of riming on snowfall using ground-based observations",2017,"10.1002/2016JD026272","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017620827&doi=10.1002%2f2016JD026272&partnerID=40&md5=51dd30e52c4a316080d2e0a6706f7110","Ground-based observations of ice particle size distribution and ensemble mean density are used to quantify the effect of riming on snowfall. The rime mass fraction is derived from these measurements by following the approach that is used in a single ice-phase category microphysical scheme proposed for the use in numerical weather prediction models. One of the characteristics of the proposed scheme is that the prefactor of a power law relation that links mass and size of ice particles is determined by the rime mass fraction, while the exponent does not change. To derive the rime mass fraction, a mass-dimensional relation representative of unrimed snow is also determined. To check the validity of the proposed retrieval method, the derived rime mass fraction is converted to the effective liquid water path that is compared to microwave radiometer observations. Since dual-polarization radar observations are often used to detect riming, the impact of riming on dual-polarization radar variables is studied for differential reflectivity measurements. It is shown that the relation between rime mass fraction and differential reflectivity is ambiguous, other factors such as change in median volume diameter need also be considered. Given the current interest on sensitivity of precipitation to aerosol pollution, which could inhibit riming, the importance of riming for surface snow accumulation is investigated. It is found that riming is responsible for 5% to 40% of snowfall mass. The study is based on data collected at the University of Helsinki field station in Hyytiälä during U.S. Department of Energy Biogenic Aerosols Effects on Clouds and Climate (BAECC) field campaign and the winter 2014/2015. In total 22 winter storms were analyzed, and detailed analysis of two events is presented to illustrate the study. © 2017. American Geophysical Union. All Rights Reserved."
"35195849700;16448076700;57004751900;57197899812;","Multi-angle, dual wavelength scattering measurement chamber for the structural measurement of combustion generated particles",2017,"10.1016/j.jaerosci.2016.10.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994339706&doi=10.1016%2fj.jaerosci.2016.10.007&partnerID=40&md5=fac0fbae3abd4e7343ba7d9c5659036a","Soot particles are formed through combustion processes and have fractal-like shapes. They influence our climate by absorption and scattering of the solar radiation directly, and indirectly by their influence on cloud (liquid or glaciated) formation and their deposition on snow and ice surfaces. An Instrument, which we would like to introduce in this paper was developed and built at the University of Applied Sciences Northwestern Switzerland to measure light scattering properties of combustion type aerosols. A closed chamber was designed where the scattered light can be detected at 7 fixed, predefined angles simultaneously. Two lasers at 405 nm and 852 nm serve as light sources, and with that almost simultaneous measurements at the two different wavelengths can be carried out. The instrument is calibrated with aerosol particles of known scattering properties and concentration. We used nebulized, size selected ammonium sulphate particles for this purpose. The angular light scattering is influenced by the shape of the particles. In the case of fractals information on the fractal dimension and characteristic size can be derived from the angle dependence of the scattered light. In this paper we demonstrate and test the performance of this new light scattering instrument through the measurement of different soot or soot–containing aerosols. These examples include the measurement of artificial soot particles generated by two different soot generators (Cast soot and Palas soot generators) and different kind of combustion produced aerosols like: flaming ethanol, smouldering wood and mixed smouldering/flaming wood smokes. © 2016 Elsevier Ltd"
"25922028600;23388133600;57058730000;6507938636;","Understanding and applying principles of social cognition and decision making in adaptive environmental governance",2017,"10.5751/ES-09154-220133","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016752062&doi=10.5751%2fES-09154-220133&partnerID=40&md5=d1e31860c3eebd8893e12cb3feac03a9","Environmental governance systems are under greater pressure to adapt and to cope with increased social and ecological uncertainty from stressors like climate change. We review principles of social cognition and decision making that shape and constrain how environmental governance systems adapt. We focus primarily on the interplay between key decision makers in society and legal systems. We argue that adaptive governance must overcome three cooperative dilemmas to facilitate adaptation: (1) encouraging collaborative problem solving, (2) garnering social acceptance and commitment, and (3) cultivating a culture of trust and tolerance for change and uncertainty. However, to do so governance systems must cope with biases in people’s decision making that cloud their judgment and create conflict. These systems must also satisfy people’s fundamental needs for self-determination, fairness, and security, ensuring that changes to environmental governance are perceived as legitimate, trustworthy, and acceptable. We discuss the implications of these principles for common governance solutions (e.g., public participation, enforcement) and conclude with methodological recommendations. We outline how scholars can investigate the social cognitive principles involved in cases of adaptive governance. © 2017 by the author(s)."
"22982141200;55731174900;57210143001;57193438910;57190674605;57203321797;","Revisiting the relationship between observed warming and surface pressure in the tibetan plateau",2017,"10.1175/JCLI-D-15-0834.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014007674&doi=10.1175%2fJCLI-D-15-0834.1&partnerID=40&md5=107d0b838e6240758d8a504006bd8604","The Tibetan Plateau (TP) has an average elevation of over 4000m and with its surrounding mountains is regarded as Earth's ''third pole.'' As a result of its size and height, climate change in the TP has its own unique characteristics that include a proposed positive correlation between the surface temperature and pressure. This study examines the trends and relationships between the surface pressure and temperature in the TP through the examination of monthly mean data from 71 stations during 1961-2013. On annual, seasonal, and monthly time scales, the TP exhibits a statistically significant warming trend that attains a rate of 0.30°Cdecade-1 for annual means over the period 1961-2013. The most pronounced warming occurs in winter, in agreement with previous studies,with evidence of acceleration in the rate after the mid-1980s and the global warming slowdown period. For the entire period of 1961-2013, the surface pressure in the TP has a positive trend of 0.08 hPa decade-1 on an annual basis, again with the largest trends occurring in winter. However, unlike what occurred with the surface temperature, the trend in surface pressure, in most cases, reversed sign after the mid-1980s. The trend in the geopotential height at 500 hPa from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis is consistent with the observed surface pressure trends. Over the period 1961-2013, there is a seasonal shift in the nature of the relationship between the surface temperature and pressurewith a negative correlation during summer and autumn, and a positive correlation during winter. This suggests that the nature of the relationship between these two climate elements reflects the changing nature of the seasonal snow cover (land surface property) and cloud in the region. © 2017 American Meteorological Society."
"57197771454;","The functions and sizes of the five carbon sinks on planet earth and their relation to climate change part 2 coniferous forests-do they warm or cool the climate?",2017,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034645017&partnerID=40&md5=14173ee8400af5014cbe31df209df2ff","The UK Government and Forestry Commission state: “if we plant an additional 15, 000 hectares per year, by 2050 these woodlands could be sequestering carbon equivalent to 10% of GHG emissions”(1)(Appendix A). The inference is that by lowering atmospheric CO2 concentration with planting conifers climate cooling will follow. This is not so. This premise is wrong. Latitude-specific deforestation experiments indicate that afforestation projects in the tropics would be clearly beneficial in mitigating global-scale warming, but would be counterproductive if implemented at high latitudes (50-70N) and would offer only marginal benefits in temperate regions (40-60N). Although these results question the efficacy of mid- and high-latitude afforestation projects for climate mitigation, forests remain environmentally valuable resources for many reasons unrelated to climate.(2) GHGs produce their effects by increasing the retention of solar short wave radiation (lowering the albedo index (0 to 1) and by increasing radiative forcing measured in Watts per m-2, compared with the effects of an atmosphere of oxygen and nitrogen. Forests themselves and grassland or cropped land also absorb short wave radiation, but coniferous forests do so to a greater extent than does grassland, or field crops. Hence these forests increase radiative forcing – i.e. forestation, especially between the latitudes of 50 to 70 (virtually none in the southern hemisphere is at &gt;50 S) are liable to do so to an extent that exceeds the rate of their C sequestration in these colder latitudes, where there is less solar radiation. Moreover, as forest C sequestration reduces atmospheric CO2 at a rate that is a lower proportion of the amount sequestered, it is less effective than might be expected. This effect owes to a compensating release of CO2, especially from oceans but also from other vegetation (feedback). The net effect is positive for radiative forcing (Appendix A) for at least 90 % of UK coniferous forests. Forests may also increase water vapour in the atmosphere and so promote cloud formation - a useful function in arid climates. The influence of water vapour is likely to be variable and, although probably positive for radiative forcing, it is not accommodated in the calculations here, owing to a lack of reliable data. All people enjoy seeing trees. Nevertheless, we contend, especially in the present era with a rising world population and a scarcity of free land space, that afforestation should be carried out for the appropriate reasons, based upon reliable evidence. In the next Issue we shall describe how we consider this anomaly should be addressed and corrected. This will include a discussion of the life expectancy and effects of the cut timber which have not so far been considered by the protagonists of this subject. © 2017, Script Media Group Ltd. All rights reserved."
"24280225800;16637291100;9233045100;35119297700;23489993300;7201472576;","An intercomparison and validation of satellite-based surface radiative energy flux estimates over the Arctic",2017,"10.1002/2016JD026443","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018782055&doi=10.1002%2f2016JD026443&partnerID=40&md5=7227842d7d2fdbde3f7745daba33647f","Accurate determination of radiative energy fluxes over the Arctic is of crucial importance for understanding atmosphere-surface interactions, melt and refreezing cycles of the snow and ice cover, and the role of the Arctic in the global energy budget. Satellite-based estimates can provide comprehensive spatiotemporal coverage, but the accuracy and comparability of the existing data sets must be ascertained to facilitate their use. Here we compare radiative flux estimates from Clouds and the Earth’s Radiant Energy System (CERES) Synoptic 1-degree (SYN1deg)/Energy Balanced and Filled, Global Energy and Water Cycle Experiment (GEWEX) surface energy budget, and our own experimental FluxNet/ Satellite Application Facility on Climate Monitoring cLoud, Albedo and RAdiation (CLARA) data against in situ observations over Arctic sea ice and the Greenland Ice Sheet during summer of 2007. In general, CERES SYN1deg flux estimates agree best with in situ measurements, although with two particular limitations: (1) over sea ice the upwelling shortwave flux in CERES SYN1deg appears to be underestimated because of an underestimated surface albedo and (2) the CERES SYN1deg upwelling longwave flux over sea ice saturates during midsummer. The Advanced Very High Resolution Radiometer-based GEWEX and FluxNet-CLARA flux estimates generally show a larger range in retrieval errors relative to CERES, with contrasting tendencies relative to each other. The largest source of retrieval error in the FluxNet-CLARA downwelling shortwave flux is shown to be an overestimated cloud optical thickness. The results illustrate that satellite-based flux estimates over the Arctic are not yet homogeneous and that further efforts are necessary to investigate the differences in the surface and cloud properties which lead to disagreements in flux retrievals. Plain Language Summary The amounts of solar and thermal radiative energies toward and away from the Earth’s surface over the Arctic are the main driver of, e.g., the annual melt and freezing cycle of ice and snow. In this paper, we investigate how state-of-the-art satellite-based data sets of these radiative energy fluxes agree, or disagree, with each other and reference measurements made in the Arctic Ocean and on the Greenland Ice Sheet. We found that different data sets have not only individual strengths but also individual weaknesses which should be improved upon to enable a cohesive investigation of the radiative energy balance at annual and decadal time scales. © 2017. The Authors."
"56733854600;56978631100;56829983700;56978327500;56763004900;57095269100;56517029900;57214207021;56520903100;35265615300;7006593624;8075033200;","Effects of aqueous-phase and photochemical processing on secondary organic aerosol formation and evolution in Beijing, China",2017,"10.1021/acs.est.6b04498","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021852150&doi=10.1021%2facs.est.6b04498&partnerID=40&md5=78b5e1035f4ff296597f7a9ece4b53b5","Secondary organic aerosol (SOA) constitutes a large fraction of OA, yet remains a source of significant uncertainties in climate models due to incomplete understanding of its formation mechanisms and evolutionary processes. Here we evaluated the effects of photochemical and aqueous-phase processing on SOA composition and oxidation degrees in three seasons in Beijing, China, using high-resolution aerosol mass spectrometer measurements along with positive matrix factorization. Our results show that aqueous-phase processing has a dominant impact on the formation of more oxidized SOA (MO-OOA), and the contribution of MO-OOA to OA increases substantially as a function of relative humidity or liquid water content. In contrast, photochemical processing plays a major role in the formation of less oxidized SOA (LO-OOA), as indicated by the strong correlations between LO-OOA and odd oxygen (Ox = O3 + NO2) during periods of photochemical production (R2 = 0.59-0.80). Higher oxygen-to-carbon ratios of SOA during periods with higher RH were also found indicating a major role of aqueous-phase processing in changing the oxidation degree of SOA in Beijing. Episodes analyses further highlight that LO-OOA plays a more important role during the early stage of the formation of autumn/winter haze episodes while MO-OOA is more significant during the later evolution period. © 2016 American Chemical Society."
"35519380200;6603779272;57203052274;18133397500;57192695511;55850540800;8728433200;7102795549;7203040996;56140087300;56914807500;7004289296;57204699163;7003798647;36047973900;","Multidecadal trends in aerosol radiative forcing over the Arctic: Contribution of changes in anthropogenic aerosol to Arctic warming since 1980",2017,"10.1002/2016JD025321","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015299463&doi=10.1002%2f2016JD025321&partnerID=40&md5=1131f6c7e7e566fc5d5a94845da4b7af","Arctic observations show large decreases in the concentrations of sulfate and black carbon (BC) aerosols since the early 1980s. These near-term climate-forcing pollutants perturb the radiative balance of the atmosphere and may have played an important role in recent Arctic warming. We use the GEOS-Chem global chemical transport model to construct a 3-D representation of Arctic aerosols that is generally consistent with observations and their trends from 1980 to 2010. Observations at Arctic surface sites show significant decreases in sulfate and BC mass concentrations of 2-3% per year. We find that anthropogenic aerosols yield a negative forcing over the Arctic, with an average 2005-2010 Arctic shortwave radiative forcing (RF) of -0.19 ± 0.05Wm-2 at the top of atmosphere (TOA). Anthropogenic sulfate in our study yields more strongly negative forcings over the Arctic troposphere in spring (1.17 ± 0.10Wm 2) than previously reported. From 1980 to 2010, TOA negative RF by Arctic aerosol declined, from -0.67 ± 0.06Wm-2 to 0.19 ± 0.05Wm 2, yielding a net TOA RF of +0.48 ± 0.06Wm-2. The net positive RF is due almost entirely to decreases in anthropogenic sulfate loading over the Arctic. We estimate that 1980-2010 trends in aerosol-radiation interactions over the Arctic and Northern Hemisphere midlatitudes have contributed a net warming at the Arctic surface of +0.27 ± 0.04 K, roughly one quarter of the observed warming. Our study does not consider BC emissions from gas flaring nor the regional climate response to aerosol-cloud interactions or BC deposition on snow. © 2017. American Geophysical Union."
"55278297700;55543826100;57196180002;","Low-frequency oscillations of East Asia/Pacific teleconnection and simultaneous weather anomalies/extremes over eastern Asia",2017,"10.1002/joc.4703","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961815105&doi=10.1002%2fjoc.4703&partnerID=40&md5=9c12b3db1a34e91af658c187f4dd7e76","The East Asia/Pacific (EAP) teleconnection can substantially modulate weather anomalies over eastern Asia during summer. Wavelet analyses, including ensemble mean power spectrum and accumulated frequency of significant components, highlight 10–30-day oscillations in the EAP index. The influences of these low-frequency oscillations on weather anomalies are further investigated via both phase-dependent and lead-lag composites. On 10–30-day scales, a tripole structure of precipitation anomalies and a temperature seesaw form concurrently over adjacent regions along eastern Asia. These anomalies last for about 1 week, constituting anomalous weather spells with possible extreme values around the peak/valley phases. For cold spells over Northeast Asia during positive phases, the low-frequency easterly is the determinant factor. On one hand, it advects cold air from the sea east of the land. On the other hand, it conveys moisture to form low-based clouds, which are effective in inhibiting incoming solar radiation. While, for cold spells over central-eastern Siberia during negative phases, regional-scale precipitation and cold advections conveyed by anomalous northerlies combine to make contributions. Both hot spells over central-eastern Siberia/Northeast Asia during positive/negative phases mainly result from the adiabatic heating and increasing solar radiation, both of which are attributed to strong descent in response to upper-level convergences. In addition to great intensity, the high-impact property of these simultaneous weather anomalies also arises from their long duration and large spatial extent. By taking advantages of the quasi-periodicity of the 10–30-day oscillations, better predictions of these simultaneous weather anomalies/extremes would be anticipated. © 2016 Royal Meteorological Society"
"57191205447;42263280300;55796506900;","Impact of anthropogenic aerosols from global, East Asian, and non-East Asian sources on East Asian summer monsoon system",2017,"10.1016/j.atmosres.2016.08.023","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987925108&doi=10.1016%2fj.atmosres.2016.08.023&partnerID=40&md5=24407e394621339124756481bec51956","The impact of the total effects due to anthropogenic aerosols from global, East Asian, and non-East Asian sources on East Asian summer monsoon (EASM) system is studied using an aerosol-climate online model BCC_AGCM2.0.1_CUACE/Aero. The results show that the summer mean net all-sky shortwave fluxes averaged over East Asian monsoon region (EAMR) at the top of the atmosphere (TOA) and surface reduce by 4.8 and 5.0 W m− 2, respectively, due to the increases of global aerosol emissions in 2000 relative to 1850. Changes in radiations and their resulting changes in heat and water transport and cloud fraction contribute together to the surface cooling over EAMR in summer. The increases in global anthropogenic aerosols lead to a decrease of 2.1 K in summer mean surface temperature and an increase of 0.4 hPa in summer mean surface pressure averaged over EAMR, respectively. It is shown that the changes in surface temperature and pressure are significantly larger over land than ocean, thus decreasing the contrast of land-sea surface temperature and pressure. This results in the marked anomalies of north and northeast winds over eastern and southern China and the surrounding oceans in summer, thereby weakening the EASM. The summer mean precipitation averaged over the EAMR reduces by 12%. The changes in non-East Asian aerosol emissions play a more important role in inducing the changes of local temperature and pressure, and thus significantly exacerbate the weakness of the EASM circulation due to local aerosol changes. The weakening of circulation due to both is comparable, and even the effect of non-local aerosols is larger in individual regions. The changes of local and non-local aerosols contribute comparably to the reductions in precipitation over oceans, whereas cause opposite changes over eastern China. Our results highlight the importance of aerosol changes outside East Asia in the impact of the changes of anthropogenic aerosols on EASM. © 2016 Elsevier B.V."
"57189627805;7103098751;16199172000;7201951829;6504452801;","Hydrological controls on the tropospheric ozone greenhouse gas effect",2017,"10.1525/elementa.208","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020893244&doi=10.1525%2felementa.208&partnerID=40&md5=8ce5989017bb26bd218ee5384ef8ab14","The influence of the hydrological cycle in the greenhouse gas (GHG) effect of tropospheric ozone (O3) is quantified in terms of the O3 longwave radiative effect (LWRE), which is defined as the net reduction of top-of-atmosphere flux due to total tropospheric O3 absorption. The O3 LWRE derived from the infrared spectral measurements by Aura's Tropospheric Emission Spectrometer (TES) show that the spatiotemporal variation of LWRE is relevant to relative humidity, surface temperature, and tropospheric O3 column. The zonally averaged subtropical LWRE is ∼0.2 W m-2 higher than the zonally averaged tropical LWRE, generally due to lower water vapor concentrations and less cloud coverage at the downward branch of the Hadley cell in the subtropics. The largest values of O3 LWRE over the Middle East (&gt;1 W/m2) are further due to large thermal contrasts and tropospheric ozone enhancements from atmospheric circulation and pollution. Conversely, the low O3 LWRE over the Inter-Tropical Convergence Zone (on average 0.4 W m-2) is due to strong water vapor absorption and cloudiness, both of which reduce the tropospheric O3 absorption in the longwave radiation. These results show that changes in the hydrological cycle due to climate change could affect the magnitude and distribution of ozone radiative forcing. Copyright © 2017 The Author(s)."
"57197758169;57197755397;7004978335;16479754400;","Species richness and biomass of epiphytic vegetation in a tropical montane forest in western Panama",2017,"10.1177/1940082917698468","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034600504&doi=10.1177%2f1940082917698468&partnerID=40&md5=746f3e342034af450c7c80edd4bbc3d6","In tropical montane forests epiphytes represent a substantial proportion of biodiversity and green biomass, particularly where fog occurs almost daily. Epiphytes play important ecological roles in these ecosystems, for example, in forest hydrology and in amplifying arthropod biodiversity, but quantitative assessments of epiphytic biomass and species diversity are rare. Such data are important, however, for a better understanding on their ecological roles and as a baseline for detecting ecological change due to climate or land-use changes. In a tropical lower montane cloud forest (c. 1,150m above sea level) in Panama, we identified and weighed all epiphytic matter, which includes vascular plants, bryophytes, lichens, and dead organic matter from the trunks of 22 trees varying in diameters at breast height and 28 canopy branches. Additionally, we collected epiphytic matter in the understory in 22 plots of 2×2m. A total of 155 species of vascular epiphytes, hemiepiphytes, and nomadic vines were found. Orchidaceae were by far the most species-rich family, followed by Araceae and Bromeliaceae. The vertical distribution of these species in the forest showed species-specific vertical preferences, but species numbers varied little in undergrowth, trunks, and tree crowns. Epiphytic matter was positively related to tree size, and we used tree-size data inventory data from a nearby 1-ha plot to extrapolate our findings to the plot level. The resulting estimate of 16,439 kg ha-1 for total epiphytic matter and 6,214 kg ha-1 for living plants, the latter representing about 2% of aboveground forest biomass. © The Author(s) 2017."
"57196699811;24177361900;8633162900;","The impact of nonequilibrium and equilibrium fractionation on two different deuterium excess definitions",2017,"10.1002/2017JD027085","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037976708&doi=10.1002%2f2017JD027085&partnerID=40&md5=e978632d9e5ee87ecb5c1f238c0efce9","The deuterium excess (d) is a useful measure for nonequilibrium effects of isotopic fractionation and can therefore provide information about the meteorological conditions in evaporation regions or during ice cloud formation. In addition to nonequilibrium fractionation, two other effects can changed during phase transitions. The first is the dependence of the equilibrium fractionation factors on temperature, and the second is the nonlinearity of the δ scale on which d is defined. The second effect can be avoided by using an alternative definition that is based on the logarithmic scale. However, in this case d is not conserved when air parcels mix, which can lead to changes without phase transitions. Here we provide a systematic analysis of the benefits and limitations of both deuterium excess definitions by separately quantifying the impact of the nonequilibrium effect, the temperature effect, the δ-scale effect, and the mixing effect in a simple Rayleigh model simulating the isotopic composition of air parcels during moist adiabatic ascent. The δ-scale effect is important in depleted air parcels, for which it can change the sign of the traditional deuterium excess in the remaining vapor from negative to positive. The alternative definition mainly reflects the nonequilibrium and temperature effect, while the mixing effect is about 2 orders of magnitude smaller. Thus, the alternative deuterium excess definition appears to be a more accurate measure for nonequilibrium effects in situations where moisture is depleted and the δ-scale effect is large, for instance, at high latitudes or altitudes. © 2017. American Geophysical Union. All Rights Reserved."
"16308514000;55350802700;56210720700;7102913661;35105101800;6602221672;15080710300;57203776263;6603372665;18134565600;8359591200;7102336894;","Contrasting aerosol refractive index and hygroscopicity in the inflow and outflow of deep convective storms: Analysis of airborne data from DC3",2017,"10.1002/2017JD026638","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018964476&doi=10.1002%2f2017JD026638&partnerID=40&md5=67672ca4e8c0283821d395b7e11ecf39","We examine three case studies during the Deep Convective Clouds and Chemistry (DC3) field experiment when storm inflow and outflow air were sampled for aerosol subsaturated hygroscopicity and the real part of refractive index (n) with a Differential Aerosol Sizing and Hygroscopicity Probe (DASH-SP) on the NASA DC-8. Relative to inflow aerosol particles, outflow particles were more hygroscopic (by 0.03 based on the estimated κ parameter) in one of the three storms examined. Two of three “control” flights with no storm convection reveal higher κ values, albeit by only 0.02, at high altitude (> 8 km) versus < 4 km. Entrainment modeling shows that measured κ values in the outflow of the three storm flights are higher than predicted values (by 0.03-0.11) based on knowledge of κ values from the inflow and clear air adjacent to the storms. This suggests that other process(es) contributed to hygroscopicity enhancements such as secondary aerosol formation via aqueous-phase chemistry. Values of n were higher in the outflow of two of the three storm flights, reaching as high as 1.54. More statistically significant differences were observed in control flights (no storms) where n decreased from 1.50-1.52 (< 4 km) to 1.49-1.50 (> 8 km). Chemical data show that enhanced hygroscopicity was coincident with lower organic mass fractions, higher sulfate mass fractions, and higher O: C ratios of organic aerosol. Refractive index did not correlate as well with available chemical data. Deep convection is shown to alter aerosol radiative properties, which has implications for aerosol effects on climate. © 2017. American Geophysical Union."
"18635820300;","A technique for verification of convection-permitting NWP model deterministic forecasts of lightning activity",2017,"10.1175/WAF-D-16-0106.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010194184&doi=10.1175%2fWAF-D-16-0106.1&partnerID=40&md5=8fd73a7a85feb3b03946dfbd91d593a0","This manuscript introduces a new technique for evaluating lightning forecasts from convection-permitting models. In recent years, numerical weather prediction models at the convection-permitting scales (horizontal grid resolutions of 1-5 km) have been able to produce realistic-looking forecasts of lightning activity when compared with observations. However, it is challenging to assess what value these forecasts add above standard large-scale indices. Examining this problem, it is found that existing skill scores and neighborhood verification methods are unable to cope with both the double-penalty effect and the model's variable frequency bias. A displacement distance and a quasi-symmetric distance score are introduced based on the distance between the model and the observations, the latter showing any improvement the forecast has over a completely ""hedged"" forecast. This can be combined with a domain-improved contingency table and comparisons between modeled and observed lightning flashes to evaluate the forecast performance in three important dimensions: coverage, distance, and intensity. The verification metric is illustrated with a single case, which shows that the convective-scale U.K. variable resolution model (UKV) delivers improved forecasts compared with the large-scale indices in both coverage and distance. Additionally, a month-long analysis is performed, which reveals that the coverage of lightning is in good agreement with the observations; lightning is displaced by the model by a distance on the order of 50-75 km, but the model overpredicts the lightning intensity by at least a factor of 6 after observational detection efficiencies have been considered. © 2017 American Meteorological Society."
"57195775759;36617082000;","Prediction of hospitalizations caused by respiratory diseases by using data mining techniques: Some applications in Curitiba, Brazil and the metropolitan area",2017,"10.2495/AIR170231","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029788810&doi=10.2495%2fAIR170231&partnerID=40&md5=5fb80c4ab070a7d875ec79106165b994","As seen throughout the years, the industrial and technological evolution led to problems that evolved from the constant growth of the globalized economic world, among many other features. One of them is air pollution, which is co-related to human health and welfare. The city of Curitiba and its metropolitan area comprise around 3.5 million people, which are directly affected by over 1 million vehicles in the capital, and the diversified industries that continue to grow. This project consists of combining hospitalization data and other related urban variables such as climate and air pollution. This paper describes the methodology by using a data mining approach to explore data from 2008 to 2016 from Curitiba and six other cities. The aim of this study is to predict future cases of hospitalizations caused by respiratory diseases in Curitiba and the metropolitan area, and to consider atmospheric and air quality. The air pollution parameters used in this study are: suspended particles matter; PM10 (particles smaller or equal to 10 micrometers); sulfur dioxide (SO2); carbon monoxide (CO); ozone (O3); nitrogen dioxide (NO2); and the air quality index (AQI). The climate variables are: wind direction; average wind speed; average maximum wind speed; potential and real evaporation; insolation; average cloud cover; total precipitation and days of precipitation; average atmospheric pressure; minimum, maximum and average temperature; and relative humidity. The results of this scientific project may be used by the government for developing actions and interventions aimed at minimizing the adverse effects on the environment and human health. It is also expected that the results could contribute to the planning of environmental, controlling air pollution and improving public policies. © 2017 WIT Press."
"55355215900;42962694100;","The influence of urban surface expansion in China on regional climate",2017,"10.1175/JCLI-D-15-0604.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010874934&doi=10.1175%2fJCLI-D-15-0604.1&partnerID=40&md5=f7a54512693a3ad32a743492f70c1446","Incorporating satellite-based urban surface data for the 1980s, 1990s, 2000s, and 2010s in China, contributions to regional warming, and changes in the precipitation due to urban surface expansion were explored using the nested Fifth-generation Pennsylvania State University-NCAR Mesoscale Model version 3.7 (MM5V3.7) with urban effects considered. The impact on surface air temperature at 2 m (SAT) due to urban surface expansion between the 1980s and the 2010s revealed that annual urban-related warming was lower over East Asia (0.031°C) and China (0.075°C) but higher in eastern China (0.14°C), which experienced dramatic urbanization. Greater warming could be detected over urban surface areas in the three city clusters [Beijing-Tianjin-Hebei (BTH) and the Yangtze and Pearl River deltas (YRD and PRD, respectively)], which reached 1.06°, 0.84°, and 0.92°C, respectively. Urban-related warming was not limited to a single city or city clusters but extended over a SAT-increased belt that covered the eastern coast of China. Further analysis showed that urban-surface-expansion-induced changes in albedo and the total cloud amount contributed to the changes in the radiation budget, which resulted in strong surface radiative forcings in the urban surface (14.5, 11.2, and 11.7 W m-2 for BTH, YRD, and PRD, respectively). However, significant differences could be detected for the transition from nonurban to urban land use compared to those that were classified as urban in both time periods because of the varied albedo changes. The urbanization-related warming, especially in the city cluster areas, also had a further effect on the large-scale circulation and precipitation. The precipitation was weakened in northeastern and northern China but intensified in eastern and southern China, which resulted in the strengthened precipitation over China (0.016 mm day-1, 0.65%) and East Asia (0.011 mm day-1, 0.28%). Therefore, subregional characteristics with marked seasonal, interannual, and decadal variations were detected for the influence of the urban surface expansion."
"21742081100;7004090168;35107726100;7401856520;","Precipitation stable isotope variability and subcloud evaporation processes in a semi-arid region",2017,"10.1002/hyp.10885","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984696273&doi=10.1002%2fhyp.10885&partnerID=40&md5=78fe7991ed37e7223a6db8d88857c829","The stable isotopic (2H/1H and 18O/16O) composition of precipitation has been used for a variety of hydrological and paleoclimate studies, a starting point for which is the behaviour of stable isotopes in modern precipitation. To this end, daily precipitation samples were collected over a 7-year period (2008–2014) at a semi-arid site located at the Macquarie Marshes, New South Wales (Australia). The samples were analysed for stable isotope composition, and factors affecting the isotopic variability were investigated. The best correlation between δ18O of precipitation was with local surface relative humidity. The reduced major axis precipitation weighted local meteoric water line was δ2H = 7.20 δ18O + 9.1. The lower slope and intercept (when compared with the Global Meteoric Water Line) are typical for a warm dry climate, where subcloud evaporation of raindrops is experienced. A previously published model to estimate the degree of subcloud evaporation and the subsequent isotopic modification of raindrops was enhanced to include the vertical temperature and humidity profile. The modelled results for raindrops of 1.0 mm radius showed that on average, the measured D-excess (=δ2H − 8 δ18O) was 19.8‰ lower than that at the base of the cloud, and 18% of the moisture was evaporated before ground level (smaller effects were modelled for larger raindrops). After estimating the isotopic signature at the base of the cloud, a number of data points still plotted below the global meteoric water line, suggesting that some of the moisture was sourced from previously evaporated water. Back trajectory analysis estimated that 38% of the moisture was sourced over land. Precipitation samples for which a larger proportion of the moisture was sourced over land were 18O and 2H-enriched in comparison to samples for which the majority of the moisture was sourced over the ocean. The most common weather systems resulting in precipitation were inland trough systems; however, only East Coast Lows contributed to a significant difference in the isotopic values. Copyright © 2016 Australian Nuclear Science and Technology Organisation. Hydrological Processes. © 2016 John Wiley &amp; Sons, Ltd. Copyright © 2016 Australian Nuclear Science and Technology Organisation. Hydrological Processes. © 2016 John Wiley & Sons, Ltd."
"35752249500;7006044529;56498662800;13411085200;55476786400;36986635700;","Solar irradiance nowcasting case studies near sacramento",2017,"10.1175/JAMC-D-16-0183.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009458336&doi=10.1175%2fJAMC-D-16-0183.1&partnerID=40&md5=1b994ac4bb3aa378f1d2a6101288c4a4","The Sun4Cast solar power forecasting system, designed to predict solar irradiance and power generation at solar farms, is composed of several component models operating on both the nowcasting (0-6 h) and day-ahead forecast horizons. The different nowcasting models include a statistical forecasting model (StatCast), two satellite-based forecasting models [the Cooperative Institute for Research in the Atmosphere Nowcast (CIRACast) and the Multisensor Advection-Diffusion Nowcast (MADCast)], and a numerical weather prediction model (WRF-Solar). It is important to better understand and assess the strengths and weaknesses of these short-range models to facilitate further improvements. To that end, each of these models, including four WRF-Solar configurations, was evaluated for four case days in April 2014. For each model, the 15-min average predicted global horizontal irradiance (GHI) was compared with GHI observations from a network of seven pyranometers operated by the Sacramento Municipal Utility District (SMUD) in California. Each case day represents a canonical sky-cover regime for the SMUD region and thus represents different modeling challenges. The analysis found that each of the nowcasting models perform better or worse for particular lead times and weather situations. StatCast performs best in clear skies and for 0-1-h forecasts; CIRACast and MADCast perform reasonably well when cloud fields are not rapidly growing or dissipating; and WRF-Solar, when configured with a high-spatial-resolution aerosol climatology and a shallow cumulus parameterization, generally performs well in all situations. Further research is needed to develop an optimal dynamic blending technique that provides a single best forecast to energy utility operators."
"12143017100;35273743200;","Different climatological characteristics, inner-core structures, and intensification processes of simulated intense tropical cyclones between 20-km global and 5-km regional models",2017,"10.1175/JCLI-D-16-0093.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014045481&doi=10.1175%2fJCLI-D-16-0093.1&partnerID=40&md5=ac05f4cd84250c05f5448ea75e5e4761","Climatological characteristics of simulated intense tropical cyclones (TCs) in the western North Pacific were explored with a 20-km-mesh atmospheric general circulation model (AGCM20) and a 5-km-mesh regional atmospheric nonhydrostatic model (ANHM5). From the AGCM20 climate runs, 34 intense TCs with a minimum central pressure (MCP) less than or equal to 900 hPa were sampled. Downscaling experiments were conducted with the ANHM5 for each intense TC simulated by the AGCM20. Only 23 developed into TCs withMCP#900 hPa. Most of the best-track TCs with anMCP#900 hPa underwent rapid intensification (RI) and attained maximum intensities south of 258N. The AGCM20 simulated a similar number of intense TCs as the best-track datasets. However, the intense AGCM20 TCs tended to intensify longer and more gradually; only half of them underwent RI. The prolonged gradual intensification resulted in significant northward shifts of the location of maximum intensity compared with the location derived from two best-track datasets. The inner-core structure of AGCM20 TCs exhibited weak and shallow eyewall updrafts with maxima below an altitude of 6 km, while downscaling experiments revealed that most of the intenseANHM5TCs underwent RI with deep and intense eyewall updrafts and attained their maximumintensity at lower latitudes. The altitudes of updraft maxima simulated by the AGCM20 descended rapidly during the phase of greatest intensification as midlevel warming markedly developed. The change in major processes responsible for precipitation in AGCM20 TCs before and after maximum intensification suggests close relationships between the large-scale cloud scheme and midlevel warming and prolonged gradual intensification. © 2017 American Meteorological Society."
"23013131500;57191830919;6603943978;7004962346;6701628795;56271306100;7005661275;6603163912;7003372226;56257109300;","The impact of Mount Etna sulfur emissions on the atmospheric composition and aerosol properties in the central Mediterranean: A statistical analysis over the period 2000–2013 based on observations and Lagrangian modelling",2017,"10.1016/j.atmosenv.2016.10.032","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994045392&doi=10.1016%2fj.atmosenv.2016.10.032&partnerID=40&md5=612c1aaea2e0444e5466f1fbebe41650","The emission of gases and aerosols due to volcanic activity may impact significantly atmospheric composition, cloud occurrence and properties, and the regional and global climate. While the effects of strong explosive (stratospheric) eruptions are relatively well known, limited information on the impacts of small to moderate volcanic activities, including passive degassing, is available. In this paper, the downwind impact of Mount Etna's sulfur emissions on the central Mediterranean is investigated on a statistical basis over the period 2000–2013 using: (a) daily sulfur dioxide emission rates measured near crater at Mount Etna with ground-based ultraviolet spectrophotometers, (b) Lagrangian trajectories and simulated plume dispersion obtained with the FLEXPART (FLEXible PARTicle dispersion) model, and (c) long-term observations of column SO2 concentration and aerosol Ångström exponent α at Lampedusa (35.5° N, 12.6° E). This statistical analysis has allowed, for the first time, the characterization of decadal impact of Mount Etna's sulfur emissions on the sulfur dioxide and the aerosol microphysical/optical properties in the central Mediterranean. On average, statistically significant higher SO2 concentrations and smaller aerosol sizes are present when air masses from Mount Etna overpass Lampedusa. Despite being upwind of Lampedusa for only 5% of the time, Mount Etna is potentially responsible for up to 40% and 20% of the SO2 and α extreme values (exceedances of a fixed threshold), respectively, at this location. The most important factor determining this perturbation is the prevailing dynamics, while the magnitude of the SO2 emission rates from Mount Etna appears to be likely important only for relatively strong emissions. The observed perturbations to the aerosol size distribution are expected to produce a direct regional radiative effect in this area. © 2016 Elsevier Ltd"
"7401822381;56981032200;56022412200;","Glacial density and GIA in Alaska estimated from ICESat, GPS and GRACE measurements",2017,"10.1002/2016JF003926","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013035826&doi=10.1002%2f2016JF003926&partnerID=40&md5=3280d936ffb6ea5c91f86d7b263c7cc7","The density of glacial volume change in Alaska is a key factor in estimating the glacier mass loss from altimetry observations. However, the density of Alaskan glaciers has large uncertainty due to the lack of in situ measurements. In this paper, using the measurements of Ice, Cloud, and land Elevation Satellite (ICESat), Global Positioning System (GPS), and Gravity Recovery and Climate Experiment (GRACE) from 2003 to 2009, an optimal density of glacial volume change with 750 kg/m3 is estimated for the first time to fit the measurements. The glacier mass loss is −57.5 ± 6.5 Gt by converting the volumetric change from ICESat with the estimated density 750 kg/m3. Based on the empirical relation, the depth-density profiles are constructed, which show glacial density variation information with depths in Alaska. By separating the glacier mass loss from glacial isostatic adjustment (GIA) effects in GPS uplift rates and GRACE total water storage trends, the GIA uplift rates are estimated in Alaska. The best fitting model consists of a 60 km elastic lithosphere and 110 km thick asthenosphere with a viscosity of 2.0 × 1019 Pa s over a two-layer mantle. ©2016. American Geophysical Union. All Rights Reserved."
"18133397500;57192695511;7404548584;6701718281;56604019400;6603652793;","Mesoscale modeling of smoke transport from equatorial Southeast Asian Maritime Continent to the Philippines: First comparison of ensemble analysis with in situ observations",2017,"10.1002/2016JD026241","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019395442&doi=10.1002%2f2016JD026241&partnerID=40&md5=f66b9652cdede008e4a0b4a1db363ce4","Atmospheric transport of smoke from equatorial Southeast Asian Maritime Continent (Indonesia, Singapore, and Malaysia) to the Philippines was recently verified by the first-ever measurement of aerosol composition in the region of the Sulu Sea from a research vessel named Vasco. However, numerical modeling of such transport can have large uncertainties due to the lack of observations for parameterization schemes and for describing fire emission and meteorology in this region. These uncertainties are analyzed here, for the first time, with an ensemble of 24 Weather Research and Forecasting model with Chemistry (WRF-Chem) simulations. The ensemble reproduces the time series of observed surface nonsea-salt PM2.5 concentrations observed from the Vasco vessel during 17-30 September 2011 and overall agrees with satellite (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and Moderate Resolution Imaging Spectroradiometer (MODIS)) and Aerosol Robotic Network (AERONET) data. The difference of meteorology between National Centers for Environmental Prediction (NCEP’s) Final (FNL) and European Center for Medium range Weather Forecasting (ECMWF’s) ERA renders the biggest spread in the ensemble (up to 20 µg m-3 or 200% in surface PM2.5), with FNL showing systematically superior results. The second biggest uncertainty is from fire emissions; the 2 day maximum Fire Locating and Modelling of Burning Emissions (FLAMBE) emission is superior than the instantaneous one. While Grell-Devenyi (G3) and Betts-Miller-Janjic cumulus schemes only produce a difference of 3 µgm-3 of surface PM2.5 over the Sulu Sea, the ensemble mean agrees best with Climate Prediction Center (CPC) MORPHing (CMORPH)‘s spatial distribution of precipitation. Simulation with FNL-G3, 2 day maximum FLAMBE, and 800 m injection height outperforms other ensemble members. Finally, the global transport model (Navy Aerosol Analysis and Prediction System (NAAPS)) outperforms all WRF-Chem simulations in describing smoke transport on 20 September 2011, suggesting the challenges to model tropical meteorology at mesoscale and finer scale. Plain Language Summary It is well known that smoke particles from fires in Indonesia, Singapore, and Malaysia can affect each other’s air quality. Less known and surely not well documented is the transport of smoke particles from these countries to the Philippines. Here we use the first-ever measurements took nearby the coastal of the Philippines to analyze an ensemble of 24 WRF-Chem simulations of smoke transport. Because of persistent cloud cover and the complexity of meteorology, mesoscale modeling of smoke transport in these regions normally has large uncertainties. We show these uncertainties are caused first by meteorology and then by fire emissions. We further show that models with finer resolution not necessarily produce better results. © 2017. American Geophysical Union. All Rights Reserved."
"35768178600;57053165400;7006069664;57203474131;","Prediction of rapid intensification of tropical cyclone Phailin over the Bay of Bengal using the HWRF modelling system",2017,"10.1002/qj.2956","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015347637&doi=10.1002%2fqj.2956&partnerID=40&md5=a4c4e0607df7932f1782a2c2fe64a6b0","The study objective is to assess the impact of cloud-permitting resolution and improved representation of multiscale processes on the ability to predict rapid intensification (RI) and structure of Phailin (2013), one of the strongest tropical cyclones (TCs) over the Bay of Bengal. The state-of-the-art Hurricane Weather Research and Forecasting (HWRF) modelling system is used with two different configurations. The first configuration uses a static domain of 27 km grid size with a movable nested domain of 9 km grid size (hereafter H2D). The second configuration has an additional movable nested domain of 3 km grid size (known as H3D) to resolve meso- and vortex-scale features respectively. The results clearly show the ability of the H3D system at cloud-permitting resolution (3 km) in predicting the TC movement, intensity and structure. The storm-to-vortex scale interaction in H3D allowed for better prediction of large-scale wind flow, low-level wind asymmetry and PV tendency, and provided insight to improve track predictions. The vortex depth is another important factor and the shallow vortex in the H2D run interacted differently with the large-scale environment and resulted in large track and intensity errors. Substantial gains are noticed in RI and structure prediction, mainly due to better simulation of diabatic heating, strong inflow, and moisture distribution in H3D, where the intensity errors are ≤11 knots (5.6 m s−1) up to the 72 h forecast, and up to 40 knots (20.5 m s−1) in the H2D version. The upper-level warming is well resolved in the H3D as compared to the H2D run. In summary, this study highlights the need for considering multiscale interactions and improved physics along with high-resolution initialization to resolve convective processes in the vortex and to realistically predict track, structure, and intensity changes. © 2016 Royal Meteorological Society"
"55321749800;7006468812;57094265300;56385279100;","A comparison of Haze removal algorithms and their impacts on classification accuracy for landsat imagery [Comparação entre algoritmos de remoção de neblina e seu impacto na acurácia da classificação de imagens Landsat]",2017,"10.1590/S1982-21702017000100004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016326780&doi=10.1590%2fS1982-21702017000100004&partnerID=40&md5=f68e3aab038dcace12f083a822e6ef0d","The quality of Landsat images in humid areas is considerably degraded by haze in terms of their spectral response pattern, which limits the possibility of their application in using visible and near-infrared bands. A variety of haze removal algorithms have been proposed to correct these unsatisfactory illumination effects caused by the haze contamination. The purpose of this study was to illustrate the difference of two major algorithms (the improved homomorphic filtering (HF) and the virtual cloud point (VCP)) for their effectiveness in solving spatially varying haze contamination, and to evaluate the impacts of haze removal on land cover classification. A case study with exploiting large quantities of Landsat TM images and climates (clear and haze) in the most humid areas in China proved that these haze removal algorithms both perform well in processing Landsat images contaminated by haze. The outcome of the application of VCP appears to be more similar to the reference images compared to HF. Moreover, the Landsat image with VCP haze removal can improve the classification accuracy effectively in comparison to that without haze removal, especially in the cloudy contaminated area. © 2017, Universidade Federal do Parana. All rights reserved."
"55731174900;56249234900;57216579009;55313019700;7005231450;","Impact of Chinese urbanization and aerosol emissions on the East Asian summer monsoon",2017,"10.1175/JCLI-D-15-0593.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010850396&doi=10.1175%2fJCLI-D-15-0593.1&partnerID=40&md5=5cf2ac082292e874c3ae0a0d01572352","Impacts of urbanization and anthropogenic aerosols in China on the East Asian summer monsoon (EASM) are investigated using version 5.1 of the Community Atmosphere Model (CAM5.1) by comparing simulations with and without incorporating urban land cover and/or anthropogenic aerosol emissions. Results show that the increase of urban land cover causes large surface warming and an urban frictional drag, both leading to a northeasterly wind anomaly in the lower troposphere over eastern China (EC). This weakens the southerly winds associated with the EASM and causes a convergence anomaly in southern China (SC) with increased ascent, latent heating, and cloudiness. The enhanced latent heating reinforces surface convergence and upper-level divergence over SC, leading to more northward advection in the upper level into northern China (NC) and descending between 30° and 50°N over East Asia. Cloudiness reduction, adiabatic heating, and warm advection over NC all enhance the urban heating there, together causing anomalous tropospheric warming at those latitudes over East Asia. Anthropogenic aerosols cause widespread cooling at the surface and in the troposphere over EC, which decreases the summer land-ocean thermal contrast, leading to a weakened EASM circulation with reduced moisture transport to NC. This results in wetter and drier conditions over SC and NC, respectively. When both the urbanization and anthropogenic aerosols are included in the model, aerosols' cooling is partially offset by the urban heating, and their joint effect on the circulation is dominated by the aerosols' effect with a reduced magnitude. In the combined experiment, surface and tropospheric temperatures are also altered by the decrease (increase) in cloudiness over NC (SC) with most of the cooling confined to SC, which further weakens the EASM circulation."
"55064462800;36810454400;6603583479;7004322831;6602149014;55414110100;55875745200;35801031800;","Forests dynamics in the montane-alpine boundary: A comparative study using satellite imagery and climate data",2017,"10.3354/cr01452","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028909072&doi=10.3354%2fcr01452&partnerID=40&md5=2bc31afe9c17ef26c743df383c430ba2","Over the past decades, the altitudinal and latitudinal advance of forest lines has increased due to global warming and the abandonment of less productive areas previously subject to agricultural activities. The intensity and speed of the forest line advance also depend on numerous physical, biological and human factors that are region-specific. It is important to fully understand the mechanisms behind forest line behaviour, as existing studies do not report global figures. We selected 4 study areas in which to analyse the temporal and spatial behaviour of the forest line and of forest cover based on selection criteria such as minimal human interference and maximal representativeness at the European level. The sites were located in national parks that were evenly spread across some of the dominant European mountain ranges such as the Pyrenees, Alps and Carpathians, at comparable altitudes and latitudes, and with similar land cover proportions in the year 1970. Methodologically, we used cloud-free Landsat satellite images that were acquired in the same month during the growing season. A post-classification comparison technique, using all bands but the thermal one, was implemented to evaluate forest line behaviour, while the accuracy of image classification was evaluated by random sampling. Four time frames were used to evaluate forest cover behaviour in relation to the non-forested areas: 1971-1980, 1981-1990, 1991-2000 and 2001-2014. Also, climate and topography data were included in this study, which enabled comparison and computation of dependence relations. Our results indicate significant differences between the analysed areas. For instance, for the same reference period (1981-1990), the greatest differences in terms of forest cover change were specific to the Austrian Alps (28%), whereas the lowest differences were those from the Spanish Pyrenees (1%). Similar forest line shifts were found in the Austrian Alps and in the Romanian Carpathians, whereas the lowest altitudinal advancement was specific to the Spanish Pyrenees. According to this study, the temperature trend could have significantly influenced tree line behaviour. © The authors 2017."
"55949396100;35265615300;38762392200;25936649000;57214207021;36468123600;55949765200;55545335600;55822818500;37020139300;","Estimation of atmospheric aging time of black carbon particles in the polluted atmosphere over central-eastern China using microphysical process analysis in regional chemical transport model",2017,"10.1016/j.atmosenv.2017.05.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019733911&doi=10.1016%2fj.atmosenv.2017.05.016&partnerID=40&md5=070c153e91aee0eae0485232781202e4","Mixing state of black carbon (BC) particles has significant impacts on their radiative forcing, visibility impairment and the ability in modifying cloud formation. In this study, an aging scheme of BC particles using prognostic variables based on aerosol microphysics was incorporated into a regional atmospheric chemistry model, Nested Air Quality Prediction Modeling System with Advanced Particle Microphysics (NAQPMS + APM), to investigate the temporal and spatial variations in aging time scale of BC particles in polluted atmosphere over central-eastern China. The model results show that the aging time scale has a clear diurnal variation with a lower value in the daytime and a higher value in the nighttime. The shorter aging time scale in the daytime is due to condensation aging associated with intense photochemical reaction while the longer aging time scale in the nighttime is due to coagulation aging, which is much slower than that due to condensation. In Beijing, the aging time scale is 2 h or less in the surface layer in daytime, which is far below the fixed 1.2 days used in many models. As a result, the fraction of hydrophilic BC particles by the new scheme is larger than that by the scheme with fixed aging time scale though the mean aging time scale by the new scheme is much larger than 1.2 days. Hydrophilic fraction of BC particles increases with the increase of height. Over central-eastern China, the averaged aging time scale calculated by the new scheme is in the range from 12 h to 7 days, with higher values in regions far from the source areas. Hydrophilic fraction of BC particles is more than 90% at the higher levels in polluted atmosphere. Difference of simulated BC concentration with internal mixing and microphysical aging is within 5%, indicating that the assumption of internal mixing for BC particles to respond to in-cloud scavenging is more appropriate than the external mixing assumption in polluted atmosphere over central-eastern China. © 2017 Elsevier Ltd"
"53986492000;57193536299;57196087358;","One year record of bioaerosols and particles concentration in Indo-Gangetic Plain: Implications of biomass burning emissions to high-level of endotoxin exposure",2017,"10.1016/j.envpol.2017.01.045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014668492&doi=10.1016%2fj.envpol.2017.01.045&partnerID=40&md5=25e933bae7c61ec300a6e3282fa08604","Previous studies worldwide have suggested the potential role of bioaerosols as ice-nuclei and cloud-condensation nuclei. Furthermore, their participation in regulating the global carbon cycle urges systematic studies from different environmental conditions throughout the globe. Towards this through one-year study, conducted from June 2015–May 2016, we report on atmospheric abundance and variability of viable bioaerosols, organic carbon (OC) and particles number and deduced mass concentrations from Indo-Gangetic Plain (IGP; at Kanpur). Among viable bioaerosols, the highest concentrations of Gram-positive bacteria (GPB), Gram-negative bacteria (GNB) and Fungi were recorded during December–January (Avg.: 189 CFU/m3), November (244 CFU/m3) and September months (188 CFU/m3), respectively. Annual average concentration of GPB, GNB and Fungi were 105 ± 58, 144 ± 82 and 116 ± 51 CFU/m3. Particle number concentration (PNC) associated with fine-fraction aerosols (FFA) predominates throughout the year. However, mineral dust (coarser particle) remains a perennial constituent of atmospheric aerosols over the IGP. Temporal variability records and significant positive linear relationship (p &lt; 0.05) of GPB and GNB with OC and biomass burning derived potassium (K+ BB) indicates their association with massive emissions from paddy-residue burning (PRB) and bio-fuel burning. Influence of meteorological parameters on viable bioaerosols abundance has been rigorously investigated herein. Accordingly, ambient temperature seems to be more affecting the bacteria (anti-correlation), whereas wet-precipitation (1–4 mm) relates to higher abundance of Fungi. High abundance of GNB during large-scale biomass burning emissions has implications to endotoxin exposure on human health. Field-based data-set of bioaerosols, OC, PNC and deduced mass concentrations reported herein could serve to better constraint their role in human health and climate relevance. © 2017 Elsevier Ltd"
"57188971800;7005054220;7404327420;7102913661;55314628400;56591838400;7102965584;56893853800;15135583300;7004165697;7003479494;6506458269;7003597162;","Evaluation of deep convective transport in storms from different convective regimes during the DC3 field campaign using WRF-Chem with lightning data assimilation",2017,"10.1002/2017JD026461","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021839484&doi=10.1002%2f2017JD026461&partnerID=40&md5=0b589c76629f966c898157ba7018c82b","Deep convective transport of surface moisture and pollution from the planetary boundary layer to the upper troposphere and lower stratosphere affects the radiation budget and climate. This study analyzes the deep convective transport in three different convective regimes from the 2012 Deep Convective Clouds and Chemistry field campaign: 21 May Alabama air mass thunderstorms, 29 May Oklahoma supercell severe storm, and 11 Junemesoscale convective system (MCS). Lightning data assimilation within the Weather Research and Forecasting (WRF) model coupled with chemistry (WRF-Chem) is utilized to improve the simulations of storm location, vertical structure, and chemical fields. Analysis of vertical flux divergence shows that deep convective transport in the 29 May supercell case is the strongest per unit area, while transport of boundary layer insoluble trace gases is relatively weak in theMCS and airmass cases. Theweak deep convective transport in the strong MCS is unexpected and is caused by the injection into low levels of midlevel clean air by a strong rear inflow jet. In each system, the magnitude of tracer vertical transport is more closely related to the vertical distribution of mass flux density than the vertical distribution of trace gas mixing ratio. Finally, the net vertical transport is strongest in high composite reflectivity regions and dominated by upward transport. © 2017. American Geophysical Union. All Rights Reserved."
"54881950900;21740519000;7004854393;","Morphology of breeze circulations induced by surface flux heterogeneities and their impact on convection initiation",2017,"10.1002/qj.2935","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007197344&doi=10.1002%2fqj.2935&partnerID=40&md5=9f9ce4d6f5e9e9727c66bf142c689547","This study analyses the role of breeze circulations induced by a surface sensible heat flux heterogeneity on deep convection initiation. Large-eddy simulations are used to disentangle the processes at play in a typical case of daytime triggering of deep convection over a semi-arid land. We show that the presence of a realistic surface sensible heat flux heterogeneity leads to an earlier triggering of convection and induces a strong determinism in the triggering location at the beta-mesoscale (i.e. ∼50 km). The transition to deep convection consists of three consecutive stages, each one corresponding to a specific mode of interaction between (i) the boundary-layer thermals (small-scale), (ii) the breeze circulation (mesoscale) and (iii) the background wind (synoptic scale). These stages are both interpreted thermodynamically and morphologically. All along the transition phase, the boundary-layer growth acts to slow down the background wind, which strengthens the breeze circulation. The breeze evolves towards a circular shape which optimizes moisture convergence and cloud formation just prior to triggering. The presence of wind shear leads with a more asymmetric shape of the breeze in the afternoon, associated with a preferential triggering on the down-shear side of the breeze circulation. © 2016 Royal Meteorological Society"
"57193360427;56451455100;","Green-energy, water-autonomous greenhouse system: An alternative-technology approach towards sustainable smart-green vertical greening in smart cities",2017,"10.14246/irspsd.5.1_55","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013347182&doi=10.14246%2firspsd.5.1_55&partnerID=40&md5=96ccf34e9dcdd1a8c4e3a88e9b169f9e","By means of ""going greener"", ""getting smarter"" and ""converging smart-green"", an innovation-driven smart city could address the steps toward more sustainability and aim toward improved human well-being. A vertical greening means a vertical triumph of greenery in a high density urban area, in some ways it displays the level of smartness and greenness in a city. Researchers have suggested the use of vertical greening in urban areas to improve sustainability of the environment. However, conventional vertical greening is in open fields, unprotected, threatened by climate disasters, lacking in better controlled climate conditions and plant response-based circumstances. In addition are always the challenges of energy saving, reduction of CO2 emissions, reduction in water use and in pesticide use. A greenhouse system could instead solve different facets of these problems in conventional vertical greening to achieve an optimal balance between an efficient environmental control and efficient plant use of available resources. The greenhouse solution appears to be intellectually justifiable, adaptable and innovative, and appears beneficial to a smart-green and sustainable smart city. Through the literature review and foresighted design point of view, the paper first summarizes the major concepts and trends of smart cities, vertical greening usage and new greenhouse technologies, and approaches an introduction to the relationship and development between vertical greening and greenhouse systems, and is followed by a presentation of a proposed novel prototype of a green-energy, water-autonomous greenhouse system. The sophisticated and multi-disciplinary greenhouse system reveals its innovations and advantages by using water resources and solar energy in a rational way, fit for an alternative-technology approach towards sustainable smart-green vertical greening in smart cities. Aimed at improving responsiveness, efficiency and performance for environmental and resource sustainability, and also aimed at improving well-being, the system is expected to be a foresight with simplicity in evolutionary vertical greening. By means of Industry Foundation Classes file format, with a true BIM model consisting of a digital prototype of the physical elements, further design of the system will allow us to simulate an ideal greenhouse type of vertical greening and understand its behavior in both the computer environment and actual on-site construction, as well as allow the building of a smart-green point cloud with BIM workflow on any network in a smart city. © SPSD Press, Kanazawa."
"56315238900;55941133900;57205190043;7401615907;7006111103;35556656200;36836439900;","Concentration and viability of airborne bacteria over the Kuroshio extension region in the northwestern pacific ocean: Data from three cruises",2017,"10.1002/2017JD027287","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042199460&doi=10.1002%2f2017JD027287&partnerID=40&md5=2a6aa4df62d1663ec254d95ddde2a14b","Airborne bacteria have been shown to act as condensation and ice nuclei in mixed-phase clouds and are consequently hypothesized to have significant effects on atmospheric processes and even the global climate. However, few data are available regarding their concentration and variation in the air over the open ocean. Aerosol samples were collected during three cruises in the early summers of 2013, 2014, and 2016 over the Kuroshio Extension region of the northwest Pacific Ocean. The concentrations of viable and nonviable bacterial cells in the marine surface air were quantified using epifluorescence enumeration with the LIVE/DEAD BacLight stain. The concentrations of total bacteria varied between 1.0 × 104 and 2.5 × 105 cells m3 and averaged 5.2 × 104, 1.0 × 105, and 7.5 × 104 cells m3 in the three respective cruises. The viabilities, i.e., the ratios of the concentration of viable bacterial cells to that of total bacterial cells, ranged from 80% to 100% (average 93%), and the respective means were 93%, 89%, and 96% in the cruises. The total bacterial concentration had a close correlation with the wind speed near the sea surface, and the bacterial viability correlated negatively with the air temperature, sea surface temperature, and concentration of coarse particles (size &gt; 1 μm). The deposition and sea spray fluxes of bacteria were roughly estimated as hundreds of cells m2 s1 on average. The limited data on bacterial concentration and viability from the three cruises indicate the rapid air-sea exchange of bacteria over the Kuroshio Extension region of the northwest Pacific Ocean. © 2017. American Geophysical Union. All Rights Reserved."
"56754613500;55705948900;14019100300;55709174800;57191034805;57188699861;7202041928;","Potential impacts of urban land expansion on Asian airborne pollutant outflows",2017,"10.1002/2016JD025564","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85027693481&doi=10.1002%2f2016JD025564&partnerID=40&md5=c25c190dd75de0d6c7f400436fd2a17b","Eastern part of China (EPC) has experienced rapid urbanization during the past few decades. Here we investigate the impacts of urban land expansion over EPC on the export of Asian pollutants to the western Pacific during January, April, July, and October of 2009 using the Weather Research and Forecasting model coupled to Chemistry (WRF/Chem) and a single-layer urban canopy scheme. Over urbanizing areas, increases in the urban land fraction result in a linearly enhanced uplift of surface primary pollutants to higher altitudes. We further examine how this local effect would change outflows of Asian pollutants to the western Pacific using the tagged black carbon (BC) and carbon monoxide (CO) tracers emitted from EPC (denoted by BCt and COt, respectively). Overall, a 0.1 increase in the fraction of land area that is urban over EPC would linearly (R2 = 0.70-0.96) increase the mean tropospheric eastward export of BCt and COt across meridional planes (i.e., 135°E and 150°E) by 4-40% and 1-6% in different months, respectively. The relative perturbation in exporting efficiency generally maximizes during July while minimizes during April. The urbanization-export relationship is largely driven by the elevation effect and is also impacted by urbanization-forced changes in zonal winds. The spatial pattern of the response of BCt over the downwind Pacific differs from that of COt mainly due to aerosol-cloud interactions. Our findings demonstrate that extensive urban land expansion could substantially impact climate and air quality from a local scale to a regional scale, especially for shorter-lived air pollutants such as BC and other aerosols. © 2017. American Geophysical Union. All Rights Reserved."
"57195235059;7102080550;55940931500;57033288300;","Explicit prediction of hail using multimoment microphysics schemes for a hailstorm of 19 march 2014 in eastern China",2017,"10.1002/2017JD026747","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026416749&doi=10.1002%2f2017JD026747&partnerID=40&md5=41d20729ac0766a6ad9efc37a23b03b0","In the late afternoon of 19 March 2014, a severe hailstorm swept through eastern central Zhejiang province, China. The storm produced golf ball-sized hail, strong winds, and lighting, lasting approximately 1 h over the coastal city of Taizhou. The Advanced Regional Prediction System is used to simulate the hailstorm using different configurations of the Milbrandt-Yau microphysics scheme that predict one, two, or three moments of the hydrometeor particle size distribution. Simulated fields, including accumulated precipitation and maximum estimated hail size (MESH), are verified against rain gauge observations and radar-derived MESH, respectively. For the case of the 19 March 2014 storms, the general evolution is better predicted with multimoment microphysics schemes than with the one-moment scheme; the three-moment scheme produces the best forecast. Predictions from the three-moment scheme qualitatively agree with observations in terms of size and amount of hail reaching the surface. The life cycle of the hailstorm is analyzed, using the most skillful, three-moment forecast. Based upon the tendency of surface hail mass flux, the hailstorm life cycle can be divided into three stages: developing, mature, and dissipating. Microphysical budget analyses are used to examine microphysical processes and characteristics during these three stages. The vertical structures within the storm and their link to environmental shear conditions are discussed; together with the rapid fall of hailstones, these structures and conditions appear to dictate this pulse storm’s short life span. Finally, a conceptual model for the life cycle of pulse hailstorms is proposed. © 2017. American Geophysical Union. All Rights Reserved."
"56704589000;7006025236;6604054503;57191610357;56214091200;57193320073;57203776263;6602221672;16834406100;8359591200;56199309500;55659925600;8261329600;15080710300;6506458269;7004346367;6508030754;6701859178;55797926900;55501671800;26643510900;6603775815;6603178707;6603174102;55683899000;16480965400;36616603800;7004643405;57136469800;6603293519;7006027075;6701562043;14048087800;7202558218;56102834700;7006497590;6602356428;7102634471;","Airborne measurements of western U.S. wildfire emissions: Comparison with prescribed burning and air quality implications",2017,"10.1002/2016JD026315","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020704341&doi=10.1002%2f2016JD026315&partnerID=40&md5=6c3e728baf7f4b6d382e4a80b402b192","Wildfires emit significant amounts of pollutants that degrade air quality. Plumes from three wildfires in the western U.S. were measured from aircraft during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) and the Biomass Burning Observation Project (BBOP), both in summer 2013. This study reports an extensive set of emission factors (EFs) for over 80 gases and 5 components of submicron particulate matter (PM1) from these temperate wildfires. These include rarely, or never before, measured oxygenated volatile organic compounds and multifunctional organic nitrates. The observed EFs are compared with previous measurements of temperate wildfires, boreal forest fires, and temperate prescribed fires. The wildfires emitted high amounts of PM1 (with organic aerosol (OA) dominating the mass) with an average EF that is more than 2 times the EFs for prescribed fires. The measured EFs were used to estimate the annual wildfire emissions of carbon monoxide, nitrogen oxides, total nonmethane organic compounds, and PM1 from 11 western U.S. states. The estimated gas emissions are generally comparable with the 2011 National Emissions Inventory (NEI). However, our PM1 emission estimate (1530 ± 570 Gg yr-1) is over 3 times that of the NEI PM2.5 estimate and is also higher thanthe PM2.5 emitted from all other sources in these states in the NEI. This study indicates that the source of OA from biomass burning in the western states is significantly underestimated. In addition, our results indicate that prescribed burning may be an effective method to reduce fine particle emissions. © 2017. American Geophysical Union. All Rights Reserved."
"7404548584;7005420497;7101984634;57203233100;14622650300;36721587000;7004433410;57192810488;7004678728;57203378050;55241984000;7102820305;7005399437;7006783796;6701718281;","Ground-based High Spectral Resolution Lidar observation of aerosol vertical distribution in the summertime Southeast United States",2017,"10.1002/2016JD025798","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014755111&doi=10.1002%2f2016JD025798&partnerID=40&md5=186875a438458fa7572c8c349cffa914","As part of the Southeast United States-based Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS), and collinear with part of the Southeast Atmosphere Study, the University of Wisconsin High Spectral Resolution Lidar system was deployed to the University of Alabama from 19 June to 4 November 2013. With a collocated Aerosol Robotic Network (AERONET) sun photometer, a nearby Chemical Speciation Network (PM2.5) measurement station, and near daily ozonesonde releases for the August-September SEAC4RS campaign, the site allowed the region’s first comprehensive diurnal monitoring of aerosol particle vertical structure. A 532nm lidar ratio of 55 sr provided good closure between aerosol backscatter and AERONET (aerosol optical thickness, AOT). A principle component analysis was performed to identify key modes of variability in aerosol backscatter. “Fair weather” days exhibited classic planetary boundary layer structure of a mixed layer accounting for ~50% of AOT and an entrainment zone providing another 25%. An additional 5-15% of variance is gained from the lower free troposphere from either convective detrainment or frequent intrusions of western United States biomass burning smoke. Generally, aerosol particles were contained below the 0°C level, a common level of stability in convective regimes. However, occasional strong injections of smoke to the upper troposphere were also observed, accounting for the remaining 10-15% variability in AOT. Examples of these common modes of variability in frontal and convective regimes are presented, demonstrating why AOT often has only a weak relationship to surface PM2.5 concentration. © 2017. American Geophysical Union. All Rights Reserved."
"56736859700;7004067078;35935186200;","Forest type classification with combination of advanced polarimetric decompositions and textures of L-band synthetic aperture radar data",2017,"10.1117/1.JRS.11.016035","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014552359&doi=10.1117%2f1.JRS.11.016035&partnerID=40&md5=60e5c9b0960293e7c4415b570f6fabf9","Information on distribution of forest types and land cover classes is essential for decision making and significant in climate regulation, biodiversity conservation, and societal issues. An approach for the combination of advanced polarimetric decompositions and textures of Advanced Land Observing Satellite Phased Array L-band Synthetic Aperture Radar full polarimetric data for the purpose of forest type classification is proposed. Using a support vector machine (SVM) classifier, we classified forest types over a selected Indian region. Further, we tested the classification performance of the Wishart method for the same forest types. The classified results were assessed with confusion matrix-based statistics. The results suggest that incorporation of various polarimetric decompositions features into gray-level co-occurrence matrix textures refines the SVM classification overall accuracy (OA) from 73.82% (k=0.69) to 76.34% (k=0.72). The Wishart supervised classification algorithm has the OA of 73.38% (kappa=0.68). We observed that integration of polarimetric information with textures can give complimentary information in forest type discrimination and produce high accuracy maps. Further, this approach overcomes the limitations of optical remote sensing data in continuous cloud coverage areas. © 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)."
"54782721600;56463161500;56152346800;57193004647;","MODIS 3 km and 10 km aerosol optical depth for China: Evaluation and comparison",2017,"10.1016/j.atmosenv.2017.01.023","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009948890&doi=10.1016%2fj.atmosenv.2017.01.023&partnerID=40&md5=51896201b4e236bfe8d1766484e83cf4","The recently released Moderate Resolution Imaging Spectrometer (MODIS) Collection 6 introduced a fine scale aerosol optical depth (AOD) distribution, the 3 km product, which is expected to perform well in analyzing aerosols and identifying local air pollution, especially in the severely polluted atmosphere of China. However, few detailed evaluations of regional variations have been conducted. In this paper, we evaluate MODIS 3 km and 10 km AOD products for China against ground-based measurements and compare their performance with respect to spatial and temporal variations. The ground validations indicate that the two products are generally correlated well to ground-based observations. Spatially, the 3 km product slightly outperform the 10 km product in well-developed areas of southern China. Temporally, both products perform worse during spring and summer. Atmospheric clouds and underlying surface are two key factors that influence the accuracy and number of retrievals for both products. The comparison analysis reveals the newly introduced AOD product clearly shows good relationships with the coarse resolution retrievals in spatial and temporal variation but significant differences regarding details. The 3 km AOD product provides better aerosol gradients, more retrievals in bare areas of western China and some spikes of diurnal variation in cloudy days. Seasonal comparisons show the 3 km AOD product is higher than the 10 km product in all seasons, especially during spring and summer. Although the 3 km product for China generally performs slightly worse than the 10 km product, the added information of the MODIS 3 km AOD product shows potential for studying local aerosol characterization, and may facilitate studies of air pollution. © 2017 Elsevier Ltd"
"57195958231;8211380400;","Influence of the West Pacific subtropical high on surface ozone daily variability in summertime over eastern China",2017,"10.1016/j.atmosenv.2017.09.024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030460162&doi=10.1016%2fj.atmosenv.2017.09.024&partnerID=40&md5=b8582b734569eb6a1782d37388604cc7","The West Pacific subtropical high (WPSH), as one of the most important components of the East Asian summer monsoon (EASM), is the key synoptic-scale circulation pattern influencing summertime precipitation and atmospheric conditions in China. Here we investigate the impacts of the WPSH on surface ozone daily variability over eastern China, using observations from recently established network of ozone monitors and meteorology reanalysis data during summer (June, July, August; JJA) 2014–2016 with a focus on 2014. An empirical orthogonal function (EOF) analysis of daily ozone variations reveals that the dominating eigenvector (EOF1), which contributes a quarter (25.2%) to the total variances, is a marked north-south contrast. This pattern is temporally well correlated (r = −0.66, p < 0.01) with daily anomalies of a normalized WPSH intensity index (WPSH-I). Spatially, the WPSH-I and ozone correlation is positive in North China (NC) but negative in South China (SC), which well correlates with the ozone EOF1 pattern showing the same north-south contrast (r = −0.86, p < 0.01). These associations suggest the dominant component of surface ozone daily variability in eastern China is linked with the variability of the WPSH intensity in that a stronger WPSH leads to a decrease of surface ozone over SC but an increase over NC and vice versa. This is because a stronger WPSH enhances southwesterly transport of moisture into SC, creating such conditions not conducive for ozone formation as higher RH, more cloudiness and precipitation, less UV radiation, and lower temperature. Meanwhile, as most of the rainfall due to the enhanced southwesterly transport of moisture occurs in SC, water vapor is largely depleted in the air masses transported towards NC, creating dry and sunny conditions over NC under a strong WPSH, thereby promoting ozone formation. © 2017 Elsevier Ltd"
"7202748891;55999844600;57198110897;36061813500;6602321641;57196612094;22234792700;55887377500;6603816055;35268331200;7404495164;7402971417;35495958000;","The future of Earth observation in hydrology",2017,"10.5194/hess-21-3879-2017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019592216&doi=10.5194%2fhess-21-3879-2017&partnerID=40&md5=a397a6d626e3ef432b06bba138890fa0","In just the past 5 years, the field of Earth observation has progressed beyond the offerings of conventional space-agency-based platforms to include a plethora of sensing opportunities afforded by CubeSats, unmanned aerial vehicles (UAVs), and smartphone technologies that are being embraced by both for-profit companies and individual researchers. Over the previous decades, space agency efforts have brought forth well-known and immensely useful satellites such as the Landsat series and the Gravity Research and Climate Experiment (GRACE) system, with costs typically of the order of 1 billion dollars per satellite and with concept-to-launch timelines of the order of 2 decades (for new missions). More recently, the proliferation of smartphones has helped to miniaturize sensors and energy requirements, facilitating advances in the use of CubeSats that can be launched by the dozens, while providing ultra-high (3- 5 m) resolution sensing of the Earth on a daily basis. Startup companies that did not exist a decade ago now operate more satellites in orbit than any space agency, and at costs that are a mere fraction of traditional satellite missions. With these advances come new space-borne measurements, such as real-time high-definition video for tracking air pollution, storm-cell development, flood propagation, precipitation monitoring, or even for constructing digital surfaces using structure-from-motion techniques. Closer to the surface, measurements from small unmanned drones and tethered balloons have mapped snow depths, floods, and estimated evaporation at sub-metre resolutions, pushing back on spatio-temporal constraints and delivering new process insights. At ground level, precipitation has been measured using signal attenuation between antennae mounted on cell phone towers, while the proliferation of mobile devices has enabled citizen scientists to catalogue photos of environmental conditions, estimate daily average temperatures from battery state, and sense other hydrologically important variables such as channel depths using commercially available wireless devices. Global internet access is being pursued via highaltitude balloons, solar planes, and hundreds of planned satellite launches, providing a means to exploit the ""internet of things"" as an entirely new measurement domain. Such global access will enable real-time collection of data from billions of smartphones or from remote research platforms. This future will produce petabytes of data that can only be accessed via cloud storage and will require new analytical approaches to interpret. The extent to which today's hydrologic models can usefully ingest such massive data volumes is unclear. Nor is it clear whether this deluge of data will be usefully exploited, either because the measurements are superfluous, inconsistent, not accurate enough, or simply because we lack the capacity to process and analyse them. What is apparent is that the tools and techniques afforded by this array of novel and game-changing sensing platforms present our community with a unique opportunity to develop new insights that advance fundamental aspects of the hydrological sciences. To accomplish this will require more than just an application of the technology: in some cases, it will demand a radical rethink on how we utilize and exploit these new observing systems. © Author(s) 2017."
"57191410502;7102350138;7005322937;","Knowing but not knowing: Systematic conservation planning and community conservation in the Sierra Norte of Oaxaca, Mexico",2016,"10.1016/j.landusepol.2016.09.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989853906&doi=10.1016%2fj.landusepol.2016.09.010&partnerID=40&md5=e2e604dc14a9f132f237d519a73fcd99","Systematic conservation planning (SCP) seeks to propose new reserves through a scientifically rigorous process using databases and research selection algorithims. However, SCP exercises have been criticized for “knowing but not doing”, i.e. not implementing the proposed reserve. But there is an additional problem that can be called “knowing but not knowing”, knowing things from databases, but not knowing crucial contextual information about community-based social processes that have supported the high forest cover and biodiversity detected. Examined here is how a common property region of the Sierra Norte of Oaxaca, Mexico has maintained high forest cover in the absence of public protected areas, while multiple SCP exercises have advocated for the creation of public protected areas in communal tropical montane cloud forests and pine forests as strategies for biodiversity conservation and resilience to climate change. Methods included archival research, review of community documents, focus group interviews, semi-structured interviews, participant observation, land use transects, and GIS analysis and remote sensing. Conservation in the region originally occurred because of low population densities, steep slopes and a lack of agricultural subsidies, supported by locally adapted agricultural practices. In the 1990s, a transition from passive to active conservation took place with land use zoning plans, community conservation rules, community forestry enterprises and payments for environmental service programs that consolidated a trend towards high, unthreatened forest cover. Today, the study communities have an average of 88.3% forest cover, with 61% of that in informal conservation based on community land use zoning and rules and another 14% governed by forest management plans approved by the Mexican government. We argue that truly systematic conservation plans would seek to understand how communities in the region are already managing forests for conservation. It is pointless and uninformed to advocate for top-down conservation interventions of forests that are already robustly conserved and resilient to climate change due to community action. © 2016 Elsevier Ltd"
"35302065900;26538561700;7005975931;","Dust-infused baroclinic cyclone storm clouds: The evidence, meteorology, and some implications",2016,"10.1002/2016GL071801","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007439480&doi=10.1002%2f2016GL071801&partnerID=40&md5=daf503c306529e7b1b127354e92a8fd0","Desert mineral dust is a critical yet still poorly understood component of atmospheric composition, weather, and climate. Long-range transport of dust is well known, yet uncertainty persists regarding the pathway from the desert floor to the free troposphere. Here we will show that a recurrent pathway for dust into the uppermost troposphere involves passage through an extratropical baroclinic cyclonic storm. The evidence derives from a synergistic use of satellite-based, multispectral nadir-image data and lidar. The dust-infused baroclinic storm (DIBS) exhibits peculiar cirrus cloud top reflected and emitted radiance from the UV through thermal IR, involving positive UV absorbing aerosol index, muted visible reflectivity, visible cumuliform texture, and systematically intense visible lidar backscatter on a synoptic scale. Proof that the DIBS is microphysically impacted by storm-scale dust infusion is the occurrence of anomalously large daytime 3.9–11μm brightness temperature difference indicative of small ice crystals. We present multispectral snapshots of two DIBS, over two desert source regions, in comparison with a pristine baroclinic storm cloud. Each storm snapshot is presented in the context of the baroclinic cyclone's lifetime and dust source region (the Gobi desert and the Sahara). These and other cases discussed show that the DIBS is a recurring conduit for long-range transport and a natural experiment in dust-related aerosol indirect effects. ©2016. American Geophysical Union. All Rights Reserved."
"35069282600;57044397100;7202899330;","Aerosol indirect effect dictated by liquid clouds",2016,"10.1002/2016JD025245","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007404014&doi=10.1002%2f2016JD025245&partnerID=40&md5=e5d71edc085f9384458f17811d9db18e","Anthropogenic aerosols have been shown to enhance the solar reflection from warm liquid clouds and mask part of the warming due to the buildup of greenhouse gases. However, very little is known about the effects of aerosol on mixed-phase stratiform clouds as well as other cloud regimes including cumulus, altocumulus, nimbostratus, deep convection, and anvil cirrus. These additional cloud categories are ubiquitous and typically overlooked in satellite-based assessments of the global aerosol indirect forcing. Here we provide their contribution to the aerosol indirect forcing estimate using satellite data collected from several colocated sensors in the A-train for the period 2006-2010. Cloud type is determined according to the 2B-CLDCLASS-LIDAR CloudSat product, and the observations are matched to the radiative flux measurements from CERES (Clouds and the Earth’s Radiant Energy System) and aerosol retrievals from MODIS (MODerate resolution Imaging Spectroradiometer). The oceanic mean aerosol indirect forcing is estimated to be -0.20 ± 0.31Wm-2 with warm low-level cloud largely dictating the strength of the response (-0.36 ± 0.21Wm-2) due to their abundance and strong cloud albedo effect. Contributions from mixed-phase low-level cloud (0.01 ± 0.06Wm-2) and convective cloud (0.15 ± 0.23Wm-2) are positive and buffer the system due to strong aerosol-cloud feedbacks that reduce the cloud albedo effect and/or lead to convective invigoration causing a countering positive longwave warming response. By combining all major cloud categories together, aerosol indirect forcing decreases and now contains positive values in the uncertainty estimate. © 2016. American Geophysical Union. All Rights Reserved."
"57192649053;25928285500;6603196991;7402934750;","Statistical retrieval of thin liquid cloud microphysical properties using ground-based infrared andmicrowave observations",2016,"10.1002/2016JD025667","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007042174&doi=10.1002%2f2016JD025667&partnerID=40&md5=9c106e24acceda10190fa87a32e155fe","In this article, liquid water cloud microphysical properties are retrieved by a combination of microwave and infrared ground-based observations. Clouds containing liquid water are frequently occurring in most climate regimes and play a significant role in terms of interaction with radiation. Small perturbations in the amount of liquid water contained in the cloud can cause large variations in the radiative fluxes. This effect is enhanced for thin clouds (liquid water path, LWP&lt;100 g/m2), which makes accurate retrieval information of the cloud properties crucial. Due to large relative errors in retrieving low LWP values from observations in the microwave domain and a high sensitivity for infrared methods when the LWP is low, a synergistic retrieval based on a neural network approach is built to estimate both LWP and cloud effective radius (reff). These statistical retrievals can be applied without high computational demand but imply constraints like prior information on cloud phase and cloud layering. The neural network retrievals are able to retrieve LWP and reff for thin clouds with a mean relative error of 9% and 17%, respectively. This is demonstrated using synthetic observations of a microwave radiometer (MWR) and a spectrally highly resolved infrared interferometer. The accuracy and robustness of the synergistic retrievals is confirmed by a low bias in a radiative closure study for the downwelling shortwave flux, even for marginally invalid scenes. Also, broadband infrared radiance observations, in combination with the MWR, have the potential to retrieve LWP with a higher accuracy than a MWR-only retrieval. © 2016. American Geophysical Union. All Rights Reserved."
"56158229700;24833810000;7102062952;7004176333;38762392200;6603445661;24168241000;7004040199;56396678200;7006372688;7103313796;12782225200;6602252175;6701378450;57192868410;7403063262;57192868752;","Isoprene suppression of new particle formation: Potential mechanisms and implications",2016,"10.1002/2016JD024844","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008516023&doi=10.1002%2f2016JD024844&partnerID=40&md5=0cb97dc34efa8c4ff60058bb8906bde3","Secondary aerosols formed from anthropogenic pollutants and natural emissions have substantial impacts on human health, air quality, and the Earth’s climate. New particle formation (NPF) contributes up to 70% of the global production of cloud condensation nuclei (CCN), but the effects of biogenic volatile organic compounds (BVOCs) and their oxidation products on NPF processes in forests are poorly understood. Observations show that isoprene, the most abundant BVOC, suppresses NPF in forests. But the previously proposed chemical mechanism underlying this suppression process contradicts atmospheric observations. By reviewing observations made in other forests, it is clear that NPF rarely takes place during the summer when emissions of isoprene are high, even though there are sufficient concentrations of monoterpenes. But at present it is not clear how isoprene and its oxidation products may change the oxidation chemistry of terpenes and how NOx and other atmospheric key species affect NPF in forest environments. Future laboratory experiments with chemical speciation of gas phase nucleation precursors and clusters and chemical composition of particles smaller than 10nm are required to understand the role of isoprene in NPF. Our results show that climate models can overpredict aerosol’s first indirect effect when not considering the absence of NPF in the southeastern U.S. forests during the summer using the current nucleation algorithm that includes only sulfuric acid and total concentrations of low-volatility organic compounds. This highlights the importance of understanding NPF processes as function of temperature, relative humidity, and BVOC compositions to make valid predictions of NPF and CCN at a wide range of atmospheric conditions. © 2016. American Geophysical Union. All Rights Reserved."
"57192392272;15519804100;24079567500;","The intraannual variability of land-atmosphere coupling over North America in the Canadian Regional Climate Model (CRCM5)",2016,"10.1002/2016JD025423","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006100979&doi=10.1002%2f2016JD025423&partnerID=40&md5=c053214cd7315687f7d101605b22c373","This study investigates the intraannual variability of soil moisture-temperature coupling over North America. To this effect, coupled and uncoupled simulations are performed with the fifth-generation Canadian Regional Climate Model (CRCM5), driven by ERA-Interim. In coupled simulations, land and atmosphere interact freely; in uncoupled simulations, the interannual variability of soil moisture is suppressed by prescribing climatological values for soil liquid and frozen water contents. The study also explores projected changes to coupling by comparing coupled and uncoupled CRCM5 simulations for current (1981-2010) and future (2071-2100) periods, driven by the Canadian Earth System Model. Coupling differs for the northern and southern parts of North America. Over the southern half, it is persistent throughout the year while for the northern half, strongly coupled regions generally follow the freezing line during the cold months. Detailed analysis of the southern Canadian Prairies reveals seasonal differences in the underlying coupling mechanism. During spring and fall, as opposed to summer, the interactive soil moisture phase impacts the snow depth and surface albedo, which further impacts the surface energy budget and thus the surface air temperature; the air temperature then influences the snow depth in a feedback loop. Projected changes to coupling are also season specific: relatively drier soil conditions strengthen coupling during summer, while changes in soil moisture phase, snow depth, and cloud cover impact coupling during colder months. Furthermore, results demonstrate that soil moisture variability amplifies the frequency of temperature extremes over regions of strong coupling in current and future climates. © 2016. The Authors."
"57204308417;57198900588;26429409700;7409077047;","Preliminary validation of two temporal parameter-based soil moisture retrieval models using a satellite product and in situ soil moisture measurements over the REMEDHUS network",2016,"10.1080/01431161.2016.1253896","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84997316678&doi=10.1080%2f01431161.2016.1253896&partnerID=40&md5=29f037d461088e7225cb64761f835335","This study aims to preliminarily validate two newly developed temporal parameter-based surface soil moisture (SSM) retrieval models, namely the mid-morning model and daytime model, using both microwave satellite soil moisture product and in situ SSM measurements over a well-organized soil moisture network named REd de MEDición de la HUmedad del Suelo (REMEDHUS) in Spain. Ground SSM measurements and geostationary satellite observations were primarily implemented to obtain the model coefficients for the two SSM retrieval models for each cloud-free day. These model coefficients were subsequently used to estimate SSM using the Meteosat Second Generation products over the study area. Preliminary verification using both a satellite product and in situ SSM measurements demonstrated that SSM variation can be well detected by both SSM retrieval models. Specifically, a generally similar accuracy (coefficient of determination R2: 0.419–0.379, root mean square error: 0.046–0.051 m3 m−3, Bias: −0.020 to −0.025 m3 m−3) was found for the mid-morning model and the daytime model with the microwave missions based climate change initiative SSM product, respectively. Moreover, except for the comparable R2 (0.614–0.675), a better accuracy (Bias: 0.032–0.044 m3 m−3, RMSE: 0.043–0.050 m3 m−3) are achieved for the daytime model and the mid-morning model with network SSM measurements, respectively. These results indicate that the daytime model exhibited generally comparable or better accuracy than that of the mid-morning model over the study area. This study has strengthened the feasibility of using multi-temporal information derived from the geostationary satellites to estimate SSM in future research. © 2016 Informa UK Limited, trading as Taylor & Francis Group."
"24757981500;57193840197;6506383700;57217352376;6604005739;6507979420;6603265463;7404661626;8696316000;57192174561;57190986853;56225488500;55613373200;6506180220;6603684021;36047973900;","Tethered balloon-born and ground-based measurements of black carbon and particulate profiles within the lower troposphere during the foggy period in Delhi, India",2016,"10.1016/j.scitotenv.2016.08.185","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84985014402&doi=10.1016%2fj.scitotenv.2016.08.185&partnerID=40&md5=8fc7634105f7fafcd9e424b618b88ea3","The ground and vertical profiles of particulate matter (PM) were mapped as part of a pilot study using a Tethered balloon within the lower troposphere (1000 m) during the foggy episodes in the winter season of 2015–16 in New Delhi, India. Measurements of black carbon (BC) aerosol and PM &lt; 2.5 and 10 μm (PM2.5 &amp; PM10 respectively) concentrations and their associated particulate optical properties along with meteorological parameters were made. The mean concentrations of PM2.5, PM10, BC370 nm, and BC880 nm were observed to be 146.8 ± 42.1, 245.4 ± 65.4, 30.3 ± 12.2, and 24.1 ± 10.3 μg m− 3, respectively. The mean value of PM2.5 was ~ 12 times higher than the annual US-EPA air quality standard. The fraction of BC in PM2.5 that contributed to absorption in the shorter visible wavelengths (BC370 nm) was ~ 21%. Compared to clear days, the ground level mass concentrations of PM2.5 and BC370 nm particles were substantially increased (59% and 24%, respectively) during the foggy episode. The aerosol light extinction coefficient (σext) value was much higher (mean: 610 Mm− 1) during the lower visibility (foggy) condition. Higher concentrations of PM2.5 (89 μg m− 3) and longer visible wavelength absorbing BC880 nm (25.7 μg m− 3) particles were observed up to 200 m. The BC880 nm and PM2.5 aerosol concentrations near boundary layer (1 km) were significantly higher (~ 1.9 and 12 μg m− 3), respectively. The BC (i.e BCtot) aerosol direct radiative forcing (DRF) values were estimated at the top of the atmosphere (TOA), surface (SFC), and atmosphere (ATM) and its resultant forcing were - 75.5 Wm− 2 at SFC indicating the cooling effect at the surface. A positive value (20.9 Wm− 2) of BC aerosol DRF at TOA indicated the warming effect at the top of the atmosphere over the study region. The net DRF value due to BC aerosol was positive (96.4 Wm− 2) indicating a net warming effect in the atmosphere. The contribution of fossil and biomass fuels to the observed BC aerosol DRF values was ~ 78% and ~ 22%, respectively. The higher mean atmospheric heating rate (2.71 K day− 1) by BC aerosol in the winter season would probably strengthen the temperature inversion leading to poor dispersion and affecting the formation of clouds. Serious detrimental impacts on regional climate due to the high concentrations of BC and PM (especially PM2.5) aerosol are likely based on this study and suggest the need for immediate, stringent measures to improve the regional air quality in the northern India. © 2016 Elsevier B.V."
"24337553400;56158622800;7005399437;57192423530;","Comparison of key absorption and optical properties between pure and transported anthropogenic dust over East and Central Asia",2016,"10.5194/acp-16-15501-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006340188&doi=10.5194%2facp-16-15501-2016&partnerID=40&md5=a8970d95a9378d8c9daf230f255c65bc","Asian dust particulate is one of the primary aerosol constituents in the Earth-atmosphere system that exerts profound influences on environmental quality, human health, the marine biogeochemical cycle, and Earth's climate. To date, the absorptive capacity of dust aerosol generated from the Asian desert region is still an open question. In this article, we compile columnar key absorption and optical properties of mineral dust over East and Central Asian areas by utilizing the multiyear quality-assured datasets observed at 13 sites of the Aerosol Robotic Network (AERONET). We identify two types of Asian dust according to threshold criteria from previously published literature. (1) The particles with high aerosol optical depth at 440g nm (AOD440 ≥ g 0.4) and a low Ångström wavelength exponent at 440-870g nm (<i>α</i>g &lt;g 0.2) are defined as Pure Dust (PDU), which decreases disturbance of other non-dust aerosols and keeps high accuracy of pure Asian dust. (2) The particles with AOD440 ≥ g 0.4 and 0.2g &lt;g <i>α</i>g &lt;g 0.6 are designated as Transported Anthropogenic Dust (TDU), which is mainly dominated by dust aerosol and might mix with other anthropogenic aerosol types. Our results reveal that the primary components of high AOD days are predominantly dust over East and Central Asian regions, even if their variations rely on different sources, distance from the source, emission mechanisms, and meteorological characteristics. The overall mean and standard deviation of single-scattering albedo, asymmetry factor, real part and imaginary part of complex refractive index at 550g nm for Asian PDU are 0.935g ±g 0.014, 0.742g ±g 0.008, 1.526g ±g 0.029, and 0.00226g ±g 0.00056, respectively, while corresponding values are 0.921g ±g 0.021, 0.723g ±g 0.009, 1.521g ±g 0.025, and 0.00364g ±g 0.0014 for Asian TDU. Aerosol shortwave direct radiative effects at the top of the atmosphere (TOA), at the surface (SFC), and in the atmospheric layer (ATM) for Asian PDU (<i>α</i>g &lt;g 0.2) and TDU (0.2g &lt;g <i>α</i>g &lt;g 0.6) computed in this study, are a factor of 2 smaller than the results of Optical Properties of Aerosols and Clouds (OPAC) mineral-accumulated (mineral-acc.) and mineral-transported (mineral-tran.) modes. Therefore, we are convinced that our results hold promise for updating and improving accuracies of Asian dust characteristics in present-day remote sensing applications and regional or global climate models. © Author(s) 2016. CC Attribution 3.0 License."
"55368857800;15834571900;7006145109;6603400565;","On the performance of remote sensing time series reconstruction methods – A spatial comparison",2016,"10.1016/j.rse.2016.10.025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994275217&doi=10.1016%2fj.rse.2016.10.025&partnerID=40&md5=eb57b46e44db1fcd6e842be9aa208b87","The satellite observed Normalized Difference Vegetation Index (NDVI) time series, which describe the temporal and spatial variability of global terrestrial vegetation, are inevitably contaminated by clouds, aerosol, snow and ice cover. In general all these conditions yield negative deviations in the time series of NDVI. Many time series reconstruction models have been developed to eliminate effect of the negative deviations and most of them perform differently in different applications and regions. The Harmonic Analysis (HA), Double logistic (DL), Asymmetric Gaussian (AG), Whittaker smoother (WS) and Savitzky–Golay filter (SG) are five of the most widely used time series reconstruction models owing to their simplicity of implementation or the capability to extract phenological metrics from the time series. The performance of these models varies with the NDVI signal and the noise distribution, however, and until now there is no consensus on which method outperforms all others under all situations. Since the NDVI signal and the noise distribution are highly dependent on regional climate and land cover, the reconstruction performance is expected to be spatially variable. Thus this study compared the five reconstruction models at pixel scale to provide practical and biome – specific recommendations for future time series reconstruction applications. Specifically, the 14 years raw daily reflectance data and ancillary Quality Assessment (QA) information from the MODIS sensor were used to generate pixel reference series and noisy series. Then the five candidate models were applied to both reference series and noisy series and three reconstruction performance metrics i.e. Overall Reconstruction Error (ORE), Fitting Related Error (FRE), and Normalized Noise Related Error (NNRE), were calculated. Finally, the performance of the five candidate reconstruction models was evaluated by applying the three metrics. The preliminary results showed that when considering ORE only, the Asymmetric Gaussian model outperforms other models over most areas of high latitude boreal region, while the Savitzky–Golay model gives the best reconstruction performance in tropical and subtropical regions. The FRE and the NNRE helped to reveal the main error sources in the reconstruction in different regions. The comparison method developed and applied in this study led to suggest adaptive selection of the best reconstruction model for specific NDVI signals and noise distribution. © 2016 Elsevier Inc."
"16645127300;8953038700;","Deriving clear-sky longwave spectral flux from spaceborne hyperspectral radiance measurements: A case study with AIRS observations",2016,"10.5194/amt-9-6013-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006355242&doi=10.5194%2famt-9-6013-2016&partnerID=40&md5=2258091be325686262c5ecf63b3199af","Previous studies have shown that longwave (LW) spectral fluxes have unique merit in climate studies. Using Atmospheric Infrared Sounder (AIRS) radiances as a case study, this study presents an algorithm to derive the entire LW clear-sky spectral fluxes from spaceborne hyperspectral observations. No other auxiliary observations are needed in the algorithm. A clear-sky scene is identified using a three-step detection method. The identified clear-sky scenes are then categorized into different sub-scene types using information about precipitable water, lapse rate and surface temperature inferred from the AIRS radiances at six selected channels. A previously established algorithm is then used to invert AIRS radiances to spectral fluxes over the entire LW spectrum at 10g cmg'1 spectral interval. Accuracy of the algorithms is evaluated against collocated Clouds and the Earth's Radiant Energy System (CERES) observations. For nadir-view observations, the mean difference between outgoing longwave radiation (OLR) derived by this algorithm and the collocated CERES OLR is 1.52g Wmg'2 with a standard deviation of 2.46g Wmg'2. When the algorithm is extended for viewing zenith angle up to 45°, the performance is comparable to that for nadir-view results. © Author(s) 2016. CC Attribution 3.0 License."
"56502199700;8067118800;30767858100;7202079615;","The source of discrepancies in aerosol-cloud-precipitation interactions between GCM and A-Train retrievals",2016,"10.5194/acp-16-15413-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006321444&doi=10.5194%2facp-16-15413-2016&partnerID=40&md5=0bbdfbc1102f2edc3d871fca633473c6","Aerosol-cloud interactions are one of the most uncertain processes in climate models due to their nonlinear complexity. A key complexity arises from the possibility that clouds can respond to perturbed aerosols in two opposite ways, as characterized by the traditional ""cloud lifetime"" hypothesis and more recent ""buffered system"" hypothesis. Their importance in climate simulations remains poorly understood. Here we investigate the response of the liquid water path (LWP) to aerosol perturbations for warm clouds from the perspective of general circulation model (GCM) and A-Train remote sensing, through process-oriented model evaluations. A systematic difference is found in the LWP response between the model results and observations. The model results indicate a near-global uniform increase of LWP with increasing aerosol loading, while the sign of the response of the LWP from the A-Train varies from region to region. The satellite-observed response of the LWP is closely related to meteorological and/or macrophysical factors, in addition to the microphysics. The model does not reproduce this variability of cloud susceptibility (i.e., sensitivity of LWP to perturbed aerosols) because the parameterization of the autoconversion process assumes only suppression of rain formation in response to increased cloud droplet number, and does not consider macrophysical aspects that serve as a mechanism for the negative responses of the LWP via enhancements of evaporation and precipitation. Model biases are also found in the precipitation microphysics, which suggests that the model generates rainwater readily even when little cloud water is present. This essentially causes projections of unrealistically frequent and light rain, with high cloud susceptibilities to aerosol perturbations. © Author(s) 2016."
"57192302181;18133904700;55708686800;16403862600;7003412405;7102020573;7006993483;","What are the greenhouse gas observing system requirements for reducing fundamental biogeochemical process uncertainty? Amazon wetland CH4 emissions as a case study",2016,"10.5194/acp-16-15199-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003486105&doi=10.5194%2facp-16-15199-2016&partnerID=40&md5=4579056f1398b8b398202ceb3ccf2268","Understanding the processes controlling terrestrial carbon fluxes is one of the grand challenges of climate science. Carbon cycle process controls are readily studied at local scales, but integrating local knowledge across extremely heterogeneous biota, landforms and climate space has proven to be extraordinarily challenging. Consequently, top-down or integral flux constraints at process-relevant scales are essential to reducing process uncertainty. Future satellite-based estimates of greenhouse gas fluxes-such as CO2 and CH4-could potentially provide the constraints needed to resolve biogeochemical process controls at the required scales. Our analysis is focused on Amazon wetland CH4 emissions, which amount to a scientifically crucial and methodologically challenging case study.We quantitatively derive the observing system (OS) requirements for testing wetland CH4 emission hypotheses at a process-relevant scale. To distinguish between hypothesized hydrological and carbon controls on Amazon wetland CH4 production, a satellite mission will need to resolve monthly CH4 fluxes at a ∑333 km resolution and with a ≤10 mgCH4 m-2 day-1 flux precision.We simulate a range of low-earth orbit (LEO) and geostationary orbit (GEO) CH4 OS configurations to evaluate the ability of these approaches to meet the CH4 flux requirements. Conventional LEO and GEO missions resolve monthly ∼333 km Amazon wetland fluxes at a 17.0 and 2.7 mgCH4 m-2 day-1 median uncertainty level. Improving LEO CH4 measurement precision by 2 would only reduce the median CH4 flux uncertainty to 11.9 mgCH4 m-2 day-1. A GEO mission with targeted observing capability could resolve fluxes at a 2.0-2.4 mgCH4 m-2 day-1 median precision by increasing the observation density in high cloud-cover regions at the expense of other parts of the domain. We find that residual CH4 concentration biases can potentially reduce the ∼5-fold flux CH4 precision advantage of a GEO mission to a ∼2-fold advantage (relative to a LEO mission). For residual CH4 bias correlation lengths of 100 km, the GEO can nonetheless meet the ≤10 mg CH4 m-2 day-1 requirements for systematic biases ≤10 ppb. Our study demonstrates that processdriven greenhouse gas OS simulations can enhance conventional uncertainty reduction assessments by quantifying the OS characteristics required for testing biogeochemical process hypotheses. © 2016 Author(s)."
"8882641700;7004479957;8977001000;55272477500;24173130300;7005056279;56033466400;","CGILS Phase 2 LES intercomparison of response of subtropical marine low cloud regimes to CO2 quadrupling and a CMIP3 composite forcing change",2016,"10.1002/2016MS000765","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995968692&doi=10.1002%2f2016MS000765&partnerID=40&md5=d6a07a25d45cd216d6a2a3a76ef329e3","Phase 1 of the CGILS large-eddy simulation (LES) intercomparison is extended to understand if subtropical marine boundary-layer clouds respond to idealized climate perturbations consistently in six LES models. Here the responses to quadrupled carbon dioxide (“fast adjustment”) and to a composite climate perturbation representative of CMIP3 multimodel mean 2×CO2 near-equilibrium conditions are analyzed. As in Phase 1, the LES is run to equilibrium using specified steady summertime forcings representative of three locations in the Northeast Pacific Ocean in shallow well-mixed stratocumulus, decoupled stratocumulus, and shallow cumulus cloud regimes. The results are generally consistent with a single-LES study of Bretherton et al. () on which this intercomparison was based. Both quadrupled CO2 and the composite climate perturbation result in less cloud and a shallower boundary layer for all models in well-mixed stratocumulus and for all but a single LES in decoupled stratocumulus and shallow cumulus, corroborating similar findings from global climate models (GCMs). For both perturbations, the amount of cloud reduction varies across the models, but there is less intermodel scatter than in GCMs. The cloud radiative effect changes are much larger in the stratocumulus-capped regimes than in the shallow cumulus regime, for which precipitation buffering may damp the cloud response. In the decoupled stratocumulus and cumulus regimes, both the CO2 increase and CMIP3 perturbations reduce boundary-layer decoupling, due to the shallowing of inversion height. © 2016. The Authors."
"55332348600;26645289600;7402064802;","Impact of decadal cloud variations on the Earth's energy budget",2016,"10.1038/ngeo2828","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85001086925&doi=10.1038%2fngeo2828&partnerID=40&md5=8466cc3c3672bd6b4820620164c792b5","Feedbacks of clouds on climate change strongly influence the magnitude of global warming. Cloud feedbacks, in turn, depend on the spatial patterns of surface warming, which vary on decadal timescales. Therefore, the magnitude of the decadal cloud feedback could deviate from the long-term cloud feedback. Here we present climate model simulations to show that the global mean cloud feedback in response to decadal temperature fluctuations varies dramatically due to time variations in the spatial pattern of sea surface temperature. We find that cloud anomalies associated with these patterns significantly modify the Earth's energy budget. Specifically, the decadal cloud feedback between the 1980s and 2000s is substantially more negative than the long-term cloud feedback. This is a result of cooling in tropical regions where air descends, relative to warming in tropical ascent regions, which strengthens low-level atmospheric stability. Under these conditions, low-level cloud cover and its reflection of solar radiation increase, despite an increase in global mean surface temperature. These results suggest that sea surface temperature pattern-induced low cloud anomalies could have contributed to the period of reduced warming between 1998 and 2013, and offer a physical explanation of why climate sensitivities estimated from recently observed trends are probably biased low."
"49664027700;35509639400;7004714030;36187387300;","Coupling between lower-tropospheric convective mixing and low-level clouds: Physical mechanisms and dependence on convection scheme",2016,"10.1002/2016MS000740","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006810877&doi=10.1002%2f2016MS000740&partnerID=40&md5=a20be38c148f3d09842c4df9633d7141","Several studies have pointed out the dependence of low-cloud feedbacks on the strength of the lower-tropospheric convective mixing. By analyzing a series of single-column model experiments run by a climate model using two different convective parametrizations, this study elucidates the physical mechanisms through which marine boundary-layer clouds depend on this mixing in the present-day climate and under surface warming. An increased lower-tropospheric convective mixing leads to a reduction of low-cloud fraction. However, the rate of decrease strongly depends on how the surface latent heat flux couples to the convective mixing and to boundary-layer cloud radiative effects: (i) on the one hand, the latent heat flux is enhanced by the lower-tropospheric drying induced by the convective mixing, which damps the reduction of the low-cloud fraction, (ii) on the other hand, the latent heat flux is reduced as the lower troposphere stabilizes under the effect of reduced low-cloud radiative cooling, which enhances the reduction of the low-cloud fraction. The relative importance of these two different processes depends on the closure of the convective parameterization. The convective scheme that favors the coupling between latent heat flux and low-cloud radiative cooling exhibits a stronger sensitivity of low-clouds to convective mixing in the present-day climate, and a stronger low-cloud feedback in response to surface warming. In this model, the low-cloud feedback is stronger when the present-day convective mixing is weaker and when present-day clouds are shallower and more radiatively active. The implications of these insights for constraining the strength of low-cloud feedbacks observationally is discussed. © 2016. The Authors."
"56909327200;7401836526;36097134700;55351266200;","Large-eddy simulation of subtropical cloud-topped boundary layers: 1. A forcing framework with closed surface energy balance",2016,"10.1002/2016MS000655","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991082222&doi=10.1002%2f2016MS000655&partnerID=40&md5=f84191332f35d60ba6b0ade6b0fa2753","Large-eddy simulation (LES) of clouds has the potential to resolve a central question in climate dynamics, namely, how subtropical marine boundary layer (MBL) clouds respond to global warming. However, large-scale processes need to be prescribed or represented parameterically in the limited-area LES domains. It is important that the representation of large-scale processes satisfies constraints such as a closed energy balance in a manner that is realizable under climate change. For example, LES with fixed sea surface temperatures usually do not close the surface energy balance, potentially leading to spurious surface fluxes and cloud responses to climate change. Here a framework of forcing LES of subtropical MBL clouds is presented that enforces a closed surface energy balance by coupling atmospheric LES to an ocean mixed layer with a sea surface temperature (SST) that depends on radiative fluxes and sensible and latent heat fluxes at the surface. A variety of subtropical MBL cloud regimes (stratocumulus, cumulus, and stratocumulus over cumulus) are simulated successfully within this framework. However, unlike in conventional frameworks with fixed SST, feedbacks between cloud cover and SST arise, which can lead to sudden transitions between cloud regimes (e.g., stratocumulus to cumulus) as forcing parameters are varied. The simulations validate this framework for studies of MBL clouds and establish its usefulness for studies of how the clouds respond to climate change. © 2016. The Authors."
"6602600408;22958134600;57203200427;35362671700;","Regional climate engineering by radiation management: Prerequisites and prospects",2016,"10.1002/2016EF000440","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007324926&doi=10.1002%2f2016EF000440&partnerID=40&md5=b18a868db8ea3b5358a6102a77b9fe3e","Radiation management (RM), as an option to engineer the climate, is highly controversial and suffers from a number of ethical and regulatory concerns, usually studied in the context of the objective to mitigate the global mean temperature. In this article, we discuss the idea that RM can be differentiated and scaled in several dimensions with potential objectives being to influence a certain climate parameter in a specific region. Some short-lived climate forcers (e.g., tropospheric aerosols) exhibit strong geographical and temporal variability, potentially leading to limited-area climate responses. Marine cloud brightening and thinning or dissolution of cirrus clouds could be operated at a rather local scale. It is therefore conceivable that such schemes could be applied with the objective to influence the climate at a regional scale. From a governance perspective, it is desirable to avoid any substantial climate effects of regional RM outside the target region. This, however, could prove impossible for a sustained, long-term RM. In turn, regional RM during limited time periods could prove more feasible without effects beyond the target area. It may be attractive as it potentially provides the opportunity to target the suppression of some extreme events such as heat waves. Research is needed on the traceability of regional RM, for example, using detection and attribution methods. Incentives and implications of regional RM need to be examined, and new governance options have to be conceived. © 2016 The Authors."
"15047538100;6602135370;57207434250;15050523700;36242447900;","Clouds–SST relationship and interannual variability modes of Indian summer monsoon in the context of clouds and SSTs: observational and modelling aspects",2016,"10.1002/joc.4664","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84999748190&doi=10.1002%2fjoc.4664&partnerID=40&md5=054439371e7c81fce2adadd0e9c09c1d","This study examines the relationship between clouds and sea surface temperatures (SSTs) during Indian Summer Monsoon (ISM). Observation reveals dominance of high-level clouds in the monsoon region. NCEP Climate Forecast System version 2 (CFSv2) is able to replicate the observed high-level cloud fractions although it underestimates the magnitude. Cloud–SST relationship for observation depicts dominance of positive correlation over equatorial Indian Ocean region which is well recapitulated in CFSv2 simulations. To investigate the most dominating patterns of interannual variability of rainfall, SST and clouds, empirical orthogonal function (EOF) analysis is performed on seasonal JJAS (June–September) dataset. EOF analysis signifies that high-level clouds are highly correlated with rainfall for observations during ISM season. This study has also investigated relationship of clouds and El Niño Southern Oscillations (ENSO) and Indian Ocean Dipole (IOD) during ISM period. Interannual variations of clouds connote significant correlation with ENSO index (Nino 3/Nino 3.4). First principal component (PC1) of high-level clouds and ENSO index indicate significant negative correlation. EOF analysis based on observation also connotes that first mode (second) of EOF analysis is associated with ENSO (IOD). It is also confirmed by maximum covariance analysis (MCA). CFSv2 is also able to depict the significant negative correlation between PC1 of high-level clouds and ENSO index. Observation based second principal component (PC2) of high-level clouds and IOD index exhibits significant positive correlation. It gives indication that PC2 of observed high-level clouds can be associated with IOD. In contrast, PC2 of CFSv2 simulated high-level cloud and IOD index are not correlated. EOF analysis based on CFSv2 shows that the first mode of EOF analysis is associated with ENSO; however, second mode of EOF is not related with IOD. MCA analysis also supports these findings. It means that CFSv2 has good ability to represent ENSO as compared with IOD. © 2016 Royal Meteorological Society"
"7005642066;55672679900;57201278601;57197745085;36722732500;","Retrieval of radiative and microphysical properties of clouds from multispectral infrared measurements",2016,"10.1186/s40645-016-0108-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034097436&doi=10.1186%2fs40645-016-0108-3&partnerID=40&md5=e801712e7528d0a6631af741669ad84b","Satellite remote sensing of the macroscopic, microphysical, and optical properties of clouds are useful for studying spatial and temporal variations of clouds at various scales and constraining cloud physical processes in climate and weather prediction models. Instead of using separate independent algorithms for different cloud properties, a unified, optimal estimation-based cloud retrieval algorithm is developed and applied to moderate resolution imaging spectroradiometer (MODIS) observations using ten thermal infrared bands. The model considers sensor configurations, background surface and atmospheric profile, and microphysical and optical models of ice and liquid cloud particles and radiative transfer in a plane-parallel, multilayered atmosphere. Measurement and model errors are thoroughly quantified from direct comparisons of clear-sky observations over the ocean with model calculations. Performance tests by retrieval simulations show that ice cloud properties are retrieved with high accuracy when cloud optical thickness (COT) is between 0.1 and 10. Cloud-top pressure is inferred with uncertainty lower than 10 % when COT is larger than 0.3. Applying the method to a tropical cloud system and comparing the results with the MODIS Collection 6 cloud product shows good agreement for ice cloud optical thickness when COT is less than about 5. Cloud-top height agrees well with estimates obtained by the CO2 slicing method used in the MODIS product. The present algorithm can detect optically thin parts at the edges of high clouds well in comparison with the MODIS product, in which these parts are recognized as low clouds by the infrared window method. The cloud thermodynamic phase in the present algorithm is constrained by cloud-top temperature, which tends not to produce results with an ice cloud that is too warm and liquid cloud that is too cold. © 2016, The Author(s)."
"57205984068;57204043719;56022498200;7004289682;","Cloud fraction of liquid water clouds above Switzerland over the last 12 years",2016,"10.3390/cli4040048","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029378784&doi=10.3390%2fcli4040048&partnerID=40&md5=67025ab023bba3e02a25d33361b3e2e2","Cloud fraction (CF) plays a crucial role in the Earth's radiative energy budget and thus in the climate. Reliable long-term measurements of CF are rare. The ground-based TROpospheric WAter RAdiometer (TROWARA) at Bern, Switzerland continuously measures integrated liquid water and infrared brightness temperature with a time resolution of 6-11 s since 2004. The view direction of TROWARA is constant (zenith angle 50°), and all radiometer channels see the same volume of the atmosphere. TROWARA is sensitive to liquid water clouds while the microwave signal of ice clouds is negligible. By means of the measurement data we derived CF of thin liquid water clouds (1); thick supercooled liquid water clouds (2); thick warm liquid water clouds (3) and all liquid water clouds (4). The article presents the time series and seasonal climatologies of these four classes of CF. CF of thick supercooled liquid water clouds is larger than 15% from November to March. A significant negative trend of -0.29% ± 0.10%/yr is found for CF of thin liquid water clouds. No trends are found for the other classes (2, 3, 4) since their strong natural variability impedes a significant trend. However, CF of warm liquid water clouds increased by about +0.51% ± 0.27%/yr from 2004 to 2015. Finally, we performed a Mann-Kendall analysis of seasonal trends which gave several significant trends in the classes 1, 2 and 3. © 2016 by the authors."
"6602845217;35423159000;","The seasonally changing cloud feedbacks contribution to the ENSO seasonal phase-locking",2016,"10.1007/s00382-016-3034-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958817486&doi=10.1007%2fs00382-016-3034-6&partnerID=40&md5=d2a36ee131ebe9009a7314797d68fc1b","ENSO variability has a seasonal phase-locking, with SST anomalies on average decreasing during the beginning of the year and SST anomalies increasing during the second half of the year. As a result of this, the ENSO SST variability is smallest in April and the so call ‘spring barrier’ exists in the predictability of ENSO. In this study we analysis how the seasonal phase-locking of surface short wave radiation associated with cloud cover feedbacks contribute to this phenomenon. We base our analysis on observations and simplified climate model simulations. At the beginning of the year, the warmer mean SST in the eastern equatorial Pacific leads to deeper clouds whose anomalous variability are positively correlated with the underlying SST anomalies. These observations highlight a strong negative surface short wave radiation feedback at the beginning of the year in the eastern Pacific (NINO3 region). This supports the observed seasonal phase-locking of ENSO SST variability. This relation also exists in model simulations of the linear recharge oscillator and in the slab ocean model coupled to a fully complex atmospheric GCM. The Slab ocean simulation has seasonal phase-locking similar to observed mostly caused by similar seasonal changing cloud feedbacks as observed. In the linear recharge oscillator simulations seasonal phase-locking is also similar to observed, but is not just related to seasonal changing cloud feedbacks, but is also related to changes in the sensitivity of the zonal wind stress and to a lesser extent to seasonally change sensitivities to the thermocline depth. In summary this study has shown that the seasonal phase-locking, as observed and simulated, is linked to seasonally changing cloud feedbacks. © 2016, Springer-Verlag Berlin Heidelberg."
"6601954497;","Celestial mechanical causes of weather and climate change",2016,"10.1134/S0001433816070094","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009959534&doi=10.1134%2fS0001433816070094&partnerID=40&md5=939db37749b67cacac156f845eb7af53","This paper is devoted to the synchronization of synoptic processes in the atmosphere with tidal oscillations in the Earth’s rotational speed discovered by the author. The causes and effects of the synchronization are explained. Data are given on the monthly revolution of the Earth, tidal oscillations in the Earth’s rotational speed, and the main lunisolar cycles. An explanation is proposed for the causes of the Mul’tanovskii elementary synoptic periods and the manifestations of 4- and 8-year cycles in the climate system. It is shown that the 35-year Brückner cycle is attributed to the beat of the annual solar (365 days) and annual lunar (355 days) oscillations in meteorological characteristics. An explanation is proposed for how the lunisolar tides may affect the air temperature, which is based on the interaction of the gravitational lunisolar tides with the radiation conditions in the atmosphere (due to changes in the cloud cover). A discussion is given of the relationship between the fluctuations in the climatic characteristics and the change in the Earth’s rotational speed on decadal time scales. © 2016, Pleiades Publishing, Ltd."
"26643346600;36126495800;57190969147;","Impacts, Perceptions and Management of Climate-Related Risks to Cage Aquaculture in the Reservoirs of Northern Thailand",2016,"10.1007/s00267-016-0764-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984845711&doi=10.1007%2fs00267-016-0764-5&partnerID=40&md5=8a5732b6b71d9ef8777a0949628cf41e","Weather is suspected to influence fish growth and survival, and be a factor in mass mortality events in cage aquaculture in reservoirs. The purpose of this study was to identify the important climate-related risks faced by cage aquaculture farms; evaluate how these risks were currently being managed; and explore how farmers might adapt to the effects of climate change. Fish farmers were interviewed across the northern region of Thailand to get information on impacts, perceptions and practices. Drought or low water levels, heat waves, cold spells and periods with dense cloud cover, each caused significant financial losses. Perceptions of climate-related risks were consistent with experienced impacts. Risks are primarily managed in the short-term with techniques like aeration and reducing feed. In the mid-term farmers adjust stocking calendars, take financial measures and seek new information. Farmers also emphasize the importance of maintaining good relations with other stakeholders and reservoir management. Larger farms placed greater importance on risk management than small farms, even though types and levels of risk perceived were very similar. Most fish farms were managed by men alone, or men and women working together. Gender differences in risk perception were not detected, but women judged a few risk management practices as more important than men. Fish farmers perceived that climate is changing, but their perceptions were not strongly associated with recently having suffered impacts from extreme weather. The findings of this study provide important inputs to improving risk management under current and future climate. © 2016, Springer Science+Business Media New York."
"56119479900;55738957800;","Global climate impacts of stochastic deep convection parameterization in the NCAR CAM5",2016,"10.1002/2016MS000756","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991727679&doi=10.1002%2f2016MS000756&partnerID=40&md5=0b1711ad79f75f75a452d59d598c0916","In this study, the stochastic deep convection parameterization of Plant and Craig (PC) is implemented in the Community Atmospheric Model version 5 (CAM5) to incorporate the stochastic processes of convection into the Zhang-McFarlane (ZM) deterministic deep convective scheme. Its impacts on deep convection, shallow convection, large-scale precipitation and associated dynamic and thermodynamic fields are investigated. Results show that with the introduction of the PC stochastic parameterization, deep convection is decreased while shallow convection is enhanced. The decrease in deep convection is mainly caused by the stochastic process and the spatial averaging of input quantities for the PC scheme. More detrained liquid water associated with more shallow convection leads to significant increase in liquid water and ice water paths, which increases large-scale precipitation in tropical regions. Specific humidity, relative humidity, zonal wind in the tropics, and precipitable water are all improved. The simulation of shortwave cloud forcing (SWCF) is also improved. The PC stochastic parameterization decreases the global mean SWCF from −52.25 W/m2 in the standard CAM5 to −48.86 W/m2, close to −47.16 W/m2 in observations. The improvement in SWCF over the tropics is due to decreased low cloud fraction simulated by the stochastic scheme. Sensitivity tests of tuning parameters are also performed to investigate the sensitivity of simulated climatology to uncertain parameters in the stochastic deep convection scheme. © 2016. The Authors."
"23995988300;16642923700;57203073322;","Leaf/shoot level ecophysiology in two broadleaf and two needle-leaf species under representative cloud regimes at alpine treeline",2016,"10.1093/jpe/rtw019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85014741877&doi=10.1093%2fjpe%2frtw019&partnerID=40&md5=808d0877f1e55aa6239b213e3ba45319","Aims The effects of clouds are now recognized as critically important to the understanding of climate change impacts on ecosystems. Regardless, few studies have focused specifically on the ecophysiological responses of plants to clouds. Most continental mountain ranges are characterized by common convective cloud formation in the afternoons, yet little is known regarding this influence on plant water and carbon relations. Here we compare the ecophysiology of two contrasting, yet ubiquitous growth forms, needle-leaf and broadleaf, under representative cloud regimes of the Snowy Range, Medicine Bow Mountains, southeastern Wyoming, USA. Methods Photosynthetic gas exchange, water use efficiency, xylem water potentials and micrometeorological data were measured on representative clear, overcast and partly cloudy days during the summers of 2012 and 2013 for two indigenous broadleaf (Caltha leptosepala and Arnica parryi) and two needle-leaf species (Picea engelmannii and Abies lasiocarpa) that co-occur contiguously. Important Findings Reductions in sunlight with cloud cover resulted in more dramatic declines in photosynthesis for the two broadleaf species (ca. 50-70% reduction) versus the two conifers (no significant difference). In addition, the presence of clouds corresponded with lower leaf conductance, transpiration and plant water status in all species. However, the more constant photosynthesis in conifers under all cloud conditions, coupled with reduced transpiration, resulted in greater water use efficiency (ca. 25% higher) than the broadleaf species. These differences appear to implicate the potential importance of natural cloud patterns in the adaptive ecophysiology of these two contrasting, but common, plant growth forms."
"56402758400;7102322882;","Exploring the Venus global super-rotation using a comprehensive general circulation model",2016,"10.1016/j.pss.2016.09.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84993977990&doi=10.1016%2fj.pss.2016.09.001&partnerID=40&md5=0af34b866fc55dcac6fb7af056f55ee5","The atmospheric circulation in Venus is well known to exhibit strong super-rotation. However, the atmospheric mechanisms responsible for the formation of this super-rotation are still not fully understood. In this work, we developed a new Venus general circulation model to study the most likely mechanisms driving the atmosphere to the current observed circulation. Our model includes a new radiative transfer, convection and suitably adapted boundary layer schemes and a dynamical core that takes into account the dependence of the heat capacity at constant pressure with temperature. The new Venus model is able to simulate a super-rotation phenomenon in the cloud region quantitatively similar to the one observed. The mechanisms maintaining the strong winds in the cloud region were found in the model results to be a combination of zonal mean circulation, thermal tides and transient waves. In this process, the semi-diurnal tide excited in the upper clouds has a key contribution in transporting axial angular momentum mainly from the upper atmosphere towards the cloud region. The magnitude of the super-rotation in the cloud region is sensitive to various radiative parameters such as the amount of solar radiative energy absorbed by the surface, which controls the static stability near the surface. In this work, we also discuss the main difficulties in representing the flow below the cloud base in Venus atmospheric models. Our new radiative scheme is more suitable for 3D Venus climate models than those used in previous work due to its easy adaptability to different atmospheric conditions. This flexibility of the model was crucial to explore the uncertainties in the lower atmospheric conditions and may also be used in the future to explore, for example, dynamical-radiative-microphysical feedbacks. © 2016 Elsevier Ltd"
"55519994900;23991212200;56297863500;6701835010;7202208382;","Impacts of cloud superparameterization on projected daily rainfall intensity climate changes in multiple versions of the Community Earth System Model",2016,"10.1002/2016MS000715","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995687626&doi=10.1002%2f2016MS000715&partnerID=40&md5=a98ac573b26cb3dade27b11fd749e462","Changes in the character of rainfall are assessed using a holistic set of statistics based on rainfall frequency and amount distributions in climate change experiments with three conventional and superparameterized versions of the Community Atmosphere Model (CAM and SPCAM). Previous work has shown that high-order statistics of present-day rainfall intensity are significantly improved with superparameterization, especially in regions of tropical convection. Globally, the two modeling approaches project a similar future increase in mean rainfall, especially across the Inter-Tropical Convergence Zone (ITCZ) and at high latitudes, but over land, SPCAM predicts a smaller mean change than CAM. Changes in high-order statistics are similar at high latitudes in the two models but diverge at lower latitudes. In the tropics, SPCAM projects a large intensification of moderate and extreme rain rates in regions of organized convection associated with the Madden Julian Oscillation, ITCZ, monsoons, and tropical waves. In contrast, this signal is missing in all versions of CAM, which are found to be prone to predicting increases in the amount but not intensity of moderate rates. Predictions from SPCAM exhibit a scale-insensitive behavior with little dependence on horizontal resolution for extreme rates, while lower resolution (∼2°) versions of CAM are not able to capture the response simulated with higher resolution (∼1°). Moderate rain rates analyzed by the “amount mode” and “amount median” are found to be especially telling as a diagnostic for evaluating climate model performance and tracing future changes in rainfall statistics to tropical wave modes in SPCAM. © 2016. The Authors."
"28367935500;6603982006;56033405100;7201627869;6602761005;6507671561;57192410585;16304488000;55544443300;22134875500;7202048112;57111001300;6701670597;55803016100;35079444600;36677956900;36187387300;7102875574;7401548835;56109268200;6507501796;57190684584;55537426400;57192410641;","The tropical rain belts with an annual cycle and a continent model intercomparison project: TRACMIP",2016,"10.1002/2016MS000748","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006306758&doi=10.1002%2f2016MS000748&partnerID=40&md5=15162ef5fba0e50329d7a9f9ac87fa30","This paper introduces the Tropical Rain belts with an Annual cycle and a Continent Model Intercomparison Project (TRACMIP). TRACMIP studies the dynamics of tropical rain belts and their response to past and future radiative forcings through simulations with 13 comprehensive and one simplified atmosphere models coupled to a slab ocean and driven by seasonally varying insolation. Five idealized experiments, two with an aquaplanet setup and three with a setup with an idealized tropical continent, fill the space between prescribed-SST aquaplanet simulations and realistic simulations provided by CMIP5/6. The simulations reproduce key features of present-day climate and expected future climate change, including an annual-mean intertropical convergence zone (ITCZ) that is located north of the equator and Hadley cells and eddy-driven jets that are similar to present-day climate. Quadrupling CO2 leads to a northward ITCZ shift and preferential warming in Northern high latitudes. The simulations show interesting CO2-induced changes in the seasonal excursion of the ITCZ and indicate a possible state dependence of climate sensitivity. The inclusion of an idealized continent modulates both the control climate and the response to increased CO2; for example, it reduces the northward ITCZ shift associated with warming and, in some models, climate sensitivity. In response to eccentricity-driven seasonal insolation changes, seasonal changes in oceanic rainfall are best characterized as a meridional dipole, while seasonal continental rainfall changes tend to be symmetric about the equator. This survey illustrates TRACMIP's potential to engender a deeper understanding of global and regional climate and to address questions on past and future climate change. © 2016. The Authors."
"56429516800;6603663168;56118948700;14322050300;","Comparing COSMO-CLM simulations and MODIS data of snow cover extent and distribution over Italian Alps",2016,"10.1007/s00382-016-3054-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960364803&doi=10.1007%2fs00382-016-3054-2&partnerID=40&md5=82da01e87a77da1d5f3fed4d62e42895","Snow cover maps from Earth Observation (EO) satellites are valuable datasets containing large-scale information on snow cover extent, snow cover distribution and snow cover duration. In evaluating the performances of Regional Climate Models, EO data can be a valid piece of information alternative to in-situ measurements, which require a dense network of stations covering the entire altitudinal range and techniques for interpolating the values. In this context, MODIS snow products play a leading role providing several types of snow cover maps with high spatial and temporal resolutions. Here, we assess snow cover outputs of a high resolution Regional Climate Model (RCM) using MODIS maps of snow covered area over the Po river basin, northern Italy. The dataset consists of 9 years of MODIS data (2003–2011) cleaned from cloud cover by means of a cloud removal procedure. The maps have 500 m spatial resolution and daily temporal resolution. The RCM considered is COSMO-CLM, run at 0.0715° resolution (about 8 km) and coupled with the soil module TERRA_ML. The ERA-Interim reanalyses are used as initial and boundary conditions. The results show a good agreement between observed and simulated snow cover duration and extension. COSMO-CLM is able to reproduce the inter-annual variabilities of snow cover features as well as the seasonal trend of snow cover duration and extension. Limitations emerge when the RCM simulates the progressive depletion of the snow cover in spring. Simulated snowmelt occurs faster than the observed one. Then, we investigate the influence of the spatial resolution of the climate model. The simulation at 0.0715° (about 8 km) is compared to a simulation performed at 0.125° (about 14 km). The comparison highlights the benefits provided by the higher spatial resolution in the accumulation season, reflecting the improvements obtained in temperature and precipitation fields. © 2016, Springer-Verlag Berlin Heidelberg."
"7005035762;36058918500;6701592014;7404521962;16480992300;6507296473;7005746204;7410041005;","Recommendations for improving U.S. NSF-supported airborne microwave radiometry",2016,"10.1175/BAMS-D-15-00081.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011715929&doi=10.1175%2fBAMS-D-15-00081.1&partnerID=40&md5=b25a934662a845f4ea13e596d0b98370","The cloudy, humid atmosphere remains the most important weather and climate forecasting chal-lenge. Airborne remote sensors such as radars and lidars have revolutionized information on aero�sol, moisture, cloud, and precipitation vertical structure, increasing the information gathered from in situ measurements alone. In recog�nition, the National Science Foundation (NSF) has expanded its aircraft deployment resources to the remote sensors. The integrated water-phase measurements provide important geophysical constraints on hydrome�teor and vapor profiles derived from active sensors, and the profiling and mapping of the atmosphere is more comprehensive than that available from in situ observations."
"8770227900;8598730000;7202669639;","Cold air drainage flows subsidize montane valley ecosystem productivity",2016,"10.1111/gcb.13320","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971617672&doi=10.1111%2fgcb.13320&partnerID=40&md5=1816213687bde043aa3792ea236373b3","In mountainous areas, cold air drainage from high to low elevations has pronounced effects on local temperature, which is a critical driver of many ecosystem processes, including carbon uptake and storage. Here, we leverage new approaches for interpreting ecosystem carbon flux observations in complex terrain to quantify the links between macro-climate condition, drainage flows, local microclimate, and ecosystem carbon cycling in a southern Appalachian valley. Data from multiple long-running climate stations and multiple eddy covariance flux towers are combined with simple models for ecosystem carbon fluxes. We show that cold air drainage into the valley suppresses local temperature by several degrees at night and for several hours before and after sunset, leading to reductions in growing season respiration on the order of ~8%. As a result, we estimate that drainage flows increase growing season and annual net carbon uptake in the valley by >10% and >15%, respectively, via effects on microclimate that are not be adequately represented in regional- and global-scale terrestrial ecosystem models. Analyses driven by chamber-based estimates of soil and plant respiration reveal cold air drainage effects on ecosystem respiration are dominated by reductions to the respiration of aboveground biomass. We further show that cold air drainage proceeds more readily when cloud cover and humidity are low, resulting in the greatest enhancements to net carbon uptake in the valley under clear, cloud-free (i.e., drought-like) conditions. This is a counterintuitive result that is neither observed nor predicted outside of the valley, where nocturnal temperature and respiration increase during dry periods. This result should motivate efforts to explore how topographic flows may buffer eco-physiological processes from macroscale climate change. © 2016 John Wiley & Sons Ltd"
"57203740702;55796506900;57189237711;42263280300;","A modeling study of effective radiative forcing and climate response due to increased methane concentration",2016,"10.1016/j.accre.2016.12.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008500266&doi=10.1016%2fj.accre.2016.12.001&partnerID=40&md5=2300b7e4dc7ffcc9d11f5f3370c0ec0a","An atmospheric general circulation model BCC_AGCM2.0 and observation data from ARIS were used to calculate the effective radiative forcing (ERF) due to increased methane concentration since pre-industrial times and its impacts on climate. The ERF of methane from 1750 to 2011 was 0.46 W m−2 by taking it as a well-mixed greenhouse gas, and the inhomogeneity of methane increased its ERF by about 0.02 W m−2. The change of methane concentration since pre-industrial led to an increase of 0.31 °C in global mean surface air temperature and 0.02 mm d−1 in global mean precipitation. The warming was prominent over the middle and high latitudes of the Northern Hemisphere (with a maximum increase exceeding 1.4 °C). The precipitation notably increased (maximum increase of 1.8 mm d−1) over the ocean between 10°N and 20°N and significantly decreased (maximum decrease &gt;–0.6 mm d−1) between 10°S and 10°N. These changes caused a northward movement of precipitation cell in the Intertropical Convergence Zone (ITCZ). Cloud cover significantly increased (by approximately 4%) in the high latitudes in both hemispheres, and sharply decreased (by approximately 3%) in tropical areas. © 2017 National Climate Center (China Meteorological Administration)"
"57188866963;57210687618;","Moisture-radiative cooling instability",2016,"10.1002/2016MS000763","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995655013&doi=10.1002%2f2016MS000763&partnerID=40&md5=ce8e3bc769d3fe24fe9d633ad2154cdd","Radiative-convective equilibrium (RCE)—the statistical equilibrium state of the atmosphere where convection and radiation interact in the absence of lateral transport—is widely used as a basic-state model of the tropical atmosphere. The possibility that RCE may be unstable to development of large-scale circulation has been raised by recent modeling, theoretical, and observational studies, and could have profound consequences for our understanding of tropical meteorology and climate. Here, we study the interaction between moisture and radiative cooling as a contributor to instability of RCE. We focus on whether the total atmospheric radiative cooling decreases with column water vapor; this condition, which we call moisture-radiative cooling instability (MRCI), provides the potential for unstable growth of moist or dry perturbations. Analytic solutions to the gray-gas radiative transfer equations show that MRCI is satisfied when the total column optical depth—linked to column water vapor—exceeds a critical threshold. Both the threshold and the growth rate of the instability depend strongly on the shape of the water vapor perturbation. Calculations with a realistic radiative transfer model confirm the existence of MRCI for typical tropical values of column water vapor, but show even stronger dependence on the vertical structure of water vapor perturbation. Finally, we analyze the sensitivity of atmospheric radiative cooling to variability in column water vapor in observed tropical soundings. We find that clear-sky MRCI is satisfied across a range of locations and seasons in the real tropical atmosphere, with a partial growth rate of ∼1 month. © 2016. The Authors."
"36456423100;7203047936;","Uncertainty in Fengyun-3C Microwave Humidity Sounder Measurements at 118 GHz With Respect to Simulations From GPS RO Data",2016,"10.1109/TGRS.2016.2587878","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983611770&doi=10.1109%2fTGRS.2016.2587878&partnerID=40&md5=e958e0036bc63c2dd5abfb549fd4d608","Microwave Humidity Sounder (MWHS) onboard the Chinese FengYun-3C satellite has a total of 12 channels. Eight of these channels are located near the 118-GHz oxygen absorption band for probing atmospheric temperature and humidity fields from space. While the water vapor sounding channels near 183 GHz have been extensively studied in the past, we report the first satellite observations at 118 GHz. In this paper, the MWHS calibration accuracy is assessed by comparing the satellite observations with simulations. Using the collocated Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) radio occultation (RO) data in clear-sky conditions as inputs to Community Radiative Transfer Model, MWHS brightness temperatures are simulated for the five upper level sounding channels 2-9 located near the 118-GHz oxygen absorption band. For quality control of clear-sky radiance, a new cloud index is first developed based on the two MWHS window channels 1 and 10. Monthly mean biases of the antenna brightness temperature observations for the 118-GHz sounding channels are quantified by using more than 2000-5000 collocated COSMIC and MWHS data from August 2014 to February 2015. It is found that the bias of MWHS data relative to COSMIC RO simulation is dependent on channel and ranges within ±1.5 K. The standard deviation from the bias is the largest at MWHS channel 2, indicating a larger variability of the measurements of channel 2 than the other channels. © 2016 IEEE."
"55873010300;13611521400;","Improving ENSO periodicity simulation by adjusting cumulus entrainment in BCC_CSMs",2016,"10.1016/j.dynatmoce.2016.10.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84993984016&doi=10.1016%2fj.dynatmoce.2016.10.005&partnerID=40&md5=2f11c40914ac461eba9a91ec9c85dd56","The simulation of El Niño-Southern Oscillation (ENSO) phenomenon is a challenging issue for coupled climate models. This study focuses on the ENSO periodicity simulated by Beijing Climate Center Climate System Models (BCC_CSM1.1 and BCC_CSM1.1m) which can reproduce reasonably well ENSO amplitude as observations. However, the major period of ENSO simulated by the BCC_CSMs is around 2.4 years, which is much shorter than that in observations. Compared with other 24 coupled models in Coupled Model Intercomparison Project Phase 5 (CMIP5), BCC_CSMs produce a very unrealistic ENSO peak period. Such a bias in simulating periodicity is suggested as a consequence of the severely underestimated air-sea coupling intensity in BCC_CSMs. To test this hypothesis, a quantitative method is developed to diagnose the linear ENSO frequency. As an effort to improve the ENSO simulation in BCC_CSMs, three experiments are performed with varying entrainment rates in the cumulus convection parameterization scheme of BCC_CSM1.1m. A more realistic ENSO period of about 3.3 years can be generated by the model with an inflated entrainment rate. When the cumulus entrainment is increased by 10%, the ENSO-related convective precipitation will enhance in the equatorial central to eastern Pacific. This anomalous convective heating induces an intensified surface westerly wind stress to the west of the anomalous convection center and as a result, the air-sea coupling intensity becomes larger, which contributes to a longer period of ENSO based on previous theories. In addition, the pronounced eastward extension of ENSO-related surface wind stress could also be the secondary factor to generate a lower frequency of ENSO in BCC_CSMs. Our study proposes a method to reduce the biases in ENSO periodicity simulation and puts more insights into the importance of adjusting atmospheric convection to reproduce ENSO properties in coupled model. © 2016 Elsevier B.V."
"57203049177;24329376600;36010237000;8696069500;35547807400;","Small global-mean cooling due to volcanic radiative forcing",2016,"10.1007/s00382-016-3055-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960374743&doi=10.1007%2fs00382-016-3055-1&partnerID=40&md5=fac78643ea2c6aa3773f3c587d76618f","In both the observational record and atmosphere-ocean general circulation model (AOGCM) simulations of the last ∼ 150 years, short-lived negative radiative forcing due to volcanic aerosol, following explosive eruptions, causes sudden global-mean cooling of up to ∼ 0.3 K. This is about five times smaller than expected from the transient climate response parameter (TCRP, K of global-mean surface air temperature change per W m−2 of radiative forcing increase) evaluated under atmospheric CO2 concentration increasing at 1 % yr−1. Using the step model (Good et al. in Geophys Res Lett 38:L01703, 2011. doi:10.1029/2010GL045208), we confirm the previous finding (Held et al. in J Clim 23:2418–2427, 2010. doi:10.1175/2009JCLI3466.1) that the main reason for the discrepancy is the damping of the response to short-lived forcing by the thermal inertia of the upper ocean. Although the step model includes this effect, it still overestimates the volcanic cooling simulated by AOGCMs by about 60 %. We show that this remaining discrepancy can be explained by the magnitude of the volcanic forcing, which may be smaller in AOGCMs (by 30 % for the HadCM3 AOGCM) than in off-line calculations that do not account for rapid cloud adjustment, and the climate sensitivity parameter, which may be smaller than for increasing CO2 (40 % smaller than for 4 × CO2 in HadCM3). © 2016, The Author(s)."
"55433794500;7004479395;6507774221;56060845000;","A sub km resolution global database of surface reflectance and emissivity based on 10-years of MODIS data",2016,"10.1016/j.isprsjprs.2016.10.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996614803&doi=10.1016%2fj.isprsjprs.2016.10.004&partnerID=40&md5=edb252374a9b5898070da47b924036f1","The MODIS instruments have been flying onboard the Terra and Aqua platforms and have acquired Earth observation data since early 2000 and mid 2002, respectively. After atmospheric correction, the collected data allows the monitoring of the land cover dynamics. Here, we describe a data processing scheme to generate Earth reflectance and emissivity time series at a sub-kilometer spatial resolution and with a period of 8 days. The data processing scheme removes residual cloud and aerosol contamination in the MODIS products, applies directional correction, and fills the gaps resulting from persistent cloud cover. The resulting database, referred to FondsDeSol, offers a significant improvement with respect to the first version proposed in (Gonzalez et al., 2010), and covers a period of ten years against only one year for the first version. The first motivation of the database is to improve the estimation of at sensor radiances for the design of future sensor in the optical domain. Nevertheless, such database opens the way to new research topics like land surface dynamics, land cover changes, and inter-annual variations due to climate perturbations. © 2016 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS)"
"55589605400;35091692800;54909969100;35579822900;56059347500;7402534046;7007018426;","Multisite analysis of land surface phenology in North American temperate and boreal deciduous forests from Landsat",2016,"10.1016/j.rse.2016.09.014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988040365&doi=10.1016%2fj.rse.2016.09.014&partnerID=40&md5=2dfb3d810450c5de366181d4f7ed1d7d","Forests play important roles in the Earth's climate system and global carbon cycle. Therefore, a critical need exists to improve our understanding of how the growing seasons of forests are changing, and by extension, how the composition and function of forests will respond to future climate change. Coarse spatial resolution satellite remote sensing has been widely used to monitor and map the phenology of terrestrial ecosystems at regional to global scales, and despite widespread agreement that the growing season of Northern Hemisphere forests is changing, the spatial resolution of these data sources imposes significant limitations on the character and quality of inferences that can be drawn from them. In particular, the spatial resolution afforded by instruments such as MODIS does not resolve ecologically important landscape-scale patterns in phenology. With this issue in mind, here we evaluate the ability of a newly developed Landsat phenology algorithm (LPA) to reconstruct a 32-year time series for the start and end of the growing season in North American temperate and boreal forests. We focus on 13 “sidelap” regions located between overlapping Landsat scenes that span a large geographic range of temperate and boreal forests, and evaluate the quality and character of LPA-derived start and end of growing season (SOS and EOS) dates using several independent data sources. On average, SOS and EOS dates were detected for about two-thirds of the 32 years included in our analysis, with the remaining one-third missing due to cloud cover. Moreover, there was generally better agreement between ground observations and LPA-derived estimates of SOS dates than for EOS across the 13 sites included in our study. Our results demonstrate that, despite the presence of time series gaps, LPA provides a robust basis for retrospective analysis of long-term changes in spring and autumn deciduous forest phenology over the last three decades. Finally, our results support the potential for monitoring land surface phenology at 30 m spatial resolution in near real-time by combining time series from multiple sensors such as the Landsat Operational Land Imager and the Sentinel 2 MultiSpectral Instrument. © 2016 Elsevier Inc."
"36862230600;57203482247;6701711144;6506697172;23009303500;6602427667;","Buried iceberg-keel scouring on the southern Spitsbergenbanken, NW Barents Sea",2016,"10.1016/j.margeo.2016.10.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992520929&doi=10.1016%2fj.margeo.2016.10.005&partnerID=40&md5=ac70fb367397dcbb42f0f86cc4ed4b34","PARASOUND (3.5 kHz) subbottom echosounder profiles acquired on the southern Spitsbergenbanken, NW Barents Sea, show iceberg-keel scouring features which are buried by sediment that accumulated during the post Last Glacial Maximum (LGM) sea-level rise. Four acoustic units (Units 1 to 4 in stratigraphic order) were differentiated, based on the characterization of their acoustic facies and reflection surfaces. Unit 1 shows a chaotic internal structure and is interpreted as a glacial till, whereas the laminated Units 2 to 4 accumulated by sediment settling from suspension clouds and bottom currents during the last deglaciation phase. The top of Unit 2 was frequently incised by iceberg keels, resulting in up to 12 m deep ploughmarks which were later filled and buried by Unit 3 and 4 sediments. Three main paleo-evironmental changes controlled the evolution of the facies succession: (1) The major shift from till formation (Unit 1) below grounded ice to the accumulation of laminated sediments (Unit 2) which are inferred to reflect ice lifting and meltwater release; (2) Iceberg-keel scouring after sedimentation of Unit 2; (3) the probable abrupt termination of iceberg-keel scouring related to the glacio-eustatic sea-level rise. A linkage between these episodes of changes and short-lasting phases of rapid post LGM sea-level rise, such as meltwater pulses, is inferred, although further studies are needed to better understand the temporal and genetic relationships between the sedimentary events recognized in the Barents Sea and climate changes. © 2016 Elsevier B.V."
"36908840200;57111001300;7202048112;55476830600;55656929800;6506328135;","Sources and pathways of the upscale effects on the Southern Hemisphere jet in MPAS-CAM4 variable-resolution simulations",2016,"10.1002/2016MS000743","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85000983826&doi=10.1002%2f2016MS000743&partnerID=40&md5=9025e1dd7fe7c153efcc444a3492668e","Impacts of regional grid refinement on large-scale circulations (“upscale effects”) were detected in a previous study that used the Model for Prediction Across Scales-Atmosphere coupled to the physics parameterizations of the Community Atmosphere Model version 4. The strongest upscale effect was identified in the Southern Hemisphere jet during austral winter. This study examines the detailed underlying processes by comparing two simulations at quasi-uniform resolutions of 30 and 120 km to three variable-resolution simulations in which the horizontal grids are regionally refined to 30 km in North America, South America, or Asia from 120 km elsewhere. In all the variable-resolution simulations, precipitation increases in convective areas inside the high-resolution domains, as in the reference quasi-uniform high-resolution simulation. With grid refinement encompassing the tropical Americas, the increased condensational heating expands the local divergent circulations (Hadley cell) meridionally such that their descending branch is shifted poleward, which also pushes the baroclinically unstable regions, momentum flux convergence, and the eddy-driven jet poleward. This teleconnection pathway is not found in the reference high-resolution simulation due to a strong resolution sensitivity of cloud radiative forcing that dominates the aforementioned teleconnection signals. The regional refinement over Asia enhances Rossby wave sources and strengthens the upper level southerly flow, both facilitating the cross-equatorial propagation of stationary waves. Evidence indicates that this teleconnection pathway is also found in the reference high-resolution simulation. The result underlines the intricate diagnoses needed to understand the upscale effects in global variable-resolution simulations, with implications for science investigations using the computationally efficient modeling framework. © 2016. The Authors."
"57202379700;36712256000;7006338905;16637291100;","Development of a Mid-Infrared Sea and Lake Ice Index (MISI) using the GOES imager",2016,"10.3390/rs8121015","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019703477&doi=10.3390%2frs8121015&partnerID=40&md5=5c63e13b04cd38b1fc737488c5ae31a9","An automated ice-mapping algorithm has been developed and evaluated using data from the GOES-13 imager. The approach includes cloud-free image compositing as well as image classification using spectral criteria. The algorithm uses an alternative snow index to the Normalized Difference Snow Index (NDSI). The GOES-13 imager does not have a 1.6 μm band, a requirement for NDSI; however, the newly proposed Mid-Infrared Sea and Lake Ice Index (MISI) incorporates the reflective component of the 3.9 μm or mid-infrared (MIR) band, which the GOES-13 imager does operate. Incorporating MISI into a sea or lake ice mapping algorithm allows for mapping of thin or broken ice with no snow cover (nilas, frazil ice) and thicker ice with snow cover to a degree of confidence that is comparable to other ice mapping products. The proposed index has been applied over the Great Lakes region and qualitatively compared to the Interactive Multi-sensor Snow and Ice Mapping System (IMS), the National Ice Center ice concentration maps and MODIS snow cover products. The application of MISI may open additional possibilities in climate research using historical GOES imagery. Furthermore, MISI may be used in addition to the current NDSI in ice identification to build more robust ice-mapping algorithms for the next generation GOES satellites. © 2016 by the authors."
"7401829462;26435318900;15044351300;8579929300;7202747495;","Concentrations of mineral aerosol from desert to plains across the central Rocky Mountains, western United States",2016,"10.1016/j.aeolia.2016.09.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988951877&doi=10.1016%2fj.aeolia.2016.09.001&partnerID=40&md5=3dde545c024927720913788276ade632","Mineral dusts can have profound effects on climate, clouds, ecosystem processes, and human health. Because regional dust emission and deposition in western North America are not well understood, measurements of total suspended particulate (TSP) from 2011 to 2013 were made along a 500-km transect of five remote sites in Utah and Colorado, USA. The TSP concentrations in μg m−3 adjusted to a 24-h period were relatively high at the two westernmost, dryland sites at Canyonlands National Park (mean = 135) and at Mesa Verde National Park (mean = 99), as well as at the easternmost site on the Great Plains (mean = 143). The TSP concentrations at the two intervening montane sites were less, with more loading on the western slope of the Rocky Mountains (Telluride, mean = 68) closest to the desert sites compared with the site on the eastern slope (Niwot Ridge, mean = 58). Dust concentrations were commonly highest during late winter-late spring, when Pacific frontal storms are the dominant causes of regional wind. Low concentrations (&lt;7 wt%) of organic matter indicated that rock-derived mineral particles composed most TSP. Most TSP mass was carried by particle sizes larger than 10 μm (PM&gt;10), as revealed by relatively low average daily concentrations of fine (&lt;5 μg m−3; PM2.5) and coarse (&lt;10 μg m−3; PM2.5–10) fractions monitored at or near four sites. Standard air-quality measurements for PM2.5 and PM10 apparently do not capture the large majority of mineral-particulate pollution in the remote western interior U.S. © 2016"
"57104432400;57210337677;35620654900;","Evaluation of the representativeness of ground-based visibility for analysing the spatial and temporal variability of aerosol optical thickness in China",2016,"10.1016/j.atmosenv.2016.09.060","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989322080&doi=10.1016%2fj.atmosenv.2016.09.060&partnerID=40&md5=5928df391b302f10bab11b697f83d327","Although visibility is a widely-used indicator to quantify the aerosol loadings, only a few studies have been analyzed the representativeness of visibility in deriving Aerosol Optical Thickness (AOT). In this paper, ground-based visibility, MODerate-resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR) monthly AOT products between July 2002 and December 2014 were analyzed in order to extract the dominant modes of variability using the Singular Value Decomposition (SVD) method. The method has significant merit to reduce data dimension and examine both spatial and temporal variability simultaneously. Results indicated that the satellite retrieved AOTs agreed well with ground-based visibility in terms of inter-annual variability. The correlation coefficients in the first deseasonalized mode are greater than 0.65 between visibility and satellite AOT products. However, large differences were observed in the seasonal variability between ground-based visibility and AOT. In addition, Aerosol vertical distribution from LIdar climatology of Vertical Aerosol Structure for space-based lidar simulation studies (LIVAS) and cloud data from ground-based meteorological station were used to investigate the seasonal variability disagreement. The AOT values derived from LIVAS extinction coefficients between 0 and 500 m above surface have a stronger relationship with visibility, than total column AOT with visibility. It also indicates that seasonal variation of aerosol vertical distribution is the main cause of the disagreement between two parameters, and the uncertainties of satellite products also contribute to the disagreement. Results in this study highlighted that the visibility observation could only be used to depict the inter-annual AOT and more ancillary information could be used for studying seasonal AOT variation. © 2016 Elsevier Ltd"
"55980874700;7004977068;7006140875;7005801679;6603834154;","Snow season variability in a boreal-Arctic transition area monitored by MODIS data",2016,"10.1088/1748-9326/11/12/125005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008193658&doi=10.1088%2f1748-9326%2f11%2f12%2f125005&partnerID=40&md5=b6b1fd9712b60fb67a91daeaca2eb7e9","The duration and extent of snow cover is expected to change rapidly with climate change. Therefore, there is a need for improved monitoring of snow for the benefit of forecasting, impact assessments and the population at large. Remotely sensed techniques prove useful for remote areas where there are few field-based monitoring stations. This paper reports on a study of snow season using snow cover area fraction data from the two northernmost counties in Norway, Troms and Finnmark. The data are derived from the daily 500 m standard snow product (MOD10A1) from the NASA Terra MODerate Resolution Imaging Spectroradiometer (MODIS) sensor for the 2000-2010 period. This dataset has been processed with multi-temporal interpolation to eliminate clouds. The resulting cloud-free daily time series of snow cover fraction maps, have subsequently been used to derive the first and last snow-free day for the entire study area. In spring, the correlation between the first snow-free day mapped by MODIS data and snow data from 40 meteorological stations was highly significant (p < 0.05) for 36 of the stations, and with a of bias of less than 10 days for 34 of the stations. In autumn, 31 of the stations show highly significant (p < 0.05) correlation with MODIS data, and the bias was less than 10 days for 27 of the stations. However, in some areas and some years, the start and end of the snow season could not be detected due to long overcast periods. In spring 2002 and 2004 the first snow-free day was early, but arrived late in 2000, 2005 and 2008. In autumn 2009 snowfall arrived more than 7 days earlier in 50% of the study area as compared to the 2000-2010 average. MODIS-based snow season products will be applicable for a wide range of sectors including hydrology, nature-based industries, climate change studies and ecology. Therefore refinement and further testing of this method should be encouraged. © 2016 IOP Publishing Ltd."
"55577875600;57192212652;55717074000;55802246600;56384704800;57200055610;7406500188;","Impacts of global open-fire aerosols on direct radiative, cloud and surface-albedo effects simulated with CAM5",2016,"10.5194/acp-16-14805-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85001000760&doi=10.5194%2facp-16-14805-2016&partnerID=40&md5=57c72589147298ee90b68f856cb98436","Aerosols from open-land fires could significantly perturb the global radiation balance and induce climate change. In this study, Community Atmosphere Model version 5 (CAM5) with prescribed daily fire aerosol emissions is used to investigate the spatial and seasonal characteristics of radiative effects (REs, relative to the case of no fires) of open-fire aerosols including black carbon (BC) and particulate organic matter (POM) from 2003 to 2011. The global annual mean RE from aerosol-radiation interactions (REari) of all fire aerosols is 0.16±0.01Wm-2 (1σ uncertainty), mainly due to the absorption of fire BC (0.25±0.01Wm-2), while fire POM induces a small effect (-0.05 and 0.04±0.01Wm-2 based on two different methods). Strong positive REari is found in the Arctic and in the oceanic regions west of southern Africa and South America as a result of amplified absorption of fire BC above low-level clouds, in general agreement with satellite observations. The global annual mean RE due to aerosol-cloud interactions (REaci) of all fire aerosols is -0.70±0.05Wm-2, resulting mainly from the fire POM effect (-0.59±0.03Wm-2). REari (0.43±0.03Wm-2) and REaci (-1.38±0.23Wm-2) in the Arctic are stronger than in the tropics (0.17±0.02 and -0.82±0.09Wm-2 for REari and REaci), although the fire aerosol burden is higher in the tropics. The large cloud liquid water path over land areas and low solar zenith angle of the Arctic favor the strong fire aerosol REaci (up to -15Wm-2) during the Arctic summer. Significant surface cooling, precipitation reduction and increasing amounts of low-level cloud are also found in the Arctic summer as a result of the fire aerosol REaci based on the atmosphere-only simulations. The global annual mean RE due to surface-albedo changes (REsac) over land areas (0.03±0.10Wm-2) is small and statistically insignificant and is mainly due to the fire BC-in-snow effect (0.02Wm-2) with the maximum albedo effect occurring in spring (0.12Wm-2) when snow starts to melt. © Author(s) 2016. CC Attribution 3.0 License."
"55803016100;15026371500;","The impact of a continent's longitudinal extent on tropical precipitation",2016,"10.1002/2016GL071518","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85004073268&doi=10.1002%2f2016GL071518&partnerID=40&md5=e832290627feead4da01a7cfffdc112b","We examine how the longitudinal extent of a subtropical continent impacts the distribution of tropical precipitation in two aquaplanet general circulation models. In the simpler model, the addition of land decreases evaporation and precipitation in the hemisphere with the continent, and the precipitation response scales with the continent's extent. In the more comprehensive model, tropical precipitation has zonal variation due to the downstream response of clouds to land. As the continental extent increases, this cloud response weakens and the Intertropical Convergence Zone becomes more zonal and shifts to the continent. The different precipitation responses in the two models indicate the importance of radiative feedbacks in modifying tropical circulation in models. ©2016. American Geophysical Union. All Rights Reserved."
"56714306400;14019399400;7004091561;","Reconciling satellite aerosol optical thickness and surface fine particle mass through aerosol liquid water",2016,"10.1002/2016GL070994","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003875104&doi=10.1002%2f2016GL070994&partnerID=40&md5=be3120bff6e76e406aa6ac1e0324915c","Summertime aerosol optical thickness (AOT) over the southeast U.S. is sharply enhanced over wintertime values. This seasonal pattern is unique and of particular interest because temperatures there have not warmed over the past 100 years. Patterns in surface fine particle mass are inconsistent with satellite reported AOT. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with particle mass measurements at the surface by examining trends in aerosol liquid water (ALW), a particle constituent that scatters radiation and affects satellite AOT but is removed in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIAv2.1 to estimate ALW mass concentrations at Interagency Monitoring of PROtected Visual Environments sites using measured ion mass concentrations and North American Regional Reanalysis meteorological data. Excellent agreement between Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations AOT and estimated ALW provides a plausible explanation for the discrepancies in the geographical patterns of AOT and aerosol mass measurements. ©2016. American Geophysical Union. All Rights Reserved."
"55732558900;9434771700;7202252296;7003666669;55796504300;7401666571;55720018700;55317190600;57190122235;8644195900;","DMS role in ENSO cycle in the tropics",2016,"10.1002/2016JD025333","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003443566&doi=10.1002%2f2016JD025333&partnerID=40&md5=4efbba5772c8e4eeddd04c646bbafe40","We examined the multiyear mean and variability of dimethyl sulfide (DMS) and its relationship to sulfate aerosols, as well as cloud microphysical and radiative properties. We conducted a 150 year simulation using preindustrial conditions produced by the Community Earth System Model embedded with a dynamic DMS module. The model simulated the mean spatial distribution of DMS emissions and burden, as well as sulfur budgets associated with DMS, SO2, H2SO4, and sulfate that were generally similar to available observations and inventories for a variety of regions. Changes in simulated sea-to-air DMS emissions and associated atmospheric abundance, along with associated aerosols and cloud and radiative properties, were consistently dominated by El Niño–Southern Oscillation (ENSO) cycle in the tropical Pacific region. Simulated DMS, aerosols, and clouds showed a weak positive feedback on sea surface temperature. This feedback suggests a link among DMS, aerosols, clouds, and climate on interannual timescales. The variability of DMS emissions associated with ENSO was primarily caused by a higher variation in wind speed during La Niña events. The simulation results also suggest that variations in DMS emissions increase the frequency of La Niña events but do not alter ENSO variability in terms of the standard deviation of the Niño 3 sea surface temperature anomalies. ©2016. American Geophysical Union. All Rights Reserved."
"56900961300;14019342100;9738329300;54420868300;11940701600;6701718885;","Parameterizing total storm conduction currents in the Community Earth System Model",2016,"10.1002/2016JD025376","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003467531&doi=10.1002%2f2016JD025376&partnerID=40&md5=62339675238ae98d9d3039f3c568d6d6","Electrified clouds are known to play a major role in the Global Electric Circuit. These clouds produce upward currents which maintain the potential difference between Earth's surface and the upper atmosphere. In this study, model output from two simulations of the Community Earth System Model (CESM) are compared with conduction currents and other data derived from the Tropical Rainfall Measuring Mission (TRMM) satellite, including both the Lightning Imaging Sensor and Precipitation Radar. The intention is to determine CESM's skill at representing these microphysical and dynamical properties of clouds. Then, these cloud properties are used to develop a model parameterization to compute conduction currents from electrified clouds. Specifically, we evaluate the ability of global mean convective mass flux, ice water path, and convective precipitation to represent conduction current sources. Parameterizations using these variables yield derived global mean currents that agree well with the geographical patterns of TRMM currents. In addition, comparing the diurnal variations of modeled global mean current to the observed diurnal variations of electric potential gradient, root-mean-square (RMS) errors range between 6.5% and 8.1%, but the maximum occurs 4 to 6 h early in all three variables. Output currents derived from the model variables generally match well to the currents derived from TRMM, and the total global current estimates agree well with past studies. This suggests that cloud parameters are well suited for representing the global distribution and strength of currents in a global model framework. ©2016. American Geophysical Union. All Rights Reserved."
"55732558900;9434771700;7202252296;7003666669;55796504300;7401666571;55720018700;55317190600;57190122235;8644195900;","DMS role in ENSO cycle in the tropics",2016,"10.1002/2016JD025333","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029223346&doi=10.1002%2f2016JD025333&partnerID=40&md5=95ddca850af2f39fe2239c4a1b72a880","We examined the multiyear mean and variability of dimethyl sulfide (DMS) and its relationship to sulfate aerosols, as well as cloud microphysical and radiative properties. We conducted a 150 year simulation using preindustrial conditions produced by the Community Earth System Model embedded with a dynamic DMS module. The model simulated the mean spatial distribution of DMS emissions and burden, as well as sulfur budgets associated with DMS, SO2, H2SO4, and sulfate that were generally similar to available observations and inventories for a variety of regions. Changes in simulated sea-to-air DMS emissions and associated atmospheric abundance, along with associated aerosols and cloud and radiative properties, were consistently dominated by El Niño-Southern Oscillation (ENSO) cycle in the tropical Pacific region. Simulated DMS, aerosols, and clouds showed a weak positive feedback on sea surface temperature. This feedback suggests a link among DMS, aerosols, clouds, and climate on interannual timescales. The variability of DMS emissions associated with ENSO was primarily caused by a higher variation in wind speed during La Niña events. The simulation results also suggest that variations in DMS emissions increase the frequency of La Niña events but do not alter ENSO variability in terms of the standard deviation of the Niño 3 sea surface temperature anomalies. © 2016. American Geophysical Union. All Rights Reserved."
"56182620500;7401796996;8629713500;7404829395;7004364155;","A clear-sky radiation closure study using a one-dimensional radiative transfer model and collocated satellite-surface-reanalysis data sets",2016,"10.1002/2016JD025823","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029217409&doi=10.1002%2f2016JD025823&partnerID=40&md5=0507c0d7481c7fe8ba9091ad7efb738b","Earth’s climate is largely determined by the planet’s energy budget, i.e., the balance of incoming and outgoing radiation at the surface and top of atmosphere (TOA). Studies have shown that computing clear-sky radiative fluxes are strongly dependent on atmospheric state variables, such as temperature and water vapor profiles, while the all-sky fluxes are greatly influenced by the presence of clouds. NASA-modeled vertical profiles of temperature and water vapor are used to derive the surface radiation budget from Clouds and Earth Radiant Energy System (CERES), which is regarded as one of the primary sources for evaluating climate change in climate models. In this study, we evaluate the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) reanalyzed clear-sky temperature and water vapor profiles with newly generated atmospheric profiles from Department of Energy Atmospheric Radiation Measurement (ARM)-merged soundings and Aura Microwave Limb Sounder retrievals at three ARM sites. The temperature profiles are well replicated in MERRA-2 at all three sites, whereas tropospheric water vapor is slightly dry below ~700 hPa. These profiles are then used to calculate clear-sky surface and TOA radiative fluxes from the Langley-modified Fu-Liou radiative transfer model (RTM). In order to achieve radiative closure at both the surface and TOA, the ARM-measured surface albedos and aerosol optical depths are adjusted to account for surface inhomogeneity. In general, most of the averaged RTM-calculated surface downward and TOA upward shortwave and longwave fluxes agree within ~5 W/m2 of the observations, which is within the uncertainties of the ARM and CERES measurements. Yet still, further efforts are required to reduce the bias in calculated fluxes in coastal regions. © 2016. American Geophysical Union. All Rights Reserved."
"56182620500;7401796996;8629713500;7404829395;7004364155;","A clear-sky radiation closure study using a one-dimensional radiative transfer model and collocated satellite-surface-reanalysis data sets",2016,"10.1002/2016JD025823","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003674371&doi=10.1002%2f2016JD025823&partnerID=40&md5=8c9410d0691d596c45c93a04c8c94dd1","Earth's climate is largely determined by the planet's energy budget, i.e., the balance of incoming and outgoing radiation at the surface and top of atmosphere (TOA). Studies have shown that computing clear-sky radiative fluxes are strongly dependent on atmospheric state variables, such as temperature and water vapor profiles, while the all-sky fluxes are greatly influenced by the presence of clouds. NASA-modeled vertical profiles of temperature and water vapor are used to derive the surface radiation budget from Clouds and Earth Radiant Energy System (CERES), which is regarded as one of the primary sources for evaluating climate change in climate models. In this study, we evaluate the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) reanalyzed clear-sky temperature and water vapor profiles with newly generated atmospheric profiles from Department of Energy Atmospheric Radiation Measurement (ARM)-merged soundings and Aura Microwave Limb Sounder retrievals at three ARM sites. The temperature profiles are well replicated in MERRA-2 at all three sites, whereas tropospheric water vapor is slightly dry below ~700 hPa. These profiles are then used to calculate clear-sky surface and TOA radiative fluxes from the Langley-modified Fu-Liou radiative transfer model (RTM). In order to achieve radiative closure at both the surface and TOA, the ARM-measured surface albedos and aerosol optical depths are adjusted to account for surface inhomogeneity. In general, most of the averaged RTM-calculated surface downward and TOA upward shortwave and longwave fluxes agree within ~5 W/m2 of the observations, which is within the uncertainties of the ARM and CERES measurements. Yet still, further efforts are required to reduce the bias in calculated fluxes in coastal regions. ©2016. American Geophysical Union. All Rights Reserved."
"55350802700;16308514000;37261739700;56210720700;23491184100;18438062100;16834406100;18134565600;57203776263;6602221672;6603178707;6602356428;7202252296;","Ambient observations of hygroscopic growth factor and f(RH) below 1: Case studies from surface and airborne measurements",2016,"10.1002/2016JD025471","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029222015&doi=10.1002%2f2016JD025471&partnerID=40&md5=8757918f13ea08d8dd33d68493c49bd2","This study reports a detailed set of ambient observations of optical/physical shrinking of particles from exposure to water vapor with consistency across different instruments and regions. Data have been utilized from (i) a shipboard humidified tandem differential mobility analyzer during the Eastern Pacific Emitted Aerosol Cloud Experiment in 2011, (ii) multiple instruments on the NASA DC-8 research aircraft during the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys in 2013, and (iii) the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe during ambient measurements in Tucson, Arizona, during summer 2014 and winter 2015. Hygroscopic growth factor (ratio of humidified-to-dry diameter, GF = Dp,wet/Dp,dry) and f(RH) (ratio of humidified-to-dry scattering coefficients) values below 1 were observed across the range of relative humidity (RH) investigated (75-95%). A commonality of observations of GF and f(RH) below 1 in these experiments was the presence of particles enriched with carbonaceous matter, especially from biomass burning. Evidence of externally mixed aerosol, and thus multiple GFs with at least one GF&lt;1, was observed concurrently with f(RH)&lt;1 during smoke periods. Possible mechanisms responsible for observed shrinkage are discussed and include particle restructuring, volatilization effects, and refractive index modifications due to aqueous processing resulting in optical size modification. To further investigate ambient observations of GFs and f(RH) values less than 1, it is recommended to add an optional prehumidification bypass module to hygroscopicity instruments, to preemptively collapse particles prior to controlled RH measurements. © 2016. American Geophysical Union. All Rights Reserved."
"55350802700;16308514000;37261739700;56210720700;23491184100;18438062100;16834406100;18134565600;57203776263;6602221672;6603178707;6602356428;7202252296;","Ambient observations of hygroscopic growth factor and f(RH) below 1: Case studies from surface and airborne measurements",2016,"10.1002/2016JD025471","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003749433&doi=10.1002%2f2016JD025471&partnerID=40&md5=b24998e7335e55492375bd1720f0c809","This study reports a detailed set of ambient observations of optical/physical shrinking of particles from exposure to water vapor with consistency across different instruments and regions. Data have been utilized from (i) a shipboard humidified tandem differential mobility analyzer during the Eastern Pacific Emitted Aerosol Cloud Experiment in 2011, (ii) multiple instruments on the NASA DC-8 research aircraft during the Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys in 2013, and (iii) the Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe during ambient measurements in Tucson, Arizona, during summer 2014 and winter 2015. Hygroscopic growth factor (ratio of humidified-to-dry diameter, GF = Dp,wet/Dp,dry) and f(RH) (ratio of humidified-to-dry scattering coefficients) values below 1 were observed across the range of relative humidity (RH) investigated (75–95%). A commonality of observations of GF and f(RH) below 1 in these experiments was the presence of particles enriched with carbonaceous matter, especially from biomass burning. Evidence of externally mixed aerosol, and thus multiple GFs with at least one GF &lt; 1, was observed concurrently with f(RH) &lt; 1 during smoke periods. Possible mechanisms responsible for observed shrinkage are discussed and include particle restructuring, volatilization effects, and refractive index modifications due to aqueous processing resulting in optical size modification. To further investigate ambient observations of GFs and f(RH) values less than 1, it is recommended to add an optional prehumidification bypass module to hygroscopicity instruments, to preemptively collapse particles prior to controlled RH measurements. ©2016. American Geophysical Union. All Rights Reserved."
"57211306422;8957403200;55522498000;48361451800;16312351300;37014098900;55995043800;55231577100;","On the relationship between the Madden-Julian Oscillation and 2 m air temperature over central Asia in boreal winter",2016,"10.1002/2016JD025651","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003678459&doi=10.1002%2f2016JD025651&partnerID=40&md5=2058bbdea815867d0ec004a64b550643","Linear regression is used to explore the relationship between the Madden-Julian oscillation (MJO) and 2 m air temperature (T2M) over central Asia in boreal winter during 1979–2012. During MJO phases 3 and 4 (7 and 8), T2M anomalies exhibit a significantly strong, negative (positive) response to the MJO from the Arabian Sea to northwestern China. The anomalies of T2M are essentially influenced by surface net downward long (Ldown) and shortwave radiations, which are caused by the changes in total cloud cover (TCC) and low-level tropospheric air temperature. The anomalies of Ldown that are caused by TCC account for 20–65% of total Ldown. The remaining anomalies of total Ldown are explained by low-level air temperature changes. The 850 hPa air temperature (T850) tendency is mainly affected by the vertical motion over central Asia during MJO phases 1, 2, 4–6, and 8, as well as over northern India during phases 3 and 7. Over Saudi Arabia, Afghanistan, Pakistan, Kazakhstan, and northwestern China, the anomalies of T850 tendency are mainly explained by the temperature advection during phases 3 and 7. TCC and vertical motion are affected by the evolution of the MJO event. The cyclonic (anticyclonic) circulation related to the MJO over central Asia during phases 3 and 4 (7 and 8) causes the transport of cold (warm) air over central Asia. The MJO can be a useful intraseasonal signal to predict winter T2M over central Asia, where temperatures would be colder (warmer) than normal during MJO phases 3 and 4 (7 and 8). ©2016. The Authors."
"23392868000;7005920812;","Parameterizing microphysical effects on variances and covariances of moisture and heat content using a multivariate probability density function: A study with CLUBB (tag MVCS)",2016,"10.5194/gmd-9-4273-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84998812071&doi=10.5194%2fgmd-9-4273-2016&partnerID=40&md5=3b8f3b43f6cbebad9da3ec8606a93ca8","Microphysical processes, such as the formation, growth, and evaporation of precipitation, interact with variability and covariances (e.g., fluxes) in moisture and heat content. For instance, evaporation of rain may produce cold pools, which in turn may trigger fresh convection and precipitation. These effects are usually omitted or else crudely parameterized at subgrid scales in weather and climate models.<br><br>A more formal approach is pursued here, based on predictive, horizontally averaged equations for the variances, covariances, and fluxes of moisture and heat content. These higher-order moment equations contain microphysical source terms. The microphysics terms can be integrated analytically, given a suitably simple warm-rain microphysics scheme and an approximate assumption about the multivariate distribution of cloud-related and precipitation-related variables. Performing the integrations provides exact expressions within an idealized context.<br><br>A large-eddy simulation (LES) of a shallow precipitating cumulus case is performed here, and it indicates that the microphysical effects on (co)variances and fluxes can be large. In some budgets and altitude ranges, they are dominant terms. The analytic expressions for the integrals are implemented in a single-column, higher-order closure model. Interactive single-column simulations agree qualitatively with the LES. The analytic integrations form a parameterization of microphysical effects in their own right, and they also serve as benchmark solutions that can be compared to non-Analytic integration methods. © Author(s) 2016. CC Attribution 3.0 License."
"35221443100;57196309273;7501627905;","Radiative effects of interannually varying vs. interannually invariant aerosol emissions from fires",2016,"10.5194/acp-16-14495-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85001950290&doi=10.5194%2facp-16-14495-2016&partnerID=40&md5=35bd4839a34c1ac012fc1a0307caaada","Open-burning fires play an important role in the earth's climate system. In addition to contributing a substantial fraction of global emissions of carbon dioxide, they are a major source of atmospheric aerosols containing organic carbon, black carbon, and sulfate. These ""fire aerosols"" can influence the climate via direct and indirect radiative effects. In this study, we investigate these radiative effects and the hydrological fast response using the Community Atmosphere Model version 5 (CAM5). Emissions of fire aerosols exert a global mean net radiative effect of -1.0 W m-2, dominated by the cloud shortwave response to organic carbon aerosol. The net radiative effect is particularly strong over boreal regions. Conventionally, many climate modelling studies have used an interannually invariant monthly climatology of emissions of fire aerosols. However, by comparing simulations using interannually varying emissions vs. interannually invariant emissions, we find that ignoring the interannual variability of the emissions can lead to systematic overestimation of the strength of the net radiative effect of the fire aerosols. Globally, the overestimation is +23 % (-0.2 W m-2). Regionally, the overestimation can be substantially larger. For example, over Australia and New Zealand the overestimation is +58 % (-1.2 W m-2), while over Boreal Asia the overestimation is +43 % (-1.9 W m-2). The systematic overestimation of the net radiative effect of the fire aerosols is likely due to the non-linear influence of aerosols on clouds. However, ignoring interannual variability in the emissions does not appear to significantly impact the hydrological fast response. In order to improve understanding of the climate system, we need to take into account the interannual variability of aerosol emissions. © 2016. CC Attribution 3.0 License."
"57192179473;7004587644;7202802701;16643352100;24780091900;7004272801;","Assessing the sensitivity of the hydroxyl radical to model biases in composition and temperature using a single-column photochemical model for Lauder, New Zealand",2016,"10.5194/acp-16-14599-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84999634762&doi=10.5194%2facp-16-14599-2016&partnerID=40&md5=a949f69230757f8714e4d43c4a1bb77d","We assess the major factors contributing to local biases in the hydroxyl radical (OH) as simulated by a global chemistry-climate model, using a single-column photochemical model (SCM) analysis. The SCM has been constructed to represent atmospheric chemistry at Lauder, New Zealand, which is representative of the background atmosphere of the Southern Hemisphere (SH) mid-latitudes. We use long-term observations of variables essential to tropospheric OH chemistry, i.e. ozone (O3), water vapour (H2O), methane (CH4), carbon monoxide (CO), and temperature, and assess how using these measurements affect OH calculated in the SCM, relative to a reference simulation only using modelled fields. The analysis spans 1994 to 2010. Results show that OH responds approximately linearly to correcting biases in O3, H2O, CO, CH4, and temperature. The biggest impact on OH is due to correcting an overestimation by approximately 20 to 60% of H2O, using radiosonde observations. Correcting this moist bias leads to a reduction of OH by around 5 to 35%. This is followed by correcting predominantly overestimated O3. In the troposphere, the model biases are mostly in the range of -10 to 30%. The impact of changing O3 on OH is due to two pathways; the OH responses to both are of similar magnitude but different seasonality: correcting in situ tropospheric ozone leads to changes in OH in the range -14 to 4%, whereas correcting the photolysis rate of O3 in accordance with overhead column ozone changes leads to increases of OH of 8 to 16%. The OH sensitivities to correcting CH4, CO, and temperature biases are all minor effects. The work demonstrates the feasibility of quantitatively assessing OH sensitivity to biases in longer-lived species, which can help explain differences in simulated OH between global chemistry models and relative to observations. In addition to clear-sky simulations, we have performed idealized sensitivity simulations to assess the impact of clouds (ice and liquid) on OH. The results indicate that the impacts on the ozone photolysis rate and OH are substantial, with a general decrease of OH below the clouds of up to 30% relative to the clear-skies situation, and an increase of up to 15% above. Using the SCM simulation we calculate recent OH trends at Lauder. For the period of 1994 to 2010, all trends are insignificant, in agreement with previous studies. For example, the trend in total-column OH is 0.5 ± 1.3% over this period."
"7003800456;35338710200;55519833300;57190047135;57190048278;8263760800;","Impact of stratospheric volcanic aerosols on age-of-air and transport of long-lived species",2016,"10.3390/atmos7110149","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85000783183&doi=10.3390%2fatmos7110149&partnerID=40&md5=9f8900f7e4fbdee94b1886da8bd9d4cc","The radiative perturbation associated to stratospheric aerosols from major explosive volcanic eruptions may induce significant changes in stratospheric dynamics. The aerosol heating rates warm up the lower stratosphere and cause a westerly wind anomaly, with additional tropical upwelling. Large scale transport of stratospheric trace species may be perturbed as a consequence of this intensified Brewer-Dobson circulation. The radiatively forced changes of the stratospheric circulation during the first two years after the eruption of Mt. Pinatubo (June 1991) may help explain the observed trend decline of long-lived greenhouse gases at surface stations (approximately -8 and -0.4 ppbv/year for CH4 and N2O, respectively). This decline is partly driven by the increased mid- to high-latitude downward flux at the tropopause and also by an increased isolation of the tropical pipe in the vertical layer near the tropopause, with reduced horizontal eddy mixing. Results from a climate-chemistry coupled model are shown for both long-lived trace species and the stratospheric age-of-air. The latter results to be younger by approximately 0.5 year at 30 hPa for 3-4 years after the June 1991 Pinatubo eruption, as a result of the volcanic aerosols radiative perturbation and is consistent with independent estimates based on long time series of in situ profile measurements of SF6 and CO2. Younger age of air is also calculated after Agung, El Chichón and Ruiz eruptions, as well as negative anomalies of the N2O growth rate at the extratropical tropopause layer. This type of analysis is made comparing the results of two ensembles of model simulations (1960-2005), one including stratospheric volcanic aerosols and their radiative interactions and a reference case where the volcanic aerosols do not interact with solar and planetary radiation.. © 2016 by the authors."
"35337868700;7004091561;6603497236;7103002964;55957764500;55256235500;36647693000;7402781278;55668807600;8585525800;7005002049;","Identifying precursors and aqueous organic aerosol formation pathways during the SOAS campaign",2016,"10.5194/acp-16-14409-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84997605184&doi=10.5194%2facp-16-14409-2016&partnerID=40&md5=d256d0b4036b5c72357c02f4557b8231","Aqueous multiphase chemistry in the atmosphere can lead to rapid transformation of organic compounds, forming highly oxidized, low-volatility organic aerosol and, in some cases, light-Absorbing (brown) carbon. Because liquid water is globally abundant, this chemistry could substantially impact climate, air quality, and health. Gas-phase precursors released from biogenic and anthropogenic sources are oxidized and fragmented, forming water-soluble gases that can undergo reactions in the aqueous phase (in clouds, fogs, and wet aerosols), leading to the formation of secondary organic aerosol (SOAAQ). Recent studies have highlighted the role of certain precursors like glyoxal, methylglyoxal, glycolaldehyde, acetic acid, acetone, and epoxides in the formation of SOAAQ. The goal of this work is to identify additional precursors and products that may be atmospherically important. In this study, ambient mixtures of water-soluble gases were scrubbed from the atmosphere into water at Brent, Alabama, during the 2013 Southern Oxidant and Aerosol Study (SOAS). Hydroxyl (OHĝš) radical oxidation experiments were conducted with the aqueous mixtures collected from SOAS to better understand the formation of SOA through gas-phase followed by aqueous-phase chemistry. Total aqueous-phase organic carbon concentrations for these mixtures ranged from 92 to 179ĝ€μM-C, relevant for cloud and fog waters. Aqueous OH-reactive compounds were primarily observed as odd ions in the positive ion mode by electrospray ionization mass spectrometry (ESI-MS). Ultra high-resolution Fourier-Transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) spectra and tandem MS (MS-MS) fragmentation of these ions were consistent with the presence of carbonyls and tetrols. Products were observed in the negative ion mode and included pyruvate and oxalate, which were confirmed by ion chromatography. Pyruvate and oxalate have been found in the particle phase in many locations (as salts and complexes). Thus, formation of pyruvate/oxalate suggests the potential for aqueous processing of these ambient mixtures to form SOAAQ. © Author(s) 2016."
"55547120851;9232771700;55103352400;36471608600;56047465400;57207269279;","Improvement of cold flow properties of Cocos nucifera and Calophyllum inophyllum biodiesel blends using polymethyl acrylate additive",2016,"10.1016/j.jclepro.2016.07.080","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991104777&doi=10.1016%2fj.jclepro.2016.07.080&partnerID=40&md5=3eaea2cb5f88a52965d496d93ac14e9f","Biodiesel, which comprises of fatty acid esters, is an alternative fuel for diesel engines. However, biodiesel has poorer cold flow properties (CFPs; i.e., cloud point (CP), cold filter plugging point (CFPP), and pour point (PP)) than diesel fuel. This study aims to reduce the PP, CFPP, and CP of two different biodiesels, namely, Cocos nucifera (coconut) and Calophyllum inophyllum (C. inophyllum), using polymethyl acrylate (PMA) additives. This study also investigates the effect of PMA on other biodiesel properties. Various physicochemical properties were measured and compared with the ASTM D6751 and EN14214 standards. Differential scanning calorimetry was used to observe the crystal behavior of the biodiesel blends. Results showed that 20% of biodiesel blended with diesel (B20) and 0.03 wt% of PMA showed the highest improvement in the CP, PP, and CFPP. This study also investigates the influence of PMA on oxidation stability, flash point, heating value, and kinematic viscosity. These properties of B20 satisfy the ASTM D6751 and EN14214 standards. The process of crystal aggrandizement and the rate of wax crystal precipitation of B20 can be modified by PMA, resulting in enhanced CFPs of the biodiesel blend. Therefore, PMA is an effective cold-flow-improving additive for coconut-based and C. inophyllum-based biodiesel blends. Moreover, the results indicated that 20% coconut and C. inophyllum biodiesel blends with 0.03 wt% of PMA can be used in cold climate areas without any problem in terms of fuel physicochemical quality. © 2016 Elsevier Ltd"
"57033751200;35566999200;","Surface energy balance sensitivity to meteorological variability on Haig Glacier, Canadian Rocky Mountains",2016,"10.5194/tc-10-2799-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996635665&doi=10.5194%2ftc-10-2799-2016&partnerID=40&md5=b149c0a1c0d17ad807ab76fb7fe38b19","Energy exchanges between the atmosphere and the glacier surface control the net energy available for snow and ice melt. This paper explores the response of a midlatitude glacier in the Canadian Rocky Mountains to daily and interannual variations in the meteorological parameters that govern the surface energy balance. We use an energy balance model to run sensitivity tests to perturbations in temperature, specific humidity, wind speed, incoming shortwave radiation, glacier surface albedo, and winter snowpack depth. Variables are perturbed (i) in isolation, (ii) including internal feedbacks, and (iii) with co-evolution of meteorological perturbations, derived from the North American regional climate reanalysis (NARR) over the period 1979-2014. Summer melt at this site has the strongest sensitivity to interannual variations in temperature, albedo, and specific humidity, while fluctuations in cloud cover, wind speed, and winter snowpack depth have less influence. Feedbacks to temperature forcing, in particular summer albedo evolution, double the melt sensitivity to a temperature change. When meteorological perturbations covary through the NARR forcing, summer temperature anomalies remain important in driving interannual summer energy balance and melt variability, but they are reduced in importance relative to an isolated temperature forcing. Covariation of other variables (e.g., clear skies, giving reduced incoming longwave radiation) may be partially compensating for the increase in temperature. The methods introduced in this paper provide a framework that can be extended to compare the sensitivity of glaciers in different climate regimes, e.g., polar, maritime, or tropical environments, and to assess the importance of different meteorological parameters in different regions. © Author(s) 2016."
"57217911076;56033070100;26643041500;7102963655;26422498700;57207261095;24446327700;25825715600;23051160600;57192064212;7006960661;35461255500;","Observational evidence for aerosols increasing upper tropospheric humidity",2016,"10.5194/acp-16-14331-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996587467&doi=10.5194%2facp-16-14331-2016&partnerID=40&md5=b1c9aad6b5ececcf3913e8c8e394de72","Aerosol-cloud interactions are the largest source of uncertainty in the radiative forcing of the global climate. A phenomenon not included in the estimates of the total net forcing is the potential increase in upper tropospheric humidity (UTH) by anthropogenic aerosols via changes in the microphysics of deep convection. Using remote sensing data over the ocean east of China in summer, we show that increased aerosol loads are associated with an UTH increase of 2.2 ± 1.5 in units of relative humidity. We show that humidification of aerosols or other meteorological covariation is very unlikely to be the cause of this result, indicating relevance for the global climate. In tropical moist air such an UTH increase leads to a regional radiative effect of 0.5 ± 0.4 W m-2. We conclude that the effect of aerosols on UTH should be included in future studies of anthropogenic climate change and climate sensitivity. © Author(s) 2016."
"55405340400;36059595100;7005920812;56919006400;35768521600;7003666669;","Vertical overlap of probability density functions of cloud and precipitation hydrometeors",2016,"10.1002/2016JD025158","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84997194308&doi=10.1002%2f2016JD025158&partnerID=40&md5=e93c5f2724e521817c371b121b973f26","Coarse-resolution climate models increasingly rely on probability density functions (PDFs) to represent subgrid-scale variability of prognostic variables. While PDFs characterize the horizontal variability, a separate treatment is needed to account for the vertical structure of clouds and precipitation. When subcolumns are drawn from these PDFs for microphysics or radiation parameterizations, appropriate vertical correlations must be enforced via PDF overlap specifications. This study evaluates the representation of PDF overlap in the Subgrid Importance Latin Hypercube Sampler (SILHS) employed in the assumed PDF turbulence and cloud scheme called the Cloud Layers Unified by Binormals (CLUBB). PDF overlap in CLUBB-SILHS simulations of continental and tropical oceanic deep convection is compared with overlap of PDF of various microphysics variables in cloud-resolving model (CRM) simulations of the same cases that explicitly predict the 3-D structure of cloud and precipitation fields. CRM results show that PDF overlap varies significantly between different hydrometeor types, as well as between PDFs of mass and number mixing ratios for each species-a distinction that the current SILHS implementation does not make. In CRM simulations that explicitly resolve cloud and precipitation structures, faster falling species, such as rain and graupel, exhibit significantly higher coherence in their vertical distributions than slow falling cloud liquid and ice. These results suggest that to improve the overlap treatment in the subcolumn generator, the PDF correlations need to depend on hydrometeor properties, such as fall speeds, in addition to the currently implemented dependency on the turbulent convective length scale. © 2016. American Geophysical Union. All Rights Reserved."
"54399869900;7401836526;","Narrowing of the ITCZ in a warming climate: Physical mechanisms",2016,"10.1002/2016GL070396","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84998706967&doi=10.1002%2f2016GL070396&partnerID=40&md5=0e92294fd28f7e9523ca2418b5fdc2bd","The Intertropical Convergence Zone (ITCZ) narrows in response to global warming in both observations and climate models. However, a physical understanding of this narrowing is lacking. Here we show that the narrowing of the ITCZ in simulations of future climate is related to changes in the moist static energy (MSE) budget. MSE advection by the mean circulation and MSE divergence by transient eddies tend to narrow the ITCZ, while changes in net energy input to the atmosphere and the gross moist stability tend to widen the ITCZ. The narrowing tendency arises because the meridional MSE gradient strengthens with warming, whereas the largest widening tendency is due to increasing shortwave heating of the atmosphere. The magnitude of the ITCZ narrowing depends strongly on the gross moist stability and clouds, emphasizing the need to better understand these fundamental processes in the tropical atmosphere. ©2016. American Geophysical Union. All Rights Reserved."
"8658386900;37018824600;57198616562;35478813200;34881780600;6701754792;7406215388;57204253860;7102866124;","Convective cloud vertical velocity and mass-flux characteristics from radar wind profiler observations during GoAmazon2014/5",2016,"10.1002/2016JD025303","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84999836812&doi=10.1002%2f2016JD025303&partnerID=40&md5=8d475b4889098a27a6a57bf4404b13e8","A radar wind profiler data set collected during the 2 year Department of Energy Atmospheric Radiation Measurement Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) campaign is used to estimate convective cloud vertical velocity, area fraction, and mass flux profiles. Vertical velocity observations are presented using cumulative frequency histograms and weighted mean profiles to provide insights in a manner suitable for global climate model scale comparisons (spatial domains from 20 km to 60 km). Convective profile sensitivity to changes in environmental conditions and seasonal regime controls is also considered. Aggregate and ensemble average vertical velocity, convective area fraction, and mass flux profiles, as well as magnitudes and relative profile behaviors, are found consistent with previous studies. Updrafts and downdrafts increase in magnitude with height to midlevels (6 to 10 km), with updraft area also increasing with height. Updraft mass flux profiles similarly increase with height, showing a peak in magnitude near 8 km. Downdrafts are observed to be most frequent below the freezing level, with downdraft area monotonically decreasing with height. Updraft and downdraft profile behaviors are further stratified according to environmental controls. These results indicate stronger vertical velocity profile behaviors under higher convective available potential energy and lower low-level moisture conditions. Sharp contrasts in convective area fraction and mass flux profiles are most pronounced when retrievals are segregated according to Amazonian wet and dry season conditions. During this deployment, wet season regimes favored higher domain mass flux profiles, attributed to more frequent convection that offsets weaker average convective cell vertical velocities. © 2016. American Geophysical Union. All Rights Reserved."
"7201784177;28367935500;","Land dominates the regional response to CO2 direct radiative forcing",2016,"10.1002/2016GL071368","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84998692540&doi=10.1002%2f2016GL071368&partnerID=40&md5=36e9ec13f0485329ee63d3811ca2ad9b","In Atmospheric General Circulation Models (AGCMs) direct radiative forcing (increased CO2 with fixed sea surface temperature) is an imperfect concept because land temperatures are not fixed. Here the response to direct radiative forcing is decomposed into increased CO2 over ocean and land using an AGCM with spatially dependent CO2. The land versus ocean response is mostly linear. Consistent with previous work, ocean direct radiative forcing decreases ocean-averaged outgoing longwave radiation, precipitation, and tropical circulation intensity; however, it cannot explain the regional response to direct radiative forcing. Increased CO2 over land dominates the regional response via energy input over land, e.g., over deserts where there is no cloud and water vapor masking and a Rossby wave teleconnection. This mechanism operates across a range of climate perturbations, including decreased CO2. Previous AGCM decompositions involving direct radiative forcing and indirect sea surface temperature warming must be reinterpreted to include the importance of increased CO2 over land. ©2016. The Authors."
"57190215031;14421017500;55567649200;35113492400;35849722200;18134578100;56300205000;","Parameterization and comparative evaluation of the CCN number concentration on Mt. Huang, China",2016,"10.1016/j.atmosres.2016.07.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978427788&doi=10.1016%2fj.atmosres.2016.07.004&partnerID=40&md5=3b6e129d509578e0c61500028db484da","Quantifying regional CCN concentration is important for reliable estimations of aerosol indirect effects. Based on observational data of the number concentrations of total aerosol (NCN) and cloud condensation nuclei (NCCN), particle number size distribution (PNSD) and, size-resolved activation ratio (SRAR) obtained on Mt. Huang in southeast China from September 19 to October 11, 2012, seven parameterization schemes are used to calculate NCCN employing CCN spectra, bulk activation ratio, cut-off diameter and SRAR. The calculations and the observations are compared and analyzed at four supersaturations (S) from 0.109% to 0.67%. Results show that (1) the parameterization using the average cut-off diameter Dm, which is derived from the various measured PNSD and NCCN, provides the best estimate of NCCN, with coefficient of determination, R2 = 0.70–0.90 and NCCN,cal/NCCN,obs = 0.92–1.11, followed by the method of combining an average size-resolved activation curve with the PNSD, with R2 = 0.71–0.91 and NCCN,cal/NCCN,obs = 0.71–0.91; average D50 together with the PNSD also provides a rational scheme for NCCN prediction, with NCCN,cal/NCCN,obs = 0.86–0.94 and R2 = 0.70–0.89; (2) the method of parameterizing CCN spectra, though straightforward, has limits under polluted conditions. Reasonable NCCN estimate could only be obtained at high S (R2 ≥ 0.85 at S = 0.39% and 0.67%). (3) For the method employing the bulk activation ratio ARB(S), NCCN are substantially overestimated by using total mode-based ARB(S) (NCCN,cal/NCCN,obs = 0.94–1.39, R2 = 0.17–0.67), while applying ammonium sulfate-based ARB(S) yields improved CCN predictions (NCCN,cal/NCCN,obs = 0.91–1.11, R2 = 0.70–0.91). In southern China, when determining the parameterization schemes in climate models, it is first recommended to use the method of average cut-off diameter or SRAR, with the various measured PNSD to predict NCCN. Besides, the method using ammonium sulfate-based ARB(S) and parameterizing CCN spectra also provides a viable way to calculate NCCN. © 2016 Elsevier B.V."
"6506644040;47461006200;54890344200;","Surface energy exchange in a tropical montane cloud forest environment: Flux partitioning, and seasonal and land cover-related variations",2016,"10.1016/j.agrformet.2016.06.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976902801&doi=10.1016%2fj.agrformet.2016.06.011&partnerID=40&md5=39e809dd2f969e5e3d678142d0e3737c","Relationships between seasonal climate, land cover and surface energy exchange in tropical montane cloud forest environments are poorly understood. The goal of this study was to investigate the seasonality of flux partitioning in lower montane cloud forest (LMCF), shaded coffee (CO) and sugarcane (SU) in central Veracruz, Mexico, as well as to evaluate the changes in surface energy exchange associated with the conversion of LMCF to CO or SU. Sensible (H) and latent heat (λE) fluxes were measured during the late dry and wet seasons using eddy covariance (CO and SU) and sap flow (LMCF) methods. Other measurements included: meteorological parameters, radiation balance, soil heat flux, soil moisture and vegetation characteristics. During the wet-season month of July, average midday Bowen ratios (βs) for sunny conditions were lowest and least variable among land covers: 0.4 ± 0.2 (SE) in LMCF, 0.5 ± 0.1 in SU and 0.7 ± 0.1 in CO. In contrast, during the late dry-season months of March and April, βs were higher (i.e. higher H and lower λE) and more variable. The highest values of β were observed in LMCF, reflecting effects of partial leaf-shedding by dominant deciduous species (2.4 ± 0.8, March) and increased stomatal control (1.4 ± 0.3, April). There was also evidence of stomatal limitation of λE in CO and SU, having βs of up to 1.0 ± 0.1 in April and March, respectively. As compared to LMCF, the average midday available energy (Ae) for sunny conditions was very similar in CO (−3 ± 7%) and 15 ± 8% lower in SU. Although not all results were statistically significant, they suggest that for the wet season conversion of LMCF to shaded coffee or sugarcane led to a decrease of 15 ± 14% or 15 ± 17% in midday λE under sunny conditions, respectively, whereas corresponding values of H increased by 37 ± 38% or remained about the same (−4 ± 40%). In contrast, for the late dry season, conversion of LMCF to shaded coffee or sugarcane appears to have resulted in higher λE and lower H, with changes of, respectively, +79 (±32)%/–45 (±16)% (CO) or +39 (±32)%/–43 (±16)% (SU) for a partially leafless LMCF in March, and +17 (±16)%/–11 (±16)% (CO) for a fully-leafed LMCF in April. In order to more accurately quantify the changes in surface energy fluxes associated with LMCF conversion, future work should focus on reducing the errors in the flux estimates. Nevertheless, for sunny days during the wet season, potential changes in the moisture and heat content of the local atmosphere due to the conversion of LMCF to CO or SU seem to have been in the same direction as those induced by increased greenhouse gases (drying and warming), whereas for the late dry season the effects appear to have been opposite (moistening and cooling). © 2016 Elsevier B.V."
"55331840500;49963597700;57203259838;7003386176;","Are eruptions from linear fissures and caldera ring dykes more likely to produce pyroclastic flows?",2016,"10.1016/j.epsl.2016.09.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989809171&doi=10.1016%2fj.epsl.2016.09.005&partnerID=40&md5=ffd5530726dadc9e5793ae170ee5da69","Turbulent volcanic jets are produced by highly-energetic explosive eruptions and may form buoyant plumes that rise many tens of kilometres into the atmosphere to form umbrella clouds or collapse to generate ground-hugging pyroclastic flows. Ash injected into the atmosphere can be transported for many hundreds of kilometres with the potential to affect climate, disrupt global air travel and cause respiratory health problems. Pyroclastic flows, by contrast, are potentially catastrophic to populations and infrastructure close to the volcano. Key to which of these two behaviours will occur is the extent to which the mechanical entrainment and mixing of ambient air into the jet by large (entraining) eddies forming the jet edge changes the density of the air–ash mixture: low entrainment rates lead to pyroclastic flows and high entrainment rates give rise to buoyant plumes. Recent experiments on particle-laden (multi-phase) volcanic jets from flared and straight-sided circular openings suggest that the likelihood for buoyant plumes will depend strongly on the shape and internal geometry of the vent region. This newly recognised sensitivity of the fate of volcanic jets to the structure of the vent is a consequence of a complex dynamic coupling between the jet and entrained solid particles, an effect that has generally been overlooked in previous studies. Building on this work, here we use an extensive series of experiments on multi-phase turbulent jets from analogue linear fissures and annular ring fractures to explore whether the restrictive vent geometry during cataclysmic caldera-forming (CCF) eruptions will ultimately lead a relatively greater frequency of pyroclastic flows than eruptions from circular vents on stratovolcanoes. Our results, understood through scaling analyses and a one-dimensional theoretical model, show that entrainment is enhanced where particle motions contribute angular momentum to entraining eddies. However, because the size of the entraining eddies scales approximately with vent width, the extent of entrainment is reduced as the vent width becomes small in comparison to its length. Consequently, our work shows that for specified mass eruption rates, the high length-to-width ratio vents typical of CCF events are more likely to produce pyroclastic flows. We suggest that the enigmatic trend in the geological record for the largest CCF eruptions to produce pyroclastic flows is an expected consequence of their being erupted through continuous or piece-wise continuous caldera ring fractures. © 2016 Elsevier B.V."
"57188742108;36465124400;7006235542;21933618400;7006377579;57195257572;57191958168;6701905330;56033201200;56919576300;6602087140;55454856700;23486614500;9043417100;57189089842;37089603000;24537168200;55783064400;55730541100;7201787800;","Observed microphysical changes in Arctic mixed-phase clouds when transitioning from sea ice to open ocean",2016,"10.5194/acp-16-13945-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995538961&doi=10.5194%2facp-16-13945-2016&partnerID=40&md5=b085387f3b4d4c4d183f6fff5912dddd","In situ airborne observations of cloud microphysics, aerosol properties, and thermodynamic structure over the transition from sea ice to ocean are presented from the Aerosol-Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) campaign. A case study from 23 March 2013 provides a unique view of the cloud microphysical changes over this transition under cold-air outbreak conditions. Cloud base lifted and cloud depth increased over the transition from sea ice to ocean. Mean droplet number concentrations, Ndrop, also increased from 110 ± 36 cm-3 over the sea ice to 145 ± 54 cm-3 over the marginal ice zone (MIZ). Downstream over the ocean, Ndrop decreased to 63 ± 30 cm-3. This reduction was attributed to enhanced collision-coalescence of droplets within the deep ocean cloud layer. The liquid water content increased almost four fold over the transition and this, in conjunction with the deeper cloud layer, allowed rimed snowflakes to develop and precipitate out of cloud base downstream over the ocean. The ice properties of the cloud remained approximately constant over the transition. Observed ice crystal number concentrations averaged approximately 0.5-1.5 L-1, suggesting only primary ice nucleation was active; however, there was evidence of crystal fragmentation at cloud base over the ocean. Little variation in aerosol particle number concentrations was observed between the different surface conditions; however, some variability with altitude was observed, with notably greater concentrations measured at higher altitudes (&gt; 800 m) over the sea ice. Near-surface boundary layer temperatures increased by 13 °C from sea ice to ocean, with corresponding increases in surface heat fluxes and turbulent kinetic energy. These significant thermodynamic changes were concluded to be the primary driver of the microphysical evolution of the cloud. This study represents the first investigation, using in situ airborne observations, of cloud microphysical changes with changing sea ice cover and addresses the question of how the microphysics of Arctic stratiform clouds may change as the region warms and sea ice extent reduces. © Author(s) 2016."
"10139397300;26867472700;36894599500;6602414959;24390528000;56604012500;6602988199;14630194200;37090362900;6602600408;7003777747;","Regional and seasonal radiative forcing by perturbations to aerosol and ozone precursor emissions",2016,"10.5194/acp-16-13885-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975029792&doi=10.5194%2facp-16-13885-2016&partnerID=40&md5=aa51c2646354cc3d3269739ff6c0a8c9","Predictions of temperature and precipitation responses to changes in the anthropogenic emissions of climate forcers require the quantification of the radiative forcing exerted by those changes. This task is particularly difficult for near-term climate forcers like aerosols, methane, and ozone precursors because their short atmospheric lifetimes cause regionally and temporally inhomogeneous radiative forcings. This study quantifies specific radiative forcing, defined as the radiative forcing per unit change in mass emitted, for eight near-term climate forcers as a function of their source regions and the season of emission by using dedicated simulations by four general circulation and chemistry-transport models. Although differences in the representation of atmospheric chemistry and radiative processes in different models impede the creation of a uniform dataset, four distinct findings can be highlighted. Firstly, specific radiative forcing for sulfur dioxide and organic carbon are stronger when aerosol-cloud interactions are taken into account. Secondly, there is a lack of agreement on the sign of the specific radiative forcing of volatile organic compound perturbations, suggesting they are better avoided in climate mitigation strategies. Thirdly, the strong seasonalities of the specific radiative forcing of most forcers allow strategies to minimise positive radiative forcing based on the timing of emissions. Finally, European and shipping emissions exert stronger aerosol specific radiative forcings compared to East Asia where the baseline is more polluted. This study can therefore form the basis for further refining climate mitigation options based on regional and seasonal controls on emissions. For example, reducing summertime emissions of black carbon and wintertime emissions of sulfur dioxide in the more polluted regions is a possible way to improve air quality without weakening the negative radiative forcing of aerosols."
"57190946513;57191890705;35311447300;7004049712;57204288222;","Particle size traces modern Saharan dust transport and deposition across the equatorial North Atlantic",2016,"10.5194/acp-16-13697-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979086024&doi=10.5194%2facp-16-13697-2016&partnerID=40&md5=521135f3cbf3e21b7b4e893d8b855fa8","Mineral dust has a large impact on regional and global climate, depending on its particle size. Especially in the Atlantic Ocean downwind of the Sahara, the largest dust source on earth, the effects can be substantial but are poorly understood. This study focuses on seasonal and spatial variations in particle size of Saharan dust deposition across the Atlantic Ocean, using an array of submarine sediment traps moored along a transect at 12°N. We show that the particle size decreases downwind with increased distance from the Saharan source, due to higher gravitational settling velocities of coarse particles in the atmosphere. Modal grain sizes vary between 4 and 32 μm throughout the different seasons and at five locations along the transect. This is much coarser than previously suggested and incorporated into climate models. In addition, seasonal changes are prominent, with coarser dust in summer and finer dust in winter and spring. Such seasonal changes are caused by transport at higher altitudes and at greater wind velocities during summer than in winter. Also, the latitudinal migration of the dust cloud, associated with the Intertropical Convergence Zone, causes seasonal differences in deposition as the summer dust cloud is located more to the north and more directly above the sampled transect. Furthermore, increased precipitation and more frequent dust storms in summer coincide with coarser dust deposition. Our findings contribute to understanding Saharan dust transport and deposition relevant for the interpretation of sedimentary records for climate reconstructions, as well as for global and regional models for improved prediction of future climate. © 2016 The Author(s)."
"55329113100;6602182223;57208121852;","Effect of aerosol subgrid variability on aerosol optical depth and cloud condensation nuclei: Implications for global aerosol modelling",2016,"10.5194/acp-16-13619-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994841555&doi=10.5194%2facp-16-13619-2016&partnerID=40&md5=284a31ba565a17f334c3320de8538d53","A fundamental limitation of grid-based models is their inability to resolve variability on scales smaller than a grid box. Past research has shown that significant aerosol variability exists on scales smaller than these grid boxes, which can lead to discrepancies in simulated aerosol climate effects between high- and low-resolution models. This study investigates the impact of neglecting subgrid variability in present-day global microphysical aerosol models on aerosol optical depth (AOD) and cloud condensation nuclei (CCN). We introduce a novel technique to isolate the effect of aerosol variability from other sources of model variability by varying the resolution of aerosol and trace gas fields while maintaining a constant resolution in the rest of the model. <br><br> We compare WRF-Chem (Weather and Research Forecast model) runs in which aerosol and gases are simulated at 80ĝ€km and again at 10ĝ€km resolutions; in both simulations the other model components, such as meteorology and dynamics, are kept at the 10ĝ€km baseline resolution. We find that AOD is underestimated by 13ĝ€% and CCN is overestimated by 27ĝ€% when aerosol and gases are simulated at 80ĝ€km resolution compared to 10ĝ€km. The processes most affected by neglecting aerosol subgrid variability are gas-phase chemistry and aerosol uptake of water through aerosol-gas equilibrium reactions. The inherent non-linearities in these processes result in large changes in aerosol properties when aerosol and gaseous species are artificially mixed over large spatial scales. These changes in aerosol and gas concentrations are exaggerated by convective transport, which transports these altered concentrations to altitudes where their effect is more pronounced. These results demonstrate that aerosol variability can have a large impact on simulating aerosol climate effects, even when meteorology and dynamics are held constant. Future aerosol model development should focus on accounting for the effect of subgrid variability on these processes at global scales in order to improve model predictions of the aerosol effect on climate. © Author(s) 2016."
"7006766881;7003976079;56442691300;","The transformation of Arctic clouds with warming",2016,"10.1007/s10584-016-1772-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984846221&doi=10.1007%2fs10584-016-1772-4&partnerID=40&md5=98b02a6959a9aa3f3762b31ddc9dde51","The progressive loss of Arctic sea ice leads to increased surface emissions of Dimethyl Sulphide (DMS), which is the dominant local source of sulphate aerosols. We test the hypothesis that cloud condensation nuclei, derived from DMS, will increase cloud-top albedo in an earth-system global climate model. The earth-system model includes fully interactive ocean biology, DMS, atmospheric chemistry, aerosols and cloud microphysics. In an idealised warming scenario, the Arctic Ocean becomes ice-free in summer when atmospheric CO2 is increased by 1 % per year to four times the pre-industrial concentrations. The summer boundary layer near-surface inversion strengthens, increasing stratification with warming, whilst the autumn inversion weakens. We find that the dominant change in cloud albedo arises from the conversion of summer clouds from ice to liquid, reducing the solar flux at the surface by 27 W m−2. Only 1–2 W m−2 of the reduced solar flux is attributed to cloud condensation nuclei associated with sulphate aerosols derived from the 2–5 fold increase in DMS emissions that results from an ice-free ocean. We conclude that aerosol-cloud feedbacks originating from DMS production in the Arctic region are largely mitigated through increased wet deposition of sulphate aerosols by rainfall and as a result are not a significant component of changes in the surface radiation budget in our model. © 2016, Crown Copyright."
"36676894700;25926762100;25647575500;55745992000;36085119600;56597778200;6701895637;","How well can a convection-permitting climate model reproduce decadal statistics of precipitation, temperature and cloud characteristics?",2016,"10.1007/s00382-016-3012-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957674956&doi=10.1007%2fs00382-016-3012-z&partnerID=40&md5=5a9b275b1328650d1c7dac50e218dc39","Convection-permitting climate model are promising tools for improved representation of extremes, but the number of regions for which these models have been evaluated are still rather limited to make robust conclusions. In addition, an integrated interpretation of near-surface characteristics (typically temperature and precipitation) together with cloud properties is limited. The objective of this paper is to comprehensively evaluate the performance of a ‘state-of-the-art’ regional convection-permitting climate model for a mid-latitude coastal region with little orographic forcing. For this purpose, an 11-year integration with the COSMO-CLM model at Convection-Permitting Scale (CPS) using a grid spacing of 2.8 km was compared with in-situ and satellite-based observations of precipitation, temperature, cloud properties and radiation (both at the surface and the top of the atmosphere). CPS clearly improves the representation of precipitation, in especially the diurnal cycle, intensity and spatial distribution of hourly precipitation. Improvements in the representation of temperature are less obvious. In fact the CPS integration overestimates both low and high temperature extremes. The underlying cause for the overestimation of high temperature extremes was attributed to deficiencies in the cloud properties: The modelled cloud fraction is only 46 % whereas a cloud fraction of 65 % was observed. Surprisingly, the effect of this deficiency was less pronounced at the radiation balance at the top of the atmosphere due to a compensating error, in particular an overestimation of the reflectivity of clouds when they are present. Overall, a better representation of convective precipitation and a very good representation of the daily cycle in different cloud types were demonstrated. However, to overcome remaining deficiencies, additional efforts are necessary to improve cloud characteristics in CPS. This will be a challenging task due to compensating deficiencies that currently exist in ‘state-of-the-art’ models, yielding a good representation of average climate conditions. In the light of using the CPS models to study climate change it is necessary that these deficiencies are addressed in future research. © 2016, The Author(s)."
"55880847200;15726481600;","On ISSM and leveraging the Cloud towards faster quantification of the uncertainty in ice-sheet mass balance projections",2016,"10.1016/j.cageo.2016.08.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984799833&doi=10.1016%2fj.cageo.2016.08.007&partnerID=40&md5=20d2bd846047c84b1dbca9daf17de317","With the Amazon EC2 Cloud becoming available as a viable platform for parallel computing, Earth System Models are increasingly interested in leveraging its capabilities towards improving climate projections. In particular, faced with long wait periods on high-end clusters, the elasticity of the Cloud presents a unique opportunity of potentially “infinite” availability of small-sized clusters running on high-performance instances. Among specific applications of this new paradigm, we show here how uncertainty quantification in climate projections of polar ice sheets (Antarctica and Greenland) can be significantly accelerated using the Cloud. Indeed, small-sized clusters are very efficient at delivering sensitivity and sampling analysis, core tools of uncertainty quantification. We demonstrate how this approach was used to carry out an extensive analysis of ice-flow projections on one of the largest basins in Greenland, the North-East Greenland Glacier, using the Ice Sheet System Model, the public-domain NASA-funded ice-flow modeling software. We show how errors in the projections were accurately quantified using Monte-Carlo sampling analysis on the EC2 Cloud, and how a judicious mix of high-end parallel computing and Cloud use can best leverage existing infrastructures, and significantly accelerate delivery of potentially ground-breaking climate projections, and in particular, enable uncertainty quantification that were previously impossible to achieve. © 2016 Elsevier Ltd"
"55149793500;35509639400;12801073500;7004714030;","Interpreting the inter-model spread in regional precipitation projections in the tropics: role of surface evaporation and cloud radiative effects",2016,"10.1007/s00382-016-2998-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957597050&doi=10.1007%2fs00382-016-2998-6&partnerID=40&md5=c0e7658f8965ed864c361b07b9acc5d2","In this study, we investigate and quantify different contributors to inter-model differences in regional precipitation projections among CMIP5 climate models. Contributors to the spread are very contrasted between land and ocean. While circulation changes dominate the spread over oceans and continental coasts, thermodynamic changes associated with water vapor increase dominate over inland regions. The inter-model spread in the dynamic component is associated with the change in atmospheric radiative cooling with warming, which largely relates to atmospheric cloud radiative effects. Differences in the thermodynamic component result from the differences in the change in surface evaporation that is explained by decreases in surface humidity and limited surface water availability over land. Secondary contributions to the inter-model spread in thermodynamic and dynamic components result respectively from present-day climatology (owing to the Clausius–Clapeyron scaling) and from the shape of the vertical velocity profile associated with changes in surface temperature gradients. Advancing the physical understanding of the cloud-circulation and precipitation-evaporation couplings and improving their representation in climate models may stand the best chance to reduce uncertainty in regional precipitation projections. © 2016, Springer-Verlag Berlin Heidelberg."
"6505871559;","Climate changes in atmospheric radiation parameters from the MSU meteorological observatory data",2016,"10.3103/S1068373916110078","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011387419&doi=10.3103%2fS1068373916110078&partnerID=40&md5=f62454f924266452c05624b4c33f44f5","Variations in radiation fluxes and the factors that define them and their redistribution in the atmosphere are analyzed using the data of long-term ground-based measurements at the Meteorological Observatory of Lomonosov Moscow State University. It is demonstrated that since the middle of the 1990s trends in many atmospheric radiation parameters have changed as compared to the trends observed in the previous years. For some parameters the trends are significant, are kept for a long period of time, and. hence, can be considered as climate changes. The potential effects of these changes on the regional warming are assessed. © 2016, Allerton Press, Inc."
"56959874000;26027537400;23479679000;7403918616;","Prediction of diffuse solar irradiance using machine learning and multivariable regression",2016,"10.1016/j.apenergy.2016.08.093","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983490932&doi=10.1016%2fj.apenergy.2016.08.093&partnerID=40&md5=974f9a58386065a9fd44159c532f8bad","The paper studies the horizontal global, direct-beam and sky-diffuse solar irradiance data measured in Hong Kong from 2008 to 2013. A machine learning algorithm was employed to predict the horizontal sky-diffuse irradiance and conduct sensitivity analysis for the meteorological variables. Apart from the clearness index (horizontal global/extra atmospheric solar irradiance), we found that predictors including solar altitude, air temperature, cloud cover and visibility are also important in predicting the diffuse component. The mean absolute error (MAE) of the logistic regression using the aforementioned predictors was less than 21.5 W/m2 and 30 W/m2 for Hong Kong and Denver, USA, respectively. With the systematic recording of the five variables for more than 35 years, the proposed model would be appropriate to estimate of long-term diffuse solar radiation, study climate change and develope typical meteorological year in Hong Kong and places with similar climates. © 2016 Elsevier Ltd"
"26632128800;57192958504;","Role of atmospheric carbon dioxide in climate change",2016,"10.1177/0958305X16674637","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009454678&doi=10.1177%2f0958305X16674637&partnerID=40&md5=f0f6465f5d0d95f9fc918e421dc500b5","The authors evaluate the United Nations Intergovernmental Panel on Climate Change (IPCC) consensus that the increase of carbon dioxide in the Earth’s atmosphere is of anthropogenic origin and is causing dangerous global warming, climate change and climate disruption. The totality of the data available on which that theory is based is evaluated. The data include: (a) Vostok ice-core measurements; (b) accumulation of CO2 in the atmosphere; (c) studies of temperature changes that precede CO2 changes; (d) global temperature trends; (e) current ratio of carbon isotopes in the atmosphere; (f) satellite data for the geographic distribution of atmospheric CO2; (g) effect of solar activity on cosmic rays and cloud cover. Nothing in the data supports the supposition that atmospheric CO2 is a driver of weather or climate, or that human emissions control atmospheric CO2. © 2016, © The Author(s) 2016."
"56535986400;35577912900;","An analysis of Landsat 7 and Landsat 8 underflight data and the implications for time series investigations",2016,"10.1016/j.rse.2016.02.052","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961221238&doi=10.1016%2fj.rse.2016.02.052&partnerID=40&md5=dedcb5c505368989df360deec57b39c2","The newly launched Landsat 8 satellite continues the long and extremely important record of Earth observation from the Landsat program. We analyzed differences between Landsat 7 and Landsat 8 surface reflectances and cirrus cloud characterization to address how substitutable Landsat 8 observations are within this long archive. Comparison of surface reflectance estimates acquired near simultaneously during Landsat 8's underflight orbital placement shows that Landsat 8 surface reflectance is consistently darker in the blue, green, and red bands and brighter in the near infrared than in Landsat 7. Vegetation indices that rely on the visible and near infrared bands should be used with caution as individual biases in index components can be amplified to create large biases in vegetation indices. We also analyzed time series datasets from the Landsat Climate Data Record (CDR) surface reflectance product across four scenes that contained only Landsat 7 data, Landsat 7 data and only Landsat 8 data post-launch, and Landsat 7 data and data from both sensors post-launch to investigate how sensor differences propagate in time series analysis. If left uncorrected or unexplained, the difference in reflectance between Landsat 7 and Landsat 8 creates spurious time trends in visible wavelengths and in the Normalized Difference Vegetation Index (NDVI). The introduction of Landsat 8 into time series of Landsat 7 data also biases the mean reflectance or vegetation index value as measured by a time series model intercept while increasing the Root Mean Squared Error of such models. We characterized the spectral reflectance of cirrus clouds in the underflight data that were omitted from Landsat 7 cloud masks but were detected in Landsat 8's cloud mask due to the use of the newly added cirrus band. While these cirrus cloud observations missed in Landsat 7's cloud mask are only slightly brighter in the visible bands, a simulation of time series containing Landsat 8 data that does not use the cirrus band shows that omission of cirrus clouds can result in anomalously brighter time series intercepts and positive time trends. Our results indicate that while Landsat 8 has improved on the legacy of previous sensors through increased radiometric resolution, better cloud identification, and better geometric accuracy, difference in reflectance between sensors in the current Landsat CDR product must be corrected or explained within time series analysis to avoid deleterious consequences. Future efforts should identify the contributions of target specific effects versus differences in atmospheric correction methods to better inform approaches to synthesize the two sensors. © 2016 Elsevier Inc."
"56544915700;7102591209;56218570500;26659013400;9043417100;7402883211;","Using laboratory and field measurements to constrain a single habit shortwave optical parameterization for cirrus",2016,"10.1016/j.atmosres.2016.05.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973137844&doi=10.1016%2fj.atmosres.2016.05.005&partnerID=40&md5=7814bce28e54f118e767e0c30b338aa6","A single habit parameterization for the shortwave optical properties of cirrus is presented. The parameterization utilizes a hollow particle geometry, with stepped internal cavities as identified in laboratory and field studies. This particular habit was chosen as both experimental and theoretical results show that the particle exhibits lower asymmetry parameters when compared to solid crystals of the same aspect ratio. The aspect ratio of the particle was varied as a function of maximum dimension, D, in order to adhere to the same physical relationships assumed in the microphysical scheme in a configuration of the Met Office atmosphere-only global model, concerning particle mass, size and effective density. Single scattering properties were then computed using T-Matrix, Ray Tracing with Diffraction on Facets (RTDF) and Ray Tracing (RT) for small, medium, and large size parameters respectively. The scattering properties were integrated over 28 particle size distributions as used in the microphysical scheme. The fits were then parameterized as simple functions of Ice Water Content (IWC) for 6 shortwave bands. The parameterization was implemented into the GA6 configuration of the Met Office Unified Model along with the current operational long-wave parameterization. The GA6 configuration is used to simulate the annual twenty-year short-wave (SW) fluxes at top-of-atmosphere (TOA) and also the temperature and humidity structure of the atmosphere. The parameterization presented here is compared against the current operational model and a more recent habit mixture model. © 2016 The Authors."
"56581521400;6602835302;47861167400;","Bias correction method for solar radiation based on quantile mapping to provide weather data for building energy simulations",2016,"10.3130/aije.81.1047","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84999098787&doi=10.3130%2faije.81.1047&partnerID=40&md5=41372c41452b0a9a407ea9330eb3b3ae","The weather and climate model output has systematical errors called the bias. Bias corrections are necessary in order to use the model output for an application field, such as in building energy simulation (BES). In general, climate models can predict the daily maximum amount of solar radiation on clear days with sufficient accuracy. However, it is difficult to accurately model cloud physics processes, with model results sometimes predicting less cloudy days compared with the actual observations. When we correct solar radiation bias using a conventional bias correction method (BCM), which uses only the average solar radiation, the daily maximum value deviates significantly from the observed results, even when the daily average is accurate. In this paper, we present a BCM called quantile mapping (QM), which considers both the daily integrated and the maximum amount of solar radiation to provide the bias corrected weather data for the BES. In addition, we conducted BESs using the corrected weather data to evaluate the efficiency of the QM. When using the weather data corrected only by the monthly average, the BES could predict the average energy consumption, but the maximum cooling load was underestimated by 12%. Conversely, when using the data corrected by QM using either the daily cumulative or the maximum amount of solar radiation, the BES predicted the maximum cooling load with only 6% and 2% respectively."
"7006544303;6602074445;55694342800;57203056781;57190373294;7005246733;8576918600;8699799400;57190380494;35551859000;","Assessing the role of climate and resource management on groundwater dependent ecosystem changes in arid environments with the Landsat archive",2016,"10.1016/j.rse.2016.07.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979620817&doi=10.1016%2fj.rse.2016.07.004&partnerID=40&md5=53e4151855f9bac157506f107ec49aee","Groundwater dependent ecosystems (GDEs) rely on near-surface groundwater. These systems are receiving more attention with rising air temperature, prolonged drought, and where groundwater pumping captures natural groundwater discharge for anthropogenic use. Phreatophyte shrublands, meadows, and riparian areas are GDEs that provide critical habitat for many sensitive species, especially in arid and semi-arid environments. While GDEs are vital for ecosystem services and function, their long-term (i.e. ~ 30 years) spatial and temporal variability is poorly understood with respect to local and regional scale climate, groundwater, and rangeland management. In this work, we compute time series of NDVI derived from sensors of the Landsat TM, ETM +, and OLI lineage for assessing GDEs in a variety of land and water management contexts. Changes in vegetation vigor based on climate, groundwater availability, and land management in arid landscapes are detectable with Landsat. However, the effective quantification of these ecosystem changes can be undermined if changes in spectral bandwidths between different Landsat sensors introduce biases in derived vegetation indices, and if climate, and land and water management histories are not well understood. The objective of this work is to 1) use the Landsat 8 under-fly dataset to quantify differences in spectral reflectance and NDVI between Landsat 7 ETM + and Landsat 8 OLI for a range of vegetation communities in arid and semiarid regions of the southwestern United States, and 2) demonstrate the value of 30-year historical vegetation index and climate datasets for assessing GDEs. Specific study areas were chosen to represent a range of GDEs and environmental conditions important for three scenarios: baseline monitoring of vegetation and climate, riparian restoration, and groundwater level changes. Google's Earth Engine cloud computing and environmental monitoring platform is used to rapidly access and analyze the Landsat archive along with downscaled North American Land Data Assimilation System gridded meteorological data, which are used for both atmospheric correction and correlation analysis. Results from the cross-sensor comparison indicate a benefit from the application of a consistent atmospheric correction method, and that NDVI derived from Landsat 7 and 8 are very similar within the study area. Results from continuous Landsat time series analysis clearly illustrate that there are strong correlations between changes in vegetation vigor, precipitation, evaporative demand, depth to groundwater, and riparian restoration. Trends in summer NDVI associated with riparian restoration and groundwater level changes were found to be statistically significant, and interannual summer NDVI was found to be moderately correlated to interannual water-year precipitation for baseline study sites. Results clearly highlight the complementary relationship between water-year PPT, NDVI, and evaporative demand, and are consistent with regional vegetation index and complementary relationship studies. This work is supporting land and water managers for evaluation of GDEs with respect to climate, groundwater, and resource management. © 2016 The Authors"
"56542536900;57214672257;56130488100;","Aerosol climatology over the Bay of Bengal and Arabian Sea inferred from space-borne radiometers and lidar observations",2016,"10.4209/aaqr.2015.06.0406","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994165155&doi=10.4209%2faaqr.2015.06.0406&partnerID=40&md5=815d64e5b579c04ec789761069913fc0","Atmospheric aerosols over the oceanic region are very important air pollutant and play a vital role in Earth’s radiation budget and climate change. This study presents the aerosol climatology over the Bay of Bengal (BoB) and Arabian sea (AS) using long term (2006–2012) data from space-borne radiometers [Moderate-Resolution Imaging Spectroradiometer (MODIS), Ozone Monitoring Instrument (OMI)] and space-based active lidar onboard Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). AS experiences higher AOD as compared to that over BoB during the study period. A good periodicity along with strong intra-seasonal/annual variability in aerosol loading is also observed over both the study regions. Approximately one month lag is found for maximum aerosol loading period over AS and BoB for almost every year i.e., June–July for AS and May–June for BoB. This lag could be explained by pathway and timing of summer monsoon over the Indian subcontinent. Elevated layers of absorbing dust up to 2–4 km altitudes are observed during the pre-monsoon and monsoon seasons over both the regions. The CALIPSO measurements show strong seasonal heterogeneity in aerosol properties over both the regions, which is well corroborated with MODIS and OMI observations. This significant seasonal heterogeneity in aerosol loading has been explained by the role of transportation of aerosols from various emission sources using NOAA HYSPLIT back trajectory model at three different altitude levels viz. 500, 1500 and 2500 m height. The possible role of Indian summer monsoon in modulating the aerosol behaviour over AS and BoB is another important aspect of this study that need further analyses using higher spatio-temporal resolution data. © Taiwan Association for Aerosol Research."
"8684665500;57190175163;55581431800;8684665200;6603930958;56668741500;6602442573;16304037700;36176023600;23489874800;6602108536;15135310700;7003696043;12796720800;57203490976;7003707334;6507441106;7201749564;6603547223;55773759200;6508345775;6602917435;14423924200;55899638400;57190953051;55929408400;14424147300;57190956490;57216641435;14007295200;55030102900;14622943900;16307479200;6602608183;57213411204;7004386091;57195933215;24076742800;19035625400;56397031600;16481128500;57190425858;56086811300;57190953313;26436137300;7004813375;36154020700;16305437300;7004601047;7006742178;7005394885;","The rich sides of mountain summits – a pan-European view on aspect preferences of alpine plants",2016,"10.1111/jbi.12835","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984697671&doi=10.1111%2fjbi.12835&partnerID=40&md5=81cc2af98ee37b14c4e30ff4ae9c805f","Aim: In the alpine life zone, plant diversity is strongly determined by local topography and microclimate. We assessed the extent to which aspect and its relatedness to temperature affect plant species diversity, and the colonization and disappearance of species on alpine summits on a pan-European scale. Location: Mountain summits in Europe's alpine life zone. Methods: Vascular plant species and their percentage cover were recorded in permanent plots in each cardinal direction on 123 summits in 32 regions across Europe. For a subset from 17 regions, resurvey data and 6-year soil temperature series were available. Differences in temperature sum and Shannon index as well as species richness, colonization and disappearance of species among cardinal directions were analysed using linear mixed-effects and generalised mixed-effects models, respectively. Results: Temperature sums were higher in east- and south-facing aspects than in the north-facing ones, while the west-facing ones were intermediate; differences were smallest in northern Europe. The patterns of temperature sums among aspects were consistent among years. In temperate regions, thermal differences were reflected by plant diversity, whereas this relationship was weaker or absent on Mediterranean and boreal mountains. Colonization of species was positively related to temperature on Mediterranean and temperate mountains, whereas disappearance of species was not related to temperature. Main conclusions: Thermal differences caused by solar radiation determine plant species diversity on temperate mountains. Advantages for plants on eastern slopes may result from the combined effects of a longer diurnal period of radiation due to convection cloud effects in the afternoon and the sheltered position against the prevailing westerly winds. In northern Europe, long summer days and low sun angles can even out differences among aspects. On Mediterranean summits, summer drought may limit species numbers on the warmer slopes. Warmer aspects support a higher number of colonization events. Hence, aspect can be a principal determinant of the pace of climate-induced migration processes. © 2016 John Wiley & Sons Ltd"
"55053404100;7101899854;24344262300;23012437100;57191848056;34969663100;18635289400;16551540700;7202485447;57191845088;6602406924;24172779500;55330758500;","COMMIT in 7-SEAS/BASELINE: Operation of and observations from a novel, mobile laboratory for measuring in-situ properties of aerosols and gases",2016,"10.4209/aaqr.2015.11.0630","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994108624&doi=10.4209%2faaqr.2015.11.0630&partnerID=40&md5=f200fdb7c5046cc9117b69395b9dec7c","Trace gases and aerosols (particularly biomass-burning aerosols) have important implications for air quality and climate studies in Southeast Asia (SEA). This paper describes the purpose, operation, and datasets collected from NASA Goddard Space Flight Center’s (NASA/GSFC) Chemical, Optical, and Microphysical Measurements of In-situ Troposphere (COMMIT) laboratory, a mobile platform designed to measure trace gases and optical/microphysical properties of naturally occurring and anthropogenic aerosols. More importantly, the laboratory houses a specialized humidification system to characterize hygroscopic growth/enhancement, a behavior that affects aerosol properties and cloud-aerosol interactions and is generally underrepresented in the current literature. A summary of the trace gas and optical/microphysical measurements is provided, along with additional detail and analysis of data collected from the hygroscopic system during the 2015 Seven South-East Asian Studies (7-SEAS) field campaign. The results suggest that data from the platform are reliable and will complement future studies of aerosols and air quality in SEA and other regions of interest. © Taiwan Association for Aerosol Research."
"57191263798;53986492000;57196087358;","Chemical characteristics of aerosol and rain water during an El Niño and PDO influenced Indian summer monsoon",2016,"10.1016/j.atmosenv.2016.09.026","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988521738&doi=10.1016%2fj.atmosenv.2016.09.026&partnerID=40&md5=898b3626503b5e7cbed7937a86628616","According to the meteorological long-term variability pattern, year 2015 was influenced by El Niño and PDO (Pacific Decadal Oscillation; causes weakening of Indian Summer Monsoon). These conditions facilitate the assessment of chemical characteristics of fine-mode ambient aerosols (PM2.5; n = 48) and individual rain waters (pH: 6.4–7.6; n = 15) during the South-west monsoon (July–September 2015) in the central Indo-Gangetic Plain (IGP; Kanpur). Water-soluble ionic species (WSIS) have been measured to assess the undergoing processes (neutralization, formation and below-cloud scavenging) and estimate their dry and wet deposition fluxes. The ∑WSIS varies from 4 to 32 μg/m3 in PM2.5, whereas it ranges from 32 to 102 mg/L in rain waters. The NH4+ and SO42− are found to be predominant in PM2.5 (16–120 μg/m3), whereas HCO3− and Ca2+ are predominant in rain water samples. The difference in chemical composition of PM2.5 and rain water is largely attributed to additional contribution of coarse-mode mineral dust in rain water. The Ca2+ and Mg2+ in both aerosols and rain water samples are associated with HCO3−. The NO3− and SO42− are neutralized predominantly by NH4+ and ∑−/∑+ ratio is ≈ 1 in both aerosols and rain waters. Furthermore, co-variability of NO3− with nss-Ca2+ in PM2.5 indicates role of fine-mode mineral dust surface in the formation of ammonium nitrate. Characteristic mass ratios (HCO3−/Ca2+ and SO42−/NH4+) in rain water look quite similar to those in aerosols (PM2.5). This suggests that below-cloud scavenging is predominant mechanism of aerosols wash-out. Dry deposition fluxes of Mg2+, NH4+ and SO42− are ∼13% of their wet deposition fluxes, whereas for K+, Ca2+ and NO3− it is &lt;6%. © 2016 Elsevier Ltd"
"22956851400;7402170368;56681990300;8881933900;26028957000;8662096300;23032969000;35476924900;","Mapping paddy rice planting area in northeastern Asia with Landsat 8 images, phenology-based algorithm and Google Earth Engine",2016,"10.1016/j.rse.2016.02.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961219003&doi=10.1016%2fj.rse.2016.02.016&partnerID=40&md5=85dfa50c0f231640ab830641303426c4","Area and spatial distribution information of paddy rice are important for understanding of food security, water use, greenhouse gas emission, and disease transmission. Due to climatic warming and increasing food demand, paddy rice has been expanding rapidly in high latitude areas in the last decade, particularly in northeastern (NE) Asia. Current knowledge about paddy rice fields in these cold regions is limited. The phenology- and pixel-based paddy rice mapping (PPPM) algorithm, which identifies the flooding signals in the rice transplanting phase, has been effectively applied in tropical areas, but has not been tested at large scale of cold regions yet. Despite the effects from more snow/ice, paddy rice mapping in high latitude areas is assumed to be more encouraging due to less clouds, lower cropping intensity, and more observations from Landsat sidelaps. Moreover, the enhanced temporal and geographic coverage from Landsat 8 provides an opportunity to acquire phenology information and map paddy rice. This study evaluated the potential of Landsat 8 images on annual paddy rice mapping in NE Asia which was dominated by single cropping system, including Japan, North Korea, South Korea, and NE China. The cloud computing approach was used to process all the available Landsat 8 imagery in 2014 (143 path/rows, ~ 3290 scenes) with the Google Earth Engine (GEE) platform. The results indicated that the Landsat 8, GEE, and improved PPPM algorithm can effectively support the yearly mapping of paddy rice in NE Asia. The resultant paddy rice map has a high accuracy with the producer (user) accuracy of 73% (92%), based on the validation using very high resolution images and intensive field photos. Geographic characteristics of paddy rice distribution were analyzed from aspects of country, elevation, latitude, and climate. The resultant 30-m paddy rice map is expected to provide unprecedented details about the area, spatial distribution, and landscape pattern of paddy rice fields in NE Asia, which will contribute to food security assessment, water resource management, estimation of greenhouse gas emissions, and disease control. © 2016 Elsevier Inc."
"57016828200;55362307100;","Frequency scaling of slant-path atmospheric attenuation in the absence of rain for millimeter-wave links",2016,"10.1002/2016RS006103","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996572980&doi=10.1002%2f2016RS006103&partnerID=40&md5=bd280daad97857ca3858003aef8c05a6","Broadband satellite communications systems, either used for broadcast or fixed satellite services, have grown continuously in recent years. This has led to the use of higher frequency bands, from the Ku (14/11 GHz) to the Ka band (30/20 GHz) in the last decade, and with the expectation of using the Q/V band (50/40 GHz) and even the W band (75–110 GHz) in the future. As frequency increases, radio wave propagation effects in the slant-path within the troposphere are becoming more and more relevant. The objective of this research is the proposal of frequency scaling approximations for the total attenuation in the absence of rain, a condition that occurs during the highest percentages of time, usually more than 95% in temperate climates. There is a strong relationship between total attenuation at different frequencies, as it arises from the same physical phenomena, namely, the presence of oxygen, water vapor, and clouds in the slant path. This strong relationship allows frequency scaling estimations to be proposed. In particular, polynomials for instantaneous frequency scaling of total attenuation under these conditions have been calculated for a set of frequencies in the range 10–100 GHz, based on atmospheric profiles of 60 sites from all over the world and physical models of attenuation. Global polynomials are provided for the 72 combinations of nine significant frequencies, which can be used to estimate attenuation at a frequency band from its known value at a different one. Refined expressions have also been calculated for different climatic zones, providing more precise estimations. ©2016. American Geophysical Union. All Rights Reserved."
"55745404300;57203052274;55857012500;35368622800;56872235400;55566467600;6603779272;6601992794;55850540800;8667844900;35182454400;35448188800;57209178256;7003729315;7102336894;7005891596;6701859178;7402185841;55619886800;6701691393;55925502100;7102634471;","Observing atmospheric formaldehyde (HCHO) from space: Validation and intercomparison of six retrievals from four satellites (OMI, GOME2A, GOME2B, OMPS) with SEAC4RS aircraft observations over the southeast US",2016,"10.5194/acp-16-13477-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994323910&doi=10.5194%2facp-16-13477-2016&partnerID=40&md5=496175d2729e040ce5e1259ccfe0f6d0","Formaldehyde (HCHO) column data from satellites are widely used as a proxy for emissions of volatile organic compounds (VOCs), but validation of the data has been extremely limited. Here we use highly accurate HCHO aircraft observations from the NASA SEAC4RS (Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) campaign over the southeast US in August-September 2013 to validate and intercompare six retrievals of HCHO columns from four different satellite instruments (OMI, GOME2A, GOME2B and OMPS; for clarification of these and other abbreviations used in the paper, please refer to Appendix A) and three different research groups. The GEOS-Chem chemical transport model is used as a common intercomparison platform. All retrievals feature a HCHO maximum over Arkansas and Louisiana, consistent with the aircraft observations and reflecting high emissions of biogenic isoprene. The retrievals are also interconsistent in their spatial variability over the southeast US (r Combining double low line 0.4-0.8 on a 0.5° × 0.5° grid) and in their day-to-day variability (r Combining double low line 0.5-0.8). However, all retrievals are biased low in the mean by 20-51 %, which would lead to corresponding bias in estimates of isoprene emissions from the satellite data. The smallest bias is for OMI-BIRA, which has high corrected slant columns relative to the other retrievals and low scattering weights in its air mass factor (AMF) calculation. OMI-BIRA has systematic error in its assumed vertical HCHO shape profiles for the AMF calculation, and correcting this would eliminate its bias relative to the SEAC4RS data. Our results support the use of satellite HCHO data as a quantitative proxy for isoprene emission after correction of the low mean bias. There is no evident pattern in the bias, suggesting that a uniform correction factor may be applied to the data until better understanding is achieved. © Author(s) 2016."
"13402835300;24329376600;24597575200;7003976079;","Cloud liquid water path and radiative feedbacks over the Southern Ocean",2016,"10.1002/2016GL070770","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995701641&doi=10.1002%2f2016GL070770&partnerID=40&md5=4c608db4ad4fb93c5f2c3207937df4b4","Climate models show a robust shortwave negative feedback in the midlatitude oceans in climate change simulations. This feedback is commonly attributed to an increase in cloud optical depth due to ice to liquid phase change as the climate warms. Here we use a cyclone compositing technique to show that the models' cloud liquid water path (LWP) response is strongly dependent on cloud regime. The radiative and LWP responses are not as tightly coupled as a zonal-mean analysis would suggest, implying that the physical mechanisms that control the overall LWP response are not necessarily responsible for the radiative response. The area of the cyclone dominated by low-level stratiform and shallow convective clouds plays a dominant role in the radiative response. Since these are mostly supercooled liquid clouds, the strength of a negative cloud phase feedback in the real world should be smaller than the one predicted by current models. ©2016 Crown copyright. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland."
"57188745140;57196143493;55675283100;6506385754;55926866400;24554163500;57206166579;55656837900;","An assessment of the radiative effects of ice supersaturation based on in situ observations",2016,"10.1002/2016GL071144","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995578211&doi=10.1002%2f2016GL071144&partnerID=40&md5=8191a4485f6d0ad84b828f287fb86a2a","We use aircraft observations combined with the reanalysis data to investigate the radiative effects of ice supersaturation (ISS). Our results show that although the excess water vapor over ice saturation itself has relatively small radiative effects, mistaking it as ice crystals in climate models would lead to considerable impacts: on average, +2.49 W/m2 change in the top of the atmosphere (TOA) radiation, −2.7 W/m2 change in surface radiation, and 1.47 K/d change in heating rates. The radiative effects of ISS generally increase with the magnitudes of supersaturation. However, there is a strong dependence on the preexisting ice water path, which can even change the sign of the TOA radiative effect. It is therefore important to consider coexistence between ISS and ice clouds and to validate their relationship in the parameterizations of ISS in climate models. ©2016. American Geophysical Union. All Rights Reserved."
"56892889800;7501757094;","An effective approach to evaluate GCM simulated diurnal variation of clouds",2016,"10.1002/2016GL070446","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995378465&doi=10.1002%2f2016GL070446&partnerID=40&md5=fd0a7ed523e708fddafcf6b77deebc04","Cloud radiative effects strongly depend on diurnal variations of insolation and cloud radiative properties. In general circulation models (GCMs), even when the daily-mean cloud properties agree with observations, errors in cloud diurnal cycle can still significantly impact the shortwave radiation and induce model biases. However, this aspect is overlooked in GCM evaluation and intercomparison programs (e.g., Coupled Model Intercomparison Project Phase 5 (CMIP5)), which mainly consider the daily-mean cloud fraction. This study presents a simple approach of using a diagnostic parameter, the “effective-daytime cloud fraction” which accounts for the concurrent variation of clouds and insolation, to reveal GCM biases in cloud diurnal variations. The usefulness of the approach is illustrated by the significant biases of cloud diurnal cycle in the Modern-Era Retrospective analysis for Research and Applications (MERRA) reanalysis when compared with that in the International Satellite Cloud Climatology Project (ISCCP) data. It is thus suggested that the parameter be included as one of the GCM diagnostics for evaluating cloud diurnal cycle in model intercomparisons. ©2016. American Geophysical Union. All Rights Reserved."
"56193650100;55871347000;","The effect of subtropical aerosol loading on equatorial precipitation",2016,"10.1002/2016GL071206","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995653325&doi=10.1002%2f2016GL071206&partnerID=40&md5=c7c3904a13fe49fdc7529116e2e5a3f5","Cloud-aerosol interactions are considered as one of the largest sources of uncertainties in the study of climate change. Here another possible cloud-aerosol effect on climate is proposed. A series of large eddy simulations (LES) with bin microphysics reveal a sensitivity of the total atmospheric water vapor amount to aerosol concentration. Under polluted conditions the rain is suppressed and the total amount of water vapor in the atmosphere increases with time compared to clean precipitating conditions. Theoretical examination of this aerosol effect on water vapor transport from the subtropics to the tropics, and hence on the equatorial rain and Hadley circulation, is conducted using an idealized general circulation model (GCM). It is shown that a reduction in the subtropical rain amount results in increased water vapor advection to the tropics and enhanced equatorial rain and Hadley circulation. This joins previously proposed mechanisms on the radiative aerosol effect on the general circulation. ©2016. American Geophysical Union. All Rights Reserved."
"7004544454;22635123500;24467873200;15829918100;6506122183;57190738341;55894937000;6506738307;6507501796;","Can reducing the incoming energy flux over the Southern Ocean in a CGCM improve its simulation of tropical climate?",2016,"10.1002/2016GL071150","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995555427&doi=10.1002%2f2016GL071150&partnerID=40&md5=7aeb8deaca46c677fd727eca599749c3","Atmosphere-ocean general circulation models (CGCMs) show important systematic errors. Simulated precipitation in the tropics is generally overestimated over the oceans south of the equator, and stratocumulus (SCu) clouds are underestimated above too warm sea surface temperatures (SSTs). In the extratropics, SSTs are also too warm over the Southern Ocean. We argue that ameliorating these extratropical errors in a CGCM can result in an improved model's performance in the tropics depending upon the success in simulating the sensitivity of SCu to underlying SST. Our arguments are supported by the very different response obtained with two CGCMs to an idealized reduction of solar radiation flux incident at the top of the atmosphere over the Southern Ocean. It is shown that local perturbation impacts are very similar in the two models but that SST reductions in the SCu regions of the southern subtropics are stronger in the model with the stronger SCu-SST feedbacks. ©2016. American Geophysical Union. All Rights Reserved."
"8953662800;55153585300;57213521610;56610914500;7409080503;55813627900;57189621839;57189328603;57191828766;7004333708;55543826100;","The climatology of planetary boundary layer height in China derived from radiosonde and reanalysis data",2016,"10.5194/acp-16-13309-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84993660384&doi=10.5194%2facp-16-13309-2016&partnerID=40&md5=0f7224a0b5e8498dc82bcc4527532504","The important roles of the planetary boundary layer (PBL) in climate, weather and air quality have long been recognized, but little is known about the PBL climatology in China. Using the fine-resolution sounding observations made across China and reanalysis data, we conducted a comprehensive investigation of the PBL in China from January 2011 to July 2015. The boundary layer height (BLH) is found to be generally higher in spring and summer than that in fall and winter. The comparison of seasonally averaged BLHs derived from observations and reanalysis, on average, shows good agreement, despite the pronounced inconsistence in some regions. The BLH, derived from soundings conducted three or four times daily in summer, tends to peak in the early afternoon, and the diurnal amplitude of BLH is higher in the northern and western subregions of China than other subregions. The meteorological influence on the annual cycle of BLH is investigated as well, showing that BLH at most sounding sites is negatively associated with the surface pressure and lower tropospheric stability, but positively associated with the near-surface wind speed and temperature. In addition, cloud tends to suppress the development of PBL, particularly in the early afternoon. This indicates that meteorology plays a significant role in the PBL processes. Overall, the key findings obtained from this study lay a solid foundation for us to gain a deep insight into the fundamentals of PBL in China, which helps to understand the roles that the PBL plays in the air pollution, weather and climate of China. © Author(s) 2016."
"36866503400;36138641800;","On the limited ice intrusion in Alaska at the LGM",2016,"10.1002/2016GL071012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995653358&doi=10.1002%2f2016GL071012&partnerID=40&md5=a9191e735eed9927ccc682bcd8867772","The Last Glacial Maximum (LGM) Laurentide Ice Sheet covered most of the North American continent poleward of 40°N, with the exception of Alaska that remained relatively warm, dry, and largely ice free. Experiments with a global atmospheric circulation model are in broad agreement with proxies: the Alaskan summer temperatures are comparable to the preindustrial, and the annual precipitation is reduced by 30–50%. The warm conditions are attributed to a lowering of the local planetary albedo—due to a decreased cloudiness in response to the cold LGM sea surface temperatures (SSTs) and a stationary anticyclone forced by the ice sheet—that allows more shortwave radiation to reach the surface. Stationary waves are shown to counteract the shortwave cloud feedback by converging less heat over the target region. The LGM SST field also yields an equatorward shifted Pacific stormtrack, which results in drier conditions in Alaska and abundant precipitation at the southern margin of the Laurentide Ice Sheet. ©2016. American Geophysical Union. All Rights Reserved."
"57095869500;7404297096;","The open-ocean sensible heat flux and its significance for Arctic boundary layer mixing during early fall",2016,"10.5194/acp-16-13173-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84993929128&doi=10.5194%2facp-16-13173-2016&partnerID=40&md5=1735f0b9932df3d66da723519fdf3784","The increasing ice-free area during late summer has transformed the Arctic to a climate system with more dynamic boundary layer (BL) clouds and seasonal sea ice growth. The open-ocean sensible heat flux, a crucial mechanism of excessive ocean heat loss to the atmosphere during the fall freeze season, is speculated to play an important role in the recently observed cloud cover increase and BL instability. However, lack of observations and understanding of the resilience of the proposed mechanisms, especially in relation to meteorological and interannual variability, has left a poorly constrained BL parameterization scheme in Arctic climate models. In this study, we use multiyear Japanese cruise-ship observations from R/V Mirai over the open Arctic Ocean to characterize the surface sensible heat flux (SSHF) during early fall and investigate its contribution to BL turbulence. It is found that mixing by SSHF is favored during episodes of high surface wind speed and is also influenced by the prevailing cloud regime. The deepest BLs and maximum ocean-atmosphere temperature difference are observed during cold air advection (associated with the stratocumulus regime), yet, contrary to previous speculation, the efficiency of sensible heat exchange is low. On the other hand, the SSHF contributes significantly to BL mixing during the uplift (low pressure) followed by the highly stable (stratus) regime. Overall, it can explain ∼10% of the openocean BL height variability, whereas cloud-driven (moisture and radiative) mechanisms appear to be the other dominant source of convective turbulence. Nevertheless, there is strong interannual variability in the relationship between the SSHF and the BL height which can be intensified by the changing occurrence of Arctic climate patterns, such as positive surface wind speed anomalies and more frequent conditions of uplift. This study highlights the need for comprehensive BL observations like the R/V Mirai for better understanding and predicting the dynamic nature of the Arctic climate. © 2016 The Author(s)."
"54080103500;36653408700;55622628300;26666431500;7202954964;8618000600;","Precursors of deep moist convection in a subkilometer global simulation",2016,"10.1002/2016JD024965","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995595410&doi=10.1002%2f2016JD024965&partnerID=40&md5=2c8ac9429f81585953c86173fdf104e4","Deepmoist convection in the atmosphere plays an important role in cloudy weather disturbances, such as hurricanes, and even in the global climate. The convection often causes disastrous heavy rainfall, and predicting such convection is therefore critical for both disaster prevention and climate projection. Although the key parameters for convection have been pointed out, understanding the preprocesses of convection is a challenging issue. Here we identified the precursors of convection by analyzing a global simulated data set with very high resolution in time and space. We found that the mass convergence near the Earth’s surface changed significantly several minutes before the initiation of early convection (the formation of cumulus clouds), which occurred with the increase in the convective available potential energy (CAPE). Decomposition of the statistical data revealed that a higher-CAPE environment resulted in stronger convection than in the stronger-convergence case. Furthermore, for the stronger-convergence case, the precursor was detected earlier than the total average (10-15 min before the initiation), whereas the amplitude of maximum velocity was not so strong as the higher-CAPE case. This suggests that the strength of convection is connected with CAPE, and the predictability is sensitive to the convergence. © 2016. American Geophysical Union. All Rights Reserved."
"57207816840;55480824500;6507952920;55897485300;56549888700;36476746800;7003430284;7405588225;7004557898;7006219023;","Using satellite-based measurements to explore spatiotemporal scales and variability of drivers of new particle formation",2016,"10.1002/2016JD025568","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991607085&doi=10.1002%2f2016JD025568&partnerID=40&md5=b675d711be18e4173b927f4dd20edac1","New particle formation (NPF) can potentially alter regional climate by increasing aerosol particle (hereafter particle) number concentrations and ultimately cloud condensation nuclei. The large scales on which NPF is manifest indicate potential to use satellite-based (inherently spatially averaged) measurements of atmospheric conditions to diagnose the occurrence of NPF and NPF characteristics. We demonstrate the potential for using satellite-based measurements of insolation (UV), trace gas concentrations (sulfur dioxide (SO2), nitrogen dioxide (NO2), ammonia (NH3), formaldehyde (HCHO), and ozone (O3)), aerosol optical properties (aerosol optical depth (AOD) and Ångström exponent (AE)), and a proxy of biogenic volatile organic compound emissions (leaf area index (LAI) and temperature (T)) as predictors for NPF characteristics: formation rates, growth rates, survival probabilities, and ultrafine particle (UFP) concentrations at five locations across North America. NPF at all sites is most frequent in spring, exhibits a one-day autocorrelation, and is associated with low condensational sink(AOD × AE) andHCHOconcentrations, and high UV. However, there are important site-to-site variations in NPF frequency and characteristics, and in which of the predictor variables (particularly gas concentrations) significantly contribute to the explanatory power of regression models built to predict those characteristics. This finding may provide a partial explanation for the reported spatial variability in skill of simple generalized nucleation schemes in reproducing observed NPF. In contrast to more simple proxies developed in prior studies (e.g., based on AOD, AE, SO2, and UV), use of additional predictors (NO2, NH3, HCHO, LAI, T, and O3) increases the explained temporal variance of UFP concentrations at all sites. © 2016. American Geophysical Union. All Rights Reserved."
"55973913400;56387142000;6701842515;55999273500;57189089842;55730602600;56613109400;56442378900;7005069415;7006434689;14034301300;","Ice residual properties in mixed-phase clouds at the high-alpine jungfraujoch site",2016,"10.1002/2016JD024894","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995609108&doi=10.1002%2f2016JD024894&partnerID=40&md5=1c91cba89df00f672117e32f2153d4d8","Ice residual (IR) and total aerosol properties were measured in mixed-phase clouds (MPCs) at the high-alpine Jungfraujoch research station. Black carbon (BC) content and coating thickness of BC-containing particles were determined using single-particle soot photometers. The ice activated fraction (IAF), derived from a comparison of IR and total aerosol particle size distributions, showed an enrichment of large particles in the IR, with an increase in the IAF from values on the order of 10-4 to 10-3 for 100 nm (diameter) particles to 0.2 to 0.3 for 1 µm (diameter) particles. Nonetheless, due to the high number fraction of submicrometer particles with respect to total particle number, IR size distributions were still dominated by the submicrometer aerosol. A comparison of simultaneously measured number size distributions of BC-free and BC-containing IR and total aerosol particles showed depletion of BC by number in the IR, suggesting that BC does not play a significant role in ice nucleation in MPCs at the Jungfraujoch. The potential anthropogenic climate impact of BC via the glaciation effect in MPCs is therefore likely to be negligible at this site and in environments with similar meteorological conditions and a similar aerosol population. The IAF of the BC-containing particles also increased with total particle size, in a similar manner as for the BC-free particles, but on a level 1 order of magnitude lower. Furthermore, BC-containing IR were found to have a thicker coating than the BC-containing total aerosol, suggesting the importance of atmospheric aging for ice nucleation. © 2016. American Geophysical Union. All Rights Reserved."
"24172248700;15724233200;25630924500;35369409100;55356838400;57189368623;9846688600;7006595513;55942083800;","A broad supersaturation scanning (BS2) approach for rapid measurement of aerosol particle hygroscopicity and cloud condensation nuclei activity",2016,"10.5194/amt-9-5183-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992694448&doi=10.5194%2famt-9-5183-2016&partnerID=40&md5=25f51eca42e4c710f4fc9aee2fe343d0","The activation and hygroscopicity of cloud condensation nuclei (CCN) are key to the understanding of aerosol-cloud interactions and their impact on climate. They can be measured by scanning the particle size and supersaturation in CCN measurements. The scanning of supersaturation is often time-consuming and limits the temporal resolution and performance of CCN measurements. Here we present a new approach, termed the broad supersaturation scanning (BS2) method, in which a range of supersaturation is simultaneously scanned, reducing the time interval between different supersaturation scans. The practical applicability of the BS2 approach is demonstrated with nano-CCN measurements of laboratory-generated aerosol particles. Model simulations show that the BS2 approach may also be applicable for measuring CCN activation of ambient mixed particles. Due to its fast response and technical simplicity, the BS2 approach may be well suited for aircraft and long-term measurements. Since hygroscopicity is closely related to the fraction of organics/inorganics in aerosol particles, a BS2-CCN counter can also serve as a complementary sensor for fast detection/estimation of aerosol chemical compositions."
"7103271625;15848674200;55683037100;57189498750;7102665209;","Are atmospheric updrafts a key to unlocking climate forcing and sensitivity?",2016,"10.5194/acp-16-12983-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992699431&doi=10.5194%2facp-16-12983-2016&partnerID=40&md5=88f70eb70393af88fb67fe7ef45db552","Both climate forcing and climate sensitivity persist as stubborn uncertainties limiting the extent to which climate models can provide actionable scientific scenarios for climate change. A key, explicit control on cloud-aerosol interactions, the largest uncertainty in climate forcing, is the vertical velocity of cloud-scale updrafts. Model-based studies of climate sensitivity indicate that convective entrainment, which is closely related to updraft speeds, is an important control on climate sensitivity. Updraft vertical velocities also drive many physical processes essential to numerical weather prediction. Vertical velocities and their role in atmospheric physical processes have been given very limited attention in models for climate and numerical weather prediction. The relevant physical scales range down to tens of meters and are thus frequently sub-grid and require parameterization. Many state-of-science convection parameterizations provide mass fluxes without specifying vertical velocities, and parameterizations that do provide vertical velocities have been subject to limited evaluation against what have until recently been scant observations. Atmospheric observations imply that the distribution of vertical velocities depends on the areas over which the vertical velocities are averaged. Distributions of vertical velocities in climate models may capture this behavior, but it has not been accounted for when parameterizing cloud and precipitation processes in current models. New observations of convective vertical velocities offer a potentially promising path toward developing process-level cloud models and parameterizations for climate and numerical weather prediction. Taking account of the scale dependence of resolved vertical velocities offers a path to matching cloud-scale physical processes and their driving dynamics more realistically, with a prospect of reduced uncertainty in both climate forcing and sensitivity. © 2016 Author(s)."
"55203646000;23866122100;7201689616;","Distributions of Downwelling Radiance at 10 and 20 μm in the High Arctic",2016,"10.1080/07055900.2016.1216825","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987623248&doi=10.1080%2f07055900.2016.1216825&partnerID=40&md5=14429229e36293fff8eee1746de84ac1","In the Arctic, most of the infrared (IR) energy emitted by the surface escapes to space in two atmospheric windows centred at 10 and 20 μm. As the Arctic warms and its water vapour burden increases, the 20 μm cooling-to-space window, in particular, is expected to become increasingly opaque (or “closed”), trapping more IR radiation, with implications for the Arctic’s radiative energy balance. Since 2006, the Canadian Network for the Detection of Atmospheric Change has measured downwelling IR radiation with Atmospheric Emitted Radiance Interferometers at the Polar Environment Atmospheric Research Laboratory at Eureka, Canada, providing measurements of the 10 and 20 μm windows in the High Arctic. In this work, measurements of the distribution of downwelling 10 and 20 µm brightness temperatures at Eureka are separated based on cloud cover, providing a comparison to an existing 10 µm climatology from the Southern Great Plains. The downwelling radiance at both 10 and 20 μm exhibits strong seasonal variability as a result of changes in cloud cover, temperature, and water vapour. Given the 20 µm window’s limited transparency, its ability to allow surface IR radiation to escape to space is found to be highly sensitive to changes in atmospheric water vapour and temperature. When separated by season, brightness temperatures in the 20 µm window are independent of cloud optical thickness in the summer, indicating that this window is opaque in the summer. This may have long-term consequences, particularly as warmer temperatures and increased water vapour “close” the 20 μm window for a prolonged period each year. © 2016 Taylor & Francis."
"57203053317;55931224400;57191498195;6508047932;55444637900;15923105200;","Persistence of orographic mixed-phase clouds",2016,"10.1002/2016GL071036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991104903&doi=10.1002%2f2016GL071036&partnerID=40&md5=6c025125ee684a2c7cc6accd6aedb1a7","Mixed-phase clouds (MPCs) consist of ice crystals and supercooled water droplets at temperatures between 0 and approximately −38°C. They are thermodynamically unstable because the saturation vapor pressure over ice is lower than that over supercooled liquid water. Nevertheless, long-lived MPCs are ubiquitous in the Arctic. Here we show that persistent MPCs are also frequently found in orographic terrain, especially in the Swiss Alps, when the updraft velocities are high enough to exceed saturation with respect to liquid water allowing simultaneous growth of supercooled liquid droplets and ice crystals. Their existence is characterized by holographic measurements of cloud particles obtained at the high-altitude research station Jungfraujoch during spring 2012 and winter 2013 and simulations with the regional climate model COSMO (Consortium of Small-Scale Modeling). ©2016. The Authors."
"30667558200;7003278104;","Characterizing and understanding systematic biases in the vertical structure of clouds in CMIP5/CFMIP2 models",2016,"10.1002/2016GL070515","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991510851&doi=10.1002%2f2016GL070515&partnerID=40&md5=edc77ef71b0c16ad4d8ac42095a4783b","From a traditional low-, middle-, and high-cloud “layered” perspective as well as a more detailed “level” perspective (40 levels), we compare the vertical distribution of clouds in 12 general circulation models (GCMs) against the GCM-Oriented Cloud-Aerosols Lidar and Infrared Pathfinder Satellite Observations Cloud Product (CALIPSO-GOCCP) using a satellite simulator approach. The layered perspective shows that models exhibit the similar regional biases: an overestimate (underestimate) of high clouds over oceans (continents) in the tropics and a strong underestimate of low clouds over stratocumulus regions. Although high clouds are too infrequent on average, the level perspective reveals that high-level clouds fill too many upper levels of the column when present (geometrically too thick), suggesting an overestimation of the cloud overlap. Compositing by dynamical regimes and large-scale relative humidity shows that the models tend to have too many high-level clouds in moist environments and too few boundary layer clouds in dry environments regardless of dynamical regimes. ©2016. American Geophysical Union. All Rights Reserved."
"22980018800;12645767500;6603081424;56567382200;","Interregional differences in MODIS-derived cloud regimes",2016,"10.1002/2016JD025193","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990063416&doi=10.1002%2f2016JD025193&partnerID=40&md5=b55f10ab522e3d1efee20992deeed59b","Cloud regimes based on histogram clustering offer a potentially useful tool for observational analysis of clouds. The utility of the regimes depends on their ability to identify cloud structures that are associated with distinct meteorological conditions. In this study, active remote sensing observations from CloudSat and CALIPSO are binned according to the cloud regimes derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. The occurrence of CloudSat radar reflectivity by altitude, as well as CloudSat-CALIPSO retrievals of cloud cover, precipitation occurrence, cloud radiative effect, and multilayered cloud structure are analyzed for each MODIS cloud regime and for different regions. While the picture of the regimes given by CloudSat and CALIPSO is generally consistent with that derived from MODIS, substantial region-to-region variability is found within the regimes. The regimes constrain the shortwave cloud radiative effect well, while the longwave effect and the precipitation occurrence exhibit more variability. The joint distributions of radar reflectivity and altitude also reveal differences in the structure of clouds within each regime. Thus, it appears that there is region-dependent variability within each regime, resulting from the different meteorological environments. Among the major differences in the cloud structure are cloud top height in convective clouds and the number of distinct cloud layers in boundary layer clouds. Thus, passive optical sensors appear limited in their ability to characterize clouds and assign them to distinct regimes. The differences can be used to estimate the cloud regime inherent variability for studies that use them as a proxy for the climate effects of clouds. © 2016. American Geophysical Union. All Rights Reserved."
"57191486829;22037157600;23096443800;7409322518;","A lagrangian analysis of cold cloud clusters and their life cycles with satellite observations",2016,"10.1002/2016JD025653","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990986072&doi=10.1002%2f2016JD025653&partnerID=40&md5=e959fe269e7588c20a403682a7dfb3d1","Cloud movement and evolution signify the complex water and energy transport in the atmosphere-ocean-land system. Detecting, clustering, and tracking clouds as semicoherent clusters enable study of their evolution which can complement climate model simulations and enhance satellite retrieval algorithms, where there are gaps between overpasses. Using a cluster tracking algorithm, in this study we examine the trajectories, size, and brightness temperature of millions of cloud clusters over their lifespan, from infrared satellite observations at 30 min, 4 kmresolution, for a period of 11 years. We found that the majority of cold clouds were both small and short lived and that their frequency and location are influenced by El Niño. Also, this large sample of individually tracked clouds shows their horizontal size and temperature evolution. Long-lived clusters tended to achieve their temperature and size maturity milestones at different times, while these stages often occurred simultaneously in short-lived clusters. On average, clusters with this lag also exhibited a greater rainfall contribution than those where minimum temperature and maximum size stages occurred simultaneously. Furthermore, by examining the diurnal cycle of cluster development over Africa and the Indian subcontinent, we observed differences in the local timing of the maximum occurrence at different life cycle stages. Over land there was a strong diurnal peak in the afternoon, while over the ocean there was a semidiurnal peak composed of longer-lived clusters in the early morning hours and shorter-lived clusters in the afternoon. Building on regional specific work, this study provides a global long-term survey of object-based cloud characteristics. © 2016. American Geophysical Union. All Rights Reserved."
"7004508767;7501757094;7402359452;36150977900;","Aerosol effects on summer monsoon over Asia during 1980s and 1990s",2016,"10.1002/2016JD025388","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991061362&doi=10.1002%2f2016JD025388&partnerID=40&md5=2a4e05c941e992c3ae3114c005c8cf8f","The Community Earth System Model is used to study the aerosol climate effects during the 1980s and 1990s in which the anthropogenic SO2 emissions decreased in North America and Western Europe and increased in East and South Asia. From the 100 year simulations, aerosol forcing results in cooler (-0.13 K) and drier (-0.01 mm/day) atmosphere with less shortwave radiation flux at the surface (-0.37W/m2). The clear-sky shortwave radiation flux decreased over East Asia (-0.81W/m2) and South Asia (-1.09W/m2), but increased over Western Europe (+1.16 W/m2) and North America (+0.39W/m2), consistent with aerosol loading changes. While changes in spatial distributions of all-sky shortwave radiation and surface temperature are closely related to cloud changes, the changes in wind and precipitation do not correspond to aerosol loading changes, indicating the complexity of aerosol-cloud circulation interactions. The East and South Asia monsoons were generally weakened due mainly to southward shift of the 200 hPa East Asia Jet (EAJ) and decrease in 850 hPa winds; annual precipitation decreased by 2% in South Asia but increased by 2% in Yangtze-Huai River Valley over East Asia. The uncertainties associated with aerosol climate effects are addressed within the context of model variability and the global warming effect. For the latter, while the aerosol effects decrease the greenhouse warming on the global mean, the regional responses are different. Nevertheless, the characteristics of aerosol climate effects, including the southward 200 hPa EAJ and weakened South Asia monsoon, still persist when the climate becomes warmer, although the strength and the geographical distribution are slightly modulated. © 2016. American Geophysical Union. All Rights Reserved."
"16678344600;7201906656;25824453700;7004862771;","Fragmented patterns of flood change across the United States",2016,"10.1002/2016GL070590","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990967326&doi=10.1002%2f2016GL070590&partnerID=40&md5=03fe5a9f3d8b02f8ce84185b4f15860c","Trends in the peak magnitude, frequency, duration, and volume of frequent floods (floods occurring at an average of two events per year relative to a base period) across the United States show large changes; however, few trends are found to be statistically significant. The multidimensional behavior of flood change across the United States can be described by four distinct groups, with streamgages experiencing (1) minimal change, (2) increasing frequency, (3) decreasing frequency, or (4) increases in all flood properties. Yet group membership shows only weak geographic cohesion. Lack of geographic cohesion is further demonstrated by weak correlations between the temporal patterns of flood change and large-scale climate indices. These findings reveal a complex, fragmented pattern of flood change that, therefore, clouds the ability to make meaningful generalizations about flood change across the United States. ©2016. The Authors."
"9249239700;36150977900;57144839900;57203722524;56130997600;56618531600;6603126554;36899513900;7005528388;","Assessing the radiative impacts of precipitating clouds on winter surface air temperatures and land surface properties in general circulation models using observations",2016,"10.1002/2016JD025175","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991108747&doi=10.1002%2f2016JD025175&partnerID=40&md5=faf38da2413b10244fa0d3da04c3b5bc","Using CloudSat-CALIPSO ice water, cloud fraction, and radiation; Clouds and the Earth’s Radiant Energy System (CERES) radiation; and long-term station-measured surface air temperature (SAT), we identified a substantial underestimation of the total ice water path, total cloud fraction, land surface radiative flux, land surface temperature (LST), and SAT during Northern Hemisphere winter in Coupled Model Intercomparison Project Phase 5 (CMIP5) models. We perform sensitivity experiments with the National Center for Atmospheric Research (NCAR) Community Earth System Model version 1 (CESM1) in fully coupled modes to identify processes driving these biases. We found that biases in land surface properties are associated with the exclusion of downwelling longwave heating from precipitating ice during Northern Hemisphere winter. The land surface temperature biases introduced by the exclusion of precipitating ice radiative effects in CESM1 and CMIP5 both spatially correlate with winter biases over Eurasia and North America. The underestimated precipitating ice radiative effect leads to colder LST, associated surface energy-budget adjustments, and cooler SAT. This bias also shifts regional soil moisture state from liquid to frozen, increases snow cover, and depresses evapotranspiration (ET) and total leaf area index in Northern Hemisphere winter. The inclusion of the precipitating ice radiative effects largely reduces the model biases of surface radiative fluxes (more than 15Wm-2), SAT (up to 2-4K), and snow cover and ET (25-30%), compared with those without snow-radiative effects. © 2016. American Geophysical Union. All Rights Reserved."
"57188594058;35578543700;6701670597;","Convectively coupled Kelvin waves in aquachannel simulations: 2. Life cycle and dynamicalconvective coupling",2016,"10.1002/2016JD025022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991067535&doi=10.1002%2f2016JD025022&partnerID=40&md5=6913197dc3f6d4a604167ecfebe01120","This second part of a two-part study uses Weather Research and Forecasting simulations with aquachannel and aquapatch domains to investigate the time evolution of convectively coupled Kelvin waves (CCKWs). Power spectra, filtering, and compositing are combined with object-tracking methods to assess the structure and phase speed propagation of CCKWs during their strengthening, mature, and decaying phases. In this regard, we introduce an innovative approach to more closely investigate the wave (Kelvin) versus entity (super cloud cluster or “SCC”) dualism. In general, the composite CCKW structures represent a dynamical response to the organized convective activity. However, pressure and thermodynamic fields in the boundary layer behave differently. Further analysis of the time evolution of pressure and low-level moist static energy finds that these fields propagate eastward as a “moist” Kelvin wave (MKW), faster than the envelope of organized convection or SCC. When the separation is sufficiently large the SCC dissipates, and a newSCC generates to the east, in the region of strongest negative pressure perturbations. We revisit the concept itself of the “coupling” between convection and dynamics, and we also propose a conceptual model for CCKWs, with a clear distinction between the SCC and the MKW components. © 2016. American Geophysical Union. All Rights Reserved."
"57191658356;15724418700;6701573532;","Evolution of the upper-level thermal structure in tropical cyclones",2016,"10.1002/2016GL070622","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992365185&doi=10.1002%2f2016GL070622&partnerID=40&md5=712410aee24373c13db54b811513650e","Tropical cyclones (TCs) are associated with tropopause-level cooling above tropospheric warming. We collect temperature retrievals from 2007 to 2014 near worldwide hurricane-strength TCs using three remote sensing platforms: the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), the Advanced Microwave Sounding Unit-A (AMSU-A), and geostationary infrared (IR) imagery. These retrievals are composited about the lifetime maximum intensity (LMI) to examine the evolution of the fine-scale temperature structure within TCs. The convective structure evolves highly asymmetrically about LMI, while intensity evolution shows a much weaker degree of asymmetry. Relative to the far-field structure, tropopause-level cooling occurs before a tropospheric warm core is established. We speculate that the associated convective destabilization exerts a positive feedback on TC development by increasing the depth of existing convection. Tropopause-level cold anomalies move away from the storm after LMI, potentially increasing the near-surface horizontal pressure gradient toward the storm center and increasing the maximum winds. ©2016. American Geophysical Union. All Rights Reserved."
"55871244200;12241162500;57189904335;55485614900;57210353005;6602573212;","Coexisting responses in tree-ring δ13C to high-latitude climate variability under elevated CO2: A critical examination of climatic effects and systematic discrimination rate changes",2016,"10.1016/j.agrformet.2016.06.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975893840&doi=10.1016%2fj.agrformet.2016.06.005&partnerID=40&md5=85ccb80a5e79138852b63afc99eaf30e","Dendroclimatic methods may quantify a factor or factors affecting δ13C fractionation and thus help to reveal the signals archived in dendroisotope records over the long term. Gathering evidence suggests a repertoire of limitations for photosynthesis to occur, with an increasing possibility that more than one external factor may control the assimilation rate and thus the tree-ring δ13C variations. Here we show that such a situation conceivably describes the tree-ring δ13C data from northern timberline and further illustrate the use of dendroclimatic analyses in separating the coexisting signals in dendroisotope data. While the assimilation rate was primarily controlled by a photon flux, thereby allowing the tree-ring δ13C to provide a proxy for past variations in irradiance, there was some evidence that also a temperature signal is directly present in the tree-ring δ13C data, not merely as a function of an indirect correlate reflecting its interplay between sunshine/cloud cover. Over the period common to all instrumental records (1971–2011), both the sunshine hours and global radiation influenced the δ13C from mid-June to mid-July, whereas the mean maximum temperatures (TMAX) showed an impact on δ13C from mid-July to mid-August. We assume that these climatic associations represent mainly non-stomatal limitations to assimilation rate. Possibly, this response may involve the mesophyll conductance to CO2 transfer from intercellular spaces to chloroplasts, a factor found previously to pose a temperature responsive limitation to photosynthesis. After correction for the Suess effect, the δ13C chronology exhibited a long-term decline attributable to discrimination rate changes under elevated atmospheric CO2 concentration. We make a methodological contribution by comparing the various methods available from literature for estimating the magnitude of this bias in the δ13C chronology. The robustness of the results indicated that this data shortcoming is not critical but can be corrected. The method inter-comparisons yielded very similar results, near the previously suggested change in discrimination of 0.0073‰ per ppmv CO2. We recommend comparative assessments of discrimination rate change to be combined with dendroclimatic analysis. © 2016 Elsevier B.V."
"56157868600;56118407000;24331295800;6701895637;","Improving satellite-retrieved surface radiative fluxes in polar regions using a smart sampling approach",2016,"10.5194/tc-10-2379-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991695761&doi=10.5194%2ftc-10-2379-2016&partnerID=40&md5=fb4a839dd9a8f7ee505844bc37a3d93c","The surface energy budget (SEB) of polar regions is key to understanding the polar amplification of global climate change and its worldwide consequences. However, despite a growing network of ground-based automatic weather stations that measure the radiative components of the SEB, extensive areas remain where no ground-based observations are available. Satellite remote sensing has emerged as a potential solution to retrieve components of the SEB over remote areas, with radar and lidar aboard the CloudSat and CALIPSO satellites among the first to enable estimates of surface radiative long-wave (LW) and short-wave (SW) fluxes based on active cloud observations. However, due to the small swath footprints, combined with a return cycle of 16 days, questions arise as to how CloudSat and CALIPSO observations should be optimally sampled in order to retrieve representative fluxes for a given location. Here we present a smart sampling approach to retrieve downwelling surface radiative fluxes from CloudSat and CALIPSO observations for any given land-based point-of-interest (POI) in polar regions. The method comprises a spatial correction that allows the distance between the satellite footprint and the POI to be increased in order to raise the satellite sampling frequency. Sampling frequency is enhanced on average from only two unique satellite overpasses each month for limited-distance sampling &lt; 10 km from the POI, to 35 satellite overpasses for the smart sampling approach. This reduces the root-mean-square errors on monthly mean flux estimates compared to ground-based measurements from 23 to 10 W m-2 (LW) and from 43 to 14 W m-2 (SW). The added value of the smart sampling approach is shown to be largest on finer temporal resolutions, where limited-distance sampling suffers from severely limited sampling frequencies. Finally, the methodology is illustrated for Pine Island Glacier (Antarctica) and the Greenland northern interior. Although few ground-based observations are available for these remote areas, important climatic changes have been recently reported. Using the smart sampling approach, 5-day moving average time series of downwelling LW and SW fluxes are demonstrated. We conclude that the smart sampling approach may help to reduce the observational gaps that remain in polar regions to further refine the quantification of the polar SEB. © 2016 Author(s)."
"24334289200;7004337213;","A first-order assessment of direct aerosol radiative effect in the southeastern U.S. using over a decade long multisatellite data record",2016,"10.4137/ASWR.S39226","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84991245888&doi=10.4137%2fASWR.S39226&partnerID=40&md5=e204e377784bb7ddc355327d0635daa3","Aerosols comprise a critical portion of the Earth’s climate due to their radiative properties. More emphasis is now being placed upon understanding radiative effects of aerosols on a regional scale. The primary goal of this research is to estimate the aerosol direct radiative effect (DRE) and examine its dynamical nature in the Southeastern U.S. based on satellite data obtained from the moderate-resolution imaging spectroradiometer (MODIS) and multi-angle imaging spectroradiometer (MISR) instruments onboard the Terra satellite from 2000 to 2011. This 12-year analysis utilizes satellite measurements of aerosol optical depth (AOD), surface albedo, cloud fraction, and single-scattering albedo over the Southeastern U.S. as inputs to a first-order approximation of regional top of the atmosphere DRE. Results indicate that AOD is the primary driver of DRE estimates, with surface albedo and singlescattering albedo having some appreciable effects as well. During the cooler months, the minima (less negative) of DRE vary between-6 and-3 W/m2, and during the warmer months, there is more variation with DRE maxima varying between-24 and-12.6 W/m2 for MODIS and-22.5 and-11 W/m2 for MISR. Yet if we take an average of the monthly DRE over time (12 years), we estimate ΔF =-7.57 W/m2 for MODIS and ΔF =-5.72 W/m2 for MISR. Regional assessments of the DRE show that background levels of DRE are similar to the 12-year average of satellite-based DRE, with urbanized areas having increased levels of DRE compared to background conditions. Over the study period, DRE has a positive trend (becoming less negative), which implies that the region could lose this protective top of the atmosphere cooling with the advancement of climate change impacting the biogenic emissions of aerosols. © the authors, publisher and licensee Libertas Academica Limited."
"13405561000;8918407000;35104877900;36655323000;9838847000;","Changes in marine fog in a warmer climate",2016,"10.1002/asl.691","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984678066&doi=10.1002%2fasl.691&partnerID=40&md5=d379edaefae7deb88b08bc6ff00f8d1d","Changes in marine fog in a warmer climate are investigated through simulations using the atmospheric component of a global climate model, with both observed and perturbed sea surface temperature forcing. Global changes in marine fog occurrence in different seasons are compared. We show that the changes in marine fog occurrence correspond well to changes in horizontal temperature advection near the surface in a warmer climate. Therefore, the changes in marine fog can be well explained by large-scale circulation changes. Regarding changes in the characteristics of marine fog, we show that the in-cloud liquid water content of marine fog is consistently increased in a warmer climate, for a given horizontal surface temperature advection. It is also confirmed that the contribution of changes in marine fog to cloud feedback is not negligible, but is small. © 2016 The Authors. Atmospheric Science Letters published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"56512568900;15031489000;56010809300;36841079300;","Moving SWAT model calibration and uncertainty analysis to an enterprise Hadoop-based cloud",2016,"10.1016/j.envsoft.2016.06.024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977611080&doi=10.1016%2fj.envsoft.2016.06.024&partnerID=40&md5=ec2ea4d3e2fe86b6af7c6bc5e713a197","With enhanced availability of high spatial resolution data, hydrologic models such as the Soil and Water Assessment Tool (SWAT) are increasingly used to investigate effects of management activities and climate change on water availability and quality. The advantages come at a price of greater computational demand and run time. This becomes challenging to model calibration and uncertainty analysis as these routines involve a large number of model runs. For efficient modelling, a cloud-based Calibration and Uncertainty analysis Tool for SWAT (CUT-SWAT) was implemented using Hadoop, an open source cloud platform, and the Generalized Likelihood Uncertainty Estimation method. Test results on an enterprise cloud showed that CUT-SWAT can significantly speedup the calibration and uncertainty analysis processes with a speedup of 21.7–26.6 depending on model complexity and provides a flexible and fault-tolerant model execution environment (it can gracefully and automatically handle partial failure), thus would be an ideal method to solve computational demand problems in hydrological modelling. © 2016 Elsevier Ltd"
"55738957800;57203012011;11839267100;24173681800;","Estimation of convective entrainment properties from a cloud-resolving model simulation during TWP-ICE",2016,"10.1007/s00382-015-2957-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84952666613&doi=10.1007%2fs00382-015-2957-7&partnerID=40&md5=eaaddac42204f4dceaf7f10df8c8f760","The fractional entrainment rate in convective clouds is an important parameter in current convective parameterization schemes of climate models. In this paper, it is estimated using a 1-km-resolution cloud-resolving model (CRM) simulation of convective clouds from TWP-ICE (the Tropical Warm Pool-International Cloud Experiment). The clouds are divided into different types, characterized by cloud-top heights. The entrainment rates and moist static energy that is entrained or detrained are determined by analyzing the budget of moist static energy for each cloud type. Results show that the entrained air is a mixture of approximately equal amount of cloud air and environmental air, and the detrained air is a mixture of ~80 % of cloud air and 20 % of the air with saturation moist static energy at the environmental temperature. After taking into account the difference in moist static energy between the entrained air and the mean environment, the estimated fractional entrainment rate is much larger than those used in current convective parameterization schemes. High-resolution (100 m) large-eddy simulation of TWP-ICE convection was also analyzed to support the CRM results. It is shown that the characteristics of entrainment rates estimated using both the high-resolution data and CRM-resolution coarse-grained data are similar. For each cloud category, the entrainment rate is high near cloud base and top, but low in the middle of clouds. The entrainment rates are best fitted to the inverse of in-cloud vertical velocity by a second order polynomial. © 2015, Springer-Verlag Berlin Heidelberg."
"56449414100;8105442200;56449398300;55290356700;","Climate sensitivity characteristics of tropical cirrus clouds using lidar measurements",2016,"10.1117/1.JRS.10.046005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994475033&doi=10.1117%2f1.JRS.10.046005&partnerID=40&md5=d5c7927c686dc7cebafc9acb1f3843f3","Cirrus clouds play an important role in the Earth's radiation budget due to their high frequency of occurrence, nonspherical ice crystal formations, and variability in scattering/absorption characteristics. Mostly, tropical cirrus clouds are considered greenhouse modulators. Thus, the parameterization of tropical cirrus clouds in terms of their microphysical properties and the corresponding radiative effects are highly important for climate studies. For characterizing the radiative properties of cirrus clouds, which depend on the size, shape, and number of ice crystals, knowledge of the extinction coefficient (σ) and optical depth (τ) is necessary. σ provides information needed for understanding the influence of the scatterers on the radiative budget, whereas τ gives an indication of the composition and thickness of the cloud. Extensive research on tropical cirrus clouds has been carried out by using ground-based lidar (GBL) and satellite-based lidar systems. The characteristics of tropical cirrus clouds derived by using the data from the GBL system over the tropical site Gadanki (13.5° N, 79.2° E), India, during 2010 are presented. Some of the results are compared with those obtained by us from satellite-based cloud-aerosol lidar with orthogonal polarization observations of the cloud-aerosol lidar and infrared pathfinder satellite observation mission. It is observed that there is a strong dependence on some of the physical properties, such as occurrence height, cloud temperature, and geometrical thickness, and on the microphysical parameters in terms of extinction coefficient and optical depth. The correlation of both σ and τ with temperature is also observed. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)."
"8871497700;7006146719;6602515941;25825715600;57192091713;55629222300;22236015300;7402781278;23668415500;7102643810;7005071296;7410177774;10640192200;57192169322;7003750797;24169741400;8568391400;55682775100;24480463300;7006821210;55951906300;14024872700;8927405700;8705440100;36076994600;24491934500;7007162501;7006599647;6506254483;6504212618;13204389400;","A field campaign to elucidate the impact of biogenic aerosols on clouds and climate",2016,"10.1175/BAMS-D-14-00199.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84999122281&doi=10.1175%2fBAMS-D-14-00199.1&partnerID=40&md5=d5b2511be0eb73ee3cf0e7cd6ed6f0b5","Observations obtained during an 8-month deployment of AMF2 in a boreal environment in Hyytiälä, Finland, and comprehensive in situ data from the SMEAR II station enable the characterization of biogenic aerosol, clouds, and precipitation and their interactions. © 2016 American Meteorological Society."
"56244941200;8686542400;7005601387;7005063377;","Relevance of long term time – Series of atmospheric parameters at a mountain observatory to models for climate change",2016,"10.1016/j.jastp.2016.08.002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981531528&doi=10.1016%2fj.jastp.2016.08.002&partnerID=40&md5=18a709b68494a4b7d2ca5c284c85df74","A detailed analysis has been made based on annual meteorological and cosmic ray data from the Lomnicky stit mountain observatory (LS, 2634 masl; 49.40°N, 20.22°E; vertical cut-off rigidity 3.85 GV), from the standpoint of looking for possible solar cycle (including cosmic ray) manifestations. A comparison of the mountain data with the Global average for the cloud cover in general shows no correlation but there is a possible small correlation for low clouds (LCC in the Global satellite data). However, whereas it cannot be claimed that cloud cover observed at Lomnicky stit (LSCC) can be used directly as a proxy for the Global LCC, its examination has value because it is an independent estimate of cloud cover and one that has a different altitude weighting to that adopted in the satellite-derived LCC. This statement is derived from satellite data (http://isccp.giss.nasa.gov/climanal7.html) which shows the time series for the period 1983–2010 for 9 cloud regimes. There is a significant correlation only between cosmic ray (CR) intensity (and sunspot number (SSN)) and the cloud cover of the types cirrus and stratus. This effect is mainly confined to the CR intensity minimum during the epoch around 1990, when the SSN was at its maximum. This fact, together with the present study of the correlation of LSCC with our measured CR intensity, shows that there is no firm evidence for a significant contribution of CR induced ionization to the local (or, indeed, Global) cloud cover. Pressure effects are the preferred cause of the cloud cover changes. A consequence is that there is no evidence favouring a contribution of CR to the Global Warming problem. Our analysis shows that the LS data are consistent with the Gas Laws for a stable mass of atmosphere. © 2016 Elsevier Ltd"
"24399273600;16066726600;6602605094;24778896100;","3D reconstruction of tropospheric cirrus clouds",2016,"10.1016/j.asr.2016.06.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983035365&doi=10.1016%2fj.asr.2016.06.011&partnerID=40&md5=2f78303e484eb687ab50dd51ec9983a8","In this paper, we present a series of results from stereo-imagery of cirrus clouds in the troposphere. These clouds are either of natural origin or are created by aircraft exhausts. They are presently considered to be a major cause for the climate change. Two observation campaigns were conducted in France in 2013 and 2014. The observing sites were located in Marnay (47°17′31.5″ N, 5°44′58.8″ E; altitude 275 m) and in Mont Poupet (46°58′31.5″ N, 5°52′22.7″ E; altitude 600 m). The distance between both sites was 36 km. We used numeric CMOS photographic cameras. The image processing sequence included a contrast enhancement and a perspective inversion to obtain a satellite-type view. Finally, the triangulation procedure was used in an area that is a common part of both fields of view. © 2016 COSPAR"
"55796506900;56276311500;42263280300;56068376200;16402988900;","The updated effective radiative forcing of major anthropogenic aerosols and their effects on global climate at present and in the future",2016,"10.1002/joc.4613","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956620939&doi=10.1002%2fjoc.4613&partnerID=40&md5=2b1a8f7aed9ab19dea34c3253d557c9b","The effective radiative forcing (ERF), as newly defined in the Intergovernmental Panel on Climate Change's Fifth Assessment Report (IPCC AR5), of three anthropogenic aerosols [sulphate (SF), black carbon (BC), and organic carbon (OC)] and their comprehensive climatic effects were simulated and discussed, using the updated aerosol-climate online model of BCC_AGCM2.0.1_CUACE/Aero. From 1850 to 2010, the total ERF of these anthropogenic aerosols was −2.49 W m−2, of which the aerosol–radiation interactive ERF (ERFari) and aerosol–cloud interactive ERF (ERFaci) were ∼ −0.30 and −2.19 W m−2, respectively. SF was the largest contributor to the total ERF, with an ERF of −2.37 W m−2. The ERF of BC and OC were 0.12 and −0.31 W m−2, respectively. From 1850 to 2010, anthropogenic aerosols brought about a decrease of ∼2.53 K and ∼0.20 mm day−1 in global annual mean surface temperature and precipitation, respectively. Surface cooling was most obvious over mid- and high latitudes in the northern hemisphere (NH). Precipitation change was most pronounced near the equator, with decreased and increased rainfall to the north and south of the equator, respectively; this might be largely related to the enhanced Hadley Cell in the NH. Relative humidity near surface was increased, especially over land, due to surface cooling induced by anthropogenic aerosols. Cloud cover and water path were increased, especially in or near the source regions of anthropogenic aerosols. Experiments based on the Representative Concentration Pathway (RCP) 4.5 given in IPCC AR5 shows the dramatic decrease in three anthropogenic aerosols in 2100 will lead to an increase of ∼2.06 K and 0.16 mm day−1 in global annual mean surface temperature and precipitation, respectively, compared with those in 2010. © 2016 Royal Meteorological Society"
"55326237100;57205355972;7102591209;35227762400;6701422868;","A methodology for simultaneous retrieval of ice and liquid water cloud properties. Part 2: Near-global retrievals and evaluation against A-Train products",2016,"10.1002/qj.2889","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85004010290&doi=10.1002%2fqj.2889&partnerID=40&md5=f5d3e71e34944a5b06d1b3184ecabbd6","This article presents results of a novel methodology capable of simultaneously retrieving optical and microphysical properties of multi-level ice and liquid clouds. The method was introduced in Part I, which theoretically demonstrated its capabilities, and its results are here analysed and evaluated against A-Train operational products. In addition to being robust to multi-layer conditions, another advantage of the method is that rigorous uncertainties and analysis tools are attached to its retrievals. Also, the combined use of short-wave and thermal infrared channels provides a wide range of sensitivity from moderately thin to thick ice cloud layers. Finally, the method is also novel in that the ice water path (IWP) is directly retrieved. These new retrievals should therefore be useful in providing new data for evaluating climate model predictions of IWP. In this study, our methodology has been applied to one year of A-Train measurements, narrowed to daytime conditions over oceanic surfaces. The retrievals and their uncertainties are statistically analysed, after a thorough discussion of the filtering process. It appears that our method is sensitive to IWPs ranging between about 0.5 and 1000 g m−2, with uncertainties better than 25% between 5 and 500 g m−2. Retrievals of the optical depth and effective radius of liquid layers have uncertainties better than 20%. Our retrievals are then compared to five independent operational A-Train products. Very good agreements, well within a factor of 2, are found by comparisons to products from active and passive instruments. These results overall lead to the validation of our method. Additionally, the robustness of passive operational products to multi-layer conditions is discussed. Preliminary comparisons show a possible overestimation of retrievals obtained under the single-layer approximation. A thorough assessment of this problem will be addressed in a following study. © 2016 The Authors and Crown copyright, Met Office. Quarterly Journal of the Royal Meteorological Society published by John Wiley © Sons Ltd on behalf of the Royal Meteorological Society."
"6602801093;7101638860;14024927800;","Modelling wet deposition in simulations of volcanic ash dispersion from hypothetical eruptions of Merapi, Indonesia",2016,"10.1016/j.atmosenv.2016.08.022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983546630&doi=10.1016%2fj.atmosenv.2016.08.022&partnerID=40&md5=9d88d495f68c10a4b643118b3d7acc3c","The statistical impact of including the process of wet deposition in dispersion model predictions of the movement of volcanic ash is assessed. Based on hypothetical eruptions of Merapi, Indonesia, sets of dispersion model simulations were generated, each containing four simulations per day over a period of three years, to provide results based on a wide range of atmospheric conditions. While on average dry sedimentation removes approximately 10% of the volcanic ash from the atmosphere during the first 24 h, wet deposition removes an additional 30% during seasons with highest rainfall (December and January) but only an additional 1% during August and September. The majority of the wet removal is due to in-cloud rather than below-cloud collection of volcanic ash particles. The largest uncertainties in the amount of volcanic ash removed by the process of wet deposition result from the choice of user-defined parameters used to compute the scavenging coefficient, and from the definition of the cloud top height. Errors in the precipitation field provided by the numerical weather prediction model utilised here have relatively less impact. © 2016"
"25926762100;23484340400;14045744500;7003570692;","Towards retrieving critical relative humidity from ground-based remote-sensing observations",2016,"10.1002/qj.2874","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983523246&doi=10.1002%2fqj.2874&partnerID=40&md5=f5d78eb96c3eb27b26f4b2f0920378a4","Nearly all large-scale cloud parametrizations require the specification of the critical relative humidity (RHcrit). This is the grid-box mean relative humidity at which the subgrid fluctuations in temperature and water vapour are assumed to become so large that part of a subsaturated grid box becomes saturated and cloud starts to form. Until recently, the lack of high-resolution observations of temperature and moisture variability has hindered achievement of a reasonable estimate of RHcrit. However, the advent of ground-based Raman lidar now allows the acquisition of long records of temperature and moisture with subminute sample rates. Lidar observations are inherently noisy and any analysis of higher-order moments will be dependent on the ability to quantify and remove this noise. We present an exploratory study aimed at understanding whether current noise levels of lidar-retrieved temperature and water vapour are sufficiently low to obtain a reasonable estimate of RHcrit. We show that vertical profiles of RHcrit can be derived with an uncertainty of a few per cent. RHcrit tends to be smallest near the boundary-layer top and seems to be insensitive to the horizontal grid spacing at the scales investigated here (30–120 km). However, larger sensitivity was found to the vertical grid spacing. RHcrit is observed to decrease by 10% as the vertical grid spacing quadruples. By way of example, the lidar-retrieved RHcrit profiles were used to evaluate a parametrization that estimates RHcrit from variances diagnosed from the boundary-layer parametrization. It is shown that this parametrization overestimates RHcrit by up to 10%, but captures the diurnal variability of RHcrit well, with lower values of RHcrit near the boundary-layer top. While we show that the uncertainties associated with the retrievals are large, lidar observations seem promising to diagnose and evaluate a very important parameter to predict cloud fraction in climate and numerical weather prediction models. © 2016 Royal Meteorological Society and Crown Copyright, Met Office. Quarterly Journal of the Royal Meteorological Society © 2016 Royal Meteorological Society"
"7103056879;8528988800;17435538500;","Statistical characterization of cloud-to-ground lightning data and meteorological modelling of cloud-to-ground lightning days for the warm season in the province of León (northwest Spain)",2016,"10.1002/met.1590","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85002643756&doi=10.1002%2fmet.1590&partnerID=40&md5=58a166e2d1739ce2b6e81d0c7c0ad9da","This study presents the characteristics of cloud-to-ground lightning in the province of León (Spain), based on data collected via the lightning detection network of the Spanish Meteorological Agency. A total of 146 081 flashes and 279 220 strokes were recorded between 2000 and 2010. Spatial analysis (total, negative and positive flash density, and mean peak currents of positive and negative flashes) was performed at a resolution of 1 km. The maximum density recorded for total negative and positive flashes was 2.0 flashes km−2 year−1; 2.3 for negative flashes only and 0.178 for positive flashes. There was a different spatial distribution for positive compared with negative flashes, resulting from meteorological mechanisms involved with their polarities. The density distribution corresponding to both total and negative flashes appears to be clearly associated with topography. Interestingly, there is a clear inverse spatial correlation between the density and peak current parameters, which has important implications for constructing risk maps of lightning activity. This correlation has been quantified and confirmed for both positive and negative flashes by two separate regression equations. In the second part of the present study, a statistical model was constructed to predict lightning in the province of León, using a quadratic discriminant function that encompasses three meteorological variables obtained from National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis: lifted index, K-index and precipitable water. To construct the model, data were used from May to September over 2002–2007, and then applied to an independent sample of years from 2008 to 2010. Results were verified using skill scores probability of detection, false alarm rate, critical success index and true skill statistic. Scores obtained for the samples were 0.79, 0.45, 0.48 and 0.53 (respectively) for model construction, and 0.78, 0.14, 0.69 and 0.65 (respectively) for application to the independent sample. © 2016 Royal Meteorological Society"
"56562591400;8667741900;7004890337;","Temporal variability in the Antarctic Polar Front (2002–2014)",2016,"10.1002/2016JC012145","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990231924&doi=10.1002%2f2016JC012145&partnerID=40&md5=95617051f93b23627b1e56dbd11a4b0b","We investigate intraannual to interannual variability in the Antarctic Polar Front (PF) using weekly PF realizations spanning 2002–2014 (found at doi.pangaea.de/10.1594/PANGAEA.855640). While several PF studies have used gradient maxima in sea surface temperature (SST) or height to define its location, results from this study are based on a PF defined using SST measurements that avoid cloud contamination and the influence of steric sea level change. With a few regional exceptions, we find that the latitudinal position of the PF does not vary seasonally, yet its temperature exhibits a clear seasonal cycle. Consistent with previous studies, the position and intensity of the PF is largely influenced by bathymetry; generally, over steep topography, we find that the front intensifies and interannual variability in its position is low. We also investigate drivers of PF variability in the context of large-scale climate variability on various spatial and temporal scales, but find that the major modes of Southern Hemisphere climate variability explain only a tiny fraction of the interannual PF variance. Over the study time period, the PF intensifies at nearly all longitudes while exhibiting no discernible meridional displacement in its zonal mean path. © 2016. American Geophysical Union. All Rights Reserved."
"56655885600;56979660100;57194346960;7404011405;","Changes in mountain glaciers, lake levels, and snow coverage in the Tianshan monitored by GRACE, ICESat, altimetry, and MODIS",2016,"10.3390/rs8100798","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019731021&doi=10.3390%2frs8100798&partnerID=40&md5=e37ca42387c94b854b7ff6379b7ee850","The Tianshan mountain range is experiencing a notable environmental change as a result of global warming. In this paper; we adopt multiple remote sensing techniques to examine the diversified geophysical changes in the Tianshan; including glacier changes measured by Gravity Recovery and Climate Experiment (GRACE) and Ice, Cloud, and land Elevation Satellite (ICESat); lake level changes measured by radar altimetry; and snow coverage measured by moderate-resolution imaging spectroradiometer (MODIS). We find a rapid transition from dry years to wet years in 2010 in the western and northern Tianshan for all the geophysical measurements. The transition is likely caused by increasing westerlies and greatly pollutes the gravity signals in the edge of Tianshan. However, glaciers in the central Tianshan are unaffected and have been steadily losing mass at a rate of -4.0 ± 0.7 Gt/year during 2003-2014 according to space gravimetry and -3.4 ± 0.8 Gt/year during 2003-2009 according to laser altimetry. Our results show a weaker declining trend and greater linearity compared with earlier estimates; because we investigate the signal pattern in more detail. Finally; water level records of 60 years in Bosten Lake; China; are presented to show that for areas strongly dependent on meltwater; rising temperature can benefit the water supply in the short run; but cause it to deteriorate in the long run. © 2016 by the authors."
"36904222100;7402859325;","Aerosol vertical distribution over east China from RIEMS-Chem simulation in comparison with CALIPSO measurements",2016,"10.1016/j.atmosenv.2016.08.045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983393846&doi=10.1016%2fj.atmosenv.2016.08.045&partnerID=40&md5=bf8a5c30752f147f8150fb4637a58a1a","The horizontal and vertical distributions of aerosol extinction coefficient (AEC) and mass concentration over east China in October 2010 were investigated by using an online-coupled regional climate model and CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) data. Model performance was evaluated comprehensively against ground observations of meteorological variables and PM10 concentrations and CALIPSO retrieved AEC profiles, which demonstrated a good ability of the model in simulating spatial distribution and evolution of aerosol concentration and optical properties. Severe pollution episodes were found over wide areas of east China during the study period, with the maximum mean PM10 concentration exceeding 200 μg m−3 in the Chongqing district and a part of the lower reaches of the Yellow River on 8–10 October. Both CALIPSO retrievals and model simulations revealed high AEC values (≥1 km−1) often occurred within 2 km above ground over most areas of east China. AEC vertical profile in or in the vicinity of China major cities along CALIPSO orbit track exhibited two typical features: one was AEC reached its maximum (∼4 km−1) near the surface (&lt;200 m) and decreased rapidly to &lt; 0.1 km−1 at altitudes above 1 km, another one was AEC peaked at higher altitudes of about 0.5–1 km with a maximum up to 3 km−1. AEC vertical profile was strongly dependent on vertical distribution of both aerosol concentration, composition and relative humidity. The vertical cross sections over typical regions of east China exhibited a decreasing AEC in magnitude from the continent to the China seas. Over the continent, AEC was either maximum near the surface or peaked at higher altitudes (0.5–1.0 km) due to increases of relative humidity or aerosol concentration in those regions, whereas over the seas of China, AEC profile was characterized by peak values at an altitude around 1 km, mainly due to an elevated relative humidity there, which favored rapid aerosol hygroscopic growth and consequently AEC increase. © 2016 Elsevier Ltd"
"55809947500;36018685200;55619292519;57054708700;8579817500;","Automatic scaling hadoop in the cloud for efficient process of big geospatial data",2016,"10.3390/ijgi5100173","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994115645&doi=10.3390%2fijgi5100173&partnerID=40&md5=0bfef29f52705543c200ef1a1e565c0f","Efficient processing of big geospatial data is crucial for tackling global and regional challenges such as climate change and natural disasters, but it is challenging not only due to the massive data volume but also due to the intrinsic complexity and high dimensions of the geospatial datasets. While traditional computing infrastructure does not scale well with the rapidly increasing data volume, Hadoop has attracted increasing attention in geoscience communities for handling big geospatial data. Recently, many studies were carried out to investigate adopting Hadoop for processing big geospatial data, but how to adjust the computing resources to efficiently handle the dynamic geoprocessing workload was barely explored. To bridge this gap, we propose a novel framework to automatically scale the Hadoop cluster in the cloud environment to allocate the right amount of computing resources based on the dynamic geoprocessing workload. The framework and auto-scaling algorithms are introduced, and a prototype system was developed to demonstrate the feasibility and efficiency of the proposed scaling mechanism using Digital Elevation Model (DEM) interpolation as an example. Experimental results show that this auto-scaling framework could (1) significantly reduce the computing resource utilization (by 80% in our example) while delivering similar performance as a full-powered cluster; and (2) effectively handle the spike processing workload by automatically increasing the computing resources to ensure the processing is finished within an acceptable time. Such an auto-scaling approach provides a valuable reference to optimize the performance of geospatial applications to address data- and computational-intensity challenges in GIScience in a more cost-efficient manner."
"56979660100;56655885600;7404011405;","The changing pattern of lake and its contribution to increased mass in the Tibetan Plateau derived from GRACE and ICESat data",2016,"10.1093/gji/ggw293","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988710083&doi=10.1093%2fgji%2fggw293&partnerID=40&md5=1318eaf2408233ff71de2869e54e39bd","This paper compares GRACE (Gravity Recovery and Climate Experiment) and ICESat (Ice, Cloud and land Elevation Satellite) observations to confirm whether the observed gravity increase in the Tibetan Plateau (TP) was primarily caused by lake storage gain, and comprehensively analyses the changing pattern of lake level over 2003-2009. An improved automated method was used to obtain lake-level changes and the underestimation of lake water storage was considered due to lake area expansion and lake density. The result demonstrates that GRACE recorded a mass gain (16.43 ± 1.65/11.79 ± 1.25 gt a-1) in the total/inner TP, of which lake storage increase accounts for (8.78 ± 0.75/7.53 ± 0.56 gt a-1) based on ICESat. The northwestern residual may be stored in new lakes and soil moisture as a result of net precipitation gain. According to the character of the lake-level changes, we divide the TP into four subregions. Generally, the changing pattern of lake level concurs with the distribution of precipitation, which is increasing in the inner TP and decreasing in the upstream area of the Indus and Brahmaputra Rivers. An excess of rainfall in the northeastern TP in the summer of 2005 and 2009 caused a simultaneous large increase in water level in many lakes. The correlation of lake changes with precipitation demonstrates that precipitation rather than glacial melt is the main cause of lake-level change in most places. Nonetheless, the meltwater is a considerable supplement for lakes near glaciers such as Selin Co and Nam Co, which partly explains why GRACE indicates a much weaker signal in this region. © The Authors 2016."
"57196420477;8541590300;24281186100;55436296900;24315205000;","Variability and trends of downward surface global solar radiation over the Iberian Peninsula based on ERA-40 reanalysis",2016,"10.1002/joc.4603","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958818725&doi=10.1002%2fjoc.4603&partnerID=40&md5=51a585e6db43f6049583c67888c77fcf","A climate study of the incidence of downward surface global solar radiation (SSRD) in the Iberian Peninsula (IP) based primarily on ERA-40 reanalysis is presented. NCEP/NCAR reanalysis and ground-based records from several Portuguese and Spanish stations have been also considered. The results show that reanalysis can capture a similar inter-annual variability as compared to ground-based observations, especially on a monthly basis, even though annual ERA-40 (NCEP/NCAR) values tend to underestimate (overestimate) the observations with a mean relative difference of around 20 W m–2 (40 W m–2). On the other hand, ground-based measurements in Portuguese stations during the period 1964–1989 show a tendency to decrease until the mid-1970s followed by an increase up to the end of the study period, in line with the dimming/brightening phenomenon reported in the literature. Nevertheless, there are different temporal behaviours as a greater increase since the 1970s is observed in the south and less industrialized regions. Similarly, the ERA-40 reanalysis shows a noticeable decrease until the early 1970s followed by a slight increase up to the end of the 1990s, suggesting a dimming/brightening transition around the early 1970s, earlier in the south and centre and later in the north of the IP. Although there are slight differences in the magnitude of the trends as well as the turning year of the dimming/brightening periods, the decadal changes of ERA-40 fairly agree with the ground-based observations in Portugal and Spain, in contrast to most of the literature for other regions of the world, and is used in the climatology of the SSRD in the study area. NCEP/NCAR reanalysis does not capture the decadal variations of SSRD in the IP. The results show that part of the decadal variability of the global radiation in the IP is related to changes in cloud cover (represented in ERA-40). © 2016 Royal Meteorological Society"
"7005659847;57140160700;7102790108;35568326100;57205842560;7003351429;7006577245;7004607037;7003469326;7005899926;37099534700;57191473265;55192470800;7004177770;57148462400;14066601400;55951906300;7102113229;7101973570;40661065000;6602109913;8387523500;8562497500;7004307916;55053339600;57206604773;36664097800;","Contribution of EARLINET/ACTRIS to the summer 2013 Special Observing Period of the ChArMEx project: monitoring of a Saharan dust event over the western and central Mediterranean",2016,"10.1080/01431161.2016.1222102","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990855929&doi=10.1080%2f01431161.2016.1222102&partnerID=40&md5=e28dd49c10794cafa6f90571f3229536","In the framework of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr/) initiative, a field campaign took place in the western Mediterranean Basin between 10 June and 5 July 2013 within the ADRIMED (Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) project. The scientific objectives of ADRIMED are the characterization of the most common ‘Mediterranean aerosols’ and their direct radiative forcing (column closure and regional scale). During 15–24 June a multi-intrusion dust event took place over the western and central Mediterranean Basin. Extra measurements were carried out by some EARLINET/ACTRIS (European Aerosol Research Lidar Network /Aerosols, Clouds, and Trace gases Research InfraStructure Network, http://www.actris.net/) lidar stations in Spain and Italy, in particular on 22 June in support to the flight over southern Italy of the Falcon 20 aircraft involved in the campaign. This article describes the physical and optical properties of dust observed at the different lidar stations in terms of dust plume centre of mass, optical depth, lidar ratio, and particle depolarization ratio. To link the differences found in the origin of dust plumes, the results are discussed on the basis of back-trajectories and air- and space-borne lidars. This work puts forward the collaboration between a European research infrastructure (ACTRIS) and an international project (ChArMEx) on topics of interest for both parties, and more generally for the atmospheric community. © 2016 Informa UK Limited, trading as Taylor & Francis Group."
"54396796100;57203971602;57190277567;56800262000;56461584100;55738293300;","Arctic sea ice thickness changes in terms of sea ice age",2016,"10.1007/s13131-016-0922-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990829865&doi=10.1007%2fs13131-016-0922-x&partnerID=40&md5=db9c3197352f8c9bda2f01cb21cc3e08","In this study, changes in Arctic sea ice thickness for each ice age category were examined based on satellite observations and modelled results. Interannual changes obtained from Ice, Cloud, and Land Elevation Satellite (ICESat)-based results show a thickness reduction over perennial sea ice (ice that survives at least one melt season with an age of no less than 2 year) up to approximately 0.5–1.0 m and 0.6–0.8 m (depending on ice age) during the investigated winter and autumn ICESat periods, respectively. Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS)-based results provide a view of a continued thickness reduction over the past four decades. Compared to 1980s, there is a clear thickness drop of roughly 0.50 m in 2010s for perennial ice. This overall decrease in sea ice thickness can be in part attributed to the amplified warming climate in north latitudes. Besides, we figure out that strongly anomalous southerly summer surface winds may play an important role in prompting the thickness decline in perennial ice zone through transporting heat deposited in open water (primarily via albedo feedback) in Eurasian sector deep into a broader sea ice regime in central Arctic Ocean. This heat source is responsible for enhanced ice bottom melting, leading to further reduction in ice thickness. © 2016, The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg."
"55867250100;26647582400;35549140200;7202856872;26030013700;6602798575;","Mapping Brazilian savanna vegetation gradients with Landsat time series",2016,"10.1016/j.jag.2016.06.019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84997682850&doi=10.1016%2fj.jag.2016.06.019&partnerID=40&md5=33b06cb36b889d49f34cf331347a1121","Global change has tremendous impacts on savanna systems around the world. Processes related to climate change or agricultural expansion threaten the ecosystem's state, function and the services it provides. A prominent example is the Brazilian Cerrado that has an extent of around 2 million km2 and features high biodiversity with many endemic species. It is characterized by landscape patterns from open grasslands to dense forests, defining a heterogeneous gradient in vegetation structure throughout the biome. While it is undisputed that the Cerrado provides a multitude of valuable ecosystem services, it is exposed to changes, e.g. through large scale land conversions or climatic changes. Monitoring of the Cerrado is thus urgently needed to assess the state of the system as well as to analyze and further understand ecosystem responses and adaptations to ongoing changes. Therefore we explored the potential of dense Landsat time series to derive phenological information for mapping vegetation gradients in the Cerrado. Frequent data gaps, e.g. due to cloud contamination, impose a serious challenge for such time series analyses. We synthetically filled data gaps based on Radial Basis Function convolution filters to derive continuous pixel-wise temporal profiles capable of representing Land Surface Phenology (LSP). Derived phenological parameters revealed differences in the seasonal cycle between the main Cerrado physiognomies and could thus be used to calibrate a Support Vector Classification model to map their spatial distribution. Our results show that it is possible to map the main spatial patterns of the observed physiognomies based on their phenological differences, whereat inaccuracies occurred especially between similar classes and data-scarce areas. The outcome emphasizes the need for remote sensing based time series analyses at fine scales. Mapping heterogeneous ecosystems such as savannas requires spatial detail, as well as the ability to derive important phenological parameters for monitoring habitats or ecosystem responses to climate change. The open Landsat and Sentinel-2 archives provide the satellite data needed for improved analyses of savanna ecosystems globally. © 2016 Elsevier B.V."
"36117406500;7404724327;55500134600;55922085300;55369090600;13905347000;57190378974;55724717800;56457099100;25929874200;55866018700;57190385234;","A comparative study of changes in the Lambert Glacier/Amery Ice Shelf system, East Antarctica, during 2004-2008 using gravity and surface elevation observations",2016,"10.1017/jog.2016.76","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994618650&doi=10.1017%2fjog.2016.76&partnerID=40&md5=efcefcaed13c0662c77927463f878221","We present results of a regional comparative study of surface mass changes from 2004 to 2008 based on Gravity Recovery and Climate Experiment (GRACE), The Ice, Cloud and Land Elevation Satellite (ICESat) and CHINARE observations over the Lambert Glacier/Amery Ice Shelf system (LAS). Estimation of the ICESat mass change rates benefitted from the density measurements along the CHINARE traverse and a spatial density adjustment method for reducing the effect of spatial density variations. In the high-elevation inland region, a positive trend was estimated from both ICESat and GRACE data, which is in line with the CHINARE accumulation measurements. In the coastal region, there were areas with high level accumulations in both ICESat and GRACE trend maps. In many high flow-speed glacier areas, negative mass change rates may be caused by dynamic ice flow discharges that have surpassed the snow accumulation. Overall, the mass change rate estimate in the LAS of 2004-2008 from the GRACE, ICESat and CHINARE data is 5.41 ± 4.59 Gt a-1, indicating a balanced to slightly positive mass trend. Along with other published results, this suggests that a longerterm positive mass trend in the LAS may have slowed in recent years. © The Author(s) 2016."
"35248168500;56265819100;54937875200;6507467563;6701672112;","A model-based examination of multivariate physical modes in the Gulf of Alaska",2016,"10.1016/j.dsr2.2016.04.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992312382&doi=10.1016%2fj.dsr2.2016.04.005&partnerID=40&md5=c76cf140f5a5206677cba0ffce5e30d0","We use multivariate output from a hydrodynamic model of the Gulf of Alaska (GOA) to explore the covariance among its physical state and air/sea fluxes. We attempt to summarize this coupled variability using a limited set of patterns, and examine their correlation to three large-scale climate indices relevant to the Northeast Pacific. This analysis is focused on perturbations from monthly climatology of the following attributes of the GOA: sea surface temperature, sea surface height, mixed layer depth, sea surface salinity, latent heat flux, sensible heat flux, shortwave irradiance, net long wave irradiance, currents at 40 m depth, and wind stress. We identified two multivariate modes, both substantially correlated with the Pacific Decadal Oscillation (PDO) and Multivariate El Nino (MEI) indices on interannual timescales, which together account for ~30% of the total normalized variance of the perturbation time series. These two modes indicate the following covarying events during periods of positive PDO/MEI: (1) anomalously warm, wet and windy conditions (typically in winter), with elevated coastal SSH, followed 2–5 months later by (2) reduced cloud cover, with emerging shelf-break eddies. Similar modes are found when the analysis is performed separately on the eastern and western GOA; in general, modal amplitudes appear stronger in the western GOA. © 2016 Elsevier Ltd"
"57040141000;7408519295;26324818700;","Contrasting the eastern Pacific El Niño and the central Pacific El Niño: process-based feedback attribution",2016,"10.1007/s00382-015-2971-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84953397694&doi=10.1007%2fs00382-015-2971-9&partnerID=40&md5=580c83594d4f687306eb9b332ac00b19","This paper examines the roles of radiative and non-radiative air–sea coupled thermodynamic processes in modifying sea surface temperature (SST) anomalies driven by (air–sea coupled) oceanic dynamic processes, focusing on their contributions to the key differences between the eastern Pacific (EP) El Niño and the central Pacific (CP) El Niño. The attribution is achieved by decomposing SST anomalies into partial temperature anomalies due to individual processes using a coupled atmosphere-surface climate feedback-response analysis method. Oceanic processes induce warming from the central to the eastern equatorial Pacific and cooling over the western basin with a maximum warming center in the central Pacific for both types of El Niño. The processes that act to oppose the oceanic process-induced SST anomalies are surface latent heat flux, sensible heat flux, cloud, and atmospheric dynamic feedbacks, referred to as negative-feedback processes. The cooling due to each of the four negative-feedback processes is the strongest in the region where the initial warming due to oceanic processes is the largest. Water–vapor feedback is the sole process that acts to enhance the initial warming induced by oceanic processes. The increase in atmospheric water vapor over the eastern Pacific is much stronger for the EP El Niño than for the CP El Niño. It is the strong water–vapor feedback over the eastern Pacific and the strong negative feedbacks over the central equatorial Pacific that help to relocate the maximum warming center from the central Pacific to the eastern basin for the EP El Niño. © 2016, The Author(s)."
"57194333867;6603837254;","Urban heat islands as viewed by microwave radiometers and thermal time indices",2016,"10.3390/rs8100831","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010697395&doi=10.3390%2frs8100831&partnerID=40&md5=e9bfd405c50d670de7a562404155c831","Urban heat islands (UHIs) have been long studied using both ground-based observations of air temperature and remotely sensed thermal infrared (TIR) data. While ground-based observations lack spatial detail even in the occasional ""dense"" urban network, skin temperature retrievals using TIR data have lower temporal coverage due to revisit frequency, limited swath width, and cloud cover. Algorithms have recently been developed to retrieve near-surface air temperatures using microwave radiometer data, which enables characterization of UHIs in metropolitan areas, major conurbations, and global megacities at regional to continental scales using temporally denser time series than those that have been available from TIR sensors. Here we examine how UHIs appear across the entire Western Hemisphere using surface air temperatures derived from the Advanced Microwave Scanning Radiometers (AMSRs), AMSR-E onboard the National Aeronautics and Space Administration's (NASA's) Aqua and AMSR2 onboard the Japan Aerospace eXploration Agency's Global Change Observation Mission-Water1 (JAXA's GCOM-W1) satellites. We compare these data with station observations from the Global Historical Climate Network (GHCN) for 27 major cities across North America (in 83 urban-rural groupings) to demonstrate the capability of microwave data in a UHI study. Two measures of thermal time, accumulated diurnal and nocturnal degree-days, are calculated from the remotely sensed surface air temperature time series to characterize the urban-rural thermal differences over multiple growing seasons. Daytime urban thermal accumulations from the microwave data were sometimes lower than in adjacent rural areas. In contrast, station observations showed consistently higher day and night thermal accumulations in cities. UHIs are more pronounced at night, with 55% (AMSRs) and 93% (GHCN) of urban-rural groupings showing higher accumulated nocturnal degree-days in cities. While urban-rural thermal gradients may vary according to different datasets or locations, day-night differences in thermal time metrics were consistently lower (> 90% of urban-rural groupings) in urban areas than in rural areas for both datasets. We propose that the normalized difference accumulated thermal time index (NDATTI) is a more robust metric for comparative UHI studies than simple temperature differences because it can be calculated from either station or remotely sensed data and it attenuates latitudinal effects. © 2016 by the authors."
"35932420900;11939918300;55805082800;26649925100;","Intensification of convective extremes driven by cloud-cloud interaction",2016,"10.1038/ngeo2789","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989876826&doi=10.1038%2fngeo2789&partnerID=40&md5=a7b5e6ee94afd976779b9071067e1dc2","In a changing climate, a key role may be played by the response of convective-type cloud and precipitation to temperature changes. Yet, it is unclear if convective precipitation intensities will increase mainly due to thermodynamic or dynamical processes. Here we perform large eddy simulations of convection by imposing a realistic diurnal cycle of surface temperature. We find convective events to gradually self-organize into larger cloud clusters and those events occurring late in the day to produce the highest precipitation intensities. Tracking rain cells throughout their life cycles, we show that events which result from collisions respond strongly to changes in boundary conditions, such as temperature changes. Conversely, events not resulting from collisions remain largely unaffected by the boundary conditions. Increased surface temperature indeed leads to more interaction between events and stronger precipitation extremes. However, comparable intensification occurs when leaving temperature unchanged but simply granting more time for self-organization. These findings imply that the convective field as a whole acquires a memory of past precipitation and inter-cloud dynamics, driving extremes. For global climate model projections, our results suggest that the interaction between convective clouds must be incorporated to simulate convective extremes and the diurnal cycle more realistically. © 2016 Macmillan Publishers Limited, part of Springer Nature."
"35098748100;24597634900;8680433600;35330367300;6602350870;7102591209;55791137300;36722732500;","Investigation of ice particle habits to be used for ice cloud remote sensing for the GCOM-C satellite mission",2016,"10.5194/acp-16-12287-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989336852&doi=10.5194%2facp-16-12287-2016&partnerID=40&md5=b962fa6168bc2b4d88e9ce65e623d8f5","In this study, various ice particle habits are investigated in conjunction with inferring the optical properties of ice clouds for use in the Global Change Observation Mission-Climate (GCOM-C) satellite programme. We develop a database of the single-scattering properties of five ice habit models: plates, columns, droxtals, bullet rosettes, and Voronoi. The database is based on the specification of the Second Generation Global Imager (SGLI) sensor on board the GCOM-C satellite, which is scheduled to be launched in 2017 by the Japan Aerospace Exploration Agency. A combination of the finite-difference time-domain method, the geometric optics integral equation technique, and the geometric optics method is applied to compute the single-scattering properties of the selected ice particle habits at 36 wavelengths, from the visible to the infrared spectral regions. This covers the SGLI channels for the size parameter, which is defined as a single-particle radius of an equivalent volume sphere, ranging between 6 and 9000ĝ€μm. The database includes the extinction efficiency, absorption efficiency, average geometrical cross section, single-scattering albedo, asymmetry factor, size parameter of a volume-equivalent sphere, maximum distance from the centre of mass, particle volume, and six nonzero elements of the scattering phase matrix. The characteristics of calculated extinction efficiency, single-scattering albedo, and asymmetry factor of the five ice particle habits are compared. Furthermore, size-integrated bulk scattering properties for the five ice particle habit models are calculated from the single-scattering database and microphysical data. Using the five ice particle habit models, the optical thickness and spherical albedo of ice clouds are retrieved from the Polarization and Directionality of the Earth's Reflectances-3 (POLDER-3) measurements, recorded on board the Polarization and Anisotropy of Reflectances for Atmospheric Sciences coupled with Observations from a Lidar (PARASOL) satellite. The optimal ice particle habit for retrieving the SGLI ice cloud properties is investigated by adopting the spherical albedo difference (SAD) method. It is found that the SAD is distributed stably due to the scattering angle increases for bullet rosettes with an effective diameter (<i>D</i>eff) of 10ĝ€μm and Voronoi particles with <i>D</i>eff values of 10, 60, and 100ĝ€μm. It is confirmed that the SAD of small bullet-rosette particles and all sizes of Voronoi particles has a low angular dependence, indicating that a combination of the bullet-rosette and Voronoi models is sufficient for retrieval of the ice cloud's spherical albedo and optical thickness as effective habit models for the SGLI sensor. Finally, SAD analysis based on the Voronoi habit model with moderate particle size (<i>D</i>eff Combining double low line 60ĝ€μm) is compared with the conventional general habit mixture model, inhomogeneous hexagonal monocrystal model, five-plate aggregate model, and ensemble ice particle model. The Voronoi habit model is found to have an effect similar to that found in some conventional models for the retrieval of ice cloud properties from space-borne radiometric observations. © Author(s) 2016. CC Attribution 3.0 License."
"40461229800;7006029393;56828858800;6603547710;22980282700;7202902739;57191416507;","Colorado air quality impacted by long-range-transported aerosol: A set of case studies during the 2015 Pacific Northwest fires",2016,"10.5194/acp-16-12329-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989925722&doi=10.5194%2facp-16-12329-2016&partnerID=40&md5=18229efbe37e3f85aff715eefb7413d5","Biomass burning plumes containing aerosols from forest fires can be transported long distances, which can ultimately impact climate and air quality in regions far from the source. Interestingly, these fires can inject aerosols other than smoke into the atmosphere, which very few studies have evidenced. Here, we demonstrate a set of case studies of long-range transport of mineral dust aerosols in addition to smoke from numerous fires (including predominantly forest fires and a few grass/shrub fires) in the Pacific Northwest to Colorado, US. These aerosols were detected in Boulder, Colorado, along the Front Range using beta-ray attenuation and energy-dispersive X-ray fluorescence spectroscopy, and corroborated with satellite-borne lidar observations of smoke and dust. Further, we examined the transport pathways of these aerosols using air mass trajectory analysis and regional-and synoptic-scale meteorological dynamics. Three separate events with poor air quality and increased mass concentrations of metals from biomass burning (S and K) and minerals (Al, Si, Ca, Fe, and Ti) occurred due to the introduction of smoke and dust from regional-and synoptic-scale winds. Cleaner time periods with good air quality and lesser concentrations of biomass burning and mineral metals between the haze events were due to the advection of smoke and dust away from the region. Dust and smoke present in biomass burning haze can have diverse impacts on visibility, health, cloud formation, and surface radiation. Thus, it is important to understand how aerosol populations can be influenced by long-range-transported aerosols, particularly those emitted from large source contributors such as wildfires. © 2016 Author(s)."
"56005080300;23082420800;7201572530;7004060399;7006248174;","New observational evidence for a positive cloud feedback that amplifies the Atlantic Multidecadal Oscillation",2016,"10.1002/2016GL069961","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987936751&doi=10.1002%2f2016GL069961&partnerID=40&md5=689e78ff63b505fc42927354244fd847","The Atlantic Multidecadal Oscillation (AMO) affects climate variability in the North Atlantic basin and adjacent continents with potential societal impacts. Previous studies based on model simulations and short-term satellite retrievals hypothesized an important role for cloud radiative forcing in modulating the persistence of the AMO in the tropics, but this mechanism remains to be tested with long-term observational records. Here we analyze data sets that span multiple decades and present new observational evidence for a positive feedback between total cloud amount, sea surface temperature (SST), and atmospheric circulation that can strengthen the persistence and amplitude of the tropical branch of the AMO. In addition, we estimate cloud amount feedback from observations and quantify its impact on SST with idealized modeling experiments. From these experiments we conclude that cloud feedbacks can account for 10% to 31% of the observed SST anomalies associated with the AMO over the tropics. ©2016. American Geophysical Union. All Rights Reserved."
"55683113200;7006960329;35422938600;55683310400;35423527600;7005773698;","Phytoplankton blooms weakly influence the cloud forming ability of sea spray aerosol",2016,"10.1002/2016GL069922","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992360126&doi=10.1002%2f2016GL069922&partnerID=40&md5=4545fdd1303713d0ea27370be9818132","After many field studies, the establishment of connections between marine microbiological processes, sea spray aerosol (SSA) composition, and cloud condensation nuclei (CCN) has remained an elusive challenge. In this study, we induced algae blooms to probe how complex changes in seawater composition impact the ability of nascent SSA to act as CCN, quantified by using the apparent hygroscopicity parameter (κapp). Throughout all blooms, κapp ranged between 0.7 and 1.4 (average 0.95 ± 0.15), consistent with laboratory investigations using algae-produced organic matter, but differing from climate model parameterizations and in situ SSA generation studies. The size distribution of nascent SSA dictates that changes in κapp associated with biological processing induce less than 3% change in expected CCN concentrations for typical marine cloud supersaturations. The insignificant effect of hygroscopicity on CCN concentrations suggests that the SSA production flux and/or secondary aerosol chemistry may be more important factors linking ocean biogeochemistry and marine clouds. ©2016. American Geophysical Union. All Rights Reserved."
"55569698000;7004807312;15071907100;","Dependence of global radiative feedbacks on evolving patterns of surface heat fluxes",2016,"10.1002/2016GL070907","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989318904&doi=10.1002%2f2016GL070907&partnerID=40&md5=754a8f20ceac0d180b1c16fdabdf0769","In most climate models, after an abrupt increase in radiative forcing the climate feedback parameter magnitude decreases with time. We demonstrate how the evolution of the pattern of ocean heat uptake—moving from a more homogeneous toward a heterogeneous and high-latitude-enhanced pattern—influences not only regional but also global climate feedbacks. We force a slab ocean model with scaled patterns of ocean heat uptake derived from a coupled ocean-atmosphere general circulation model. Steady state results from the slab ocean approximate transient results from the dynamic ocean configuration. Our results indicate that cloud radiative effects play an important role in decreasing the magnitude of the climate feedback parameter. The ocean strongly affects atmospheric temperatures through both heat uptake and through influencing atmospheric feedbacks. This highlights the challenges associated with reliably predicting transient or equilibrated climate system states from shorter-term climate simulations and observed climate variability. ©2016. American Geophysical Union. All Rights Reserved."
"7006145109;15834571900;","Observing the response of the land surface to climate variability by time series analysis of satellite observations",2016,"10.11834/jrs.20166223","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992388744&doi=10.11834%2fjrs.20166223&partnerID=40&md5=c3ea76cfcd24a2af8e12334d3f6bac14","Satellite observations of the terrestrial biosphere cover a period of time sufficiently extended to allow the calculation of a reliable climatology. The latter is particularly relevant for studies of vegetation response to climate variability. Observations from space of the land surface are hampered by clouds at shorter wavelength and affected by water in the atmosphere in the microwave range. Both polar orbiting and geostationary satellites have a revisit frequency high enough to allow for some redundancy relative to the processes being observed, so that time series where a fraction of observations are removed and the resulting gaps filled are still very useful to monitor land surface processes. We applied the Harmonic ANalysis of Time Series (HANTS) to identify and remove anomalous observations (outliers) and to fill the resulting gaps. The HANTS algorithm has been widely used to reconstruct time series of Normalized Difference Vegetation Index (NDVI), Leaf Area Index (LAI), Land Surface Temperature (LST) as well as the Polarization Difference Brightness Temperature (PDBT) during the past 30 years to remove random noise or eliminate cloud/snow contamination. Several studies in North and Southern Africa, South America, Europe, China and India captured the response of the land surface to climate forcing, modulated by water availability across a range of temporal scales from hourly to decennial. These studies are reviewed to illustrate how the analysis of time series of different land surface properties reveal processes and interactions. © 2016, Science Press. All right reserved."
"7006622255;24490844700;7006550959;7102096431;6701313416;55919261400;","PLASIM-GENIE v1.0: A new intermediate complexity AOGCM",2016,"10.5194/gmd-9-3347-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988735470&doi=10.5194%2fgmd-9-3347-2016&partnerID=40&md5=4e2b0e35b24d5295e6b619e0c8cfff71","We describe the development, tuning and climate of Planet Simulator (PLASIM)-Grid-ENabled Integrated Earth system model (GENIE), a new intermediate complexity Atmosphere-Ocean General Circulation Model (AOGCM), built by coupling the Planet Simulator to the ocean, sea-ice and land-surface components of the GENIE Earth system model. PLASIM-GENIE supersedes GENIE-2, a coupling of GENIE to the Reading Intermediate General Circulation Model (IGCM). The primitive-equation atmosphere includes chaotic, three-dimensional (3-D) motion and interactive radiation and clouds, and dominates the computational load compared to the relatively simpler frictionalgeostrophic ocean, which neglects momentum advection. The model is most appropriate for long-timescale or large ensemble studies where numerical efficiency is prioritised, but lack of data necessitates an internally consistent, coupled calculation of both oceanic and atmospheric fields. A 1000-year simulation with PLASIM-GENIE requires approximately 2 weeks on a single node of a 2.1 GHz AMD 6172 CPU. We demonstrate the tractability of PLASIM-GENIE ensembles by deriving a subjective tuning of the model with a 50-member ensemble of 1000-year simulations. The simulated climate is presented considering (i) global fields of seasonal surface air temperature, precipitation, wind, solar and thermal radiation, with comparisons to reanalysis data; (ii) vegetation carbon, soil moisture and aridity index; and (iii) sea surface temperature, salinity and ocean circulation. Considering its resolution, PLASIM-GENIE reproduces the main features of the climate system well and demonstrates usefulness for a wide range of applications. © 2016 Author(s)."
"26645289600;55332348600;7402064802;","Insights from a refined decomposition of cloud feedbacks",2016,"10.1002/2016GL069917","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987605289&doi=10.1002%2f2016GL069917&partnerID=40&md5=f49d6dd9a4d8dca6636ea0124b51cb8b","Decomposing cloud feedback into components due to changes in several gross cloud properties provides valuable insights into its physical causes. Here we present a refined decomposition that separately considers changes in free tropospheric and low cloud properties, better connecting feedbacks to individual governing processes and avoiding ambiguities present in a commonly used decomposition. It reveals that three net cloud feedback components are robustly nonzero: positive feedbacks from increasing free tropospheric cloud altitude and decreasing low cloud cover and a negative feedback from increasing low cloud optical depth. Low cloud amount feedback is the dominant contributor to spread in net cloud feedback but its anticorrelation with other components damps overall spread. The ensemble mean free tropospheric cloud altitude feedback is roughly 60% as large as the standard cloud altitude feedback because it avoids aliasing in low cloud reductions. Implications for the “null hypothesis” climate sensitivity from well-understood and robustly simulated feedbacks are discussed. ©2016. American Geophysical Union. All Rights Reserved."
"55663852700;56455276600;8261329600;55635715000;55682762000;7102634471;6602252175;7006497590;6701859178;","Investigation of a potential HCHO measurement artifact from ISOPOOH",2016,"10.5194/amt-9-4561-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988584728&doi=10.5194%2famt-9-4561-2016&partnerID=40&md5=986214a0c3069d5482dcd8ddb8eff340","Recent laboratory experiments have shown that a first generation isoprene oxidation product, ISOPOOH, can decompose to methyl vinyl ketone (MVK) and methacrolein (MACR) on instrument surfaces, leading to overestimates of MVK and MACR concentrations. Formaldehyde (HCHO) was suggested as a decomposition co-product, raising concern that in situ HCHO measurements may also be affected by an ISOPOOH interference. The HCHO measurement artifact from ISOPOOH for the NASA In Situ Airborne Formaldehyde instrument (ISAF) was investigated for the two major ISOPOOH isomers, (1,2)-ISOPOOH and (4,3)-ISOPOOH, under dry and humid conditions. The dry conversion of ISOPOOH to HCHO was 3 ± 2 % and 6 ± 4 % for (1,2)-ISOPOOH and (4,3)-ISOPOOH, respectively. Under humid (relative humidity of 40-60 %) conditions, conversion to HCHO was 6 ± 4 % for (1,2)-ISOPOOH and 10 ± 5 % for (4,3)-ISOPOOH. The measurement artifact caused by conversion of ISOPOOH to HCHO in the ISAF instrument was estimated for data obtained on the 6 September 2013 flight of the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign. Prompt ISOPOOH conversion to HCHO was the source of &lt; 4 % of the observed HCHO, including in the high-isoprene boundary layer. Time-delayed conversion, where previous exposure to ISOPOOH affects measured HCHO later in the flight, was conservatively estimated to be &lt; 10 % of observed HCHO, and is significant only when high ISOPOOH sampling periods immediately precede periods of low HCHO. © Author(s) 2016."
"56206456800;57191221599;8383395800;6504688501;57191980050;9736951600;7004402705;35547807400;7005211669;","Atmospheric lifetimes, infrared absorption spectra, radiative forcings and global warming potentials of NF3 and CF3CF2Cl (CFC-115)",2016,"10.5194/acp-16-11451-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988354966&doi=10.5194%2facp-16-11451-2016&partnerID=40&md5=9f1fcd3ad0947db4c1a2dd83e97279f3","Fluorinated compounds such as NF3 and C2F5Cl (CFC-115) are characterised by very large global warming potentials (GWPs), which result from extremely long atmospheric lifetimes and strong infrared absorptions in the atmospheric window. In this study we have experimentally determined the infrared absorption cross sections of NF3 and CFC-115, calculated the radiative forcing and efficiency using two radiative transfer models and identified the effect of clouds and stratospheric adjustment. The infrared cross sections are within 10% of previous measurements for CFC-115 but are found to be somewhat larger than previous estimates for NF3, leading to a radiative efficiency for NF3 that is 25% larger than that quoted in the Intergovernmental Panel on Climate Change Fifth Assessment Report. A whole atmosphere chemistry-climate model was used to determine the atmospheric lifetimes of NF3 and CFC-115 to be (509±21) years and (492±22) years, respectively. The GWPs for NF3 are estimated to be 15 600, 19 700 and 19 700 over 20, 100 and 500 years, respectively. Similarly, the GWPs for CFC-115 are 6030, 7570 and 7480 over 20, 100 and 500 years, respectively. © 2016 Author(s)."
"26634244600;14035836100;7003591311;","A long-term study of aerosol-cloud interactions and their radiative effect at the Southern Great Plains using ground-based measurements",2016,"10.5194/acp-16-11301-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987762581&doi=10.5194%2facp-16-11301-2016&partnerID=40&md5=2a4e9c4cd65b9b6061d52f52e3a85564","Empirical estimates of the microphysical response of cloud droplet size distribution to aerosol perturbations are commonly used to constrain aerosol-cloud interactions in climate models. Instead of empirical microphysical estimates, here macroscopic variables are analyzed to address the influence of aerosol particles and meteorological descriptors on instantaneous cloud albedo and the radiative effect of shallow liquid water clouds. Long-term ground-based measurements from the Atmospheric Radiation Measurement (ARM) program over the Southern Great Plains are used. A broad statistical analysis was performed on 14 years of coincident measurements of low clouds, aerosol, and meteorological properties. Two cases representing conflicting results regarding the relationship between the aerosol and the cloud radiative effect were selected and studied in greater detail. Microphysical estimates are shown to be very uncertain and to depend strongly on the methodology, retrieval technique and averaging scale. For this continental site, the results indicate that the influence of the aerosol on the shallow cloud radiative effect and albedo is weak and that macroscopic cloud properties and dynamics play a much larger role in determining the instantaneous cloud radiative effect compared to microphysical effects. On a daily basis, aerosol shows no correlation with cloud radiative properties (correlation D =-0.01±0.03), whereas the liquid water path shows a clear signal (correlation D =-0.56± .02). © 2016 Author(s)."
"36462180600;6602182223;57191077391;49861577800;26221198200;55173596300;7102054073;57208121852;","Community Intercomparison Suite (CIS) v1.4.0: A tool for intercomparing models and observations",2016,"10.5194/gmd-9-3093-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84986327420&doi=10.5194%2fgmd-9-3093-2016&partnerID=40&md5=e26df0727203a6bbde928c7f294d6849","The Community Intercomparison Suite (CIS) is an easy-to-use command-line tool which has been developed to allow the straightforward intercomparison of remote sensing, in situ and model data. While there are a number of tools available for working with climate model data, the large diversity of sources (and formats) of remote sensing and in situ measurements necessitated a novel software solution. Developed by a professional software company, CIS supports a large number of gridded and ungridded data sources ""out-of-the-box"", including climate model output in NetCDF or the UK Met Office pp file format, CloudSat, CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization), MODIS (MODerate resolution Imaging Spectroradiometer), Cloud and Aerosol CCI (Climate Change Initiative) level 2 satellite data and a number of in situ aircraft and ground station data sets. The open-source architecture also supports user-defined plugins to allow many other sources to be easily added. Many of the key operations required when comparing heterogenous data sets are provided by CIS, including subsetting, aggregating, collocating and plotting the data. Output data are written to CF-compliant NetCDF files to ensure interoperability with other tools and systems. The latest documentation, including a user manual and installation instructions, can be found on our website (http://cistools.net). Here, we describe the need which this tool fulfils, followed by descriptions of its main functionality (as at version 1.4.0) and plugin architecture which make it unique in the field. © 2016 The Author(s)."
"57190072737;35423527600;57191076209;26434854300;26639062900;","Lake spray aerosol generation: A method for producing representative particles from freshwater wave breaking",2016,"10.5194/amt-9-4311-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84986268712&doi=10.5194%2famt-9-4311-2016&partnerID=40&md5=08f386176c05f41c351ea40e5a9f8ec6","Wave-breaking action in bodies of freshwater produces atmospheric aerosols via a similar mechanism to sea spray aerosol (SSA) from seawater. The term lake spray aerosol (LSA) is proposed to describe particles formed by this mechanism, which have been observed over the Laurentian Great Lakes. Though LSA has been identified from size distribution measurements during a single measurement campaign, no measurements of LSA composition or relationship to bubble-bursting dynamics have been conducted. An LSA generator utilizing a plunging jet, similar to many SSA generators, was constructed for the generation of aerosol from freshwater samples and model salt solutions. To evaluate this new generator, bubble and aerosol number size distributions were measured for salt solutions representative of freshwater (CaCO3) and seawater (NaCl) at concentrations ranging from that of freshwater to seawater (0.05-35g kg-1), synthetic seawater (inorganic), synthetic freshwater (inorganic), and a freshwater sample from Lake Michigan. Following validation of the bubble and aerosol size distributions using synthetic seawater, a range of salt concentrations were investigated. The systematic studies of the model salts, synthetic freshwater, and Lake Michigan sample indicate that LSA is characterized by a larger number size distribution mode diameter of 300nm (lognormal), compared to seawater at 110nm. Decreasing salt concentrations from seawater to freshwater led to greater bubble coalescence and formation of larger bubbles, which generated larger particles and lower aerosol number concentrations. This resulted in a bimodal number size distribution with a primary mode (180±20nm) larger than that of SSA, as well as a secondary mode (46±6nm) smaller than that of SSA. This new method for studying LSA under isolated conditions is needed as models, at present, utilize SSA parameterizations for freshwater systems, which do not accurately predict the different size distributions observed for LSA or resulting climate properties. Given the abundance of freshwater globally, this potentially important source of aerosol needs to be thoroughly characterized, as the sizes produced are relevant to light scattering, cloud condensation nuclei (CCN), and ice nuclei (IN) concentrations over bodies of freshwater. © Author(s) 2016."
"57190277161;36171703500;8715232900;57208121852;","Inverse modelling of Köhler theory - Part 1: A response surface analysis of CCN spectra with respect to surface-active organic species",2016,"10.5194/acp-16-10941-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84986252232&doi=10.5194%2facp-16-10941-2016&partnerID=40&md5=b4fc527dcc48e5daf9819f08d36a142f","In this study a novel framework for inverse modelling of cloud condensation nuclei (CCN) spectra is developed using Köhler theory. The framework is established by using model-generated synthetic measurements as calibration data for a parametric sensitivity analysis. Assessment of the relative importance of aerosol physicochemical parameters, while accounting for bulk-surface partitioning of surface-active organic species, is carried out over a range of atmospherically relevant supersaturations. By introducing an objective function that provides a scalar metric for diagnosing the deviation of modelled CCN concentrations from synthetic observations, objective function response surfaces are presented as a function of model input parameters. Crucially, for the chosen calibration data, aerosol-CCN spectrum closure is confirmed as a well-posed inverse modelling exercise for a subset of the parameters explored herein. The response surface analysis indicates that the appointment of appropriate calibration data is particularly important. To perform an inverse aerosol-CCN closure analysis and constrain parametric uncertainties, it is shown that a high-resolution CCN spectrum definition of the calibration data is required where single-valued definitions may be expected to fail. Using Köhler theory to model CCN concentrations requires knowledge of many physicochemical parameters, some of which are difficult to measure in situ on the scale of interest and introduce a considerable amount of parametric uncertainty to model predictions. For all partitioning schemes and environments modelled, model output showed significant sensitivity to perturbations in aerosol log-normal parameters describing the accumulation mode, surface tension, organic:inorganic mass ratio, insoluble fraction, and solution ideality. Many response surfaces pertaining to these parameters contain well-defined minima and are therefore good candidates for calibration using a Monte Carlo Markov Chain (MCMC) approach to constraining parametric uncertainties. A complete treatment of bulk-surface partitioning is shown to predict CCN spectra similar to those calculated using classical Köhler theory with the surface tension of a pure water drop, as found in previous studies. In addition, model sensitivity to perturbations in the partitioning parameters was found to be negligible. As a result, this study supports previously held recommendations that complex surfactant effects might be neglected, and the continued use of classical Köhler theory in global climate models (GCMs) is recommended to avoid an additional computational burden. The framework developed is suitable for application to many additional composition-dependent processes that might impact CCN activation potential. However, the focus of this study is to demonstrate the efficacy of the applied sensitivity analysis to identify important parameters in those processes and will be extended to facilitate a global sensitivity analysis and inverse aerosol-CCN closure analysis. © Author(s) 2016."
"55656493400;55430046100;57218273453;","Effects of the coupling process on shortwave radiative feedback during ENSO in FGOALS-g",2016,"10.1080/16742834.2016.1192454","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056183407&doi=10.1080%2f16742834.2016.1192454&partnerID=40&md5=989323f6883ca07678810c2c29eae8f6","Satisfactory simulation of negative shortwave (SW) radiative feedback during ENSO in the equatorial Pacific remains a challenging issue for climate models. Previous studies have focused on specific physical processes in the atmospheric and/or oceanic model, but the coupling process in coupled models has not received much attention. To investigate the coupling effect on SW feedback, two versions of an AGCM and their corresponding coupled models are analyzed. Results indicate that the effects of the coupling process in the two versions lead to weakening and enhancement of the negative feedback in the earlier and new versions, respectively, mainly due to their different changes in cloud fraction feedback and dynamical feedback. Further examination of the nonlinearity of the feedback reveals that the opposite coupling effects in the two versions originate from their different responses to El Niño and to La Niña. © 2016, © 2016 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group."
"56906670400;7102054679;38362738700;57202407121;","Evaluation of the surface heat budget over the tropical Indian Ocean in two versions of FGOALS",2016,"10.1080/16742834.2016.1199945","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075755332&doi=10.1080%2f16742834.2016.1199945&partnerID=40&md5=4d3a4163a6b1b764135971e1abc9adce","Changes of the net ocean surface heat flux (Qnet) into the tropical Indian Ocean (TIO) may be an indicator of the climate changes in the Asia and Indian–Pacific Ocean regions with the steadily warming trend in the TIO since the 1950s. Using two observational ocean surface flux products, this letter evaluates the historical simulations of Qnet over the TIO during 1984–2005 in two versions of FGOALS, from CMIP5. The results show that both models present a basin-wide underestimation of net surface heat flux, possibly resulting from the positive latent heat flux biases extending over almost the entire TIO basin. Both models share an Indian Ocean dipole-like bias in the net surface heat flux, consistent with precipitation, SST, and subsurface ocean temperature biases, which can be traced to errors in the South Asian summer monsoon. Area-averaged annual time series analyses of the surface heat budget imply that the FGOALS-s2 bias lies more in radiative imbalance, illustrating the need to improve cloud simulation; while the FGOALS-g2 bias presents ocean surface turbulence flux as the key process, requiring improvement in the simulation of oceanic processes. Neither FGOALS-g2 nor FGOALS-s2 can capture the decreasing tendency of Qnet well. All observed and simulated datasets imply surface latent heat flux as the primary contributing component, indicating the simulation biases of models may derive mainly from the biases in simulating latent heat flux. A small latent heat flux increase in models can be considered to be slowed by relaxed wind, increased stability, and surface relative humidity. © 2016, © 2016 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group."
"57196171548;12040335900;36015299300;57216619452;","Influence of altered low cloud parameterizations for seasonal variation of Arctic cloud amount on climate feedbacks",2016,"10.1007/s00382-015-2926-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949568449&doi=10.1007%2fs00382-015-2926-1&partnerID=40&md5=558280a94fb2414dabbdf7644b13d6c0","This study investigates the alteration of climate feedbacks due to overestimated wintertime low-level cloud amount bias over the Arctic region (60°N–90°N) in a climate model. The climate feedback was quantitatively examined through radiative kernels that are pre-calculated radiative responses of climate variables to doubling of carbon dioxide concentration in NCAR Community Atmosphere Model version 3 (CAM3). Climate models have various annual cycle of the Arctic cloud amount at the low-level particularly with large uncertainty in winter and CAM3 may tend to overestimate the Arctic low-level cloud. In this study, the seasonal variation of low-level cloud amount was modified by reducing the wintertime cloud amount by up to 35 %, and then compared with the original without seasonal variation. Thus, we investigate how that bias may affect climate feedbacks and the projections of future Arctic warming. The results show that the decrease in low-level cloud amount slightly affected the radiation budgets because of a small amount of incident solar insolation in winter, but considerably changed water vapor and temperature profiles. Consequently, the most distinctive was decreases in water vapor feedback and contribution of heat transport (by −0.20 and −0.55 W m−2 K−1, respectively) and increases in the lapse rate feedback and cloud feedback (by 0.13 and 0.58 W m−2 K−1, respectively) during winter in this model experiment. This study suggests that the change in Arctic cloud amount effectively reforms the contributions of individual climate feedbacks to Arctic climate system and leads to opposing effects on different feedbacks, which cancel out in the model. © 2015, Springer-Verlag Berlin Heidelberg."
"55940978200;","Diurnal timescale feedbacks in the tropical cumulus regime",2016,"10.1002/2016MS000713","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990041458&doi=10.1002%2f2016MS000713&partnerID=40&md5=588067463d8c14a7931f17eb7b57547c","Although the importance of the diurnal cycle in modulating clouds and precipitation has long been recognized, its impact on the climate system at longer timescales has remained elusive. Mounting evidence indicates that the diurnal cycle may substantially affect leading climate modes through nonlinear rectification. In this study, an idealized cloud-resolving model experiment is executed to isolate a diurnal timescale feedback in the shallow cumulus regime over the tropical warm pool. This feedback is isolated by modifying the period of the diurnal cycle (or removing it), which proportionally scales (or removes) the diurnal thermodynamic forcing that clouds respond to. This diurnal forcing is identified as covarying cycles of static stability and humidity in the lower troposphere, wherein the most unstable conditions coincide with greatest humidity each afternoon. This diurnal forcing yields deeper clouds and greater daily-mean cumulus heating than would otherwise occur, in turn reducing large-scale subsidence from day to day according to the “weak temperature gradient” approximation. This diurnal forcing therefore manifests as a timescale feedback by accelerating the onset of deep convection. The longwave cloud-radiation effect is found to amplify this timescale feedback, since the resulting invigoration of clouds (increased upper-cloud radiative cooling, with suppressed cooling below) scales with cloud depth (i.e., optical thickness), and hence with the magnitude of diurnal forcing. These findings highlight the pressing need to remedy longstanding problems related to the diurnal cycle in many climate models. Given the evident sensitivity of climate variability to diurnal processes, doing so may yield advances in climate prediction at longer timescales. © 2016. The Authors."
"55437450100;7201504886;8696069500;6603247427;","Radiative convective equilibrium as a framework for studying the interaction between convection and its large-scale environment",2016,"10.1002/2016MS000629","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983485991&doi=10.1002%2f2016MS000629&partnerID=40&md5=44ee641ec13077ca2401ea4e533a94d7","An uncertain representation of convective clouds has emerged as one of the key barriers to our understanding of climate sensitivity. The large gap in resolved spatial scales between General Circulation Models (GCMs) and high resolution models has made a systematic study of convective clouds across model configurations difficult. It is shown here that the simulated atmosphere of a GCM in Radiative Convective Equilibrium (RCE) is sufficiently similar across a range of domain sizes to justify the use of RCE to study both a GCM and a high resolution model on the same domain with the goal of improved constraints on the parameterized clouds. Simulations of RCE with parameterized convection have been analyzed on domains with areas spanning more than two orders of magnitude (0.80-204X106km2), all having the same grid spacing of 13km. The simulated climates on different domains are qualitatively similar in their degree of convective organization, the precipitation rates, and the vertical structure of the clouds and water vapor, with the similarity increasing as the domain size increases. Sea surface temperature perturbation experiments are used to estimate the climate feedback parameter for the differently configured experiments, and the cloud radiative effect is computed to examine the role which clouds play in the response. Despite the similar climate states between the domains the feedback parameter varies by more than a factor of two; the hydrological sensitivity parameter is better behaved, varying by a factor of 1.4. The sensitivity of the climate feedback parameter to domain size is related foremost to a nonsystematic response of low-level clouds as well as an increasingly negative longwave feedback on larger domains. © 2016. The Authors."
"55606974300;57202299549;56384704800;55802246600;7003666669;","Can nudging be used to quantify model sensitivities in precipitation and cloud forcing?",2016,"10.1002/2016MS000659","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978064545&doi=10.1002%2f2016MS000659&partnerID=40&md5=5afbcb13d2f07ea250f757d5e990e48c","Efficient simulation strategies are crucial for the development and evaluation of high-resolution climate models. This paper evaluates simulations with constrained meteorology for the quantification of parametric sensitivities in the Community Atmosphere Model version 5 (CAM5). Two parameters are perturbed as illustrating examples: the convection relaxation time scale (TAU), and the threshold relative humidity for the formation of low-level stratiform clouds (rhminl). Results suggest that the fidelity of the constrained simulations depends on the detailed implementation of nudging and the mechanism through which the perturbed parameter affects precipitation and cloud. The relative computational costs of nudged and free-running simulations are determined by the magnitude of internal variability in the physical quantities of interest, as well as the magnitude of the parameter perturbation. In the case of a strong perturbation in convection, temperature, and/or wind nudging with a 6 h relaxation time scale leads to nonnegligible side effects due to the distorted interactions between resolved dynamics and parameterized convection, while 1 year free-running simulations can satisfactorily capture the annual mean precipitation and cloud forcing sensitivities. In the case of a relatively weak perturbation in the large-scale condensation scheme, results from 1 year free-running simulations are strongly affected by natural noise, while nudging winds effectively reduces the noise, and reasonably reproduces the sensitivities. These results indicate that caution is needed when using nudged simulations to assess precipitation and cloud forcing sensitivities to parameter changes in general circulation models. We also demonstrate that ensembles of short simulations are useful for understanding the evolution of model sensitivities. © 2016. The Authors."
"55491667700;57200377027;57014949300;7203075090;","Evaluation of clouds simulated by a weather model over western India",2016,"10.1080/2150704X.2016.1195934","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976358236&doi=10.1080%2f2150704X.2016.1195934&partnerID=40&md5=4bed9535e726906cacdd2da66753713a","ABSTRACT: Cloud is one of the most crucial parameters, which influences the predictive ability of the weather models. This study is first of its kind to assess the efficiency of the numerical weather prediction (NWP) models to simulate the cloud types over Indian region. Two broadly used NWP models named as European Centre for Medium Range Weather Forecast (ECMWF) Reanalysis Interim (ERAI) and Weather Research and Forecasting (WRF) model are chosen to compare analyses and forecasts of cloud types along with cloud base height (CBH) measured from ceilometer over Ahmedabad (23.03°N, 72.5°E, 55 m amsl), India. Three months of the Indian summer monsoon period (July to September, 2014) are used for initial verifications. Results show that both the ERAI and WRF models are able to capture the cloud cover correctly over this region. This investigation has shown that the WRF model shows mostly mid-level cloud as low-level cloud, which needs further modification in WRF physics to improve the skills of cloud forecast. Further investigations of temporal variations of clouds and rainfall from in situ observations reveal that low-level multi-layer clouds provide favourable environment for rainfall. © 2016 Informa UK Limited, trading as Taylor & Francis Group."
"11939918300;7201504886;","Coupled radiative convective equilibrium simulations with explicit and parameterized convection",2016,"10.1002/2016MS000666","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990222896&doi=10.1002%2f2016MS000666&partnerID=40&md5=ff4fbe646c4093a5005116e10fe696e2","Radiative convective equilibrium has been applied in past studies to various models given its simplicity and analogy to the tropical climate. At convection-permitting resolution, the focus has been on the organization of convection that appears when using fixed sea surface temperature (SST). Here the SST is allowed to freely respond to the surface energy. The goals are to examine and understand the resulting transient behavior, equilibrium state, and perturbations thereof, as well as to compare these results to a simulation integrated with parameterized cloud and convection. Analysis shows that the coupling between the SST and the net surface energy acts to delay the onset of self-aggregation and may prevent it, in our case, for a slab ocean of less than 1 m. This is so because SST gradients tend to oppose the shallow low-level circulation that is associated with the self-aggregation of convection. Furthermore, the occurrence of self-aggregation is found to be necessary for reaching an equilibrium state and avoiding a greenhouse-like climate. In analogy to the present climate, the self-aggregation generates the dry and clear subtropics that allow the system to efficiently cool. In contrast, strong shortwave cloud radiative effects, much stronger than at convection-permitting resolution, prevent the simulation with parameterized cloud and convection to fall into a greenhouse state. The convection-permitting simulations also suggest that cloud feedbacks, as arising when perturbing the equilibrium state, may be very different, and in our case less negative, than what emerges from general circulation models. © 2016. The Authors."
"57191094832;7003908632;","Importance of Chemical Composition of Ice Nuclei on the Formation of Arctic Ice Clouds",2016,"10.1007/s00024-016-1294-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84986587251&doi=10.1007%2fs00024-016-1294-z&partnerID=40&md5=5cbf54f6fea290d36d434694529176aa","Ice clouds play an important role in the Arctic weather and climate system but interactions between aerosols, clouds and radiation remain poorly understood. Consequently, it is essential to fully understand their properties and especially their formation process. Extensive measurements from ground-based sites and satellite remote sensing reveal the existence of two Types of Ice Clouds (TICs) in the Arctic during the polar night and early spring. TICs-1 are composed by non-precipitating small (radar-unseen) ice crystals of less than 30 μm in diameter. The second type, TICs-2, are detected by radar and are characterized by a low concentration of large precipitating ice crystals ice crystals (>30 μm). To explain these differences, we hypothesized that TIC-2 formation is linked to the acidification of aerosols, which inhibits the ice nucleating properties of ice nuclei (IN). As a result, the IN concentration is reduced in these regions, resulting to a lower concentration of larger ice crystals. Water vapor available for deposition being the same, these crystals reach a larger size. Current weather and climate models cannot simulate these different types of ice clouds. This problem is partly due to the parameterizations implemented for ice nucleation. Over the past 10 years, several parameterizations of homogeneous and heterogeneous ice nucleation on IN of different chemical compositions have been developed. These parameterizations are based on two approaches: stochastic (that is nucleation is a probabilistic process, which is time dependent) and singular (that is nucleation occurs at fixed conditions of temperature and humidity and time-independent). The best approach remains unclear. This research aims to better understand the formation process of Arctic TICs using recently developed ice nucleation parameterizations. For this purpose, we have implemented these ice nucleation parameterizations into the Limited Area version of the Global Multiscale Environmental Model (GEM-LAM) and use them to simulate ice clouds observed during the Indirect and Semi-Direct Aerosol Campaign (ISDAC) in Alaska. Simulation results of the TICs-2 observed on April 15th and 25th (acidic cases) and TICs-1 observed on April 5th (non-acidic cases) are presented. Our results show that the stochastic approach based on the classical nucleation theory with the appropriate contact angle is better. Parameterizations of ice nucleation based on the singular approach tend to overestimate the ice crystal concentration in TICs-1 and TICs-2. The classical nucleation theory using the appropriate contact angle is the best approach to use to simulate the ice clouds investigated in this research. © 2016, Springer International Publishing."
"55624487771;56178431400;55714487200;55810550700;","Increasing trend of pan evaporation over the semiarid loess plateau under a warming climate",2016,"10.1175/JAMC-D-16-0041.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990818476&doi=10.1175%2fJAMC-D-16-0041.1&partnerID=40&md5=bf50fe302ed25e858f71077bc64d9ed6","In most parts of the world, pan evaporation decreases with increased air temperature rather than increases, which is known as the ""evaporation paradox."" The semiarid Loess Plateau, which is sensitive to global climate change and ecological variations, has a unique warming and drying climate. The authors of this study consider whether pan evaporation shows the same decreasing trend in this unique environment. Meteorological observations of the typical semiarid Dingxi in the Loess Plateau from 1960 to 2010 were used to analyze the variation in pan evaporation and its responses to climatic factors. It was found that the pan evaporation has increased considerably over the past 50 yr, which does not support the evaporation paradox proposed in previous studies. A multifactor model developed to simulate the independent impacts of climate factors on pan evaporation indicated that the temperature, humidity, wind speed, and low cloud cover variations contributed to pan evaporation by 46.18%, 25.90%, 2.48%, and 25.44%, respectively. The increased temperature, decreased relative humidity, and decreased low cloud cover all caused an increase in pan evaporation, unlike many parts of the world where increased low cloud cover offsets the effects of increased temperature and decreased relative humidity on pan evaporation. This may explain why the evaporation paradox occurs. If all relevant factors affecting pan evaporation are considered, it is possible the paradox will not occur. Thus in warm and drying regions, the increased pan evaporation will lead to increasingly arid conditions, which may exacerbate drought and flood disaster occurrences worldwide. © 2016 American Meteorological Society."
"36608763800;7203034123;7003390361;57190862175;42961641500;9242540400;8866821900;23768540500;8879755400;55795865800;7102495313;7003557662;6701776280;","Select strengths and biases of models in representing the Arctic winter boundary layer over sea ice: the Larcform 1 single column model intercomparison",2016,"10.1002/2016MS000630","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983523275&doi=10.1002%2f2016MS000630&partnerID=40&md5=1451ef4ea5c467d722fa5df84c8d8193","Weather and climate models struggle to represent lower tropospheric temperature and moisture profiles and surface fluxes in Arctic winter, partly because they lack or misrepresent physical processes that are specific to high latitudes. Observations have revealed two preferred states of the Arctic winter boundary layer. In the cloudy state, cloud liquid water limits surface radiative cooling, and temperature inversions are weak and elevated. In the radiatively clear state, strong surface radiative cooling leads to the build-up of surface-based temperature inversions. Many large-scale models lack the cloudy state, and some substantially underestimate inversion strength in the clear state. Here, the transformation from a moist to a cold dry air mass is modeled using an idealized Lagrangian perspective. The trajectory includes both boundary layer states, and the single-column experiment is the first Lagrangian Arctic air formation experiment (Larcform 1) organized within GEWEX GASS (Global atmospheric system studies). The intercomparison reproduces the typical biases of large-scale models: some models lack the cloudy state of the boundary layer due to the representation of mixed-phase microphysics or to the interaction between micro- and macrophysics. In some models, high emissivities of ice clouds or the lack of an insulating snow layer prevent the build-up of surface-based inversions in the radiatively clear state. Models substantially disagree on the amount of cloud liquid water in the cloudy state and on turbulent heat fluxes under clear skies. Observations of air mass transformations including both boundary layer states would allow for a tighter constraint of model behavior. © 2016. The Authors."
"19933330400;8511991900;7006270084;57188966058;55476830600;7003666669;","Coupling spectral-bin cloud microphysics with the MOSAIC aerosol model in WRF-Chem: Methodology and results for marine stratocumulus clouds",2016,"10.1002/2016MS000676","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983268201&doi=10.1002%2f2016MS000676&partnerID=40&md5=0082ba464c8ab832e751e66e86454262","Aerosol-cloud interaction processes can be represented more physically with bin cloud microphysics relative to bulk microphysical parameterizations. However, due to computational power limitations in the past, bin cloud microphysics was often run with very simple aerosol treatments. The purpose of this study is to represent better aerosol-cloud interaction processes in the Chemistry version of Weather Research and Forecast model (WRF-Chem) at convection-permitting scales by coupling spectral-bin cloud microphysics (SBM) with the MOSAIC sectional aerosol model. A flexible interface is built that exchanges cloud and aerosol information between them. The interface contains a new bin aerosol activation approach, which replaces the treatments in the original SBM. It also includes the modified aerosol resuspension and in-cloud wet removal processes with the droplet loss tendencies and precipitation fluxes from SBM. The newly coupled system is evaluated for two marine stratocumulus cases over the Southeast Pacific Ocean with either a simplified aerosol setup or full-chemistry. We compare the aerosol activation process in the newly coupled SBM-MOSAIC against the SBM simulation without chemistry using a simplified aerosol setup, and the results show consistent activation rates. A longer time simulation reinforces that aerosol resuspension through cloud drop evaporation plays an important role in replenishing aerosols and impacts cloud and precipitation in marine stratocumulus clouds. Evaluation of the coupled SBM-MOSAIC with full-chemistry using aircraft measurements suggests that the new model works realistically for the marine stratocumulus clouds, and improves the simulation of cloud microphysical properties compared to a simulation using MOSAIC coupled with the Morrison two-moment microphysics. © 2016. The Authors."
"35095671300;6507477526;7004762055;6602940714;","The response of clouds and aerosols to cosmic ray decreases",2016,"10.1002/2016JA022689","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992096780&doi=10.1002%2f2016JA022689&partnerID=40&md5=325f9e42b9a5939ed88b3792a9b3a2c9","A method is developed to rank Forbush decreases (FDs) in the galactic cosmic ray radiation according to their expected impact on the ionization of the lower atmosphere. Then a Monte Carlo bootstrap-based statistical test is formulated to estimate the significance of the apparent response in physical and microphysical cloud parameters to FDs. The test is subsequently applied to one ground-based and three satellite-based data sets. Responses (&gt;95%) to FDs are found in the following parameters of the analyzed data sets. AERONET: Ångström exponent (cloud condensation nuclei changes), SSM/I: liquid water content, International Satellite Cloud Climate Project (ISCCP): total, high, and middle, IR-detected clouds over the oceans, Moderate Resolution Imaging Spectroradiometer (MODIS): cloud effective emissivity, cloud optical thickness, liquid water, cloud fraction, liquid water path, and liquid cloud effective radius. Moreover, the responses in MODIS are found to correlate positively with the strength of the FDs, and the signs and magnitudes of the responses agree with model-based expectations. The effect is mainly seen in liquid clouds. An impact through changes in UV-driven photo chemistry is shown to be negligible and an impact via UV absorption in the stratosphere is found to have no effect on clouds. The total solar irradiance has a relative decrease in connection with FDs of the order of 10−3, which is too small to have a thermodynamic impact on timescales of a few days. The results demonstrate that there is a real influence of FDs on clouds probably through ions. ©2016. American Geophysical Union. All Rights Reserved."
"57190585228;23991212200;","Effects of explicit convection on global land-atmosphere coupling in the superparameterized CAM",2016,"10.1002/2016MS000689","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981306463&doi=10.1002%2f2016MS000689&partnerID=40&md5=4396a465f99632c78fe52d4c5ae0e6fe","Conventional global climate models are prone to producing unrealistic land-atmosphere coupling signals. Cumulus and convection parameterizations are natural culprits but the effect of bypassing them with explicitly resolved convection on global land-atmosphere coupling dynamics has not been explored systematically. We apply a suite of modern land-atmosphere coupling diagnostics to isolate the effect of cloud Superparameterization in the Community Atmosphere Model (SPCAM) v3.5, focusing on both the terrestrial segment (i.e., soil moisture and surface turbulent fluxes interaction) and atmospheric segment (i.e., surface turbulent fluxes and precipitation interaction) in the water pathway of the land-atmosphere feedback loop. At daily timescales, SPCAM produces stronger uncoupled terrestrial signals (negative sign) over tropical rainforests in wet seasons, reduces the terrestrial coupling strength in the Central Great Plain in American, and reverses the coupling sign (from negative to positive) over India in the boreal summer season—all favorable improvements relative to reanalysis-forced land modeling. Analysis of the triggering feedback strength (TFS) and amplification feedback strength (AFS) shows that SPCAM favorably reproduces the observed geographic patterns of these indices over North America, with the probability of afternoon precipitation enhanced by high evaporative fraction along the eastern United States and Mexico, while conventional CAM does not capture this signal. We introduce a new diagnostic called the Planetary Boundary Layer (PBL) Feedback Strength (PFS), which reveals that SPCAM exhibits a tight connection between the responses of the lifting condensation level, the PBL height, and the rainfall triggering to surface turbulent fluxes; a triggering disconnect is found in CAM. © 2016. The Authors."
"55469523400;15124698700;","Scaling of the entropy budget with surface temperature in radiative-convective equilibrium",2016,"10.1002/2016MS000673","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979735717&doi=10.1002%2f2016MS000673&partnerID=40&md5=0c627f56c07fe9e7ce9ba554fe545afb","The entropy budget of the atmosphere is examined in simulations of radiative-convective equilibrium with a cloud-system resolving model over a wide range of surface temperatures from 281 to 311 K. Irreversible phase changes and the diffusion of water vapor account for more than half of the irreversible entropy production within the atmosphere, even in the coldest simulation. As the surface temperature is increased, the atmospheric radiative cooling rate increases, driving a greater entropy sink that must be matched by greater irreversible entropy production. The entropy production resulting from irreversible moist processes increases at a similar fractional rate as the entropy sink and at a lower rate than that implied by Clausius-Clapeyron scaling. This allows the entropy production from frictional drag on hydrometeors and on the atmospheric flow to also increase with warming, in contrast to recent results for simulations with global climate models in which the work output decreases with warming. A set of approximate scaling relations is introduced for the terms in the entropy budget as the surface temperature is varied, and many of the terms are found to scale with the mean surface precipitation rate. The entropy budget provides some insight into changes in frictional dissipation in response to warming or changes in model resolution, but it is argued that frictional dissipation is not closely linked to other measures of convective vigor. © 2016. The Authors."
"35490828000;16041047000;15729547600;56768110900;7003627515;","Present-day and future Antarctic ice sheet climate and surface mass balance in the Community Earth System Model",2016,"10.1007/s00382-015-2907-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983223885&doi=10.1007%2fs00382-015-2907-4&partnerID=40&md5=2a233c2f1170870cfed1226c41244abe","We present climate and surface mass balance (SMB) of the Antarctic ice sheet (AIS) as simulated by the global, coupled ocean–atmosphere–land Community Earth System Model (CESM) with a horizontal resolution of ∼ 1 ∘ in the past, present and future (1850–2100). CESM correctly simulates present-day Antarctic sea ice extent, large-scale atmospheric circulation and near-surface climate, but fails to simulate the recent expansion of Antarctic sea ice. The present-day Antarctic ice sheet SMB equals 2280 ± 131 Gtyear-1, which concurs with existing independent estimates of AIS SMB. When forced by two CMIP5 climate change scenarios (high mitigation scenario RCP2.6 and high-emission scenario RCP8.5), CESM projects an increase of Antarctic ice sheet SMB of about 70 Gtyear-1 per degree warming. This increase is driven by enhanced snowfall, which is partially counteracted by more surface melt and runoff along the ice sheet’s edges. This intensifying hydrological cycle is predominantly driven by atmospheric warming, which increases (1) the moisture-carrying capacity of the atmosphere, (2) oceanic source region evaporation, and (3) summer AIS cloud liquid water content. © 2016, The Author(s)."
"54904504200;39862506900;8557387300;6506298579;6602887222;","Projected changes in medicanes in the HadGEM3 N512 high-resolution global climate model",2016,"10.1007/s00382-015-2941-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84951868084&doi=10.1007%2fs00382-015-2941-2&partnerID=40&md5=5ea1d4b760a38f9622a5ccb69f6644a1","Medicanes or “Mediterranean hurricanes” represent a rare and physically unique type of Mediterranean mesoscale cyclone. There are similarities with tropical cyclones with regard to their development (based on the thermodynamical disequilibrium between the warm sea and the overlying troposphere) and their kinematic and thermodynamical properties (medicanes are intense vortices with a warm core and even a cloud-free eye). Although medicanes are smaller and their wind speeds are lower than in tropical cyclones, the severity of their winds can cause substantial damage to islands and coastal areas. Concern about how human-induced climate change will affect extreme events is increasing. This includes the future impacts on medicanes due to the warming of the Mediterranean waters and the projected changes in regional atmospheric circulation. However, most global climate models do not have high enough spatial resolution to adequately represent small features such as medicanes. In this study, a cyclone tracking algorithm is applied to high resolution global climate model data with a horizontal grid resolution of approximately 25 km over the Mediterranean region. After a validation of the climatology of general Mediterranean mesoscale cyclones, changes in medicanes are determined using climate model experiments with present and future forcing. The magnitude of the changes in the winds, frequency and location of medicanes is assessed. While no significant changes in the total number of Mediterranean mesoscale cyclones are found, medicanes tend to decrease in number but increase in intensity. The model simulation suggests that medicanes tend to form more frequently in the Gulf of Lion–Genoa and South of Sicily. © 2015, Springer-Verlag Berlin Heidelberg."
"23490082500;55650183600;7402874543;","End-cretaceous cooling and mass extinction driven by a dark cloud encounter",2016,"10.1016/j.gr.2015.12.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961223625&doi=10.1016%2fj.gr.2015.12.004&partnerID=40&md5=fb67473bb018f3e38f9cf81e4cf91350","We have identified iridium in an ~ 5 m-thick section of pelagic sediment cored in the deep sea floor at Site 886C, in addition to a distinct spike in iridium at the K–Pg boundary related to the Chicxulub asteroid impact. We distinguish the contribution of the extraterrestrial matter in the sediments from those of the terrestrial matter through a Co–Ir diagram, calling it the “extraterrestrial index” fEX. This new index reveals a broad iridium anomaly around the Chicxulub spike. Any mixtures of materials on the surface of the Earth cannot explain the broad iridium component. On the other hand, we find that an encounter of the solar system with a giant molecular cloud can aptly explain the component, especially if the molecular cloud has a size of ~ 100 pc and the central density of over 2000 protons/cm3. Kataoka et al. (2013, 2014) pointed that an encounter with a dark cloud would drive an environmental catastrophe leading to mass extinction. Solid particles from the hypothesized dark cloud would combine with the global environment of Earth, remaining in the stratosphere for at least several months or years. With a sunshield effect estimated to be as large as − 9.3 W m− 2, the dark cloud would have caused global climate cooling in the last 8 Myr of the Cretaceous period, consistent with the variations of stable isotope ratios in oxygen (Barrera and Huber, 1990; Li and Keller, 1998; Barrera and Savin, 1999; Li and Keller, 1999) and strontium (Barrera and Huber, 1990; Ingram, 1995; Sugarman et al., 1995). The resulting growth of the continental ice sheet also resulted in a regression of the sea level. The global cooling, which appears to be associated with a decrease in the diversity of fossils, eventually led to the mass extinction at the K–Pg boundary. © 2016 The Authors"
"50560994200;57194330191;57194332139;55273559900;57190741703;23486592200;","Aboveground biomass estimation of individual trees in a coastal planted forest using full-waveform airborne laser scanning data",2016,"10.3390/rs8090729","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019707489&doi=10.3390%2frs8090729&partnerID=40&md5=2e4cf2ba802a714de1572e15a40c03ce","The accurate estimation of individual tree level aboveground biomass (AGB) is critical for understanding the carbon cycle, detecting potential biofuels and managing forest ecosystems. In this study, we assessed the capability of the metrics of point clouds, extracted from the full-waveform Airborne Laser Scanning (ALS) data, and of composite waveforms, calculated based on a voxel-based approach, for estimating tree level AGB individually and in combination, over a planted forest in the coastal region of east China. To do so, we investigated the importance of point cloud and waveform metrics for estimating tree-level AGB by all subsets models and relative weight indices. We also assessed the capability of the point cloud and waveform metrics based models and combo model (including the combination of both point cloud and waveform metrics) for tree-level AGB estimation and evaluated the accuracies of these models. The results demonstrated that most of the waveform metrics have relatively low correlation coefficients (&lt;0.60) with other metrics. The combo models (Adjusted R2 = 0.78-0.89), including both point cloud and waveform metrics, have a relatively higher performance than the models fitted by point cloud metrics-only (Adjusted R2 = 0.74-0.86) and waveform metrics-only (Adjusted R2 = 0.72-0.84), with the mostly selected metrics of the 95th percentile height (H95), mean of height of median energy (HOMEμ) and mean of the height/median ratio (HTMRμ). Based on the relative weights (i.e., the percentage of contribution for R2) of the mostly selected metrics for all subsets, the metric of 95th percentile height (H95) has the highest relative importance for AGB estimation (19.23%), followed by 75th percentile height (H75) (18.02%) and coefficient of variation of heights (Hcv) (15.18%) in the point cloud metrics based models. For the waveform metrics based models, the metric of mean of height of median energy (HOMEμ) has the highest relative importance for AGB estimation (17.86%), followed by mean of the height/median ratio (HTMRμ) (16.23%) and standard deviation of height of median energy (HOMEσ) (14.78%). This study demonstrated benefits of using full-waveform ALS data for estimating biomass at tree level, for sustainable forest management and mitigating climate change by planted forest, as China has the largest area of planted forest in the world, and these forests contribute to a large amount of carbon sequestration in terrestrial ecosystems. © 2016 by the authors."
"8719703500;36842724800;","A probabilistic multispectral pattern recognition method for detection of overshooting cloud tops using passive satellite imager observations",2016,"10.1175/JAMC-D-15-0249.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990866322&doi=10.1175%2fJAMC-D-15-0249.1&partnerID=40&md5=f9fd9b03254437ca7c02a37f39c0c04b","Deep convective updrafts often penetrate through the surrounding cirrus anvil and into the lower stratosphere. Cross-tropopause transport of ice, water vapor, and chemicals occurs within these ""overshooting tops"" (OTs) along with a variety of hazardous weather conditions. OTs are readily apparent in satellite imagery, and, given the importance of OTs for weather and climate, a number of automated satellite-based detection methods have been developed. Some of these methods have proven to be relatively reliable, and their products are used in diverse Earth science applications. Nevertheless, analysis of these methods and feedback from product users indicate that use of fixed infrared temperature-based detection criteria often induces biases that can limit their utility for weather and climate analysis. This paper describes a new multispectral OT detection approach that improves upon those previously developed by minimizing use of fixed criteria and incorporating pattern recognition analyses to arrive at an OT probability product. The product is developed and validated using OT and non-OT anvil regions identified by a human within MODIS imagery. The product offered high skill for discriminating between OTs and anvils and matched 69% of human OT identifications for a particular probability threshold with a false-detection rate of 18%, outperforming previously existing methods. The false-detection rate drops to 1% when OT-induced texture detected within visible imagery is used to constrain the IR-based OT probability product. The OT probability product is also shown to improve severe-storm detection over the United States by 20% relative to the best existing method. © 2016 American Meteorological Society."
"56242059600;6507400558;7004978125;","Stochasticity of convection in Giga-LES data",2016,"10.1007/s00382-015-2936-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983260392&doi=10.1007%2fs00382-015-2936-z&partnerID=40&md5=9961159aede0f1df9fd0ae206cfcd3b4","The poor representation of tropical convection in general circulation models (GCMs) is believed to be responsible for much of the uncertainty in the predictions of weather and climate in the tropics. The stochastic multicloud model (SMCM) was recently developed by Khouider et al. (Commun Math Sci 8(1):187–216, 2010) to represent the missing variability in GCMs due to unresolved features of organized tropical convection. The SMCM is based on three cloud types (congestus, deep and stratiform), and transitions between these cloud types are formalized in terms of probability rules that are functions of the large-scale environment convective state and a set of seven arbitrary cloud timescale parameters. Here, a statistical inference method based on the Bayesian paradigm is applied to estimate these key cloud timescales from the Giga-LES dataset, a 24-h large-eddy simulation (LES) of deep tropical convection (Khairoutdinov et al. in J Adv Model Earth Syst 1(12), 2009) over a domain comparable to a GCM gridbox. A sequential learning strategy is used where the Giga-LES domain is partitioned into a few subdomains, and atmospheric time series obtained on each subdomain are used to train the Bayesian procedure incrementally. Convergence of the marginal posterior densities for all seven parameters is demonstrated for two different grid partitions, and sensitivity tests to other model parameters are also presented. A single column model simulation using the SMCM parameterization with the Giga-LES inferred parameters reproduces many important statistical features of the Giga-LES run, without any further tuning. In particular it exhibits intermittent dynamical behavior in both the stochastic cloud fractions and the large scale dynamics, with periods of dry phases followed by a coherent sequence of congestus, deep, and stratiform convection, varying on timescales of a few hours consistent with the Giga-LES time series. The chaotic variations of the cloud area fractions were captured fairly well both qualitatively and quantitatively demonstrating the stochastic nature of convection in the Giga-LES simulation. © 2015, Springer-Verlag Berlin Heidelberg."
"35146599100;11839212900;57194324576;57192697237;56422113300;6505468200;7801472628;","Tree species classification in temperate forests using Formosat-2 satellite image time series",2016,"10.3390/rs8090734","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016832978&doi=10.3390%2frs8090734&partnerID=40&md5=9f5e5dbd68c19f6041716c54ed572ed6","Mapping forest composition is a major concern for forest management, biodiversity assessment and for understanding the potential impacts of climate change on tree species distribution. In this study, the suitability of a dense high spatial resolution multispectral Formosat-2 satellite image time-series (SITS) to discriminate tree species in temperate forests is investigated. Based on a 17-date SITS acquired across one year, thirteen major tree species (8 broadleaves and 5 conifers) are classified in a study area of southwest France. The performance of parametric (GMM) and nonparametric (k-NN, RF, SVM) methods are compared at three class hierarchy levels for different versions of the SITS: (i) a smoothed noise-free version based on the Whittaker smoother; (ii) a non-smoothed cloudy version including all the dates; (iii) a non-smoothed noise-free version including only 14 dates. Noise refers to pixels contaminated by clouds and cloud shadows. The results of the 108 distinct classifications show a very high suitability of the SITS to identify the forest tree species based on phenological differences (average κ = 0.93 estimated by cross-validation based on 1235 field-collected plots). SVM is found to be the best classifier with very close results from the other classifiers. No clear benefit of removing noise by smoothing can be observed. Classification accuracy is even improved using the non-smoothed cloudy version of the SITS compared to the 14 cloud-free image time series. However conclusions of the results need to be considered with caution because of possible overfitting. Disagreements also appear between the maps produced by the classifiers for complex mixed forests, suggesting a higher classification uncertainty in these contexts. Our findings suggest that time-series data can be a good alternative to hyperspectral data for mapping forest types. It also demonstrates the potential contribution of the recently launched Sentinel-2 satellite for studying forest ecosystems. © 2016 by the authors."
"56953933900;13611521400;26028728800;55571466300;37121520200;55760862100;","MJO prediction skill, predictability, and teleconnection impacts in the Beijing Climate Center Atmospheric General Circulation Model",2016,"10.1016/j.dynatmoce.2016.06.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975470612&doi=10.1016%2fj.dynatmoce.2016.06.001&partnerID=40&md5=d08b3d42bc8d83f8721a1b5713d937f0","This study evaluates performance of Madden-Julian oscillation (MJO) prediction in the Beijing Climate Center Atmospheric General Circulation Model (BCC_AGCM2.2). By using the real-time multivariate MJO (RMM) indices, it is shown that the MJO prediction skill of BCC_AGCM2.2 extends to about 16-17 days before the bivariate anomaly correlation coefficient drops to 0.5 and the root-mean-square error increases to the level of the climatological prediction. The prediction skill showed a seasonal dependence, with the highest skill occurring in boreal autumn, and a phase dependence with higher skill for predictions initiated from phases 2-4. The results of the MJO predictability analysis showed that the upper bounds of the prediction skill can be extended to 26 days by using a single-member estimate, and to 42 days by using the ensemble-mean estimate, which also exhibited an initial amplitude and phase dependence. The observed relationship between the MJO and the North Atlantic Oscillation was accurately reproduced by BCC_AGCM2.2 for most initial phases of the MJO, accompanied with the Rossby wave trains in the Northern Hemisphere extratropics driven by MJO convection forcing. Overall, BCC_AGCM2.2 displayed a significant ability to predict the MJO and its teleconnections without interacting with the ocean, which provided a useful tool for fully extracting the predictability source of subseasonal prediction. © 2016 The Author(s)."
"35734944400;6701862401;56585354800;6602996168;6507981312;56942509000;41461547100;56048254100;56512232400;6603250042;6603744207;7101618025;6602150900;6603640442;7003745922;6507912242;","2014 iAREA campaign on aerosol in Spitsbergen - Part 2: Optical properties from Raman-lidar and in-situ observations at Ny-Ålesund",2016,"10.1016/j.atmosenv.2016.05.053","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975486527&doi=10.1016%2fj.atmosenv.2016.05.053&partnerID=40&md5=1342824470206f8676d8fa0b4a2a6cb7","In this work multi wavelength Raman lidar data from Ny-Ålesund, Spitsbergen have been analysed for the spring 2014 Arctic haze season, as part of the iAREA campaign. Typical values and probability distributions for aerosol backscatter, extinction and depolarisation, the lidar ratio and the color ratio for 4 different altitude intervals within the troposphere are given. These quantities and their dependencies are analysed and the frequency of altitude-dependent observed aerosol events are given. A comparison with ground-based size distribution and chemical composition is performed. Hence the aim of this paper is to provide typical and statistically meaningful properties of Arctic aerosol, which may be used in climate models or to constrain the radiative forcing. We have found that the 2014 season was only moderately polluted with Arctic haze and that sea salt and sulphate were the most dominant aerosol species. Moreover the drying of an aerosol layer after cloud disintegration has been observed. Hardly any clear temporal evolution over the 4 week data set on Arctic haze is obvious with the exception of the extinction coefficient and the lidar ratio, which significantly decreased below 2 km altitude by end April. In altitudes between 2 and 5 km the haze season lasted longer and the aerosol properties were generally more homogeneous than closer to the surface. Above 5 km only few particles were found. The variability of the lidar ratio is discussed. It was found that knowledge of the aerosol's size and shape does not determine the lidar ratio. Contrary to shape and lidar ratio, there is a clear correlation between size and backscatter: larger particles show a higher backscatter coefficient. © 2016 The Authors."
"7103232081;15125216700;7004214645;6604021707;9242539000;56203249800;55408944000;9242540400;56528677800;55339475000;7202684687;12240390300;","Modeling the QBO—Improvements resulting from higher-model vertical resolution",2016,"10.1002/2016MS000699","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978904008&doi=10.1002%2f2016MS000699&partnerID=40&md5=91df5d49ee681b32016998904446c996","Using the NASA Goddard Institute for Space Studies (GISS) climate model, it is shown that with proper choice of the gravity wave momentum flux entering the stratosphere and relatively fine vertical layering of at least 500 m in the upper troposphere-lower stratosphere (UTLS), a realistic stratospheric quasi-biennial oscillation (QBO) is modeled with the proper period, amplitude, and structure down to tropopause levels. It is furthermore shown that the specified gravity wave momentum flux controls the QBO period whereas the width of the gravity wave momentum flux phase speed spectrum controls the QBO amplitude. Fine vertical layering is required for the proper downward extension to tropopause levels as this permits wave-mean flow interactions in the UTLS region to be resolved in the model. When vertical resolution is increased from 1000 to 500 m, the modeled QBO modulation of the tropical tropopause temperatures increasingly approach that from observations, and the “tape recorder” of stratospheric water vapor also approaches the observed. The transport characteristics of our GISS models are assessed using age-of-air and N2O diagnostics, and it is shown that some of the deficiencies in model transport that have been noted in previous GISS models are greatly improved for all of our tested model vertical resolutions. More realistic tropical-extratropical transport isolation, commonly referred to as the “tropical pipe,” results from the finer vertical model layering required to generate a realistic QBO. © 2016. The Authors."
"7005729142;7003821079;7202962414;","Toward improving ice water content and snow-rate retrievals from radars. Part I: X and W bands, emphasizing cloudsat",2016,"10.1175/JAMC-D-15-0290.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84990841881&doi=10.1175%2fJAMC-D-15-0290.1&partnerID=40&md5=c4d59b1acc44821ed316f89153c026f7","Microphysical data and radar reflectivities (Ze, -15 &lt; Ze &lt; 10 dB) measured from flights during the NASA Tropical Clouds, Convection, Chemistry and Climate field program are used to relate Ze at X and W band to measured ice water content (IWC). Because nearly collocated Ze and IWC were each directly measured, Ze-IWC relationships could be developed directly. Using the particle size distributions and ice particle masses evaluated based on the direct IWC measurements, reflectivity-snowfall rate (Ze-S) relationships were also derived. For -15 &lt; Ze &lt; 10 dB, the relationships herein yield larger IWC and S than given by the retrievals and earlier relationships. The sensitivity of radar reflectivity to particle size distribution and size-dependent mass, shape, and orientation introduces significant uncertainties in retrieved quantities since these factors vary substantially globally. To partially circumvent these uncertainties, a W-band Ze-S relationship is developed by relating four years of global CloudSat reflectivity observations measured immediately above the melting layer to retrieved rain rates at the base of the melting layer. The supporting assumptions are that the water mass flux is constant through the melting layer, that the air temperature is nearly 0°C, and that the retrieved rain rates are well constrained. Where Ze &gt; 10 dB, this Ze-S relationship conforms well to earlier relationships, but for Ze &lt; 10 dB it yields higher IWC and S. Because not all retrieval algorithms estimate either or both IWC and S, the authors use a large aircraft-derived dataset to relate IWC and S. The IWC can then be estimated from S and vice versa. © 2016 American Meteorological Society."
"7102358267;56429674100;56037741700;55715899800;35274839300;7005923344;56923805700;7004239407;","Dimethyl sulfide and other biogenic volatile organic compound emissions from branching coral and reef seawater: potential sources of secondary aerosol over the Great Barrier Reef",2016,"10.1007/s10874-016-9327-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955282935&doi=10.1007%2fs10874-016-9327-7&partnerID=40&md5=954bd46c892b782ee2a101560af3f396","Volatile organic compounds (VOCs) in the headspace of bubble chambers containing branches of live coral in filtered reef seawater were analysed using gas chromatography with mass spectrometry (GC-MS). When the coral released mucus it was a source of dimethyl sulfide (DMS) and isoprene; however, these VOCs were not emitted to the chamber headspace from mucus-free coral. This finding, which suggests that coral is an intermittent source of DMS and isoprene, was supported by the observation of occasional large pulses of atmospheric DMS (DMSa) over Heron Island reef on the southern Great Barrier Reef (GBR), Australia, in the austral winter. The highest DMSa pulse (320 ppt) was three orders of magnitude less than the DMS mixing ratio (460 ppb) measured in the headspace of a dynamically purged bubble chamber containing a mucus-coated branch of Acropora aspera indicating that coral reefs can be strong point sources of DMSa. Static headspace GC-MS analysis of coral fragments identified mainly DMS and seven other minor reduced sulfur compounds including dimethyl disulfide, methyl mercaptan, and carbon disulfide, while coral reef seawater was an indicated source of methylene chloride, acetone, and methyl ethyl ketone. The VOCs emitted by coral and reef seawater are capable of producing new atmospheric particles &lt; 15 nm diameter as observed at Heron Island reef. DMS and isoprene are known to play a role in low-level cloud formation, so aerosol precursors such as these could influence regional climate through a sea surface temperature regulation mechanism hypothesized to operate over the GBR. © 2016, Springer Science+Business Media Dordrecht."
"55543240500;55803438700;7404544551;7406684798;54684752900;55644969600;","Consideration of land use change-induced surface albedo effects in life-cycle analysis of biofuels",2016,"10.1039/c6ee01728b","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984887286&doi=10.1039%2fc6ee01728b&partnerID=40&md5=45bf7ddac21d24ff2755faabffd5282b","Land use change (LUC)-induced surface albedo effects for expansive biofuel production need to be quantified for improved understanding of biofuel climate impacts. We addressed this emerging issue for expansive biofuel production in the United States (U.S.) and compared the albedo effects with greenhouse gas emissions highlighted by traditional life-cycle analysis of biofuels. We used improved spatial representation of albedo effects in our analysis by obtaining over 1.4 million albedo observations from the Moderate Resolution Imaging Spectroradiometer flown on NASA satellites over a thousand counties representative of six Agro-Ecological Zones (AEZs) in the U.S. We utilized high-spatial-resolution, crop-specific cropland cover data from the U.S. Department of Agriculture and paired the data with the albedo data to enable consideration of various LUC scenarios. We simulated the radiative effects of LUC-induced albedo changes for seven types of crop covers using the Monte Carlo Aerosol, Cloud and Radiation model, which employs an advanced radiative transfer mechanism coupled with spatially and temporally resolved meteorological and aerosol conditions. These simulations estimated the net radiative fluxes at the top of the atmosphere as a result of the LUC-induced albedo changes, which enabled quantification of the albedo effects on the basis of radiative forcing defined by the Intergovernmental Panel on Climate Change for CO2 and other greenhouse gases effects. Finally, we quantified the LUC-induced albedo effects for production of ethanol from corn, miscanthus, and switchgrass in different AEZs of the U.S. Results show that the weighted national average albedo effect is a small cooling effect of -1.8 g CO2 equivalent (CO2e) for a mega-Joule (MJ) of corn ethanol, a relatively stronger warming effect of 12.1 g CO2e per MJ of switchgrass ethanol, and a small warming effect of 2.7 g CO2e per MJ of miscanthus ethanol. Significant variations in albedo-induced effects are found among different land conversions for the same biofuel, and among different AEZ regions for the same land conversion and biofuel. This spatial heterogeneity, owing to non-linear albedo dynamics and radiation processes, suggests highly variable LUC-induced albedo effects depending on geographical locations and vegetation. These findings provide new insights on potential climate effects by producing biofuels through considering biogeophysical as well as biogeochemical effects of biofuel production and use in the U.S. © 2016 The Royal Society of Chemistry."
"36446796300;57203460307;17343754500;24399902600;55683214500;21742642500;57198936476;20434553000;55320586600;55992351500;57202473308;6604085656;7003279414;6602688853;6602797994;57202484220;7003650034;6602126569;","Global surface net-radiation at 5 km from MODIS Terra",2016,"10.3390/rs8090739","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019725771&doi=10.3390%2frs8090739&partnerID=40&md5=55f7235adb7535dd1a221773654886d1","Reliable and fine resolution estimates of surface net-radiation are required for estimating latent and sensible heat fluxes between the land surface and the atmosphere. However, currently, fine resolution estimates of net-radiation are not available and consequently it is challenging to develop multi-year estimates of evapotranspiration at scales that can capture land surface heterogeneity and are relevant for policy and decision-making. We developed and evaluated a global net-radiation product at 5 km and 8-day resolution by combining mutually consistent atmosphere and land data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board Terra. Comparison with net-radiation measurements from 154 globally distributed sites (414 site-years) from the FLUXNET and Surface Radiation budget network (SURFRAD) showed that the net-radiation product agreed well with measurements across seasons and climate types in the extratropics (Wilmott's index ranged from 0.74 for boreal to 0.63 for Mediterranean sites). Mean absolute deviation between the MODIS and measured net-radiation ranged from 38.0 ± 1.8 W.m-2 in boreal to 72.0 ± 4.1 W.m-2 in the tropical climates. The mean bias was small and constituted only 11%, 0.7%, 8.4%, 4.2%, 13.3%, and 5.4% of the mean absolute error in daytime net-radiation in boreal, Mediterranean, temperate-continental, temperate, semi-arid, and tropical climate, respectively. To assess the accuracy of the broader spatiotemporal patterns, we upscaled error-quantified MODIS net-radiation and compared it with the net-radiation estimates from the coarse spatial (1° x 1°) but high temporal resolution gridded net-radiation product from the Clouds and Earth's Radiant Energy System (CERES). Our estimates agreed closely with the net-radiation estimates from the CERES. Difference between the two was less than 10W.m-22 in 94% of the total land area. MODIS net-radiation product will be a valuable resource for the science community studying turbulent fluxes and energy budget at the Earth's surface. © 2016 by the authors."
"7103180783;7402401574;57087451200;56228672600;7402969850;55737749900;","Abrupt summer warming and changes in temperature extremes over Northeast Asia since the mid-1990s: Drivers and physical processes",2016,"10.1007/s00376-016-5247-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979079606&doi=10.1007%2fs00376-016-5247-3&partnerID=40&md5=41dbd80727b36a5c9e8aba401f5b2123","This study investigated the drivers and physical processes for the abrupt decadal summer surface warming and increases in hot temperature extremes that occurred over Northeast Asia in the mid-1990s. Observations indicate an abrupt increase in summer mean surface air temperature (SAT) over Northeast Asia since the mid-1990s. Accompanying this abrupt surface warming, significant changes in some temperature extremes, characterized by increases in summer mean daily maximum temperature (Tmax), daily minimum temperature (Tmin), annual hottest day temperature (TXx), and annual warmest night temperature (TNx) were observed. There were also increases in the frequency of summer days (SU) and tropical nights (TR). Atmospheric general circulation model experiments forced by changes in sea surface temperature (SST)/sea ice extent (SIE), anthropogenic greenhouse gas (GHG) concentrations, and anthropogenic aerosol (AA) forcing, relative to the period 1964–93, reproduced the general patterns of observed summer mean SAT changes and associated changes in temperature extremes, although the abrupt decrease in precipitation since the mid-1990s was not simulated. Additional model experiments with different forcings indicated that changes in SST/SIE explained 76% of the area-averaged summer mean surface warming signal over Northeast Asia, while the direct impact of changes in GHG and AA explained the remaining 24% of the surface warming signal. Analysis of physical processes indicated that the direct impact of the changes in AA (through aerosol–radiation and aerosol–cloud interactions), mainly related to the reduction of AA precursor emissions over Europe, played a dominant role in the increase in TXx and a similarly important role as SST/SIE changes in the increase in the frequency of SU over Northeast Asia via AA-induced coupled atmosphere–land surface and cloud feedbacks, rather than through a direct impact of AA changes on cloud condensation nuclei. The modelling results also imply that the abrupt summer surface warming and increases in hot temperature extremes over Northeast Asia since the mid-1990s will probably sustain in the next few decades as GHG concentrations continue to increase and AA precursor emissions over both North America and Europe continue to decrease. © 2016, Science Press."
"56267602600;7201519079;24461654300;","Precipitation recycling and soil–precipitation interaction across the arid and semi-arid regions of China",2016,"10.1002/joc.4586","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84954271048&doi=10.1002%2fjoc.4586&partnerID=40&md5=acefb1ca632531fe11434d90fe46c46d","Dynamic recycling model (DRM) and reanalysis data were used to study the interaction between the land surface and atmosphere during the warm season from 1979 to 2010 across the arid and semi-arid regions of China. The nonlinear trends common to the key land–atmosphere interaction variables were extracted. For the whole study region, the precipitation recycling ratio showed an increasing trend, especially in the period before the 1990s. Simultaneously, increasing trends were also found in variables regionally related to precipitation, such as soil moisture, evaporation, precipitation efficiency, low-level cloud and precipitable water. However, the moisture transport due to westerly moisture flux showed a remarkable weakening throughout the whole study region. Based on significantly positive correlation between the precipitation efficiency and precipitation recycling ratio under relatively low moisture advection, it was concluded that the precipitation recycling process should not been ignored, for both direct and indirect precipitation processes, in the study region. The spatial patterns of nonlinear trends in land–atmosphere interaction variables indicated reverse tendencies in two sub-regions divided by the meridional boundary at approximately 110°E. For the western sub-region, although decreasing westerly moisture flow was found, the strengthening southerly moisture flux mainly resulted in an increase of precipitable water. Positive relationships among precipitable water, low cloud, precipitation, soil moisture, evaporation and the precipitation recycling ratio were also found. The soil becoming wetter and the precipitation recycling process becoming enhanced suggested the existence of positive land–atmosphere interaction in the western sub-region. However, the opposite tendencies were found in the eastern sub-region, where a weakening of advected moisture convergence was caused by decreases in both westerly and southerly moisture transport. Furthermore, less evaporation and warming temperatures suggested the climate in the eastern sub-region shifted towards relatively warmer and drier conditions throughout the course of the study period. © 2016 Royal Meteorological Society"
"8836278700;36984127300;35577097300;","Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts",2016,"10.1016/j.scitotenv.2016.03.246","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966320702&doi=10.1016%2fj.scitotenv.2016.03.246&partnerID=40&md5=d00aad26ed343f1b9db026597faa2581","Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~15-15,000 nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter &lt;100 nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167 nm and 1150 to 1760 nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from ultrafine particles to accumulation sizes varied between 1 and 15 nm h-1, with mean growth rate of ~7.35 ± 2.93 nm h-1. © 2016 Elsevier B.V."
"57193840197;6506383700;36047973900;6506180220;57217352376;24757981500;6603684021;","Atmospheric heating due to black carbon aerosol during the summer monsoon period over Ballia: A rural environment over Indo-Gangetic Plain",2016,"10.1016/j.atmosres.2016.04.008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966431202&doi=10.1016%2fj.atmosres.2016.04.008&partnerID=40&md5=4590f222fd6585329271471e6606b806","Black carbon (BC) aerosols are one of the most uncertain drivers of global climate change. The prevailing view is that BC mass concentrations are low in rural areas where industrialization and vehicular emissions are at a minimum. As part of a national research program called the ""Ganga Basin Ground Based Experiment-2014 under the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) Phase-III"" of Ministry of Earth Sciences, Government of India, the continuous measurements of BC and particulate matter (PM) mass concentrations, were conducted in a rural environment in the highly-polluted Indo-Gangetic Plain region during 16th June to 15th August (monsoon period), 2014. The mean mass concentration of BC was 4.03 (±0.85) μg m-3 with a daily variability between 2.4 and 5.64 μg m-3, however, the mean mass PM concentrations [near ultrafine (PM1.0), fine (PM2.5) and inhalable (PM10)] were 29.1(±16.2), 34.7 (±19.9) and 43.7 (±28.3) μg m-3, respectively. The contribution of BC in PM1.0 was approximately 13%, which is one of the highest being recorded. Diurnally, the BC mass concentrations were highest (mean: 5.89 μg m-3) between 20:00 to 22:00 local time (LT) due to the burning of biofuels/biomass such as wood, dung, straw and crop residue mixed with dung by the local residents for cooking purposes. The atmospheric direct radiative forcing values due to the composite and BC aerosols were determined to be +78.3, +44.9, and +45.0 W m-2 and +42.2, +35.4 and +34.3 W m-2 during the months of June, July and August, respectively. The corresponding atmospheric heating rates (AHR) for composite and BC aerosols were 2.21, 1.26 and 1.26; and 1.19, 0.99 and 0.96 K day-1 for the month of June, July and August, respectively, with a mean of 1.57 and 1.05 K day-1 which was 33% lower AHR (BC) than for the composite particles during the study period. This high AHR underscores the importance of absorbing aerosols such as BC contributed by residential cooking using biofuels in India. Our study demonstrates the need for immediate, effective regulations and policies that mitigate the emission of BC particles from domestic cooking in rural areas of India. © 2016 Elsevier B.V."
"56919125400;6506528166;7102567936;","Forcings and feedbacks on convection in the 2010 Pakistan flood: Modeling extreme precipitation with interactive large-scale ascent",2016,"10.1002/2016MS000663","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978091982&doi=10.1002%2f2016MS000663&partnerID=40&md5=9d0725dd3e68d3cca778fc4b8fb0073f","Extratropical extreme precipitation events are usually associated with large-scale flow disturbances, strong ascent, and large latent heat release. The causal relationships between these factors are often not obvious, however, the roles of different physical processes in producing the extreme precipitation event can be difficult to disentangle. Here we examine the large-scale forcings and convective heating feedback in the precipitation events, which caused the 2010 Pakistan flood within the Column Quasi-Geostrophic framework. A cloud-revolving model (CRM) is forced with large-scale forcings (other than large-scale vertical motion) computed from the quasi-geostrophic omega equation using input data from a reanalysis data set, and the large-scale vertical motion is diagnosed interactively with the simulated convection. Numerical results show that the positive feedback of convective heating to large-scale dynamics is essential in amplifying the precipitation intensity to the observed values. Orographic lifting is the most important dynamic forcing in both events, while differential potential vorticity advection also contributes to the triggering of the first event. Horizontal moisture advection modulates the extreme events mainly by setting the environmental humidity, which modulates the amplitude of the convection's response to the dynamic forcings. When the CRM is replaced by either a single-column model (SCM) with parameterized convection or a dry model with a reduced effective static stability, the model results show substantial discrepancies compared with reanalysis data. The reasons for these discrepancies are examined, and the implications for global models and theoretical models are discussed. © 2016. The Authors."
"24376965000;36093966500;57189637020;56095414700;6505588595;","Mesoscale extreme rainfall events in West Africa: The cases of Niamey (Niger) and the Upper Ouémé Valley (Benin)",2016,"10.1016/j.wace.2016.05.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973577781&doi=10.1016%2fj.wace.2016.05.001&partnerID=40&md5=a751ca9856aefb52695354300f579285","In West Africa, a sharp decrease in rainfall has occurred in conjunction with an increase in flood damage since 1970. The material damage and loss of life resulting from floods highlights the undeniable vulnerability of populations to this threat and illustrates the importance of addressing the evolution of hazardous precipitation caused by intense rainstorms. This work aims to improve our knowledge of the behaviour of extreme rainfall in West Africa by studying the sub-hourly, hourly and daily evolution of the most extreme rainfall events, a topic that is especially important to those interested in studying the links between heavy rainfall and flash flooding or inundation. This study analyses the classes of extreme rainfall events in two distinct climatic areas within West Africa using the meteorological scales relevant to rainfall processes. The study is based on two precipitation datasets recorded by dense networks of rain gauges set up within the meso-sites of Niamey (Niger, Sahelian area) and the Upper Ouémé Valley (Northern Benin, Soudanian zone) from 2000 to 2010 and 1998 to 2010, respectively. The Gumbel distribution was used to analyse the frequency of the maximum rainfall series for durations varying from 5 min to 24 h. The reliability of this model was examined, and the Intensity-Density-Frequency (IDF) curves derived from it were used to estimate the critical rainfall intensities at each site. The results returned exceeded frequencies that were useful for the isolation and classification of extreme rainfall cases using temporal characteristics. The climatological results confirm the existence of a latitudinal gradient in the mean annual rainfall and number of extreme events at the mesoscale. The classification methods illustrate clear distinctions between local, meso and synoptic scale events derived from convective systems over the Sahel. In contrast, Soudanian climate conditions lead to a nesting of the phenomena involved in the formation of cloud systems, making it difficult to classify rain events in that area. However, we were able to utilize the duration of rainfall events within this zone to discriminate between types of convective systems that cause extreme rainfall. For both areas, the proportion of precipitation in an extreme event compared to total yearly precipitation served as a suitable additional criterion used to objectively identify extreme precipitation event types. © 2016 The Authors"
"57111879700;7003510377;","Assessment of the weather research and forecasting model generalized parameterization schemes for advancement of precipitation forecasting in monsoon-driven river basins",2016,"10.1002/2016MS000678","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981537951&doi=10.1002%2f2016MS000678&partnerID=40&md5=cf5480e109b8f46eff480a5eb719a6ab","Some of the world's largest and flood-prone river basins experience a seasonal flood regime driven by the monsoon weather system. Highly populated river basins with extensive rain-fed agricultural productivity such as the Ganges, Indus, Brahmaputra, Irrawaddy, and Mekong are examples of monsoon-driven river basins. It is therefore appropriate to investigate how precipitation forecasts from numerical models can advance flood forecasting in these basins. In this study, the Weather Research and Forecasting model was used to evaluate downscaling of coarse-resolution global precipitation forecasts from a numerical weather prediction model. Sensitivity studies were conducted using the TOPSIS analysis to identify the likely best set of microphysics and cumulus parameterization schemes, and spatial resolution from a total set of 15 combinations. This identified best set can pinpoint specific parameterizations needing further development to advance flood forecasting in monsoon-dominated regimes. It was found that the Betts-Miller-Janjic cumulus parameterization scheme with WRF Single-Moment 5-class, WRF Single-Moment 6-class, and Thompson microphysics schemes exhibited the most skill in the Ganges-Brahmaputra-Meghna basins. Finer spatial resolution (3 km) without cumulus parameterization schemes did not yield significant improvements. The short-listed set of the likely best microphysics-cumulus parameterization configurations was found to also hold true for the Indus basin. The lesson learned from this study is that a common set of model parameterization and spatial resolution exists for monsoon-driven seasonal flood regimes at least in South Asian river basins. © 2016. The Authors."
"35345729700;16444949400;57208121047;16425152300;6603818654;6603848988;55718857500;27467537200;7003777747;6602414959;55702982900;11940188700;57202142004;6505805689;8388968100;10139397300;55545335600;7003489918;42662973900;6603478665;23485829700;6602600408;23968109800;57205638870;24390528000;57203180094;56151334000;23161713000;36021733300;","Multi-model evaluation of short-lived pollutant distributions over east Asia during summer 2008",2016,"10.5194/acp-16-10765-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984920622&doi=10.5194%2facp-16-10765-2016&partnerID=40&md5=0c4411a2aa9ec719d38bb94c196f1e0c","The ability of seven state-of-the-art chemistry-aerosol models to reproduce distributions of tropospheric ozone and its precursors, as well as aerosols over eastern Asia in summer 2008, is evaluated. The study focuses on the performance of models used to assess impacts of pollutants on climate and air quality as part of the EU ECLIPSE project. Models, run using the same ECLIPSE emissions, are compared over different spatial scales to in situ surface, vertical profiles and satellite data. Several rather clear biases are found between model results and observations, including overestimation of ozone at rural locations downwind of the main emission regions in China, as well as downwind over the Pacific. Several models produce too much ozone over polluted regions, which is then transported downwind. Analysis points to different factors related to the ability of models to simulate VOC-limited regimes over polluted regions and NO<i>x</i> limited regimes downwind. This may also be linked to biases compared to satellite NO2, indicating overestimation of NO2 over and to the north of the northern China Plain emission region. On the other hand, model NO2 is too low to the south and west of this region and over South Korea/Japan. Overestimation of ozone is linked to systematic underestimation of CO particularly at rural sites and downwind of the main Chinese emission regions. This is likely to be due to enhanced destruction of CO by OH. Overestimation of Asian ozone and its transport downwind implies that radiative forcing from this source may be overestimated. Model-observation discrepancies over Beijing do not appear to be due to emission controls linked to the Olympic Games in summer 2008.<br><br>With regard to aerosols, most models reproduce the satellite-derived AOD patterns over eastern China. Our study nevertheless reveals an overestimation of ECLIPSE model mean surface BC and sulphate aerosols in urban China in summer 2008. The effect of the short-term emission mitigation in Beijing is too weak to explain the differences between the models. Our results rather point to an overestimation of SO2 emissions, in particular, close to the surface in Chinese urban areas. However, we also identify a clear underestimation of aerosol concentrations over northern India, suggesting that the rapid recent growth of emissions in India, as well as their spatial extension, is underestimated in emission inventories. Model deficiencies in the representation of pollution accumulation due to the Indian monsoon may also be playing a role. Comparison with vertical aerosol lidar measurements highlights a general underestimation of scattering aerosols in the boundary layer associated with overestimation in the free troposphere pointing to modelled aerosol lifetimes that are too long. This is likely linked to too strong vertical transport and/or insufficient deposition efficiency during transport or export from the boundary layer, rather than chemical processing (in the case of sulphate aerosols). Underestimation of sulphate in the boundary layer implies potentially large errors in simulated aerosol-cloud interactions, via impacts on boundary-layer clouds.<br><br>This evaluation has important implications for accurate assessment of air pollutants on regional air quality and global climate based on global model calculations. Ideally, models should be run at higher resolution over source regions to better simulate urban-rural pollutant gradients and/or chemical regimes, and also to better resolve pollutant processing and loss by wet deposition as well as vertical transport. Discrepancies in vertical distributions require further quantification and improvement since these are a key factor in the determination of radiative forcing from short-lived pollutants."
"57190948518;8942525300;56757625500;6507564744;35810775100;8942524900;36659468200;36134816800;55831482700;12753162000;55683727600;55377690600;56377286600;","Impacts of aviation fuel sulfur content on climate and human health",2016,"10.5194/acp-16-10521-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984618875&doi=10.5194%2facp-16-10521-2016&partnerID=40&md5=c9d2c3a991433099038d1820ffb9dd9b","Aviation emissions impact both air quality and climate. Using a coupled tropospheric chemistry-aerosol microphysics model we investigate the effects of varying aviation fuel sulfur content (FSC) on premature mortality from long-term exposure to aviation-sourced PM2.5 (particulate matter with a dry diameter of &lt;2.5m) and on the global radiation budget due to changes in aerosol and tropospheric ozone. We estimate that present-day non-CO2 aviation emissions with a typical FSC of 600ppm result in ~3600 [95% CI: 1310-5890] annual premature mortalities globally due to increases in cases of cardiopulmonary disease and lung cancer, resulting from increased surface PM2.5 concentrations. We quantify the global annual mean combined radiative effect (REcomb) of non-CO2 aviation emissions as -13.3mWm-2 from increases in aerosols (direct radiative effect and cloud albedo effect) and tropospheric ozone. Ultra-low sulfur jet fuel (ULSJ; FSC Combining double low line15ppm) has been proposed as an option to reduce the adverse health impacts of aviation-induced PM2.5. We calculate that swapping the global aviation fleet to ULSJ fuel would reduce the global aviation-induced mortality rate by ~620 [95% CI: 230-1020] mortalitiesa-1 and increase REcomb by +7.0mWm-2.&lt;br&gt;&lt;br&gt; We explore the impact of varying aviation FSC between 0 and 6000ppm. Increasing FSC increases aviation-induced mortality, while enhancing climate cooling through increasing the aerosol cloud albedo effect (CAE). We explore the relationship between the injection altitude of aviation emissions and the resulting climate and air quality impacts. Compared to the standard aviation emissions distribution, releasing aviation emissions at the ground increases global aviation-induced mortality and produces a net warming effect, primarily through a reduced CAE. Aviation emissions injected at the surface are 5 times less effective at forming cloud condensation nuclei, reducing the aviation-induced CAE by a factor of 10. Applying high FSCs at aviation cruise altitudes combined with ULSJ fuel at lower altitudes results in reduced aviation-induced mortality and increased negative RE compared to the baseline aviation scenario. © Author(s) 2016. CC Attribution 3.0 License."
"7004690545;55827003100;7201502185;15841319100;7006577693;8877858700;7601491332;","The impact of changing the land surface scheme in ACCESS(v1.0/1.1) on the surface climatology",2016,"10.5194/gmd-9-2771-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983541147&doi=10.5194%2fgmd-9-2771-2016&partnerID=40&md5=03e9e544aca1ad3d762c146d1de1679e","The Community Atmosphere Biosphere Land Exchange (CABLE) model has been coupled to the UK Met Office Unified Model (UM) within the existing framework of the Australian Community Climate and Earth System Simulator (ACCESS), replacing the Met Office Surface Exchange Scheme (MOSES). Here we investigate how features of the CABLE model impact on present-day surface climate using ACCESS atmosphere-only simulations. The main differences attributed to CABLE include a warmer winter and a cooler summer in the Northern Hemisphere (NH), earlier NH spring runoff from snowmelt, and smaller seasonal and diurnal temperature ranges. The cooler NH summer temperatures in canopy-covered regions are more consistent with observations and are attributed to two factors. Firstly, CABLE accounts for aerodynamic and radiative interactions between the canopy and the ground below; this placement of the canopy above the ground eliminates the need for a separate bare ground tile in canopy-covered areas. Secondly, CABLE simulates larger evapotranspiration fluxes and a slightly larger daytime cloud cover fraction. Warmer NH winter temperatures result from the parameterization of cold climate processes in CABLE in snow-covered areas. In particular, prognostic snow density increases through the winter and lowers the diurnally resolved snow albedo; variable snow thermal conductivity prevents early winter heat loss but allows more heat to enter the ground as the snow season progresses; liquid precipitation freezing within the snowpack delays the building of the snowpack in autumn and accelerates snow melting in spring. Overall we find that the ACCESS simulation of surface air temperature benefits from the specific representation of the turbulent transport within and just above the canopy in the roughness sublayer as well as the more complex snow scheme in CABLE relative to MOSES. © 2016 Author(s)."
"55342873700;36473023300;56217494900;17433541700;9233141100;12801073500;6506718750;6603701937;57197038621;","HDO and H2O total column retrievals from TROPOMI shortwave infrared measurements",2016,"10.5194/amt-9-3921-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983544036&doi=10.5194%2famt-9-3921-2016&partnerID=40&md5=e1ccf06248163ce4f40e936aed387025","The TROPOspheric Monitoring Instrument (TROPOMI) on board the European Space Agency Sentinel-5 Precursor mission is scheduled for launch in the last quarter of 2016. As part of its operational processing the mission will provide CH4 and CO total columns using backscattered sunlight in the shortwave infrared band (2.3 μm). By adapting the CO retrieval algorithm, we have developed a non-scattering algorithm to retrieve total column HDO and H2O from the same measurements under clear-sky conditions. The isotopologue ratio HDO/H2O is a powerful diagnostic in the efforts to improve our understanding of the hydrological cycle and its role in climate change, as it provides an insight into the source and transport history of water vapour, nature's strongest greenhouse gas. Due to the weak reflectivity over water surfaces, we need to restrict the retrieval to cloud-free scenes over land. We exploit a novel 2-band filter technique, using strong vs. weak water or methane absorption bands, to prefilter scenes with medium-to-high-level clouds, cirrus or aerosol and to significantly reduce processing time. Scenes with cloud top heights ≲ 1km, very low fractions of high-level clouds or an aerosol layer above a high surface albedo are not filtered out. We use an ensemble of realistic measurement simulations for various conditions to show the efficiency of the cloud filter and to quantify the performance of the retrieval. The single-measurement precision in terms of D is better than 15-25‰ for even the lowest surface albedo (2-4‰ for high albedos), while a small bias remains possible of up to ∼ 20‰ due to remaining aerosol or up to ∼ 70‰ due to remaining cloud contamination. We also present an analysis of the sensitivity towards prior assumptions, which shows that the retrieval has a small but significant sensitivity to the a priori assumption of the atmospheric trace gas profiles. Averaging multiple measurements over time and space, however, will reduce these errors, due to the quasi-random nature of the profile uncertainties. The sensitivity of the retrieval with respect to instrumental parameters within the expected instrument performance is &lt; 3 ‰, which represents only a small contribution to the overall error budget. Spectroscopic uncertainties of the water lines, however, can have a larger and more systematic impact on the performance of the retrieval and warrant further reassessment of the water line parameters. With TROPOMI's high radiometric sensitivity, wide swath (resulting in daily global coverage) and efficient cloud filtering, in combination with a spatial resolution of 7×7 km2, we will greatly increase the amount of useful data on HDO, H2O and their ratio HDO=H2O. We showcase the overall performance of the retrieval algorithm and cloud filter with an accurate simulation of TROPOMI measurements from a single overpass over parts of the USA and Mexico, based on MODIS satellite data and realistic conditions for the surface, atmosphere and chemistry (including isotopologues). This shows that TROPOMI will pave the way for new studies of the hydrological cycle, both globally and locally, on timescales of mere days and weeks instead of seasons and years and will greatly extend the HDO=H2O datasets from the SCIAMACHY and GOSAT missions. © 2016 Author(s)."
"55865424100;55295927500;16642666900;55918454100;36134816800;6701620591;26638618800;15519671300;17433905200;55972194100;6602914876;26024789300;7006712143;56472932500;6701574983;57190860473;9235235300;","Implementation of state-of-the-art ternary new-particle formation scheme to the regional chemical transport model PMCAMx-UF in Europe",2016,"10.5194/gmd-9-2741-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983543828&doi=10.5194%2fgmd-9-2741-2016&partnerID=40&md5=657d46a752a78332c88386dcb996143f","The particle formation scheme within PMCAMx-UF, a three-dimensional chemical transport model, was updated with particle formation rates for the ternary H2SO4-NH3-H2O pathway simulated by the Atmospheric Cluster Dynamics Code (ACDC) using quantum chemical input data. The model was applied over Europe for May 2008, during which the EUCAARI-LONGREX (European Aerosol Cloud Climate and Air Quality Interactions-Long-Range Experiment) campaign was carried out, providing aircraft vertical profiles of aerosol number concentrations. The updated model reproduces the observed number concentrations of particles larger than 4ĝ€nm within 1 order of magnitude throughout the atmospheric column. This agreement is encouraging considering the fact that no semi-empirical fitting was needed to obtain realistic particle formation rates. The cloud adjustment scheme for modifying the photolysis rate profiles within PMCAMx-UF was also updated with the TUV (Tropospheric Ultraviolet and Visible) radiative-transfer model. Results show that, although the effect of the new cloud adjustment scheme on total number concentrations is small, enhanced new-particle formation is predicted near cloudy regions. This is due to the enhanced radiation above and in the vicinity of the clouds, which in turn leads to higher production of sulfuric acid. The sensitivity of the results to including emissions from natural sources is also discussed. © Author(s) 2016."
"7401709972;7102218643;35220988500;7101614616;55772718800;","New method and error analysis of lake retrieval with MetOp-A AVHRR images on the Tibetan Plateau",2016,"10.1080/01431161.2016.1199062","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978800301&doi=10.1080%2f01431161.2016.1199062&partnerID=40&md5=b6cdfcabb06eb9e99f28415f28ede95a","Land-surface water is an important factor influencing the regional environment and climate and is a key factor in the Tibetan Plateau, which is one of the most sensitive regions to global changes. Because of the high elevation, complex topography, and erratic weather of the Tibetan Plateau, direct measurement of the area of every lake is largely unfeasible. Moreover, complex natural geographic conditions increase the difficulty of image processing and information extraction with remote sensing because they enhance the uncertainty of quantitative data retrieved with satellites. Methods based on spectral features do not generate the expected results of lake area over the Tibetan Plateau due to a lack of distinction between water and other land objects, especially snow, vegetation, and low cloud cover. Therefore, a new method to extract lake area from satellite images in the Tibetan Plateau is needed. In this article, an automatic method was proposed to evaluate lake area during the wet season (from 1 September to 31 October) on the Tibetan Plateau with multi-day Advanced Very High Resolution Radiometer (AVHRR) remote-sensing images on board the Meteorological Operational satellite-A (MetOp-A) satellite. The method considers both spectral and textural features of lakes and does not need a cloud mask as an input. In addition, the Mixture Tuned Matched Filtering (MTMF) algorithm was applied to decompose the mixed pixels to better identify lakes and estimate the lake area. Based on daily lake identifications, the wet season’s lake data were composited with the maximum value composition (MVC) method to determine the lake area. A comparison of our work with the manually interpreted results from Landsat Thematic Mapper (TM) images and observational reports demonstrates the accuracy and reliability of our approach. However, certain factors, i.e. the sensor zenith angle of the polar-orbit satellite and the topography, can affect the lake area extracted from the remote-sensing images. © 2016 Informa UK Limited, trading as Taylor & Francis Group."
"55574869900;15051249600;23028245500;56898396100;","An improved iterative fitting method to estimate nocturnal residual layer height",2016,"10.3390/atmos7080106","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983744653&doi=10.3390%2fatmos7080106&partnerID=40&md5=5210784c2d7d1c29e04983a4d7decfc6","The planetary boundary layer (PBL) is an atmospheric region near the Earth's surface. It is significant for weather forecasting and for the study of air quality and climate. In this study, the top of nocturnal residual layers-which are what remain of the daytime mixing layer-are estimated by an elastic backscatter Lidar in Wuhan (30.5°N, 114.4°E), a city in Central China. The ideal profile fitting method is widely applied to determine the nocturnal residual layer height (RLH) from Lidar data. However, the method is seriously affected by an optical thick layer. Thus, we propose an improved iterative fitting method to eliminate the optical thick layer effect on RLH detection using Lidar. Two typical case studies observed by elastic Lidar are presented to demonstrate the theory and advantage of the proposed method. Results of case analysis indicate that the improved method is more practical and precise than profile-fitting, gradient, and wavelet covariance transform method in terms of nocturnal RLH evaluation under low cloud conditions. Long-term observations of RLH performed with ideal profile fitting and improved methods were carried out in Wuhan from 28 May 2011 to 17 June 2016. Comparisons of Lidar-derived RLHs with the two types of methods verify that the improved solution is practical. Statistical analysis of a six-year Lidar signal was conducted to reveal the monthly average values of nocturnal RLH inWuhan. A clear RLH monthly cycle with a maximum mean height of about 1.8 km above ground level was observed in August, and a minimum height of about 0.7 km was observed in January. The variation in monthly mean RLH displays an obvious quarterly dependence, which coincides with the annual variation in local surface temperature."
"56692405300;57209597073;","Atlantic Multidecadal Variability in a model with an improved North Atlantic Current",2016,"10.1002/2016GL069815","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982933573&doi=10.1002%2f2016GL069815&partnerID=40&md5=4838b8f1ad0cd0df17ee25cd786b5ad6","We examine the simulated Atlantic Multidecadal Variability (AMV) in a model that includes a correction for a long-standing problem with climate models, namely, the misplacement of the North Atlantic Current. The corrected model shows that in the warm AMV phase, heat is lost by the ocean in the northwestern part of the basin and gained by the ocean to the east, suggesting an advective transfer of heat by the midlatitude westerlies. The basin-wide response is consistent with a role for cloud feedback and is in broad agreement with estimates from observations but is poorly represented in the uncorrected model. The corrected model is then used to show that the ocean/atmosphere heat transfer is influenced by low-frequency variability in the overlying atmosphere. We also argue that changing ocean heat transport is an essential feature of our results. ©2016. American Geophysical Union. All Rights Reserved."
"57191034805;56384704800;55705948900;14019100300;","Revisiting the climate impacts of cool roofs around the globe using an Earth system model",2016,"10.1088/1748-9326/11/8/084014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84985996120&doi=10.1088%2f1748-9326%2f11%2f8%2f084014&partnerID=40&md5=31a00b8fad3558ee06c3586ac2633fb6","Solar reflective 'cool roofs' absorb less sunlight than traditional dark roofs, reducing solar heat gain, and decreasing the amount of heat transferred to the atmosphere. Widespread adoption of cool roofs could therefore reduce temperatures in urban areas, partially mitigating the urban heat island effect, and contributing to reversing the local impacts of global climate change. The impacts of cool roofs on global climate remain debated by past research and are uncertain. Using a sophisticated Earth system model, the impacts of cool roofs on climate are investigated at urban, continental, and global scales. We find that global adoption of cool roofs in urban areas reduces urban heat islands everywhere, with an annual- and global-mean decrease from 1.6 to 1.2 K. Decreases are statistically significant, except for some areas in Africa and Mexico where urban fraction is low, and some high-latitude areas during wintertime. Analysis of the surface and TOA energy budget in urban regions at continental-scale shows cool roofs causing increases in solar radiation leaving the Earth-atmosphere system in most regions around the globe, though the presence of aerosols and clouds are found to partially offset increases in upward radiation. Aerosols dampen cool roof-induced increases in upward solar radiation, ranging from 4% in the United States to 18% in more polluted China. Adoption of cool roofs also causes statistically significant reductions in surface air temperatures in urbanized regions of China (-0.11 ±0.10 K) and the United States (-0.14 ±0.12 K); India and Europe show statistically insignificant changes. Though past research has disagreed on whether widespread adoption of cool roofs would cool or warm global climate, these studies have lacked analysis on the statistical significance of global temperature changes. The research presented here indicates that adoption of cool roofs around the globe would lead to statistically insignificant reductions in global mean air temperature (-0.0021 ±0.026 K). Thus, we suggest that while cool roofs are an effective tool for reducing building energy use in hot climates, urban heat islands, and regional air temperatures, their influence on global climate is likely negligible. © 2016 IOP Publishing Ltd."
"36163267400;7102890924;15047403600;6602334969;7006304904;7004713805;7004539828;","Distribution of sulfur aerosol precursors in the SPCZ released by continuous volcanic degassing at Ambrym, Vanuatu",2016,"10.1016/j.jvolgeores.2015.07.018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994501736&doi=10.1016%2fj.jvolgeores.2015.07.018&partnerID=40&md5=ddd5f80b626ea9334147671300ad4d1a","The Melanesian Volcanic Arc (MVA) emits about 12 kT d− 1 of sulfur dioxide (SO2) to the atmosphere from continuous passive (non-explosive) volcanic degassing, which contributes 20% of the global SO2 emission from volcanoes. Here we assess, from up-to-date and long-term observations, the SO2 emission of the Ambrym volcano, one of the dominant volcanoes in the MVA, and we investigate its role as sulfate precursor on the regional distribution of aerosols, using both satellite observations and model results at 1° × 1° spatial resolution from WRF-Chem/GOCART. Without considering aerosol forcing on clouds, our model parameterizations for convection, vertical mixing and cloud properties provide a reliable chemical weather representation, making possible a cross-examination of model solution and observations. This preliminary work enables the identification of biases and limitations affecting both the model (missing sources) and satellite sensors and algorithms (for aerosol detection and classification) and leads to the implementation of improved transport and aerosol processes in the modeling system. On the one hand, the model confirms a 50% underestimation of SO2 emissions due to satellite swath sampling of the Ozone Monitoring Instrument (OMI), consistent with field studies. The OMI irregular sampling also produces a level of noise that impairs its monitoring capacity during short-term volcanic events. On the other hand, the model reveals a large sensitivity on aerosol composition and Aerosol Optical Depth (AOD) due to choices of both the source function in WRF-Chem and size parameters for sea-salt in FlexAOD, the post-processor used to compute offline the simulated AOD. We then proceed to diagnosing the role of SO2 volcanic emission in the regional aerosol composition. The model shows that both dynamics and cloud properties associated with the South Pacific Convergence Zone (SPCZ) have a large influence on the oxidation of SO2 and on the transport pathways of volcanic species across the South Pacific atmosphere. For example, in the tropical cloudy air, the sulfate production in the aqueous phase is very efficient, resulting in the formation of a large cloud of highly scattering sulfate aerosols advected horizontally to Eastern Indonesia, in agreement with the AOD feature captured by MODIS/Aqua, but missed in CALIOP/CALIPSO (lidar) products. Model sensitivity experiments indicate that aerosol re-suspension due to evaporating droplets is a significant pathway for the supply of volcanic sulfur species in the remote marine boundary layer. By strongly modulating the irreversible loss due to wet scavenging, this aerosol process has a similar influence on the sulfur burden as natural emission from volcanoes or biogenic sources like dimethyl sulfate (DMS). The results emphasize the importance of MVA passive degassing and SPCZ dynamics on the aerosol background, and raise questions about potential impacts on the local climate and marine ecosystems. © 2015 Elsevier B.V."
"57193840197;57203774491;6506180220;8934029200;24329545900;","Significant cooling effect on the surface due to soot particles over Brahmaputra River Valley region, India: An impact on regional climate",2016,"10.1016/j.scitotenv.2016.03.157","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963799421&doi=10.1016%2fj.scitotenv.2016.03.157&partnerID=40&md5=b4fad3078e12e60be5561dd394302cdc","Black carbon (BC) is an important atmospheric aerosol constituent that affects the climate by absorbing (directly) the sunlight and modifying cloud characteristics (indirectly). Here, we present first time yearlong measurements of BC and carbon monoxide (CO) from an urban location of Guwahati located in the Brahmaputra River valley (BRV) in the northeast region of India from 1st July 2013 to 30th June 2014. Daily BC concentrations varied within the range of 2.86 to 11.56 μg m-3 with an annual average of 7.17 ± 1.89 μg m-3, while, CO varied from 0.19 to 1.20 ppm with a mean value of 0.51 ± 0.19 ppm during the study period. The concentrations of BC (8.37 μg m-3) and CO (0.67 ppm) were ~39% and ~55% higher during the dry months (October to March) than the wet months (April to September) suggesting that seasonal changes in meteorology and emission sources play an important role in controlling these species. The seasonal δBC/δCO ratios were highest (lowest) in the pre-monsoon (winter) 18.1 ± 1.4 μg m-3 ppmv-1 (12.6 ± 2.2 μg m-3 ppmv-1) which indicate the combustion of biofuel/biomass as well as direct emissions from fossil fuel during the pre-monsoon season. The annual BC emission was estimated to be 2.72 Gg in and around Guwahati which is about 44% lower than the mega city 'Delhi' (4.86 Gg). During the study period, the annual mean radiative forcing (RF) at the top of the atmosphere (TOA) for clear skies of BC was +9.5 Wm-2, however, the RF value at the surface (SFC) was -21.1 Wm-2 which indicates the net warming and cooling effects, respectively. The highest RF at SFC was in the month of April (-30 Wm-2) which is coincident with the highest BC mass level. The BC atmospheric radiative forcing (ARF) was +30.16 (annual mean) Wm-2 varying from +23.1 to +43.8 Wm-2. The annual mean atmospheric heating rate (AHR) due to the BC aerosols was 0.86 K day-1 indicates the enhancement in radiation effect over the study region. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) captured the seasonal cycle of observed BC fairly well but underestimated the observed BC during the month of May-August. Model results show that BC at Guwahati is controlled mainly by anthropogenic emissions except during the pre-monsoon season when open biomass burning also makes a similar contribution. © 2016 Elsevier B.V."
"55808550300;35106150700;55944537900;55567285700;56735478500;7005742190;","Atmospheric salt deposition in a tropical mountain rainforest at the eastern Andean slopes of south Ecuador-Pacific or Atlantic origin?",2016,"10.5194/acp-16-10241-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982152477&doi=10.5194%2facp-16-10241-2016&partnerID=40&md5=0ae9bc5f84170c81730727e9df48ad9a","Sea salt (NaCl) has recently been proven to be of the utmost importance for ecosystem functioning in Amazon lowland forests because of its impact on herbivory, litter decomposition and, thus, carbon cycling. Sea salt deposition should generally decline as distance from its marine source increases. For the Amazon, a negative east-west gradient of sea salt availability is assumed as a consequence of the barrier effect of the Andes Mountains for Pacific air masses. However, this generalized pattern may not hold for the tropical mountain rainforest in the Andes of southern Ecuador. To analyse sea salt availability, we investigated the deposition of sodium (Na+) and chloride (Cl-), which are good proxies of sea spray aerosol. Because of the complexity of the terrain and related cloud and rain formation processes, sea salt deposition was analysed from both, rain and occult precipitation (OP) along an altitudinal gradient over a period between 2004 and 2009. To assess the influence of easterly and westerly air masses on the deposition of sodium and chloride over southern Ecuador, sea salt aerosol concentration data from the Monitoring Atmospheric Composition and Climate (MACC) reanalysis data set and back-trajectory statistical methods were combined. Our results, based on deposition time series, show a clear difference in the temporal variation of sodium and chloride concentration and Na+Cl- ratio in relation to height and exposure to winds. At higher elevations, sodium and chloride present a higher seasonality and the Na+Cl- ratio is closer to that of sea salt. Medium-to long-range sea salt transport exhibited a similar seasonality, which shows the link between our measurements at high elevations and the sea salt synoptic transport. Although the influence of the easterlies was predominant regarding the atmospheric circulation, the statistical analysis of trajectories and hybrid receptor models revealed a stronger impact of the north equatorial Atlantic, Caribbean, and Pacific sea salt sources on the atmospheric sea salt concentration in southern Ecuador. The highest concentration in rain and cloud water was found between September and February when air masses originated from the north equatorial Atlantic, the Caribbean Sea and the equatorial Pacific. Together, these sources accounted for around 82.4% of the sea salt budget over southern Ecuador. © 2016 Author(s)."
"36904222100;7402859325;","Seasonal variation of nitrate concentration and its direct radiative forcing over East Asia",2016,"10.3390/atmos7080105","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983749195&doi=10.3390%2fatmos7080105&partnerID=40&md5=b6b35bd9dea353e08e26599b1d1e0716","This study investigated the seasonal variation of nitrate concentration and its radiative forcing over East Asia by using an online-coupled regional climate model. Comparison with a series of in-situ observations from Acid Deposition Monitoring Network in East Asia (EANET) and China demonstrated a good skill of the model in reproducing the magnitude and seasonality of nitrate concentration across East Asia. It was found that nitrate concentration in Beijing and Tianjin exhibited the maximum in summer and the minimum in winter possibly due to stronger chemical oxidation and regional transport effect of larger emissions from the north China Plain in summer, whereas in most areas of East Asia, nitrate concentration was higher in winter and lower in summer, consistent with the seasonality of NOx emission. Surface nitrate concentration was higher over the lower reaches of the Yellow River, followed by the middle to lower reaches of the Yangtze River and portions of south China, and lower in Korean Peninsula and Japan. The annual mean surface nitrate concentration was predicted to be 2.9 μg·m-3 for East Asia and 8.5 μg·m-3 for east China. All-sky direct radiative forcing (DRF) due to nitrate at the top of the atmosphere (TOA) exhibited the largest forcing up to -7W·m-2 over the lower reaches of the Yellow River, and lower forcing of ~-2W·m-2 in the Korean Peninsula and Japan. Clear-sky DRF by nitrate reached the maximum in spring and the minimum in summer over both East Asia and east China, whereas DRF under all-sky condition showed its maximum in autumn, associated with seasonalities of nitrate column burden, relative humidity, and cloud effect. Annual mean all-sky DRFs at TOA were estimated to be -1.7 W·m-2 and -3.7 W·m-2 over East Asia and east China, respectively, significantly larger than global annual mean, suggesting the important role of nitrate aerosol in environment and climate change over East Asia."
"12144198300;37087012900;6701729202;","Toward autonomous surface-based infrared remote sensing of polar clouds: Cloud-height retrievals",2016,"10.5194/amt-9-3641-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981541484&doi=10.5194%2famt-9-3641-2016&partnerID=40&md5=4dd4df1af7cb314f8a93ec6b24730dc9","Polar regions are characterized by their remoteness, making measurements challenging, but an improved knowledge of clouds and radiation is necessary to understand polar climate change. Infrared radiance spectrometers can operate continuously from the surface and have low power requirements relative to active sensors. Here we explore the feasibility of retrieving cloud height with an infrared spectrometer that would be designed for use in remote polar locations. Using a wide variety of simulated spectra of mixed-phase polar clouds at varying instrument resolutions, retrieval accuracy is explored using the CO2 slicing/sorting and the minimum local emissivity variance (MLEV) methods. In the absence of imposed errors and for clouds with optical depths greater than ∼0.3, cloud-height retrievals from simulated spectra using CO2 slicing/sorting and MLEV are found to have roughly equivalent high accuracies: at an instrument resolution of 0.5 cm-1, mean biases are found to be ∼0.2 km for clouds with bases below 2 and-0.2 km for higher clouds. Accuracy is found to decrease with coarsening resolution and become worse overall for MLEV than for CO2 slicing/sorting; however, the two methods have differing sensitivity to different sources of error, suggesting an approach that combines them. For expected errors in the atmospheric state as well as both instrument noise and bias of 0.2 mW/(m2 sr cm-1), at a resolution of 4 cm-1, average retrieval errors are found to be less than ∼0.5 km for cloud bases within 1 km of the surface, increasing to ∼1.5 km at 4 km. This sensitivity indicates that a portable, surface-based infrared radiance spectrometer could provide an important complement in remote locations to satellite-based measurements, for which retrievals of low-level cloud are challenging. © 2016 Author(s)."
"7003341789;36921601500;8791306500;55479763800;7404247296;7005453641;8856938500;56499447000;","A multi-wavelength classification method for polar stratospheric cloud types using infrared limb spectra",2016,"10.5194/amt-9-3619-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981489074&doi=10.5194%2famt-9-3619-2016&partnerID=40&md5=032618f1ff9c50a7ea534547d84f224e","The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument on board the ESA Envisat satellite operated from July 2002 until April 2012. The infrared limb emission measurements represent a unique dataset of daytime and night-time observations of polar stratospheric clouds (PSCs) up to both poles. Cloud detection sensitivity is comparable to space-borne lidars, and it is possible to classify different cloud types from the spectral measurements in different atmospheric windows regions. Here we present a new infrared PSC classification scheme based on the combination of a well-established two-colour ratio method and multiple 2-D brightness temperature difference probability density functions. The method is a simple probabilistic classifier based on Bayes' theorem with a strong independence assumption. The method has been tested in conjunction with a database of radiative transfer model calculations of realistic PSC particle size distributions, geometries, and composition. The Bayesian classifier distinguishes between solid particles of ice and nitric acid trihydrate (NAT), as well as liquid droplets of super-cooled ternary solution (STS). The classification results are compared to coincident measurements from the space-borne lidar Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument over the temporal overlap of both satellite missions (June 2006-March 2012). Both datasets show a good agreement for the specific PSC classes, although the viewing geometries and the vertical and horizontal resolution are quite different. Discrepancies are observed between the CALIOP and the MIPAS ice class. The Bayesian classifier for MIPAS identifies substantially more ice clouds in the Southern Hemisphere polar vortex than CALIOP. This disagreement is attributed in part to the difference in the sensitivity on mixed-type clouds. Ice seems to dominate the spectral behaviour in the limb infrared spectra and may cause an overestimation in ice occurrence compared to the real fraction of ice within the PSC area in the polar vortex. The entire MIPAS measurement period was processed with the new classification approach. Examples like the detection of the Antarctic NAT belt during early winter, and its possible link to mountain wave events over the Antarctic Peninsula, which are observed by the Atmospheric Infrared Sounder (AIRS) instrument, highlight the importance of a climatology of 9 Southern Hemisphere and 10 Northern Hemisphere winters in total. The new dataset is valuable both for detailed process studies, and for comparisons with and improvements of the PSC parameterizations used in chemistry transport and climate models. © 2016 Author(s)."
"56151545200;7102010848;56672215300;56997768500;57204481655;56539258900;8438057200;55687369200;7006495018;56162305900;55917306900;7401967617;7402803216;","Effects of aerosol-radiation interaction on precipitation during biomass-burning season in East China",2016,"10.5194/acp-16-10063-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981723060&doi=10.5194%2facp-16-10063-2016&partnerID=40&md5=648447db71653acdfcc8ee4f3656b99c","Biomass burning is a main source for primary carbonaceous particles in the atmosphere and acts as a crucial factor that alters Earth's energy budget and balance. It is also an important factor influencing air quality, regional climate and sustainability in the domain of Pan-Eurasian Experiment (PEEX). During the exceptionally intense agricultural fire season in mid-June 2012, accompanied by rapidly deteriorating air quality, a series of meteorological anomalies was observed, including a large decline in near-surface air temperature, spatial shifts and changes in precipitation in Jiangsu province of East China. To explore the underlying processes that link air pollution to weather modification, we conducted a numerical study with parallel simulations using the fully coupled meteorology-chemistry model WRF-Chem with a high-resolution emission inventory for agricultural fires. Evaluation of the modeling results with available ground-based measurements and satellite retrievals showed that this model was able to reproduce the magnitude and spatial variations of fire-induced air pollution. During the biomass-burning event in mid-June 2012, intensive emission of absorbing aerosols trapped a considerable part of solar radiation in the atmosphere and reduced incident radiation reaching the surface on a regional scale, followed by lowered surface sensible and latent heat fluxes. The perturbed energy balance and re-allocation gave rise to substantial adjustments in vertical temperature stratification, namely surface cooling and upper-air heating. Furthermore, an intimate link between temperature profile and small-scale processes like turbulent mixing and entrainment led to distinct changes in precipitation. On the one hand, by stabilizing the atmosphere below and reducing the surface flux, black carbon-laden plumes tended to dissipate daytime cloud and suppress the convective precipitation over Nanjing. On the other hand, heating aloft increased upper-level convective activity and then favored convergence carrying in moist air, thereby enhancing the nocturnal precipitation in the downwind areas of the biomass-burning plumes. © 2016 Author(s)."
"55813627900;8953662800;55153585300;56610914500;57213521610;13407966600;55543826100;","Planetary boundary layer height from CALIOP compared to radiosonde over China",2016,"10.5194/acp-16-9951-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981340997&doi=10.5194%2facp-16-9951-2016&partnerID=40&md5=9e526e0bfaa10327e071aa285a9b98f5","Accurate estimation of planetary boundary layer height (PBLH) is key to air quality prediction, weather forecast, and assessment of regional climate change. The PBLH retrieval from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) is expected to complement ground-based measurements due to the broad spatial coverage of satellites. In this study, CALIOP PBLHs are derived from combination of Haar wavelet and maximum variance techniques, and are further validated against PBLHs estimated from ground-based lidar at Beijing and Jinhua. Correlation coefficients between PBLHs from ground-and satellite-based lidars are 0.59 at Beijing and 0.65 at Jinhua. Also, the PBLH climatology from CALIOP and radiosonde are compiled over China during the period from 2011 to 2014. Maximum CALIOP-derived PBLH can be seen in summer as compared to lower values in other seasons. Three matchup scenarios are proposed according to the position of each radiosonde site relative to its closest CALIPSO ground tracks. For each scenario, intercomparisons were performed between CALIOP-and radiosonde-derived PBLHs, and scenario 2 is found to be better than other scenarios using difference as the criteria. In early summer afternoon over 70% of the total radiosonde sites have PBLH values ranging from 1.6 to 2.0km. Overall, CALIOP-derived PBLHs are well consistent with radiosonde-derived PBLHs. To our knowledge, this study is the first intercomparison of PBLH on a large scale using the radiosonde network of China, shedding important light on the data quality of initial CALIOP-derived PBLH results. © 2016 Author(s)."
"57189524073;22986631300;7102976560;7004214645;10139397300;12240390300;6507308842;","Regional and global temperature response to anthropogenic SO2 emissions from China in three climate models",2016,"10.5194/acp-16-9785-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982812266&doi=10.5194%2facp-16-9785-2016&partnerID=40&md5=f96f5c3bb0fe0337d801687cc1c89a32","We use the HadGEM3-GA4, CESM1, and GISS ModelE2 climate models to investigate the global and regional aerosol burden, radiative flux, and surface temperature responses to removing anthropogenic sulfur dioxide (SO2) emissions from China. We find that the models differ by up to a factor of 6 in the simulated change in aerosol optical depth (AOD) and shortwave radiative flux over China that results from reduced sulfate aerosol, leading to a large range of magnitudes in the regional and global temperature responses. Two of the three models simulate a near-ubiquitous hemispheric warming due to the regional SO2 removal, with similarities in the local and remote pattern of response, but overall with a substantially different magnitude. The third model simulates almost no significant temperature response. We attribute the discrepancies in the response to a combination of substantial differences in the chemical conversion of SO2 to sulfate, translation of sulfate mass into AOD, cloud radiative interactions, and differences in the radiative forcing efficiency of sulfate aerosol in the models. The model with the strongest response (HadGEM3-GA4) compares best with observations of AOD regionally, however the other two models compare similarly (albeit poorly) and still disagree substantially in their simulated climate response, indicating that total AOD observations are far from sufficient to determine which model response is more plausible. Our results highlight that there remains a large uncertainty in the representation of both aerosol chemistry as well as direct and indirect aerosol radiative effects in current climate models, and reinforces that caution must be applied when interpreting the results of modelling studies of aerosol influences on climate. Model studies that implicate aerosols in climate responses should ideally explore a range of radiative forcing strengths representative of this uncertainty, in addition to thoroughly evaluating the models used against observations. © The Author(s) 2016."
"8576496400;56919576300;55683878900;7006790175;22834248200;57208046776;57195257572;7102603429;24537168200;7006837187;7004864963;6603172418;","Biogenic cloud nuclei in the central Amazon during the transition from wet to dry season",2016,"10.5194/acp-16-9727-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982684562&doi=10.5194%2facp-16-9727-2016&partnerID=40&md5=61fb4056b374bf0b9ec426ef0d38fe2b","The Amazon basin is a vast continental area in which atmospheric composition is relatively unaffected by anthropogenic aerosol particles. Understanding the properties of the natural biogenic aerosol particles over the Amazon rainforest is key to understanding their influence on regional and global climate. While there have been a number of studies during the wet season, and of biomass burning particles in the dry season, there has been relatively little work on the transition period-the start of the dry season in the absence of biomass burning. As part of the Brazil-UK Network for Investigation of Amazonian Atmospheric Composition and Impacts on Climate (BUNIAACIC) project, aerosol measurements, focussing on unpolluted biogenic air masses, were conducted at a remote rainforest site in the central Amazon during the transition from wet to dry season in July 2013. This period marks the start of the dry season but before significant biomass burning occurs in the region. Median particle number concentrations were 266 cm-3, with size distributions dominated by an accumulation mode of 130-150 nm. During periods of low particle counts, a smaller Aitken mode could also be seen around 80 nm. While the concentrations were similar in magnitude to those seen during the wet season, the size distributions suggest an enhancement in the accumulation mode compared to the wet season, but not yet to the extent seen later in the dry season, when significant biomass burning takes place. Submicron nonrefractory aerosol composition, as measured by an aerosol chemical speciation monitor (ACSM), was dominated by organic material (around 81 %). Aerosol hygroscopicitywas probed using measurements from a hygroscopicity tandem differential mobility analyser (HTDMA), and a quasi-monodisperse cloud condensation nuclei counter (CCNc). The hygroscopicity parameter, κ, was found to be low, ranging from 0.12 for Aitken-mode particles to 0.18 for accumulation-mode particles. This was consistent with previous studies in the region, but lower than similar measurements conducted in Borneo, where κ ranged 0.17-0.37. A wide issue bioaerosol sensor (WIBS-3M) was deployed at ground level to probe the coarse mode, detecting primary biological aerosol by fluorescence (fluorescent biological aerosol particles, or FBAPs). The mean FBAP number concentration was 400±242 L-1; however, this ranged from around 200 L-1 during the day to as much as 1200 L-1 at night. FBAPs dominated the coarse-mode particles, comprising between 55 and 75% of particles during the day to more than 90% at night. Non-FBAPs did not show a strong diurnal pattern. Comparison with previous FBAP measurements above canopy at the same location suggests there is a strong vertical gradient in FBAP concentrations through the canopy. Cluster analysis of the data suggests that FBAPs were dominated (around 70%) by fungal spores. Further, long-term measurements will be required in order to fully examine the seasonal variability and distribution of primary biological aerosol particles through the canopy. This is the first time that such a suite of measurements has been deployed at this site to investigate the chemical composition and properties of the biogenic contributions to Amazonian aerosol during the transition period from the wet to the dry season, and thus provides a unique comparison to the aerosol properties observed during the wet season in previous similar campaigns. This was also the first deployment of a WIBS in the Amazon rainforest to study coarse-mode particles, particularly primary biological aerosol particles, which are likely to play an important role as ice nuclei in the region. © 2016 Author(s)."
"56091801700;55872205000;7406294260;57205877879;14519510100;","Improving LAI spatio-temporal continuity using a combination of MODIS and MERSI data",2016,"10.1080/2150704X.2016.1182657","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975893290&doi=10.1080%2f2150704X.2016.1182657&partnerID=40&md5=76488fa00a6fe9608cb4129bc7e8f133","Spatio-temporally continuous leaf area index (LAI) is required for surface process simulation, climate modelling and global change study. As a result of cloud contamination and other factors, the current LAI products are spatially and temporally discontinuous. A multi-sensor integration method was proposed in this paper to combine Terra-Moderate Resolution Imaging Spectroradiometer (MODIS), Aqua-MODIS, FY (FengYun) 3A-MEdium Resolution Spectrum Imager (MERSI) and FY3B-MERSI data to improve LAI spatio-temporal continuity. It consists of a normalization algorithm to eliminate the difference between MODIS and MERSI data in spatial and spectral aspects, a daily LAI retrieval algorithm based on neural networks and a maximum value compositing algorithm. The feasibility of our LAI retrieval method to improve continuity was assessed at national scale (in China). Results show that (1) the combination of multi-sensor data can significantly improve LAI temporal continuity, especially for mountainous regions which are characterized by high frequency of cloud coverage; (2) the improvement in spatial continuity is obvious as can be seen from the increase of retrieval ratio, defined as the ratio of the number of retrieved pixels to the total number of pixels, from 0.78 for GEOV1 LAI product, and 0.88 for MOD15A2 LAI product to 0.98 for multi-sensor LAI product. © 2016 Informa UK Limited, trading as Taylor & Francis Group."
"56647601700;7402270526;21743348300;23011853200;56421781300;8953662800;8976516100;57195198884;36815906900;56381381600;57190729384;","Technical note: Intercomparison of three AATSR Level 2 (L2) AOD products over China",2016,"10.5194/acp-16-9655-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982719258&doi=10.5194%2facp-16-9655-2016&partnerID=40&md5=a3126e8a5c2966f518dd0a02b135b69c","One of four main focus areas of the PEEX initiative is to establish and sustain long-term, continuous, and comprehensive ground-based, airborne, and seaborne observation infrastructure together with satellite data. The Advanced Along-Track Scanning Radiometer (AATSR) aboard ENVISAT is used to observe the Earth in dual view. The AATSR data can be used to retrieve aerosol optical depth (AOD) over both land and ocean, which is an important parameter in the characterization of aerosol properties. In recent years, aerosol retrieval algorithms have been developed both over land and ocean, taking advantage of the features of dual view, which can help eliminate the contribution of Earth's surface to top-of-atmosphere (TOA) reflectance. The Aerosol-cci project, as a part of the Climate Change Initiative (CCI), provides users with three AOD retrieval algorithms for AATSR data, including the Swansea algorithm (SU), the ATSR-2ATSR dual-view aerosol retrieval algorithm (ADV), and the Oxford-RAL Retrieval of Aerosol and Cloud algorithm (ORAC). The validation team of the Aerosol-CCI project has validated AOD (both Level 2 and Level 3 products) and AE (Ångström Exponent) (Level 2 product only) against the AERONET data in a round-robin evaluation using the validation tool of the AeroCOM (Aerosol Comparison between Observations and Models) project. For the purpose of evaluating different performances of these three algorithms in calculating AODs over mainland China, we introduce ground-based data from CARSNET (China Aerosol Remote Sensing Network), which was designed for aerosol observations in China. Because China is vast in territory and has great differences in terms of land surfaces, the combination of the AERONET and CARSNET data can validate the L2 AOD products more comprehensively. The validation results show different performances of these products in 2007, 2008, and 2010. The SU algorithm performs very well over sites with different surface conditions in mainland China from March to October, but it slightly underestimates AOD over barren or sparsely vegetated surfaces in western China, with mean bias error (MBE) ranging from 0.05 to 0.10. The ADV product has the same precision with a low root mean square error (RMSE) smaller than 0.2 over most sites and the same error distribution as the SU product. The main limits of the ADV algorithm are underestimation and applicability; underestimation is particularly obvious over the sites of Datong, Lanzhou, and Urumchi, where the dominant land cover is grassland, with an MBE larger than 0.2, and the main aerosol sources are coal combustion and dust. The ORAC algorithm has the ability to retrieve AOD at different ranges, including high AOD (larger than 1.0); however, the stability deceases significantly with increasing AOD, especially when AOD>1.0. In addition, the ORAC product is consistent with the CARSNET product in winter (December, January, and February), whereas other validation results lack matches during winter. © Author(s) 2016."
"55462884000;36538539800;7004046707;7006461606;","Changes in future air quality, deposition, and aerosol-cloud interactions under future climate and emission scenarios",2016,"10.1016/j.atmosenv.2016.05.008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976649872&doi=10.1016%2fj.atmosenv.2016.05.008&partnerID=40&md5=bf979edcf316b5e36874f128b3c6132b","The prospect of global climate change will have wide scale impacts, such as ecological stress and human health hazards. One aspect of concern is future changes in air quality that will result from changes in both meteorological forcing and air pollutant emissions. In this study, the GU-WRF/Chem model is employed to simulate the impact of changing climate and emissions following the IPCC AR4 SRES A1B scenario. An average of 4 future years (2020, 2030, 2040, and 2050) is compared against an average of 2 current years (2001 and 2010). Under this scenario, by the Mid-21st century global air quality is projected to degrade with a global average increase of 2.5 ppb in the maximum 8-hr O3 level and of 0.3 μg m-3 in 24-hr average PM2.5. However, PM2.5 changes are more regional due to regional variations in primary aerosol emissions and emissions of gaseous precursor for secondary PM2.5. Increasing NOx emissions in this scenario combines with a wetter climate elevating levels of OH, HO2, H2O2, and the nitrate radical and increasing the atmosphere's near surface oxidation state. This differs from findings under the RCP scenarios that experience declines in OH from reduced NOx emissions, stratospheric recovery of O3, and increases in CH4 and VOCs. Increasing NOx and O3 levels enhances the nitrogen and O3 deposition, indicating potentially enhanced crop damage and ecosystem stress under this scenario. The enhanced global aerosol level results in enhancements in aerosol optical depth, cloud droplet number concentration, and cloud optical thickness. This leads to dimming at the Earth's surface with a global average reduction in shortwave radiation of 1.2 W m-2. This enhanced dimming leads to a more moderate warming trend and different trends in radiation than those found in NCAR's CCSM simulation, which does not include the advanced chemistry and aerosol treatment of GU-WRF/Chem and cannot simulate the impacts of changing climate and emissions with the same level of detailed treatments. This study indicates that effective climate mitigation and emission control strategies are needed to prevent future health impact and ecosystem stress. Further, studies that are used to develop these strategies should use fully coupled models with sophisticated chemical and aerosol-interaction treatments that can provide a more realistic representation of the atmosphere. © 2016 Elsevier Ltd."
"55366637500;7004714030;6603925960;6505465237;30667558200;","Use of A-train satellite observations (CALIPSO–PARASOL) to evaluate tropical cloud properties in the LMDZ5 GCM",2016,"10.1007/s00382-015-2900-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84946771449&doi=10.1007%2fs00382-015-2900-y&partnerID=40&md5=bd47f5504d5b6bff250e5007567d2228","The evaluation of key cloud properties such as cloud cover, vertical profile and optical depth as well as the analysis of their intercorrelation lead to greater confidence in climate change projections. In addition, the comparison between observations and parameterizations of clouds in climate models is improved by using collocated and instantaneous data of cloud properties. Simultaneous and independent observations of the cloud cover and its three-dimensional structure at high spatial and temporal resolutions are made possible by the new space-borne multi-instruments observations collected with the A-train. The cloud cover and its vertical structure observed by CALIPSO and the visible directional reflectance (a surrogate for the cloud optical depth) observed by PARASOL, are used to evaluate the representation of cloudiness in two versions of the atmospheric component of the IPSL-CM5 climate model (LMDZ5). A model-to-satellite approach, applying the CFMIP Observation Simulation Package (COSP), is used to allow a quantitative comparison between model results and observations. The representation of clouds in the two model versions is first evaluated using monthly mean data. This classical approach reveals biases of different magnitudes in the two model versions. These biases consist of (1) an underestimation of cloud cover associated to an overestimation of cloud optical depth, (2) an underestimation of low- and mid-level tropical clouds and (3) an overestimation of high clouds. The difference in the magnitude of these biases between the two model versions clearly highlights the improvement of the amount of boundary layer clouds, the improvement of the properties of high-level clouds, and the improvement of the simulated mid-level clouds in the tropics in LMDZ5B compared to LMDZ5A, due to the new convective, boundary layer, and cloud parametrizations implemented in LMDZ5B. The correlation between instantaneous cloud properties allows for a process-oriented evaluation of tropical oceanic clouds. This process-oriented evaluation shows that the cloud population characterized by intermediate values of cloud cover and cloud reflectance can be split in two groups of clouds when using monthly mean values of cloud cover and cloud reflectance: one group with low to intermediate values of the cloud cover, and one group with cloud cover close to one. The precise determination of cloud height allows us to focus on specific types of clouds (i.e. boundary layer clouds, high clouds, low-level clouds with no clouds above). For low-level clouds over the tropical oceans, the relationship between instantaneous values of the cloud cover and of the cloud reflectance reveals a major bias in the simulated liquid water content for both model versions. The origin of this bias is identified and possible improvements, such as considering the sub-grid heterogeneity of cloud properties, are investigated using sensitivity experiments. In summary, the analysis of the relationship between different instantaneous and collocated variables allows for process-oriented evaluations. These evaluations may in turn help to improve model parameterizations, and may also help to bridge the gap between model evaluation and model development. © 2016, Springer-Verlag Berlin Heidelberg."
"7003444634;57126848900;22635999400;7203034123;56767841200;35547214900;8627503500;6602407753;57208765879;7202727242;","Polarized view of supercooled liquid water clouds",2016,"10.1016/j.rse.2016.04.002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963877334&doi=10.1016%2fj.rse.2016.04.002&partnerID=40&md5=27fc97e8b17c867d5703b314b2499ae5","Supercooled liquid water (SLW) clouds, where liquid droplets exist at temperatures below 0°C present a well-known aviation hazard through aircraft icing, in which SLW accretes on the airframe. SLW clouds are common over the Southern Ocean, and climate-induced changes in their occurrence is thought to constitute a strong cloud feedback on global climate. The two recent NASA field campaigns POlarimeter Definition EXperiment (PODEX, based in Palmdale, California, January-February 2013) and Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS, based in Houston, Texas in August-September 2013) provided a unique opportunity to observe SLW clouds from the high-altitude airborne platform of NASA's ER-2 aircraft. We present an analysis of measurements made by the Research Scanning Polarimeter (RSP) during these experiments accompanied by correlative retrievals from other sensors. The RSP measures both polarized and total reflectance in 9 spectral channels with wavelengths ranging from 410 to 2250 nm. It is a scanning sensor taking samples at 0.8° intervals within 60° from nadir in both forward and backward directions. This unique angular resolution allows for characterization of liquid water droplet size using the rainbow structure observed in the polarized reflectances in the scattering angle range between 135° and 165°. Simple parametric fitting algorithms applied to the polarized reflectance provide retrievals of the droplet effective radius and variance assuming a prescribed size distribution shape (gamma distribution). In addition to this, we use a non-parametric method, Rainbow Fourier Transform (RFT), which allows retrieval of the droplet size distribution without assuming a size distribution shape. We present an overview of the RSP campaign datasets available from the NASA GISS website, as well as two detailed examples of the retrievals. In these case studies we focus on cloud fields with spatial features varying between glaciated and liquid phases at altitudes as high as 10 km, which correspond to temperatures close to the homogeneous freezing temperature of pure water drops (about -35°C or colder). The multimodal droplet size distributions retrieved from RSP data in these cases are consistent with the multi-layer cloud structure observed by correlative Cloud Physics Lidar (CPL) measurements. © 2016 Elsevier Inc."
"7102922928;22942281200;6602390261;57053353500;7005515085;55805082800;57204253860;55796091800;","Proportions of convective and stratiform precipitation revealed in water isotope ratios",2016,"10.1038/ngeo2739","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84980328096&doi=10.1038%2fngeo2739&partnerID=40&md5=66083e3424588cb9349ce8574efebce1","Tropical and midlatitude precipitation is fundamentally of two types, spatially limited and high-intensity convective or widespread and lower-intensity stratiform, owing to differences in vertical air motions and microphysical processes governing rain formation. These processes are difficult to observe or model and precipitation partitioning into rain types is critical for understanding how the water cycle responds to changes in climate. Here, we combine two independent data sets - convective and stratiform precipitation fractions, derived from the Tropical Rainfall Measuring Mission satellite or synoptic cloud observations, and stable isotope and tritium compositions of surface precipitation, derived from a global network - to show that isotope ratios reflect rain type proportions and are negatively correlated with stratiform fractions. Condensation and riming associated with boundary layer moisture produces higher isotope ratios in convective rain, along with higher tritium when riming in deep convection occurs with entrained air at higher altitudes. On the basis of our data, stable isotope ratios can be used to monitor changes in the character of precipitation in response to periodic variability or changes in climate. Our results also provide observational constraints for an improved simulation of convection in climate models and a better understanding of isotope variations in proxy archives, such as speleothems and tropical ice. © 2016 Macmillan Publishers Limited. All rights reserved."
"56543788800;8550791300;57189470543;55555084100;7201352328;7003459101;7403200489;7006415284;18536452000;","On the usage of classical nucleation theory in quantification of the impact of bacterial INP on weather and climate",2016,"10.1016/j.atmosenv.2016.05.034","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971222345&doi=10.1016%2fj.atmosenv.2016.05.034&partnerID=40&md5=5ed04cc217cd726a71d6a520b167fb0e","Bacterial ice-nucleating particles (INP) are present in the atmosphere and efficient in heterogeneous ice-nucleation at temperatures up to -2 °C in mixed-phase clouds. However, due to their low emission rates, their climatic impact was considered insignificant in previous modeling studies. In view of uncertainties about the actual atmospheric emission rates and concentrations of bacterial INP, it is important to re-investigate the threshold fraction of cloud droplets containing bacterial INP for a pronounced effect on ice-nucleation, by using a suitable parameterization that describes the ice-nucleation process by bacterial INP properly. Therefore, we compared two heterogeneous ice-nucleation rate parameterizations, denoted CH08 and HOO10 herein, both of which are based on classical-nucleation-theory and measurements, and use similar equations, but different parameters, to an empirical parameterization, denoted HAR13 herein, which considers implicitly the number of bacterial INP. All parameterizations were used to calculate the ice-nucleation probability offline. HAR13 and HOO10 were implemented and tested in a one-dimensional version of a weather-forecast-model in two meteorological cases. Ice-nucleation-probabilities based on HAR13 and CH08 were similar, in spite of their different derivation, and were higher than those based on HOO10. This study shows the importance of the method of parameterization and of the input variable, number of bacterial INP, for accurately assessing their role in meteorological and climatic processes. © 2016 Elsevier Ltd."
"56539196700;57205872550;","Dust induced changes in ice cloud and cloud radiative forcing over a high altitude site",2016,"10.4209/aaqr.2015.05.0325","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979944498&doi=10.4209%2faaqr.2015.05.0325&partnerID=40&md5=957fc51473a3dc493adf443ea453b2c9","Aerosol-cloud interaction is the subject of considerable scientific research, due to the importance of clouds in controlling climate. In the present study, three years (2011-2013) satellite observations are used to investigate the aerosol indirect effect (AIE) over Dehradun. The low values of Angstrom exponent (α) during March-July are attributed to the loading of dust-like coarse particles in the atmosphere, whereas the analysis of aerosol type and Spectral Radiation Transport Model for Aerosol species (SPRINTARS) simulated aerosol species variation supports the fact. Moderate Resolution Imaging Spectroradiometer (MODIS) derived AOD data are associated to the cloud product to examine the dust impact on properties of liquid cloud and ice cloud. The positive values of aerosol cloud interaction effect (ACI) for ice cloud during pre-monsoon (March-May) and monsoon (June-August) seasons reveal the significant impact of dust on ice clouds over Dehradun, which is maximum during May (~0.24 ± 0.05). The present study shows that ice cloud effective radius (ICER) decrease with AOD during dust period. The increase in ice water path (IWP) and ice cloud optical depth (ICOD) reveals the impact of dust on heterogeneous ice generation in low level clouds. However, there is no relation between dust and liquid water cloud during dust period. It is difficult to provide definite conclusions that the dust and cloud changes are driven by the same meteorological conditions. Cloud and the Earth’s Radiant Energy System (CERES) derived flux data are used to examine the associated changes in TOA cloud radiative forcing. The diminution in effective size of ice crystal due to aerosol first indirect effect traps more longwave radiation and reflects more solar radiation. Both first and second indirect effects enhance cloud cooling, whereas the dust induced cloud warming is mainly the result of the semi-direct effect. © Taiwan Association for Aerosol Research."
"55958422800;55228409700;7403077486;57203348817;","Aerosol impacts on thermally driven orographic convection",2016,"10.1175/JAS-D-15-0320.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982291464&doi=10.1175%2fJAS-D-15-0320.1&partnerID=40&md5=394bcc2cbc0a7d87cde4759caafa44bb","Observations from the Dominica Experiment (DOMEX) field campaign clearly show aerosols having an impact on cloud microphysical properties in thermally driven orographic clouds. It is hypothesized that when convection is forced by island surface heating, aerosols from the mostly forested island surface are lofted into the clouds, resulting in the observed high concentration of aerosols and the high concentration of small cloud droplets. When trying to understand the impact of these surface-based aerosols on precipitation, however, observed differences in cloud-layer moisture add to the complexity. The WRF Model with the aerosol-aware Thompson microphysics scheme is used to study six idealized scenarios of thermally driven island convection: with and without a surface aerosol source, with a relatively dry cloud layer and with a moist cloud layer, and with no wind and with a weak background wind. It is found that at least a weak background wind is needed to ensure Dominica-relevant results and that the effect of cloud-layer moisture on cloud and precipitation formation dominates over the effect of aerosol. The aerosol impact is limited by the dominance of precipitation formation through accretion. Nevertheless, in order to match observed cloud microphysical properties and precipitation, both a relatively dry cloud layer and a surface aerosol source are needed. The impact of a surface aerosol source on precipitation is strongest when the environment is not conducive to cloud growth. © 2016 American Meteorological Society."
"52564166000;6602699701;6602729528;8571302000;","Influence of atmospheric circulation patterns on local cloud and solar variability in Bergen, Norway",2016,"10.1007/s00704-015-1517-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84931864143&doi=10.1007%2fs00704-015-1517-8&partnerID=40&md5=73f6b1af194b4dfaee987564cc237f9c","In a previous paper, we have shown that long-term cloud and solar observations (1965–2013) in Bergen, Norway (60.39°N, 5.33°E) are compatible with a largely cloud dominated radiative climate. Here, we explicitly address the relationship between the large scale circulation over Europe and local conditions in Bergen, identifying specific circulation shifts that have contributed to the observed cloud and solar variations. As a measure of synoptic weather patterns, we use the Grosswetterlagen (GWL), a daily classification of European weather for 1881–2013. Empirical models of cloud cover, cloud base, relative sunshine duration, and normalised global irradiance are constructed based on the GWL frequencies, extending the observational time series by more than 70 years. The GWL models successfully reproduce the observed increase in cloud cover and decrease in solar irradiance during the 1970s and 1980s. This cloud-induced dimming is traced to an increasing frequency of cyclonic and decreasing frequency of anticyclonic weather patterns over northern Europe. The changing circulation patterns in winter can be understood as a shift from the negative to the positive phase of the North Atlantic and Arctic Oscillation. A recent period of increasing solar irradiance is observed but not reproduce by the GWL models, suggesting this brightening is associated with factors other than large scale atmospheric circulation, possibly decreasing aerosol loads and local cloud shifts. © 2015, Springer-Verlag Wien."
"36598281300;55667384900;36627288300;35769583500;55883034700;6603618077;24921885300;16403388800;","Assessing the habitability of planets with Earth-like atmospheres with 1D and 3D climate modeling",2016,"10.1051/0004-6361/201628413","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978880079&doi=10.1051%2f0004-6361%2f201628413&partnerID=40&md5=d00b669281617e009749fbb8499c13cb","Context. The habitable zone (HZ) describes the range of orbital distances around a star where the existence of liquid water on the surface of an Earth-like planet is in principle possible. The applicability of one-dimensional (1D) climate models for the estimation of the HZ boundaries has been questioned by recent three-dimensional (3D) climate studies. While 3D studies can calculate the water vapor, ice albedo, and cloud feedback self-consistently and therefore allow for a deeper understanding and the identification of relevant climate processes, 1D model studies rely on fewer model assumptions and can be more easily applied to the large parameter space possible for extrasolar planets. Aims. We evaluate the applicability of 1D climate models to estimate the potential habitability of Earth-like extrasolar planets by comparing our 1D model results to those of 3D climate studies in the literature. We vary the two important planetary properties, surface albedo and relative humidity, in the 1D model. These depend on climate feedbacks that are not treated self-consistently in most 1D models. Methods. We applied a cloud-free 1D radiative-convective climate model to calculate the climate of Earth-like planets around different types of main-sequence stars with varying surface albedo and relative humidity profile. We compared the results to those of 3D model calculations available in the literature and investigated to what extent the 1D model can approximate the surface temperatures calculated by the 3D models. Results. The 1D parameter study results in a large range of climates possible for an Earth-sized planet with an Earth-like atmosphere and water reservoir at a certain stellar insolation. At some stellar insolations the full spectrum of climate states could be realized, i.e., uninhabitable conditions due to surface temperatures that are too high or too low as well as habitable surface conditions, depending only on the relative humidity and surface albedo assumed. When treating the surface albedo and the relative humidity profile as parameters in 1D model studies and using the habitability constraints found by recent 3D modeling studies, the same conclusions about the potential habitability of a planet can be drawn as from 3D model calculations. © 2016 ESO."
"7007088807;23988450000;","CMSAF products Cloud Fraction Coverage and Cloud Type used for solar global irradiance estimation",2016,"10.1007/s00703-015-0424-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955589371&doi=10.1007%2fs00703-015-0424-y&partnerID=40&md5=dcf3db6f61ee2f405e46cc85a120f6d5","Two products provided by the climate monitoring satellite application facility (CMSAF) are the instantaneous Cloud Fractional Coverage (iCFC) and the instantaneous Cloud Type (iCTY) products. Previous studies based on the iCFC product show that the simple solar radiation models belonging to the cloudiness index class nCFC = 0.1–1.0 have rRMSE values ranging between 68 and 71 %. The products iCFC and iCTY are used here to develop simple models providing hourly estimates for solar global irradiance. Measurements performed at five weather stations of Romania (South-Eastern Europe) are used. Two three-class characterizations of the state-of-the-sky, based on the iCTY product, are defined. In case of the first new sky state classification, which is roughly related with cloud altitude, the solar radiation models proposed here perform worst for the iCTY class 4–15, with rRMSE values ranging between 46 and 57 %. The spreading error of the simple models is lower than that of the MAGIC model for the iCTY classes 1–4 and 15–19, but larger for iCTY classes 4–15. In case of the second new sky state classification, which takes into account in a weighted manner the chance for the sun to be covered by different types of clouds, the solar radiation models proposed here perform worst for the cloudiness index class nCTY = 0.7–0.1, with rRMSE values ranging between 51 and 66 %. Therefore, the two new sky state classifications based on the iCTY product are useful in increasing the accuracy of solar radiation models. © 2016, Springer-Verlag Wien."
"54382826700;37101378500;7407663749;","Precipitation over urban areas in the western Maritime Continent using a convection-permitting model",2016,"10.1007/s00382-015-2893-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84946114670&doi=10.1007%2fs00382-015-2893-6&partnerID=40&md5=6e50fee43b4d3f5131c1b84ced748959","This study investigates the effects of urban areas on precipitation in the western Maritime Continent using a convection-permitting regional atmospheric model. The Weather Research and Forecasting model was used to simulate the atmosphere at a range of spatial resolutions using a multiple nesting approach. Two experiments (with and without urban areas) were completed over a 5-year period (2008–2012) each to estimate the contribution of cities to changes in local circulation. At first, the model is evaluated against two satellite-derived precipitation products and the benefit of using a very high-resolution model (2-km grid spacing) over a region where rainfall is dominated by convective processes is demonstrated, particularly in terms of its diurnal cycle phase and amplitude. The influence of cities on precipitation characteristics is quantified for two major urban nuclei in the region (Jakarta and Kuala Lumpur) and results indicate that their presence locally enhances precipitation by over 30 %. This increase is mainly due to an intensification of the diurnal cycle. We analyse the impact on temperature, humidity and wind to put forward physical mechanisms that explain such changes. Cities increase near surface temperature, generating instability. They also make land-sea temperature contrasts stronger, which enhances sea breeze circulations. Together, they increase near-surface moisture flux convergence and favour convective processes leading to an overall increase of precipitation over urban areas. The diurnal cycle of these effects is reflected in the atmospheric footprint of cities on variables such as humidity and cloud mixing ratio and accompanies changes in precipitation. © 2015, Springer-Verlag Berlin Heidelberg."
"10939346700;7004238125;","Application of a regional model to astronomical site testing in western Antarctica",2016,"10.1007/s00704-016-1794-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964311380&doi=10.1007%2fs00704-016-1794-x&partnerID=40&md5=a8671640e1f34e94ab39213f3a30987f","The quality of ground-based astronomical observations is significantly affected by local atmospheric conditions, and the search for the best sites has led to the construction of observatories at increasingly remote locations, including recent initiatives on the high plateaus of East Antarctica where the calm, dry, and cloud-free conditions during winter are recognized as amongst the best in the world. Site selection is an important phase of any observatory development project, and candidate sites must be tested in the field with specialized equipment, a process both time consuming and costly. A potential means of screening site locations before embarking on field testing is through the use of regional climate models (RCMs). In this study, we describe the application of the Polar version of the Weather Research and Forecasting (WRF) model to the preliminary site suitability assessment of a hitherto unstudied region in West Antarctica. Numerical simulations with WRF were carried out for the winter (MJJA) of 2011 at 3- and 1-km spatial resolution over a region centered on the Ellsworth mountain range. Comparison with observations of surface wind speed and direction, temperature, and specific humidity at nine automatic weather stations indicates that the model performed well in capturing the mean values and time variability of these variables. Credible features revealed by the model includes zones of high winds over the southernmost part of the Ellsworth Mountains, a deep thermal inversion over the Ronne-Fincher Ice Shelf, and strong west to east moisture gradient across the entire study area. Comparison of simulated cloud fraction with a CALIPSO spacebourne Lidar climatology indicates that the model may underestimate cloud occurrence, a problem that has been noted in previous studies. A simple scoring system was applied to reveal the most promising locations. The results of this study indicate that the WRF model is capable of providing useful guidance during the initial site selection stage of project development. © 2016, Springer-Verlag Wien."
"55935714300;16416660600;57188725544;","Aerosols loading trends and its environmental threats over Cotonou-Benin",2016,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-84986269244&partnerID=40&md5=b9fe05b665709f0a68c117737dbe6c92","Environmental security is totally relegated in countries of West Africa. The monitoring of the aerosols loading over Cotonou was the aim of this study. The outcome of our finding has salient links to food security, aviation and communication industry, thermal comfort and climate system of Benin. Cotonou is located on longitude 2.43°E and latitude 6.37°N. Fifteen years data were obtained from the multiangled spectro-reflectometry (MISR). The aerosol loading was monitored using analytical and statistical techniques. The aerosols retention over Cotonou was high in 2000 (69.91%), 2008 (72%) and 2013 (42.45%). This means that there is the possibility of higher rising sea levels and exposure to coastal erosion due to a twisted cloud formation."
"56278161100;26324818700;","Isolating the temperature feedback loop and its effects on surface temperature",2016,"10.1175/JAS-D-15-0287.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982262304&doi=10.1175%2fJAS-D-15-0287.1&partnerID=40&md5=cf73c1380721611284b50d8b4ee338b7","Climate feedback processes are known to substantially amplify the surface warming response to an increase of greenhouse gases. When the forcing and feedbacks modify the temperature response they trigger temperature feedback loops that amplify the direct temperature changes due to the forcing and nontemperature feedbacks through the thermal-radiative coupling between the atmosphere and surface. This study introduces a new feedback-response analysis method that can isolate and quantify the effects of the temperature feedback loops of individual processes on surface temperature from their corresponding direct surface temperature responses. The authors analyze a 1% yr-1 increase of CO2 simulation of the NCAR CCSM4 at the time of CO2 doubling to illustrate the new method. The Planck sensitivity parameter, which indicates colder regions experience stronger surface temperature responses given the same change in surface energy flux, is the inherent factor that leads to polar warming amplification (PWA). This effect explains the PWA in the Antarctic, while the direct temperature response to the albedo and cloud feedbacks further explains the greater PWA of the Arctic. Temperature feedback loops, particularly the one associated with the albedo feedback, further amplify the Arctic surface warming relative to the tropics. In the tropics, temperature feedback loops associated with the CO2 forcing and water vapor feedback cause most of the surface warming. Overall, the temperature feedback is responsible for most of the surface warming globally, accounting for nearly 76% of the global-mean surface warming. This is 3 times larger than the next largest warming contribution, indicating that the temperature feedback loop is the preeminent contributor to the surface warming. © 2016 American Meteorological Society."
"6507944872;55453202800;55263254000;54890778200;7203068499;7006173230;","Ice nucleation, shape, and composition of aerosol particles in one of the most polluted cities in the world: Ulaanbaatar, Mongolia",2016,"10.1016/j.atmosenv.2016.05.037","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971422897&doi=10.1016%2fj.atmosenv.2016.05.037&partnerID=40&md5=d2d89ee0b77c5781948c48cbc8a69841","Air pollution is attributable to 7 million deaths per year, or one out of every eight deaths globally. In particular, high concentrations of particulate matter (PM), a major air pollutant, have significant impacts on health and regional climate in urban centers. Many of the most polluted places, largely in developing countries, go severely understudied. Additionally, high particulate matter levels can have an impact on the microphysical properties of clouds, impacting precipitation and regional climate. Semi-arid regions can be especially affected by small changes in precipitation. Here we characterize the physical and chemical properties of PM in one of the most PM-polluted cities in the world: Ulaanbaatar, Mongolia, a semi-arid region in central Asia. Twice monthly aerosol samples were collected over 10 months from a central location and analyzed for composition and ice nucleation activity. Almost all particles collected were inhalable, consisting primarily of mineral dust, soot, and sulfate-organic. In winter, all classes of PM increase in concentration, with increased sulfur concentrations, and the particles are less active towards heterogeneous ice nucleation. In addition, concurrent monthly average PM10, SO2, NOx, and O3 levels and meteorological data at a nearby location are reported and made publicly available. These measurements provide an unprecedented seasonal characterization of the size, shape, chemical structure, and ice nucleating activity of PM data from Ulaanbaatar. This 10-month field study, exploring a variety of aerosol properties in Ulaanbaatar, Mongolia, is one of very few such studies conducted in the region or in such a highly polluted environment. The results of this study may inform work done in other similarly situated and polluted cities in Asia and elsewhere. © 2016 Elsevier Ltd."
"40462155100;6603885684;6507214754;24344797600;7005830802;7005868114;","Late Holocene vegetation and fire dynamics on the summits of the Guayana Highlands: The Uei-tepui palynological record",2016,"10.1016/j.palaeo.2016.05.008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966937506&doi=10.1016%2fj.palaeo.2016.05.008&partnerID=40&md5=cfd471f60ab12a18d7d426c6214b2af6","The summits of the tepuis (sandstone table mountains of the Neotropical Guayana region-Guayana Highlands, GH) have been considered valuable for palaeoecological studies due to their pristine nature, which emphasizes the role of natural (i.e. non-human) factors on ecological change. Anthropogenic fires, very frequent in the surrounding Gran Sabana (GS) uplands, have very rarely been documented in the GH, and are therefore not considered an important ecological factor in the high-tepui biome. This paper reports the palynological and charcoal results of a Late Holocene sequence from the summit of Uei-tepui (2104 m elevation), where extensive signs of fire were recently observed. Since ~. 2000 cal yr BP, the landscape of the study site has been dominated by meadows with occasional shrubs and cloud forests, which underwent expansions and contractions driven by climate changes and fire. A major vegetation shift occurred in the mid-18th century, when a sustained increase in local fires favoured the expansion of the low and spreading Cyrilla racemiflora shrublands at the expense of meadows and forests. Uei-tepui fires most probably were the result of human activities and reached the summit under study from the GS uplands through the vegetated slopes that characterize this tepui. The mostly anthropogenic nature of these fires, especially the more recent ones, is supported by the initial occurrence of wetter conditions, and by its coincidence with significant social changes in the GS indigenous populations, mainly the European contact. The emergence of fire as a disturbing agent of the GH biome highlights the need for an effective management plan in the GS uplands, where the vast majority of present-day fires originate, and designed in collaboration with the indigenous communities. Proactive conservation measures are considered even more important under future warming projections in the area. © 2016 Elsevier B.V.."
"6603555567;6701344406;56276813400;24479033900;26323963700;8915901800;","North Atlantic summer storm tracks over Europe dominated by internal variability over the past millennium",2016,"10.1038/ngeo2752","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84980329511&doi=10.1038%2fngeo2752&partnerID=40&md5=083925dbd07ae7efd99098db23f795bc","Certain large, sustained anomalies in European temperatures in the past millennium are probably the result of internal variation. Such internal variations can modulate regional temperatures away from the expected response to greenhouse gas forcing. Here we assess the causes of European summer temperature variability over the past millennium using temperature observations, simulations and reconstructions. We find multidecadal-mean summer temperatures have varied within a span of 1 K, largely controlled by external forcing. By contrast, we find subcontinental variations, described by the temperature contrast between northern and southern Europe (the meridional temperature gradient), vary with a span of 2 K, and are controlled by internal processes. These variations are the result of redistributions of precipitation and cloud cover linked to oscillations in the position of the summer storm track. In contrast to recent twentieth-century winter-time trends, variations of the summer storm track over the past millennium show a weak response to external forcing, and instead are dominated by stochastic internal variability. We argue that the response of European summer temperatures to anthropogenic greenhouse forcing is likely to be spatially modulated by the same stochastic internal processes that have caused periods of cool, wet summers in northern Europe over the last millennium. © 2016 Macmillan Publishers Limited. All rights reserved."
"6507781926;6507589406;6507013735;57203056321;8628779000;","Modern and fossil pollen assemblages reveal forest taxonomic changes in the Mexican subtropics during the last 1300years",2016,"10.1016/j.revpalbo.2016.04.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966293375&doi=10.1016%2fj.revpalbo.2016.04.007&partnerID=40&md5=8ee9800426a26b2bec01c8ed787379fd","The usual approach to reconstructing long-term vegetation dynamics is through the use of fossil pollen records from sedimentary sequences. This requires, however, an understanding of the relationship between modern pollen and the species composition and distribution on landscapes. Since different taxa produce different amounts of pollen, with different dispersal characteristics, understanding this relationship can be complex. This research aimed to address the following questions: Is it possible to distinguish different high-altitude forests by modern pollen signature? Is modern pollen abundance related to forest structure, forest diversity or to differences in altitude? How well can modern and fossil pollen assemblages reveal changes in the forest composition over the past ~. 1300. years?Data were collected on present-day forest composition and structure and diversity, paired with modern pollen samples in three high-altitude forest types: pine forest, cloud forest and a transitional forest (a mixture of Pinus-Quercus-Carpinus) in west-central Mexico. A sediment core was collected from each vegetation type for reconstructing past vegetation. Constrained and unconstrained ordination methods were used to discern patterns of variation and the correlates behind the datasets. To compare the fossil with the modern pollen assemblages, dissimilarity indexes were computed between each of the fossil pollen sequences and their modern assemblages at different altitudes using the chord distance.Results demonstrated that each of the three forests types was distinctive in composition, and modern and fossil pollen reflected local vegetation at stand level; mean diameter and altitude were the main variables related to differences among modern pollen signatures. When reconstructing high-altitude vegetation in the subtropics, it is important to consider all taxa, even if they are rare. Therefore, in order to reveal responses to climate change and human disturbances at stand level in forests at different successional stages; particularly from 102 to 104m2 and, at temporal scales from 102 to 103years, it is essential to combine modern and fossil pollen together with present-day vegetation records. © 2016 Elsevier B.V."
"57189226148;57197840312;9240820800;26653483100;","A Comparison of Tropical Rainforest Phenology Retrieved from Geostationary (SEVIRI) and Polar-Orbiting (MODIS) Sensors Across the Congo Basin",2016,"10.1109/TGRS.2016.2552462","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966271574&doi=10.1109%2fTGRS.2016.2552462&partnerID=40&md5=4a42e0bea5200b030deaa1cc73b2a599","The seasonal and interannual dynamics of tropical rainforests play a critical role in the global carbon cycle and climate change. This paper retrieved and compared land surface phenology from observations acquired by the Spinning Enhanced Visible and Infrared Imager (SEVIRI) onboard geostationary satellites and the Moderate Resolution Imaging Spectroradiometer (MODIS) on polar-orbiting satellites over the Congo Basin. To achieve this, we first retrieved canopy greenness cycles (CGCs) and their transition timing from two-band enhanced vegetation index (EVI2) derived from SEVIRI and MODIS data between 2006 and 2013. We then assessed the influences of SEVIRI and MODIS data quality on the reconstruction of the EVI2 temporal trajectory, the detection of the CGC onset and end timing, and the total number of successful CGC retrievals. The significance of influences was determined using the one-tailed two-sample Kolmogorov-Smirnov test. The results indicate that diurnal SEVIRI observations greatly increased the probability of capturing cloud-free daily EVI2 in the rainforest-dominated region of the Congo Basin, where the proportion of good quality (PGQ) observations during a CGC was up to 80% higher than that from MODIS. As a result, the double annual CGCs of the Congo Basin rainforests were well identified from SEVIRI but sparsely detected from MODIS, whereas the single annual CGC in the savanna-dominated northern and southern Congo Basin was successfully retrieved from both SEVIRI and MODIS. Moreover, the decreases of PGQ in an EVI2 time series were found to significantly increase the uncertainties of retrieved phenological timings and increase the probabilities of CGC retrieval failures. © 2016 IEEE."
"24475057200;23986836600;56714558200;7103050910;57190356296;50061738900;57069916800;","Estimation of monthly global solar irradiation using the Hargreaves–Samani model and an artificial neural network for the state of Alagoas in northeastern Brazil",2016,"10.1007/s00704-015-1541-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84936791575&doi=10.1007%2fs00704-015-1541-8&partnerID=40&md5=bba71ca49d83fec7a6d5555680e34498","The monthly global solar irradiation (Hg) was estimated using the Hargreaves–Samani model (HS) with three different approaches for determining the kr coefficient and using an artificial neural network (ANN). The data consisted of long-term climate series measured at eight conventional meteorological stations in the state of Alagoas and its borders in northeastern Brazil. The approaches to determine the kr coefficient of the HS model included (i) the method proposed by Hargreaves (1994) (0.190 and 0.162 for coastal and interior regions, respectively), (ii) a method analogous to the previous except with altitude correction, and (iii) kr fitted with local climatic data. A new spatial interpolation method is also proposed to determine kr as a function of geographical coordinates and altitude. The fitted local values of kr (0.168–0.179 and 0.189–0.231 for interior and coastal stations, respectively) exhibited a strong dependence (r2 = 0.81) on latitude, longitude, and altitude. The estimates of Hg obtained with the HS model using fitted local values of kr and those using the ANN were similar (determination coefficient - r2 = 0.75 and Willmontt agreement coefficient - d = 0.93) and better than those from the HS model using an altitude-corrected kr (r2 = 0.68 and d = 0.90) or the values proposed by Hargreaves (1994) (r2 = 0.57 and d = 0.85). The estimates of Hg were less accurate and precise for the coastal stations, where cloudiness and humidity are high and the thermal amplitude is small. © 2015, Springer-Verlag Wien."
"37010774300;24315205000;57193129591;25622793600;55923697700;15759638700;6701344406;","Changes in surface solar radiation in Northeastern Spain over the past six centuries recorded by tree-ring δ13C",2016,"10.1007/s00382-015-2881-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84947439999&doi=10.1007%2fs00382-015-2881-x&partnerID=40&md5=9030ba76d713657b7448b86a3e98810b","Although solar radiation at the surface plays a determinant role in carbon discrimination in tree rings, stable carbon isotope chronologies (δ13C) have often been interpreted as a temperature proxy due to the co-variability of temperature and surface solar radiation. Furthermore, even when surface solar radiation is assumed to be the main driver of 13C discrimination in tree rings, δ13C records have been calibrated against sunshine duration or cloud cover series for which longer observational records exists. In this study, we use different instrumental and satellite data over northeast Spain (southern Europe) to identify the main driver of tree-ring 13C discrimination in this region. Special attention is paid to periods in which the co-variability of those climate variables may have been weaker, such as years after large volcanic eruptions. The analysis identified surface solar radiation as the main driver of tree-ring δ13C changes in this region, although the influence of other climatic factors may not be negligible. Accordingly, we suggest that a reconstruction of SSR over the last 600 years is possible. The relation between multidecadal variations of an independent temperature reconstruction and surface solar radiation in this region shows no clear sign, and warmer (colder) periods may be accompanied by both higher and lower surface solar radiation. However, our reconstructed records of surface solar radiation reveals a sunnier Little Ice Age in agreement with other δ13C tree-ring series used to reconstruct sunshine duration in central and northern Europe. © 2015, Springer-Verlag Berlin Heidelberg."
"57190671825;36730825100;6507799089;55886290100;36131955000;57190667617;57203555934;57190664828;56868156600;57190666950;55317625500;57190666791;55787810700;57190673379;57190672553;36626171700;36926416100;7005140378;55950878200;7004590620;7004035832;","Examining variation in the leaf mass per area of dominant species across two contrasting tropical gradients in light of community assembly",2016,"10.1002/ece3.2281","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982145837&doi=10.1002%2fece3.2281&partnerID=40&md5=9e344584470c2c11726518c90967ddc8","Understanding variation in key functional traits across gradients in high diversity systems and the ecology of community changes along gradients in these systems is crucial in light of conservation and climate change. We examined inter- and intraspecific variation in leaf mass per area (LMA) of sun and shade leaves along a 3330-m elevation gradient in Peru, and in sun leaves across a forest–savanna vegetation gradient in Brazil. We also compared LMA variance ratios (T-statistics metrics) to null models to explore internal (i.e., abiotic) and environmental filtering on community structure along the gradients. Community-weighted LMA increased with decreasing forest cover in Brazil, likely due to increased light availability and water stress, and increased with elevation in Peru, consistent with the leaf economic spectrum strategy expected in colder, less productive environments. A very high species turnover was observed along both environmental gradients, and consequently, the first source of variation in LMA was species turnover. Variation in LMA at the genus or family levels was greater in Peru than in Brazil. Using dominant trees to examine possible filters on community assembly, we found that in Brazil, internal filtering was strongest in the forest, while environmental filtering was observed in the dry savanna. In Peru, internal filtering was observed along 80% of the gradient, perhaps due to variation in taxa or interspecific competition. Environmental filtering was observed at cloud zone edges and in lowlands, possibly due to water and nutrient availability, respectively. These results related to variation in LMA indicate that biodiversity in species rich tropical assemblages may be structured by differential niche-based processes. In the future, specific mechanisms generating these patterns of variation in leaf functional traits across tropical environmental gradients should be explored. © 2016 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd."
"55523304700;8413672100;6602283489;35755270400;55524267300;7004135527;57202425542;","Evaluation and application of hydrometeor classification algorithm outputs inferred from multi-frequency dual-polarimetric radar observations collected during HyMeX",2016,"10.1002/qj.2589","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983392876&doi=10.1002%2fqj.2589&partnerID=40&md5=90f14e2d547a7279b026e7c7bf822be7","A fuzzy logic hydrometeor classification algorithm (HCA), allowing discrimination between six microphysical species regardless of the radar wavelength is presented and evaluated. The proposed method is based upon combination sets of dual-polarimetric observables (reflectivity at horizontal polarization ZH, differential reflectivity ZDR, specific differential phase KDP, correlation coefficient ρHV) along with temperature data inferred from a numerical weather prediction model output. The performance of the HCA is evaluated using 20 h of multi-frequency dual-polarimetric radar data collected during the first Special Observation Period (SOP1) of the Hydrological Cycle in the Mediterranean Experiment (HyMeX). A new method based upon intercomparisons of retrieved hydrometeor data deduced from pairs of neighbouring radars (S-band vs. S-band and S-band vs. C-band) over a common sampling area is proposed to evaluate the consistency of hydrometor classification outputs. S-/C-band radar comparisons generally show better consistency than S-/S-band radar comparisons due to issues with the identification of the 0°C isotherm on one of the two S-band radars. Imperfect attenuation correction at C-band may also lead into differences in hydrometeor fields retrieved from the C- and S-band radars in convective situations, but retrieved hydrometeor data are globally very consistent from one radar to another. Comparisons against in situ airborne data also confirm the overall good performance of the HCA. In a second experiment, an original method allowing the production of multi-radar three-dimensional (3D) hydrometeor fields from single-radar 2D hydrometeor data is tested on a bow-echo convective system observed with C- and S-band radars. The resulting 3D hydrometeor fields provide a detailed view of the bow-echo microphysical structure and confirm the good performance of both the HCA and interpolation technique. © 2015 Royal Meteorological Society"
"25226875800;7401436524;53980452600;","A new method to compare hourly rainfall between station observations and satellite products over central-eastern China",2016,"10.1007/s13351-016-6002-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992727812&doi=10.1007%2fs13351-016-6002-5&partnerID=40&md5=962043bcede9773bd97a6d952354b951","This study employs a newly defined regional-rainfall-event (RRE) concept to compare the hourly characteristics of warm-season (May-September) rainfall among rain gauge observations, China merged hourly precipitation analysis (CMPA-Hourly), and two commonly used satellite products (TRMM 3B42 and CMORPH). By considering the rainfall characteristics in a given limited area rather than a single point or grid, this method largely eliminates the differences in rainfall characteristics among different observations or measurements over central-eastern China. The results show that the spatial distribution and diurnal variation of RRE frequency and intensity are quite consistent among different datasets, and the performance of CMPA-Hourly is better than the satellite products when compared with station observations. A regional rainfall coefficient (RRC), which can be used to classify local rain and regional rain, is employed to represent the spatial spread of rainfall in the limited region defining the RRE. It is found that rainfall spread in the selected grid box is more uniform during the nocturnal to morning hours over central-eastern China. The RRC tends to reach its diurnal maximum several hours after the RRE intensity peaks, implying an intermediate transition stage from convective to stratiform rainfall. In the afternoon, the RRC reaches its minimum, implying the dominance of local convections on small spatial scale in those hours, which could cause large differences in rain gauge and satellite observations. Since the RRE method reflects the overall features of rainfall in a limited region rather than at a fixed point or in a single grid, the widely recognized overestimation of afternoon rainfall in satellite products is not obvious, and thus the satellite estimates are more reliable in representing sub-daily variation of rainfall from the RRE perspective. This study proposes a reasonable method to compare satellite products with rain gauge observations on the sub-daily scale, which also has great potential to be used in evaluating the spatiotemporal variation of cloud and rainfall in numerical models. © 2016, The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg."
"11340215800;8631019200;15725016900;10738896100;57211869724;57001767400;57188756479;57188760142;","A parameterization scheme of aerosol vertical distribution for surface-level visibility retrieval from satellite remote sensing",2016,"10.1016/j.rse.2016.03.016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962916551&doi=10.1016%2fj.rse.2016.03.016&partnerID=40&md5=88420204763a30f6f0396d5bde4189b5","In this study, a vertical correction method based on a two-layer aerosol model is proposed to estimate the surface-level visibility from satellite measurements of aerosol optical depth (AOD). The meteorological parameters from the re-analysis data of the National Centers for Environmental Prediction (NCEP) are applied to estimate the aerosol layer height (ALH) of the two-layer aerosol model via an automatic workflow. The estimated extinction coefficients near the surface by AOD/ALH over the single point of a lidar site in Shanghai agree well with those of the ground measurements from a visibility sensor, with a correlation coefficient of 0.86 and root mean squared error (RMS) of 0.19 km-1 for the data set from April 18, 2008 to April 30, 2014. The season-long spatial comparison demonstrates that most of the correlation coefficients (90%) are &gt;0.6, and more than half of the samples (68%) have coefficients higher than 0.7 for the data set from January 1 to April 30, 2014. Dust transportation and higher relative humidity (RH) have been confirmed to be important factors in reducing the accuracy of estimated visibility, as these situations fail to meet the assumptions of the two-layer model. Additionally, the less-rigorous cloud mask algorithm of the Moderate Resolution Imaging Spectroradiometer (MODIS)/AOD might lead to overestimates of AOD, and further underestimating of the surface-level visibility. The spatial variation of temporal correlation coefficients shows that most comparison sites (&gt;74%) of satellite estimations agree well with the surface-level visibility measurements, with correlation coefficients up to 0.6 during the study period. The northern area of Eastern China presented better agreement than the southern area. This may be related to the complex underlying surface characteristics and higher RH in the southern part. This work will significantly improve the quality of climate simulations and air quality forecasts in Eastern China. © 2016 Elsevier Inc."
"30667482600;55790615000;57090329000;8045690700;7102517130;7102795549;7004063850;6603372665;35396858200;8643993200;57203776263;26643054400;9435289000;7006686129;7501627905;","Evaluating model parameterizations of submicron aerosol scattering and absorption with in situ data from ARCTAS 2008",2016,"10.5194/acp-16-9435-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979988021&doi=10.5194%2facp-16-9435-2016&partnerID=40&md5=81f21fc2feb433b1535f1d403c584e32","Accurate modeling of the scattering and absorption of ultraviolet and visible radiation by aerosols is essential for accurate simulations of atmospheric chemistry and climate. Closure studies using in situ measurements of aerosol scattering and absorption can be used to evaluate and improve models of aerosol optical properties without interference from model errors in aerosol emissions, transport, chemistry, or deposition rates. Here we evaluate the ability of four externally mixed, fixed size distribution parameterizations used in global models to simulate submicron aerosol scattering and absorption at three wavelengths using in situ data gathered during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The four models are the NASA Global Modeling Initiative (GMI) Combo model, GEOS-Chem v9-02, the baseline configuration of a version of GEOS-Chem with online radiative transfer calculations (called GC-RT), and the Optical Properties of Aerosol and Clouds (OPAC v3.1) package. We also use the ARCTAS data to perform the first evaluation of the ability of the Aerosol Simulation Program (ASP v2.1) to simulate submicron aerosol scattering and absorption when in situ data on the aerosol size distribution are used, and examine the impact of different mixing rules for black carbon (BC) on the results. We find that the GMI model tends to overestimate submicron scattering and absorption at shorter wavelengths by 10-23 %, and that GMI has smaller absolute mean biases for submicron absorption than OPAC v3.1, GEOS-Chem v9-02, or GC-RT. However, the changes to the density and refractive index of BC in GC-RT improve the simulation of submicron aerosol absorption at all wavelengths relative to GEOS-Chem v9-02. Adding a variable size distribution, as in ASP v2.1, improves model performance for scattering but not for absorption, likely due to the assumption in ASP v2.1 that BC is present at a constant mass fraction throughout the aerosol size distribution. Using a core-shell mixing rule in ASP overestimates aerosol absorption, especially for the fresh biomass burning aerosol measured in ARCTAS-B, suggesting the need for modeling the time-varying mixing states of aerosols in future versions of ASP. © Author(s) 2016."
"55682894400;7005031571;35376447600;7102578937;","Tropical tropospheric ozone columns from nadir retrievals of GOME-1/ERS-2, SCIAMACHY/Envisat, and GOME-2/MetOp-A (1996-2012)",2016,"10.5194/amt-9-3407-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979966593&doi=10.5194%2famt-9-3407-2016&partnerID=40&md5=ed66ad3ff5c80bab740fcbf067a1e709","Tropical tropospheric ozone columns are retrieved with the convective cloud differential (CCD) technique using total ozone columns and cloud parameters from different European satellite instruments. Monthly-mean tropospheric column amounts [DU] are calculated by subtracting the above-cloud ozone column from the total column. A CCD algorithm (CCD-IUP) has been developed as part of the verification algorithm developed for TROPOspheric Monitoring Instrument (TROPOMI) on Sentinel 5-precursor (S5p) mission, which was applied to GOME/ERS-2 (1995-2003), SCIAMACHY/Envisat (2002-2012), and GOME-2/MetOp-A (2007-2012) measurements. Thus a unique long-term record of monthly-mean tropical tropospheric ozone columns (20° S-20° N) from 1996 to 2012 is now available. An uncertainty estimation has been performed, resulting in a tropospheric ozone column uncertainty less than 2 DU (< 10 %) for all instruments. The dataset has not been yet harmonised into one consistent; however, comparison between the three separate datasets (GOME/SCIAMACHY/GOME-2) shows that GOME-2 overestimates the tropical tropospheric ozone columns by about 8 DU, while SCIAMACHY and GOME are in good agreement. Validation with Southern Hemisphere ADditional OZonesondes (SHADOZ) data shows that tropospheric ozone columns from the CCD-IUP technique and collocated integrated ozonesonde profiles from the surface up to 200 hPa are in good agreement with respect to range, interannual variations, and variances. Biases within ±5 DU and root-mean-square (RMS) deviation of less than 10 DU are found for all instruments. CCD comparisons using SCIAMACHY data with tropospheric ozone columns derived from limb/nadir matching have shown that the bias and RMS deviation are within the range of the CCD-IUP comparison with the ozonesondes. The 17-year dataset can be helpful for evaluating chemistry models and performing climate change studies. © Author(s) 2016."
"22982270700;56228672600;57196429803;56661876600;","Effects of aerosols on radiative forcing and climate over East Asia with different SO2 emissions",2016,"10.3390/atmos7080099","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983797285&doi=10.3390%2fatmos7080099&partnerID=40&md5=670975bdfe7c7a6c8ff356d05879f08a","It is known that aerosol and precursor gas emissions over East Asia may be underestimated by 50% due to the absence of data on regional rural and township industries. As the most important element of anthropogenic emissions, sulphur dioxide (SO2) can form sulfate aerosols through several chemical processes, thus affecting the regional and global climate. In this study, we use the Community Atmospheric Model 5.1 (CAM5.1) to investigate the effects of anthropogenic aerosols on radiative forcing and the climate over East Asia, taking into consideration various SO2 emission levels, including double the amount of SO2 emissions over East Asia. Numerical experiments are performed using high-resolution CAM5.1 with pre-industrial (PI) and present day (PD) aerosol emission levels, and with PD aerosol emission levels with double SO2 emissions over East Asia (PD2SO2). The simulated aerosol optical depth and surface sulfate concentrations over East Asia are significantly increased in PD2SO2, which is in better agreement with the observational results. The simulation results show extensive aerosol direct and indirect radiative forcing for PD-PI (the difference between PI and PD), which significantly weakens the large-scale intensity of the East Asian summer monsoon (EASM) and reduces the summer precipitation. Compared to PD, the aerosol direct radiative forcing is significantly increased in PD2SO2, whereas the aerosol indirect radiative forcing is markedly decreased due to the inhibition of cloud formation, especially over North China. The increase in aerosol direct radiative forcing and decrease in aerosol indirect radiative forcing result in insignificant changes in the total amount of aerosol radiative forcing. These results also show that the large-scale intensity of the EASM and the associated summer precipitation are insensitive to the doubling of current SO2 emissions. © 2016 by the authors."
"55596887300;7003406400;7102006474;12042092500;7006592026;","Numerical framework and performance of the new multiple-phase cloud microphysics scheme in RegCM4.5: Precipitation, cloud microphysics, and cloud radiative effects",2016,"10.5194/gmd-9-2533-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979929571&doi=10.5194%2fgmd-9-2533-2016&partnerID=40&md5=ade2a44f87a163830cd95e7ad583a26d","We implement and evaluate a new parameterization scheme for stratiform cloud microphysics and precipitation within regional climate model RegCM4. This new parameterization is based on a multiple-phase one-moment cloud microphysics scheme built upon the implicit numerical framework recently developed and implemented in the ECMWF operational forecasting model. The parameterization solves five prognostic equations for water vapour, cloud liquid water, rain, cloud ice, and snow mixing ratios. Compared to the pre-existing scheme, it allows a proper treatment of mixed-phase clouds and a more physically realistic representation of cloud microphysics and precipitation. Various fields from a 10-year long integration of RegCM4 run in tropical band mode with the new scheme are compared with their counterparts using the previous cloud scheme and are evaluated against satellite observations. In addition, an assessment using the Cloud Feedback Model Intercomparison Project (CFMIP) Observational Simulator Package (COSP) for a 1-year sub-period provides additional information for evaluating the cloud optical properties against satellite data. The new microphysics parameterization yields an improved simulation of cloud fields, and in particular it removes the overestimation of upper level cloud characteristics of the previous scheme, increasing the agreement with observations and leading to an amelioration of a long-standing problem in the RegCM system. The vertical cloud profile produced by the new scheme leads to a considerably improvement of the representation of the longwave and shortwave components of the cloud radiative forcing. © Author(s) 2016."
"37032042300;7006146719;57190384098;6603043158;7005287667;8871497700;","Comparison of MODIS and VIIRS cloud properties with ARM ground-based observations over Finland",2016,"10.5194/amt-9-3193-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979642927&doi=10.5194%2famt-9-3193-2016&partnerID=40&md5=14783130109b67362d28138893eb8572","Cloud retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard the satellites Terra and Aqua and the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the Suomi-NPP satellite are evaluated using a combination of ground-based instruments providing vertical profiles of clouds. The ground-based measurements are obtained from the Atmospheric Radiation Measurement (ARM) programme mobile facility, which was deployed in Hyytiälä, Finland, between February and September 2014 for the Biogenic Aerosols-Effects on Clouds and Climate (BAECC) campaign. The satellite cloud parameters cloud top height (CTH) and liquid water path (LWP) are compared with ground-based CTH obtained from a cloud mask created using lidar and radar data and LWP acquired from a multi-channel microwave radiometer. Clouds from all altitudes in the atmosphere are investigated. The clouds are diagnosed as single or multiple layer using the ground-based cloud mask. For single-layer clouds, satellites overestimated CTH by 326 m (14 %) on average. When including multilayer clouds, satellites underestimated CTH by on average 169 m (5.8 %). MODIS collection 6 overestimated LWP by on average 13 g mg-2 (11 %). Interestingly, LWP for MODIS collection 5.1 is slightly overestimated by Aqua (4.56 %) but is underestimated by Terra (14.3 %). This underestimation may be attributed to a known issue with a drift in the reflectance bands of the MODIS instrument on Terra. This evaluation indicates that the satellite cloud parameters selected show reasonable agreement with their ground-based counterparts over Finland, with minimal influence from the large solar zenith angle experienced by the satellites in this high-latitude location. © 2016 Author(s)."
"55258490100;7403076014;57202992636;","A new test statistic for climate models that includes field and spatial dependencies using Gaussian Markov random fields",2016,"10.5194/gmd-9-2407-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979544376&doi=10.5194%2fgmd-9-2407-2016&partnerID=40&md5=d06e9803ba81077acfb9f662b82442ad","A new test statistic for climate model evaluation has been developed that potentially mitigates some of the limitations that exist for observing and representing field and space dependencies of climate phenomena. Traditionally such dependencies have been ignored when climate models have been evaluated against observational data, which makes it difficult to assess whether any given model is simulating observed climate for the right reasons. The new statistic uses Gaussian Markov random fields for estimating field and space dependencies within a first-order grid point neighborhood structure. We illustrate the ability of Gaussian Markov random fields to represent empirical estimates of field and space covariances using ""witch hat"" graphs. We further use the new statistic to evaluate the tropical response of a climate model (CAM3.1) to changes in two parameters important to its representation of cloud and precipitation physics. Overall, the inclusion of dependency information did not alter significantly the recognition of those regions of parameter space that best approximated observations. However, there were some qualitative differences in the shape of the response surface that suggest how such a measure could affect estimates of model uncertainty. © 2016 Author(s)."
"26029329600;56463831800;6506050044;7101653556;56948738800;6701834052;56442378900;","PHIPS-HALO: The airborne Particle Habit Imaging and Polar Scattering probe-Part 1: Design and operation",2016,"10.5194/amt-9-3131-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979642572&doi=10.5194%2famt-9-3131-2016&partnerID=40&md5=3b4f25cec8a74051a36c91e8ec328c35","The number and shape of ice crystals present in mixed-phase and ice clouds influence the radiation properties, precipitation occurrence and lifetime of these clouds. Since clouds play a major role in the climate system, influencing the energy budget by scattering sunlight and absorbing heat radiation from the earth, it is necessary to investigate the optical and microphysical properties of cloud particles particularly in situ. The relationship between the microphysics and the single scattering properties of cloud particles is usually obtained by modelling the optical scattering properties from in situ measurements of ice crystal size distributions. The measured size distribution and the assumed particle shape might be erroneous in case of non-spherical ice particles. There is a demand to obtain both information correspondently and simultaneously for individual cloud particles in their natural environment. For evaluating the average scattering phase function as a function of ice particle habit and crystal complexity, in situ measurements are required. To this end we have developed a novel airborne optical sensor (PHIPS-HALO) to measure the optical properties and the corresponding microphysical parameters of individual cloud particles simultaneously. PHIPS-HALO has been tested in the AIDA cloud simulation chamber and deployed in mountain stations as well as research aircraft (HALO and Polar 6). It is a successive version of the laboratory prototype instrument PHIPS-AIDA. In this paper we present the detailed design of PHIPS-HALO, including the detection mechanism, optical design, mechanical construction and aerodynamic characterization. © 2016 Author(s)."
"57198616562;6603357893;57190341099;57190342446;57190345984;37018824600;57211721176;","Comparison of Vaisala radiosondes RS41 and RS92 at the ARM Southern Great Plains site",2016,"10.5194/amt-9-3115-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979285007&doi=10.5194%2famt-9-3115-2016&partnerID=40&md5=61ecff63f7bcdcb21967ed4a112851fe","In the fall of 2013, the Vaisala RS41 (fourth generation) radiosonde was introduced as a replacement for the RS92-SGP radiosonde with improvements in measurement accuracy of profiles of atmospheric temperature, humidity, and pressure. In order to help characterize these improvements, an intercomparison campaign was undertaken at the US Department of Energy's Atmospheric Radiation Measurement (ARM) Climate Research Facility site in north-central Oklahoma, USA. During 3-8 June 2014, a total of 20 twin-radiosonde flights were performed in a variety of atmospheric conditions representing typical midlatitude continental summertime conditions. The results show that for most of the observed conditions the RS92 and RS41 measurements agree much better than the manufacturer-specified combined uncertainties with notable exceptions when exiting liquid cloud layers where the ""wet-bulbing"" effect appears to be mitigated for several cases in the RS41 observations. The RS41 measurements of temperature and humidity, with applied correction algorithms, also appear to show less sensitivity to solar heating. These results suggest that the RS41 does provide important improvements, particularly in cloudy conditions. For many science applications-such as atmospheric process studies, retrieval development, and weather forecasting and climate modeling-the differences between the RS92 and RS41 measurements should have little impact. However, for long-term trend analysis and other climate applications, additional characterization of the RS41 measurements and their relation to the long-term observational records will be required. © 2016 Author(s)."
"55746116000;6603954179;6603847049;56087160000;","Contrasting radiation and soil heat fluxes in Arctic shrub and wet sedge tundra",2016,"10.5194/bg-13-4049-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978704852&doi=10.5194%2fbg-13-4049-2016&partnerID=40&md5=68c182c3be483a9286db6b373f517acc","Vegetation changes, such as shrub encroachment and wetland expansion, have been observed in many Arctic tundra regions. These changes feed back to permafrost and climate. Permafrost can be protected by soil shading through vegetation as it reduces the amount of solar energy available for thawing. Regional climate can be affected by a reduction in surface albedo as more energy is available for atmospheric and soil heating. Here, we compared the shortwave radiation budget of two common Arctic tundra vegetation types dominated by dwarf shrubs (Betula nana) and wet sedges (Eriophorum angustifolium) in North-East Siberia. We measured time series of the shortwave and longwave radiation budget above the canopy and transmitted radiation below the canopy. Additionally, we quantified soil temperature and heat flux as well as active layer thickness. The mean growing season albedo of dwarf shrubs was 0:15±0:01, for sedges it was higher (0:17±0:02). Dwarf shrub transmittance was 0:36±0:07 on average, and sedge transmittance was 0:28±0:08. The standing dead leaves contributed strongly to the soil shading of wet sedges. Despite a lower albedo and less soil shading, the soil below dwarf shrubs conducted less heat resulting in a 17cm shallower active layer as compared to sedges. This result was supported by additional, spatially distributed measurements of both vegetation types. Clouds were a major influencing factor for albedo and transmittance, particularly in sedge vegetation. Cloud cover reduced the albedo by 0.01 in dwarf shrubs and by 0.03 in sedges, while transmittance was increased by 0.08 and 0.10 in dwarf shrubs and sedges, respectively. Our results suggest that the observed deeper active layer below wet sedges is not primarily a result of the summer canopy radiation budget. Soil properties, such as soil albedo, moisture, and thermal conductivity, may be more influential, at least in our comparison between dwarf shrub vegetation on relatively dry patches and sedge vegetation with higher soil moisture. © 2016 Author(s)."
"55893667900;8618154900;37061102500;57190256186;26425322200;15755536700;57190254183;56121800600;36133343700;","Benchmark campaign and case study episode in central Europe for development and assessment of advanced GNSS tropospheric models and products",2016,"10.5194/amt-9-2989-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978636834&doi=10.5194%2famt-9-2989-2016&partnerID=40&md5=ea1d84b14b9db224d5ed931c048fb225","Initial objectives and design of the Benchmark campaign organized within the European COST Action ES1206 (2013-2017) are described in the paper. This campaign has aimed to support the development and validation of advanced Global Navigation Satellite System (GNSS) tropospheric products, in particular high-resolution and ultrafast zenith total delays (ZTDs) and tropospheric gradients derived from a dense permanent network. A complex data set was collected for the 8-week period when several extreme heavy precipitation episodes occurred in central Europe which caused severe river floods in this area. An initial processing of data sets from GNSS products and numerical weather models (NWMs) provided independently estimated reference parameters - zenith tropospheric delays and tropospheric horizontal gradients. Their provision gave an overview about the product similarities and complementarities, and thus a potential for improvements of a synergy in their optimal exploitations in future. Reference GNSS and NWM results were intercompared and visually analysed using animated maps. ZTDs from two reference GNSS solutions compared to global ERA-Interim reanalysis resulted in accuracy at the 10mm level in terms of the root mean square (rms) with a negligible overall bias, comparisons to Global Forecast System (GFS) forecasts showed accuracy at the 12mm level with the overall bias of -5mm and, finally, comparisons to mesoscale ALADIN-CZ forecast resulted in accuracy at the 8mm level with a negligible total bias. The comparison of horizontal tropospheric gradients from GNSS and NWM data demonstrated a very good agreement among independent solutions with negligible biases and an accuracy of about 0.5 mm. Visual comparisons of maps of zenith wet delays and tropospheric horizontal gradients showed very promising results for future exploitations of advanced GNSS tropospheric products in meteorological applications, such as severe weather event monitoring and weather nowcasting. The GNSS products revealed a capability of providing more detailed structures in atmosphere than the state-of-theart numerical weather models are able to capture. In an initial study on the contribution of hydrometeors (e.g. cloud water, ice or snow) to GNSS signal delays during severe weather, the effect reached up to 17 mm, and it was suggested that hydrometeors should be carefully accounted for within the functional model. The reference products will be further exploited in various specific studies using the Benchmark data set. It is thus going to play a key role in these highly interdisciplinary developments towards better mutual benefits from advanced GNSS and meteorological products. © 2016 Author(s)."
"56400726900;7004154626;57190215589;6701874937;35253736000;7801642681;57190218552;57190216755;","Investigation of aerosol indirect effects on monsoon clouds using ground-based measurements over a high-altitude site in Western Ghats",2016,"10.5194/acp-16-8423-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978370291&doi=10.5194%2facp-16-8423-2016&partnerID=40&md5=5a9d7fb9541b6b94a116612f0302c2d4","The effect of aerosols on cloud droplet number concentration and droplet effective radius is investigated from ground-based measurements over a high-altitude site where clouds pass over the surface. First aerosol indirect effect (AIE) estimates were made using (i) relative changes in cloud droplet number concentration (AIEn/and (ii) relative changes in droplet effective radius (AIEs/with relative changes in aerosol for different cloud liquid water contents (LWCs). AIE estimates from two different methods reveal that there is systematic overestimation in AIEn as compared to that of AIEs. Aerosol indirect effects (AIEn and AIEs/and dispersion effect (DE) at different LWC regimes ranging from 0.05 to 0.50 gm-3 were estimated. The analysis demonstrates that there is overestimation of AIEn as compared to AIEs, which is mainly due to DE. Aerosol effects on spectral dispersion in droplet size distribution play an important role in altering Twomey's cooling effect and thereby changes in climate. This study shows that the higher DE in the medium LWC regime offsets the AIE by 30 %."
"7004198777;9332706900;7004715270;55620143100;57211681908;22953153500;35302719200;15059308500;55807558200;7003789044;","Abundance of fluorescent biological aerosol particles at temperatures conducive to the formation of mixed-phase and cirrus clouds",2016,"10.5194/acp-16-8205-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978285735&doi=10.5194%2facp-16-8205-2016&partnerID=40&md5=5e0a7b3bd919518e6d8cc1e5411dcbff","Some types of biological particles are known to nucleate ice at warmer temperatures than mineral dust, with the potential to influence cloud microphysical properties and climate. However, the prevalence of these particle types above the atmospheric boundary layer is not well known. Many types of biological particles fluoresce when exposed to ultraviolet light, and the Wideband Integrated Bioaerosol Sensor takes advantage of this characteristic to perform real-time measurements of fluorescent biological aerosol particles (FBAPs). This instrument was flown on the National Center for Atmospheric Research Gulfstream V aircraft to measure concentrations of fluorescent biological particles from different potential sources and at various altitudes over the US western plains in early autumn. Clear-air number concentrations of FBAPs between 0.8 and 12 μm diameter usually decreased with height and generally were about 10-100g L-1 in the continental boundary layer but always much lower at temperatures colder than 255 K in the free troposphere. At intermediate temperatures where biological ice-nucleating particles may influence mixed-phase cloud formation (255Kg ≤ T ≤ 270K), concentrations of fluorescent particles were the most variable and were occasionally near boundary-layer concentrations. Predicted vertical distributions of ice-nucleating particle concentrations based on FBAP measurements in this temperature regime sometimes reached typical concentrations of primary ice in clouds but were often much lower. If convection was assumed to lift boundary-layer FBAPs without losses to the free troposphere, better agreement between predicted ice-nucleating particle concentrations and typical ice crystal concentrations was achieved. Ice-nucleating particle concentrations were also measured during one flight and showed a decrease with height, and concentrations were consistent with a relationship to FBAPs established previously at the forested surface site below. The vertical distributions of FBAPs measured on five flights were also compared with those for bacteria, fungal spores, and pollen predicted from the EMAC global chemistry-climate model for the same geographic region. © 2016 Author(s)."
"56289323700;57202803751;6603562731;7005473082;","Top-of-the-atmosphere shortwave flux estimation from satellite observations: An empirical neural network approach applied with data from the A-train constellation",2016,"10.5194/amt-9-2813-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978229784&doi=10.5194%2famt-9-2813-2016&partnerID=40&md5=fcf7ccb5e2925e25c364ff190f86916c","Estimates of top-of-the-atmosphere (TOA) radiative flux are essential for the understanding of Earth's energy budget and climate system. Clouds, aerosols, water vapor, and ozone (O3) are among the most important atmospheric agents impacting the Earth's shortwave (SW) radiation budget. There are several sensors in orbit that provide independent information related to these parameters. Having coincident information from these sensors is important for understanding their potential contributions. The A-train constellation of satellites provides a unique opportunity to analyze data from several of these sensors. In this paper, retrievals of cloud/aerosol parameters and total column ozone (TCO) from the Aura Ozone Monitoring Instrument (OMI) have been collocated with the Aqua Clouds and Earth's Radiant Energy System (CERES) estimates of total reflected TOA outgoing SW flux (SWF). We use these data to develop a variety of neural networks that estimate TOA SWF globally over ocean and land using only OMI data and other ancillary information as inputs and CERES TOA SWF as the output for training purposes. OMI-estimated TOA SWF from the trained neural networks reproduces independent CERES data with high fidelity. The global mean daily TOA SWF calculated from OMI is consistently within ±1 % of CERES throughout the year 2007. Application of our neural network method to other sensors that provide similar retrieved parameters, both past and future, can produce similar estimates TOA SWF. For example, the well-calibrated Total Ozone Mapping Spectrometer (TOMS) series could provide estimates of TOA SWF dating back to late 1978. © Author(s) 2016."
"55512447600;7007051716;7003823107;","Radiative forcing and feedback by forests in warm climates - A sensitivity study",2016,"10.5194/esd-7-535-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978054062&doi=10.5194%2fesd-7-535-2016&partnerID=40&md5=d11967152fda961e90ae5656bf339a66","We evaluate the radiative forcing of forests and the feedbacks triggered by forests in a warm, basically ice-free climate and in a cool climate with permanent high-latitude ice cover using the Max Planck Institute for Meteorology Earth System Model. As a paradigm for a warm climate, we choose the early Eocene, some 54 to 52 million years ago, and for the cool climate, the pre-industrial climate, respectively. To isolate first-order effects, we compare idealised simulations in which all continents are covered either by dense forests or by deserts with either bright or dark soil. In comparison with desert continents covered by bright soil, forested continents warm the planet for the early Eocene climate and for pre-industrial conditions. The warming can be attributed to different feedback processes, though. The lapse-rate and water-vapour feedback is stronger for the early Eocene climate than for the pre-industrial climate, but strong and negative cloud-related feedbacks nearly outweigh the positive lapse-rate and water-vapour feedback for the early Eocene climate. Subsequently, global mean warming by forests is weaker for the early Eocene climate than for pre-industrial conditions. Sea-ice related feedbacks are weak for the almost ice-free climate of the early Eocene, thereby leading to a weaker high-latitude warming by forests than for pre-industrial conditions. When the land is covered with dark soils, and hence, albedo differences between forests and soil are small, forests cool the early Eocene climate more than the pre-industrial climate because the lapse-rate and water-vapour feedbacks are stronger for the early Eocene climate. Cloud-related feedbacks are equally strong in both climates. We conclude that radiative forcing by forests varies little with the climate state, while most subsequent feedbacks depend on the climate state. © Author(s) 2016."
"55463815300;55418587000;55588510300;55885662200;56046400300;8839231800;56900580700;","Global fine-mode aerosol radiative effect, as constrained by comprehensive observations",2016,"10.5194/acp-16-8071-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977602767&doi=10.5194%2facp-16-8071-2016&partnerID=40&md5=bf0e69d6132902179414f6ffe5d04b4e","Aerosols directly affect the radiative balance of the Earth through the absorption and scattering of solar radiation. Although the contributions of absorption (heating) and scattering (cooling) of sunlight have proved difficult to quantify, the consensus is that anthropogenic aerosols cool the climate, partially offsetting the warming by rising greenhouse gas concentrations. Recent estimates of global direct anthropogenic aerosol radiative forcing (i.e., global radiative forcing due to aerosol-radiation interactions) are-0.35 ± 0.5 W m-2, and these estimates depend heavily on aerosol simulation. Here, we integrate a comprehensive suite of satellite and ground-based observations to constrain total aerosol optical depth (AOD), its fine-mode fraction, the vertical distribution of aerosols and clouds, and the collocation of clouds and overlying aerosols. We find that the direct fine-mode aerosol radiative effect is-0.46 W m-2 (-0.54 to-0.39 W m-2). Fine-mode aerosols include sea salt and dust aerosols, and we find that these natural aerosols result in a very large cooling (-0.44 to-0.26 W m-2) when constrained by observations. When the contribution of these natural aerosols is subtracted from the fine-mode radiative effect, the net becomes-0.11 (-0.28 to +0.05) W m-2. This net arises from total (natural + anthropogenic) carbonaceous, sulfate and nitrate aerosols, which suggests that global direct anthropogenic aerosol radiative forcing is less negative than-0.35 W m-2."
"57195727737;57201725986;","Precipitation responses to radiative processes of water- and ice-clouds: an equilibrium cloud-resolving modeling study",2016,"10.1080/16742834.2016.1191938","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075718138&doi=10.1080%2f16742834.2016.1191938&partnerID=40&md5=d04ed94778287334c425edb29dd58b3f","Cloud radiative processes are important in regulating weather and climate. Precipitation responses to radiative processes of water- and ice-clouds are investigated by analyzing mean equilibrium simulation data from a series of two-dimensional cloud-resolving model sensitivity experiments in this study. The model is imposed by zero vertical velocity. The exclusion of water radiative processes in the presence of ice radiative processes, as well as the removal of ice radiative processes, enhances tropospheric longwave radiative cooling and lowers air temperature and the saturation mixing ratio. The reduction in the saturation mixing ratio leads to an increase in vapor condensation and an associated release of latent heat, which increases rainfall. The elimination of water radiative processes strengthens local atmospheric warming in the upper troposphere via a reduction in longwave radiative cooling. The enhanced warming increases the rain source via an increase in the melting of graupel, which increases rainfall. © 2016, © 2016 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group."
"54893098900;7401836526;56909327200;35509639400;7202660824;7403288995;","Shallowness of tropical low clouds as a predictor of climate models’ response to warming",2016,"10.1007/s00382-015-2846-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944542733&doi=10.1007%2fs00382-015-2846-0&partnerID=40&md5=5c0f303f6cad1b676cbf60e260bc4e77","How tropical low clouds change with climate remains the dominant source of uncertainty in global warming projections. An analysis of an ensemble of CMIP5 climate models reveals that a significant part of the spread in the models’ climate sensitivity can be accounted by differences in the climatological shallowness of tropical low clouds in weak-subsidence regimes: models with shallower low clouds in weak-subsidence regimes tend to have a higher climate sensitivity than models with deeper low clouds. The dynamical mechanisms responsible for the model differences are analyzed. Competing effects of parameterized boundary-layer turbulence and shallow convection are found to be essential. Boundary-layer turbulence and shallow convection are typically represented by distinct parameterization schemes in current models—parameterization schemes that often produce opposing effects on low clouds. Convective drying of the boundary layer tends to deepen low clouds and reduce the cloud fraction at the lowest levels; turbulent moistening tends to make low clouds more shallow but affects the low-cloud fraction less. The relative importance different models assign to these opposing mechanisms contributes to the spread of the climatological shallowness of low clouds and thus to the spread of low-cloud changes under global warming. © 2015, Springer-Verlag Berlin Heidelberg."
"7007088807;7801552221;23096906200;","Reconstruction of effective cloud field geometry from series of sunshine number",2016,"10.1016/j.atmosres.2016.03.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962567446&doi=10.1016%2fj.atmosres.2016.03.004&partnerID=40&md5=2565315fc76ea9d41dd2fbe21d91d88c","A new method is proposed for extracting the parameters of effective cloud field models from time series of sunshine number (SSN). Data of SSN number and point cloudiness during 2009 and 2010 at Timisoara (Romania, South Eastern Europe; temperate continental climate) are used to illustrate the method. Two procedures of fitting the estimated point cloudiness to the observed point cloudiness data are proposed and tested. Seven simple effective cloud field models are analyzed. All models underestimate the point cloudiness. The MBE ranges between - 0.06 and - 0.23 while RMSE between 0.15 and 0.38, depending on the month and the duration of the SSN data averaging interval. The best model is based on a field of clouds of semicircle form. This agrees with previous results obtained in the semi-arid climate of Great South Plains in US. The dynamics of the effective cloud field is reconstructed during all months of 2010 at Timisoara. The time series of effective cloud fields are dominated by semicircle clouds but short episodes of semielliptic clouds, ellipsoid clouds, truncated cone clouds and cuboidal clouds are included in the series. © 2016 Elsevier B.V.."
"26655075300;7102171439;56219284300;6603631763;","Subpixel characterization of HIRS spectral radiances using cloud properties from AVHRR",2016,"10.1175/JTECH-D-15-0187.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981278166&doi=10.1175%2fJTECH-D-15-0187.1&partnerID=40&md5=f0f320b7ce5438f6e062db35726b2738","This paper describes a cloud type radiance record derived from NOAA polar-orbiting weather satellites using cloud properties retrieved from the Advanced Very High Resolution Radiometer (AVHRR) and spectral brightness temperatures (Tb) observed by the High Resolution Infrared Radiation Sounder (HIRS). The authors seek to produce a seamless, global-scale, long-term record of cloud type and Tb statistics intended to better characterize clouds from seasonal to decadal time scales. Herein, the methodology is described in which the cloud type statistics retrieved from AVHRR are interpolated onto each HIRS footprint using two cloud classification methods. This approach is tested over the northeast tropical and subtropical Pacific Ocean region, which contains a wide variety of cloud types during a significant ENSO variation from 2008 to 2009. It is shown that the Tb histograms sorted by cloud type are realistic for all HIRS channels. The magnitude of Tb biases among spatially coincident satellite intersections over the northeast Pacific is a function of cloud type and wavelength. While the sign of the bias can change, the magnitudes are generally small for NOAA-18 and NOAA-19, and NOAA-19 and MetOp-A intersections. The authors further show that the differences between calculated standard deviations of cloud-typed Tb well exceed intersatellite calibration uncertainties. The authors argue that consideration of higher-order statistical moments determined from spectral infrared observations may serve as a useful long-term measure of small-scale spatial changes, in particular cloud types over the HIRS-AVHRR observing record. © 2016 American Meteorological Society."
"56898396100;23028245500;15051249600;55574869900;57190286025;","Observation of clouds macrophysical characteristics in China by CALIPSO",2016,"10.1117/1.JRS.10.036028","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989184484&doi=10.1117%2f1.JRS.10.036028&partnerID=40&md5=51d8b31a163c8e7b3ce18d0d68508370","Clouds' macrophysical characteristics play an important role in the climate system and dramatically vary because of the diverse climatic and geographic factors in China. We analyze cloud macrophysical characteristics and the differences between subregions in China (18°-54°N, 73°-135°E) from March 2012 to February 2015 based on Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations, including cloud fractions, cloud vertical distribution, and cloud geometrical properties with the perspective of daytime and nighttime. We found that annual single layer, multilayer (ML), and total cloud fractions are 40.4±1.1%, 22.4±0.4%, and 62.8±1.5%, respectively, and clouds are generally located between 6 and 12 km. The cloud fractions in daytime are less than that in nighttime over the south while that of Tibet shows the reverse trend. In the vertical direction, except for Tibet, the clouds in nighttime have larger spatial coverage and are higher in altitude than that in daytime. The regional average values of cloud macrophysical characteristics in the south are highest, followed successively by Tibet, north, and northwest. Cloud geometrical depth and spacing show a gradually declining trend with the increase in layers and decrease of altitude in ML cloud system. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE)."
"56766263400;24315205000;7003548068;55450672000;7401776640;","Cloud cover climatologies in the Mediterranean obtained from satellites, surface observations, reanalyses, and CMIP5 simulations: validation and future scenarios",2016,"10.1007/s00382-015-2834-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84942026582&doi=10.1007%2fs00382-015-2834-4&partnerID=40&md5=51ca9c8d9096b9eed96800d755d9c3ba","Clouds are an important regulator of climate due to their connection to the water balance of the atmosphere and their interaction with solar and infrared radiation. In this study, monthly total cloud cover (TCC) records from different sources have been inter-compared on annual and seasonal basis for the Mediterranean region and the period 1984–2005. Specifically, gridded databases from satellite projects (ISCCP, CLARA, PATMOS-x), from reanalysis products (ERA-Interim, MERRA), and from surface observations over land (EECRA) and ocean (ICOADS) have been examined. Then, simulations from 44 climate runs of the Coupled Model Intercomparison Project phase 5 corresponding to the historical scenario have been compared against the observations. Overall, we find good agreement between the mean values of TCC estimated from the three satellite products and from surface observations, while reanalysis products show much lower values across the region. Nevertheless, all datasets show similar behavior regarding the annual cycle of TCC. In addition, our results indicate an underestimation of TCC from climate model simulations as compared to the satellite products, especially during summertime, although the annual cycle is well simulated by most models. This result is quite general and apparently independent of the cloud parameterizations included in each particular model. Equally, similar results are obtained if the ISCCP simulator included in the Cloud Feedback Model Intercomparison Project Observation Simulator Package is considered, despite only few models provide the post-processed results. Finally, GCM projections of TCC over the Mediterranean are presented. These projections predict a reduction of TCC during the 21st century in the Mediterranean. Specifically, for an extreme emission scenario (RCP8.5) the projected relative rate of TCC decrease is larger than 10 % by the end of the century. © 2015, Springer-Verlag Berlin Heidelberg."
"56001325100;14322050300;36107172000;6603327055;","Analysis of ERA-Interim-driven COSMO-CLM simulations over Middle East – North Africa domain at different spatial resolutions",2016,"10.1002/joc.4559","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84950327105&doi=10.1002%2fjoc.4559&partnerID=40&md5=02e16fb6a6379163675fff95aef26d7f","This study aimed to assess the capabilities of the regional climate model (RCM) COSMO-CLM in reproducing the main climate features of the Middle East and Northern Africa (MENA) domain. Two ERA-Interim-driven simulations were performed at 0.44° and 0.22° spatial resolution for the period 1979–2011 with an optimized model configuration. Model response has been analysed in terms of low level circulation, 2-m temperature, precipitation and cloud cover. Evaluation was conducted with respect to a combination of available ground observations, satellite products and reanalysis. Results reveal a good accuracy of the model in reproducing the circulation and a satisfactory representation of temperature, compared with other state-of-art RCMs, confirming that the albedo and aerosol parameterization schemes adopted lead to a remarkable improvement in model performances. The effects of increasing spatial resolution on the quality of the results have also been investigated. A comparison between the two simulations revealed that improvements with the resolution increase have been achieved for the temperature interannual variability, for monthly precipitation mean values, for cloud cover and for the representation of extreme precipitation events. © 2015 Royal Meteorological Society"
"56264253200;7005321613;","Global patterns of solar influence on high cloud cover",2016,"10.1007/s00382-015-2862-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944557094&doi=10.1007%2fs00382-015-2862-0&partnerID=40&md5=bb01ead06b48b935c3776a697f76d1f0","One of the main sources of uncertainty in climate projections is represented by clouds, which have a profound influence on the Earth’s radiation budget through the feedbacks in which they are involved. The improvement of clouds representation in General Circulation Models relies largely on constraints derived from observations and on correct identification of processes that influence cloud formation or lifetime. Here we identify solar forced high cloud cover (HCC) patterns in reanalysis and observed data extending over the 1871–2009 period, based on their associations with known fingerprints of the same forcing on surface air temperature, sea surface temperature (SST) and sea level pressure fields. The solar influence on HCC has maximum amplitudes over the Pacific basin, where HCC anomalies are distributed in bands of alternating polarities. The colocation of the HCC and SST anomalies bands indicates a thermal influence on high clouds through convection and an amplification of the HCC anomalies by a positive feedback of long-wave fluxes, which increases the solar signal. Consistent with numerical simulations, the solar forced HCC pattern appears to be generated through a constructive interference between the so-called “top-down” and “bottom-up” mechanisms of solar influence on climate and is amplified by ocean–atmosphere positive feedbacks. © 2015, Springer-Verlag Berlin Heidelberg."
"7004091067;7005773698;7005265210;8147766700;7004715270;7004651463;22975069200;7202048112;7102084129;7005461477;7003278104;7404187535;14018977200;55968364300;57203247274;6603746990;","Calwater field studies designed to quantify the roles of atmospheric rivers and aerosols in modulating U.S. West Coast Precipitation in a changing climate",2016,"10.1175/BAMS-D-14-00043.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984844782&doi=10.1175%2fBAMS-D-14-00043.1&partnerID=40&md5=fc9f6024e237dad4062d1c2d4beadf7d","The variability of precipitation and water supply along the U.S. West Coast creates major challenges to the region's economy and environment, as evidenced by the recent California drought. This variability is strongly influenced by atmospheric rivers (ARs), which deliver much of the precipitation along the U.S. West Coast and can cause flooding, and by aerosols (from local sources and transported from remote continents and oceans) that modulate clouds and precipitation. A better understanding of these processes is needed to reduce uncertainties in weather predictions and climate projections of droughts and floods, both now and under changing climate conditions. To address these gaps, a group of meteorologists, hydrologists, climate scientists, atmospheric chemists, and oceanographers have created an interdisciplinary research effort, with support from multiple agencies. From 2009 to 2011 a series of field campaigns [California Water Service (CalWater) 1] collected atmospheric chemistry, cloud microphysics, and meteorological measurements in California and associated modeling and diagnostic studies were carried out. Based on the remaining gaps, a vision was developed to extend these studies offshore over the eastern North Pacific and to enhance land-based measurements from 2014 to 2018 (CalWater-2). The dataset and selected results from CalWater-1 are summarized here. The goals of CalWater-2, and measurements to date, are then described. CalWater is producing new findings and exploring new technologies to evaluate and improve global climate models and their regional performance and to develop tools supporting water and hydropower management. These advances also have potential to enhance hazard mitigation by improving near-term weather prediction and subseasonal and seasonal outlooks. ©2016 American Meteorological Society."
"55860378000;9636267700;7003795435;8304718100;7004381336;","Using satellite-derived optical thickness to assess the influence of clouds on terrestrial carbon uptake",2016,"10.1002/2016JG003365","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978087139&doi=10.1002%2f2016JG003365&partnerID=40&md5=ad79efe738af1d712a6ea9260b33d1be","Clouds scatter direct solar radiation, generating diffuse radiation and altering the ratio of direct to diffuse light. If diffuse light increases plant canopy CO2 uptake, clouds may indirectly influence climate by altering the terrestrial carbon cycle. However, past research primarily uses proxies or qualitative categories of clouds to connect the effect of diffuse light on CO2 uptake to sky conditions. We mechanistically link and quantify effects of cloud optical thickness (τc) to surface light and plant canopy CO2 uptake by comparing satellite retrievals of τc to ground-based measurements of diffuse and total photosynthetically active radiation (PAR; 400–700 nm) and gross primary production (GPP) in forests and croplands. Overall, total PAR decreased with τc, while diffuse PAR increased until an average τc of 6.8 and decreased with larger τc. When diffuse PAR increased with τc, 7–24% of variation in diffuse PAR was explained by τc. Light-use efficiency (LUE) in this range increased 0.001–0.002 per unit increase in τc. Although τc explained 10–20% of the variation in LUE, there was no significant relationship between τc and GPP (p &gt; 0.05) when diffuse PAR increased. We conclude that diffuse PAR increases under a narrow range of optically thin clouds and the dominant effect of clouds is to reduce total plant-available PAR. This decrease in total PAR offsets the increase in LUE under increasing diffuse PAR, providing evidence that changes within this range of low cloud optical thickness are unlikely to alter the magnitude of terrestrial CO2 fluxes. ©2016. American Geophysical Union. All Rights Reserved."
"55656353100;57218273453;56962915800;","Reducing the biases in shortwave cloud radiative forcing in tropical and subtropical regions from the perspective of boundary layer processes",2016,"10.1007/s11430-016-5290-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962909734&doi=10.1007%2fs11430-016-5290-z&partnerID=40&md5=593a67dff057af9901ec43047f2f7d5d","Biases in shortwave cloud radiative forcing (SWCF), which cause overestimates in tropical regions and underestimates in subtropical marine stratocumulus regions, are common in many climate models. Here, two boundary layer processes are investigated in the atmospheric model GAMIL2, entrainment at the top of the boundary layer and longwave radiative cooling at the top of stratocumulus clouds, in order to reduce biases and reveal the mechanisms underlying these processes. Our results show that including the entrainment process in the model can reduce negative SWCF biases in most tropical regions but increases positive SWCF biases in subtropical marine stratocumulus regions. This occurs because entrainment reduces the low-level cloud fraction and its cloud liquid water content by suppressing the vertical turbulent diffusion in the boundary layer and decreasing the relative humidity when warm and dry free atmosphere is entrained in the boundary layer. Longwave radiative cooling at the top of stratocumulus clouds can enhance turbulent diffusion within the stratocumulus-topped boundary layer. When combined with the entrainment process, longwave radiative cooling reduces the positive SWCF biases in subtropical marine stratocumulus regions that are observed using the entrainment process alone. The incorporation of these two boundary layer processes improves the simulated SWCF in tropical and subtropical regions in GAMIL2. © 2016, Science China Press and Springer-Verlag Berlin Heidelberg."
"57008250400;7101752236;9535707500;","Aerosol indirect effects on glaciated clouds. Part 2: Sensitivity tests using solute aerosols",2016,"10.1002/qj.2790","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971330338&doi=10.1002%2fqj.2790&partnerID=40&md5=991dfa00353e44f96773fc89d5d8f88b","Sensitivity tests were performed on a midlatitude continental case using a state-of-the-art aerosol–cloud model to determine the salient mechanisms of aerosol indirect effects (AIE) from solute aerosols. The simulations showed that increased solute aerosols doubled cloud-droplet number concentrations and hence reduced cloud particle sizes by about 20% and consequently inhibited warm rain processes, thus enhancing the chances of homogeneous freezing of cloud droplets and aerosols. Cloud fractions and their optical thicknesses increased quite substantially with increasing solute aerosols. Although liquid mixing ratios were boosted, there was, however, a substantial reduction of ice mixing ratios in the upper troposphere, owing to the increase in snow production aloft. The predicted total aerosol indirect effect was equal to −9.46 ± 1.4 W m−2. The AIEs of glaciated clouds (−6.33 ± 0.95 W m−2) were greater than those of water-only clouds (−3.13 ± 0.47 W m−2) by a factor of two in this continental case. The higher radiative importance of glaciated clouds compared with water-only clouds emerged from their larger collective spatial extent and their existence above water-only clouds. In addition to the traditional AIEs (glaciation, riming and thermodynamic), the new AIEs sedimentation, aggregation and coalescence were identified. © 2016 Royal Meteorological Society"
"57188754625;8649203100;24079063700;23982847500;","Cloud properties during active and break spells of the West African summer monsoon from CloudSat-CALIPSO measurements",2016,"10.1016/j.jastp.2016.04.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962808990&doi=10.1016%2fj.jastp.2016.04.001&partnerID=40&md5=e296ea62623fc1cd540e09590fb05982","High resolution of daily rainfall dataset from the Tropical Rainfall Measuring Mission (TRMM) was used to identify active and break cloud formation periods. The clouds were characterized based on CloudSat-CALIPSO satellite images over West Africa during the summer monsoon during the period 2006-2010. The active and break periods are defined as the periods during the peak monsoon months of June to August when the normalized anomaly of rainfall over the monsoon core zone is greater than 0.9 or less than -0.9 respectively, provided the criteria is satisfied for at least three consecutive days. It is found that about 90% of the break period and 66.7% of the active spells lasted 3-4 days. Active spells lasting duration of about a week were observed while no break spell had such a long span. Cloud macrophysical (cloud base height (CBH), cloud top height (CTH) and cloud geometric depth ((increment)H), microphysical (cloud liquid water content, (LWC), liquid number concentration (LNC), liquid effective radius, ice water content (IWC), ice number concentration (INC) and ice effective radius) and radiative (heating rate properties) over South Central West Africa (5-15°N; 15°W-10°E) during the active and break spells were also analyzed. High-level clouds are more predominant during the break periods compared to the active periods. Active spells have lower INC compared to the break spells. Liquid water clouds are observed to have more radiative forcing during the active than break periods while ice phase clouds bring more cooling effect during the break spells compared to the active spells. © 2016 Elsevier Ltd."
"15047538100;15050523700;36242447900;10045312900;6602135370;","Indian summer monsoon simulations with CFSv2: a microphysics perspective",2016,"10.1007/s00704-015-1515-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84929688915&doi=10.1007%2fs00704-015-1515-x&partnerID=40&md5=394a8b15b3d3d6e81623e0b3db1ca72a","The present study explores the impact of two different microphysical parameterization schemes (i.e. Zhao and Carr, Mon Wea Rev 125:1931-1953, 1997:called as ZC; Ferrier, Amer Meteor Soc 280-283, 2002: called as BF) of National Centers for Environmental Prediction (NCEP) Climate Forecast System version 2 (CFSv2) on Indian summer monsoon (ISM). Critical relative humidity (RHcrit) plays a crucial role for the realistic cloud formation in a general circulation model (GCM). Hence, impact of RHcrit along with microphysical scheme on ISM is evaluated in the study. Model performance is evaluated in terms of simulation of rainfall, lower and upper tropospheric circulations, cloud fraction, cloud condensate and outgoing longwave radiation (OLR). Climatological mean features of rainfall are better represented by all the sensitivity experiments. Overall, ZC schemes show relatively better rainfall patterns as compared to BF schemes. BF schemes along with 95 % RHcrit (called as BF95) show excess precipitable water over Indian Ocean basin region, which seems to be unrealistic. Lower and upper tropospheric features are well simulated in all the sensitivity experiments; however, upper tropospheric wind patterns are underestimated as compared to observation. Spatial pattern and vertical profile of cloud condensate is relatively better represented by ZC schemes as compared to BF schemes. Relatively more (less) cloud condensate at upper level has lead to relatively better (low) high cloud fraction in ZC (BF) simulation. It is seen that OLR in ZC simulation have great proximity with observation. ZC (BF) simulations depict low (high) OLR which indicates stronger (weaker) convection during ISM period. It implies strong (weak) convection having stronger (weaker) updrafts in ZC (BF). Relatively more (less) cloud condensate at upper level of ZC (BF) may produce strong (weak) latent heating which may lead to relatively strong (weak) convection during ISM. The interaction among microphysics, thermodynamics, and dynamics works in tandem through a closed feedback loop. © 2015, Springer-Verlag Wien."
"55317177900;7006705919;55688930000;6508063123;57214786060;","The role of carbonaceous aerosols on short-term variations of precipitation over North Africa",2016,"10.1002/asl.672","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977484729&doi=10.1002%2fasl.672&partnerID=40&md5=ca7aa8f7651075fc99286db6c1798b9a","Subtropical North Africa has been subject to extensive droughts in the late 20th century, linked to changes in the sea surface temperature (SST). However, climate models forced by observed SSTs cannot reproduce the magnitude of the observed rainfall reduction. Here, we propose aerosol indirect effects (AIE) as an important positive feedback mechanism. Model results are presented using two sets of sensitivity experiments designed to distinguish the role of aerosol direct/semi-direct and indirect effects on regional precipitation. Changes in cloud properties due to the presence of carbonaceous aerosols are proposed as a key mechanism to explain the reduced rainfall over subtropical North Africa. © 2016 The Authors. Atmospheric Science Letters published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"55762460400;56963713700;55762520100;14061506600;6602182845;57213035757;6701416358;7102395993;","MODSNOW-Tool: an operational tool for daily snow cover monitoring using MODIS data",2016,"10.1007/s12665-016-5869-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978633511&doi=10.1007%2fs12665-016-5869-x&partnerID=40&md5=3e0baed7c37e8270153675605606e2e0","Spatially distributed snow cover information is important for the assessment of climate-related variability of water resources and for calibration and validation of hydrological models in snow-dominated regions. Near-real-time snow cover data can be valuable for short term to seasonal streamflow prediction. Such information can be extracted using remote sensing techniques with good accuracy. Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover data, meanwhile available for more than 15 years, have been shown to be useful for monitoring snow cover extent in remote areas. This data can be processed and used with only 2-day delay, which is sufficient for many water resources management purposes. However, processing remote sensing data require knowledge and computational skills to handle large amounts of data. Moreover, cloud obscuration in optical remote sensing such as MODIS may lead to data gaps. These limitations impede the use of the freely available MODIS data for water resources management in developing countries, particularly in snow-dominated mountainous regions. To overcome this, we present the all-in-one software package MODSNOW-Tool. It processes raw MODIS data and eliminates cloud cover using advanced cloud removal algorithms. The ready-to-use output of the MODSNOW-Tool is a cloud-free snow cover map and a daily report, which includes spatiotemporal snow statistics for pre-defined river basins. The accuracy of cloud-eliminated MODSNOW snow cover maps was validated for 84 almost cloud-free days in the Karadarya river basin in Central Asia, and an average accuracy of 94 % was achieved. The MODSNOW-Tool can be used in operational and non-operational mode. In the operational mode, the tool is set up as a scheduled task on a local computer allowing automatic execution without user interaction and delivers snow cover maps on a daily basis. In the non-operational mode, the tool can be used to process historical time series of snow cover maps from MODIS. © 2016, Springer-Verlag Berlin Heidelberg."
"57189216137;7501793055;12794036300;55720588700;","Life cycle characteristics of MCSs in Middle East China tracked by geostationary satellite and precipitation estimates",2016,"10.1175/MWR-D-15-0197.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978036126&doi=10.1175%2fMWR-D-15-0197.1&partnerID=40&md5=9cae99938486250c7adfc120653310a8","By combining high temporal and spatial resolution Multifunctional Transport Satellite-1R (MTSAT-1R) infrared (IR) images and precipitation data from the Climate Prediction Center morphing technique (CMORPH), this study tracked mesoscale convective systems (MCSs) from May to August in 2008 and 2009 in the middle of east China with an automatic tracking algorithm based on an areal overlapping methodology. This methodology is adjusted to include those MCSs with a relative weak intensity before formation. The unique advantage of combining high temporal and spatial resolution geostationary satellite brightness temperature images and the precipitation measurements for tracking MCSs is that the cloud-top height along with the coverage and the precipitation intensity can be well identified. Results showed that the MCSs formed most frequently in the southwest Henan Province and at the border of four provinces-Shandong, Henan, Anhui, and Jiangsu-which is east of the convergence zone near the terrain's edge. Locations of the highest cloud tops and of the heaviest precipitation rates did not always match. In addition, the MCSs in the study region tended to first reach the maximum precipitation rate, followed soon by the minimum brightness temperature, then the maximum associated precipitation area, and finally the maximum in system area. © 2016 American Meteorological Society."
"56423739200;56465612000;15070397200;7801654745;8290789800;12040851700;6603476391;","Influence of the Indian Ocean Dipole on tree-ring δ18O of monsoonal Southeast Tibet",2016,"10.1007/s10584-016-1663-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962712362&doi=10.1007%2fs10584-016-1663-8&partnerID=40&md5=3c1eec24565597483e3fb495a13ef426","We present a newly developed, annually resolved tree-ring cellulose δ18O chronology for the southeastern Tibetan Plateau (TP) from Sikkim larch (Larix griffithii), spanning between 1684 and 2012. Comparisons with local and regional climate data reveal strong positive correlations with monthly sunshine hours, temperature and daily temperature amplitude as well as strong negative correlations with relative humidity, vapor pressure, rain days per month and cloud cover of August. Relationships with local and regional tree-ring δ18O chronologies are stable and highly significant. Over the 20th century, we find no long-term climatic trends. This is consistent with other tree-ring δ18O chronologies of other tree species south of the Himalayas, but contrasts with results from isotope studies north of the Himalayas. This suggests stable macroclimatic flow patterns throughout the last centuries for the southern tree stands. In terms of large-scale climate dynamics, we find evidence of a significant 30-year wave influencing our tree-ring oxygen chronology, most probably induced by the Indian Ocean Dipole and influencing tree-ring oxygen isotope chronologies along the southeastern Himalaya and the southeastern rim of the TP. This pattern is spatially and temporarily consistent among the chronologies and has apparently strengthened during the last century. During periods of strong positive dipole mode activity, the dipole mode index shows positive correlations with the δ18O of tree-rings on the southeastern TP. © 2016, Springer Science+Business Media Dordrecht."
"37114498900;14012082000;7005212820;36843654900;","Tropical cyclone activity in nested regional and global grid-refined simulations",2016,"10.1007/s00382-015-2852-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944584969&doi=10.1007%2fs00382-015-2852-2&partnerID=40&md5=a59035e66929661b3dba9d13ca397bac","The capacity of two different grid refinement methods—two-way limited area nesting and variable-mesh refinement—to capture Northwest Pacific Tropical Cyclone (TC) activity is compared in a suite of single-year continuous simulations. Simulations are conducted with and without regional grid refinement from approximately 100–20 km grid spacing over the Northwest Pacific. The capacity to capture smooth transitions between the two resolutions varies by grid refinement method. Nesting shows adverse influence of the nest boundary, with the boundary evident in seasonal average cloud patterns and precipitation, and contortions of the seasonal mean mid-latitude jet. Variable-mesh, on the other hand, reduces many of these effects and produced smoother cloud patterns and mid-latitude jet structure. Both refinement methods lead to increased TC frequency in the region of refinement compared to simulations without grid refinement, although nesting adversely affects TC tracks through the contorted mid-latitude jet. The variable-mesh approach leads to enhanced TC activity over the Southern Indian and Southwest Pacific basins, compared to a uniform mesh simulation. Nesting, on the other hand, does not appear to influence basins outside the region of grid refinement. This study provides evidence that variable mesh may bring benefits to seasonal TC simulation over traditional nesting, and demonstrates capacity of variable mesh refinement for regional climate simulation. © 2015, The Author(s)."
"57192976480;8699594600;57210032641;7006119097;","The HD(CP)2 data archive for atmospheric measurement data",2016,"10.3390/ijgi5070124","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984823117&doi=10.3390%2fijgi5070124&partnerID=40&md5=bc2d0f77c2fc1823dfb5ddbe77cf24eb","The archiving of scientific data is a sophisticated mission in nearly all research projects. In this paper, we introduce a new online archive of atmospheric measurement data from the ""High definition clouds and precipitation for advancing climate prediction"" (HD(CP)2) research initiative. The project data archive is quality managed, easy to use, and is now open for other atmospheric research data. The archive's creation was already taken into account during the HD(CP)2 project planning phase and the necessary resources were granted. The funding enabled the HD(CP)2 project to build a sound archive structure, which guarantees that the collected data are accessible for all researchers in the project and beyond. © 2016 by the authors; licensee MDPI, Basel, Switzerland."
"40661134200;55512919600;56603483200;55748567100;36619804000;56539489100;56421015100;","Large-scale urbanization effects on eastern Asian summer monsoon circulation and climate",2016,"10.1007/s00382-015-2827-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84940850327&doi=10.1007%2fs00382-015-2827-3&partnerID=40&md5=f36de10180cf28ece71c7490fb2055bc","Impacts of large-scale urbanization over eastern China on East Asian summer monsoon circulation and climate are investigated by comparing three 25-year climate simulations with and without incorporating modified land cover maps reflecting two different idealized large-scale urbanization scenarios. The global atmospheric general circulation model CAM4.0 that includes an urban canopy parameterization scheme is employed in this study. The large-scale urbanization over eastern China leads to a significant warming over most of the expanded urban areas, characterized by an increase of 3 K for surface skin temperature, 2.25 K for surface air temperature, significant warming of both daily minimum and daily maximum air temperatures, and 0.4 K for the averaged urban–rural temperature difference. The urbanization is also accompanied by an increase in surface sensible heat flux, a decrease of the net surface shortwave and long-wave radiation, and an enhanced surface thermal heating to the atmosphere in most Eastern Asia areas. It is noted that the responses of the East Asian summer monsoon circulation exhibits an evident month-to-month variation. Across eastern China, the summer monsoon in early summer is strengthened by the large-scale urbanization, but weakened (intensified) over southern (northern) part of East Asia in late summer. Meanwhile, early summer precipitation is intensified in northern and northeastern China and suppressed in south of ~35°N, but late summer precipitation is evidently suppressed over northeast China, the Korean Peninsula and Japan with enhancements in southern China, the South China Sea, and the oceanic region south and southeast of the Taiwan Island. This study highlights the evidently distinct month-to-month responses of the monsoon system to the large-scale urbanization, which might be attributed to different basic states, internal feedbacks (cloud, rainfall) as well as a dynamic adjustment of the atmosphere. Further investigation is required to understand the dynamic mechanisms by which a large-scale urbanization in China affects eastern Asian climate and summer monsoon circulation, especially possible internal feedbacks relevant to the sub-seasonal changes of the monsoon system. © 2015, Springer-Verlag Berlin Heidelberg."
"57003940300;57030999500;56609511500;35329984300;57213512007;55814523900;","The assessment of droughts in Northern China and Mongolian areas using PDSI and relevant large-scale environments",2016,"10.1002/joc.4553","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84952673991&doi=10.1002%2fjoc.4553&partnerID=40&md5=5d8ea4617dd705bb14e9f4de9a63d1d6","This study assessed drought conditions in northern China and Mongolian areas using the Palmer drought severity index (PDSI). Droughts in this area were intensified throughout all seasons. In particular, this intensifying trend was pronounced in the summer and autumn. In the summer, the PDSI showed an overall increase from the early 1990s to the late 1990s, and then, it rapidly decreased after the late 1990s. Therefore, this study focused on summer droughts and analysed mean differences before the late 1990s (9098) and after the late 1990s (9905). Regarding differences in 850 hPa stream flows between the two periods, anomalous anticyclonic circulations were strengthened in northern China and Mongolia that showed strong negative anomalies in the PDSI. These anomalous anticyclones were formed as a positive North Atlantic Oscillation pattern formed in the European region spread eastward in the form of wave trains. The anomalous anticyclones formed in northern China and Mongolia led to reduced total cloud cover. As a result, this region exhibited high sensible heat net fluxes. Consequently, warm and dry anticyclones may have recently been strengthened in this region, thereby intensifying droughts. As this shows, recently strengthened warm and dry anticyclones in northern China and Mongolia were associated with recently reduced snow depths in this region during the preceding spring. In recent years, the frequency of Asian dust has also increased due to warm and dry air conditions. © 2015 Royal Meteorological Society"
"6506883710;25031430500;8058018000;57209437917;7006747377;16402575500;9244992800;7004168515;55893823700;7202489497;13402933200;7103294731;7102167757;7005134081;6507562207;7402093416;9738329300;56259852000;6603480361;55393706100;6603821988;7004402705;55919935700;6504688501;13609746100;16479703400;23485410200;15127430500;6701511321;7102976560;8263760800;6506553245;7004587644;55812487100;6602414959;57062286700;7003800456;7005723936;7006532784;7003683808;6603561402;7403544649;57206421971;36465590400;21735369200;55730744700;","Multimodel assessment of the upper troposphere and lower stratosphere: Extratropics",2016,"10.1029/2010JD013884","https://www.scopus.com/inward/record.uri?eid=2-s2.0-77955898761&doi=10.1029%2f2010JD013884&partnerID=40&md5=0fd4777ad1585f193bd2ebe78ad6093c","A multimodel assessment of the performance of chemistry-climate models (CCMs) in the extratropical upper troposphere/lower stratosphere (UTLS) is conducted for the first time. Process-oriented diagnostics are used to validate dynamical and transport characteristics of 18 CCMs using meteorological analyses and aircraft and satellite observations. The main dynamical and chemical climatological characteristics of the extratropical UTLS are generally well represented by the models, despite the limited horizontal and vertical resolution. The seasonal cycle of lowermost stratospheric mass is realistic, however with a wide spread in its mean value. A tropopause inversion layer is present in most models, although the maximum in static stability is located too high above the tropopause and is somewhat too weak, as expected from limited model resolution. Similar comments apply to the extratropical tropopause transition layer. The seasonality in lower stratospheric chemical tracers is consistent with the seasonality in the Brewer-Dobson circulation. Both vertical and meridional tracer gradients are of similar strength to those found in observations. Models that perform less well tend to use a semi-Lagrangian transport scheme and/or have a very low resolution. Two models, and the multimodel mean, score consistently well on all diagnostics, while seven other models score well on all diagnostics except the seasonal cycle of water vapor. Only four of the models are consistently below average. The lack of tropospheric chemistry in most models limits their evaluation in the upper troposphere. Finally, the UTLS is relatively sparsely sampled by observations, limiting our ability to quantitatively evaluate many aspects of model performance. Copyright © 2010 by the American Geophysical Union."
"12775969000;56157920300;","A persistent wintertime fog episode at Lisbon airport (Portugal): performance of ECMWF and AROME models",2016,"10.1002/met.1560","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971491647&doi=10.1002%2fmet.1560&partnerID=40&md5=490ad5d340307ffa33b96ebabacfc77e","The 7–8 January 2015 persistent fog episode at Lisbon international airport is analysed. Its persistence was atypical of the local climate (second longest episode since 2004) and caused significant air traffic disruptions. Furthermore, the performance of two operational models (European Centre for Medium-range Weather Forecasts (ECMWF) and Applications of Research to Operations at Mesoscale (AROME)) used at the Portuguese Weather Service is assessed not only for the selected fog episode, but also for the extended winters (November to March) of 2013/2014 and 2014/2015. This episode developed under the following conditions: (1) the occurrence of a strong and persistent midwinter anticyclone over Iberia, driving favourable conditions for the formation of radiation fog; (2) a short interruption of the anticyclonic circulation by a kata-cold front on the day before, favouring the development of fog/low stratus clouds, which persisted until dawn on 7 January over the Tagus valley; (3) low-tropospheric easterly/northeasterly winds, favouring the drift of fog patches from the Tagus towards Lisbon. At the nearest grid point to Lisbon airport, both ECMWF and AROME were able to capture fog occurrence, but were unable to predict its persistence throughout the episode. Moreover, both models overestimated the 2 m temperature and dew point depression. Low cloud cover and horizontal visibility from ECMWF revealed higher skill in fog prediction than that derived from AROME. Nonetheless, a modified version of the Fog Stability Index based on AROME was proven to be a more skilful fog predictor, also outperforming other predictors based on ECMWF. These conclusions are also supported by an objective verification over a two-winter period. © 2016 Royal Meteorological Society"
"55490127200;56329651900;36110342400;55090628200;57209163758;57203140102;56820509800;","Mapping global forest aboveground biomass with spaceborne LiDAR, optical imagery, and forest inventory data",2016,"10.3390/rs8070565","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85018575318&doi=10.3390%2frs8070565&partnerID=40&md5=90c37009ea14142b1d7463263b73b514","As a large carbon pool, global forest ecosystems are a critical component of the global carbon cycle. Accurate estimations of global forest aboveground biomass (AGB) can improve the understanding of global carbon dynamics and help to quantify anthropogenic carbon emissions. Light detection and ranging (LiDAR) techniques have been proven that can accurately capture both horizontal and vertical forest structures and increase the accuracy of forest AGB estimation. In this study, we mapped the global forest AGB density at a 1-km resolution through the integration of ground inventory data, optical imagery, Geoscience Laser Altimeter System/Ice, Cloud, and Land Elevation Satellite data, climate surfaces, and topographic data. Over 4000 ground inventory records were collected from published literatures to train the forest AGB estimation model and validate the resulting global forest AGB product. Our wall-to-wall global forest AGB map showed that the global forest AGB density was 210.09 Mg/ha on average, with a standard deviation of 109.31 Mg/ha. At the continental level, Africa (333.34 ± 63.80 Mg/ha) and South America (301.68 ± 67.43 Mg/ha) had higher AGB density. The AGB density in Asia, North America and Europe were 172.28 ± 94.75, 166.48 ± 84.97, and 132.97 ± 50.70 Mg/ha, respectively. The wall-to-wall forest AGB map was evaluated at plot level using independent plot measurements. The adjusted coefficient of determination (R2) and root-mean-square error (RMSE) between our predicted results and the validation plots were 0.56 and 87.53 Mg/ha, respectively. At the ecological zone level, the R2 and RMSE between our map and Intergovernmental Panel on Climate Change suggested values were 0.56 and 101.21 Mg/ha, respectively. Moreover, a comprehensive comparison was also conducted between our forest AGB map and other published regional AGB products. Overall, our forest AGB map showed good agreements with these regional AGB products, but some of the regional AGB products tended to underestimate forest AGB density. © 2016 by the authors."
"57203492395;57189492881;34976155900;56724696200;9536598800;57217271893;56955690600;7404678955;","The interaction of moist convection and mid-level dry air in the advance of the onset of the Indian monsoon",2016,"10.1002/qj.2815","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971425593&doi=10.1002%2fqj.2815&partnerID=40&md5=4943705881ffe904a2fd8b94ecdd85a8","The advance of the onset of the Indian monsoon is here explained in terms of a balance between the low-level monsoon flow and an overrunning intrusion of mid-tropospheric dry air. The monsoon advances, over a period of about 6 weeks, from the south of the country to the northwest. Given that the low-level monsoon winds are westerly or southwesterly, and the mid-level winds northwesterly, the monsoon onset propagates upwind relative to mid-level flow, and perpendicular to the low-level flow, and is not directly caused by moisture flux toward the northwest. Lacking a conceptual model for the advance means that it has been hard to understand and correct known biases in weather and climate prediction models. The mid-level northwesterlies form a wedge of dry air that is deep in the far northwest of India and over-runs the monsoon flow. The dry layer is moistened from below by shallow cumulus and congestus clouds, so that the profile becomes much closer to moist adiabatic, and the dry layer is much shallower in the vertical, toward the southeast of India. The profiles associated with this dry air show how the most favourable environment for deep convection occurs in the south, and onset occurs here first. As the onset advances across India, the advection of moisture from the Arabian Sea becomes stronger, and the mid-level dry air is increasingly moistened from below. This increased moistening makes the wedge of dry air shallower throughout its horizontal extent, and forces the northern limit of moist convection to move toward the northwest. Wetting of the land surface by rainfall will further reinforce the north-westward progression, by sustaining the supply of boundary-layer moisture and shallow cumulus. The local advance of the monsoon onset is coincident with weakening of the mid-level northwesterlies, and therefore weakened mid-level dry advection. © 2016 The Authors. Quarterly Journal of the Royal Meteorological Society published by John Wiley & Sons Ltd on behalf of the Royal Meteorological Society."
"24338552700;8282605900;27067566200;6603357562;23134559000;6602877649;26643081200;55279353500;56472496900;23768259900;35622485500;54925973300;7004082452;55556606100;35495958000;6603816055;6602152837;","Assimilation of SMOS soil moisture and brightness temperature products into a land surface model",2016,"10.1016/j.rse.2015.10.033","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992310853&doi=10.1016%2fj.rse.2015.10.033&partnerID=40&md5=6a248aeddf2cc7603712a6b5408254ee","The Soil Moisture and Ocean Salinity (SMOS) mission has the potential to improve the predictive skill of land surface models through the assimilation of its observations. Several alternate products can be distinguished: the observed brightness temperature (TB) data at coarse scale, indirect estimates of soil moisture (SM) through the inversion of the coarse-scale TB observations, and fine-scale soil moisture through the a priori downscaling of coarse-scale soil moisture. The SMOS TB products include observations over a large range of incidence angles at both H- and V-polarizations, which allows the merit of assimilating the full set of multi-angular/polarization observations, as opposed to specific sub-sets of observations, to be assessed. This study investigates the performance of various observation scenarios with respect to soil moisture and streamflow predictions in the Murray Darling Basin. The observations are assimilated into the Variable Infiltration Capacity (VIC) model, coupled to the Community Microwave Emission Modeling (CMEM) platform, using the Ensemble Kalman filter. The assimilation of these various observation products is assessed under similar realistic assimilation settings, without optimization, and validated by comparison of the modeled soil moisture and streamflow to in situ measurements across the basin. The best results are achieved from assimilation of the coarse-scale SM observations. The reduced improvement using downscaled SM is probably due to a lower number of observations, as a result of cloud cover effects on the downscaling method. The assimilation of TB was found to be a promising alternative, which led to improvements in soil moisture prediction approaching those of the coarse-scale SM assimilation. © 2015 Elsevier Inc."
"57188634725;55663720200;","Prediction of high spatio-temporal resolution land surface temperature under cloudy conditions using microwave vegetation index and ANN",2016,"10.1016/j.isprsjprs.2016.03.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961956784&doi=10.1016%2fj.isprsjprs.2016.03.011&partnerID=40&md5=24e345cfa4914359e57eb55e22b10eda","Land Surface Temperature (LST) with high spatio-temporal resolution is in demand for hydrology, climate change, ecology, urban climate and environmental studies, etc. Moderate Resolution Imaging Spectroradiometer (MODIS) is one of the most commonly used sensors owing to its high spatial and temporal availability over the globe, but is incapable of providing LST data under cloudy conditions, resulting in gaps in the data. In contrast, microwave measurements have a capability to penetrate under clouds. The current study proposes a methodology by exploring this property to predict high spatio-temporal resolution LST under cloudy conditions during daytime and nighttime without employing in-situ LST measurements. To achieve this, Artificial Neural Networks (ANNs) based models are employed for different land cover classes, utilizing Microwave Polarization Difference Index (MPDI) at finer resolution with ancillary data. MPDI was derived using resampled (from 0.25° to 1 km) brightness temperatures (Tb) at 36.5 GHz channel of dual polarization from Advance Microwave Scanning Radiometer (AMSR)-Earth Observing System and AMSR2 sensors. The proposed methodology is tested over Cauvery basin in India and the performance of the model is quantitatively evaluated through performance measures such as correlation coefficient (r), Nash Sutcliffe Efficiency (NSE) and Root Mean Square Error (RMSE). Results revealed that during daytime, AMSR-E(AMSR2) derived LST under clear sky conditions corresponds well with MODIS LST resulting in values of r ranging from 0.76(0.78) to 0.90(0.96), RMSE from 1.76(1.86) K to 4.34(4.00) K and NSE from 0.58(0.61) to 0.81(0.90) for different land cover classes. During nighttime, r values ranged from 0.76(0.56) to 0.87(0.90), RMSE from 1.71(1.70) K to 2.43(2.12) K and NSE from 0.43(0.28) to 0.80(0.81) for different land cover classes. RMSE values found between predicted LST and MODIS LST during daytime under clear sky conditions were within acceptable limits. Under cloudy conditions, results of microwave derived LST were evaluated with air temperature (Ta) and indicate that the approach performed well with RMSE values lesser than the results obtained under clear sky conditions for land cover classes for both day and nighttimes. © 2016 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS)."
"56647481100;35262555900;23096443800;7202530955;","Characteristics and diurnal cycle of GPM rainfall estimates over the Central Amazon region",2016,"10.3390/rs8070544","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007409805&doi=10.3390%2frs8070544&partnerID=40&md5=4ef99e3c8ad49e90d5ef7f4505ca17d3","Studies that investigate and evaluate the quality, limitations and uncertainties of satellite rainfall estimates are fundamental to assure the correct and successful use of these products in applications, such as climate studies, hydrological modeling and natural hazard monitoring. Over regions of the globe that lack in situ observations, such studies are only possible through intensive field measurement campaigns, which provide a range of high quality ground measurements, e.g., CHUVA (Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GlobAl Precipitation Measurement) and GoAmazon (Observations and Modeling of the Green Ocean Amazon) over the Brazilian Amazon during 2014/2015. This study aims to assess the characteristics of Global Precipitation Measurement (GPM) satellite-based precipitation estimates in representing the diurnal cycle over the Brazilian Amazon. The Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG) and the Goddard Profiling Algorithm-Version 2014 (GPROF2014) algorithms are evaluated against ground-based radar observations. Specifically, the S-band weather radar from the Amazon Protection National System (SIPAM), is first validated against the X-band CHUVA radar and then used as a reference to evaluate GPM precipitation. Results showed satisfactory agreement between S-band SIPAM radar and both IMERG and GPROF2014 algorithms. However, during the wet season, IMERG, which uses the GPROF2014 rainfall retrieval from the GPM Microwave Imager (GMI) sensor, significantly overestimates the frequency of heavy rainfall volumes around 00:00-04:00 UTC and 15:00-18:00 UTC. This overestimation is particularly evident over the Negro, Solimões and Amazon rivers due to the poorly-calibrated algorithm over water surfaces. On the other hand, during the dry season, the IMERG product underestimates mean precipitation in comparison to the S-band SIPAM radar, mainly due to the fact that isolated convective rain cells in the afternoon are not detected by the satellite precipitation algorithm. © 2016 by the authors."
"55263525600;55458623700;6603409139;55850233200;55607266000;55573356500;7006781962;57189372185;7006204597;","Observations and implications of liquid-liquid phase separation at high relative humidities in secondary organic material produced by α-pinene ozonolysis without inorganic salts",2016,"10.5194/acp-16-7969-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977090749&doi=10.5194%2facp-16-7969-2016&partnerID=40&md5=f9d53c3bf50a455947f214b1cb73915b","Particles consisting of secondary organic material (SOM) are abundant in the atmosphere. To predict the role of these particles in climate, visibility and atmospheric chemistry, information on particle phase state (i.e., single liquid, two liquids and solid) is needed. This paper focuses on the phase state of SOM particles free of inorganic salts produced by the ozonolysis of α-pinene. Phase transitions were investigated in the laboratory using optical microscopy and theoretically using a thermodynamic model at 290 K and for relative humidities ranging from < 0.5 to 100 %. In the laboratory studies, a single phase was observed from 0 to 95 % relative humidity (RH) while two liquid phases were observed above 95 % RH. For increasing RH, the mechanism of liquid-liquid phase separation (LLPS) was spinodal decomposition. The RH range over which two liquid phases were observed did not depend on the direction of RH change. In the modeling studies, the SOM took up very little water and was a single organic-rich phase at low RH values. At high RH, the SOM underwent LLPS to form an organic-rich phase and a water-rich phase, consistent with the laboratory studies. The presence of LLPS at high RH values can have consequences for the cloud condensation nuclei (CCN) activity of SOM particles. In the simulated Köhler curves for SOM particles, two local maxima were observed. Depending on the composition of the SOM, the first or second maximum can determine the critical supersaturation for activation. Recently researchers have observed inconsistencies between measured CCN properties of SOM particles and hygroscopic growth measured below water saturation (i.e., hygroscopic parameters measured below water saturation were inconsistent with hygroscopic parameters measured above water saturation). The work presented here illustrates that such inconsistencies are expected for systems with LLPS when the water uptake at subsaturated conditions represents the hygroscopicity of an organic-rich phase while the barrier for CCN activation can be determined by the second maximum in the Köhler curve when the particles are water rich. © Author(s) 2016."
"55457441700;35362887100;36779146200;9036557400;55185043800;","Evaluating five remote sensing based single-source surface energy balance models for estimating daily evapotranspiration in a humid subtropical climate",2016,"10.1016/j.jag.2016.01.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016163936&doi=10.1016%2fj.jag.2016.01.010&partnerID=40&md5=a497fad031108a0278603391db1fd3da","In the last two decades, a number of single-source surface energy balance (SEB) models have been proposed for mapping evapotranspiration (ET); however, there is no clear guidance on which models are preferable under different conditions. In this paper, we tested five models-Surface Energy Balance Algorithm for Land (SEBAL), Mapping ET at high Resolution with Internalized Calibration (METRIC), Simplified Surface Energy Balance Index (S-SEBI), Surface Energy Balance System (SEBS), and operational Simplified Surface Energy Balance (SSEBop)—to identify the single-source SEB models most appropriate for use in the humid southeastern United States. ET predictions from these models were compared with measured ET at four sites (marsh, grass, and citrus surfaces) for 149 cloud-free Landsat image acquisition days between 2000 and 2010. The overall model evaluation statistics showed that SEBS generally outperformed the other models in terms of estimating daily ET from different land covers (e.g., the root mean squared error (RMSE) was 0.74 mm day−1). SSEBop was consistently the worst performing model and overestimated ET at all sites (RMSE = 1.67 mm day−1), while the other models typically fell in between SSEBop and SEBS. However, for short grass conditions, SEBAL, METRIC, and S-SEBI appear to work much better than SEBS. Overall, our study suggests that SEBS may be the best SEB model in humid regions, although it may require modifications to work better over short vegetation. © 2016 Elsevier B.V."
"57194399017;6603916527;6603839405;56186692400;57188723336;35565587500;8654499000;7003506210;57156407800;6602544059;57194395232;57194387303;","Mapping forest cover and forest cover change with airborne S-band radar",2016,"10.3390/rs8070577","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019918457&doi=10.3390%2frs8070577&partnerID=40&md5=3dd0ea6f827cecb04d6a3f3a3ffb5bbd","Assessments of forest cover, forest carbon stocks and carbon emissions from deforestation and degradation are increasingly important components of sustainable resource management, for combating biodiversity loss and in climate mitigation policies. Satellite remote sensing provides the only means for mapping global forest cover regularly. However, forest classification with optical data is limited by its insensitivity to three-dimensional canopy structure and cloud cover obscuring many forest regions. Synthetic Aperture Radar (SAR) sensors are increasingly being used to mitigate these problems, mainly in the L-, C- and X-band domains of the electromagnetic spectrum. S-band has not been systematically studied for this purpose. In anticipation of the British built NovaSAR-S satellite mission, this study evaluates the benefits of polarimetric S-band SAR for forest characterisation. The Michigan Microwave Canopy Scattering (MIMICS-I) radiative transfer model is utilised to understand the scattering mechanisms in forest canopies at S-band. The MIMICS-I model reveals strong S-band backscatter sensitivity to the forest canopy in comparison to soil characteristics across all polarisations and incidence angles. Airborne S-band SAR imagery over the temperate mixed forest of Savernake Forest in southern England is analysed for its information content. Based on the modelling results, S-band HH- and VV-polarisation radar backscatter and the Radar Forest Degradation Index (RFDI) are used in a forest/non-forest Maximum Likelihood classification at a spatial resolution of 6 m (70% overall accuracy, κ = 0.41) and 20 m (63% overall accuracy, κ = 0.27). The conclusion is that S-band SAR such as from NovaSAR-S is likely to be suitable for monitoring forest cover and its changes. © 2016 by the authors."
"36951571000;35090697300;55988964600;49361390400;55715044700;","Variation of cloud amount over China and the relationship with ENSO from 1951 to 2014",2016,"10.1002/joc.4529","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976482791&doi=10.1002%2fjoc.4529&partnerID=40&md5=d4108299dc424a03022f877124c3a854","In this study, the climatic trend of the total cloud amount (TCA) and the low cloud amount (LCA) was studied using climate diagnostic methods while the correlations and possible physical mechanism between TCA, LCA and El Niño and Southern Oscillation (ENSO) were analysed and discussed. The results indicated that the annual average TCA and LCA reduced with increasing latitude while a significant decreasing trend has been derived for TCA and LCA; the trend rate is 0.9% per decade and 0.2% per decade, respectively. Moreover, the most obvious reduction area of TCA was focused in Northeast China and for LCA, it was located in the surrounding area of the Shaanxi province. The cloud amounts of the four seasons also showed a reducing tendency except the LCA of summer. Meanwhile, the spectrum analysis showed that TCA has 10, 5.7, 3.6 and 2.8 year periods and LCA has 10, 4, 2.7 and 2.1 year-long time cycles. Further analysis also revealed that the annual average TCA has a significant negative correlation with ENSO, and the most remarkable negative correlation centre is focused on central China. However, the relationship of the annual average LCA with ENSO is relatively weak. Except in spring, the spatial correlation distribution of TCA and LCA with ENSO in the other seasons was consistent with that of the annual average TCA and LCA, and 4-year periods of TCA and LCA coincide with the cycle of ENSO. This reveals that ENSO has an impact on inter-annual variations of TCA and LCA over China. It is generally considered that ENSO, through the atmospheric circulation situation, causes variation of cloud amounts. © 2015 Royal Meteorological Society"
"7006237834;","Climate Sensitivity in the Geologic Past",2016,"10.1146/annurev-earth-100815-024150","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977147327&doi=10.1146%2fannurev-earth-100815-024150&partnerID=40&md5=f888570aabfc908dd8d95633892434e4","The response of temperature to CO2 change (climate sensitivity) in the geologic past may help inform future climate predictions. Proxies for CO2 and temperature generally imply high climate sensitivities: ≥3 K per CO2 doubling during ice-free times (fast-feedback sensitivity) and ≥6 K during times with land ice (Earth-system sensitivity). Climate models commonly underpredict the magnitude of climate change and have fast-feedback sensitivities close to 3 K. A better characterization of feedbacks in warm worlds raises climate sensitivity to values more in line with proxies and produces climate simulations that better fit geologic evidence. As CO2 builds in our atmosphere, we should expect both slow (e.g., land ice) and fast (e.g., vegetation, clouds) feedbacks to elevate the long-term temperature response over that predicted from the canonical fast-feedback value of 3 K. Because temperatures will not decline for centuries to millennia, climate sensitivities that integrate slower processes have relevance for current climate policy. Copyright © 2016 by Annual Reviews. All rights reserved."
"56543138800;57202142004;6701313597;7003427471;7003430284;57190001768;57208121047;56592889000;36194896400;56452429200;16444265000;8058018000;57190004884;55730602600;57203231853;7004027519;","Ship emissions measurement in the Arctic by plume intercepts of the Canadian Coast Guard icebreaker Amundsen from the Polar 6 aircraft platform",2016,"10.5194/acp-16-7899-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977140485&doi=10.5194%2facp-16-7899-2016&partnerID=40&md5=2ab22e7f7fb5928d39df79444fe9f1e4","Decreasing sea ice and increasing marine navigability in northern latitudes have changed Arctic ship traffic patterns in recent years and are predicted to increase annual ship traffic in the Arctic in the future. Development of effective regulations to manage environmental impacts of shipping requires an understanding of ship emissions and atmospheric processing in the Arctic environment. As part of the summer 2014 NETCARE (Network on Climate and Aerosols) campaign, the plume dispersion and gas and particle emission factors of effluents originating from the Canadian Coast Guard icebreaker Amundsen operating near Resolute Bay, NU, Canada, were investigated. The Amundsen burned distillate fuel with 1.5 wt % sulfur. Emissions were studied via plume intercepts using the Polar 6 aircraft measurements, an analytical plume dispersion model, and using the FLEXPART-WRF Lagrangian particle dispersion model. The first plume intercept by the research aircraft was carried out on 19 July 2014 during the operation of the Amundsen in the open water. The second and third plume intercepts were carried out on 20 and 21 July 2014 when the Amundsen had reached the ice edge and operated under ice-breaking conditions. Typical of Arctic marine navigation, the engine load was low compared to cruising conditions for all of the plume intercepts. The measured species included mixing ratios of CO2, NOx, CO, SO2, particle number concentration (CN), refractory black carbon (rBC), and cloud condensation nuclei (CCN). The results were compared to similar experimental studies in mid-latitudes. Plume expansion rates (γ) were calculated using the analytical model and found to be γ = 0.75 ± 0.81, 0.93 ± 0.37, and 1.19 ± 0.39 for plumes 1, 2, and 3, respectively. These rates were smaller than prior studies conducted at mid-latitudes, likely due to polar boundary layer dynamics, including reduced turbulent mixing compared to mid-latitudes. All emission factors were in agreement with prior observations at low engine loads in mid-latitudes. Ice-breaking increased the NOx emission factor from EFNOx = 43.1 ± 15.2 to 71.6 ± 9.68 and 71.4 ± 4.14 g kg-diesel-1 for plumes 1, 2, and 3, likely due to changes in combustion temperatures. The CO emission factor was EFCO = 137 ± 120, 12.5 ± 3.70 and 8.13 ± 1.34 g kg-diesel-1 for plumes 1, 2, and 3. The rBC emission factor was EFrBC = 0.202 ± 0.052 and 0.202 ± 0.125 g kg-diesel-1 for plumes 1 and 2. The CN emission factor was reduced while ice-breaking from EFCN = 2.41 ± 0.47 to 0.45 ± 0.082 and 0.507 ± 0.037 × 1016 kg-diesel-1 for plumes 1, 2, and 3. At 0.6 % supersaturation, the CCN emission factor was comparable to observations in mid-latitudes at low engine loads with EFCCN = 3.03 ± 0.933, 1.39 ± 0.319, and 0.650 ± 0.136 × 1014 kg-diesel-1 for plumes 1, 2, and 3."
"15050523700;15047538100;6602135370;36242447900;","Indian summer monsoon precipitating clouds: Role of microphysical process rates",2016,"10.1007/s00382-015-2717-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84933056058&doi=10.1007%2fs00382-015-2717-8&partnerID=40&md5=d2f89ed2191472c89ff86644c921d532","The budget analysis of microphysical process rates based on Modern Era Retrospective-analysis for Research and Applications (MERRA) products are presented in the study. The relative importance of different microphysical process rates, which is crucial for GCMs, is investigated. The autoconversion and accretion processes are found to be vital for Indian Summer Monsoon (ISM). The map-to-map correlations are examined between observed precipitation and MERRA reanalysis. The pattern correlations connote the fidelity of the MERRA datasets used here. Results of other microphysical parameters (e.g. ice water content from CloudSat, high cloud fraction from CALIPSO and MODIS, latent heating from TRMM, cloud ice mixing ratio from MERRA) are presented in this study. The tropospheric temperature from reanalysis product of MERRA and NCEP are also analyzed. Furthermore, the linkages between cloud microphysics production rates and dynamics, which are important for North-South tropospheric temperature gradient for maintaining the ISM circulation, are also discussed. The study demonstrates the microphysical process rates, which are actually responsible for the cloud hydrometeors and precipitation formation on the monsoon intraseasonal oscillations timescale. Cloud to rain water auto-conversion and snow accretion rates are the dominant processes followed by the rain accretion. All these tendency terms replicates the similar spatial patterns as that of precipitation. The quantification of microphysical process rates and precipitation over different regions are shown here. The freezing rate is also imperative for the formation of cloud ice as revealed by the observation. Freezing rates at upper level and snow accretion at middle level may have effect on latent heating release. Further it can modulate the north-south temperature gradient which can influence the large-scale monsoon dynamics. The rain water evaporation is also considered as a key aspect for controlling the low level moisture convergence (source of water vapor) in ISM. This study has highlighted the importance of detailed microphysical production rates for warm and mixed-phase cloud processes, which is a major source of uncertainty in the climate models. Better understanding of these processes will definitely add value to the present generation climate models. Therefore the hypothesis/pathway emerged from the present study may be helpful for the future model development research. © Springer-Verlag Berlin Heidelberg 2015."
"56452429200;36194896400;57202142004;57190004884;55730602600;16444265000;8058018000;56543138800;57190001768;6701313597;7003430284;7004027519;","Growth of nucleation mode particles in the summertime Arctic: A case study",2016,"10.5194/acp-16-7663-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976449484&doi=10.5194%2facp-16-7663-2016&partnerID=40&md5=c58d38d25adc5116196a0b05166841e5","The summertime Arctic lower troposphere is a relatively pristine background aerosol environment dominated by nucleation and Aitken mode particles. Understanding the mechanisms that control the formation and growth of aerosol is crucial for our ability to predict cloud properties and therefore radiative balance and climate. We present an analysis of an aerosol growth event observed in the Canadian Arctic Archipelago during summer as part of the NETCARE project. Under stable and clean atmospheric conditions, with low inversion heights, carbon monoxide less than 80 ppbv, and black carbon less than 5 ng m-3, we observe growth of small particles, &lt; 20 nm in diameter, into sizes above 50 nm. Aerosol growth was correlated with the presence of organic species, trimethylamine, and methanesulfonic acid (MSA) in particles ∼ 80 nm and larger, where the organics are similar to those previously observed in marine settings. MSA-to-sulfate ratios as high as 0.15 were observed during aerosol growth, suggesting an important marine influence. The organic-rich aerosol contributes significantly to particles active as cloud condensation nuclei (CCN, supersaturation = 0.6 %), which are elevated in concentration during aerosol growth above background levels of ∼ 100 to ∼ 220 cm-3. Results from this case study highlight the potential importance of secondary organic aerosol formation and its role in growing nucleation mode aerosol into CCN-active sizes in this remote marine environment. © 2016 Author(s)."
"7003800456;57190047135;8263760800;35338710200;55519833300;57190048278;","Sulfate aerosols from non-explosive volcanoes: Chemical-radiative effects in the troposphere and lower stratosphere",2016,"10.3390/atmos7070085","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982813048&doi=10.3390%2fatmos7070085&partnerID=40&md5=252455b600aa6d014f478bb6dc1b83bc","SO2 and H2S are the two most important gas-phase sulfur species emitted by volcanoes, with a global amount from non-explosive emissions of the order 10 Tg-S/yr. These gases are readily oxidized forming SO4 2- aerosols, which effectively scatter the incoming solar radiation and cool the surface. They also perturb atmospheric chemistry by enhancing the NOx to HNO3 heterogeneous conversion via hydrolysis on the aerosol surface of N2O5 and Br-Cl nitrates. This reduces formation of tropospheric O3 and the OH to HO2 ratio, thus limiting the oxidation of CH4 and increasing its lifetime. In addition to this tropospheric chemistry perturbation, there is also an impact on the NOx heterogeneous chemistry in the lower stratosphere, due to vertical transport of volcanic SO2 up to the tropical tropopause layer. Furthermore, the stratospheric O3 formation and loss, as well as the NOx budget, may be slightly affected by the additional amount of upward diffused solar radiation and consequent increase of photolysis rates. Two multi-decadal time-slice runs of a climate-chemistry-aerosol model have been designed for studying these chemical-radiative effects. A tropopause mean global net radiative flux change (RF) of -0.23 W·m-2 is calculated (including direct and indirect aerosol effects) with a 14% increase of the global mean sulfate aerosol optical depth. A 5-15 ppt NOx decrease is found in the mid-troposphere subtropics and mid-latitudes and also from pole to pole in the lower stratosphere. The tropospheric NOx perturbation triggers a column O3 decrease of 0.5-1.5 DU and a 1.1% increase of the CH4 lifetime. The surface cooling induced by solar radiation scattering by the volcanic aerosols induces a tropospheric stabilization with reduced updraft velocities that produce ice supersaturation conditions in the upper troposphere. A global mean 0.9% decrease of the cirrus ice optical depth is calculated with an indirect RF of -0.08 Wcm-2."
"14630194200;6602080205;37056101400;","A case study of the radiative effect of aerosols over Europe: EUCAARI-LONGREX",2016,"10.5194/acp-16-7639-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976271625&doi=10.5194%2facp-16-7639-2016&partnerID=40&md5=c6640e84e6314936190ed0e001e439be","The radiative effect of anthropogenic aerosols over Europe during the 2008 European Integrated Project on Aerosol Cloud Climate and Air Quality Interactions Long Range Experiment (EUCAARI-LONGREX) campaign has been calculated using measurements collected by the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft and radiative transfer modelling. The aircraft sampled anthropogenically perturbed air masses across north-western Europe under anticyclonic conditions with aerosol optical depths ranging from 0.047 to 0.357. For one specially designed ""radiative closure"" flight, simulated irradiances have been compared to radiation measurements for a case of aged European aerosol in order to explore the validity of model assumptions and the degree of radiative closure that can be attained given the spatial and temporal variability of the observations and their measurement uncertainties. Secondly, the diurnally averaged aerosol radiative effect throughout EUCAARI-LONGREX has been calculated. The surface radiative effect ranged between -3.9 and -22.8Wm-2 (mean -11±5Wm-2), whilst top-of-the-atmosphere (TOA) values were between -2.1 and -12.0Wm-2 (mean -5±3Wm-2). We have quantified the uncertainties in our calculations due to the way in which aerosols and other parameters are represented in a radiative transfer model. The largest uncertainty in the aerosol radiative effect at both the surface and the TOA comes from the spectral resolution of the information used in the radiative transfer model (∼ 17%) and the aerosol description (composition and size distribution) used in the Mie calculations of the aerosol optical properties included in the radiative transfer model (∼7%). The aerosol radiative effect at the TOA is also highly sensitive to the surface albedo (∼12%). © Author(s) 2016."
"55479830300;55469200300;22954523900;7003314595;7202607188;57201124395;7102011023;","Climatological and radiative properties of midlatitude cirrus clouds derived by automatic evaluation of lidar measurements",2016,"10.5194/acp-16-7605-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975885867&doi=10.5194%2facp-16-7605-2016&partnerID=40&md5=55520e10c88618b8233911ae16b1a7be","Cirrus, i.e., high, thin clouds that are fully glaciated, play an important role in the Earth's radiation budget as they interact with both long- and shortwave radiation and affect the water vapor budget of the upper troposphere and stratosphere. Here, we present a climatology of midlatitude cirrus clouds measured with the same type of ground-based lidar at three midlatitude research stations: at the Swiss high alpine Jungfraujoch station (3580ma.s.l.), in Zürich (Switzerland, 510ma.s.l.), and in Jülich (Germany, 100ma.s.l.). The analysis is based on 13000h of measurements from 2010 to 2014. To automatically evaluate this extensive data set, we have developed the Fast LIdar Cirrus Algorithm (FLICA), which combines a pixel-based cloud-detection scheme with the classic lidar evaluation techniques. We find mean cirrus optical depths of 0.12 on Jungfraujoch and of 0.14 and 0.17 in Zürich and Jülich, respectively. Above Jungfraujoch, subvisible cirrus clouds (τ, &lt; 0.03) have been observed during 6% of the observation time, whereas above Zürich and Jülich fewer clouds of that type were observed. Cirrus have been observed up to altitudes of 14.4kma.s.l. above Jungfraujoch, whereas they have only been observed to about 1km lower at the other stations. These features highlight the advantage of the high-altitude station Jungfraujoch, which is often in the free troposphere above the polluted boundary layer, thus enabling lidar measurements of thinner and higher clouds. In addition, the measurements suggest a change in cloud morphology at Jungfraujoch above ~ 13km, possibly because high particle number densities form in the observed cirrus clouds, when many ice crystals nucleate in the high supersaturations following rapid uplifts in lee waves above mountainous terrain. The retrieved optical properties are used as input for a radiative transfer model to estimate the net cloud radiative forcing, CRFNET, for the analyzed cirrus clouds. All cirrus detected here have a positive CRFNET. This confirms that these thin, high cirrus have a warming effect on the Earth's climate, whereas cooling clouds typically have cloud edges too low in altitude to satisfy the FLICA criterion of temperatures below -38°C. We find CRFNET Combining double low line 0.9Wm-2 for Jungfraujoch and 1.0Wm-2 (1.7Wm-2) for Zürich (Jülich). Further, we calculate that subvisible cirrus (Ï., &amp;lt; 0.03) contribute about 5%, thin cirrus (0.03 &lt; τ, &lt; 0.3) about 45%, and opaque cirrus (0.3 &lt; τ) about 50% of the total cirrus radiative forcing. © Author(s) 2016."
"56074832600;57189904212;36482925800;","Study on solar radiation models in South Korea for improving office building energy performance analysis",2016,"10.3390/su8060589","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975801395&doi=10.3390%2fsu8060589&partnerID=40&md5=85864bbcde37374ad79378a29b933feb","Hourly global solar radiation in a weather file is one of the significant parameters for improving building energy performance analyses using simulation programs. However, most weather stations worldwide are not equipped with solar radiation sensors because they tend to be difficult to manage. In South Korea, only twenty-two out of ninety-two weather stations are equipped with sensors, and there are large areas not equipped with any sensors. Thus, solar radiation must often be calculated by reliable solar models. Hence, it is important to find a reliable model that can be applied in the wide variety of weather conditions seen in South Korea. In this study, solar radiation in the southeastern part of South Korea was calculated using three solar models: cloud-cover radiation model (CRM), Zhang and Huang model (ZHM), and meteorological radiation model (MRM). These values were then compared to measured solar radiation data. After that, the calculated solar radiation data from the three solar models were used in a building energy simulation for an office building with various window characteristics conditions, in order to identify how solar radiation differences affect building energy performance. It was found that a seasonal solar model for the area should be developed to improve building energy performance analysis. © 2016 by the authors."
"36553486200;55656837900;57196143493;","Strong modification of stratospheric ozone forcing by cloud and sea-ice adjustments",2016,"10.5194/acp-16-7559-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975483333&doi=10.5194%2facp-16-7559-2016&partnerID=40&md5=f56dd6d09ac5d3dac35211442e8f4f8f","We investigate the climatic impact of stratospheric ozone recovery (SOR), with a focus on the surface temperature change in atmosphere-slab ocean coupled climate simulations. We find that although SOR would cause significant surface warming (global mean: 0.2ĝ€K) in a climate free of clouds and sea ice, it causes surface cooling (ĝ'0.06ĝ€K) in the real climate. The results here are especially interesting in that the stratosphere-adjusted radiative forcing is positive in both cases. Radiation diagnosis shows that the surface cooling is mainly due to a strong radiative effect resulting from significant reduction of global high clouds and, to a lesser extent, from an increase in high-latitude sea ice. Our simulation experiments suggest that clouds and sea ice are sensitive to stratospheric ozone perturbation, which constitutes a significant radiative adjustment that influences the sign and magnitude of the global surface temperature change. © Author(s) 2016."
"55158800800;35376447600;7102578937;","Evaluation of SCIAMACHY ESA/DLR cloud parameters version 5.02 by Comparisons to Ground-Based and Other satellite data",2016,"10.3389/fenvs.2016.00043","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85040784638&doi=10.3389%2ffenvs.2016.00043&partnerID=40&md5=c82a4654f1c645846663bf73367220f5","This paper reports on the evaluation of long-term cloud products as retrieved from measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) instrument with the DLR/ESA processor in its version 5.02 and the operational implementation of the Semi-Analytical CloUd Retrieval Algorithm SACURA. The comparison is performed against spaceborne and ground-based cloud data. The satellite records are the SCIAMACHY/SACURA in its scientific implementation and the Global retrieval of ATSR cloud parameters and evaluation (GRAPE) data set, in its version 3.2, generated for the nadir view of the Advanced Along-Track Scanning Radiometer (AATSR) instrument onboard ENVISAT. Ground-based data are derived from profiles of micro-pulse lidars, continuously operated at three Atmospheric Radiation Measurement (ARM) research facilities. They are, namely, North Slope Alaska, Southern Great Plains and Tropical Western Pacific-Nauru, located in three different latitude belts. It has been found that SCIAMACHY cloud top heights, inferred in the visible-near infrared, have a seasonal dependent overestimation in range 0.6-1.0 km when compared to the thermal infrared-derived AATSR cloud top heights. The comparison with the in-situ cloud retrievals reveals that SCIAMACHY cloud altitudes are more accurate for local cloud cover values > 0.6. © 2016 Lelli, Weber and Burrows."
"57192695511;55782855600;56971076700;57214355992;57213723047;6505786772;9241757800;6507046956;6603640779;55694391900;55638979500;","A multi-sensor view of the 2012 central plains drought from space",2016,"10.3389/fenvs.2016.00045","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020934681&doi=10.3389%2ffenvs.2016.00045&partnerID=40&md5=352b840c54ec1fc7221c3c4238440552","In summer of 2012, the Central Plains of the United States experienced its most severe drought since the ground-based data record began in the late 1900s. By using comprehensive satellite data from MODIS (Moderate Resolution Imaging Spectroradiometer) and TRMM (Tropical Rainfall Measuring Mission), along with in-situ observations, this study documents the geophysical parameters associated with this drought, and thereby providing, for the first time, a large-scale observation-based view of the extent to which the land surface temperature and vegetation can likely be affected by both the severe drought and the agricultural response (irrigation) to the drought. Over non-irrigated area, 2012 summer daytime land surface temperature (LST), and Normalized Difference Vegetation Index (NDVI) monthly anomalies (with respect to climate in 2002-2011) are often respectively greater than 5 K and negative, with some extreme values of 10 K and -0.2 (i.e., no green vegetation). In contrast, much smaller anomalies (< 2 K) of LST and nearly the same NDVI are found over irrigated areas. Precipitation received was an average of 5.2 cm less, while both fire counts and fire radiative power were doubled, thus contributing in part to a nearly 100% increase of aerosol optical depth in many forested areas (close to intermountain west). Water vapor amount, while decreased over the southern part, indeed slightly increased in the northern part of Central Plains. As expected, cloud fraction anomaly is negative in the entire Central Plains; however, the greatest reduction of cloud fraction is found over the irrigated areas, which is in contrast to past modeling studies showing that more irrigation, because of its impact on LST, may lead to increase of cloud fraction. © 2016 Wang, Kessner, Aegerter, Sharma, Judd, Wardlow, You, Shulski, Irmak, Kilic and Zeng."
"25227357000;7402270607;6602628253;7102018821;","A GCM investigation of dust aerosol impact on the regional climate of North Africa and South/East Asia",2016,"10.1007/s00382-015-2706-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84931397683&doi=10.1007%2fs00382-015-2706-y&partnerID=40&md5=7d72b17d9546fd71182a674a0b2b1589","The climatic effects of dust aerosols in North Africa and South/East Asia have been investigated using an atmospheric general circulation model, NCEP/GCM/SSiB (Simplified Simple Biosphere Model) and the three-dimensional aerosol data simulated by the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model. GCM simulations show that due to the scattering and absorption of solar radiation by dust particles, surface temperature decreases over both regions, accompanied by a reduced sensible heat flux. However, precipitation responses are different in these two regions. Due to differences in dust location and the associated heating with respect to the rainfall band and circulation, the effect of dust could either enhance or suppress precipitation. Over the North Africa region where dust particles are mainly located to the north of rainfall band, heating of the air column by dust particles forces a stronger ascent motion over dust layers, which induces an anomalous subsidence (or a weakened upward motion) and suppressed cyclonic circulation to its south where precipitation reduces. Furthermore, both humidity and cloud decrease due to the heating in the middle troposphere (semi-direct effect). In South/East Asia, dust particles are located in the upper troposphere over the major rainfall band during the monsoon season, especially Southwest India and the coastal area of Bay of Bengal. Heating of the air column increases upward motion and strengthens cyclonic circulation. Humidity also increases due to the draw-in of the low level moist air. Therefore, cloud and precipitation increase over South/East Asia associated with dust effect. During the pre-monsoon season, when dust particles are located to the north of the monsoon rainfall band, the heating effect results in shifting precipitation northward. The heating of air column due to dust particles, not surface cooling, plays the major role in precipitation changes. The anomalous upward motion over dust regions will induce a subsidence to its south and subsequently reduce precipitation over that region. Therefore, the responses of circulation and precipitation to aerosol forcing depend on the relative location of dust aerosols with respect to rainfall band, which may explain the fact that contradictory results exist regarding whether the aerosol effect would enhance or suppress precipitation. The dust induced change in precipitation is actually more of redistribution rather than the simple action of increase or decrease. © Springer-Verlag Berlin Heidelberg 2015."
"56439201600;24765842200;6701636816;35775264900;","The impact of lightning on tropospheric ozone chemistry using a new global lightning parametrisation",2016,"10.5194/acp-16-7507-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975517621&doi=10.5194%2facp-16-7507-2016&partnerID=40&md5=a5ad0ce056a9e73d9b76e5bc52d4faa1","A lightning parametrisation based on upward cloud ice flux is implemented in a chemistry-climate model (CCM) for the first time. The UK Chemistry and Aerosols model is used to study the impact of these lightning nitric oxide (NO) emissions on ozone. Comparisons are then made between the new ice flux parametrisation and the commonly used, cloud-top height parametrisation. The ice flux approach improves the simulation of lightning and the temporal correlations with ozone sonde measurements in the middle and upper troposphere. Peak values of ozone in these regions are attributed to high lightning NO emissions. The ice flux approach reduces the overestimation of tropical lightning apparent in this CCM when using the cloud-top approach. This results in less NO emission in the tropical upper troposphere and more in the extratropics when using the ice flux scheme. In the tropical upper troposphere the reduction in ozone concentration is around 5-10%. Surprisingly, there is only a small reduction in tropospheric ozone burden when using the ice flux approach. The greatest absolute change in ozone burden is found in the lower stratosphere, suggesting that much of the ozone produced in the upper troposphere is transported to higher altitudes. Major differences in the frequency distribution of flash rates for the two approaches are found. The cloud-top height scheme has lower maximum flash rates and more mid-range flash rates than the ice flux scheme. The initial Ox (odd oxygen species) production associated with the frequency distribution of continental lightning is analysed to show that higher flash rates are less efficient at producing Ox; low flash rates initially produce around 10 times more Ox per flash than high-end flash rates. We find that the newly implemented lightning scheme performs favourably compared to the cloud-top scheme with respect to simulation of lightning and tropospheric ozone. This alternative lightning scheme shows spatial and temporal differences in ozone chemistry which may have implications for comparison between models and observations, as well as for simulation of future changes in tropospheric ozone. © Author(s) 2016."
"6602242916;57188757856;6603641900;6701607011;55957098300;6603886699;24821258400;57196496271;7003754416;55968350800;15520751200;14019498900;","Analysis of the diurnal cycles for a better understanding of the mean annual cycle of forests greenness in Central Africa",2016,"10.1016/j.agrformet.2016.04.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962861447&doi=10.1016%2fj.agrformet.2016.04.005&partnerID=40&md5=dcf585440290e8d3a311994174966d0e","Central Africa hosts the world's second largest tropical forest after the Amazonian basin. However, as compared to its Amazonian counterpart, the Central Africa forests receive much less rain (~1500 mm/year in mean spread over two rainy seasons in March-May and September-November, and two dry seasons). They also experience a slower deforestation rate, so that the main threat for the next decades might come from climate variations. Nonetheless, their response to the annual cycle of solar radiation and rainfall/clouds is still poorly known. Analysing high resolution remote sensing data of Enhanced Vegetation Index, rainfall, cloudiness, and solar radiation for a target region located between 0 and 5°N and 12-19°E, we explore the climatic drivers of the forests greenness mean annual cycle. Three main points emerge; first, the diurnal cycle is a key-scale for understanding the mean annual cycles of rainfall and incoming solar radiation at surface, then how climate shapes the greenness mean annual evolution; second, neither the two dry seasons nor the two rainy seasons resemble each other in terms of cloud cover, solar radiation and rainfall, and their links with greenness levels; third, whereas the first rainy season (March-May) appears optimal for greenness especially because of favorable light conditions, water availability is the main controlling factor during the main dry season and at the start of the first vegetative season (February). Regarding the little dry season (mid-June-mid-August) and the second rainy season (September-October), light availability might be the main limiting factor. These findings pave the way for further studies of the climate interannual variability and change impacts on the Central Africa forests, taking into account time-scale interactions. © 2016 Elsevier B.V.."
"37090362900;6603749963;9636594900;7004942632;10139397300;","Regional emission metrics for short-lived climate forcers from multiple models",2016,"10.5194/acp-16-7451-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975077459&doi=10.5194%2facp-16-7451-2016&partnerID=40&md5=708b3bd7c1c9deca3fa6e2dbddc8f10c","For short-lived climate forcers (SLCFs), the impact of emissions depends on where and when the emissions take place. Comprehensive new calculations of various emission metrics for SLCFs are presented based on radiative forcing (RF) values calculated in four different (chemical-transport or coupled chemistry-climate) models. We distinguish between emissions during summer (May-October) and winter (November-April) for emissions in Europe and East Asia, as well as from the global shipping sector and global emissions. The species included in this study are aerosols and aerosol precursors (BC, OC, SO2, NH3), as well as ozone precursors (NOx, CO, VOCs), which also influence aerosols to a lesser degree. Emission metrics for global climate responses of these emissions, as well as for CH4, have been calculated using global warming potential (GWP) and global temperature change potential (GTP), based on dedicated RF simulations by four global models. The emission metrics include indirect cloud effects of aerosols and the semi-direct forcing for BC. In addition to the standard emission metrics for pulse and sustained emissions, we have also calculated a new emission metric designed for an emission profile consisting of a ramping period of 15 years followed by sustained emissions, which is more appropriate for a gradual implementation of mitigation policies. For the aerosols, the emission metric values are larger in magnitude for emissions in Europe than East Asia and for summer than winter. A variation is also observed for the ozone precursors, with largest values for emissions in East Asia and winter for CO and in Europe and summer for VOCs. In general, the variations between the emission metrics derived from different models are larger than the variations between regions and seasons, but the regional and seasonal variations for the best estimate also hold for most of the models individually. Further, the estimated climate impact of an illustrative mitigation policy package is robust even when accounting for the fact that the magnitude of emission metrics for different species in a given model is correlated. For the ramping emission metrics, the values are generally larger than for pulse or sustained emissions, which holds for all SLCFs. For SLCFs mitigation policies, the dependency of metric values on the region and season of emission should be considered. © 2016 Author(s)."
"56182620500;7401796996;8629713500;","Evaluation and intercomparison of clouds, precipitation, and radiation budgets in recent reanalyses using satellite-surface observations",2016,"10.1007/s00382-015-2693-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84930813268&doi=10.1007%2fs00382-015-2693-z&partnerID=40&md5=1da5f63bc9ab56fd009a5ee4f02be020","Atmospheric reanalysis datasets offer a resource for investigating climate processes and extreme events; however, their uncertainties must first be addressed. In this study, we evaluate the five reanalyzed (20CR, CFSR, Era-Interim, JRA-25, and MERRA) cloud fraction (CF), precipitation rates (PR), and top-of-atmosphere (TOA) and surface radiation budgets using satellite observations during the period 03/2000–02/2012. Compared to the annual averaged CF of 56.7 % from CERES MODIS (CM) four of the five reanalyses underpredict CFs by 1.7– 4.6 %, while 20CR overpredicts this result by 7.4 %. PR from the Tropical Rainfall Measurement Mission (TRMM) is 3.0 mm/day and the reanalyzed PRs agree with TRMM within 0.1–0.6 mm/day. The shortwave (SW) and longwave (LW) TOA cloud radiative effects (CREtoa) calculated by CERES EBAF (CE) are −48.1 and 27.3 W/m2, respectively, indicating a net cooling effect of −20.8 W/m2. Of the available reanalysis results, the CFSR and MERRA calculated net CREtoa values agree with CE within 1 W/m2, while the JRA-25 result is ~10 W/m2 more negative than the CE result, predominantly due to the underpredicted magnitude of the LW warming in the JRA-25 reanalysis. A regime metric is developed using the vertical motion field at 500 hPa over the oceans. Aptly named the “ascent” and “descent” regimes, these areas are distinguishable in their characteristic synoptic patterns and the predominant cloud-types; convective-type clouds and marine boundary layer (MBL) stratocumulus clouds. In general, clouds are overpredicted (underpredicted) in the ascent (descent) regime and the biases are often larger in the ascent regime than in the descent regime. PRs are overpredicted in both regimes; however the observed and reanalyzed PRs over the ascent regime are an order of magnitude larger than those over the descent regime, indicating different types of clouds exist in these two regimes. Based upon the Atmospheric Radiation Measurement Program ground-based and CM satellite observations, as well as reanalyzed results, the annual CFs are 15 % higher at the Azores site than at the Nauru site (70.2 vs. 55.2 %), less SW radiation (~20 %) is transmitted the surface, and less LW radiation (~60 W/m2) is emitted back to the surface. Also, the seasonal variations in both CF and surface radiation fluxes are much smaller at the Nauru site than at the Azores site. The dichotomy between the atmospheric ascent and descent regimes is a good measure for determining which parameterization scheme requires more improvement (convective vs. MBL clouds) in these five reanalyses. © Springer-Verlag Berlin Heidelberg 2015."
"26424130900;14019543900;7004167838;6602497877;6506594339;","Precipitation and microphysical processes observed by three polarimetric X-band radars and ground-based instrumentation during HOPE",2016,"10.5194/acp-16-7105-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84974803107&doi=10.5194%2facp-16-7105-2016&partnerID=40&md5=9172ff810d9a072f0b4acf16a165dc27","This study presents a first analysis of precipitation and related microphysical processes observed by three polarimetric X-band Doppler radars (BoXPol, JuXPol and KiXPol) in conjunction with a ground-based network of disdrometers, rain gauges and vertically pointing micro rain radars (MRRs) during the High Definition Clouds and Precipitation for advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE) during April and May 2013 in Germany. While JuXPol and KiXPol were continuously observing the central HOPE area near Forschungszentrum Jülich at a close distance, BoXPol observed the area from a distance of about 48.5km. MRRs were deployed in the central HOPE area and one MRR close to BoXPol in Bonn, Germany. Seven disdrometers and three rain gauges providing point precipitation observations were deployed at five locations within a 5km × 5km region, while three other disdrometers were collocated with the MRR in Bonn. The daily rainfall accumulation at each rain gauge/disdrometer location estimated from the three X-band polarimetric radar observations showed very good agreement. Accompanying microphysical processes during the evolution of precipitation systems were well captured by the polarimetric X-band radars and corroborated by independent observations from the other ground-based instruments. © Author(s) 2016."
"10739072200;6603478665;42662973900;6602493466;57204496157;34568413600;","Continental anthropogenic primary particle number emissions",2016,"10.5194/acp-16-6823-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84970992144&doi=10.5194%2facp-16-6823-2016&partnerID=40&md5=d823ed255d9dff47ba31ccb783f4140b","Atmospheric aerosol particle number concentrations impact our climate and health in ways different from those of aerosol mass concentrations. However, the global, current and future anthropogenic particle number emissions and their size distributions are so far poorly known. In this article, we present the implementation of particle number emission factors and the related size distributions in the GAINS (Greenhouse Gas-Air Pollution Interactions and Synergies) model. This implementation allows for global estimates of particle number emissions under different future scenarios, consistent with emissions of other pollutants and greenhouse gases. In addition to determining the general particulate number emissions, we also describe a method to estimate the number size distributions of the emitted black carbon particles. The first results show that the sources dominating the particle number emissions are different to those dominating the mass emissions. The major global number source is road traffic, followed by residential combustion of biofuels and coal (especially in China, India and Africa), coke production (Russia and China), and industrial combustion and processes. The size distributions of emitted particles differ across the world, depending on the main sources: in regions dominated by traffic and industry, the number size distribution of emissions peaks in diameters range from 20 to 50 nm, whereas in regions with intensive biofuel combustion and/or agricultural waste burning, the emissions of particles with diameters around 100 nm are dominant. In the baseline (current legislation) scenario, the particle number emissions in Europe, Northern and Southern Americas, Australia, and China decrease until 2030, whereas especially for India, a strong increase is estimated. The results of this study provide input for modelling of the future changes in aerosol-cloud interactions as well as particle number related adverse health effects, e.g. in response to tightening emission regulations. However, there are significant uncertainties in these current emission estimates and the key actions for decreasing the uncertainties are pointed out. © Author(s) 2016."
"23013131500;6603943978;8602890000;24777788700;16443826700;6701705691;6701607011;56271306100;8403728600;6508390183;57189659659;7004962346;7003372226;56257109300;","Synergistic use of Lagrangian dispersion and radiative transfer modelling with satellite and surface remote sensing measurements for the investigation of volcanic plumes: The Mount Etna eruption of 25-27 October 2013",2016,"10.5194/acp-16-6841-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973861157&doi=10.5194%2facp-16-6841-2016&partnerID=40&md5=7ed434b58fdb512d40cc2e6ad758798f","In this paper we combine SO2 and ash plume dispersion modelling with satellite and surface remote sensing observations to study the regional influence of a relatively weak volcanic eruption from Mount Etna on the optical and micro-physical properties of Mediterranean aerosols. We analyse the Mount Etna eruption episode of 25-27 October 2013. The evolution of the plume along the trajectory is investigated by means of the FLEXible PARTicle Lagrangian dispersion (FLEXPART) model. The satellite data set includes true colour images, retrieved values of volcanic SO2 and ash, estimates of SO2 and ash emission rates derived from MODIS (MODerate resolution Imaging Spectroradiometer) observations and estimates of cloud top pressure from SEVIRI (Spinning Enhanced Visible and InfraRed Imager). Surface remote sensing measurements of aerosol and SO2 made at the ENEA Station for Climate Observations (35.52° N, 12.63° E; 50 m a.s.l.) on the island of Lampedusa are used in the analysis. The combination of these different data sets suggests that SO2 and ash, despite the initial injection at about 7.0 km altitude, reached altitudes around 10-12 km and influenced the column average aerosol particle size distribution at a distance of more than 350 km downwind. This study indicates that even a relatively weak volcanic eruption may produce an observable effect on the aerosol properties at the regional scale. The impact of secondary sulfate particles on the aerosol size distribution at Lampedusa is discussed and estimates of the clear-sky direct aerosol radiative forcing are derived. Daily shortwave radiative forcing efficiencies, i.e. radiative forcing per unit AOD (aerosol optical depth), are calculated with the LibRadtran model. They are estimated between -39 and -48 W m-2 AOD-1 at the top of the atmosphere and between -66 and -49 W m-2 AOD-1 at the surface, with the variability in the estimates mainly depending on the aerosol single scattering albedo. These results suggest that sulfate particles played a large role in the transported plume composition and radiative forcing, while the contribution by ash particles was small in the volcanic plume arriving at Lampedusa during this event."
"56364931100;8728433200;24722810700;57202142004;8883143500;57203231853;7501381728;36172075700;8608660400;7004027519;","Dimethyl sulfide in the summertime Arctic atmosphere: Measurements and source sensitivity simulations",2016,"10.5194/acp-16-6665-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973520055&doi=10.5194%2facp-16-6665-2016&partnerID=40&md5=4be2b75b37fd389835a4b0d418db66da","Dimethyl sulfide (DMS) plays a major role in the global sulfur cycle. In addition, its atmospheric oxidation products contribute to the formation and growth of atmospheric aerosol particles, thereby influencing cloud condensation nuclei (CCN) populations and thus cloud formation. The pristine summertime Arctic atmosphere is strongly influenced by DMS. However, atmospheric DMS mixing ratios have only rarely been measured in the summertime Arctic. During July-August, 2014, we conducted the first high time resolution (10 Hz) DMS mixing ratio measurements for the eastern Canadian Archipelago and Baffin Bay as one component of the Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments (NETCARE). DMS mixing ratios ranged from below the detection limit of 4 to 1155 pptv (median 186 pptv) during the 21-day shipboard campaign. A transfer velocity parameterization from the literature coupled with coincident atmospheric and seawater DMS measurements yielded air-sea DMS flux estimates ranging from 0.02 to 12 μmolm-2 d-1. Air-mass trajectory analysis using FLEXPART-WRF and sensitivity simulations with the GEOS-Chem chemical transport model indicated that local sources (Lancaster Sound and Baffin Bay) were the dominant contributors to the DMS measured along the 21-day ship track, with episodic transport from the Hudson Bay System. After adjusting GEOS-Chem oceanic DMS values in the region to match measurements, GEOS-Chem reproduced the major features of the measured time series but was biased low overall (2-1006 pptv, median 72 pptv), although within the range of uncertainty of the seawater DMS source. However, during some 1-2 day periods the model underpredicted the measurements by more than an order of magnitude. Sensitivity tests indicated that non-marine sources (lakes, biomass burning, melt ponds, and coastal tundra) could make additional episodic contributions to atmospheric DMS in the study region, although local marine sources of DMS dominated. Our results highlight the need for both atmospheric and seawater DMS data sets with greater spatial and temporal resolution, combined with further investigation of non-marine DMS sources for the Arctic. © 2016 Author(s)."
"13402835300;26659013400;24168416900;7404142321;7103016965;26659116700;6603153821;56493740900;","Large contribution of supercooled liquid clouds to the solar radiation budget of the Southern Ocean",2016,"10.1175/JCLI-D-15-0564.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971467699&doi=10.1175%2fJCLI-D-15-0564.1&partnerID=40&md5=ea3ebb5aa03a1e76d083d346f194079f","The Southern Ocean is a critical region for global climate, yet large cloud and solar radiation biases over the Southern Ocean are a long-standing problem in climate models and are poorly understood, leading to biases in simulated sea surface temperatures. This study shows that supercooled liquid clouds are central to understanding and simulating the Southern Ocean environment. A combination of satellite observational data and detailed radiative transfer calculations is used to quantify the impact of cloud phase and cloud vertical structure on the reflected solar radiation in the Southern Hemisphere summer. It is found that clouds with supercooled liquid tops dominate the population of liquid clouds. The observations show that clouds with supercooled liquid tops contribute between 27% and 38% to the total reflected solar radiation between 40° and 70°S, and climate models are found to poorly simulate these clouds. The results quantify the importance of supercooled liquid clouds in the Southern Ocean environment and highlight the need to improve understanding of the physical processes that control these clouds in order to improve their simulation in numerical models. This is not only important for improving the simulation of present-day climate and climate variability, but also relevant for increasing confidence in climate feedback processes and future climate projections. © 2016 American Meteorological Society."
"56457851700;55683910600;7202145115;26645289600;13403622000;","On the relationships among cloud cover, mixed-phase partitioning, and planetary albedo in GCMs",2016,"10.1002/2015MS000589","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966415563&doi=10.1002%2f2015MS000589&partnerID=40&md5=867f80a552bfb838b43f52b07a88a0dc","In this study, it is shown that CMIP5 global climate models (GCMs) that convert supercooled water to ice at relatively warm temperatures tend to have a greater mean-state cloud fraction and more negative cloud feedback in the middle and high latitude Southern Hemisphere. We investigate possible reasons for these relationships by analyzing the mixed-phase parameterizations in 26 GCMs. The atmospheric temperature where ice and liquid are equally prevalent (T5050) is used to characterize the mixed-phase parameterization in each GCM. Liquid clouds have a higher albedo than ice clouds, so, all else being equal, models with more supercooled liquid water would also have a higher planetary albedo. The lower cloud fraction in these models compensates the higher cloud reflectivity and results in clouds that reflect shortwave radiation (SW) in reasonable agreement with observations, but gives clouds that are too bright and too few. The temperature at which supercooled liquid can remain unfrozen is strongly anti-correlated with cloud fraction in the climate mean state across the model ensemble, but we know of no robust physical mechanism to explain this behavior, especially because this anti-correlation extends through the subtropics. A set of perturbed physics simulations with the Community Atmospheric Model Version 4 (CAM4) shows that, if its temperature-dependent phase partitioning is varied and the critical relative humidity for cloud formation in each model run is also tuned to bring reflected SW into agreement with observations, then cloud fraction increases and liquid water path (LWP) decreases with T5050, as in the CMIP5 ensemble. © 2016. The Authors."
"57196447025;16402988900;56984682300;13611521400;7404815507;8439519800;57190167593;56953933900;","Operational climate prediction in the era of big data in China: Reviews and prospects",2016,"10.1007/s13351-016-6081-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978161961&doi=10.1007%2fs13351-016-6081-3&partnerID=40&md5=262efafce1a20bca3dcb261d95710268","Big data has emerged as the next technological revolution in IT industry after cloud computing and the Internet of Things. With the development of climate observing systems, particularly satellite meteorological observation and high-resolution climate models, and the rapid growth in the volume of climate data, climate prediction is now entering the era of big data. The application of big data will provide new ideas and methods for the continuous development of climate prediction. The rapid integration, cloud storage, cloud computing, and full-sample analysis of massive climate data makes it possible to understand climate states and their evolution more objectively, thus predicting the future climate more accurately. This paper describes the application status of big data in operational climate prediction in China; it analyzes the key big data technologies, discusses the future development of climate prediction operations from the perspective of big data, speculates on the prospects for applying climatic big data in cloud computing and data assimilation, and puts forward the notion of big data-based super-ensemble climate prediction methods and computerbased deep learning climate prediction methods. © 2016, The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg."
"57203030873;57033686900;56297151300;8866821900;36876405100;36856321600;6602558284;","No access global climate impacts of fixing the Southern Ocean shortwave radiation bias in the Community Earth System Model (CESM)",2016,"10.1175/JCLI-D-15-0358.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971457292&doi=10.1175%2fJCLI-D-15-0358.1&partnerID=40&md5=690e7d1049b01d69b003e9f07f90e0c2","A large, long-standing, and pervasive climate model bias is excessive absorbed shortwave radiation (ASR) over the midlatitude oceans, especially the Southern Ocean. This study investigates both the underlying mechanisms for and climate impacts of this bias within the Community Earth System Model, version 1, with the Community Atmosphere Model, version 5 [CESM1(CAM5)]. Excessive Southern Ocean ASR in CESM1(CAM5) results in part because low-level clouds contain insufficient amounts of supercooled liquid. In a present-day atmosphere-only run, an observationally motivated modification to the shallow convection detrainment increases supercooled cloud liquid, brightens low-level clouds, and substantially reduces the Southern Ocean ASR bias. Tuning to maintain global energy balance enables reduction of a compensating tropical ASR bias. In the resulting preindustrial fully coupled run with a brighter Southern Ocean and dimmer tropics, the Southern Ocean cools and the tropics warm. As a result of the enhanced meridional temperature gradient, poleward heat transport increases in both hemispheres (especially the Southern Hemisphere), and the Southern Hemisphere atmospheric jet strengthens. Because northward cross-equatorial heat transport reductions occur primarily in the ocean (80%), not the atmosphere (20%), a proposed atmospheric teleconnection linking Southern Ocean ASR bias reduction and cooling with northward shifts in tropical precipitation has little impact. In summary, observationally motivated supercooled liquid water increases in shallow convective clouds enable large reductions in long-standing climate model shortwave radiation biases. Of relevance to both model bias reduction and climate dynamics, quantifying the influence of Southern Ocean cooling on tropical precipitation requires a model with dynamic ocean heat transport. © 2016 American Meteorological Society."
"56567409000;23492864500;7201504886;","The role of precipitation and spatial organization in the response of trade-wind clouds to warming",2016,"10.1002/2015MS000568","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973596894&doi=10.1002%2f2015MS000568&partnerID=40&md5=303428d89742eb71514ba2b52edd4300","Using highly resolved large-eddy simulations on two different domain sizes, we investigate the influence of precipitation and spatial organization on the thermodynamic structure of the trade-wind layer, under a uniform 4 K warming at constant relative humidity. In nonprecipitating simulations, the increased surface latent heat flux in the warmer climate produces a deeper and drier cloud layer with reduced cloud fractions between 1.5 and 4 km. Precipitation prevents the deepening and drying of the cloud layer in response to warming. Cloud fractions still decrease in the upper cloud layer, because stratiform outflow layers near cloud tops are less pronounced and because the larger liquid water contents are confined to narrower updrafts. Simulations on a 16-fold larger domain lead to the spatial organization of clouds into larger and deeper cloud clusters. The presence of deeper clouds results in a shallower, warmer, and drier trade-wind layer, with strongly reduced cloud cover. The warming response in the precipitating large-domain simulation nevertheless remains similar to the small-domain precipitating simulation. On the large domain, deeper clouds can also develop without precipitation, because moisture-convection feedbacks strengthen in the absence of cold-pool dynamics. Overall, total cloud cover and albedo decrease only slightly with warming in all cases. This demonstrates the robustness of shallow cumuli—in particular of cloud fraction near the lifting condensation level—to changes in the large-scale environment. © 2016. The Authors."
"25941200000;8397494800;7410070663;6603613067;","A parametrization of 3-D subgrid-scale clouds for conventional GCMs: Assessment using A-Train satellite data and solar radiative transfer characteristics",2016,"10.1002/2015MS000601","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979725527&doi=10.1002%2f2015MS000601&partnerID=40&md5=5b6f0967395c4945565c0783b955c5be","A stochastic algorithm for generating 3-D cloud fields based on profiles of cloud fraction (Formula presented.) and mean cloud water content is presented and assessed using cloud properties inferred from A-Train satellite data. The ultimate intention is to employ the algorithm, along with 3-D radiative transfer (RT) models, in Global Climate Models (GCMs). The algorithm approaches cloud fields as whole objects demarcated by contiguous layers with (Formula presented.). This contrasts with conventional GCM radiation routines that deal with clouds on a per-(arbitrary) layer basis. A-Train cloud data for August 2007 were partitioned into ∼29,000 domains, each ∼280 km long, to represent nominal GCM columns. For each A-Train/stochastic pair of domains, profiles of domain-averaged fluxes were computed by a 1-D broadband solar RT model in Independent Column Approximation mode. Globally averaged, mean bias error for upwelling radiation at top-of-atmosphere (TOA) is 6.8 W m−2. Upon advancing the RT model to 2-D, differences between 1-D and 2-D upwelling fluxes at TOA for A-Train domains differed from corresponding differences for model-generated domains by ∼1 W m−2, on average, with differences for the model domains exhibiting stronger dependence on solar zenith angle (Formula presented.). Moving on to 3-D RT for model domains, 1-D–3-D differences became slightly stronger functions of (Formula presented.) thanks mostly to accentuated 3-D effects at small (Formula presented.). Simple parametrizations for the stochastic algorithm's variables that govern horizontal and vertical structure of clouds should be adequate to capture the ramifications of systematic neglect of 3-D solar RT in GCMs. © 2016. The Authors and Her Majesty the Queen in Right of Canada. Reproduced with the permission of the Minister of the Environment."
"55373004600;57208346904;","Effects of cumulus parameterization closures on simulations of summer precipitation over the United States coastal oceans",2016,"10.1002/2015MS000621","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979520538&doi=10.1002%2f2015MS000621&partnerID=40&md5=976ea6d0342df076651e6851a377d0a3","This study evaluates the effects of major cumulus parameterization closures on summer precipitation simulations over the U.S. Atlantic Coasts and Gulf of Mexico. A series of mesoscale regional climate model simulations using an Ensemble Cumulus Parameterization (ECP) that incorporates multiple alternate closure schemes into a single cloud model formulation are conducted and compared to determine the systematic errors and relative performances of individual and combined closures in capturing precipitation spatiotemporal variations. The results show that closure algorithms largely affect precipitation's geographic distribution, frequency and intensity, and diurnal cycle. The quasi-equilibrium and total instability adjustment closures simulate widespread wet biases, while the instability tendency closure produces systematic dry biases. Two closure algorithms based on the average vertical velocity at the cloud base and column moisture convergence complementarily reproduce the observed precipitation pattern and amount, and capture the frequency of heavy rainfall events better than other closures. In contrast, the instability tendency closures are better at capturing the diurnal phase but yield much larger deficits in amount. Therefore, cloud base vertical velocity and moisture convergence may be the primary factors controlling precipitation seasonal mean and daily variation, while the instability tendency may play a critical role in regulating the diurnal cycle phase. © 2016. The Authors."
"55822925800;55713442200;7406671641;22236221300;7006199823;6701752471;55286185400;","The role of large-scale feedbacks in cumulus convection parameter estimation",2016,"10.1175/JCLI-D-15-0117.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971467985&doi=10.1175%2fJCLI-D-15-0117.1&partnerID=40&md5=fb849aab4a4a514e60e6f9724c5c3a51","Uncertainty in cumulus convection parameterization is one of the most important causes of model climate drift through interactions between large-scale background and local convection that use empirically set parameters. Without addressing the large-scale feedback, the calibrated parameter values within a convection scheme are usually not optimal for a climate model. This study first designs a multiple-column atmospheric model that includes large-scale feedbacks for cumulus convection and then explores the role of large-scale feedbacks in cumulus convection parameter estimation using an ensemble filter. The performance of convection parameter estimation with or without the presence of large-scale feedback is examined. It is found that including large-scale feedbacks in cumulus convection parameter estimation can significantly improve the estimation quality. This is because large-scale feedbacks help transform local convection uncertainties into global climate sensitivities, and including these feedbacks enhances the statistical representation of the relationship between parameters and state variables. The results of this study provide insights for further understanding of climate drift induced from imperfect cumulus convection parameterization, which may help improve climate modeling. © 2016 American Meteorological Society."
"57189000835;57015826100;55519994900;7103158465;56162305900;23991212200;","Sensitivity of summer ensembles of fledgling superparameterized U.S. mesoscale convective systems to cloud resolving model microphysics and grid configuration",2016,"10.1002/2015MS000567","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992305862&doi=10.1002%2f2015MS000567&partnerID=40&md5=4b0648d0e399d45424aa3eb97973d96a","The sensitivities of simulated mesoscale convective systems (MCSs) in the central U.S. to microphysics and grid configuration are evaluated here in a global climate model (GCM) that also permits global-scale feedbacks and variability. Since conventional GCMs do not simulate MCSs, studying their sensitivities in a global framework useful for climate change simulations has not previously been possible. To date, MCS sensitivity experiments have relied on controlled cloud resolving model (CRM) studies with limited domains, which avoid internal variability and neglect feedbacks between local convection and larger-scale dynamics. However, recent work with superparameterized (SP) GCMs has shown that eastward propagating MCS-like events are captured when embedded CRMs replace convective parameterizations. This study uses a SP version of the Community Atmosphere Model version 5 (SP-CAM5) to evaluate MCS sensitivities, applying an objective empirical orthogonal function algorithm to identify MCS-like events, and harmonizing composite storms to account for seasonal and spatial heterogeneity. A five-summer control simulation is used to assess the magnitude of internal and interannual variability relative to 10 sensitivity experiments with varied CRM parameters, including ice fall speed, one-moment and two-moment microphysics, and grid spacing. MCS sensitivities were found to be subtle with respect to internal variability, and indicate that ensembles of over 100 storms may be necessary to detect robust differences in SP-GCMs. These results emphasize that the properties of MCSs can vary widely across individual events, and improving their representation in global simulations with significant internal variability may require comparison to long (multidecadal) time series of observed events rather than single season field campaigns. © 2016. The Authors."
"7004764167;24329376600;36842027200;35742922300;16177522400;55318394800;6603153821;37019252000;36106706200;7006766881;7003976079;7007021059;","Idealized climate change simulations with a high-resolution physical model: HadGEM3-GC2",2016,"10.1002/2015MS000614","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971432659&doi=10.1002%2f2015MS000614&partnerID=40&md5=9df517c0257d72bcb976eb2292a66874","Idealized climate change simulations with a new physical climate model, HadGEM3-GC2 from The Met Office Hadley Centre are presented and contrasted with the earlier MOHC model, HadGEM2-ES. The role of atmospheric resolution is also investigated. The Transient Climate Response (TCR) is 1.9 K/2.1 K at N216/N96 and Effective Climate Sensitivity (ECS) is 3.1 K/3.2 K at N216/N96. These are substantially lower than HadGEM2-ES (TCR: 2.5 K; ECS: 4.6 K) arising from a combination of changes in the size of climate feedbacks. While the change in the net cloud feedback between HadGEM3 and HadGEM2 is relatively small, there is a change in sign of its longwave and a strengthening of its shortwave components. At a global scale, there is little impact of the increase in atmospheric resolution on the future climate change signal and even at a broad regional scale, many features are robust including tropical rainfall changes, however, there are some significant exceptions. For the North Atlantic and western Europe, the tripolar pattern of winter storm changes found in most CMIP5 models is little impacted by resolution but for the most intense storms, there is a larger percentage increase in number at higher resolution than at lower resolution. Arctic sea-ice sensitivity shows a larger dependence on resolution than on atmospheric physics. © 2016. The Authors."
"7201398636;7005868133;7005872245;","Pathways to the production of precipitating hydrometeors and tropical cyclone development",2016,"10.1175/MWR-D-15-0363.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84974784172&doi=10.1175%2fMWR-D-15-0363.1&partnerID=40&md5=9659811bea4dc134c0f9525a2ea0fe4d","Pathways to the production of precipitation in two cloud microphysics schemes available in the Weather Research and Forecasting (WRF) Model are investigated in a scenario of tropical cyclone intensification. Comparisons of the results from the WRF Model simulations indicate that the variation in the simulated initial rapid intensification of an idealized tropical cyclone is due to the differences between the two cloud microphysics schemes in their representations of pathways to the formation and growth of precipitating hydrometeors. Diagnoses of the source and sink terms of the hydrometeor budget equations indicate that the major differences in the production of hydrometeors between the schemes are in the spectral definition of individual hydrometeor categories and spectrum-dependent microphysical processes, such as accretion growth and sedimentation. These differences lead to different horizontally averaged vertical profiles of net latent heating rate associated with significantly different horizontally averaged vertical distributions and production rates of hydrometeors in the simulated clouds. Results from this study also highlight the possibility that the advantage of double-moment formulations can be overshadowed by the uncertainties in the spectral definition of individual hydrometeor categories and spectrum-dependent microphysical processes. © 2016 American Meteorological Society."
"52564166000;6602729528;6603584184;7005626683;8571302000;6602699701;","Influence of synoptic weather patterns on solar irradiance variability in northern Europe",2016,"10.1175/JCLI-D-15-0476.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971426740&doi=10.1175%2fJCLI-D-15-0476.1&partnerID=40&md5=25c552e60945784372960480c4491111","Observations have revealed strong variability of shortwave (SW) irradiance at Earth's surface on decadal time scales, referred to as global dimming and brightening. Previous studies have attributed the dimming and brightening to changes in clouds and atmospheric aerosols. This study assesses the influence of atmospheric circulation on clouds and SW irradiance to separate the influence of ""natural"" SW variability from direct and, to some extent, indirect aerosol effects. The focus is on SW irradiance in northern Europe in summer and spring because there is little high-latitude SW irradiance during winter. As a measure of large-scale circulation the Grosswetterlagen (GWL) dataset, a daily classification of synoptic weather patterns, is used. Empirical models of normalized SW irradiance are constructed based on the GWL, relating the synoptic weather patterns to the local radiative climate. In summer, a temporary SW peak in the 1970s and subsequent dimming is linked to variations in the synoptic patterns over Scandinavia, possibly related to a northward shift in the North Atlantic storm track. In spring, a decrease of anticyclonic and increase of cyclonic weather patterns over northern Europe contributes to the dimming from the 1960s to 1990. At many sites, there is also a residual SW irradiance trend not explained by the GWL model: a weak nonsignificant residual dimming from the 1950s or 1960s to around 1990, followed by a statistically significant residual brightening. It is concluded that factors other than the large-scale circulation (e.g., decreasing aerosol emissions) also play an important role in northern Europe. © 2016 American Meteorological Society."
"36017879100;56734847200;36499103100;56294871100;","Can the Tibetan Plateau snow cover influence the interannual variations of Eurasian heat wave frequency?",2016,"10.1007/s00382-015-2775-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84937825137&doi=10.1007%2fs00382-015-2775-y&partnerID=40&md5=4eeb3329bbbfcbd449deb1822a536479","The Eurasian continent has experienced significant year-to-year variations of summer heat waves during the past decades. Several possible factors, such as ocean temperature, soil moisture, and changes in land use and greenhouse gases, have been identified in previous studies, but the mechanisms are still unclear. In this study, it is found that the Tibetan Plateau snow cover (TPSC) is closely linked to the interannual variations of summer heat waves over Eurasia. The TPSC variability explains more than 30 % of the total variances of heat wave variability in the southern Europe and northeastern Asia (SENA) region. A set of numerical experiments reveal that the reduced TPSC may induce a distinct teleconnection pattern across the Eurasian continent, with two anomalous high pressure centers in the upper troposphere over the SENA region, which may lead to a reduction of the cloud formation near the surface. The less cloud cover tends to increase the net shortwave radiation and favor a stronger surface sensible heat flux in the dry surface condition over the SENA region, resulting in a deeper, warmer and drier atmospheric boundary layer that would further inhibit the local cloud formation. Such a positive land–atmosphere feedback may dry the surface even further, heat the near-surface atmosphere and thereby intensify the local heat waves. The above dynamical processes also operate on interdecadal time scales. Given the reduction of the TPSC could become more pronounced with increasing levels of greenhouse gases in a warming climate, we infer that the TPSC may play an increasingly important role in shaping the summer heat waves over the SENA region in next decades. © 2015, Springer-Verlag Berlin Heidelberg."
"18438817800;21735084500;35168107300;7003614389;6603657014;","Climatic and societal impacts of a volcanic double event at the dawn of the Middle Ages",2016,"10.1007/s10584-016-1648-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963642337&doi=10.1007%2fs10584-016-1648-7&partnerID=40&md5=e9e9f63a627f12311949620ca1d6e190","Volcanic activity in and around the year 536 CE led to severe cold and famine, and has been speculatively linked to large-scale societal crises around the globe. Using a coupled aerosol-climate model, with eruption parameters constrained by recently re-dated ice core records and historical observations of the aerosol cloud, we reconstruct the radiative forcing resulting from a sequence of two major volcanic eruptions in 536 and 540 CE. We estimate that the decadal-scale Northern Hemisphere (NH) extra-tropical radiative forcing from this volcanic “double event” was larger than that of any period in existing reconstructions of the last 1200 years. Earth system model simulations including the volcanic forcing show peak NH mean temperature anomalies reaching more than −2 °C, and show agreement with the limited number of available maximum latewood density temperature reconstructions. The simulations also produce decadal-scale anomalies of Arctic sea ice. The simulated cooling is interpreted in terms of probable impacts on agricultural production in Europe, and implies a high likelihood of multiple years of significant decreases in crop production across Scandinavia, supporting the theory of a connection between the 536 and 540 eruptions and evidence of societal crisis dated to the mid-6th century. © 2016, The Author(s)."
"57197183027;7003785403;","Scottish snow cover dependence on the North Atlantic Oscillation index",2016,"10.2166/nh.2016.085","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975740653&doi=10.2166%2fnh.2016.085&partnerID=40&md5=c2c0f7485d56676c9662216aaa35aebb","Forecasting seasonal snow cover is useful for planning resources and mitigating natural hazards. We present a link between the North Atlantic Oscillation (NAO) index and days of snow cover in Scotland between winters beginning from 1875 to 2013. Using broad (5 km resolution), national scale data sets like UK Climate Projections 2009 (UKCP09) to extract nationwide patterns, we support these findings using hillslope scale data from the Snow Survey of Great Britain (SSGB). Currently collected snow cover data are considered using remotely sensed satellite observations, from moderateresolution imaging spectroradiometer; but the results are inconclusive due to cloud. The strongest correlations between the NAO index and snow cover are found in eastern and southern Scotland; these results are supported by both SSGB and UKCP09 data. Correlations between NAO index and snow cover are negative with the strongest relationships found for elevations below 750 m. Four SSGB sites (two in eastern Scotland, two in southern Scotland) were modelled linearly with resulting slopes between -6 and -16 days of snow cover per NAO index integer value. This is the first time the relationship between NAO index and snow cover duration has been quantified and mapped in Scotland. Keywords | climate, North Atlantic Oscillation, Scotland, snow. © 2016 The Authors."
"45961133700;7401929481;55954376100;57189631893;57203012951;7404768480;","Compiling a new glacier inventory for southeastern Qinghai-Tibet Plateau from Landsat and Palsar data",2016,"10.1017/jog.2016.58","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979700550&doi=10.1017%2fjog.2016.58&partnerID=40&md5=53e6d966b5ce1ceef0845b1e8f07db0e","Glacier change has been recognized as an important climate variable due to its sensitive response to climate change. Although there are a large number of glaciers distributed over the southeastern Qinghai-Tibetan Plateau, the region is poorly represented in glacier databases due to seasonal snow cover and frequent cloud cover. Here, we present an improved glacier inventory for this region by combining Landsat observations acquired over 2011-13 (Landsat 8/OLI and Landsat TM/ETM+), coherence images from Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar images and the Shuttle Radar Topography Mission (SRTM) DEM. We present a semi-automated scheme for integrating observations from multi-temporal Landsat scenes to mitigate cloud obscuration. Further, the clean-ice observations, together with coherence information, slope constraints, vegetation cover and water classification information extracted from the Landsat scenes, are integrated to determine the debris-covered glacier area. After manual editing, we derive a new glacier inventory containing 6892 glaciers &gt;0.02 km2, covering a total area of 6566 ± 197 km2. This new glacier inventory indicates gross overestimation in glacier area (over 30%) in previously published glacier inventories, and reveals various spatial characteristics of glaciers in the region. Our inventory can be used as a baseline dataset for future studies including glacier change assessment. © The Author(s) 2016."
"55933133600;7004861251;","Evaluation of extreme rainfall and temperature over North America in CanRCM4 and CRCM5",2016,"10.1007/s00382-015-2807-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949560963&doi=10.1007%2fs00382-015-2807-7&partnerID=40&md5=c54fc7116b7af36e6d5dc310b2f2bcc0","We assess the ability of two Canadian regional climate models (RCMs), CanRCM4 and CRCM5, to simulate North American climate extremes over the period 1989–2009. Both RCMs use lateral boundary conditions derived from the ERA-Interim reanalysis and share the same dynamical core but use different nesting strategies, land-surface and physics schemes. The annual cycle and spatial patterns of extreme temperature indices are generally well reproduced in both models but the magnitude varies. In central and southern North America, maximum temperature extremes are up to 7 °C warmer in CanRCM4. There is a cool bias in minimum temperature extremes in both RCMs. The shape of the annual cycle of extreme rainfall varies between simulations. There is a wet bias in CRCM5 extreme rainfall on the west coast throughout the year and in winter rainfall elsewhere. In summer both RCMs have precipitation biases in the south-east. These rainfall and temperature biases are likely associated with differences in the physical parameterisation of rainfall. CanRCM4 simulates too little convective rainfall, while over-estimating large-scale rainfall; nevertheless, cloud cover is well simulated. CRCM5 simulates more large-scale rainfall throughout the year on the west coast and in winter in other regions. The spatial extent, intensity and location of atmospheric river (AR) landfall are well reproduced by the RCMs, as is the fraction of winter rainfall from AR days. Spectral nudging improves agreement on landfall latitude between the RCM and the driving model without greatly diminishing the intensity of the rainfall extreme. © 2015, The Author(s)."
"56266792700;55703823500;","Nonlinear effect on the East Asian summer monsoon due to two coexisting anthropogenic forcing factors in eastern China: an AGCM study",2016,"10.1007/s00382-015-2803-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84940182661&doi=10.1007%2fs00382-015-2803-y&partnerID=40&md5=12ebce9a7298d1939b165cd240d38828","Two anthropogenic forcing factors dominate in eastern China: aerosols and urban land cover. Usually, aerosols induce surface cooling while urban land cover causes surface warming. It is important to explore whether or not a nonlinear effect may result from the coexistence of these two opposing effects, and to what extent such nonlinear effect may become significant in affecting the climate change in East Asia. In this study, the Community Atmosphere Model version 5.1 (CAM5.1) coupled with the Community Land Model version 4 (CLM4) is employed to investigate the nonlinear effect on the East Asian summer monsoon due to the coexistence of aerosols and urban land cover. The anthropogenic forcing can be studied by including only aerosol emissions, only urban land cover, or a combination of the two in eastern China. The nonlinear effect obtained in CAM5.1 is evident in eastern China to offset the urbanization effect. Large-scale atmospheric response produces anomalous upward motion and increases total cloud amount and precipitation. This increased total cloud amount and its associated negative shortwave cloud forcing in turn significantly decrease surface air temperature and cool the troposphere, especially in northern China, resulting in a reduced land–sea thermal contrast, which acts to weaken the prevailing southwesterly wind over the Yangtze River Valley and southwestern China and to enhance the wind over the northern South China Sea. The nonlinear effect also indirectly excites strong convection over southern China, leading to a pronounced increase in summer precipitation. © 2015, Springer-Verlag Berlin Heidelberg."
"7103274591;57189378755;","Predicting convective rainfall over tropical oceans from environmental conditions",2016,"10.1002/2015MS000595","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84970021348&doi=10.1002%2f2015MS000595&partnerID=40&md5=cc1c0ad1607cd84ad31cf6e06992a5e2","A cloud resolving model in spectral weak temperature gradient mode is used to explore systematically the response of mean convective rainfall to variations tropical environmental conditions. A very large fraction of the variance in modeled rainfall is explained by three variables, the surface moist entropy flux, the instability index (a measure of low to midlevel moist convective instability), and the saturation fraction (a kind of column-averaged relative humidity). The results of these calculations are compared with the inferred rainfall from 37 case studies of convection over the tropical west Pacific, the tropical Atlantic, and the Caribbean, as well as in the NCEP FNL analysis and the ERA-Interim reanalysis. The model shows significant predictive skill in all of these cases. However, it consistently overpredicts precipitation by about a factor of three, due possibly to simplifications made in the model. These calculations also show that the saturation fraction is not a predictor of rainfall in the case of strong convection. Instead, saturation fraction covaries with the precipitation as a result of a moisture quasi-equilibrium process. © 2016. The Authors."
"56471281900;56014511300;","No access practical approximations to seasonal fluctuation-dissipation operators given a limited sample",2016,"10.1175/JAS-D-15-0279.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976448188&doi=10.1175%2fJAS-D-15-0279.1&partnerID=40&md5=bb881f95d8bb3d55ea8275bdf7180818","This paper studies operators inspired by the fluctuation-dissipation theorem that consider the seasonality (nonstationarity) of the climate system under conditions of limited sample size relevant to application of the method to observational records. The approach is used to predict the steady-state response of an atmospheric general circulation model to localized temperature perturbations. A seasonal operator nominally requires a much larger data sample than a stationary operator; the authors study some strategies to overcome this. First, two methods for approximating the seasonality of the system are examined. Second, an alternative ""transpose approach"" to the standard dimension reduction is considered that is more efficient and accurate for small sample sizes and additionally enables the use of a kernel, which provides a convenient way to incorporate prior physical understanding into the operator. All operators show considerable skill in predicting seasonal responses for a variety of variables (temperature, winds, rainfall, and cloud cover) and better skill in predicting the annual-mean ones. A comparison of these predictions to ones done on the same system with temporally fixed boundary conditions shows unexpectedly that skill is, if anything, improved by the presence of a seasonal cycle. The authors suggest that the extra complexity due to a seasonal system is outweighed by the added information due to the seasonal forcing and the effect of seasonality in smoothing out prediction errors. © 2016 American Meteorological Society."
"7402955227;35277762300;23566639200;55994734800;57206174471;","Fog drip maintains dry season ecological function in a California coastal pine forest",2016,"10.1002/ecs2.1364","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977658627&doi=10.1002%2fecs2.1364&partnerID=40&md5=6c55217417972b4fbd812f30643719a0","Fog drip is recognized as an important source of water for many ecosystems that often harbor a disproportionate fraction of endemic species. Characterizing and quantifying the ecological importance of fog drip in these ecosystems requires a range of approaches. We report on a multi-faceted study of Bishop pine (Pinus muricata D. Don) along a coastal-inland transect on an island off Southern California. Hourly sampling included micrometeorology, sap flux, and soil moisture. Monthly measurements included changes in tree girth, plant water stress, and isotopic values of fogwater, rainwater, and xylem water. These data show that summertime fog drip clearly affected soil moisture and maintained aspects of tree function, including leaf water relations, sap flux dynamics, and growth rates. Although water from fog drip to the soil surface was occasionally taken up by pine trees, as quantified with isotopic measurements and a Bayesian mixing model, this utilization of fog drip was highly variable in space and time. The proportion of fogwater inferred to have been used is also much less than has been demonstrated in more mesic coastal forest ecosystems using isotopic methods. These results thus suggest high ecosystem sensitivity to even moderate amounts of fog drip, a finding with important implications as climate change differentially affects fog and rain patterns. © 2016 Fischer et al."
"8716952600;55946567900;16643471600;57189713427;","Experimental assimilation of the GPM core observatory DPR reflectivity profiles for Typhoon Halong (2014)",2016,"10.1175/MWR-D-15-0399.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84974782892&doi=10.1175%2fMWR-D-15-0399.1&partnerID=40&md5=1f196b804a383966e5b248088b059b89","Space-based precipitation radar data have been underused in data assimilation studies and operations despite their valuable information on vertically resolved hydrometeor profiles around the globe. The authors developed direct assimilation of reflectivities (Ze) from the Dual-Frequency Precipitation Radar (DPR) on board the Global Precipitation Measurement (GPM) Core Observatory to improve mesoscale predictions. Based on comparisons with Ze observations, this cloud resolving model mostly reproduced Ze but produced overestimations of Ze induced by excessive snow with large diameter particles. With an ensemble-based variational scheme and preprocessing steps to properly treat reflectivity observations including conservative quality control and superobbing procedures, the authors assimilated DPR Ze and/or rain-affected radiances of GPM Microwave Imager (GMI) for the case of Typhoon Halong in July 2014. With the vertically resolving capability of DPR, the authors effectively selected Ze observations most suited to data assimilation, for example, by removing Ze above the melting layer to avoid contamination due to model bias. While the GMI radiance had large impacts on various control variables, the DPR made a fine delicate analysis of the rain mixing ratio and updraft. This difference arose from the observation characteristics (coverage width and spatial resolution), sensitivities represented in the observation operators, and structures of the background error covariance. Because the DPR assimilation corrected excessive increases in rain and clouds due to the radiance assimilation, the combined use of DPRand GMI generated more accurate analysis and forecast than separate use of them with respect to the agreement of observations and tropical cyclone position errors. © 2016 American Meteorological Society."
"55938693300;57209908958;24726233100;55278022900;","Impact of anthropogenic aerosols on summer precipitation in the Beijing–Tianjin–Hebei urban agglomeration in China: Regional climate modeling using WRF-Chem",2016,"10.1007/s00376-015-5103-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962124705&doi=10.1007%2fs00376-015-5103-x&partnerID=40&md5=643f6510c8fb05953d776cd83fcb5fe2","The WRF model with chemistry (WRF-Chem) was employed to simulate the impacts of anthropogenic aerosols on summer precipitation over the Beijing–Tianjin–Hebei urban agglomeration in China. With the aid of a high-resolution gridded inventory of anthropogenic emissions of trace gases and aerosols, we conducted relatively long-term regional simulations, considering direct, semi-direct and indirect effects of the aerosols. Comparing the results of sensitivity experiments with and without emissions, it was found that anthropogenic aerosols tended to enhance summer precipitation over the metropolitan areas. Domain-averaged rainfall was increased throughout the day, except for the time around noon. Aerosols shifted the precipitation probability distribution from light or moderate to extreme rain. Further analysis showed that the anthropogenic aerosol radiative forcing had a cooling effect at the land surface, but a warming effect in the atmosphere. However, enhanced convective strength and updrafts accompanied by water vapor increases and cyclone-like wind shear anomalies were found in the urban areas. These responses may originate from cloud microphysical effects of aerosols on convection, which were identified as the primary cause for the summer rainfall enhancement. © 2016, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg."
"10046276900;36730825100;36626171700;36926416100;36835829900;14622582000;54899537500;57188684139;57188688944;57188687103;26538380300;7501383116;7004590620;7005140378;7004035832;","Plant leaf wax biomarkers capture gradients in hydrogen isotopes of precipitation from the Andes and Amazon",2016,"10.1016/j.gca.2016.03.018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962289678&doi=10.1016%2fj.gca.2016.03.018&partnerID=40&md5=95a0a3d8063dca498282a7b158b865a8","Plant leaf waxes have been found to record the hydrogen isotopic composition of precipitation and are thus used to reconstruct past climate. To assess how faithfully they record hydrological signals, we characterize leaf wax hydrogen isotopic compositions in forest canopy trees across a highly biodiverse, 3 km elevation range on the eastern flank of the Andes. We sampled the dominant tree species and assessed their relative abundance in the tree community. For each tree we collected xylem and leaf samples for analysis of plant water and plant leaf wax hydrogen isotopic compositions. In total, 176 individuals were sampled across 32 species and 5 forest plots that span the gradient. We find both xylem water and leaf wax δD values of individuals correlate (R2 = 0.8 and R2 = 0.3 respectively) with the isotopic composition of precipitation (with an elevation gradient of -21‰ km-1). Minimal leaf water enrichment means that leaf waxes are straightforward recorders of the isotopic composition of precipitation in wet climates. For these tropical forests we find the average fractionation between source water and leaf wax for C29 n-alkanes, -129 ± 2‰ (s.e.m., n = 136), to be indistinguishable from that of temperate moist forests. For C28 n-alkanoic acids the average fractionation is -121 ± 3‰ (s.e.m., n = 102). Sampling guided by community assembly within forest plots shows that integrated plant leaf wax hydrogen isotopic compositions faithfully record the gradient of isotopes in precipitation with elevation (R2 = 0.97 for n-alkanes and 0.60 for n-alkanoic acids). This calibration study supports the use of leaf waxes as recorders of the isotopic composition of precipitation in lowland tropical rainforest, tropical montane cloud forests and their sedimentary archives. © 2016 Elsevier Ltd."
"55729666100;57194637069;55683172300;57189368112;55067058700;6602639521;26640423300;6603846002;7007160874;7004462227;","Airborne soil organic particles generated by precipitation",2016,"10.1038/ngeo2705","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973373609&doi=10.1038%2fngeo2705&partnerID=40&md5=2bc9c378f9e85268374517623d1c27c5","Airborne organic particles play a critical role in Earth's climate, public health, air quality, and hydrological and carbon cycles. However, sources and formation mechanisms for semi-solid and solid organic particles are poorly understood and typically neglected in atmospheric models. Laboratory evidence suggests that fine particles can be formed from impaction of mineral surfaces by droplets. Here, we use chemical imaging of particles collected following rain events in the Southern Great Plains, Oklahoma, USA and after experimental irrigation to show that raindrop impaction of soils generates solid organic particles. We find that after rain events, sub-micrometre solid particles, with a chemical composition consistent with soil organic matter, contributed up to 60% of atmospheric particles. Our irrigation experiments indicate that intensive water impaction is sufficient to cause ejection of airborne soil organic particles from the soil surface. Chemical imaging and micro-spectroscopy analysis of particle physico-chemical properties suggest that these particles may have important impacts on cloud formation and efficiently absorb solar radiation. We suggest that raindrop-induced formation of solid organic particles from soils may be a widespread phenomenon in ecosystems such as agricultural systems and grasslands where soils are exposed to strong, episodic precipitation events. © 2016 Macmillan Publishers Limited."
"55803016100;15026371500;55544443300;56033405100;","The precipitation response to an idealized subtropical continent",2016,"10.1175/JCLI-D-15-0616.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84974829665&doi=10.1175%2fJCLI-D-15-0616.1&partnerID=40&md5=8458a5a036fd48810ffe624e6942771c","A subtropical continent is added to two aquaplanet atmospheric general circulation models (AGCMs) to better understand the influence of land on tropical circulation and precipitation. The first model, the gray-radiation moist (GRaM) AGCM, has simplified physics, while the second model, the GFDL Atmospheric Model version 2.1 (AM2.1), is a fully comprehensive AGCM. Both models have a continent that is 60° wide in longitude from 10° to 30°N, in an otherwise slab-ocean-covered world. The precipitation response varies with cloudy- and clear-sky feedbacks and depends on continental albedo. In GRaM simulations with a continent, precipitation in the Northern Hemisphere decreases mostly as a result of decreased evaporation. In AM2.1 simulations, precipitation also shifts southward via Hadley circulation changes due to increasing albedo, but the radiative impact of clouds and moisture creates a more complex response. Results are similar when a seasonal cycle of insolation is included in AM2.1 simulations. The impact of a large, bright subtropical continent is to shift precipitation to the opposite hemisphere. In these simulations, the hemisphere of greater tropical precipitation is better predicted by the hemisphere with greater atmospheric energy input, as has been shown in previous literature, rather than the hemisphere that has higher surface temperature. © 2016 American Meteorological Society."
"7202386372;56037439800;55017656900;7403959083;","Rapid mesoscale environmental changes accompanying genesis of an unusual Tornado",2016,"10.1175/WAF-D-15-0105.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032681900&doi=10.1175%2fWAF-D-15-0105.1&partnerID=40&md5=08d3d73f3b6705c8d21c8b9f8e16392e","This study documents a very rapid increase in convective instability, vertical wind shear, and mesoscale forcing for ascent leading to the formation of a highly unusual tornado as detected by a ground-based microwave radiometer and wind profiler, and in 1-km resolution mesoanalyses. Mesoscale forcing for the rapid development of severe convection began with the arrival of a strong upper-level jet streak with pronounced divergence in its left exit region and associated intensification of the low-level flow to the south of a pronounced warm front. The resultant increase in stretching deformation along the front occurred in association with warming immediately to its south as low-level clouds dissipated. This created a narrow ribbon of intense frontogenesis and a rapid increase in convective available potential energy (CAPE) within 75 min of tornadogenesis. The Windsor, Colorado, storm formed at the juncture of this warm frontogenesis zone and a developing dryline. Storm-relative helicity suddenly increased to large values during this pretornadic period as a midtropospheric layer of strong southeasterly winds descended to low levels. The following events also occurred simultaneously within this short period of time: a pronounced decrease in midtropospheric equivalent potential temperature θe accompanying the descending jet, an increase in low-level θe associated with the surface sensible heating, and elimination of the capping inversion and convective inhibition. The simultaneous nature of these rapid changes over such a short period of time, not fully captured in Storm Prediction Center mesoanalyses, was likely critical in generating this unusual tornadic event. © 2016 American Meteorological Society."
"55822193100;12646465800;57196612094;6603549082;36999865300;56957126200;","Analyzing the Vegetation Parameterization in the TU-Wien ASCAT Soil Moisture Retrieval",2016,"10.1109/TGRS.2016.2519842","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976207486&doi=10.1109%2fTGRS.2016.2519842&partnerID=40&md5=50f925e133c2c4ede01bcbb25c453cfb","In microwave remote sensing of the Earth's surface, the satellite signal holds information on both soil moisture and vegetation. This necessitates a correction for vegetation effects when retrieving soil moisture. This paper assesses the strengths and weaknesses of the existing vegetation correction as part of the Vienna University of Technology (TU-Wien) method for soil moisture retrieval from coarse-scale active microwave observations. In this method, vegetation is based on a multiyear climatology of backscatter variations related to phenology. To assess the plausibility of the correction method, we first convert the correction terms for retrievals from the Advanced Scatterometer (ASCAT) into estimates of vegetation optical depth τa using a water-cloud model. The spatial and temporal behaviors of the newly developed τa are compared with the optical depth retrieved from passive microwave observations with the land parameter retrieval model τp. Spatial patterns correspond well, although low values for τa are found over boreal forests. Temporal correlation between the two products is high (R = 0.5), although negative correlations are observed in drylands. This comparison shows that τa and thus the vegetation correction method are sensitive to vegetation dynamics. Effects of the vegetation correction on soil moisture retrievals are investigated by comparing retrieved soil moisture before and after applying the correction term to modeled soil moisture. The vegetation correction increases the quality of the soil moisture product. In areas of high interannual variability in vegetation dynamics, we observed a negative impact of the vegetation correction on the soil moisture, with a decrease in correlation up to 0.4. It emphasizes the need for a dynamic vegetation correction in areas with high interannual variability. © 2016 IEEE."
"23091173900;","Reconstructing daily evapotranspiration data from multi-annual water budget using insolation and precipitation presence",2016,"10.1007/s12665-016-5801-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975862612&doi=10.1007%2fs12665-016-5801-4&partnerID=40&md5=edce5e7bf6c42ea88531722d6e984b93","This paper presents a simple method for reconstructing daily catchment-wide evapotranspiration (ET) where only two kinds of daily data are available, i.e., catchment-wide precipitation and streamflow at the outlet. Here, multi-annual ET of a catchment obtained from water budget is decomposed into daily values considering two daily factors of insolation at the top of atmosphere (r factor) and precipitation presence (h factor). Precipitation presence is adopted as a surrogate of humidity which is related to two effects of (1) atmospheric transmittance of insolation and (2) moisture diffusion near surface. It is hypothesized that daily humidity condition is described with precipitation presence of the day, the previous day, and the following day. On the basis of this idea, eight possible scenarios are proposed for humidity condition. This paper reports h values analyzed from long-term data of observed pan evaporation and precipitation for five stations in Korea. h values show significant difference between eight scenarios, implying that the proposed scheme is effective in distinguishing various atmospheric conditions in a simple manner. There exists a varying degree of seasonal and spatial variability in h. Such variability is geo-physiographically explained through analysis of other meteorological data such as relative humidity, cloud cover, sunshine duration, surface solar radiation, and wind speed. The proposed methodology is applied for reconstructing daily ET of a real catchment in Korea. Calculated daily ET values well agree with observed pan evaporation data. The proposed method is also well compared with the Priestley–Taylor method, where the latter requires daily air temperature. The proposed method successfully captures sudden daily ET fluctuations in accordance with precipitation presence which is hardly captured by the Priestley–Taylor method. Further, the reconstructed data nicely follow the trend of LandFlux-EVAL dataset. © 2016, Springer-Verlag Berlin Heidelberg."
"57208121852;","Limitations of passive remote sensing to constrain global cloud condensation nuclei",2016,"10.5194/acp-16-6595-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973569070&doi=10.5194%2facp-16-6595-2016&partnerID=40&md5=5973d3f321a160b8e388f096f8710cd6","Aerosol-cloud interactions are considered a key uncertainty in our understanding of climate change (Boucher et al., 2013). Knowledge of the global abundance of cloud condensation nuclei (CCN) is fundamental to determine the strength of the anthropogenic climate perturbation. Direct measurements are limited and sample only a very small fraction of the globe so that remote sensing from satellites and ground-based instruments is widely used as a proxy for cloud condensation nuclei (Nakajima et al., 2001; Andreae, 2009; Clarke and Kapustin, 2010; Boucher et al., 2013). However, the underlying assumptions cannot be robustly tested with the small number of measurements available so that no reliable global estimate of cloud condensation nuclei exists. This study overcomes this limitation using a self-consistent global model (ECHAM-HAM) of aerosol radiative properties and cloud condensation nuclei. An analysis of the correlation of simulated aerosol radiative properties and cloud condensation nuclei reveals that common assumptions about their relationships are violated for a significant fraction of the globe: 71% of the area of the globe shows correlation coefficients between CCN0.2% at cloud base and aerosol optical depth (AOD) below 0.5, i.e. AOD variability explains only 25% of the CCN variance. This has significant implications for satellite based studies of aerosol-cloud interactions. The findings also suggest that vertically resolved remote-sensing techniques, such as satellite-based high spectral resolution lidars, have a large potential for global monitoring of cloud condensation nuclei. © 2016 Author(s)."
"55966909500;7003740015;7006401274;","Size-resolved morphological properties of the high Arctic summer aerosol during ASCOS-2008",2016,"10.5194/acp-16-6577-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973550014&doi=10.5194%2facp-16-6577-2016&partnerID=40&md5=7b59428760f15d4957875de99dbdb822","The representation of aerosol properties and processes in climate models is fraught with large uncertainties. Especially at high northern latitudes a strong underprediction of aerosol concentrations and nucleation events is observed and can only be constrained by in situ observations based on the analysis of individual aerosol particles. To further reduce the uncertainties surrounding aerosol properties and their potential role as cloud condensation nuclei this study provides observational data resolved over size on morphological and chemical properties of aerosol particles collected in the summer high Arctic, north of 80° N. Aerosol particles were imaged with scanning and transmission electron microscopy and further evaluated with digital image analysis. In total, 3909 aerosol particles were imaged and categorized according to morphological similarities into three gross morphological groups: single particles, gel particles, and halo particles. Single particles were observed between 15 and 800 nm in diameter and represent the dominating type of particles (82 %). The majority of particles appeared to be marine gels with a broad Aitken mode peaking at 70 nm and accompanied by a minor fraction of ammonium (bi)sulfate with a maximum at 170 nm in number concentration. Gel particles (11% of all particles) were observed between 45 and 800 nm with a maximum at 154 nm in diameter. Imaging with transmission electron microscopy allowed further morphological discrimination of gel particles in ""aggregate"" particles, ""aggregate with film"" particles, and ""mucus-like"" particles. Halo particles were observed above 75 nm and appeared to be ammonium (bi)sulfate (59% of halo particles), gel matter (19 %), or decomposed gel matter (22 %), which were internally mixed with sulfuric acid, methane sulfonic acid, or ammonium (bi)sulfate with a maximum at 161 nm in diameter. Elemental dispersive X-ray spectroscopy analysis of individual particles revealed a prevalence of the monovalent ions Na+/K+ for single particles and aggregate particles and of the divalent ions Ca2+/Mg2+ for aggregate with film particles and mucus-like particles. According to these results and other model studies, we propose a relationship between the availability of Na+/K+ and Ca2+/Mg2+ and the length of the biopolymer molecules participating in the formation of the three-dimensional gel networks. © 2016 Author(s)."
"7003800456;56112266400;8263760800;57190047135;57190048278;35338710200;","Stratospheric aerosols from major volcanic eruptions: A composition-climate model study of the aerosol cloud dispersal and e-folding time",2016,"10.3390/atmos7060075","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976884421&doi=10.3390%2fatmos7060075&partnerID=40&md5=6545e48743f6fdb94dbfac2f0155bdf6","Large explosive volcanic eruptions are capable of injecting considerable amounts of particles and sulfur gases above the tropopause, causing large increases in stratospheric aerosols. Five major volcanic eruptions after 1960 (i.e.; Agung, St. Helens, El Chichón, Nevado del Ruiz and Pinatubo) have been considered in a numerical study conducted with a composition-climate coupled model including an aerosol microphysics code for aerosol formation and growth. Model results are compared between an ensemble of numerical simulations including volcanic aerosols and their radiative effects (VE) and a reference simulations ensemble (REF) with no radiative impact of the volcanic aerosols. Differences of VE-REF show enhanced diabatic heating rates; increased stratospheric temperatures and mean zonal westerly winds; increased planetary wave amplitude; and tropical upwelling. The impact on stratospheric upwelling is found to be larger when the volcanically perturbed stratospheric aerosol is confined to the tropics, as tends to be the case for eruptions which were followed by several months with easterly shear of the quasi-biennial oscillation (QBO), e.g.; the Pinatubo case. Compared to an eruption followed by a period of westerly QBO, such easterly QBO eruptions are quite different, with meridional transport to mid- and high-latitudes occurring later, and at higher altitude, with a consequent decrease in cross-tropopause removal from the stratosphere, and therefore longer decay timescale. Comparing the model-calculated e-folding time of the volcanic aerosol mass during the first year after the eruptions, an increase is found from 8.1 and 10.3 months for El Chichón and Agung (QBO westerly shear), to 14.6 and 30.7 months for Pinatubo and Ruiz (QBO easterly shear). The corresponding e-folding time of the global-mean radiative flux changes goes from 9.1 and 8.0 months for El Chichón and Agung, to 28.7 and 24.5 months for Pinatubo and Ruiz. © 2016 by the authors."
"7005755107;7003686951;7005216212;54390358500;7003401367;57189490508;6506725113;","Ocean colour opportunities from Meteosat Second and Third Generation geostationary platforms",2016,"10.5194/os-12-703-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971493176&doi=10.5194%2fos-12-703-2016&partnerID=40&md5=2429f3eae348ec861a84d7b2a2bbeb62","Ocean colour applications from medium-resolution polar-orbiting satellite sensors have now matured and evolved into operational services. These applications are enabled by the Sentinel-3 OLCI space sensors of the European Earth Observation Copernicus programme and the VIIRS sensors of the US Joint Polar Satellite System programme. Key drivers for the Copernicus ocean colour services are the national obligations of the EU member states to report on the quality of marine, coastal and inland waters for the EU Water Framework Directive and Marine Strategy Framework Directive. Further applications include CO2 sequestration, carbon cycle and climate, fisheries and aquaculture management, near-real-time alerting to harmful algae blooms, environmental monitoring and forecasting, and assessment of sediment transport in coastal waters. Ocean colour data from polar-orbiting satellite platforms, however, suffer from fractional coverage, primarily due to clouds, and inadequate resolution of quickly varying processes. Ocean colour remote sensing from geostationary platforms can provide significant improvements in coverage and sampling frequency and support new applications and services. EUMETSAT's SEVIRI instrument on the geostationary Meteosat Second Generation platforms (MSG) is not designed to meet ocean colour mission requirements, however, it has been demonstrated to provide valuable contribution, particularly in combination with dedicated ocean colour polar observations. This paper describes the ongoing effort to develop operational ocean colour water turbidity and related products and user services from SEVIRI. SEVIRI's multi-temporal capabilities can benefit users requiring improved local-area coverage and frequent diurnal observations. A survey of user requirements and a study of technical capabilities and limitations of the SEVIRI instruments are the basis for this development and are described in this paper. The products will support monitoring of sediment transport, water clarity, and tidal dynamics by providing hourly coverage and long-term time series of the diurnal observations. Further products and services are anticipated from EUMETSAT's FCI instruments on Meteosat Third Generation satellites (MTG), including potential chlorophyll a products. © Author(s) 2016."
"6602182223;55173596300;55329113100;6505805689;35329672300;57205638870;57208121852;","Will a perfect model agree with perfect observations? The impact of spatial sampling",2016,"10.5194/acp-16-6335-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971373720&doi=10.5194%2facp-16-6335-2016&partnerID=40&md5=f7c1e7c52b809b271b833eb3893eed89","The spatial resolution of global climate models with interactive aerosol and the observations used to evaluate them is very different. Current models use grid spacings of ∼ 200km, while satellite observations of aerosol use so-called pixels of ∼ 10km. Ground site or airborne observations relate to even smaller spatial scales. We study the errors incurred due to different resolutions by aggregating high-resolution simulations (10km grid spacing) over either the large areas of global model grid boxes (""perfect"" model data) or small areas corresponding to the pixels of satellite measurements or the field of view of ground sites (""perfect"" observations). Our analysis suggests that instantaneous root-mean-square (RMS) differences of perfect observations from perfect global models can easily amount to 30-160%, for a range of observables like AOT (aerosol optical thickness), extinction, black carbon mass concentrations, PM2.5, number densities and CCN (cloud condensation nuclei). These differences, due entirely to different spatial sampling of models and observations, are often larger than measurement errors in real observations. Temporal averaging over a month of data reduces these differences more strongly for some observables (e.g. a threefold reduction for AOT), than for others (e.g. a twofold reduction for surface black carbon concentrations), but significant RMS differences remain (10-75%). Note that this study ignores the issue of temporal sampling of real observations, which is likely to affect our present monthly error estimates. We examine several other strategies (e.g. spatial aggregation of observations, interpolation of model data) for reducing these differences and show their effectiveness. Finally, we examine consequences for the use of flight campaign data in global model evaluation and show that significant biases may be introduced depending on the flight strategy used. © Author(s) 2016."
"56304460900;55742229800;57204307377;38863214100;57189308385;55119602800;55656837900;","EFFECTS of OBLIQUITY on the HABITABILITY of EXOPLANETS AROUND M DWARFS",2016,"10.3847/2041-8205/823/1/L20","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971538935&doi=10.3847%2f2041-8205%2f823%2f1%2fL20&partnerID=40&md5=0a7a53460bd0b9210e644a49084951e2","Most previous studies on how obliquity affects planetary habitability focused on planets around Sun-like stars. Their conclusions may not be applicable to habitable planets around M dwarfs due to the tidal-locking feature and associated insolation pattern of these planets. Here we use a comprehensive three-dimensional atmospheric general circulation model to investigate this issue. We find that the climates of planets with higher obliquities are generally warmer, consistent with previous studies. The mechanism of warming is, however, completely different. Significant reduction of low clouds, instead of sea-ice cover, within the substeller region (which moves if the obliquity is non-zero) is the key in warming M-dwarf planets with high obliquities. For a total insolation of 1237 W m-2, the climate warms by 21 K when the obliquity increases from 0° to 90°. Correspondingly, the runaway greenhouse inner edge of the habitable zone shifts outward from 2500 to 2100 W m-2. The moist greenhouse inner edge, based on our crude estimation, shifts less, from 2180 to 2075 W m-2. Near the outer edge, in contrast, the climates of planets with higher obliquities are colder due to their reduced ability to maintain a hotspot at the surface. Therefore, the outer edge moves inward when obliquity is increased, opposite to the finding of previous studies on planets around Sun-like stars. Our results thus indicate that the habitable zone for M dwarfs narrows if the obliquity of their planets increases. © 2016. The American Astronomical Society. All rights reserved.."
"55887849100;22982762300;55887389300;57189216844;55887007400;57189211478;57189221105;56195765400;36618250200;57189226399;55037487700;40561553100;36938030400;24546705400;","Earth's albedo variations 1998-2014 as measured from ground-based earthshine observations",2016,"10.1002/2016GL068025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966393324&doi=10.1002%2f2016GL068025&partnerID=40&md5=c2ed814ec358ee1d6102954f7db7f57a","The Earth's albedo is a fundamental climate parameter for understanding the radiation budget of the atmosphere. It has been traditionally measured not only from space platforms but also from the ground for 16 years from Big Bear Solar Observatory by observing the Moon. The photometric ratio of the dark (earthshine) to the bright (moonshine) sides of the Moon is used to determine nightly anomalies in the terrestrial albedo, with the aim of quantifying sustained monthly, annual, and/or decadal changes. We find two modest decadal scale cycles in the albedo, but with no significant net change over the 16 years of accumulated data. Within the evolution of the two cycles, we find periods of sustained annual increases, followed by comparable sustained decreases in albedo. The evolution of the earthshine albedo is in remarkable agreement with that from the Clouds and the Earth's Radiant Energy System instruments, although each method measures different slices of the Earth's Bond albedo. © 2016. American Geophysical Union. All Rights Reserved."
"7201784177;28367935500;","What can moist thermodynamics tell us about circulation shifts in response to uniform warming?",2016,"10.1002/2016GL068712","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84970044546&doi=10.1002%2f2016GL068712&partnerID=40&md5=8ed402a28ad09382ba63ad0d8cc9f19a","Aquaplanet simulations exhibit a robust expansion of the Hadley cell and poleward jet shift in response to uniform warming of sea surface temperature. Here moist thermodynamic and dynamic frameworks are combined to make predictions of circulation responses to warming. We show Clausius-Clapeyron (CC) scaling of specific humidity with warming predicts an expansion of the Hadley circulation according to convective quasi-equilibrium dynamics. A poleward jet shift follows from the control-climate relationship between the Hadley cell edge and jet stream position. CC scaling of specific humidity with warming also predicts decreased diffusivity and a poleward shift of the latitude of maximum latent and dry static energy transport according to mixing-length theory. Finally, atmospheric cloud radiative changes shift the latitude of maximum energy transport poleward in most models. Our results show moist thermodynamics can predict meridional shifts of the circulation when combined with dynamical frameworks; however, additional feedbacks are important for the simulated response. © 2016. American Geophysical Union. All Rights Reserved."
"6603422104;55838659500;55366637500;16202694600;7004060399;","Midlatitude cloud shifts, their primary link to the Hadley cell, and their diverse radiative effects",2016,"10.1002/2016GL068242","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992311455&doi=10.1002%2f2016GL068242&partnerID=40&md5=bdc359b7fa08344756d456033dc1cf9b","We investigate the interannual relationship among clouds, their radiative effects, and two key indices of the atmospheric circulation: the latitudinal positions of the Hadley cell edge and the midlatitude jet. From reanalysis data and satellite observations, we find a clear and consistent relationship between the width of the Hadley cell and the high cloud field, statistically significant in nearly all regions and seasons. In contrast, shifts of the midlatitude jet correlate significantly with high cloud shifts only in the North Atlantic region during the winter season. While in that region and season poleward high cloud shifts are associated with shortwave radiative warming, over the Southern Oceans during all seasons they are associated with shortwave radiative cooling. Finally, a trend analysis reveals that poleward high cloud shifts observed over the 1983-2009 period are more likely related to Hadley cell expansion, rather than poleward shifts of the midlatitude jets. © 2016. American Geophysical Union. All Rights Reserved."
"8627503500;35547214900;7005941690;6602407753;56423657500;35491260500;7202016984;8258673100;7202108879;","An overview of the CATS level 1 processing algorithms and data products",2016,"10.1002/2016GL068006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966441204&doi=10.1002%2f2016GL068006&partnerID=40&md5=8bd474894d0614092a9253dcf2230bc9","The Cloud-Aerosol Transport System (CATS) is an elastic backscatter lidar that was launched on 10 January 2015 to the International Space Station (ISS). CATS provides both space-based technology demonstrations for future Earth Science missions and operational science measurements. This paper outlines the CATS Level 1 data products and processing algorithms. Initial results and validation data demonstrate the ability to accurately detect optically thin atmospheric layers with 1064 nm nighttime backscatter as low as 5.0E-5 km-1 sr-1. This sensitivity, along with the orbital characteristics of the ISS, enables the use of CATS data for cloud and aerosol climate studies. The near-real-time downlinking and processing of CATS data are unprecedented capabilities and provide data that have applications such as forecasting of volcanic plume transport for aviation safety and aerosol vertical structure that will improve air quality health alerts globally. © Published 2016. American Geophysical Union. This article is a US Government work and is in the public domain in the United States of America."
"56448886400;57217779740;57079154800;","Detection of trends in days with thunderstorms in Iran over the past five decades",2016,"10.1016/j.atmosres.2015.12.022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955604159&doi=10.1016%2fj.atmosres.2015.12.022&partnerID=40&md5=4b3310f725581935f070ce803b303989","Thunderstorms, which usually occur when there are cumulonimbus (Cb) clouds in the sky, can be a natural hazard if they are severe. Most previous studies have focused on the physical and dynamic structure of thunderstorms, with little focus on exploring the trends of thunderstorm occurrence. In this paper, the time series of days with thunderstorms were studied at 30 synoptic stations in Iran during the past five decades (1961 to 2010). The non-parametric Mann-Kendall statistical method was the main approach employed since it is very useful in hydro-meteorological studies. The results of this study showed that the trend of days with thunderstorms in Iran was positive in most parts of the country for all months of the year. The largest area with positive and significant trends occurred in April and May, especially in the northwestern and northern parts of Iran. Based on the annual time series, more than 90% of the country's area had positive (significant or non-significant) trends. In addition, no significant negative trends were observed in days with thunderstorms for any months of the year in the study region. This research supports the hypothesis that climate change can have significant effects on extreme atmospheric phenomena. Additional research is necessary to explore the climatic and physical causes of the trends presented in this study. © 2016 Elsevier B.V."
"37087012900;12144198300;57205397413;6701729202;","A synthetic data set of high-spectral-resolution infrared spectra for the Arctic atmosphere",2016,"10.5194/essd-8-199-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969749436&doi=10.5194%2fessd-8-199-2016&partnerID=40&md5=cbe675f0ea1469a73aef9595ced3f674","Cloud microphysical and macrophysical properties are critical for understanding the role of clouds in climate. These properties are commonly retrieved from ground-based and satellite-based infrared remote sensing instruments. However, retrieval uncertainties are difficult to quantify without a standard for comparison. This is particularly true over the polar regions, where surface-based data for a cloud climatology are sparse, yet clouds represent a major source of uncertainty in weather and climate models. We describe a synthetic high-spectralresolution infrared data set that is designed to facilitate validation and development of cloud retrieval algorithms for surface-and satellite-based remote sensing instruments. Since the data set is calculated using pre-defined cloudy atmospheres, the properties of the cloud and atmospheric state are known a priori. The atmospheric state used for the simulations is drawn from radiosonde measurements made at the North Slope of Alaska (NSA) Atmospheric Radiation Measurement (ARM) site at Barrow, Alaska (71.325° N, 156.615° W), a location that is generally representative of the western Arctic. The cloud properties for each simulation are selected from statistical distributions derived from past field measurements. Upwelling (at 60 km) and downwelling (at the surface) infrared spectra are simulated for 260 cloudy cases from 50 to 3000 cm-1 (3.3 to 200 μm) at monochromatic (line-by-line) resolution at a spacing of ∼0.01 cm-1 using the Line-by-line Radiative Transfer Model (LBLRTM) and the discrete-ordinate-method radiative transfer code (DISORT). These spectra are freely available for interested researchers from the NSF Arctic Data Center data repository (doi:10.5065/D61J97TT). © 2016 Author(s)."
"56219012200;56624502400;55886067800;57202531041;26023140500;55672593500;57189340211;57189342126;55703016100;7006614214;6506606807;","The libRadtran software package for radiative transfer calculations (version 2.0.1)",2016,"10.5194/gmd-9-1647-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969567799&doi=10.5194%2fgmd-9-1647-2016&partnerID=40&md5=7307fa34c9ebf8e0ceb62f28a33eef72","libRadtran is a widely used software package for radiative transfer calculations. It allows one to compute (polarized) radiances, irradiance, and actinic fluxes in the solar and thermal spectral regions. libRadtran has been used for various applications, including remote sensing of clouds, aerosols and trace gases in the Earth's atmosphere, climate studies, e.g., for the calculation of radiative forcing due to different atmospheric components, for UV forecasting, the calculation of photolysis frequencies, and for remote sensing of other planets in our solar system. The package has been described in Mayer and Kylling (2005). Since then several new features have been included, for example polarization, Raman scattering, a new molecular gas absorption parameterization, and several new parameterizations of cloud and aerosol optical properties. Furthermore, a graphical user interface is now available, which greatly simplifies the usage of the model, especially for new users. This paper gives an overview of libRadtran version 2.0.1 with a focus on new features. Applications including these new features are provided as examples of use. A complete description of libRadtran and all its input options is given in the user manual included in the libRadtran software package, which is freely available at http://www.libradtran.org. © 2016 Author(s)."
"7007021059;7003976079;8918407000;13405561000;36187387300;8397494800;55686667100;10241462700;13402835300;7404142321;7201485519;","Robustness, uncertainties, and emergent constraints in the radiative responses of stratocumulus cloud regimes to future warming",2016,"10.1007/s00382-015-2750-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84940180949&doi=10.1007%2fs00382-015-2750-7&partnerID=40&md5=18ff867579d09f7d2d4e23e1040ee89d","Future responses of cloud regimes are analyzed for five CMIP5 models forced with observed SSTs and subject to a patterned SST perturbation. Correlations between cloud properties in the control climate and changes in the warmer climate are investigated for each of a set of cloud regimes defined using a clustering methodology. The only significant (negative) correlation found is in the in-regime net cloud radiative effect for the stratocumulus regime. All models overestimate the in-regime albedo of the stratocumulus regime. Reasons for this bias and its relevance to the future response are investigated. A detailed evaluation of the models’ daily-mean contributions to the albedo from stratocumulus clouds with different cloud cover fractions reveals that all models systematically underestimate the relative occurrence of overcast cases but overestimate those of broken clouds. In the warmer climate the relative occurrence of overcast cases tends to decrease while that of broken clouds increases. This suggests a decrease in the climatological in-regime albedo with increasing temperature (a positive feedback); this is opposite to the feedback suggested by the analysis of the bulk in-regime albedo. Furthermore we find that the inter-model difference in the sign of the in-cloud albedo feedback is consistent with the difference in sign of the in-cloud liquid water path response, and there is a strong positive correlation between the in-regime liquid water path in the control climate and its response to warming. We therefore conclude that further breakdown of the in-regime properties into cloud cover and in-cloud properties is necessary to better understand the behavior of the stratocumulus regime. Since cloud water is a physical property and is independent of a model’s radiative assumptions, it could potentially provide a useful emergent constraint on cloud feedback. © 2015, © Crown Copyright as represented by the Met Office 2015."
"7201504886;55883785100;57206156792;57169773100;23492864500;12753020100;57189623556;57189623746;6508290106;54881971400;7007020226;","The Barbados cloud observatory: Anchoring investigations of clouds and circulation on the edge of the itcz",2016,"10.1175/BAMS-D-14-00247.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973503081&doi=10.1175%2fBAMS-D-14-00247.1&partnerID=40&md5=0cddf22127cfd157ea9321e04bb411c4","The Barbados Cloud Observatory advances understanding of clouds, circulation, and climate sensitivity through sustained observations on the edge of the intertropical convergence zone (ITCZ). The seasonal migration of the ITCZ subjects Barbados to a wide variety of tropical circulation systems, including the occasional hurricane; Tomas formed over the BCO in 2010. Subsidence prevails during the dry winter months from December to June, and low-level convergence supports convection in a wet season that peaks in October but lasts from June to December."
"7004934146;7202485447;","What causes observed fog trends: Air quality or climate change?",2016,"10.4209/aaqr.2015.05.0353","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964199295&doi=10.4209%2faaqr.2015.05.0353&partnerID=40&md5=37bdf394173f2b20345176ea602b778a","Fog is a situation when the visual range, which is the horizontal visibility, is reduced to less than 1000 m near the Earth’s surface by the presence of cloud droplets. Fog trend analyses are reported in the literature for hundreds of stations worldwide, the majority of which showing a considerable reduction of fog. Although fog is often associated with conditions at which cloud condensation nuclei had been activated at rH (relative humidity) > 100% and rapid growth had lead to the formation of fog droplets, this study focusses on urban air masses and conditions when rH is just below 100%. Mie scattering analysis shows that fog can form under such conditions and the reduction of the visual range is mainly caused by submicron aerosol particles which grow to diameters around 1 μm through deliquescence. The liquid water content itself is poorly correlated with the visual range. Assuming equilibrium conditions, both an increase of the air temperature and a reduction of the aerosol particle concentration lead to reductions of fog. In our example case, the increment for a temperature increase by 0.1°C had about the same effect as the reduction of aerosol concentrations by 10%. Care must be taken in projecting this result to actual conditions because the system is non-linear. However, physical evidence is presented which confirms that both climate change and an improvement of air quality are mechanisms that can contribute to the reduction of fog. © Taiwan Association for Aerosol Research."
"36165663600;6602908667;16230028100;","Reproducibility of summer precipitation over northern Eurasia in CMIP5 multiclimate models",2016,"10.1175/JCLI-D-15-0480.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966349568&doi=10.1175%2fJCLI-D-15-0480.1&partnerID=40&md5=c3c7fd32a76be01c19cb83f25ad3fc37","Reproducibility of summer precipitation over northern Eurasia in climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) is evaluated in comparison with several observational and reanalysis datasets. All CMIP5 models under- and overestimate precipitation over western and eastern Eurasia, respectively, and the reproducibility measured using the Taylor skill score is largely determined by the severity of these west-east precipitation biases. The following are the two possible causes for the precipitation biases: Very little cloud cover and very strong local evaporation-precipitation coupling. The models underestimate cloud cover over Eurasia, allowing too much sunshine and leading to a warm bias at the surface. The associated cyclonic circulation biases in the lower troposphere weaken the modeled moisture transport from the Atlantic to western Eurasia and enhance the northward moisture flux along the eastern coast. Once the dry west and wet east biases appear in the models, they become amplified because of stronger evaporation-precipitation coupling. The CMIP5 models reproduce precipitation events well over a time scale of several days, including the associated low pressure systems and local convection. However, the modeled precipitation events are relatively weaker over western Eurasia and stronger over eastern Eurasia compared to the observations, and these are consistent with the biases found in the seasonal average fields. © 2016 American Meteorological Society."
"56803691500;7003466102;","Sampling errors in satellite-derived infrared sea-surface temperatures. Part I: Global and regional MODIS fields",2016,"10.1016/j.rse.2016.02.026","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958243775&doi=10.1016%2fj.rse.2016.02.026&partnerID=40&md5=cdbb57191be0e59de5f5e6f4bd46da6a","Long time series of accurate Sea Surface Temperatures (SSTs) are needed to resolve subtle signals that may be indicative of a changing climate. Motivated by the stringent requirements on SST accuracy required for Climate Data Records (CDR) we quantify sampling errors in satellite SSTs. Infrared sensors, including the Moderate Resolution Imaging Spectroradiometer (MODIS), have sampling errors caused by incomplete coverage primarily due to clouds and inter-swath gaps (gaps between successive swaths/orbits). Unlike retrieval errors, the sampling errors are introduced when calculating mean values and in generating gap-free SST fields. We generate MODIS-sampled SST fields by superimposing MODIS cloud masks on top of the Multi-scale Ultrahigh Resolution (MUR) SST field for the same day. Based on the MODIS-sampled fields, we calculate sampling errors at different temporal and spatial resolutions to examine the impacts at different scales. Our results indicate that sampling errors are significant, more so in the high latitudes, especially the Arctic. The 30°N-30°S zonal band is found to have the smallest errors; a notable exception is the persistent negative errors found in the Tropical Instability Wave area, where the mesoscale ocean-atmosphere interaction leads to a more frequently satellite sampling above the cold sections of the wave area. The global mean sampling error is generally positive and increases approximately exponentially with missing data fraction at a fixed averaging interval, while error variability is mainly controlled by SST variability. Areas with persistent cloud cover have large sampling errors in temporally averaged SSTs. We conclude that the sampling error can be an important or even dominant component of the error budget of mean and gap-free SST fields. Climate data generation and interpretation of satellite-derived SST CDRs and their application must be conducted with due regard to the sampling error. © 2016 Elsevier Inc."
"37017375800;7004713318;6603312615;36017092100;","Flow recession as a driver of the morpho-texture of braided streams",2016,"10.1002/esp.3861","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84950244230&doi=10.1002%2fesp.3861&partnerID=40&md5=14f93f5a2f575261df84b898436981d1","Braiding has been widely studied in humid-temperate climates though rarely in arid environments. Morpho-texture of braided streams refers to the morphological-textural organization in a braid-cell (stream section including bars, anabranches and chutes) that may strongly relate to different processes and hydrological regimes. The objective of this study is to compare the morpho-texture of braided streams governed by diverse flow recessions in different climates. Measurements were conducted in the wadis Ze'elim and Rahaf, southeast hyper-arid Israel, in the Mediterranean Barranca-de-los-Pinos, central Spain and in humid-temperate braided systems, the La-Bléone River, Haute-Provence, France and in the Saisera and Cimoliana torrents, northeast Italy. Terrestrial laser scanning was used to produce point clouds and high resolution digital elevation models of the braid-cells. Wet braid-cells in humid-temperate environments were surveyed by a Total Station. Roughness and the upper tail of grain size distributions were derived from the scanned point clouds or from Wolman sampling. We found that anabranches are commonly finer-grained than the bars in dryland systems and in semi-arid sandy braided systems, contrary to the humid-temperate braided systems. In both climates, chutes are similar or coarser-grained than the bars which they dissect, in accordance with their steeper gradients due to the considerable bar-anabranch relief. The Saisera's morpho-texture is similar to that of the dryland braided channels, despite the very humid-temperate environment in which it is located, due to its short-lived, ephemeral type hydrograph. Hydrograph shape, specifically the duration of flow recession, typical of a climate but not confined to it, determines the morpho-texture of braided streams and the textural differentiation between a depositional bar and the adjacent anabranches. The morpho-texture of chutes and bars results also from local erosional processes affected by local topography, i.e. ungraded longitudinal profiles, and is not solely determined by flow recession. This new morpho-textural model enables identifying primary depositional and erosional braiding processes. © 2016 John Wiley & Sons, Ltd."
"57189050879;7101878692;","Seasonal relationship between meteorological conditions and surface ozone in Korea based on an offline chemistry-climate model",2016,"10.1016/j.apr.2015.10.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964957504&doi=10.1016%2fj.apr.2015.10.020&partnerID=40&md5=c643e58dd68c1e6bac49251d89a57df3","Tropospheric ozone plays an important role in climate variation and air quality, and it has seen a dramatic rise in East Asia due to the region's rapid economic growth. The relationship between meteorological conditions and surface ozone in Korea varies seasonally, and to obtain a better understanding of this process, this study performed offline simulations using a climate-chemistry model. The model represented the observed annual cycle of surface ozone over East Asia well, including the spring/autumn peaks and summer troughs. Increases in ozone were associated primarily with the westerly wind anomaly during spring and with surface warming during the autumn and summer. Moreover, a decrease in ozone during the summer likely resulted from the transportation of ozone-depleted air masses by anomalous southeasterly winds. Reduced cloud cover increased ozone levels significantly during all seasons except winter. The relationship between the El Niño and Southern Oscillation and ozone concentrations in Korea was also examined. Spring ozone levels tended to be elevated following mature-phase El Niño winters, whereas elevated levels during summer and autumn followed La Niña winters. © 2015 Turkish National Committee for Air Pollution Research and Control."
"8117864800;55785193100;36827679700;7405460591;","Numerical study of motion and stability of falling columnar crystals",2016,"10.1175/JAS-D-15-0219.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84965125270&doi=10.1175%2fJAS-D-15-0219.1&partnerID=40&md5=aec32ac69f6ed60a3be5022e1e6b492f","Understanding of the flow field and falling patterns of ice crystals is fundamental to cloud physics and radiative transfer, and yet the complex shape hampers a comprehensive understanding. In order to create better understanding of falling patterns of columnar crystals, this study utilizes a computational fluid dynamics package and explicitly simulates the motion as well as the flow fields. Three modes of patterns (i.e., strong damping, fluttering, and unstable modes) were identified in the space of inverse aspect ratio (q) and Reynolds number (Re). The boundary of stability depicts the ""L"" shape as found in a previous experimental study. This study newly found that the range of Re for stable motion increases with a decrease in q. Decomposition of hydrodynamic torques indicates that, for stablemode, the pressure and viscous torques acting on the lower prismfaces counteract the rotation when the inclination angle becomes 0°. The unstable motion was attributed to the pressure torque acting on the upper prism faces, which is associated with eddies that lag behind the oscillating boundary. Observed Re-q relationships of columns suggest that the strong dampingmode ismost likely to occur in the atmosphere, but the fluttering mode is also possible. Furthermore, the time scales of oscillation and damping were parameterized as a function of q and Re. The impact of the fluttering on the riming process is limited at the beginning, which supports the current formulation in numerical weather and climate models. © 2016 American Meteorological Society."
"55220443400;7408519295;57188693618;","Role of atmospheric heating over the South China Sea and western Pacific regions in modulating Asian summer climate under the global warming background",2016,"10.1007/s00382-015-2739-2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84968648344&doi=10.1007%2fs00382-015-2739-2&partnerID=40&md5=05e9eab673699030423908e8b49a5acf","The response of monsoon precipitation to global warming, which is one of the most significant climate change signals at the earth’s surface, exhibits very distinct regional features, especially over the South China Sea (SCS) and adjacent regions in boreal summer. To understand the possible atmospheric dynamics in these specific regions under the global warming background, changes in atmospheric heating and their possible influences on Asian summer climate are investigated by both observational diagnosis and numerical simulations. Results indicate that heating in the middle troposphere has intensified in the SCS and western Pacific regions in boreal summer, accompanied by increased precipitation, cloud cover, and lower-tropospheric convergence and decreased sea level pressure. Sensitivity experiments show that middle and upper tropospheric heating causes an east–west feedback pattern between SCS and western Pacific and continental South Asia, which strengthens the South Asian High in the upper troposphere and moist convergence in the lower troposphere, consequently forcing a descending motion and adiabatic warming over continental South Asia. When air–sea interaction is considered, the simulation results are overall more similar to observations, and in particular the bias of precipitation over the Indian Ocean simulated by AGCMs has been reduced. The result highlights the important role of air–sea interaction in understanding the changes in Asian climate. © 2015, The Author(s)."
"57189457127;56823583800;55930354700;12773621900;55905723500;6603585592;8407779800;","Large increases in Arctic biogenic volatile emissions are a direct effect of warming",2016,"10.1038/ngeo2692","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971350897&doi=10.1038%2fngeo2692&partnerID=40&md5=4c9fff3357eb6fd03d95ffb3233bd5f5","Biogenic volatile organic compounds are reactive gases that can contribute to atmospheric aerosol formation. Their emission from vegetation is dependent on temperature and light availability. Increasing temperature, changing cloud cover and shifting composition of vegetation communities can be expected to affect emissions in the Arctic, where the ongoing climate changes are particularly severe. Here we present biogenic volatile organic compound emission data from Arctic tundra exposed to six years of experimental warming or reduced sunlight treatment in a randomized block design. By separately assessing the emission response of the whole ecosystem, plant shoots and soil in four measurements covering the growing season, we have identified that warming increased the emissions directly rather than via a change in the plant biomass and species composition. Warming caused a 260% increase in total emission rate for the ecosystem and a 90% increase in emission rates for plants, while having no effect on soil emissions. Compared to the control, reduced sunlight decreased emissions by 69% for the ecosystem, 61-65% for plants and 78% for soil. The detected strong emission response is considerably higher than observed at more southern latitudes, emphasizing the high temperature sensitivity of ecosystem processes in the changing Arctic. © 2016 Macmillan Publishers Limited. All rights reserved."
"23977679300;14119516800;7004368198;","Sampling uncertainty in gridded sea surface temperature products and Advanced Very High Resolution Radiometer (AVHRR) Global Area Coverage (GAC) data",2016,"10.1016/j.rse.2016.02.021","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959268743&doi=10.1016%2fj.rse.2016.02.021&partnerID=40&md5=569d395bc53e7b0524c5ddd79d49825d","Sea surface temperature (SST) data are often provided as gridded products, typically at resolutions of order 0.05° from satellite observations, to reduce data volume at the request of data users and facilitate comparison against other products or models. Sampling uncertainty is introduced in gridded products where the full surface area of the ocean within a grid cell cannot be fully observed because of cloud cover. In this paper we parameterise uncertainties in SST as a function of the percentage of clear-sky pixels available and the SST variability in that subsample. This parameterisation is developed from Advanced Along Track Scanning Radiometer (AATSR) data, but is applicable to all gridded L3U SST products at resolutions of 0.05-0.1°, irrespective of instrument and retrieval algorithm, provided that instrument noise propagated into the SST is accounted for. We also calculate the sampling uncertainty of ~. 0.04 K in global area coverage (GAC) Advanced Very High Resolution Radiometer (AVHRR) products, using related methods. © 2016 Elsevier Inc.."
"16028133700;26635271700;6506644040;23091448100;8782763500;","Slope position influences vegetation-atmosphere interactions in a tropical montane cloud forest",2016,"10.1016/j.agrformet.2016.02.012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959432415&doi=10.1016%2fj.agrformet.2016.02.012&partnerID=40&md5=1e1ddf4fd2d7d1f93d2ad51655203f4e","Throughout a single day, the microclimatic conditions in tropical montane cloud forests vary from strong solar radiation with simultaneous strong atmospheric water demand (high vapor pressure deficit, VPD, values), followed quickly by clouds and fog events drastically reducing both of these environmental variables. Due to the complex topography and weather patterns in these regions, microclimate, including fog events, can vary strongly across very small spatial scales as well, leading to a highly dynamic and compelling environment to examine how environmental variables influence tree water use across space and time. Due to this variation, the present study examines how environmental drivers of tree water use varies across three slope positions (upslope, midslope, low-slope) in a tropical montane cloud forest in Veracruz, Mexico. Measurements of sap flow using the heat ratio method were conducted on three dominant canopy species along with simultaneous measurements of microclimate within each site. To assess the relative importance of microclimatic variables in explaining tree water use across diurnal periods, data were separated into day and night periods and fog and clear events. Multiple regression models were conducted for each tree with input variables of VPD, solar radiation, air temperature, shallow soil moisture, deep soil moisture, and leaf wetness. We found that VPD explained a large majority of the variation in tree water use during daytime fog periods, particularly at the upslope and midslope sites. During nighttime periods, VPD was the dominant driver of water use variation during clear periods while a combination of VPD and leaf wetness explained variation during night, fog periods. Additionally, tree water use was more decoupled from environmental variables at the low-slope site. Finally, a separation of model components into fog and clear periods improved model outputs particularly at low flow conditions, highlighting the differential interactions between tree water use and environment during night and fog periods. Results from this study provide new insight into the importance of fog events, low VPD, and leaf surface wetting at controlling tree water use in cloud forests. The variation in drivers of water use across short spatial scales demonstrate the importance of considering individual and species level variation across fog and clear periods in predicting physiological responses of species to climate in cloud forests. © 2016 Elsevier B.V."
"55229376100;6507671561;6603035923;","Thermal light curves of Earth-like planets: 1. Varying surface and rotation on planets in a terrestrial orbit",2016,"10.1016/j.icarus.2015.12.050","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959347083&doi=10.1016%2fj.icarus.2015.12.050&partnerID=40&md5=8febf28324f29fec928a46df46101813","The integrated thermal emission of an exoplanet and its variations along the orbital motion can carry information about the climatic conditions and the rotation of the planet. In this study, we use the LMDZ 3D Global Climate Model (GCM) to simulate the climate of a synthetic Earth and three quasi-Earth configurations: a slowly rotating Earth, an ocean-covered Earth and its snowball counterpart. We also generate the time-dependent broadband thermal emission of the planet from these simulations. In a first step, we validate the model by comparing the synthetic Earth emission with the actual emission of our planet as constrained by observations. Then, we determine the main properties of the climate and emission of the three Earth-like planets and compare them to those of the Earth. We show that planets with an uneven distribution of continents exhibit a maximum of emission during the summer of the hemisphere with larger continental masses, and they may exhibit a maximum of emission at apastron. Large convective clouds might form over the continents of slow rotating planets, having an important effect over their climate and their emission. We also show that, in all the modeled cases, the equilibrium temperature, the Bond albedo and the rotation period can in theory be retrieved from the light curve by a distant observer. The values obtained at transiting geometries have a low deviation from the global values for cases with an axis tilt similar to that of the Earth, and we are able to distinguish between the four planets presented here by the data obtained from their light curves. However, this might not be the case under different conditions. © 2016 Elsevier Inc.."
"9436114900;54986194000;7005632987;55663671600;15737545100;6506314887;","Simulation of bulk aerosol direct radiative effects and its climatic feedbacks in South Africa using RegCM4",2016,"10.1016/j.jastp.2016.02.013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958981938&doi=10.1016%2fj.jastp.2016.02.013&partnerID=40&md5=faf38bfb3521630b27a2a0059a2a865a","In this study, 12 year runs of the Regional Climate Model (RegCM4) have been used to analyze the bulk aerosol radiative effects and its climatic feedbacks in South Africa. Due to the geographical locations where the aerosol potential source regions are situated and the regional dynamics, the South African aerosol spatial-distribution has a unique feature. Across the west and southwest areas, desert dust particles are dominant. However, sulfate and carbonaceous aerosols are primarily distributed over the east and northern regions of the country. Analysis of the Radiative Effects (RE) shows that in South Africa the bulk aerosols play a role in reducing the net radiation absorbed by the surface via enhancing the net radiative heating in the atmosphere. Hence, across all seasons, the bulk aerosol-radiation-climate interaction induced statistically significant positive feedback on the net atmospheric heating rate. Over the western and central parts of South Africa, the overall radiative feedbacks of bulk aerosol predominantly induces statistically significant Cloud Cover (CC) enhancements. Whereas, over the east and southeast coastal areas, it induces minimum reductions in CC. The CC enhancement and RE of aerosols jointly induce radiative cooling at the surface which in turn results in the reduction of Surface Temperature (ST: up to -1 K) and Surface Sensible Heat Flux (SSHF: up to -24 W/m2). The ST and SSHF decreases cause a weakening of the convectively driven turbulences and surface buoyancy fluxes which lead to the reduction of the boundary layer height, surface pressure enhancement and dynamical changes. Throughout the year, the maximum values of direct and semi-direct effects of bulk aerosol were found in areas of South Africa which are dominated by desert dust particles. This signals the need for a strategic regional plan on how to reduce the dust production and monitoring of the dust dispersion as well as it initiate the need of further research on different aspects of dust particle in South Africa. © 2016 Elsevier Ltd."
"16480666100;55537426400;6603196127;","Surface arctic amplification factors in CMIP5 models: Land and oceanic surfaces and seasonality",2016,"10.1175/JCLI-D-15-0497.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966312444&doi=10.1175%2fJCLI-D-15-0497.1&partnerID=40&md5=0026892260ec1f2e327ecfe72bfe0e5a","Arctic amplification (AA) is a major characteristic of observed global warming, yet the different mechanisms responsible for it and their quantification are still under investigation. In this study, the roles of different factors contributing to local surface warming are quantified using the radiative kernel method applied at the surface after 100 years of global warming under a representative concentration pathway 4.5 (RCP4.5) scenario simulated by 32 climate models from phase 5 of the Coupled Model Intercomparison Project. The warming factors and their seasonality for land and oceanic surfaces were investigated separately and for different domains within each surface type where mechanisms differ. Common factors contribute to both land and oceanic surface warming: Tropospheric-mean atmospheric warming and greenhouse gas increases (mostly through water vapor feedback) for both tropical and Arctic regions, nonbarotropic warming and surface warming sensitivity effects (negative in the tropics, positive in the Arctic), and warming cloud feedback in the Arctic in winter. Some mechanisms differ between land and oceanic surfaces: Sensible and latent heat flux in the tropics, albedo feedback peaking at different times of the year in the Arctic due to different mean latitudes, a very large summer energy uptake and winter release by the Arctic Ocean, and a large evaporation enhancement in winter over the Arctic Ocean, whereas the peak occurs in summer over the ice-free Arctic land. The oceanic anomalous energy uptake and release is further studied, suggesting the primary role of seasonal variation of oceanic mixed layer temperature changes. © 2016 American Meteorological Society."
"36118287200;7101661890;","Evolution of the diurnal precipitation cycle with the passage of a Madden-Julian oscillation event through the Maritime Continent",2016,"10.1175/MWR-D-15-0326.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966293848&doi=10.1175%2fMWR-D-15-0326.1&partnerID=40&md5=6c9e7eaa914e3fa937b51b27196bdae7","Changes in the diurnal precipitation cycle as the Madden-Julian oscillation (MJO) propagates through the Maritime Continent are investigated to explore the processes behind seaward-propagating precipitation northeast of New Guinea. Satellite rainfall estimates from TRMM 3B42 and the Climate Prediction Center morphing technique (CMORPH) are combined with simulations from the Weather Research and Forecasting (WRF) Model with a horizontal resolution of 4 km. Comparison with 24-h rain gauge measurements indicates that both satellite estimates and the WRF Model exhibit systematic biases. Despite these biases, the changing patterns of offshore precipitation with the passage of the MJO show good consistency between satellite estimates and the WRF Model. In the few days prior to the main MJO envelope, light background wind, relatively clear skies, and an increasingly moist environment promote favorable conditions for the diurnal precipitation cycle. Two distinct processes are identified: 100-200 km from the coast, precipitation moves offshore as a squall line with a propagation speed of 3-5 m s-1. Farther offshore, precipitation propagates with a speed close to 18 m s-1 and is associated with an inertia-gravity wave generated by diurnally oscillating heating from radiative and moist convective processes over the land. A gravity wave signature is evident even after the MJO active period when there is little precipitation. By correcting for the background flow perpendicular to the coast, potential temperature anomalies for the lead-up, active, and follow-on MJO periods are shown to collapse to a remarkably invariant shape for a given time of day. © 2016 American Meteorological Society."
"17344070800;6603741479;","Linking zooplankton richness with energy input and insularity along altitudinal and latitudinal gradients",2016,"10.1002/lno.10263","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969182539&doi=10.1002%2flno.10263&partnerID=40&md5=1c1c9bc0c58278680e87e558837890ec","Altitudinal and latitudinal gradients are excellent venues for investigating the direct and indirect effects of air temperature, solar irradiance, and insularity on spatial patterns of aquatic biodiversity. The findings can be used to predict how lake communities will respond to increasingly extreme climate events. We explored hypotheses of energy/climate, geography, and glacial history explaining patterns in species richness in a historical dataset of crustacean zooplankton communities from 436 lakes in the Canadian Rocky Mountains. GIS-based estimates of solar and thermal energy inputs combined with habitat area and insularity provided the best prediction of local species richness. Energetic and geographic factors explained a moderate proportion of the total variation in species richness (Generalized R2=0.50), and were sufficient to account for both altitudinal and latitudinal gradients in zooplankton diversity. History of deglaciation was not supported as a predictor of patterns in species richness. A post hoc analysis with a smaller dataset also found strong support for lake pH, and some support for fish presence as predictors of species richness, but these only increased the proportion of the total variation explained very slightly relative to the model including only energetic and geographic factors (Generalized R2=0.55 vs. 0.53). Our findings highlight the multiplicity of local and regional factors of zooplankton species richness in mountain lakes, forecasting that it will increase under a scenario of warmer and drier (i.e., less cloud cover) conditions, especially in high connectivity lakes that cease to be fed by rapidly disappearing glaciers. © 2016 Association for the Sciences of Limnology and Oceanography.."
"7004364155;13204619900;8977001000;56493740900;6602098362;7403282069;7201443624;","Observational constraints on atmospheric and oceanic cross-equatorial heat transports: revisiting the precipitation asymmetry problem in climate models",2016,"10.1007/s00382-015-2766-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84937899110&doi=10.1007%2fs00382-015-2766-z&partnerID=40&md5=82b62d809fd8a943ce08a151532c8df1","Satellite based top-of-atmosphere (TOA) and surface radiation budget observations are combined with mass corrected vertically integrated atmospheric energy divergence and tendency from reanalysis to infer the regional distribution of the TOA, atmospheric and surface energy budget terms over the globe. Hemispheric contrasts in the energy budget terms are used to determine the radiative and combined sensible and latent heat contributions to the cross-equatorial heat transports in the atmosphere (AHTEQ) and ocean (OHTEQ). The contrast in net atmospheric radiation implies an AHTEQ from the northern hemisphere (NH) to the southern hemisphere (SH) (0.75 PW), while the hemispheric difference in sensible and latent heat implies an AHTEQ in the opposite direction (0.51 PW), resulting in a net NH to SH AHTEQ (0.24 PW). At the surface, the hemispheric contrast in the radiative component (0.95 PW) dominates, implying a 0.44 PW SH to NH OHTEQ. Coupled model intercomparison project phase 5 (CMIP5) models with excessive net downward surface radiation and surface-to-atmosphere sensible and latent heat transport in the SH relative to the NH exhibit anomalous northward AHTEQ and overestimate SH tropical precipitation. The hemispheric bias in net surface radiative flux is due to too much longwave surface radiative cooling in the NH tropics in both clear and all-sky conditions and excessive shortwave surface radiation in the SH subtropics and extratropics due to an underestimation in reflection by clouds. © 2015, Springer-Verlag Berlin Heidelberg (outside the USA)."
"16426223500;13408504900;7103325318;10044631200;","Tempo-spatial characteristics of sub-daily temperature trends in mainland China",2016,"10.1007/s00382-015-2726-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84936802960&doi=10.1007%2fs00382-015-2726-7&partnerID=40&md5=f21f4cc886f3a28cef8c45fb88aafbbe","The spatial and temporal pattern of sub-daily temperature change in mainland China was analysed for the period from 1973 to 2011 using a 3-hourly dataset based on 408 stations. The increase in surface air temperature was more significant by night between 1973 and 1992, with the fastest upward trend around local midnight being about 0.27 °C/decade, while it was more significant by day between 1992 and 2011, with the fastest upward trend being about 0.46 °C/decade in mid-late morning. The season with rapid temperature increase also shifted from winter in 1973–1992 (the largest increase happened near midnight in December, 0.75 °C/decade) to spring in 1992–2011 (the largest increase happened at in the early afternoon in March, 0.82 °C/decade). The change in the spatial distributions of the sub-daily temperature trends shows that Northeast China warmed more significantly in 1973–1992 than elsewhere, but it cooled in 1992–2011, when Southwest China was the new focus of temperature increase whereas it had previously been cooling. A preliminary analysis of the possible causes implies that changes in solar radiation, cloud cover, aerosols and the observational environments near the stations might have contributed to these observed temperature changes. © 2015, The Author(s)."
"55836409900;57203367163;7003919484;55836244800;55938264900;55836901300;36342537900;23989243400;14009218600;56994248600;55938524600;57145351000;","Albedo of coastal landfast sea ice in Prydz Bay, Antarctica: Observations and parameterization",2016,"10.1007/s00376-015-5114-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959375603&doi=10.1007%2fs00376-015-5114-7&partnerID=40&md5=b9eb83bedb9d2764e33d36c10149498c","The snow/sea-ice albedo was measured over coastal landfast sea ice in Prydz Bay, East Antarctica (off Zhongshan Station) during the austral spring and summer of 2010 and 2011. The variation of the observed albedo was a combination of a gradual seasonal transition from spring to summer and abrupt changes resulting from synoptic events, including snowfall, blowing snow, and overcast skies. The measured albedo ranged from 0.94 over thick fresh snow to 0.36 over melting sea ice. It was found that snow thickness was the most important factor influencing the albedo variation, while synoptic events and overcast skies could increase the albedo by about 0.18 and 0.06, respectively. The in-situ measured albedo and related physical parameters (e.g., snow thickness, ice thickness, surface temperature, and air temperature) were then used to evaluate four different snow/ice albedo parameterizations used in a variety of climate models. The parameterized albedos showed substantial discrepancies compared to the observed albedo, particularly during the summer melt period, even though more complex parameterizations yielded more realistic variations than simple ones. A modified parameterization was developed, which further considered synoptic events, cloud cover, and the local landfast sea-ice surface characteristics. The resulting parameterized albedo showed very good agreement with the observed albedo. © 2016, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg."
"35337041800;57209630149;","Spatio-temporal variability of aerosols over East China inferred by merged visibility-GEOS-Chem aerosol optical depth",2016,"10.1016/j.atmosenv.2016.02.037","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959376467&doi=10.1016%2fj.atmosenv.2016.02.037&partnerID=40&md5=d2d63e114c59559e2e62e88ddd4e19b3","Long-term visibility measurements offer useful information for aerosol and climate change studies. Recently, a new technique to converting visibility measurements to aerosol optical depth (AOD) has been developed on a station-to-station basis (Lin et al., 2014). However, factors such as human observation differences and local meteorological conditions often impair the spatial consistency of the visibility converted AOD dataset. Here we further adopt AOD spatial information from a chemical transport model GEOS-Chem, and merge visibility inferred and modeled early-afternoon AOD over East China on a 0.667° long. × 0.5° lat. grid for 2005-2012. Comparisons with MODIS/Aqua retrieved AOD and subsequent spectral decomposition analyses show that the merged dataset successfully corrects the low bias in the model while preserving its spatial pattern, resulting in very good agreement with MODIS in both magnitude and spatio-temporal variability. The low bias is reduced from 0.10 in GEOS-Chem AOD to 0.04 in the merged data averaged over East China, and the correlation in the seasonal and interannual variability between MODIS and merged AOD is well above 0.75 for most regions. Comparisons between the merged and AERONET data also show an overall small bias and high correlation. The merged dataset reveals four major pollution hot spots in China, including the North China Plain, the Yangtze River Delta, the Pearl River Delta and the Sichuan Basin, consistent with previous works. AOD peaks in spring-summer over the North China Plain and Yangtze River Delta and in spring over the Pearl River Delta, with no distinct seasonal cycle over the Sichuan Basin. The merged AOD has the largest difference from MODIS over the Sichuan Basin. We also discuss possible benefits of visibility based AOD data that correct the sampling bias in MODIS retrievals related to cloud-free sampling and misclassified heavy haze conditions. © 2016 Elsevier Ltd."
"22982141200;7201920155;55904436200;7101751659;57203321797;","Observed trend of diurnal temperature range in the Tibetan plateau in recent decades",2016,"10.1002/joc.4517","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84948844168&doi=10.1002%2fjoc.4517&partnerID=40&md5=b73d6697ab3de761a5885cf5244db7a5","Spatial and temporal variabilities of long-term (1961–2013) diurnal temperature range (DTR) are examined in the Tibetan Plateau (TP) based on the 71 observational stations. The relative regional contributions to DTR in the TP are studied among maximum temperature, minimum temperature, total cloud cover (TCC), and atmospheric teleconnections. The regional annual mean DTR (average of the 71 stations) is 14.17° C, with a clear maximum in winter (16.35°C) and minimum in summer (12.62°C). During 1961–2013, the DTR in the TP declines before the 1980s and shows mute change afterwards, with an annual rate of −0.20° C decade-1 calculated by the Mann–Kendall method. The trend in DTR is primarily a consequence of greater warming in minimum temperature than maximum temperature. In summer, there are significant negative correlations between the TCC and DTR in the TP, suggesting that the decreases in the DTR are associated with variations of TCC in the region. The atmospheric circulation composite analysis between strongly positive and negative DTR in summer in the TP reveals that during the low DTR period the TP has more water vapour flux, stronger temperature advection, and strengthened southerly wind. This suggests that the atmospheric circulations have contributed to the trends in the DTR, but it is difficult to account for the specific contributions. Further investigations of the impact of global warming on the DTR in the TP are still required. © 2015 Royal Meteorological Society."
"35091692800;7007018426;35577912900;","Sources of bias and variability in long-term Landsat time series over Canadian boreal forests",2016,"10.1016/j.rse.2016.02.041","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978477162&doi=10.1016%2fj.rse.2016.02.041&partnerID=40&md5=9631161a008e3875241481de38afa09d","A variety of evidence suggests that the boreal forests of Canada are responding to climate change. Specifically, several studies have inferred that widespread browning trends detected in time series of the Normalized Difference Vegetation Index (NDVI) from the Advanced Very High Resolution Radiometer (AVHRR) reflect the response of boreal forests to longer growing seasons, increased summer drought stress, and higher frequency of fires. Data from the Thematic Mapper (TM5) and Enhanced Thematic Mapper Plus (ETM+) sensors onboard Landsat 5 and 7, respectively, span essentially the same time period as the AVHRR record, but provide data with substantially higher radiometric and spatial fidelity, and by extension, a much improved basis for evaluating decadal-scale trends in spectral vegetation indices such as the NDVI. However, detection of trends, which are often subtle, requires careful attention to ensure that artifacts associated with the quality and stability of inter- and intra-sensor calibration do not lead to spurious conclusions in results from time series analyses. In this paper, we use time series of TM5 and ETM+ images for fifteen sites distributed across the Canadian boreal forest zone to explore if and how sensor geometry and inter- and intra-sensor calibration affect trends in spectral vegetation indices derived from multi-decadal Landsat time series. To do this, we created annual cloud-free composites for each Landsat spectral band based on peak summer NDVI at each site from 1984 to 2011 using all available TM5 and ETM+ data. To distinguish trends arising from long term climate change from those related to disturbance, we isolated areas within each site that were undisturbed during the Landsat record, and used these locations to analyze sources of variance in time series of red reflectance, near-infrared (NIR) reflectance, the NDVI, and the Enhanced Vegetation Index (EVI). Our results highlight the challenges involved in distinguishing trends in surface properties from data artifacts caused by undetected atmospheric effects, changes in sensor view angles, and subtle radiometric differences between the TM5 and ETM+ sensors. In particular, differences in sensor view geometry across adjacent overlapping Landsat scenes cause vegetated pixels in the eastern portion of Landsat scenes to have higher reflectances in the red and NIR bands (by 5 and 6 percent, respectively) than pixels in the western portion of scenes. While this effect does not significantly change NDVI values, it does affect EVI values. We also found modest, but potentially significant, differences between the red band reflectance of each sensor, with TM5 data having 14 percent higher red reflectance on average for vegetated pixels, which can introduce spurious trends in time series that combine TM5 and ETM+ data. More generally, the results from this work demonstrate that while the 30 + year Landsat archive provides unprecedented opportunities for studying changes to the Earth's terrestrial biosphere over the last three decades, care must be taken when inferring trends in these data without considering how sources of variance unrelated to surface processes affect the integrity of Landsat time series. © 2016 Elsevier Inc."
"36080672700;29067571700;35796445300;16646815400;","Identification of airborne radioactive spatial patterns in Europe - Feasibility study using Beryllium-7",2016,"10.1016/j.jenvrad.2016.02.006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958972288&doi=10.1016%2fj.jenvrad.2016.02.006&partnerID=40&md5=315c2e12b14a4a97bb9d7bc780aa9970","The present study proposes a methodology to identify spatial patterns in airborne radioactive particles in Europe. The methodology is based on transforming the activity concentrations in the set of stations for each month (monthly index), due to the tightly spaced sampling intervals (daily to monthly), in combination with hierarchical and non-hierarchical clustering approaches, due to the lack of a priori knowledge of the number of clusters to be created. Three different hierarchical cluster methodologies are explored to set the optimal number of clusters necessary to initialize the non-hierarchical one (k-means).To evaluate this methodology, cosmogenic beryllium-7 (7Be) data, collected between 2007 and 2010 at 19 sampling stations in European Union (EU) countries and stored in the Radioactivity Environmental Monitoring (REM) database, are used. This methodology yields a solution with three distinguishable clusters (south, central and north), each with a different evolution of the 7Be monthly index. Clear differences between monthly indices are shown in both intensity and time trends, following a latitudinal distribution of the sampling stations.This cluster result is evaluated performing ANOVA analysis, considering the original 7Be activity concentrations grouped in each cluster. The statistical results (among clusters and sampling stations within clusters) confirm the spatial distribution of 7Be in Europe, and, hence, reinforce the use of this methodology. Finally, the impact of tropopause height on this grouping is successfully tested, suggesting its influence on the spatial distribution of 7Be in Europe.For airborne radioactive particles the analysis gave valuable results that improve knowledge of these atmospheric compounds in Europe. Hence, this work addresses a methodology to a grouping of airborne sampling stations, 1) allowing a better understanding of the distribution of 7Be activity concentrations in the EU, and 2) serving as a basis for further investigation of the heterogeneity of airborne radioactivity concentrations in Europe. © 2016 The Authors."
"55777297100;13613779300;7102916495;8719649000;52363531000;55984680100;7202196560;21835177200;56754435600;57119367600;57118948800;7004425841;","LiDAR canopy radiation model reveals patterns of photosynthetic partitioning in an Arctic shrub",2016,"10.1016/j.agrformet.2016.02.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958260491&doi=10.1016%2fj.agrformet.2016.02.007&partnerID=40&md5=0a86aa5c5d25f972d8dd78576b5c1686","Characterizing the wide range of light availability and photosynthetic properties throughout a plant canopy is important for modeling the exchanges of carbon, water, and nutrients between the biosphere and the atmosphere. Such characterization could be especially important in one of the world's most rapidly changing biomes - the Arctic tundra - where further warming-induced increases in the size, abundance and complexity of small arctic shrubs are projected. An improved understanding of their canopy organization could provide insights into associated climate feedbacks since multifaceted interactions between 3D canopy structure, environmental conditions, leaf physiology, and light availability affect the potentials and limitations of vegetation carbon assimilation and storage. The aim of this study was to explore new methods to elucidate evidence for photosynthetic partitioning according to light availability within a short canopy (&lt;1 m tall) of Salix pulchra exposed to near continuous sunlight at low solar angles in the Arctic tundra. Instantaneous photosynthetic photon flux density (PPFD) and daily integrated quantum flux density (Qint) were modeled from a ray-tracing algorithm for voxels (edge-length .01 m) within the canopy that were each assigned a physically based directional gap fraction (DGF) and extinction coefficient (k) from which each voxel's effective leaf area index (LAIe) was calculated. Voxel parameters for the ray-tracing model were derived from the x, y, and z locations of high spatial resolution (&lt;1 mm) three-dimensional (3D) maps of shrub canopies from terrestrial LiDAR point clouds. Two LiDAR-derived light quantification variables - modeled Qint and path-length (determined as the accumulated photon travel distance from the canopy-edge) were compared with two variables derived from traditional light quantification techniques - ceptometer derived leaf-area index (LAI), and manually measured vertical canopy depth. Insignificant relationships were observed between traditional measurements of light environment (LAI and vertical canopy depth) and TLS derived measurements (Qint and path length), suggesting wide variability among these methods. When each of four light quantification variables were compared against leaf-level variables classically associated with photosynthetic partitioning (percent nitrogen (N%), chlorophyll a to b ratio (Chl a/b), and photosynthetic capacity (Amax)), patterns suggesting photosynthetic partitioning emerged only when the LiDAR-derived 3D locations of the leaf samples were considered (Qint and path length). Statistically significant (p &lt; 0.05) trends that follow the theoretical response of leaves to light availability were observed between all three photosynthetic variables and LiDAR-derived Qint (r = 0.31, 0.46, 0.49 for N%, Chl a/b, and Amax, respectively), while 2 of 3 showed a statistically significant response to LiDAR derived path length. Only 1 of 3 photosynthetic variables showed a statistically significant response to manually measured canopy depth or ceptometer derived LAI. Results from this study suggest that LiDAR-based techniques for quantifying the 3D light environment of small shrubs exposed to low solar angles reveal patterns of photosynthetic partitioning that may otherwise be overlooked using more traditional techniques. © 2016 Elsevier B.V."
"35300998400;8880094700;23393212200;57218183583;36553486200;","Large-scale ocean circulation-cloud interactions reduce the pace of transient climate change",2016,"10.1002/2016GL067931","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84968725152&doi=10.1002%2f2016GL067931&partnerID=40&md5=bdaf333c1641127e99dcda0ab445c2a5","Changes to the large-scale oceanic circulation are thought to slow the pace of transient climate change due, in part, to their influence on radiative feedbacks. Here we evaluate the interactions between CO2-forced perturbations to the large-scale ocean circulation and the radiative cloud feedback in a climate model. Both the change of the ocean circulation and the radiative cloud feedback strongly influence the magnitude and spatial pattern of surface and ocean warming. Changes in the ocean circulation reduce the amount of transient global warming caused by the radiative cloud feedback by helping to maintain low cloud coverage in the face of global warming. The radiative cloud feedback is key in affecting atmospheric meridional heat transport changes and is the dominant radiative feedback mechanism that responds to ocean circulation change. Uncertainty in the simulated ocean circulation changes due to CO2 forcing may contribute a large share of the spread in the radiative cloud feedback among climate models. ©2016. American Geophysical Union. All Rights Reserved."
"7401793588;12645612500;57208765879;","Uncertainties in cloud phase and optical thickness retrievals from the Earth Polychromatic Imaging Camera (EPIC)",2016,"10.5194/amt-9-1785-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966706280&doi=10.5194%2famt-9-1785-2016&partnerID=40&md5=36ba757abe9b2d71f1741780e0b05bf2","This paper presents an investigation of the expected uncertainties of a single-channel cloud optical thickness (COT) retrieval technique, as well as a simple cloud-temperature-threshold-based thermodynamic phase approach, in support of the Deep Space Climate Observatory (DSCOVR) mission. DSCOVR cloud products will be derived from Earth Polychromatic Imaging Camera (EPIC) observations in the ultraviolet and visible spectra. Since EPIC is not equipped with a spectral channel in the shortwave or mid-wave infrared that is sensitive to cloud effective radius (CER), COT will be inferred from a single visible channel with the assumption of appropriate CER values for liquid and ice phase clouds. One month of Aqua MODerate-resolution Imaging Spectroradiometer (MODIS) daytime granules from April 2005 is selected for investigating cloud phase sensitivity, and a subset of these granules that has similar EPIC Sun-view geometry is selected for investigating COT uncertainties. EPIC COT retrievals are simulated with the same algorithm as the operational MODIS cloud products (MOD06), except using fixed phase-dependent CER values. Uncertainty estimates are derived by comparing the single-channel COT retrievals with the baseline bi-spectral MODIS retrievals. Results show that a single-channel COT retrieval is feasible for EPIC. For ice clouds, single-channel retrieval errors are minimal (< 2 %) due to the particle size insensitivity of the assumed ice crystal (i.e., severely roughened aggregate of hexagonal columns) scattering properties at visible wavelengths, while for liquid clouds the error is mostly limited to within 10 %, although for thin clouds (COT < 2) the error can be higher. Potential uncertainties in EPIC cloud masking and cloud temperature retrievals are not considered in this study. © Author(s) 2016."
"57188665106;55889593300;24172039900;7003627515;55634326100;","Improved GRACE regional mass balance estimates of the Greenland ice sheet cross-validated with the input-output method",2016,"10.5194/tc-10-895-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84967201473&doi=10.5194%2ftc-10-895-2016&partnerID=40&md5=a6bd3ebe7959b073f4b8cc498d87da21","In this study, we use satellite gravimetry data from the Gravity Recovery and Climate Experiment (GRACE) to estimate regional mass change of the Greenland ice sheet (GrIS) and neighboring glaciated regions using a least squares inversion approach. We also consider results from the input-output method (IOM). The IOM quantifies the difference between the mass input and output of the GrIS by studying the surface mass balance (SMB) and the ice discharge (D). We use the Regional Atmospheric Climate Model version 2.3 (RACMO2.3) to model the SMB and derive the ice discharge from 12 years of high-precision ice velocity and thickness surveys. We use a simulation model to quantify and correct for GRACE approximation errors in mass change between different subregions of the GrIS, and investigate the reliability of pre-1990s ice discharge estimates, which are based on the modeled runoff. We find that the difference between the IOM and our improved GRACE mass change estimates is reduced in terms of the long-term mass change when using a reference discharge derived from runoff estimates in several subareas. In most regions our GRACE and IOM solutions are consistent with other studies, but differences remain in the northwestern GrIS. We validate the GRACE mass balance in that region by considering several different GIA models and mass change estimates derived from data obtained by the Ice, Cloud and land Elevation Satellite (ICESat). We conclude that the approximated mass balance between GRACE and IOM is consistent in most GrIS regions. The difference in the northwest is likely due to underestimated uncertainties in the IOM solutions. © Author(s) 2016."
"56754594800;6602002452;55598938800;6603701937;55837993200;7004499037;8786620100;57204744052;7501601923;15821672300;7202636533;7003501766;","Inverse modeling of GOSAT-retrieved ratios of total column CH4 and CO2 for 2009 and 2010",2016,"10.5194/acp-16-5043-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966453566&doi=10.5194%2facp-16-5043-2016&partnerID=40&md5=dd04090f69f818abb41dbc1532449054","This study investigates the constraint provided by greenhouse gas measurements from space on surface fluxes. Imperfect knowledge of the light path through the atmosphere, arising from scattering by clouds and aerosols, can create biases in column measurements retrieved from space. To minimize the impact of such biases, ratios of total column retrieved CH4 and CO2 (Xratio) have been used. We apply the ratio inversion method described in Pandey et al. (2015) to retrievals from the Greenhouse Gases Observing SATellite (GOSAT). The ratio inversion method uses the measured Xratio as a weak constraint on CO2 fluxes. In contrast, the more common approach of inverting proxy CH4 retrievals (Frankenberg et al., 2005) prescribes atmospheric CO2 fields and optimizes only CH4 fluxes. The TM5-4DVAR (Tracer Transport Model version 5-variational data assimilation system) inverse modeling system is used to simultaneously optimize the fluxes of CH4 and CO2 for 2009 and 2010. The results are compared to proxy inversions using model-derived CO2 mixing ratios (XCO2model) from CarbonTracker and the Monitoring Atmospheric Composition and Climate (MACC) Reanalysis CO2 product. The performance of the inverse models is evaluated using measurements from three aircraft measurement projects. Xratio and XCO2model are compared with TCCON retrievals to quantify the relative importance of errors in these components of the proxy XCH4 retrieval (XCH4proxy). We find that the retrieval errors in Xratio (mean Combining double low line 0.61%) are generally larger than the errors in XCO2model (mean Combining double low line 0.24 and 0.01% for CarbonTracker and MACC, respectively). On the annual timescale, the CH4 fluxes from the different satellite inversions are generally in agreement with each other, suggesting that errors in XCO2model do not limit the overall accuracy of the CH4 flux estimates. On the seasonal timescale, however, larger differences are found due to uncertainties in XCO2model, particularly over Australia and in the tropics. The ratio method stays closer to the a priori CH4 flux in these regions, because it is capable of simultaneously adjusting the CO2 fluxes. Over tropical South America, comparison to independent measurements shows that CO2 fields derived from the ratio method are less realistic than those used in the proxy method. However, the CH4 fluxes are more realistic, because the impact of unaccounted systematic uncertainties is more evenly distributed between CO2 and CH4. The ratio inversion estimates an enhanced CO2 release from tropical South America during the dry season of 2010, which is in accordance with the findings of Gatti et al. (2014) and Van der Laan et al. (2015). The performance of the ratio method is encouraging, because despite the added nonlinearity due to the assimilation of Xratio and the significant increase in the degree of freedom by optimizing CO2 fluxes, still consistent results are obtained with respect to other CH4 inversions. © Author(s) 2016."
"7202746634;7003351429;6603343811;24734166800;56109365900;24173372900;8345342800;36465214000;35777722800;56109159100;55340010500;57205842560;6603501832;57189092691;57189098128;57189099063;12645700600;55196799200;54882457200;17341189400;23670554500;34771961300;36495529100;57189089615;6603321633;56185117700;55752464600;35413839400;22951373900;55846756000;55914757700;57189098431;6504341178;","LOAC: A small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles-Part 1: Principle of measurements and instrument evaluation",2016,"10.5194/amt-9-1721-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84965112358&doi=10.5194%2famt-9-1721-2016&partnerID=40&md5=e269f7ca137422c8623a875090477c90","The study of aerosols in the troposphere and in the stratosphere is of major importance both for climate and air quality studies. Among the numerous instruments available, optical aerosol particles counters (OPCs) provide the size distribution in diameter range from about 100 nm to a few tens of μm. Most of them are very sensitive to the nature of aerosols, and this can result in significant biases in the retrieved size distribution. We describe here a new versatile optical particle/sizer counter named LOAC (Light Optical Aerosol Counter), which is light and compact enough to perform measurements not only at the surface but under all kinds of balloons in the troposphere and in the stratosphere. LOAC is an original OPC performing observations at two scattering angles. The first one is around 12-, and is almost insensitive to the refractive index of the particles; the second one is around 60± and is strongly sensitive to the refractive index of the particles. By combining measurement at the two angles, it is possible to retrieve the size distribution between 0.2 and 100 μm and to estimate the nature of the dominant particles (droplets, carbonaceous, salts and mineral particles) when the aerosol is relatively homogeneous. This typology is based on calibration charts obtained in the laboratory. The uncertainty for total concentrations measurements is ±20% when concentrations are higher than 1 particle cm-3 (for a 10 min integration time). For lower concentrations, the uncertainty is up to about ±60% for concentrations smaller than 10-2 particle cm-3. Also, the uncertainties in size calibration are ±0.025 μm for particles smaller than 0.6 μm, 5% for particles in the 0.7-2 μm range, and 10% for particles greater than 2 μm. The measurement accuracy of submicronic particles could be reduced in a strongly turbid case when concentration of particles &gt; 3 μm exceeds a few particles cm-3. Several campaigns of cross-comparison of LOAC with other particle counting instruments and remote sensing photometers have been conducted to validate both the size distribution derived by LOAC and the retrieved particle number density. The typology of the aerosols has been validated in well-defined conditions including urban pollution, desert dust episodes, sea spray, fog, and cloud. Comparison with reference aerosol mass monitoring instruments also shows that the LOAC measurements can be successfully converted to mass concentrations. © Author(s) 2016. CC Attribution 3.0 License."
"35203939400;22633429500;57189051559;55807774100;36887737900;6701806265;","3-D water vapor field in the atmospheric boundary layer observed with scanning differential absorption lidar",2016,"10.5194/amt-9-1701-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964931494&doi=10.5194%2famt-9-1701-2016&partnerID=40&md5=c64e5ed730a63eccc800164157cf56b6","High-resolution three-dimensional (3-D) water vapor data of the atmospheric boundary layer (ABL) are required to improve our understanding of land-atmosphere exchange processes. For this purpose, the scanning differential absorption lidar (DIAL) of the University of Hohenheim (UHOH) was developed as well as new analysis tools and visualization methods. The instrument determines 3-D fields of the atmospheric water vapor number density with a temporal resolution of a few seconds and a spatial resolution of up to a few tens of meters. We present three case studies from two field campaigns. In spring 2013, the UHOH DIAL was operated within the scope of the HD(CP)2 Observational Prototype Experiment (HOPE) in western Germany. HD(CP)2 stands for High Definition of Clouds and Precipitation for advancing Climate Prediction and is a German research initiative. Range-height indicator (RHI) scans of the UHOH DIAL show the water vapor heterogeneity within a range of a few kilometers up to an altitude of 2 km and its impact on the formation of clouds at the top of the ABL. The uncertainty of the measured data was assessed for the first time by extending a technique to scanning data, which was formerly applied to vertical time series. Typically, the accuracy of the DIAL measurements is between 0.5 and 0.8 g m-3 (or &lt; 6 %) within the ABL even during daytime. This allows for performing a RHI scan from the surface to an elevation angle of 90° within 10 min. In summer 2014, the UHOH DIAL participated in the Surface Atmosphere Boundary Layer Exchange (SABLE) campaign in southwestern Germany. Conical volume scans were made which reveal multiple water vapor layers in three dimensions. Differences in their heights in different directions can be attributed to different surface elevation. With low-elevation scans in the surface layer, the humidity profiles and gradients can be related to different land cover such as maize, grassland, and forest as well as different surface layer stabilities. © Author(s) 2016."
"55669646100;57202301596;6506392172;56003800800;24076333900;","Detecting cross-equatorial wind change as a fingerprint of climate response to anthropogenic aerosol forcing",2016,"10.1002/2016GL068521","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979492214&doi=10.1002%2f2016GL068521&partnerID=40&md5=a2d25bffbf43031bef432bd38116dc6e","Anthropogenic aerosols are a major driver of the twetieth century climate change. In climate models, the aerosol forcing, larger in the Northern than Southern Hemispheres, induces an interhemispheric Hadley circulation. In support of the model result, we detected a robust change in the zonal mean cross-equatorial wind over the past 60 years from ship observations and reanalyses, accompanied by physically consistent changes in atmospheric pressure and marine cloud cover. Single-forcing experiments indicate that the observed change in cross-equatorial wind is a fingerprint of aerosol forcing. This zonal mean mode follows the evolution of global aerosol forcing that is distinct from regional changes in the Atlantic sector. Atmospheric simulations successfully reproduce this interhemispheric mode, indicating the importance of sea surface temperature mediation in response to anthropogenic aerosol forcing. As societies awaken to reduce aerosol emissions, a phase reversal of this interhemispheric mode is expected in the 21st century. © 2016. American Geophysical Union. All Rights Reserved."
"55995261600;35849722200;41362078500;14326501100;56649594800;55567649200;56939103900;","A closure study of aerosol optical properties at a regional background mountainous site in Eastern China",2016,"10.1016/j.scitotenv.2016.01.205","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956628194&doi=10.1016%2fj.scitotenv.2016.01.205&partnerID=40&md5=d26efbf726eecaa4e5930adb8245d7b8","There is a large uncertainty in evaluating the radiative forcing from aerosol-radiation and aerosol-cloud interactions due to the limited knowledge on aerosol properties. In-situ measurements of aerosol physical and chemical properties were carried out in 2012 at Mt. Huang (the Yellow Mountain), a continental background mountainous site in eastern China. An aerosol optical closure study was performed to verify the model outputs by using the measured aerosol optical properties, in which a spherical Mie model with assumptions of external and core-shell mixtures on the basis of a two-component optical aerosol model and high size-segregated element carbon (EC) ratio was applied. Although the spherical Mie model would underestimate the real scattering with increasing particle diameters, excellent agreement between the calculated and measured values was achieved with correlation coefficients above 0.98. Sensitivity experiments showed that the EC ratio had a negligible effect on the calculated scattering coefficient, but largely influenced the calculated absorption coefficient. The high size-segregated EC ratio averaged over the study period in the closure was enough to reconstruct the aerosol absorption coefficient in the Mie model, indicating EC size resolution was more important than time resolution in retrieving the absorption coefficient in the model. The uncertainties of calculated scattering and absorption coefficients due to the uncertainties of measurements and model assumptions yielded by a Monte Carlo simulation were ±. 6% and ±. 14% for external mixture and ±. 9% and ±. 31% for core-shell mixture, respectively. This study provided an insight into the inherent relationship between aerosol optical properties and physicochemical characteristics in eastern China, which could supplement the database of aerosol optical properties for background sites in eastern China and provide a method for regions with similar climate. © 2016 Elsevier B.V."
"6507237454;14018040300;15844796800;7201659232;","Controls on interannual variability in lightning-caused fire activity in the western US",2016,"10.1088/1748-9326/11/4/045005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964595315&doi=10.1088%2f1748-9326%2f11%2f4%2f045005&partnerID=40&md5=1c32f644316c84d678a1f72d78fc6acf","Lightning-caused wildfires account for a majority of burned area across the western United States (US), yet lightning remains among the more unpredictable spatiotemporal aspects of the fire environment and a challenge for both modeling and managing fire activity. A data synthesis of cloud-to-ground lightning strikes, climate and fire data across the western US from 1992 to 2013 was conducted to better understand geographic variability in lightning-caused wildfire and the factors that influence interannual variability in lightning-caused wildfire at regional scales. Distinct geographic variability occurred in the proportion of fires and area burned attributed to lightning, with a majority of fires in the interior western US attributed to lightning. Lightning ignition efficiency was highest across the western portion of the region due to the concomitance of peak lightning frequency and annual nadir in fuel moisture in mid-to-late summer. For most regions the number of total and dry lightning strikes exhibited strong interannual correlation with the number of lightning-caused fires, yet were a poor predictor of area burned at regional scales. Commonality in climate-fire relationships for regional annual area burned by lightning- versus human-ignited fires suggests climate conditions, rather than lightning activity, are the predominant control of interannual variability in area burned by lightning-caused fire across much of the western US. © 2016 IOP Publishing Ltd."
"56011266900;37012909900;7004462227;57189224638;7003577666;7102409836;57189213174;56384666800;","Molecular transformations of phenolic SOA during photochemical aging in the aqueous phase: Competition among oligomerization, functionalization, and fragmentation",2016,"10.5194/acp-16-4511-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966318827&doi=10.5194%2facp-16-4511-2016&partnerID=40&md5=6ffc83f9b76b8f502ba6df9ae81a25db","Organic aerosol is formed and transformed in atmospheric aqueous phases (e.g., cloud and fog droplets and deliquesced airborne particles containing small amounts of water) through a multitude of chemical reactions. Understanding these reactions is important for a predictive understanding of atmospheric aging of aerosols and their impacts on climate, air quality, and human health. In this study, we investigate the chemical evolution of aqueous secondary organic aerosol (aqSOA) formed during reactions of phenolic compounds with two oxidants - the triplet excited state of an aromatic carbonyl (3Cĝ-) and hydroxyl radical (<mo>ĝ€¢</mo>OH). Changes in the molecular composition of aqSOA as a function of aging time are characterized using an offline nanospray desorption electrospray ionization mass spectrometer (nano-DESI MS) whereas the real-time evolution of SOA mass, elemental ratios, and average carbon oxidation state (OSC) are monitored using an online aerosol mass spectrometer (AMS). Our results indicate that oligomerization is an important aqueous reaction pathway for phenols, especially during the initial stage of photooxidation equivalent to ĝ1/4 ĝ€2ĝ€h irradiation under midday winter solstice sunlight in Northern California. At later reaction times functionalization (i.e., adding polar oxygenated functional groups to the molecule) and fragmentation (i.e., breaking of covalent bonds) become more important processes, forming a large variety of functionalized aromatic and open-ring products with higher OSC values. Fragmentation reactions eventually dominate the photochemical evolution of phenolic aqSOA, forming a large number of highly oxygenated ring-opening molecules with carbon numbers (<i>n</i>C) below 6. The average <i>n</i>C of phenolic aqSOA decreases while average OSC increases over the course of photochemical aging. In addition, the saturation vapor pressures (<i>C</i>ĝ-) of dozens of the most abundant phenolic aqSOA molecules are estimated. A wide range of <i>C</i>ĝ- values is observed, varying from &lt;ĝ€10ĝ'20ĝ€μgĝ€mĝ'3 for functionalized phenolic oligomers to &gt;ĝ€10ĝ€μgĝ€mĝ'3 for small open-ring species. The detection of abundant extremely low-volatile organic compounds (ELVOC) indicates that aqueous reactions of phenolic compounds are likely an important source of ELVOC in the atmosphere."
"37089417300;7102988363;7004194999;","The global impact of the transport sectors on atmospheric aerosol in 2030 - Part 2: Aviation",2016,"10.5194/acp-16-4481-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964550163&doi=10.5194%2facp-16-4481-2016&partnerID=40&md5=4ffaf563b06c105c9d820b6ededffeb2","We use the EMAC (ECHAM/MESSy Atmospheric Chemistry) global climate-chemistry model coupled to the aerosol module MADE (Modal Aerosol Dynamics model for Europe, adapted for global applications) to simulate the impact of aviation emissions on global atmospheric aerosol and climate in 2030. Emissions of short-lived gas and aerosol species follow the four Representative Concentration Pathways (RCPs) designed in support of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. We compare our findings with the results of a previous study with the same model configuration focusing on year 2000 emissions. We also characterize the aviation results in the context of the other transport sectors presented in a companion paper. In spite of a relevant increase in aviation traffic volume and resulting emissions of aerosol (black carbon) and aerosol precursor species (nitrogen oxides and sulfur dioxide), the aviation effect on particle mass concentration in 2030 remains quite negligible (on the order of a few ngm-3), about 1 order of magnitude less than the increase in concentration due to other emission sources. Due to the relatively small size of the aviation-induced aerosol, however, the increase in particle number concentration is significant in all scenarios (about 1000cm-3), mostly affecting the northern mid-latitudes at typical flight altitudes (7-12km). This largely contributes to the overall change in particle number concentration between 2000 and 2030, which also results in significant climate effects due to aerosol-cloud interactions. Aviation is the only transport sector for which a larger impact on the Earth's radiation budget is simulated in the future: the aviation-induced radiative forcing in 2030 is more than doubled with respect to the year 2000 value of -15mWm-2 in all scenarios, with a maximum value of -63mWm-2 simulated for RCP2.6. © Author(s) 2016."
"56276584900;10042470700;35301550500;7004807312;","Why must a solar forcing be larger than a CO2 forcing to cause the same global mean surface temperature change?",2016,"10.1088/1748-9326/11/4/044013","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964786427&doi=10.1088%2f1748-9326%2f11%2f4%2f044013&partnerID=40&md5=7cbd1210c6ed25add803e03806eeff62","Many previous studies have shown that a solar forcing must be greater than a CO2 forcing to cause the same global mean surface temperature change but a process-based mechanistic explanation is lacking in the literature. In this study, we investigate the physical mechanisms responsible for the lower efficacy of solar forcing compared to an equivalent CO2 forcing. Radiative forcing is estimated using the Gregory method that regresses top-of-atmosphere (TOA) radiative flux against the change in global mean surface temperature. For a 2.25% increase in solar irradiance that produces the same long term global mean warming as a doubling of CO2 concentration, we estimate that the efficacy of solar forcing is ∼80% relative to CO2 forcing in the NCAR CAM5 climate model. We find that the fast tropospheric cloud adjustments especially over land and stratospheric warming in the first four months cause the slope of the regression between the TOA net radiative fluxes and surface temperature to be steeper in the solar forcing case. This steeper slope indicates a stronger net negative feedback and hence correspondingly a larger solar forcing than CO2 forcing for the same equilibrium surface warming. Evidence is provided that rapid land surface warming in the first four months sets up a land-sea contrast that markedly affects radiative forcing and the climate feedback parameter over this period. We also confirm the robustness of our results using simulations from the Hadley Centre climate model. Our study has important implications for estimating the magnitude of climate change caused by volcanic eruptions, solar geoengineering and past climate changes caused by change in solar irradiance such as Maunder minimum. © 2016 IOP Publishing Ltd."
"57188653495;9736750200;55911591000;","Light pollution: Assessment of sky glow on two dark sky regions of Portugal",2016,"10.1080/15287394.2016.1153446","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962046008&doi=10.1080%2f15287394.2016.1153446&partnerID=40&md5=6fce9dfdc0774a0207a656202e21d010","Artificial light at night (ALAN), producing light pollution (LP), is not a matter restricted to astronomy anymore. Light is part of modern societies and, as a consequence, the natural cycle day–night (bright–dark) has been interrupted in a large segment of the global population. There is increasing evidence that exposure to certain types of light at night and beyond threshold levels may produce hazardous effects to humans and the environment. The concept of “dark skies reserves” is a step forward in order to preserve the night sky and a means of enhancing public awareness of the problem of spread of light pollution worldwide. The aim of this study was to assess the skyglow at two sites in Portugal, the Peneda-Gerês National Park (PNPG) and the region now known as Dark Sky Alqueva Reserve. The latter site was classified as a “Starlight Tourism Destination“ by the Starlight Foundation (the first in the world to achieve this classification) following a series of night sky measurements in situ described herein. The measurements at PNPG also contributed to the new set of regulations concerning light pollution at this national park. This study presents the first in situ systematic measurements of night sky brightness, showing that at the two sites the skies are mostly in levels 3 to 4 of the Bortle 9-level scale (with level 1 being the best achievable). The results indicate that the sources of light pollution and skyglow can be attributed predominantly to contamination from nearby urban regions. © 2016 Taylor & Francis."
"7403625607;7403180902;","An initial study on climate change fingerprinting using the reflected solar spectra",2016,"10.1175/JCLI-D-15-0297.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964856458&doi=10.1175%2fJCLI-D-15-0297.1&partnerID=40&md5=073693e74f731576aa6fb721d6266477","Attribution of averaged spectral variation over large spatial and temporal scales to different climate variables is central to climate change fingerprinting. Using 10 years of satellite data for simulation, the authors generate a group of observation-based spectral fingerprints and a time series of monthly mean reflectance spectra over the ocean in five large latitude regions and globally. Next, these fingerprints and the interannual variation spectra are used to retrieve the interannual changes in the relevant climate variables to test the concept of using the spectral fingerprinting approach for climate change attribution. Comparing the fingerprinting retrieval of climate variable change to the actual underlying variable change, the RMS differences between the two are less than twice as large as the monthly variability for all variables in all regions. Instances where larger errors are observed correspond to those variables with large nonlinear radiative response, such as the cloud optical depth and the ice particle size. Using the linear fingerprinting approach and accounting for the nonlinear radiative error in fingerprints results in significantly higher retrieval accuracy; the RMS errors are reduced to less than the monthly variability for nearly all variables, indicating the profound impact of the nonlinear error on fingerprinting retrieval. Another important finding is that if the cloud fraction is known a priori, the retrieval accuracy in cloud optical depth would be improved substantially. Moreover, a better retrieval for the water vapor amount and aerosol optical depth can be achieved from the clear-sky data only. The test results demonstrate that climate change fingerprinting based on reflected solar benchmark spectra is possible. © 2016 American Meteorological Society."
"55418728800;7202145115;","The role of cloud radiative heating in determining the location of the ITCZ in aquaplanet simulations",2016,"10.1175/JCLI-D-15-0521.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964804762&doi=10.1175%2fJCLI-D-15-0521.1&partnerID=40&md5=874d3bde4d6a573f8e15c011aae4d8b7","The relationship between the tropical circulation and cloud radiative effect is investigated. Output from the Clouds On-Off Klimate Intercomparison Experiment (COOKIE) is used to examine the impact of cloud radiative effects on circulation and climate. In aquaplanet simulations with a fixed SST pattern, the cloud radiative effect leads to an equatorward contraction of the intertropical convergence zone (ITCZ) and a reduction of the double ITCZ problem. It is shown that the cloud radiative heating in the upper troposphere increases the temperature, weakens CAPE, and inhibits the onset of convection until it is closer to the equator, where SSTs are higher. Precipitation peaks at higher values in a narrower band when the cloud radiative effects are active, compared to when they are inactive, owing to the enhancement in moisture convergence. Additionally, cloud-radiation interactions strengthen the mean meridional circulation and consequently enhance the moisture convergence. Although the mean tropical precipitation decreases, the atmospheric cloud radiative effect has a strong meridional gradient, which supports stronger poleward energy flux and speeds up the Hadley circulation. Cloud radiative heating also enhances cloud water path (liquid plus ice), which, combined with the reduction in precipitation, suggests that the cloud radiative heating reduces precipitation efficiency in these models. © 2016 American Meteorological Society."
[No author id available],"Study shows brightening effect of volcanic sulfur on cloudsis real",2016,"10.1175/BAMS_974_517-522_NOWCAST","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85048311905&doi=10.1175%2fBAMS_974_517-522_NOWCAST&partnerID=40&md5=e91c1dd5370aef8ce1fb8811184c7461","Dennis Hartmann of the University of Washington published a study in a Geophysical Research Letters paper, which confirmed a belief that the emission of sulfur into the atmosphere leads to brighter clouds. The study could give scientists the chance to nail down one of the big uncertainties in climate models. The researchers studied moderate-resolution imaging spec­troradiometer (MODIS) data on water droplet size in the marine cloud layer adjacent to the con­tinuous sulfur gas leak. When sulfuric acid particles are present in the atmosphere, water vapor condenses around them, creating many smaller-than-usual droplets that form brighter clouds, which in turn reflect more sunlight than normal clouds. More specifically, the researchers made an intriguing finding for the years 1998-2012 in which the see­saw index indicated higher sea levels in the western Pacific than in the eastern Pacific."
"6506674287;7003341111;12804290300;7006208606;36056590400;55123983400;6506743283;56209544000;7003303148;","FluxEngine: A flexible processing system for calculating atmosphere-ocean carbon dioxide gas fluxes and climatologies",2016,"10.1175/JTECH-D-14-00204.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964998624&doi=10.1175%2fJTECH-D-14-00204.1&partnerID=40&md5=bbb0fa99fab2c52a6f62ea9923490584","The air-sea flux of greenhouse gases [e.g., carbon dioxide (CO2)] is a critical part of the climate system and a major factor in the biogeochemical development of the oceans. More accurate and higher-resolution calculations of these gas fluxes are required if researchers are to fully understand and predict future climate. Satellite Earth observation is able to provide large spatial-scale datasets that can be used to study gas fluxes. However, the large storage requirements needed to host such data can restrict its use by the scientific community. Fortunately, the development of cloud computing can provide a solution. This paper describes an open-source air-sea CO2 flux processing toolbox called the ""FluxEngine,"" designed for use on a cloud-computing infrastructure. The toolbox allows users to easily generate global and regional air-sea CO2 flux data from model, in situ, and Earth observation data, and its air-sea gas flux calculation is user configurable. Its current installation on the Nephalae Cloud allows users to easily exploit more than 8 TB of climate-quality Earth observation data for the derivation of gas fluxes. The resultant netCDF data output files contain &gt; 20 data layers containing the various stages of the flux calculation along with process indicator layers to aid interpretation of the data. This paper describes the toolbox design, which verifies the air-sea CO2 flux calculations; demonstrates the use of the tools for studying global and shelf sea air-sea fluxes; and describes future developments. © 2016 American Meteorological Society."
"13006055400;7102425008;","Regime dependence of cloud condensate variability observed at the Atmospheric Radiation Measurement Sites",2016,"10.1002/qj.2783","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966692642&doi=10.1002%2fqj.2783&partnerID=40&md5=fa2b848252422c4ea1083238d0dc1c89","Microphysical processes and cloud-radiation interaction occur on spatial scales of variability smaller than those represented explicitly in global weather forecasting and climate models. It is therefore necessary to parametrize the unresolved heterogeneity of humidity and cloud condensate in order to predict process rates accurately. Ground-based observations from the Atmospheric Radiation Measurement sites located in various climatic regions of the world provide a source of high-temporal-resolution observations of cloud condensate. A number of different retrieval products for cloud condensate are assessed for the different geographical regions, years and seasons. The retrieval reliability varies with cloud type, but for cloud categories largely unaffected by precipitation a comparison across sites and longer time periods is possible. These observations confirm previously documented variability behaviour as a function of cloud fraction, but also reveal a systematic regime dependence that is not captured by existing parametrizations. Condensate variability measured as a fractional standard deviation (FSD) in warm boundary-layer clouds is greater in the Tropics than in mid and high latitudes for scenes with comparable cloud type and fraction, with the observed FSD varying from 1.2 in the Tropics to 0.4 in the Arctic. A parametrization of the FSD of cloud liquid condensate based on the grid-box mean total water amount and cloud fraction is formulated and shown to capture the observed range of FSD values better across different geographical sites and different seasons. The regime dependence of FSD for cirrus cloud is less pronounced than that for liquid clouds and is found largely to agree with FSD values previously derived from satellite observations. Time-height sections of cloud water content retrieved from ground-based observations on two days in June 2010 on the island of Graciosa in the Azores. The two panels show days with (top) cumulus and (bottom) stratocumulus clouds, illustrating how condensate variability can differ between cloud regimes. This variability of cloud water impacts, for example, the rate at which the cloud produces drizzle and the way in which radiation interacts with the cloud. Therefore, the cloud water variability needs to be well represented in models. © 2016 Royal Meteorological Society."
"36018467800;9248887100;8696069500;57201945714;7003823107;","On the potential for abrupt Arctic winter sea ice loss",2016,"10.1175/JCLI-D-15-0466.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013696787&doi=10.1175%2fJCLI-D-15-0466.1&partnerID=40&md5=d6a2bd9d2369534082335f696dd009b3","The authors examine the transition from a seasonally ice-covered Arctic to an Arctic Ocean that is sea ice free all year round under increasing atmospheric CO2 levels. It is shown that in comprehensive climate models, such loss of Arctic winter sea ice area is faster than the preceding loss of summer sea ice area for the same rate of warming. In two of the models, several million square kilometers of winter sea ice are lost within only one decade. It is shown that neither surface albedo nor cloud feedbacks can explain the rapid winter ice loss in the climate model MPI-ESM by suppressing both feedbacks in the model. The authors argue that the large sensitivity of winter sea ice area in the models is caused by the asymmetry between melting and freezing: an ice-free summer requires the complete melt of even the thickest sea ice, which is why the perennial ice coverage decreases only gradually as more and more of the thinner ice melts away. In winter, however, sea ice areal coverage remains high as long as sea ice still forms, and then drops to zero wherever the ocean warms sufficiently to no longer form ice during winter. The loss of basinwide Arctic winter sea ice area, however, is still gradual in most models since the threshold mechanism proposed here is reversible and not associated with the existence of multiple steady states. As this occurs in every model analyzed here and is independent of any specific parameterization, it is likely to be relevant in the real world. © 2016 American Meteorological Society."
"15050523700;15047538100;10045312900;","Evaluation of cloud properties in the NCEP CFSv2 model and its linkage with Indian summer monsoon",2016,"10.1007/s00704-015-1404-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84923013542&doi=10.1007%2fs00704-015-1404-3&partnerID=40&md5=373fd946283a8408a5c976676e869d21","Cloud fraction, which varies greatly among general circulation models, plays a crucial role in simulation of Indian summer monsoon rainfall (ISMR). The NCEP Climate Forecast System version 2 (CFSv2) model is evaluated in terms of its simulation of cloud fraction, cloud condensate, outgoing longwave radiation (OLR), and tropospheric temperature (TT). Biases in these simulated quantities are computed using observations from CALIPSO and reanalysis data from MERRA. It is shown that CFSv2 underestimates (overestimates) high- (mid-) level clouds. The cloud condensate is also examined to see its impact on different types of clouds. The upper-level cloud condensate is underestimated, particularly during the summer monsoon period, which leads to a cold TT and a dry precipitation bias. The unrealistically weak TT gradient between ocean and land is responsible for the underestimation of ISMR. The model-simulated OLR is overestimated which depicts the weaker convective activity. A large underestimate of precipitable water is also seen along the cross-equatorial flow and particularly over the Indian land region collocated with a dry precipitation bias. The linkages among cloud microphysical, thermodynamical, and dynamical processes are identified here. Thus, this study highlights the importance of cloud properties, a major cause of uncertainty in CFSv2, and also proposes a pathway for improvements in its simulation of the Indian summer monsoon. © 2015, Springer-Verlag Wien."
"7007088807;23988450000;","Simple solar radiation modelling for different cloud types and climatologies",2016,"10.1007/s00704-015-1400-7","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84923253990&doi=10.1007%2fs00704-015-1400-7&partnerID=40&md5=1cda7287dc6c3065241147eca32e88dd","The instantaneous Cloud Fraction Coverage (iCFC) and Cloud Type (iCTY) products of the Climate Monitoring Satellite Application Facility are used to develop simple relationships between solar global irradiance and cloud amount and types. Radiometric measurements from five Romanian weather stations are used. Solar radiation relationships are proposed for clear sky, overcast sky and cloudy sky. A procedure to average the iCTY data is proposed, and eight classes of averaged iCTY values are considered. Two procedures are used to define the overcast sky and two cloudy sky solar radiation models are considered. Overcast skies consisting of stratiform clouds (CTY classes 8 to 14) are the most challenging when solar radiation modelling is considered. The overcast sky models have lower accuracy at high irradiance values. The best cloudy sky model has relative root mean square error values ranging between 17.6 % (for CTY classes 1 to 4) and 67.6 % (for CTY classes 12 to 14). For most CTY classes, the model performs worse at intermediate irradiance values. © 2015, Springer-Verlag Wien."
"56972687700;36551761100;55664151400;7401672948;57207482495;34768438000;56973424600;","Developing daily cloud-free snow composite products from MODIS terra-aqua and IMS for the tibetan plateau",2016,"10.1109/TGRS.2015.2496950","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84947975954&doi=10.1109%2fTGRS.2015.2496950&partnerID=40&md5=7fe07c28dc7c98cb2d59d23d6483bd80","Daily snow cover mapping is difficult when Moderate Resolution Imaging Spectroradiometer (MODIS) snow cover products are cloud obscured. The daily cloud-free snow cover product provides an essential parameter for hydrological modeling, climate system studies, and snow-caused disaster monitoring on the Tibetan Plateau (TP). In this paper, we present an algorithm, Terra-Aqua-IMS (TAI), which combines MODIS Terra and Aqua (500 m) and the Interactive Multisensor Snow and Ice Mapping System (IMS; 4 km) to produce a daily cloud-free snow cover product (500 m). The overall accuracy of the new TAI over the TP is 94% as compared with ground stations in all-sky conditions; this value is significantly higher than the 64% of the blended MODIS Terra-Aqua product and the 55% and 50% of the original MODIS Terra and Aqua products, respectively. Without the IMS, the daily combination of MODIS Terra-Aqua can only remove limited cloud contamination: 37.3% of the annual mean cloud coverage compared with 46.6% (MODIS Terra) and 55.1% (MODIS Aqua). The resulting annual mean snow cover over the TP from the daily TAI data is 19.1%, which is much larger than the 4.7%-8.1% from the daily original MODIS Terra/Aqua and the blended Terra-Aqua snow product due to cloud blockage. © 1980-2012 IEEE."
"6504005508;57197432263;6602519468;","Laboratory measurements of sedimentation velocity of columnar ice crystals",2016,"10.1002/qj.2766","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963594873&doi=10.1002%2fqj.2766&partnerID=40&md5=afba70dd565ba88ea39cce704ec5217a","The terminal velocity of cloud particles may be particularly important to climate studies, because they may have a non-negligible effect on the radiation budget of the planet, and on the lifetime of clouds. In the present study, the terminal velocity of individual columnar ice crystals was measured under controlled laboratory conditions. The size and fall orientation were determined for ice crystals with maximum dimensions less than 160 μm. The results, which are in agreement with the fall velocity presented in previous studies, show a random orientation of the columnar ice crystals during free fall with a fall velocity which is best represented by their capacitance. A linear relationship between fall velocity and ice crystal capacitance is presented that could be used in cloud modelling. Although the mass of ice crystals was not measured, an estimation of this parameter was made and an empirical Best-Reynolds power-law relationship was found. © 2016 Royal Meteorological Society."
"8911960700;56562495600;7202566804;56563144800;","Search for an astronomical site in Kenya (SASKYA) using climate reanalyses and high-resolution meteorological model data",2016,"10.1007/s00704-014-1366-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84925263746&doi=10.1007%2fs00704-014-1366-x&partnerID=40&md5=1e642b78fe70ad4979621725a5caed0a","The goal of the Search for an Astronomical Site in Kenya (SASKYA) project is to identify the best possible site(s) in Kenya for astronomical optical observation, using ERA-interim climate reanalyses and high-resolution UK Met Office Africa Limited Area meteorological model (Africa-LAM) data. This initial search focusses on a selection of 13 candidate mountain peaks across Kenya. A mixture of 30 years (1981–2010) of relatively coarse-grained ERA-interim reanalyses data and 12 months’ (2011–2012) of much higher resolution UK Met Office Africa-LAM data were used to determine the best possible sites. Cloud cover, precipitable water vapour (specific humidity), vertical velocity, aerosol loadings and wind data were analysed. The results confirm that many sites in Kenya are reasonably cloud free, with estimated photometric night fractions of possibly 50 % at the best sites. Significant seasonal inter-annual and inter-decadal variations in cloud cover can be expected, however. Average precipitable water vapour (PWV) values are uncomfortably high, but periods of much lower PWV can be expected during favourable conditions in the dry seasons. Long-term vertical velocities (as a proxy to determine areas of improved “seeing” conditions) indicate that good astronomical viewing conditions are likely to be dependent on the season and wind direction across Kenya. Finally, after full consideration of the climatological data, a trade-off is expected between the best possible site in climatological terms, and the practicalities of installing remote equipment in isolated, inaccessible areas with little or no infrastructure. © 2015, Springer-Verlag Wien."
"6602605638;6507705956;","The inter-annual distribution of cloudless days and nights in Abastumani: Coupling with cosmic factors and climate change",2016,"10.1016/j.jastp.2015.10.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944089161&doi=10.1016%2fj.jastp.2015.10.004&partnerID=40&md5=550c04b987f4225387d0f8e26fdd5b8c","We examined inter-annual variations and long-term trends of cloudless days (CD) and cloudless nights (CN) in 1957-1993 from Abastumani (41.75N, 42.82E), at different geomagnetic conditions and corresponding galactic cosmic rays (GCRs) flux changes. It showed possible influence of cosmic factors on cloud covering processes and, thus, climate change. It was demonstrated that (1) the inter-annual distribution of monthly mean values of planetary geomagnetic index Ap (for low and moderate disturbances) at CDs can be described by harmonic function with semiannual (with sharp maxima in March and September) and annual (with maximum in August) periodicities; (2) the inter-annual distribution of Ap index for CN has an additional maximum in June, where the largest decrease of GCR flux is observed. This phenomenon is expressed even stronger during Sudden Storm Commencement (SSC) events and strong geomagnetic disturbances (Ap≥50), when their relative numbers are the greatest and are accompanied by bigger reduction of GCRs flux; (3) the long-term trends of mean annual and mean seasonal values of Ap index and GCRs flux at CD and CN are estimated. It was detected that, for the latitudes of this region, long-term decreases (negative trends) of seasonal GCR flux are different at CD and CN, which could affect the radiative balance at the Earth's surface and, as a result, contribute to the climate change. © 2015 Elsevier Ltd."
"34976155900;7101874266;55669661800;57203492395;7202611735;57214962213;35240191000;","Scale interactions between the MJO and the western Maritime Continent",2016,"10.1175/JCLI-D-15-0557.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962226920&doi=10.1175%2fJCLI-D-15-0557.1&partnerID=40&md5=a2f79cd17e31c326a8dc6545c41f99f8","State-of-the-art regional climate model simulations that are able to resolve key mesoscale circulations are used, for the first time, to understand the interaction between the large-scale convective environment of the MJO and processes governing the strong diurnal cycle over the islands of the Maritime Continent (MC). Convection is sustained in the late afternoon just inland of the coasts because of sea breeze convergence. Previous work has shown that the variability in MC rainfall associated with the MJO is manifested in changes to this diurnal cycle; land-based rainfall peaks before the active convective envelope of the MJO reaches the MC, whereas oceanic rainfall rates peak while the active envelope resides over the region. The model simulations show that the main controls on oceanic MC rainfall in the early active MJO phases are the large-scale environment and atmospheric stability, followed by high oceanic latent heat flux forced by high near-surface winds in the later active MJO phases. Over land, rainfall peaks before the main convective envelope arrives (in agreement with observations), even though the large-scale convective environment is only moderately favorable for convection. The causes of this early rainfall peak are strong convective triggers from land-sea breeze circulations that result from high surface insolation and surface heating. During the peak MJO phases cloud cover increases and surface insolation decreases, which weakens the strength of the mesoscale circulations and reduces land-based rainfall, even though the large-scale environment remains favorable for convection at this time. Hence, scale interactions are an essential part of the MJO transition across the MC. © 2016 American Meteorological Society."
"56003715500;57202301596;56795979700;","Uncertainty in tropical rainfall projections: Atmospheric circulation effect and the Ocean Coupling",2016,"10.1175/jcli-d-15-0601.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994069432&doi=10.1175%2fjcli-d-15-0601.1&partnerID=40&md5=73b3e9d54d662df3cc0c45922eaadab6","Uncertainty in tropical rainfall projections under increasing radiative forcing is studied by using 26 models from phase 5 of the Coupled Model Intercomparison Project. Intermodel spread in projected rainfall change generally increases with interactive sea surface temperature (SST) warming in coupled models compared to atmospheric models with a common pattern of prescribed SST increase. Moisture budget analyses reveal that much of the model uncertainty in tropical rainfall projections originates from intermodel discrepancies in the dynamical contribution due to atmospheric circulation change. Intermodel singular value decomposition (SVD) analyses further show a tight coupling between the intermodel variations in SST warming pattern and circulation change in the tropics. In the zonal mean, the first SVD mode features an anomalous interhemispheric Hadley circulation, while the second mode displays an SST peak near the equator. The asymmetric mode is accompanied by a coupled pattern of wind-evaporation-SST feedback in the tropics and is further tied to interhemispheric asymmetric change in extratropical shortwave radiative flux at the top of the atmosphere. Intermodel variability in the tropical circulation change exerts a strong control on the spread in tropical cloud cover change and cloud radiative effects among models. The results indicate that understanding the coupling between the anthropogenic changes in SST pattern and atmospheric circulation holds the key to reducing uncertainties in projections of future changes in tropical rainfall and clouds. © 2016 American Meteorological Society."
"25121200200;56684495200;","Research highlights: Laboratory studies of the formation and transformation of atmospheric organic aerosols",2016,"10.1039/c6em90012g","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84968739559&doi=10.1039%2fc6em90012g&partnerID=40&md5=a858f8148a700e03350d6bafe2e7f745","Atmospheric particles are emitted from a variety of anthropogenic and natural precursors and have direct impacts on climate, by scattering solar irradiation and nucleating clouds, and on health, by causing oxidative stress in the lungs when inhaled. They may also form from gaseous precursors, creating complex mixtures of organic and inorganic material. The chemical composition and the physical properties of aerosols will evolve during their one-week lifetime which will consequently change their impact on climate and health. The heterogeneity of aerosols is difficult to model and thus atmospheric aerosol research strives to characterize the mechanisms involved in nucleating and transforming particles in the atmosphere. Recent advances in four laboratory studies of aerosol formation and aging are highlighted here. © The Royal Society of Chemistry 2016."
"54895951600;56194862000;6602102587;","Belowground responses to elevation in a changing cloud forest",2016,"10.1002/ece3.2025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959421682&doi=10.1002%2fece3.2025&partnerID=40&md5=85159035efe19a033a56ad24a17de1b6","Few studies have investigated how soil fungal communities respond to elevation, especially within TMCF (tropical montane cloud forests). We used an elevation gradient in a TMCF in Costa Rica to determine how soil properties, processes, and community composition of fungi change in response to elevation and across seasons. As elevation increased, soil temperature and soil pH decreased, while soil moisture and soil C:N ratios increased with elevation. Responses of these properties varied seasonally. Fungal abundance increased with elevation during wet and dry seasons. Fungal community composition shifted in response to elevation, and to a lesser extent by season. These shifts were accompanied by varying responses of important fungal functional groups during the wet season and the relative abundance of certain fungal phyla. We suggest that elevation and the responses of certain fungal functional groups may be structuring fungal communities along this elevation gradient. TMCF are ecosystems that are rapidly changing due to climate change. Our study suggests that these changes may affect how fungal communities are structured. © 2016 Published by John Wiley & Sons Ltd."
"7201771183;55724460500;7202612588;","Explicit precipitation-type diagnosis from a model using a mixed-phase bulk cloud-precipitation microphysics parameterization",2016,"10.1175/WAF-D-15-0136.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84965006484&doi=10.1175%2fWAF-D-15-0136.1&partnerID=40&md5=d0bc4acd58b7a37bbe1024d69bba588d","The Rapid Refresh (RAP) and High-Resolution Rapid Refresh (HRRR), both operational at NOAA's National Centers for Environmental Prediction (NCEP) use the Thompson et al. mixed-phase bulk cloud microphysics scheme. This scheme permits predicted surface precipitation to simultaneously consist of rain, snow, and graupel at the same location under certain conditions. Here, the explicit precipitation-type diagnostic method is described as used in conjunction with the Thompson et al. scheme in the RAP and HRRR models. The postprocessing logic combines the explicitly predicted multispecies hydrometeor data and other information from the model forecasts to produce fields of surface precipitation type that distinguish between rain and freezing rain, and to also portray areas of mixed precipitation. This explicit precipitation-type diagnostic method is used with the NOAA operational RAP and HRRR models. Verification from two winter seasons from 2013 to 2015 is provided against METAR surface observations. An example of this product from a January 2015 south-central United States winter storm is also shown. © 2016 American Meteorological Society."
"7006729638;","Climate influences on Vaal River flow",2016,"10.4314/wsa.v42i2.07","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964880827&doi=10.4314%2fwsa.v42i2.07&partnerID=40&md5=381fb9058fb375f5e06e0857dbca1129","A study of climatic influences on Vaal River discharge, near Johannesburg, South Africa, finds that peak summer flows in the period 1979-2014 coincide with ocean-atmosphere interaction in the east Atlantic. The analysis has three parts: inter-annual influences by correlation of summer discharge with climate fields, atmosphere and ocean composites of 14 peak flow months, and a case study flood in January 2010 and its regional scale forcing. Inter-annual links are established with low pressure over the east Atlantic and an eastward equatorial ocean current and suppressed upwelling in the northern Benguela. During the January 2010 flood in the Vaal River, flow increased to 2 801 m3/s. There was a low salinity plume and warm sea temperatures off Angola &gt; 29°C. A terrestrial vegetation fraction &gt; 0.6 and corresponding latent heat fluxes enriched NW-cloud bands over the Vaal River catchment, during the flood case study of January 2010. Comparison of (Pacific) Southern Oscillation and east Atlantic influence on Vaal River discharge reveals the former drives evaporative losses while the latter provides an advance warning of flow variability. © 2016, South African Water Research Commission. All rights reserved."
"57187569000;7404925923;","Relating Vegetation Dynamics to Climate Variables in Taiwan Using 1982-2012 NDVI3g Data",2016,"10.1109/JSTARS.2015.2511742","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961388776&doi=10.1109%2fJSTARS.2015.2511742&partnerID=40&md5=d5d638d2210eb982b65513702b2720ab","This research aims to improve our understanding of vegetation dynamics and associated climate variables in Taiwan by utilizing mean-variance analysis (MVA), relative directional persistence analysis, and Pearson's product moment correlation analysis on the Advanced Very High Resolution Radiometer (AVHRR)-derived NDVI3g data from 1982 to 2012. The results indicate a slightly increasing mean-normalized difference vegetation index (NDVI) value with a relatively higher variance during the 1990s and lower variance during the 2000s, which may be explained by the observed fluctuation in precipitation. Additionally, NDVI patterns are identified as increasing in the first half of the year and decreasing in the second half of the year. Spatially, decreasing patterns are observed in all regions except that the northern counties exhibit an increasing NDVI pattern supported by the observed increase in precipitation. Moreover, sunshine duration and temperature are positively correlated with NDVI, whereas precipitation and cloud amount exhibit a negative correlation with NDVI in Taiwan. In the context of global environmental change, this research highlights the utility of applying a combined spatial-temporal approach to remote sensing products. This is an approach with potential applications such as landscape management, conservation practice, and water resource management for policy makers and stakeholders in and beyond Taiwan. © 2016 IEEE."
"23476605400;57183609100;57202681173;","Using surrogate meteorological data to predict the hydrology of a water balance cover",2016,"10.1061/(ASCE)GT.1943-5606.0001437","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961124673&doi=10.1061%2f%28ASCE%29GT.1943-5606.0001437&partnerID=40&md5=a54023b23f832c2e44283c83f25686fe","The objective of this study was to evaluate strategies for addressing missing meteorological (MET) data when predicting the hydrology of a water balance cover for a waste-containment system using a variably-saturated flow code. Predicting the hydrology of water balance covers typically requires site-specific daily MET data, which may be only partially available (e.g., dew point temperature (Tdew), solar radiation (Rs), wind speed, and cloud cover frequently are only partly available). Thus, some of the input data may need to be estimated or surrogate data employed for hydrologic modeling. The influence of replacing missing MET data with estimates on hydrologic predictions was evaluated for a water balance cover in a semiarid climate. Substitution of single or multiple MET variables with long-term averages led to statistically similar predictions of annual percolation relative to percolation predicted using actual data. Replacing all MET variables (Tdew, Rs, wind speed, and cloud cover) with long-term averages underpredicted percolation by 25% (0.58 mm/year), on average, relative to percolation predicted with actual data. A strategy for estimating MET data via empirical techniques is described that includes estimating (1) Tdew = daily minimum temperature, (2) Rs with the Hargreaves and Samini model, (3) daily wind speed set equal to monthly averages, and (4) cloud cover estimated as a function of solar radiation. This surrogate MET data technique yielded modest overpredictions of annual percolation of 3 and 46% (0.07 and 1.08 mm/year) that were statistically similar to percolation predicted using actual data. © 2015 American Society of Civil Engineers."
"57189303624;56715576000;56977205400;7202507292;","Monitoring variations of dimethyl sulfide and dimethylsulfoniopropionate in seawater and the atmosphere based on sequential vapor generation and ion molecule reaction mass spectrometry",2016,"10.1039/c6em00065g","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84968799787&doi=10.1039%2fc6em00065g&partnerID=40&md5=02542c807d7331f4c39bcb3e3c1103bf","To monitor the fluctuations of dimethyl sulfur compounds at the seawater/atmosphere interface, an automated system was developed based on sequential injection analysis coupled with vapor generation-ion molecule reaction mass spectrometry (SIA-VG-IMRMS). Using this analytical system, dissolved dimethyl sulfide (DMSaq) and dimethylsulfoniopropionate (DMSP), a precursor to DMS in seawater, were monitored together sequentially with atmospheric dimethyl sulfide (DMSg). A shift from the equilibrium point between DMSaq and DMSg results in the emission of DMS to the atmosphere. Atmospheric DMS emitted from seawater plays an important role as a source of cloud condensation nuclei, which influences the oceanic climate. Water samples were taken periodically and dissolved DMSaq was vaporized for analysis by IMRMS. After that, DMSP was hydrolyzed to DMS and acrylic acid, and analyzed in the same manner as DMSaq. The vaporization behavior and hydrolysis of DMSP to DMS were investigated to optimize these conditions. Frequent (every 30 min) determination of the three components, DMSaq/DMSP (nanomolar) and DMSg (ppbv), was carried out by SIA-VG-IMRMS. Field analysis of the dimethyl sulfur compounds was undertaken at a coastal station, which succeeded in showing detailed variations of the compounds in a natural setting. Observed concentrations of the dimethyl sulfur compounds both in the atmosphere and seawater largely changed with time and similar variations were repeatedly observed over several days, suggesting diurnal variations in the DMS flux at the seawater/atmosphere interface. © The Royal Society of Chemistry 2016."
"54958151600;55715297700;55706213200;","Variability features of the width of the tropical belt from COSMIC radio occultation data",2016,"10.1007/s11430-015-5252-x","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84953377004&doi=10.1007%2fs11430-015-5252-x&partnerID=40&md5=6b2c6c137252616e7b6727d25ea5641e","In this work, we analyzed time-series and trends of the tropical belt edges and widths with three methods based on the tropopause using new global positioning system radio occultation (GPS RO) data from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission for September 2006–February 2014. The results from the three methods agreed well with previous studies and new features were found. To avoid the El Niño Southern Oscillation (ENSO) and Quasi-Biennial Oscillation (QBO) influence, we applied a simple multiple linear regression model to the monthly anomalies to obtain the tropical belt edges and width trends. During the study, we found equatorward movements of the tropical belt edges on both hemispheres. The narrowing of the tropical belt mainly occurred in the Pacific Ocean. We also found that the deseasonalized monthly anomalies of the tropical belt width were closely related with the ENSO and QBO. The tropical belt at a height of 15 km was mostly closely related with the ENSO. The correlations between the QBO and the tropical belt were consistent for the three methods. © 2016, Science China Press and Springer-Verlag Berlin Heidelberg."
"54901507000;7004154626;56910010100;35253736000;7801642681;6701874937;","Seasonal variability in aerosol, CCN and their relationship observed at a high altitude site in Western Ghats",2016,"10.1007/s00703-015-0406-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944593993&doi=10.1007%2fs00703-015-0406-0&partnerID=40&md5=df205b4fc5fcaef9a3eadab2122a6663","Atmospheric aerosols which serve as cloud condensation nuclei (CCN) are key elements of the hydrological cycle and climate. In the present work, aerosol–CCN variability and their relationship have been studied for the first time at Mahabaleshwar, a high altitude (1348 m AMSL) site in Western Ghats, using one year (June 2012–May 2013) of observations. Present study has been done in two sections in which first temporal variability (diurnal and seasonal) of aerosol and CCN has been analyzed. Later CCN to aerosol ratio and other microphysical properties have been investigated along with detail discussion on possible sources of aerosol. First part, i.e., diurnal variation in aerosol and CCN concentration has shown relatively higher values during early morning hours in monsoon season whereas in winter and pre-monsoon it was higher in the evening hours. Seasonal mean variation in aerosol and CCN (SS above 0.6 %) has shown higher (less) in monsoon (winter) season. Temporal variation reveals dominance of fine-mode aerosol during monsoon season over the study region. In the second part temporal variation of activation ratio, k value (exponent of CCN super-saturation spectra) and geometric mean aerosol diameter have been analyzed. Variation of activation ratio showed the ratio is higher in monsoon especially for SS 0.6–1 %. The analysis also showed high k value during monsoon season as compared to other seasons (pre-monsoon and winter) which may be due to dominance of hygroscopic aerosols in the maritime air masses from Arabian Sea and biogenic aerosol emissions from the wet forest. Analyzed mean aerosol diameter is much smaller during monsoon season with less variability compared to other seasons. Overall analysis showed that aerosol and CCN concentration was higher over this high altitude site despite of dominant sink processes such as cloud scavenging and washout mechanisms indicating local emissions and biogenic Volatile Organic Compounds (BVOC) emissions from wet forest as major sources. © 2015, Springer-Verlag Wien."
"7404125583;55750937700;","Regional differences in the surface energy budget over China: an evaluation of a selection of CMIP5 models",2016,"10.1007/s00704-015-1407-0","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84924236137&doi=10.1007%2fs00704-015-1407-0&partnerID=40&md5=67d1a54fb31c496cfdb334fa0978776c","The present study provides an evaluation of the regional differences over China in surface energy budget components as simulated by a selection of models from phase five of the Coupled Model Intercomparison Project (CMIP5), covering the period 1960–2005. Similarities and differences exist among the models in terms of both spatial and magnitude patterns. For climatology, the CMIP5 models show quite different spatial distributions of shortwave radiation and sensible heat flux. In terms of seasonal variation, the surface energy budgets are remarkably different between western and eastern China. The discrepancies in the seasonal variation of sensible heat flux are mainly attributable to temperature differences and wind speed, while those of shortwave radiation are caused by the seasonal variation in total cloud cover. Cloudiness is one of the most crucial parameters in estimating the surface energy budget. In addition, the study also reveals that the magnitudes of the various components show larger (more than two-fold) differences between western and eastern parts of China, especially in net longwave and upward shortwave radiation, as well as latent and sensible heat fluxes. The results for surface soil heat flux show that there is more incoming energy during spring and summer and more outgoing energy during fall and winter in both western and eastern China. Furthermore, compared to NCEP2 data, the ERA-40 reanalysis product produces results more similar to the multi-model ensemble mean for most components. © 2015, Springer-Verlag Wien."
"55216588300;6701676992;36011653700;7006933675;26431037300;","Daily states of the March-April east Pacific ITCZ in three decades of high-resolution satellite data",2016,"10.1175/JCLI-D-15-0224.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964912726&doi=10.1175%2fJCLI-D-15-0224.1&partnerID=40&md5=753e14b40d3b1b1a0cb20f5595d81ba9","Zonally elongated areas of cloudiness that make up the east Pacific intertropical convergence zone (ITCZ) can take on several configurations in instantaneous observations. A novel statistical model is used to automatically assess the daily state of the east Pacific ITCZ using infrared satellite images from 1980 to 2012. Four ITCZ states are defined based on ITCZ location relative to the equator: north (nITCZ) and south (sITCZ) of the equator, simultaneously north and south of the equator (dITCZ, for double ITCZ), and over the equator (eITCZ). A fifth ITCZ state is used to classify days when no zonally elongated area of cloudiness is present (aITCZ, for absent ITCZ). The ITCZ states can occur throughout the year (except for the eITCZ, which is not present during June-October), with the nITCZ state dominating in terms of frequency of occurrence. Interannual variability of the state distribution is large. The most striking variability in ITCZ states is observed in spring. During March-April, the dITCZ state occurs on average 34% of the time, second only to the nITCZ state (39%). Composites of observed infrared temperature and precipitation by ITCZ state reveal distinct spatial configurations of cloudiness and rainfall. Strong sea surface temperature anomalies are associated only with eITCZ and sITCZ and they correspond to El Niño and La Niña, respectively. However, all five ITCZ states are associated with distinct atmospheric circulation patterns. A connection is found between the ITCZ and the South Pacific convergence zone (SPCZ), such that activity in the SPCZ is enhanced when the ITCZ is absent in the east Pacific. © 2016 American Meteorological Society."
"56545372500;7801692677;57200237025;","Long-term changes of meteorological conditions of urban heat island development in the region of Debrecen, Hungary",2016,"10.1007/s00704-015-1427-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84924598402&doi=10.1007%2fs00704-015-1427-9&partnerID=40&md5=93d7ecc0ccf1a796fd68a872aa2ef556","Meteorological conditions have a remarkable impact on urban climate similarly to other local and microscale climates. Clear skies and calm weather are advantageous for the development of the urban heat island (UHI). There are numerous studies on the spatial and temporal features of the phenomenon. Much less attention is paid, however, to the meteorological conditions of UHI development. The aim of the present paper is to reveal the characteristics of the changes in the frequencies of advantageous and disadvantageous meteorological conditions for UHI development on the basis of a 50-year-long time series. Meteorological condition categories of UHI development have been established on the basis of wind speed values, cloudiness, and precipitation ranging from advantageous to disadvantageous conditions. Frequencies of occurrence of condition categories of UHI development were determined first. Advantageous and moderately advantageous conditions were found to be dominant in the time series. Linear trend analysis revealed a significant increasing trend in the time series of advantageous conditions. Increase of the frequencies of advantageous conditions was analyzed for the years, seasons, and months of the study period as well. Spring and summer (April and June) produced significant increasing trends of frequencies of advantageous conditions, while winter (with the exception of February) and autumn did not show significant increase of those frequencies. Change-point analyses detected a significant increase in the frequency of advantageous conditions in the time series at the turn of 1981/1982 especially in the summer and spring months. Detected tendencies have negative effects on urban energy consumption: they contribute to the increase of air conditioning energy demand in the summer and do not decrease the energy demand of heating in the winter significantly. © 2015, Springer-Verlag Wien."
"55698400500;9533303700;57189004422;35616300500;6506260223;8509152300;8545189600;","Aerodynamic roughness of glacial ice surfaces derived from high-resolution topographic data",2016,"10.1002/2015JF003759","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964636319&doi=10.1002%2f2015JF003759&partnerID=40&md5=17f4130b85ee7362ace43d2f6c222f93","This paper presents new methods of estimating the aerodynamic roughness (z0) of glacier ice directly from three-dimensional point clouds and digital elevation models (DEMs), examines temporal variability of z0, and presents the first fully distributed map of z0 estimates across the ablation zone of an Arctic glacier. The aerodynamic roughness of glacier ice surfaces is an important component of energy balance models and meltwater runoff estimates through its influence on turbulent fluxes of latent and sensible heat. In a warming climate these fluxes are predicted to become more significant in contributing to overall melt volumes. Ice z0 is commonly estimated from measurements of ice surface microtopography, typically from topographic profiles taken perpendicular to the prevailing wind direction. Recent advances in surveying permit rapid acquisition of high-resolution topographic data allowing revision of assumptions underlying conventional z0 measurement. Using Structure from Motion (SfM) photogrammetry with Multi-View Stereo (MVS) to survey ice surfaces with millimeter-scale accuracy, z0 variation over 3 orders of magnitude was observed. Different surface types demonstrated different temporal trajectories in z0 through 3 days of intense melt. A glacier-scale 2 m resolution DEM was obtained through terrestrial laser scanning (TLS), and subgrid roughness was significantly related to plot-scale z0. Thus, we show for the first time that glacier-scale TLS or SfM-MVS surveys can characterize z0 variability over a glacier surface potentially leading to distributed representations of z0 in surface energy balance models. ©2016. American Geophysical Union. All Rights Reserved."
"35811219800;56346781400;36699321300;","Relationships of physiologically equivalent temperature and hospital admissions due to I30–I51 other forms of heart disease in Germany in 2009–2011",2016,"10.1007/s11356-015-5727-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84948948223&doi=10.1007%2fs11356-015-5727-5&partnerID=40&md5=be533cfbc453f5c851a9d1d58cd4c80d","We aimed to understand relationships of the weather as biometeorological and hospital admissions due to other forms of heart disease by subtypes, which have been paid less attention, in a national setting in recent years. This is an ecological study. Ten percent of daily hospital admissions of the included hospitals (n = 1618) across Germany that were available between 1 January 2009 and 31 December 2011 (n = 5,235,600) were extracted from Statistisches Bundesamt, Germany. We identified I30–I51 other forms of heart disease by the International Classification of Diseases version 10 as the study outcomes. Daily weather data from 64 weather stations that have covered 13 German states, including air temperature, humidity, wind speed, cloud cover, radiation flux and vapour pressure, were obtained and generated into physiologically equivalent temperature (PET). Admissions due to other diseases of pericardium, nonrheumatic mitral valve disorders, nonrheumatic aortic valve disorders, cardiomyopathy, atrioventricular and left bundle-branch block, other conduction disorders, atrial fibrillation and flutter, and other cardiac arrhythmias peaked when PET was between 0 and 10 °C. Complications and ill-defined descriptions of heart disease admissions peaked at PET 0 °C. Cardiac arrest and heart failure admissions peaked when PET was between 0 and −10 °C while the rest did not vary significantly. A common drop of admissions was found when PET was above 10 °C. More medical resources could have been needed for heart health on days when PETs were <10 °C than on other days. Adaptation to such weather change for medical professionals and the general public would seem to be imperative. © 2015, The Author(s)."
"7201798956;57195769430;7006091410;6602377428;12775969000;6603818553;36700435900;","The summer diurnal cycle of coastal cloudiness over west Iberia using Meteosat/SEVIRI and a WRF regional climate model simulation",2016,"10.1002/joc.4457","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973575301&doi=10.1002%2fjoc.4457&partnerID=40&md5=e963887cab10ffec0f72c8d7a2df478d","The summer time cloud diurnal cycle over western Iberia is analysed here using a satellite climate data record of fractional cloud cover based on 9 years of Meteosat Second Generation observations which is distributed by the EUMETSAT's Climate Monitoring Satellite Applications Facility. These observations were complemented with a corresponding mean cloud diurnal cycle using SYNOP reports on six locations over the studied domain. It is shown that the main coastal mountain range separates regions that are characterized by two very different cloud regimes: stratocumulus-topped boundary layer convection dominates the region towards the coast and continental cumulus convection dominates the region to the east of these mountains. To explain the observed variability, a long-term regional climate model [Weather Research and Forecasting model (WRF)] simulation over Iberia was used. A comparison of the observations against model output for the common period between observations and simulation shows that although the model generally underestimates cloudiness, it is able to represent the diurnal cycle in a realistic manner. It is shown that the observed cloud diurnal evolution is linked to the thermal circulations generated by the land-sea contrast and orography. The extent to which the cloud deck penetrates inland is closely related to the coastal orography: although smaller hills tend to enhance cloudiness, larger mountains block the progression of the marine boundary layer further inland, as it behaves as a density current. Larger mountains also produce katabatic flow and a rather strong subsidence aloft during the night. The warming due to this subsidence helps the blocking of the cloud deck as it is partially responsible for evaporating clouds, as shown by a potential temperature budget analysis. © 2016 Royal Meteorological Society."
"8970971200;6603775815;8359591200;57131366300;","Challenges associated with the sampling and analysis of organosulfur compounds in air using real-time PTR-ToF-MS and offline GC-FID",2016,"10.5194/amt-9-1325-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962338911&doi=10.5194%2famt-9-1325-2016&partnerID=40&md5=14b681888b2a0533d9f55b43e649f343","Organosulfur compounds (OSCs) are naturally emitted via various processes involving phytoplankton and algae in marine regions, from animal metabolism, and from biomass decomposition inland. These compounds are malodorant and reactive. Their oxidation to methanesulfonic and sulfuric acids leads to the formation and growth of atmospheric particles, which are known to influence clouds and climate, atmospheric chemical processes. In addition, particles in air have been linked to negative impacts on visibility and human health. Accurate measurements of the OSC precursors are thus essential to reduce uncertainties in their sources and contributions to particle formation in air. Two different approaches, proton-transfer reaction time-of-flight mass spectrometry (PTR-ToF-MS) and canister sampling coupled to gas chromatography with flame ionization detector (GC-FID), are compared for both laboratory standards (dimethyl sulfide, DMS; dimethyl disulfide, DMDS; dimethyl trisulfide, DMTS; and methanethiol, MTO) and for a complex sample. Results show that both techniques produce accurate quantification of DMS. While PTR-ToF-MS provides real-time measurements of all four OSCs individually, significant fragmentation of DMDS and DMTS occurs, which can complicate their identification in complex mixtures. Canister sampling coupled with GC-FID provides excellent sensitivity for DMS, DMDS, and DMTS. However, MTO was observed to react on metal surfaces to produce DMDS and, in the presence of hydrogen sulfide, even DMTS. Avoiding metal in sampling systems seems to be necessary for measuring all but dimethyl sulfide in air. © Author(s) 2016."
"7003284044;6701365566;55964335800;6603413684;56682052600;","Changes in the large-scale thermodynamic instability and connection with rain shower frequency over Romania: Verification of the Clausius-Clapeyron scaling",2016,"10.1002/joc.4477","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958025952&doi=10.1002%2fjoc.4477&partnerID=40&md5=e708f7f2fbcae425593b4811bf55af82","The goal of this article is twofold: first, changes in the spring and summer thermodynamic instability over the North Atlantic European region and the connection with frequency of rain showers at 81 locations across Romania for the period 1961-2010 are analysed; second, the relationship between hourly precipitation extremes and air temperature with respect to the validity of Clausius-Clapeyron (CC) scaling is investigated. The Best Lifted Index (lftx4) has been selected to quantify the thermodynamic instability. The mechanisms responsible for the rain showers' variability in Romania were analysed using the canonical correlation analysis (CCA). Results show that the regional distribution of the lftx4 changes is quite similar in the two seasons, with a transition towards thermodynamic stability over most of Mediterranean regions - central Europe and instability in northern Europe, Black Sea, North Atlantic (summer), southern North Atlantic (spring). The frequency of rain showers in Romania exhibits a significant increasing trend in both seasons, which is in agreement with the increase in frequency of Cumulonimbus clouds. In contrast, the frequency of rainfall days does not exhibit any significant trend that shows a shift in the nature of precipitation towards more showers. The CCA shows that the optimum large-scale mechanisms responsible for this behaviour are given by the first CCA pair with the lftx4 pattern represented by a dipole structure with a nucleus of thermodynamic instability centred over Romania. The dynamic factor is an additional ingredient for spring, as precipitable water is for summer. The extreme hourly rainfall intensities reveal a similar behaviour over the entire country: the 90th percentile shows dependence close to the CC relation for all temperatures; the 99th and 99.9th percentiles exhibit rates close to double the CC rate for temperatures between ∼10 and ∼22 °C and negative scaling rates for higher temperatures. The daily intensities have a less clearly defined scaling behaviour. © 2016 Royal Meteorological Society."
"57188742108;36465124400;56919576300;24554058600;7006252685;7006377579;9043417100;57195257572;7006235542;","Size-segregated compositional analysis of aerosol particles collected in the European Arctic during the ACCACIA campaign",2016,"10.5194/acp-16-4063-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962649580&doi=10.5194%2facp-16-4063-2016&partnerID=40&md5=976f362d56617b86a5223364e96fdc86","Single-particle compositional analysis of filter samples collected on board the Facility for Airborne Atmospheric Measurements (FAAM) BAe-146 aircraft is presented for six flights during the springtime Aerosol-Cloud Coupling and Climate Interactions in the Arctic (ACCACIA) campaign (March-April 2013). Scanning electron microscopy was utilised to derive size-segregated particle compositions and size distributions, and these were compared to corresponding data from wing-mounted optical particle counters. Reasonable agreement between the calculated number size distributions was found. Significant variability in composition was observed, with differing external and internal mixing identified, between air mass trajectory cases based on HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) analyses. Dominant particle classes were silicate-based dusts and sea salts, with particles notably rich in K and Ca detected in one case. Source regions varied from the Arctic Ocean and Greenland through to northern Russia and the European continent. Good agreement between the back trajectories was mirrored by comparable compositional trends between samples. Silicate dusts were identified in all cases, and the elemental composition of the dust was consistent for all samples except one. It is hypothesised that long-range, high-altitude transport was primarily responsible for this dust, with likely sources including the Asian arid regions. © 2016 Author(s). CC Attribution 3.0 License."
"35494005000;57188733928;","Observational evidence for aerosol invigoration in shallow cumulus downstream of Mount Kilauea",2016,"10.1002/2016GL067830","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979469566&doi=10.1002%2f2016GL067830&partnerID=40&md5=eedc045d2ae6ebdeb7e21121f3fe8ff0","Knowledge of how marine boundary layer (MBL) shallow cumulus clouds respond to changes in aerosol is central to understanding how MBL clouds modulate the climate system. Mount Kilauea on the island of Hawaii began erupting in 2008 injecting substantial SO2 into the marine boundary layer creating a unique natural laboratory. Examining data from approximately 600 passes of the A-Train downstream of Mount Kilauea over a 3 year period and separating data into aerosol optical depth quartiles, we find an unambiguous increase in marine boundary cloud top height and an increase in surface wind speed as aerosol increases while the radar reflectivity does not change substantially. We conclude that increased aerosols may have caused invigoration of the MBL clouds. Additionally, we find that increases in sub 1 km cloud fraction combined with increasing aerosol explain the increased visible reflectance suggesting that evidence for the so-called first aerosol indirect effect should be reexamined. ©2016. American Geophysical Union. All Rights Reserved."
"56463161500;15051249600;55535058500;55357667300;57188829283;","Transmission and division of total optical depth method: A universal calibration method for Sun photometric measurements",2016,"10.1002/2016GL068031","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979493138&doi=10.1002%2f2016GL068031&partnerID=40&md5=c9bb182e3860c6090788eebd1c72aef0","Sun photometric measurements, which provide accurate and timely information on atmospheric components such as aerosols, clouds, and gases are important to climate research. For regions with heavy and variable aerosol loading, the traditional Langley plot method cannot be applied for Sun photometric instrument calibration, as almost no suitable prolonged periods with stable atmosphere and low-aerosol loading occurs. An improved calibration method, namely, the transmission and division of total optical depth method, is proposed in this study. Atmospheric total optical depth variation information obtained via other methods is transmitted, and period groups with similar atmospheric extinction effects are selected for Langley regression. This method is validated through calibration of a multifilter rotating shadowband radiometer under heavy aerosol-loading conditions. The obtained aerosol optical depth (AOD) compares well with the interpolated AOD from a Cimel Sun-sky radiometer. ©2016. American Geophysical Union. All Rights Reserved."
"36701462300;10243650000;55686667100;57202301596;36728564200;","Robust cloud feedback over tropical land in a warming climate",2016,"10.1002/2015JD024525","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964555392&doi=10.1002%2f2015JD024525&partnerID=40&md5=372a56f15a766a67aea21bea4bc334c8","Cloud-related radiative perturbations over land in a warming climate are of importance for human health, ecosystem, agriculture, and industry via solar radiation availability and local warming amplification. However, robustness and physical mechanisms responsible for the land cloud feedback were not examined sufficiently because of the limited contribution to uncertainty in global climate sensitivity. Here we show that cloud feedback in general circulation models over tropical land is robust, positive, and is relevant to atmospheric circulation change and thermodynamic constraint associated with water vapor availability. In a warming climate, spatial variations in tropospheric warming associated with climatological circulation pattern result in a general weakening of tropical circulation and a dynamic reduction of land cloud during summer monsoon season. Limited increase in availability of water vapor also reduces the land cloud. The reduction of land cloud depends on global-scale oceanic warming and is not sensitive to regional warming patterns. The robust positive feedback can contribute to the warming amplification and drying over tropical land in the future. © 2016. American Geophysical Union. All Rights Reserved."
"57196143493;57188745140;36553486200;","Inhomogeneous radiative forcing of homogeneous greenhouse gases",2016,"10.1002/2015JD024569","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962674006&doi=10.1002%2f2015JD024569&partnerID=40&md5=be727b37be7f3a3106ebf768cbd7dc9f","Radiative forcing of a homogeneous greenhouse gas (HGG) can be very inhomogeneous because the forcing is dependent on other atmospheric and surface variables. In the case of doubling CO2, the monthly mean instantaneous forcing at the top of the atmosphere is found to vary geographically and temporally from positive to negative values, with the range (-2.5–5.1 W m-2) being more than 3 times the magnitude of the global mean value (2.3 W m-2). The vertical temperature change across the atmospheric column (temperature lapse rate) is found to be the best single predictor for explaining forcing variation. In addition, the masking effects of clouds and water vapor also contribute to forcing inhomogeneity. A regression model that predicts forcing from geophysical variables is constructed. This model can explain more than 90% of the variance of the forcing. Applying this model to analyzing the forcing variation in the Climate Model Intercomparison Project Phase 5 models, we find that intermodel discrepancy in CO2 forcing caused by model climatology leads to considerable discrepancy in their projected change in poleward energy transport. © 2016. American Geophysical Union. All Rights Reserved."
"54400559100;6603400519;6602506180;7006743561;7003627515;","A Retrospective, Iterative, Geometry-Based (RIGB) tilt-correction method for radiation observed by automatic weather stations on snow-covered surfaces: Application to Greenland",2016,"10.5194/tc-10-727-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964047114&doi=10.5194%2ftc-10-727-2016&partnerID=40&md5=575c1bb4ecc9b82280a6d490dafa82e2","Surface melt and mass loss of the Greenland Ice Sheet may play crucial roles in global climate change due to their positive feedbacks and large fresh-water storage. With few other regular meteorological observations available in this extreme environment, measurements from automatic weather stations (AWS) are the primary data source for studying surface energy budgets, and for validating satellite observations and model simulations. Station tilt, due to irregular surface melt, compaction and glacier dynamics, causes considerable biases in the AWS shortwave radiation measurements. In this study, we identify tilt-induced biases in the climatology of surface shortwave radiative flux and albedo, and retrospectively correct these by iterative application of solar geometric principles. We found, over all the AWS from the Greenland Climate Network (GC-Net), the Kangerlussuaq transect (K-transect) and the Programme for Monitoring of the Greenland Ice Sheet (PROMICE) networks, insolation on fewer than 40% of clear days peaks within &pm;0.5h of solar noon time, with the largest shift exceeding 3h due to tilt. Hourly absolute biases in the magnitude of surface insolation can reach up to 200W m-2, with respect to the well-understood clear-day insolation. We estimate the tilt angles and their directions based on the solar geometric relationship between the simulated insolation at a horizontal surface and the observed insolation by these tilted AWS under clear-sky conditions. Our adjustment reduces the root mean square error (RMSE) against references from both satellite observation and reanalysis by 16W m-2 (24%), and raises the correlation coefficients with them to above 0.95. Averaged over the whole Greenland Ice Sheet in the melt season, the adjustment in insolation to compensate station tilt is ∼ 11W m-2, enough to melt 0.24m of snow water equivalent. The adjusted diurnal cycles of albedo are smoother, with consistent semi-smiling patterns. The seasonal cycles and inter-annual variabilities of albedo agree better with previous studies. This tilt-corrected shortwave radiation data set derived using the Retrospective, Iterative, Geometry-Based (RIGB) method provide more accurate observations and validations for surface energy budgets studies on the Greenland Ice Sheet, including albedo variations, surface melt simulations and cloud radiative forcing estimates. © Author(s) 2016."
"8728433200;7501381728;12806862100;6506180220;35519380200;55683891800;13405658600;","Processes controlling the annual cycle of Arctic aerosol number and size distributions",2016,"10.5194/acp-16-3665-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962232181&doi=10.5194%2facp-16-3665-2016&partnerID=40&md5=0a22c50f6cd0774c92544baa98bf6c0d","Measurements at high-Arctic sites (Alert, Nunavut, and Mt. Zeppelin, Svalbard) during the years 2011 to 2013 show a strong and similar annual cycle in aerosol number and size distributions. Each year at both sites, the number of aerosols with diameters larger than 20 nm exhibits a minimum in October and two maxima, one in spring associated with a dominant accumulation mode (particles 100 to 500 nm in diameter) and a second in summer associated with a dominant Aitken mode (particles 20 to 100 nm in diameter). Seasonal-mean aerosol effective diameter from measurements ranges from about 180 in summer to 260 nm in winter. This study interprets these annual cycles with the GEOS-Chem-TOMAS global aerosol microphysics model. Important roles are documented for several processes (new-particle formation, coagulation scavenging in clouds, scavenging by precipitation, and transport) in controlling the annual cycle in Arctic aerosol number and size. Our simulations suggest that coagulation scavenging of interstitial aerosols in clouds by aerosols that have activated to form cloud droplets strongly limits the total number of particles with diameters less than 200 nm throughout the year. We find that the minimum in total particle number in October can be explained by diminishing new-particle formation within the Arctic, limited transport of pollution from lower latitudes, and efficient wet removal. Our simulations indicate that the summertime-dominant Aitken mode is associated with efficient wet removal of accumulation-mode aerosols, which limits the condensation sink for condensable vapours. This in turn promotes new-particle formation and growth. The dominant accumulation mode during spring is associated with build up of transported pollution from outside the Arctic coupled with less-efficient wet-removal processes at colder temperatures. We recommend further attention to the key processes of new-particle formation, interstitial coagulation, and wet removal and their delicate interactions and balance in size-resolved aerosol simulations of the Arctic to reduce uncertainties in estimates of aerosol radiative effects on the Arctic climate."
"11539061800;26428178700;7003922583;","Shortwave surface radiation network for observing small-scale cloud inhomogeneity fields",2016,"10.5194/amt-9-1153-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961837289&doi=10.5194%2famt-9-1153-2016&partnerID=40&md5=979e0e9cc455ebba3b37831c7bd51d23","As part of the High Definition Clouds and Precipitation for advancing Climate Prediction Observational Prototype Experiment (HOPE), a high-density network of 99 silicon photodiode pyranometers was set up around Jülich (10km×12km area) from April to July 2013 to capture the small-scale variability of cloud-induced radiation fields at the surface. In this paper, we provide the details of this unique setup of the pyranometer network, data processing, quality control, and uncertainty assessment under variable conditions. Some exemplary days with clear, broken cloudy, and overcast skies were explored to assess the spatiotemporal observations from the network along with other collocated radiation and sky imager measurements available during the HOPE period. © Author(s) 2016."
"55894937000;7401776640;","Reducing the uncertainty in subtropical cloud feedback",2016,"10.1002/2015GL067416","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959571378&doi=10.1002%2f2015GL067416&partnerID=40&md5=0c98b3ca6d7465e8da98f9bfc58393c7","Large uncertainty remains on how subtropical clouds will respond to anthropogenic climate change and therefore whether they will act as a positive feedback that amplifies global warming or negative feedback that dampens global warming by altering Earth's energy budget. Here we reduce this uncertainty using an observationally constrained formulation of the response of subtropical clouds to greenhouse forcing. The observed interannual sensitivity of cloud solar reflection to varying meteorological conditions suggests that increasing sea surface temperature and atmospheric stability in the future climate will have largely canceling effects on subtropical cloudiness, overall leading to a weak positive shortwave cloud feedback (0.4 ± 0.9 W m-2 K-1). The uncertainty of this observationally based approximation of the cloud feedback is narrower than the intermodel spread of the feedback produced by climate models. Subtropical cloud changes will therefore complement positive cloud feedbacks identified by previous work, suggesting that future global cloud changes will amplify global warming. ©2016. American Geophysical Union. All Rights Reserved."
"7401837691;57161563900;56729650300;56730290100;","Observed and projected decrease in Northern Hemisphere extratropical cyclone activity in summer and its impacts on maximum temperature",2016,"10.1002/2016GL068172","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960365132&doi=10.1002%2f2016GL068172&partnerID=40&md5=83a2c939324b2024e3a2c05b1067fd93","Extratropical cyclones cause much of the high-impact weather over the midlatitudes. With increasing greenhouse gases, enhanced high-latitude warming will lead to weaker cyclone activity. Here we show that between 1979 and 2014, the number of strong cyclones in Northern Hemisphere in summer has decreased at a rate of 4% per decade, with even larger decrease found near northeastern North America. Climate models project a decrease in summer cyclone activity, but the observed decreasing rate is near the fastest projected. Decrease in summer cyclone activity will lead to decrease in cloud cover, giving rise to higher maximum temperature, potentially enhancing the increase in maximum temperature by 0.5 K or more over some regions. We also show that climate models may have biases in simulating the positive relationship between cyclone activity and cloud cover, potentially underestimating the impacts of cyclone decrease on accentuating the future increase in maximum temperature. © 2016. American Geophysical Union. All Rights Reserved."
"57160391500;16637291100;55977336000;","The influence of winter cloud on summer sea ice in the Arctic, 1983–2013",2016,"10.1002/2015JD024316","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960153939&doi=10.1002%2f2015JD024316&partnerID=40&md5=c51f164437f3fe15750866196d2e9fb1","Arctic sea ice extent has declined dramatically over the last two decades, with the fastest decrease and greatest variability in the Beaufort, Chukchi, and East Siberian Seas. Thinner ice in these areas is more susceptible to changes in cloud cover, heat and moisture advection, and surface winds. Using two climate reanalyses and satellite data, it is shown that increased wintertime surface cloud forcing contributed to the 2007 summer sea ice minimum. An analysis over the period 1983–2013 reveals that reanalysis cloud forcing anomalies in the East Siberian and Kara Seas precondition the ice pack and, as a result, explain 25% of the variance in late summer sea ice concentration. This finding was supported by Moderate Resolution Imaging Spectroradiometer cloud cover anomalies, which explain up to 45% of the variance in sea ice concentration. Results suggest that winter cloud forcing anomalies in this area have predictive capabilities for summer sea ice anomalies across much of the central and Eurasian Arctic. ©2016. American Geophysical Union. All Rights Reserved."
"23389689400;7005413744;36023718600;26654147000;8598454000;","Earlier green-up and spring warming amplification over Europe",2016,"10.1002/2016GL068062","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977963093&doi=10.1002%2f2016GL068062&partnerID=40&md5=05c44a04495744272eea7854b8888550","The onset of green-up of plants has advanced in response to climate change. This advance has the potential to affect heat waves via biogeochemical and biophysical processes. Here a climate model was used to investigate only the biophysical feedbacks of earlier green-up on climate as the biogeochemical feedbacks have been well addressed. Earlier green-up by 5 to 30 days amplifies spring warming in Europe, especially heat waves, but makes few differences to heat waves in summer. This spring warming is most noticeable within 30 days of advanced green-up and is associated with a decrease in low- A nd middle-layer clouds and associated increases of downward short wave and net radiation. We find negligible differences in the Southern Hemisphere and low latitudes of the Northern Hemisphere. Our results provide an estimate of the level of skill necessary in phenology models to avoid introducing biases in climate simulations. © 2016. American Geophysical Union. All Rights Reserved."
"7402838215;55469200300;55801231800;6506848120;15726759700;57188729343;36106191000;6506126751;35595682100;7201951829;7005960178;7004740995;57204252724;7005941217;54393349200;7003763119;","A microphysics guide to cirrus clouds-Part 1: Cirrus types",2016,"10.5194/acp-16-3463-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962486253&doi=10.5194%2facp-16-3463-2016&partnerID=40&md5=50f013840ffd8985b1db03cf5badefb5","The microphysical and radiative properties of cirrus clouds continue to be beyond understanding and thus still represent one of the largest uncertainties in the prediction of the Earth's climate (IPCC, 2013). Our study aims to provide a guide to cirrus microphysics, which is compiled from an extensive set of model simulations, covering the broad range of atmospheric conditions for cirrus formation and evolution. The model results are portrayed in the same parameter space as field measurements, i.e., in the Ice Water Content-Temperature (IWC-T) parameter space. We validate this cirrus analysis approach by evaluating cirrus data sets from 17 aircraft campaigns, conducted in the last 15 years, spending about 94 h in cirrus over Europe, Australia, Brazil as well as South and North America. Altogether, the approach of this study is to track cirrus IWC development with temperature by means of model simulations, compare with observations and then assign, to a certain degree, cirrus microphysics to the observations. Indeed, the field observations show characteristics expected from the simulated Cirrus Guide. For example, high (low) IWCs are found together with high (low) ice crystal concentrations <i>N</i>ice. <br><br> An important finding from our study is the classification of two types of cirrus with differing formation mechanisms and microphysical properties: the first cirrus type forms directly as ice (in situ origin cirrus) and splits in two subclasses, depending on the prevailing strength of the updraft: in slow updrafts these cirrus are rather thin with lower IWCs, while in fast updrafts thicker cirrus with higher IWCs can form. The second type consists predominantly of thick cirrus originating from mixed phase clouds (i.e., via freezing of liquid droplets-liquid origin cirrus), which are completely glaciated while lifting to the cirrus formation temperature region (&lt; 235 K). In the European field campaigns, slow updraft in situ origin cirrus occur frequently in low-and high-pressure systems, while fast updraft in situ cirrus appear in conjunction with jet streams or gravity waves. Also, liquid origin cirrus mostly related to warm conveyor belts are found. In the US and tropical campaigns, thick liquid origin cirrus which are formed in large convective systems are detected more frequently. © 2016 Author(s)."
"22935673400;6602999057;9536598800;6603327055;12042447700;","Modeling haboob dust storms in large-scale weather and climate models",2016,"10.1002/2015JD024349","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959520243&doi=10.1002%2f2015JD024349&partnerID=40&md5=2fced5b0c274d6579458e486f84a47dd","Recent field campaigns have shown that haboob dust storms, formed by convective cold pool outflows, contribute a significant fraction of dust uplift over the Sahara and Sahel in summer. However, in situ observations are sparse and haboobs are frequently concealed by clouds in satellite imagery. Furthermore, most large-scale weather and climate models lack haboobs, because they do not explicitly represent convection. Here a 1 year long model run with explicit representation of convection delivers the first full seasonal cycle of haboobs over northern Africa. Using conservative estimates, the model suggests that haboobs contribute one fifth of the annual dust-generating winds over northern Africa, one fourth between May and October, and one third over the western Sahel during this season. A simple parameterization of haboobs has recently been developed for models with parameterized convection, based on the downdraft mass flux of convection schemes. It is applied here to two model runs with different horizontal resolutions and assessed against the explicit run. The parameterization succeeds in capturing the geographical distribution of haboobs and their seasonal cycle over the Sahara and Sahel. It can be tuned to the different horizontal resolutions, and different formulations are discussed with respect to the frequency of extreme events. The results show that the parameterization is reliable and may solve a major and long-standing issue in simulating dust storms in large-scale weather and climate models. ©2016. American Geophysical Union. All Rights Reserved."
"55522498000;14920052300;55802246600;57169158900;55544020300;","Climatic effects of irrigation over the Huang-Huai-Hai plain in China simulated by the weather research and forecasting model",2016,"10.1002/2015JD023736","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960847662&doi=10.1002%2f2015JD023736&partnerID=40&md5=7e534805d7e98b77d33a55034a337ced","The climatic effects of irrigation over the Huang-Huai-Hai Plain (3HP) in China are investigated by using the weather research and forecasting model coupled with an operational-like irrigation scheme. Multiple numerical experiments with irrigation off/on during spring, summer, and both spring and summer are conducted. Results show that the warm bias in surface temperature and dry bias in soil moisture are reduced over the 3HP region during the growing seasons by considering the irrigation in the model. The air temperature during nongrowing seasons is also affected by irrigation because of the persistent effects of soil moisture on land-air energy exchanges and ground heat storage. Irrigation can induce significant cooling in the planetary boundary layer (PBL) during the growing seasons and lead to a relatively wet PBL with increased low-level clouds during spring but a relatively dry condition in summer. Further analyses indicate that irrigation leads to increased summer precipitation over the Yangtze River Basin and decreased summer precipitation in southern and northern China. These responses are associated with the changes in the large-scale circulation induced by irrigation. Irrigation tends to cool the atmosphere and forces a possible southward shift of the upper level jet that can further affect the precipitation distribution. Our model results suggest that in addition to local-scale processes, large-scale impacts should also be considered when studying the precipitation response to irrigation over East Asia. ©2016. American Geophysical Union. All Rights Reserved."
"57161971500;7005217679;","Meteorological factors contributing to the interannual variability of midsummer surface ozone in Colorado, Utah, and other western U.S. states",2016,"10.1002/2015JD023840","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960368653&doi=10.1002%2f2015JD023840&partnerID=40&md5=0153f3ca221ef3b4c5c79071bd53d117","We use daily maximum 8 h average surface O3 concentrations (MDA8) for July 1995–2013, meteorological variables from the National Center for Environmental Prediction/National Center for Atmospheric Research Reanalysis, the North American Regional Reanalysis, and output from regional chemistry-climate simulations to assess relationships between O3 and weather in the western U.S. We also explore relationships among July O3, satellite-derived NO2, and meteorology. A primary objective of this study is to identify an effective method for correcting the effects of meteorology on July MDA8. We find significant correlations between July MDA8 O3 and meteorological variables for sites in or near Denver, Colorado, and Salt Lake City, Utah. The highest correlations were for 500 hPa heights, surface temperatures, and 700 hPa temperatures and zonal winds. We conclude that increased 500 hPa heights lead to high July O3 in much of the western U.S., particularly in areas of elevated terrain near urban sources of NO2 and other O3 precursors. In addition to bringing warmer temperatures and fewer clouds, upper level ridges decrease winds and allow cyclic terrain-driven circulations to reduce transport away from sources. Because of strong, nearly linear responses of July MDA8 to 500 hPa heights, it is not reasonable to use uncorrected trends in peak O3 for assessments of the effectiveness of emissions controls for much of the western U.S. Robust linear regressions for July MDA8 and tropospheric NO2 with 500 hPa heights can be used to assess and correct trends in July MDA8 in the Intermountain West. ©2016. American Geophysical Union. All Rights Reserved."
"55355176000;55796506900;55669799600;7410070663;25941200000;","Cloud overlapping parameter obtained from CloudSat/CALIPSO dataset and its application in AGCM with McICA scheme",2016,"10.1016/j.atmosres.2015.11.007","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949292773&doi=10.1016%2fj.atmosres.2015.11.007&partnerID=40&md5=d973eee4564f22c4cef8c68a5e9a98ac","Vertical decorrelation length (Lcf) as used to determine overlap of cloudy layers in GCMs was obtained from CloudSat/CALIPSO measurements, made between 2007 and 2010, and analyzed in terms of monthly means. Global distributions of Lcf were produced for several cross-sectional lengths. Results show that: Lcf over the tropical convective regions typically exceeds 2 km and shift meridionally with season; the smallest Lcf (&lt; 1 km) tends to occur in regions dominated by marine stratiform clouds; Lcf for mid-to-high latitude continents of the Northern Hemisphere (NH) ranges from 5-6 km during winter to 2-3 km during summer; and there are marked differences between continental and oceanic values of Lcf in the mid-latitudes of the NH.These monthly-gridded, observationally-based values of Lcf data were then used by the Monte Carlo Independent Column Approximation (McICA) radiation routines within the Beijing Climate Center's GCM (BCC_AGCM2.0.1). Additionally, the GCM was run with two other descriptions of Lcf: one varied with latitude only, and the other was simply 2 km everywhere all the time. It is shown that using the observationally-based Lcf in the GCM led to local and seasonal changes in total cloud fraction and shortwave (longwave) cloud radiative effects that serve mostly to reduce model biases. This indicates that usage of Lcf that vary according to location and time has the potential to improve climate simulations. © 2015 Elsevier B.V."
"35857960400;7004940109;7003375121;7006313933;6701427386;","Solar activity cloudiness effect on NH warming for 1980-2095",2016,"10.1016/j.asr.2015.11.024","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959515010&doi=10.1016%2fj.asr.2015.11.024&partnerID=40&md5=efc31834d83ebd925bcea2faec7cf062","We use a Thermodynamic Climate Model (TCM) to compute the Northern Hemisphere temperature anomaly for the period 1980-2095, corresponding to the global warming (GW) by the increase of the atmospheric CO 2 ; the GW is in turn diminished as a consequence of the negative anomaly of the solar activity (SA), giving a warming reduction (WR). So the CO 2 and the SA represent external climate forcings. The total solar irradiance (TSI) is the main manifestation of the SA and of course is the climate driver; the SA produces besides the solar wind that modulates the flux of galactic cosmic rays (GCR), which in turn modifies the low cloud cover, that by itself influences inversely the mid cloud cover; the combination of both cloudiness yields the so called relevant cloud cover. The GCR-cloudiness effect has a delay of ∼1 yr with respect to TSI effect, which is the time for a SA change to reach the heliopause carried by the solar wind. In order to incorporate this climate mechanism, the TCM now includes the warming due to the vapor condensation by GCR, which causes a decrease in the magnitude of the WR. The TCM was improved by incorporating it new parameterizations of three mechanisms, which are activated by the GW: the atmospheric lapse rate changes; the water vapor emissivity between 8 and 12.5μ is computed with the E-Trans/HITRAN calculator; and changes in this emissivity band according to the relative humidity changes. The 11-yr variability of the TSI time series is filtered to get the trend along 21st century. Two IPCC (2001, 2007) CO 2 emission scenarios are used: the high A1FI and the low A1T. Emphasis is made on the results for two particular years: one corresponding to the deepest part of the TSI grand solar minimum in the year 2029, and the other to the end of the century, 2095. The main thermal feedbacks included in TCM are those due to the atmospheric greenhouse effect by water vapor, to the cryosphere-albedo and to cloudiness-albedo. By 2100 the GW from the TCM is 5.1 °C for A1FI and 2.6 °C for A1T. On 2029 and including all the model forcings and feedbacks, and for those scenarios, the WR is 0.31 and 0.33 °C, respectively; by 2095, the corresponding values are ∼0.17 and ∼0.12 °C. When the warming due to vapor condensation induced by the GCR effect is excluded, for A1FI the WR increases from 0.31 to 0.53 °C by 2029, and from 0.17 to 0.29 °C by 2095; and for A1T from 0.33 to 0.65 °C by 2029, and from 0.12 to 0.23 °C by 2095. The net GW (including the WR) for both scenarios is within the range reported by the IPCC (2001). The WR is greater for the A1T on 2029, which indicates that an atmosphere with less CO 2 is more sensitive to the SA. Thus, we obtain the interesting result that the heat released in this process, masks to some degree the climate effect that these clouds have on the GW. © 2015 COSPAR. Published by Elsevier Ltd. All rights reserved."
"7003548068;16444236100;55450672000;56765484100;7004278168;56766263400;24315205000;","Climatology and changes in cloud cover in the area of the Black, Caspian, and Aral seas (1991-2010): A comparison of surface observations with satellite and reanalysis products",2016,"10.1002/joc.4435","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84938704635&doi=10.1002%2fjoc.4435&partnerID=40&md5=dda701a634eede579117be9f3576a3d3","This article presents a climatology of total cloud cover (TCC) in the area of the three inland Eurasian seas (Black, Caspian, and Aral Sea). Analyses are performed on the basis of 20 years of data (1991-2010), collected from almost 200 ground stations. Average TCC is 49%, with broad spatial and seasonal variability: minimum TCC values are found in summer and to the southeast, whereas maximum values correspond to winter and to the northwest. For the whole area, linear trend analyses show that TCC did not vary during the study period. We only detected a statistically significant positive trend (+1.2% decade-1) in autumn. We obtained different results for the regions delimited by means of a principal component analysis: a clear decrease, both for the annual, spring, and summer series, was detected for the south of Black Sea, while increasing TCC was found for the annual, autumn, and winter series in the north Caucasus and the west and north of Black Sea. We also analysed the TCC data from global gridded products, including satellite projects [International Satellite Cloud Climatology Project (ISCCP), Pathfinder Atmospheres Extended (PATMOS-x), cLoud, Albedo &amp; Radiation (CLARA)], reanalyses [ERA-interim, National Centers for Environmental Prediction/Department of Energy (NCEP/DOE), Modern-Era Retrospective Analysis for Research and Applications (MERRA)], and surface observations [Climatic Research Unit (CRU)]. Although all these products capture the seasonal evolution over the study area, they differ substantially both among them and in relation to the ground observations: reanalyses produce much lower values of TCC, while ISCCP and CLARA provide a summer minimum that is too high. Trend analyses applied to these data generally showed a decrease in TCC; only CRU and NCEP/DOE tally with the ground data as regards the absence of overall trends. These results are discussed in relation to previous studies presenting trends of other variables such as sunshine duration, diurnal temperature range, or precipitation; we also discuss the connections with changes in synoptic patterns and environmental changes, in particular in the Aral Sea region. © 2016 Royal Meteorological Society."
"56346781400;6602691453;","Weather and tourism: Thermal comfort and zoological park visitor attendance",2016,"10.3390/atmos7030044","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963944117&doi=10.3390%2fatmos7030044&partnerID=40&md5=3cdc8a5b65ab7f161d0f3887d1e3940a","Weather events have the potential to greatly impact business operations and profitability, especially in outdoor-oriented economic sectors such as Tourism, Recreation, and Leisure (TRL). Although a substantive body of work focuses on the macroscale impacts of climate change, less is known about how daily weather events influence attendance decisions, particularly relating to the physiological thermal comfort levels of each visitor. To address this imbalance, this paper focuses on ambient thermal environments and visitor behavior at the Phoenix and Atlanta zoos. Daily visitor attendances at each zoo from September 2001 to June 2011, were paired with the Physiologically Equivalent Temperature (PET) to help measure the thermal conditions most likely experienced by zoo visitors. PET was calculated using hourly atmospheric variables of temperature, humidity, wind speed, and cloud cover from 7 a.m. to 7 p.m. at each zoological park location and then classified based on thermal comfort categories established by the American Society of Heating and Air Conditioning Engineers (ASHRAE). The major findings suggested that in both Phoenix and Atlanta, optimal thermal regimes for peak attendance occurred within ""slightly warm"" and ""warm"" PET-based thermal categories. Additionally, visitors seemed to be averse to the most commonly occurring thermal extreme since visitors appeared to avoid the zoo on excessively hot days in Phoenix and excessively cold days in Atlanta. Finally, changes in the daily weather impacted visitor attendance as both zoos experienced peak attendance on days with dynamic changes in the thermal regimes and depressed attendances on days with stagnant thermal regimes. Building a better understanding of how weather events impact visitor demand can help improve our assessments of the potential impacts future climate change may have on tourism. © 2016 by the authors."
"57197651136;32668048000;25824639900;","Error assessment of satellite-derived lead fraction in the Arctic",2016,"10.5194/tc-10-585-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960947423&doi=10.5194%2ftc-10-585-2016&partnerID=40&md5=a13783e9cfb89d9b173766e581efa4ec","Leads within consolidated sea ice control heat exchange between the ocean and the atmosphere during winter, thus constituting an important climate parameter. These narrow elongated features occur when sea ice is fracturing under the action of wind and currents, reducing the local mechanical strength of the ice cover, which in turn impact the sea ice drift pattern. This creates a high demand for a high-quality lead fraction (LF) data set for sea ice model evaluation, initialization, and for the assimilation of such data in regional models. In this context, an available LF data set retrieved from satellite passive microwave observations (Advanced Microwave Scanning Radiometer - Earth Observing System, AMSR-E) is of great value, which has been providing pan-Arctic light- and cloud-independent daily coverage since 2002. In this study errors in this data set are quantified using accurate LF estimates retrieved from Synthetic Aperture Radar (SAR) images employing a threshold technique. A consistent overestimation of LF by a factor of 2-4 is found in the AMSR-E LF product. It is shown that a simple adjustment of the upper tie point used in the method to estimate the LF can reduce the pixel-wise error by a factor of 2 on average. Applying such an adjustment to the full data set may thus significantly increase the quality and value of the original data set. © 2016 Author(s)."
"36243762400;7801684147;36458602300;6603431534;19337612500;","Fingerprints of a riming event on cloud radar Doppler spectra: Observations and modeling",2016,"10.5194/acp-16-2997-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960969559&doi=10.5194%2facp-16-2997-2016&partnerID=40&md5=fc82a951a30ee0e41545a78f4dd5d7e4","Radar Doppler spectra measurements are exploited to study a riming event when precipitating ice from a seeder cloud sediment through a supercooled liquid water (SLW) layer. The focus is on the ""golden sample"" case study for this type of analysis based on observations collected during the deployment of the Atmospheric Radiation Measurement Program's (ARM) mobile facility AMF2 at Hyytiälä, Finland, during the Biogenic Aerosols - Effects on Clouds and Climate (BAECC) field campaign. The presented analysis of the height evolution of the radar Doppler spectra is a state-of-the-art retrieval with profiling cloud radars in SLW layers beyond the traditional use of spectral moments. Dynamical effects are considered by following the particle population evolution along slanted tracks that are caused by horizontal advection of the cloud under wind shear conditions. In the SLW layer, the identified liquid peak is used as an air motion tracer to correct the Doppler spectra for vertical air motion and the ice peak is used to study the radar profiles of rimed particles. A 1-D steady-state bin microphysical model is constrained using the SLW and air motion profiles and cloud top radar observations. The observed radar moment profiles of the rimed snow can be simulated reasonably well by the model, but not without making several assumptions about the ice particle concentration and the relative role of deposition and aggregation. This suggests that in situ observations of key ice properties are needed to complement the profiling radar observations before process-oriented studies can effectively evaluate ice microphysical parameterizations."
"6603684021;35182980100;14424599100;56342539300;8861664900;57170893300;7409442137;6701864422;24482676200;6506604657;55666342400;","Brown carbon aerosols from burning of boreal peatlands: Microphysical properties, emission factors, and implications for direct radiative forcing",2016,"10.5194/acp-16-3033-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960909353&doi=10.5194%2facp-16-3033-2016&partnerID=40&md5=6f63c82df3511645ea96390ead820a30","The surface air warming over the Arctic has been almost twice as much as the global average in recent decades. In this region, unprecedented amounts of smoldering peat fires have been identified as a major emission source of climate-warming agents. While much is known about greenhouse gas emissions from these fires, there is a knowledge gap on the nature of particulate emissions and their potential role in atmospheric warming. Here, we show that aerosols emitted from burning of Alaskan and Siberian peatlands are predominantly brown carbon (BrC) - a class of visible light-absorbing organic carbon (OC) - with a negligible amount of black carbon content. The mean fuel-based emission factors for OC aerosols ranged from 3.8 to 16.6 g kg-1. Their mass absorption efficiencies were in the range of 0.2-0.8 m2 g-1 at 405 nm (violet) and dropped sharply to 0.03-0.07 m2 g-1 at 532 nm (green), characterized by a mean Ångström exponent of ≈ 9. Electron microscopy images of the particles revealed their morphologies to be either single sphere or agglomerated ""tar balls"". The shortwave top-of-atmosphere aerosol radiative forcing per unit optical depth under clear-sky conditions was estimated as a function of surface albedo. Only over bright surfaces with albedo greater than 0.6, such as snow cover and low-level clouds, the emitted aerosols could result in a net warming (positive forcing) of the atmosphere. © Author(s) 2016."
"57161358100;56162305900;7003666669;7102010848;55688930000;56384704800;23095483400;57203053317;16444232500;7202079615;25031430500;7103158465;55588510300;7004214645;57163988800;57208121852;49861577800;7402803216;","On the characteristics of aerosol indirect effect based on dynamic regimes in global climate models",2016,"10.5194/acp-16-2765-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960414965&doi=10.5194%2facp-16-2765-2016&partnerID=40&md5=6b5f9028ea1d74c05cf4baaee72e5cc9","Aerosol-cloud interactions continue to constitute a major source of uncertainty for the estimate of climate radiative forcing. The variation of aerosol indirect effects (AIE) in climate models is investigated across different dynamical regimes, determined by monthly mean 500 hPa vertical pressure velocity (<i>‰</i>500), lower-tropospheric stability (LTS) and large-scale surface precipitation rate derived from several global climate models (GCMs), with a focus on liquid water path (LWP) response to cloud condensation nuclei (CCN) concentrations. The LWP sensitivity to aerosol perturbation within dynamic regimes is found to exhibit a large spread among these GCMs. It is in regimes of strong large-scale ascent (<i>‰</i>500g€¯ &lt; g€¯g'25 hPa dayg'1) and low clouds (stratocumulus and trade wind cumulus) where the models differ most. Shortwave aerosol indirect forcing is also found to differ significantly among different regimes. Shortwave aerosol indirect forcing in ascending regimes is close to that in subsidence regimes, which indicates that regimes with strong large-scale ascent are as important as stratocumulus regimes in studying AIE. It is further shown that shortwave aerosol indirect forcing over regions with high monthly large-scale surface precipitation rate (&gt; 0.1 mm dayg'1) contributes the most to the total aerosol indirect forcing (from 64 to nearly 100 %). Results show that the uncertainty in AIE is even larger within specific dynamical regimes compared to the uncertainty in its global mean values, pointing to the need to reduce the uncertainty in AIE in different dynamical regimes. © 2016 Author(s) . CC Attribution 3.0 License."
"56591585100;57206273805;22933265100;6701378450;","Understanding cirrus ice crystal number variability for different heterogeneous ice nucleation spectra",2016,"10.5194/acp-16-2611-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960172244&doi=10.5194%2facp-16-2611-2016&partnerID=40&md5=263e224dd8798de79a8cebd6a402af99","Along with minimizing parameter uncertainty, understanding the cause of temporal and spatial variability of the nucleated ice crystal number, Ni, is key to improving the representation of cirrus clouds in climate models. To this end, sensitivities of Ni to input variables like aerosol number and diameter provide valuable information about nucleation regime and efficiency for a given model formulation. Here we use the adjoint model of the adjoint of a cirrus formation parameterization (Barahona and Nenes, 2009b) to understand Ni variability for various ice-nucleating particle (INP) spectra. Inputs are generated with the Community Atmosphere Model version 5, and simulations are done with a theoretically derived spectrum, an empirical lab-based spectrum and two field-based empirical spectra that differ in the nucleation threshold for black carbon particles and in the active site density for dust. The magnitude and sign of Ni sensitivity to insoluble aerosol number can be directly linked to nucleation regime and efficiency of various INP. The lab-based spectrum calculates much higher INP efficiencies than field-based ones, which reveals a disparity in aerosol surface properties. Ni sensitivity to temperature tends to be low, due to the compensating effects of temperature on INP spectrum parameters; this low temperature sensitivity regime has been experimentally reported before but never deconstructed as done here. © Author(s) 2016."
"7101801476;7202772927;7401701196;7403577184;9249239700;7102718675;6701684534;6701845806;","Performance of the Goddard multiscale modeling framework with Goddard ice microphysical schemes",2016,"10.1002/2015MS000469","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964447040&doi=10.1002%2f2015MS000469&partnerID=40&md5=eb3b61bb458c6ce4c94662e05a8e460c","The multiscale modeling framework (MMF), which replaces traditional cloud parameterizations with cloud-resolving models (CRMs) within a host atmospheric general circulation model (GCM), has become a new approach for climate modeling. The embedded CRMs make it possible to apply CRM-based cloud microphysics directly within a GCM. However, most such schemes have never been tested in a global environment for long-term climate simulation. The benefits of using an MMF to evaluate rigorously and improve microphysics schemes are here demonstrated. Four one-moment microphysical schemes are implemented into the Goddard MMF and their results validated against three CloudSat/CALIPSO cloud ice products and other satellite data. The new four-class (cloud ice, snow, graupel, and frozen drops/hail) ice scheme produces a better overall spatial distribution of cloud ice amount, total cloud fractions, net radiation, and total cloud radiative forcing than earlier three-class ice schemes, with biases within the observational uncertainties. Sensitivity experiments are conducted to examine the impact of recently upgraded microphysical processes on global hydrometeor distributions. Five processes dominate the global distributions of cloud ice and snow amount in long-term simulations: (1) allowing for ice supersaturation in the saturation adjustment, (2) three additional correction terms in the depositional growth of cloud ice to snow, (3) accounting for cloud ice fall speeds, (4) limiting cloud ice particle size, and (5) new size-mapping schemes for snow and graupel. Despite the cloud microphysics improvements, systematic errors associated with subgrid processes, cyclic lateral boundaries in the embedded CRMs, and momentum transport remain and will require future improvement. © 2015. The Authors."
"7005528388;7102171439;6603126554;56219284300;15726427000;16645127300;8953038700;","Observation-based longwave cloud radiative kernels derived from the A-Train",2016,"10.1175/JCLI-D-15-0257.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962278687&doi=10.1175%2fJCLI-D-15-0257.1&partnerID=40&md5=f1f5d35e33e7e45e44ac84bc6445fc4b","The authors present a new method to derive both the broadband and spectral longwave observation-based cloud radiative kernels (CRKs) using cloud radiative forcing (CRF) and cloud fraction (CF) for different cloud types using multisensor A-Train observations and MERRA data collocated on the pixel scale. Both observation-based CRKs and model-based CRKs derived from the Fu-Liou radiative transfer model are shown. Good agreement between observation- and model-derived CRKs is found for optically thick clouds. For optically thin clouds, the observation-based CRKs show a larger radiative sensitivity at TOA to cloud-cover change than model-derived CRKs. Four types of possible uncertainties in the observed CRKs are investigated: 1) uncertainties in Moderate Resolution Imaging Spectroradiometer cloud properties, 2) the contributions of clear-sky changes to the CRF, 3) the assumptions regarding clear-sky thresholds in the observations, and 4) the assumption of a single-layer cloud. The observation-based CRKs show the TOA radiative sensitivity of cloud types to unit cloud fraction change as observed by the A-Train. Therefore, a combination of observation-based CRKs with cloud changes observed by these instruments over time will provide an estimate of the short-term cloud feedback by maintaining consistency between CRKs and cloud responses to climate variability. © 2016 American Meteorological Society."
"36106335800;7501627905;","Metamodeling of droplet activation for global climate models",2016,"10.1175/JAS-D-15-0223.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962217145&doi=10.1175%2fJAS-D-15-0223.1&partnerID=40&md5=bad283e8b3b920ad9034502ce354e8ac","The nucleation of cloud droplets from the ambient aerosol is a critical physical process that must be resolved for global models to faithfully predict aerosol-cloud interactions and aerosol indirect effects on climate. To better represent droplet nucleation from a complex, multimodal, and multicomponent aerosol population within the context of a global model, a new metamodeling framework is applied to derive an efficient and accurate activation parameterization. The framework applies polynomial chaos expansion to a detailed parcel model in order to derive an emulator that maps thermodynamic and aerosol parameters to the supersaturation maximum achieved in an adiabatically ascending parcel and can be used to diagnose droplet number from a single lognormal aerosol mode. The emulator requires much less computational time to build, store, and evaluate than a high-dimensional lookup table. Compared to large sample sets from the detailed parcel model, the relative error in the predicted supersaturation maximum and activated droplet number computed with the best emulator is -:6%±9:9% and 0:8%±17:8% and (one standard deviation), respectively. On average, the emulators constructed here are as accurate and between 10 and 17 times faster than a leading physically based activation parameterization. Because the underlying parcel model being emulated resolves size-dependent droplet growth factors, the emulator captures kinetic limitations on activation. The results discussed in this work suggest that this metamodeling framework can be extended to accurately account for the detailed activation of a complex aerosol population in an arbitrary coupled global aerosol-climate model. © 2016 American Meteorological Society."
"6603546080;7403180902;57208727319;8723505700;55916098100;8555710700;8669714200;","Advances in geostationary-derived longwave fluxes for the CERES synoptic (SYN1deg) product",2016,"10.1175/JTECH-D-15-0147.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962850134&doi=10.1175%2fJTECH-D-15-0147.1&partnerID=40&md5=240b7716c2466df13d19d30893ef1d28","The Clouds and the Earth's Radiant Energy System (CERES) project has provided the climate community 15 years of globally observed top-of-the-atmosphere fluxes critical for climate and cloud feedback studies. To accurately monitor the earth's radiation budget, the CERES instrument footprint fluxes must be spatially and temporally averaged properly. The CERES synoptic 1° (SYN1deg) product incorporates derived fluxes from the geostationary satellites (GEOs) to account for the regional diurnal flux variations in between Terra and Aqua CERES measurements. The Edition 4 CERES reprocessing effort has provided the opportunity to reevaluate the derivation of longwave (LW) fluxes from GEO narrowband radiances by examining the improvements from incorporating 1-hourly versus 3-hourly GEO data, additional GEO infrared (IR) channels, and multichannel GEO cloud properties. The resultant GEO LW fluxes need to be consistent across the 16-satellite climate data record. To that end, the addition of the water vapor channel, available on all GEOs, was more effective than using a reanalysis dataset's column-weighted relative humidity combined with the window channel radiance. The benefit of the CERES LW angular directional model to derive fluxes was limited by the inconsistency of the GEO cloud retrievals. Greater success was found in the direct conversion of window and water vapor channel radiances into fluxes. Incorporating 1-hourly GEO fluxes had the greatest impact on improving the accuracy of high-temporal-resolution fluxes, and normalizing the GEO LW fluxes with CERES greatly reduced the monthly regional LW flux bias. © 2016 American Meteorological Society."
"26536569500;","The Stochastic Parcel Model: A deterministic parameterization of stochastically entraining convection",2016,"10.1002/2015MS000537","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977930045&doi=10.1002%2f2015MS000537&partnerID=40&md5=fd92355f88dff9412011a67a1f4c5ced","Convective entrainment is a process that is poorly represented in existing convective parameterizations. By many estimates, convective entrainment is the leading source of error in global climate models. As a potential remedy, an Eulerian implementation of the Stochastic Parcel Model (SPM) is presented here as a convective parameterization that treats entrainment in a physically realistic and computationally efficient way. Drawing on evidence that convecting clouds comprise air parcels subject to Poisson-process entrainment events, the SPM calculates the deterministic limit of an infinite number of such parcels. For computational efficiency, the SPM groups parcels at each height by their purity, which is a measure of their total entrainment up to that height. This reduces the calculation of convective fluxes to a sequence of matrix multiplications. The SPM is implemented in a single-column model and compared with a large-eddy simulation of deep convection."
"56374581100;6701365566;56955507500;56955778100;","Changes in the type of precipitation and associated cloud types in Eastern Romania (1961-2008)",2016,"10.1016/j.atmosres.2015.10.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84946771226&doi=10.1016%2fj.atmosres.2015.10.020&partnerID=40&md5=2213815a172e2e4b9be8eca767527eb2","Recent climate change is characterized (among other things) by changes in the frequency of some meteorological phenomena. This paper deals with the long-term changes in various precipitation types, and the connection between their variability and cloud type frequencies, at 11 meteorological stations from Eastern Romania over 1961-2008. These stations were selected with respect to data record completeness for all considered variables (weather phenomena and cloud type).The meteorological variables involved in the present study are: monthly number of days with rain, snowfall, snow showers, rain and snow (sleet), sleet showers and monthly frequency of the Cumulonimbus, Nimbostratus and Stratus clouds.Our results show that all stations present statistically significant decreasing trends in the number of days with rain in the warm period of the year. Changes in the frequency of days for each precipitation type show statistically significant decreasing trends for non-convective (stratiform) precipitation - rain, drizzle, sleet and snowfall -, while the frequencies of rain shower and snow shower (convective precipitation) are increasing. Cloud types show decreasing trends for Nimbostratus and Stratus, and increasing trends for Cumulonimbus. © 2015 Elsevier B.V."
"55519994900;23991212200;56297863500;6701835010;7202208382;","Robust effects of cloud superparameterization on simulated daily rainfall intensity statistics across multiple versions of the Community Earth System Model",2016,"10.1002/2015MS000574","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956867463&doi=10.1002%2f2015MS000574&partnerID=40&md5=0baae0006f32070da89aa610729d8d09","This study evaluates several important statistics of daily rainfall based on frequency and amount distributions as simulated by a global climate model whose precipitation does not depend on convective parameterization - Super-Parameterized Community Atmosphere Model (SPCAM). Three superparameterized and conventional versions of CAM, coupled within the Community Earth System Model (CESM1 and CCSM4), are compared against two modern rainfall products (GPCP 1DD and TRMM 3B42) to discriminate robust effects of superparameterization that emerge across multiple versions. The geographic pattern of annual-mean rainfall is mostly insensitive to superparameterization, with only slight improvements in the double-ITCZ bias. However, unfolding intensity distributions reveal several improvements in the character of rainfall simulated by SPCAM. The rainfall rate that delivers the most accumulated rain (i.e., amount mode) is systematically too weak in all versions of CAM relative to TRMM 3B42 and does not improve with horizontal resolution. It is improved by superparameterization though, with higher modes in regions of tropical wave, Madden-Julian Oscillation, and monsoon activity. Superparameterization produces better representations of extreme rates compared to TRMM 3B42, without sensitivity to horizontal resolution seen in CAM. SPCAM produces more dry days over land and fewer over the ocean. Updates to CAM's low cloud parameterizations have narrowed the frequency peak of light rain, converging toward SPCAM. Poleward of 50°, where more rainfall is produced by resolved-scale processes in CAM, few differences discriminate the rainfall properties of the two models. These results are discussed in light of their implication for future rainfall changes in response to climate forcing. © 2016. The Authors."
"7004617224;7401984344;55388912500;","Comparison between total cloud cover in four reanalysis products and cloud measured by visual observations at U.S. weather stations",2016,"10.1175/JCLI-D-15-0637.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962323811&doi=10.1175%2fJCLI-D-15-0637.1&partnerID=40&md5=8b36f6cceba2b19a97baa6c4d2853105","A homogeneity-adjusted dataset of total cloud cover from weather stations in the contiguous United States is compared with cloud cover in four state-of-the-art global reanalysis products: The Climate Forecast System Reanalysis from NCEP, the Modern-Era Retrospective Analysis for Research and Applications from NASA, ERA-Interim from ECMWF, and the Japanese 55-year Reanalysis Project from the Japan Meteorological Agency. The reanalysis products examined in this study generally show much lower cloud amount than visual weather station data, and this underestimation appears to be generally consistent with their overestimation of downward surface shortwave fluxes when compared with surface radiation data from the Surface Radiation Network. Nevertheless, the reanalysis products largely succeed in simulating the main aspects of interannual variability of cloudiness for large-scale means, as measured by correlations of 0.81-0.90 for U.S. mean time series. Trends in the reanalysis datasets for the U.S. mean for 1979-2009, ranging from -0.38% to -1.8% decade-1, are in the same direction as the trend in surface data (-0.50% decade-1), but further effort is needed to understand the discrepancies in their magnitudes. © 2016 American Meteorological Society."
"55918310000;36604588400;35758381900;55918993800;","Comparison of four machine learning algorithms for their applicability in satellite-based optical rainfall retrievals",2016,"10.1016/j.atmosres.2015.09.021","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84954105449&doi=10.1016%2fj.atmosres.2015.09.021&partnerID=40&md5=3737f991049618246525fde63262558a","Machine learning (ML) algorithms have successfully been demonstrated to be valuable tools in satellite-based rainfall retrievals which show the practicability of using ML algorithms when faced with high dimensional and complex data. Moreover, recent developments in parallel computing with ML present new possibilities for training and prediction speed and therefore make their usage in real-time systems feasible. This study compares four ML algorithms - random forests (RF), neural networks (NNET), averaged neural networks (AVNNET) and support vector machines (SVM) - for rainfall area detection and rainfall rate assignment using MSG SEVIRI data over Germany. Satellite-based proxies for cloud top height, cloud top temperature, cloud phase and cloud water path serve as predictor variables. The results indicate an overestimation of rainfall area delineation regardless of the ML algorithm (averaged bias=1.8) but a high probability of detection ranging from 81% (SVM) to 85% (NNET). On a 24-hour basis, the performance of the rainfall rate assignment yielded R2 values between 0.39 (SVM) and 0.44 (AVNNET). Though the differences in the algorithms' performance were rather small, NNET and AVNNET were identified as the most suitable algorithms. On average, they demonstrated the best performance in rainfall area delineation as well as in rainfall rate assignment. NNET's computational speed is an additional advantage in work with large datasets such as in remote sensing based rainfall retrievals. However, since no single algorithm performed considerably better than the others we conclude that further research in providing suitable predictors for rainfall is of greater necessity than an optimization through the choice of the ML algorithm. © 2015 Elsevier B.V."
"57202591780;20336852100;7003581627;57195563259;7007038975;7005207565;42761134600;56029500900;36720718800;6506742284;57205761224;7202747495;57209136831;6603640566;7004804042;8282941300;57209139739;56680128900;","The land‐potential knowledge system (landpks): mobile apps and collaboration for optimizing climate change investments",2016,"10.1002/ehs2.1209","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996488841&doi=10.1002%2fehs2.1209&partnerID=40&md5=7cc0a119c7405099d18e7bbeb9ccaedb","Massive investments in climate change mitigation and adaptation are projected during coming decades. Many of these investments will seek to modify how land is managed. The return on both types of investments can be increased through an understanding of land potential: the potential of the land to support primary production and ecosystem services, and its resilience. A Land‐Potential Knowledge System (LandPKS) is being developed and implemented to provide individual users with point‐based estimates of land potential based on the integration of simple, geo‐tagged user inputs with cloud‐based information and knowledge. This system will rely on mobile phones for knowledge and information exchange, and use cloud computing to integrate, interpret, and access relevant knowledge and information, including local knowledge about land with similar potential. The system will initially provide management options based on long‐term land potential, which depends on climate, topography, and relatively static soil properties, such as soil texture, depth, and mineralogy. Future modules will provide more specific management information based on the status of relatively dynamic soil properties such as organic matter and nutrient content, and of weather. The paper includes a discussion of how this system can be used to help distinguish between meteorological and edaphic drought. © 2016, © 2016 Herrick et al."
"7202803069;55619429300;","Dust aerosol emission over the Sahara during summertime from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations",2016,"10.1016/j.atmosenv.2015.12.037","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84953791458&doi=10.1016%2fj.atmosenv.2015.12.037&partnerID=40&md5=8b8770a0359942c54a539afba3c64f4b","Dust aerosols are an important component of the climate system and a challenge to incorporate into weather and climate models. Information on the location and magnitude of dust emission remains a key information gap to inform model development. Inadequate surface observations ensure that satellite data remain the primary source of this information over extensive and remote desert regions. Here, we develop estimates of the relative magnitude of active dust emission over the Sahara desert based on data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Utilising the unique vertical profile of aerosol characteristics provided by CALIOP our algorithm identifies emission from aerosol extinction and lidar backscatter in the near surface layers. From the long-term CALIOP archive of day and night-time orbits over 2006-13 we construct coarse resolution maps of a new dust emission index (DEI) for the Sahara desert during the peak summer dust season (June to September). The spatial structure of DEI indicates highest emission over a broad zone focused on the border regions of Southern Algeria, Northern Mali and northwest Niger, displaced substantially (~7°) to the east of the mean maximum in satellite-derived aerosol optical depth. In this region night-time emission exceeds that during the day. The DEI maps substantially corroborate recently derived dust source frequency count maps based on back-tracking plumes in high temporal resolution SEVIRI imagery. As such, a convergence of evidence from multiple satellite data sources using independent methods provides an increasingly robust picture of Saharan dust emission sources. Various caveats are considered. As such, quantitative estimates of dust emission may require a synergistic combined multi-sensor analysis. © 2015."
"8688004400;6603263640;7004978125;57193882808;","Multiscale interactions in an idealized walker cell: Analysis with isentropic streamfunctions",2016,"10.1175/JAS-D-15-0070.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962214158&doi=10.1175%2fJAS-D-15-0070.1&partnerID=40&md5=435e8c0cd9e6afdb6d153b173bf65e44","A new approach for analyzing multiscale properties of the atmospheric flow is proposed in this study. For that, the recently introduced isentropic streamfunctions are employed here for scale decomposition with Haar wavelets. This method is applied subsequently to a cloud-resolving simulation of a planetary Walker cell characterized by pronounced multiscale flow. The resulting set of isentropic streamfunctions-obtained at the convective, meso-, synoptic, and planetary scales-capture many important features of the across-scale interactions within an idealized Walker circulation. The convective scale is associated with the shallow, congestus, and deep clouds, which jointly dominate the upward mass flux in the lower troposphere. The synoptic and planetary scales play important roles in extending mass transport to the upper troposphere, where the corresponding streamfunctions mainly capture the first baroclinic mode associated with large-scale overturning circulation. The intermediate-scale features of the flow, such as anvil clouds associated with organized convective systems, are extracted with the mesoscale and synoptic-scale isentropic streamfunctions. Multiscale isentropic streamfunctions are also used to extract salient mechanisms that underlie the low-frequency variability of the Walker cell. In particular, the lag of a few days of the planetary scale behind the convective scale indicates the importance of the convective scale in moistening the atmosphere and strengthening the planetary-scale overturning circulation. Furthermore, the mesoscale and synoptic scale lags behind the planetary scale reflect the strong dependence of convective organization on the background shear. © 2016 American Meteorological Society."
"35237179700;36241005100;22134910200;38863214100;7006432040;6602412939;36638394000;7102521078;","THE INNER EDGE of the HABITABLE ZONE for SYNCHRONOUSLY ROTATING PLANETS AROUND LOW-MASS STARS USING GENERAL CIRCULATION MODELS",2016,"10.3847/0004-637X/819/1/84","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960969279&doi=10.3847%2f0004-637X%2f819%2f1%2f84&partnerID=40&md5=e1d4e0d1f4709c1a485ac93188f41e9a","Terrestrial planets at the inner edge of the habitable zone (HZ) of late-K and M-dwarf stars are expected to be in synchronous rotation, as a consequence of strong tidal interactions with their host stars. Previous global climate model (GCM) studies have shown that, for slowly rotating planets, strong convection at the substellar point can create optically thick water clouds, increasing the planetary albedo, and thus stabilizing the climate against a thermal runaway. However these studies did not use self-consistent orbital/rotational periods for synchronously rotating planets placed at different distances from the host star. Here we provide new estimates of the inner edge of the HZ for synchronously rotating terrestrial planets around late-K and M-dwarf stars using a 3D Earth-analog GCM with self-consistent relationships between stellar metallicity, stellar effective temperature, and the planetary orbital/rotational period. We find that both atmospheric dynamics and the efficacy of the substellar cloud deck are sensitive to the precise rotation rate of the planet. Around mid-to-late M-dwarf stars with low metallicity, planetary rotation rates at the inner edge of the HZ become faster, and the inner edge of the HZ is farther away from the host stars than in previous GCM studies. For an Earth-sized planet, the dynamical regime of the substellar clouds begins to transition as the rotation rate approaches ∼10 days. These faster rotation rates produce stronger zonal winds that encircle the planet and smear the substellar clouds around it, lowering the planetary albedo, and causing the onset of the water-vapor greenhouse climatic instability to occur at up to ∼25% lower incident stellar fluxes than found in previous GCM studies. For mid-to-late M-dwarf stars with high metallicity and for mid-K to early-M stars, we agree with previous studies. © 2016. The American Astronomical Society. All rights reserved.."
"15060156600;56012359800;56439080000;","Clues that decaying leaves enrich Arctic air with ice nucleating particles",2016,"10.1016/j.atmosenv.2016.01.027","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957921493&doi=10.1016%2fj.atmosenv.2016.01.027&partnerID=40&md5=5f30f2761cddffb9ff3b4b3963f844be","Decaying leaves from Arctic regions have previously been reported to produce large numbers of ice nucleating particles (IN). Their atmospheric relevance is unclear. Our initial observations at a coastal mountain observatory in northern Norway reveal a tripling in concentrations of IN active at -15 °C (IN-15) in oceanic air after about one day of passage over land (from 1.7 and 4.9 IN-15 m-3, to 9.6 and 12.2 IN-15 m-3). Analysis of leaf litter collected near the observatory supports the earlier report of numerous IN associated with leaf litter on the ground (2 (dot operator) 102 IN-15 μg-1 litter particles &lt; 5 μm). Together, both findings suggest that decaying leaves are a strong emission source of IN to the Arctic boundary layer. © 2016 The Authors."
"6507952920;36000595000;7801565183;7102346729;7202485447;","Overview of the special issue “selected papers from the 2nd atmospheric chemistry and physics at mountain sites Symposium”",2016,"10.4209/aaqr.2016.02.0077","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959363265&doi=10.4209%2faaqr.2016.02.0077&partnerID=40&md5=32069be6f12ad8304840fa375d02bcfe","Mountain sites provide a unique window on atmospheric chemistry and physics. These sites allow for continuous observations at high elevation, often in the free troposphere, where many important processes occur. Observations at these mountain sites allow for studies on long-range transport of pollution, cloud and precipitation processes, boundary layer ventilation and long-term observations of climate relevant gases and aerosols. However operating at mountain sites presents a unique set of challenges, and for this reason scientists doing research at these sites sought a forum to share knowledge on both the science and challenges of working at these sites. © Taiwan Association for Aerosol Research."
"7103000184;26424509000;7202948585;56914807500;57148154300;57146708400;7004095525;6701659248;57155075700;6603344318;16416454400;","Atmospheric Chemistry measurements at Whiteface Mountain, NY: Cloud water chemistry, precipitation chemistry, and particulate matter",2016,"10.4209/aaqr.2015.05.0344","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959335473&doi=10.4209%2faaqr.2015.05.0344&partnerID=40&md5=f00aa66a39adb7f88e6781fe0f6476bf","Long-term records of condensed-phase chemical data are presented from the Adirondack Mountain region of northern New York, USA. These data records are particularly valuable due to the combinations of aerosol, cloud, and precipitation measurements. Objectives of the research and this overview paper include the evaluation of emission reductions of regulated air pollutants and the observed effects on measured deposition, as well as the implications of changing pollutant concentration levels on human health and climate. Summer season cloud chemistry and year-round wet deposition and particulate matter data from two stations on Whiteface Mountain are presented to highlight some of the research and monitoring activities at this mountain location. Clear decreases in the anion concentrations and increases in pH over the past two decades have been observed in cloud and precipitation results. Large decreases in aerosol sulfate (&gt; 80%) and aerosol optical black carbon (&gt; 60%) have been observed for these species over the nearly 40 year summit observatory data record for these measurements, and decreases in PM2.5 mass, sulfate, nitrate, and ammonium have also been recorded over the shorter 15 year period of measurement at the Marble Mountain Lodge level. The studies cited here highlight some of the past successes of air pollution regulation under the Clean Air Act and Amendments and pave the way for future progress in reducing air pollution. © Taiwan Association for Aerosol Research."
"56915127000;7202516876;55258950300;7403079681;","The roles of convective and stratiform precipitation in the observed precipitation trends in Northwest China during 1961-2000",2016,"10.1016/j.atmosres.2015.10.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84944909492&doi=10.1016%2fj.atmosres.2015.10.001&partnerID=40&md5=503f966bdc402210cc62924a3ddd35b3","Northwest China is one of the most arid areas in East Asia. Previous studies pointed out that some regions of Northwest China experienced a dry to wet climate change in the past half century. This study analyzed the observed daily precipitation during 1961-2000 in Northwest China. Results show that the annual precipitation in Northwest China has different trends in the western region and the eastern region. The western region has a significant increasing trend as shown in previous studies, while the eastern region has a decreasing trend. It is found that the increasing trend in the western region is caused by the increase of the heaviest precipitation in summer, while the decreasing trend in the eastern region is caused by the decrease of the heaviest precipitation in autumn. In order to find out the dominating precipitation type in the change of precipitation, a simple parameter is used to distinguish convective precipitation from stratiform precipitation. It is found that the increase of the heaviest precipitation in summer in the western region resulted from the increased frequency of convective precipitation, and the decrease of the heaviest precipitation in autumn in the eastern region was caused by the decreased frequency of stratiform precipitation. © 2015 Elsevier B.V."
"56800676100;16244996700;57096629100;57204549544;","Influence of aerosols on atmospheric variables in the HARMONIE model",2016,"10.1016/j.atmosres.2015.08.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84954398952&doi=10.1016%2fj.atmosres.2015.08.001&partnerID=40&md5=b33dd33f1752034d6cf85edd18fa5f0a","The mesoscale HARMONIE model is used to investigate the potential influence of aerosols on weather forecasts, and in particular, on precipitation. The study considers three numerical experiments over the Atlantic-Europe-Northern Africa region during 11-16 August 2010 with the following configurations: (a) no aerosols, (b) only the sea aerosols, and (c) the four types of the aerosols: sea, land, organic, and dust aerosols. The spatio-temporal analysis of forecast differences highlights the impact of aerosols on the prediction of main meteorological variables such as air temperature, humidity, precipitation, and cloud cover as well as their vertical profiles. The variations occur through changes in radiation fluxes and microphysics properties. The sensitivity experiments with the inclusion of climatological aerosol concentrations demonstrate the importance of aerosol effects on weather prediction. © 2015 Elsevier B.V."
"6602738250;35491881700;6701348241;","Representativeness errors in comparing chemistry transport and chemistry climate models with satellite UV-Vis tropospheric column retrievals",2016,"10.5194/gmd-9-875-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959530996&doi=10.5194%2fgmd-9-875-2016&partnerID=40&md5=08603f44a888135bea3cd07eac332365","Ultraviolet-visible (UV-Vis) satellite retrievals of trace gas columns of nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) are useful to test and improve models of atmospheric composition, for data assimilation, air quality hindcasting and forecasting, and to provide top-down constraints on emissions. However, because models and satellite measurements do not represent the exact same geophysical quantities, the process of confronting model fields with satellite measurements is complicated by representativeness errors, which degrade the quality of the comparison beyond contributions from modelling and measurement errors alone. Here we discuss three types of representativeness errors that arise from the act of carrying out a model-satellite comparison: (1) horizontal representativeness errors due to imperfect collocation of the model grid cell and an ensemble of satellite pixels called superobservation, (2) temporal representativeness errors originating mostly from differences in cloud cover between the modelled and observed state, and (3) vertical representativeness errors because of reduced satellite sensitivity towards the surface accompanied with necessary retrieval assumptions on the state of the atmosphere. To minimize the impact of these representativeness errors, we recommend that models and satellite measurements be sampled as consistently as possible, and our paper provides a number of recipes to do so. A practical confrontation of tropospheric NO2 columns simulated by the TM5 chemistry transport model (CTM) with Ozone Monitoring Instrument (OMI) tropospheric NO2 retrievals suggests that horizontal representativeness errors, while unavoidable, are limited to within 5-10 % in most cases and of random nature. These errors should be included along with the individual retrieval errors in the overall superobservation error. Temporal sampling errors from mismatches in cloud cover, and, consequently, in photolysis rates, are of the order of 10 % for NO2 and HCHO, and systematic, but partly avoidable. In the case of air pollution applications where sensitivity down to the ground is required, we recommend that models should be sampled on the same mostly cloud-free days as the satellite retrievals. The most relevant representativeness error is associated with the vertical sensitivity of UV-Vis satellite retrievals. Simple vertical integration of modelled profiles leads to systematically different model columns compared to application of the appropriate averaging kernel. In comparing OMI NO2 to GEOS-Chem NO2 simulations, these systematic differences are as large as 15-20 % in summer, but, again, avoidable. © 2016 Author(s)."
"56177641200;57159076600;47962425400;56405556000;36767852000;7003897194;7403253796;7404865816;","Hygroscopic Characteristics of Alkylaminium Carboxylate Aerosols",2016,"10.1021/acs.est.5b04691","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960192643&doi=10.1021%2facs.est.5b04691&partnerID=40&md5=452a1e1a8b34b0fed0e4a46d40b111bb","The hygroscopic growth factor (HGF) and cloud condensation nuclei (CCN) activity for a series of alkylaminium carboxylate aerosols have been measured using a hygroscopicity tandem differential mobility analyzer coupled to a condensation particle counter and a CCN counter. The particles, consisting of the mixtures of mono- (acetic, propanoic, p-toluic, and cis-pinonic acid) and dicarboxylic (oxalic, succinic, malic, adipic, and azelaic acid) acid with alkylamine (mono-, di-, and trimethylamines), represent those commonly found under diverse environmental conditions. The hygroscopicity parameter (κ) of the alkylaminium carboxylate aerosols was derived from the HGF and CCN results and theoretically calculated. The HGF at 90% RH is in the range of 1.3 to 1.8 for alkylaminium monocarboxylates and 1.1 to 2.2 for alkylaminium dicarboxylates, dependent on the molecular functionality (i.e., the carboxylic or OH functional group in organic acids and methyl substitution in alkylamines). The κ value for all alkylaminium carboxylates is in the range of 0.06-1.37 derived from the HGF measurements at 90% RH, 0.05-0.49 derived from the CCN measurements, and 0.22-0.66 theoretically calculated. The measured hygroscopicity of the alkylaminium carboxylates increases with decreasing acid to base ratio. The deliquescence point is apparent for several of the alkylaminium dicarboxylates but not for the alkylaminium monocarboxylates. Our results reveal that alkylaminium carboxylate aerosols exhibit distinct hygroscopic and deliquescent characteristics that are dependent on their molecular functionality, hence regulating their impacts on human health, air quality, and direct and indirect radiative forcing on climate. © 2016 American Chemical Society."
"6507223114;12902598300;","Variation of reference evapotranspiration in the central region of Argentina between 1941 and 2010",2016,"10.1016/j.ejrh.2015.11.009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949449310&doi=10.1016%2fj.ejrh.2015.11.009&partnerID=40&md5=d5cd152d18866c8f36826761bb5e7d54","Study region: Changes in reference evapotranspiration (ETo) may have important consequences for agricultural suitability in the central region of Argentina. Annual ETo variation was assessed, in terms of both territory and time, for the 7 decades between 1941 and 2010, analyzing the behavior of the 4 atmospheric variables which determine it: temperature, vapor pressure, wind speed and cloud cover. Study focus: The influence of each variable on ETo was evaluated from a multiple regression model and a simple correlation analysis, using climate data from the observation network, and repeating this analysis using interpolated variables. In this grid scheme, linear relationships were determined between ETo and the different key atmospheric variables, plus precipitation (PP), and the t test was applied to establish the statistically significant sectors (P&lt;0.1). Then, those areas with a significant trend change (P&lt;0.1) were determined by the Mann-Kendall test. Finally, the interception of the grids was performed to establish their joint occurrence. New hydrological insights for the region: Most of the region analyzed (&gt;91%) presents a non-significant variation of ETo over time, with a mostly non-significant change of each driving variable, regarding both its relationship with ETo and its own trend of change. The beneficial change in agricultural suitability reported for this water-limited region was found to be produced almost exclusively by increasing PP. © 2015 The Authors."
"36020828900;12762440500;7202535445;25959487500;29367493100;","Climatology of lightning activity in South China and its relationships to precipitation and convective available potential energy",2016,"10.1007/s00376-015-5124-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84953439331&doi=10.1007%2fs00376-015-5124-5&partnerID=40&md5=e2853e52843b9fa6d07626815f0fa686","This study examined lightning activity and its relationship to precipitation and convective available potential energy (CAPE) in South China during 2001–12, based on data from the Guangdong Lightning Location System, the Tropical Rainfall Measuring Mission satellite, and the ERA-Interim dataset. Two areas of high lightning density are identified: one over the Pearl River Delta, and the other to the north of Leizhou Peninsula. Large peak-current cloud-to-ground (LPCCG) lightning (&gt;75 kA) shows weaker land–offshore contrasts than total CG lightning, in which negative cloud-to-ground (NCG) lightning occurs more prominently than positive cloud-to-ground (PCG) lightning on land. While the frequency of total CG lightning shows a main peak in June and a second peak in August, the LPCCG lightning over land shows only a single peak in June. The ratio of positive LPCCG to total lightning is significantly greater during February–April than during other times of the year. Diurnally, CG lightning over land shows only one peak in the afternoon, whereas CG lightning offshore shows morning and afternoon peaks. The rain yield per flash is on the order of 107–108 kg per flash across the analysis region, and its spatial distribution is opposite to that of lightning density. Our data show that lightning activity over land is more sensitive than that over offshore waters to CAPE. The relationships between lightning activity and both precipitation and CAPE are associated with convection activity in the analysis region. © 2016, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg."
"56386413300;56102226900;7103156757;55568336800;56386630400;55568469800;55568482500;","The diversity and role of bacterial ice nuclei in rainwater from mountain sites in China",2016,"10.4209/aaqr.2015.05.0315","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959349894&doi=10.4209%2faaqr.2015.05.0315&partnerID=40&md5=f8b79bdbc9c5334cb8aaad4753f112b9","Ice nuclei (IN) that catalyze ice nucleation in the atmosphere are considered to be vital to the initiation of ice formation in clouds, which in turn impact precipitation and climate. Some bacterial ice-nucleating particles are presumed to speed up ice formation at relatively warm temperatures (above -10°C), and may thus contribute to the induction of precipitation. In this study, nine rainwater samples were collected from forest ecosystems located in the Changbai, Wuling, and Dinghu mountains in eastern China, and the microbial community compositions were determined. Species of the genus Pseudomonas are considered to be the most efficient ice nucleation-active bacteria; however, Pseudomonas spp. were only observed in two of the rainwater samples from two months (June and September) at the Wuling Mountain site (2% of total Sanger clones sets). The median freezing temperature (T50) of crude rain droplets ranged from -11.2°C to -18.6°C based on immersion-mode freezing experiments, and their cumulative IN spectrum revealed a very low or near-zero frequency of bacterial IN at -10°C, which was used as the temperature cutoff to define ice nucleators of biological origin. The T50 of the filtrate (&lt; 0.22 µm) was between -16.0°C and -20.8°C. The frequency of IN was higher at -10°C from the particle (≥ 0.22 µm) suspension of rainwater collected in 2013, with an onset freezing temperature of approximately -6°C or warmer, and a T50 value from -8.2 to -14.0°C. Moreover, ice nucleation was significantly deactivated by heat treatment (to disrupt the structure of membrane-bound proteins) at -10°C, with an average inhibition of 85%. Our results indicate that bacterial IN are present but play a minor role in ice nucleation. Further studies evaluating the concentration and physical chemistry of bacteria in the atmosphere are needed to confirm these results. © Taiwan Association for Aerosol Research."
"7103180783;7402401574;6602080205;53880473700;","Preferred response of the East Asian summer monsoon to local and non-local anthropogenic sulphur dioxide emissions",2016,"10.1007/s00382-015-2671-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959113205&doi=10.1007%2fs00382-015-2671-5&partnerID=40&md5=6db0e8ae1c59616de9278aa629883383","In this study, the atmospheric component of a state-of-the-art climate model (HadGEM2-ES) that includes earth system components such as interactive chemistry and eight species of tropospheric aerosols considering aerosol direct, indirect, and semi-direct effects, has been used to investigate the impacts of local and non-local emissions of anthropogenic sulphur dioxide on the East Asian summer monsoon (EASM). The study focuses on the fast responses (including land surface feedbacks, but without sea surface temperature feedbacks) to sudden changes in emissions from Asia and Europe. The initial responses, over days 1–40, to Asian and European emissions show large differences. The response to Asian emissions involves a direct impact on the sulphate burden over Asia, with immediate consequences for the shortwave energy budget through aerosol–radiation and aerosol–cloud interactions. These changes lead to cooling of East Asia and a weakening of the EASM. In contrast, European emissions have no significant impact on the sulphate burden over Asia, but they induce mid-tropospheric cooling and drying over the European sector. Subsequently, however, this cold and dry anomaly is advected into Asia, where it induces atmospheric and surface feedbacks over Asia and the Western North Pacific (WNP), which also weaken the EASM. In spite of very different perturbations to the local aerosol burden in response to Asian and European sulphur dioxide emissions, the large scale pattern of changes in land–sea thermal contrast, atmospheric circulation and local precipitation over East Asia from days 40 onward exhibits similar structures, indicating a preferred response, and suggesting that emissions from both regions likely contributed to the observed weakening of the EASM. Cooling and drying of the troposphere over Asia, together with warming and moistening over the WNP, reduces the land–sea thermal contrast between the Asian continent and surrounding oceans. This leads to high sea level pressure (SLP) anomalies over Asia and low SLP anomalies over the WNP, associated with a weakened EASM. In response to emissions from both regions warming and moistening over the WNP plays an important role and determines the time scale of the response. © 2015, The Author(s)."
"57192087588;7004326151;","Annual dynamics of impervious surface in the Pearl River Delta, China, from 1988 to 2013, using time series Landsat imagery",2016,"10.1016/j.isprsjprs.2016.01.003","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84954466401&doi=10.1016%2fj.isprsjprs.2016.01.003&partnerID=40&md5=741d91e1b892d2ec7e4cd9109b827e39","Information on impervious surface distribution and dynamics is useful for understanding urbanization and its impacts on hydrological cycle, water management, surface energy balances, urban heat island, and biodiversity. Numerous methods have been developed and successfully applied to estimate impervious surfaces. Previous methods of impervious surface estimation mainly focused on the spectral differences between impervious surfaces and other land covers. Moreover, the accuracy of estimation from single or multi-temporal images was often limited by the mixed pixel problem in coarse- or medium-resolution imagery or by the intra-class spectral variability problem in high resolution imagery. Time series satellite imagery provides potential to resolve the above problems as well as the spectral confusion with similar surface characteristics due to phenological change, inter-annual climatic variability, and long-term changes of vegetation. Since Landsat time series has a long record with an effective spatial resolution, this study aimed at estimating and mapping impervious surfaces by analyzing temporal spectral differences between impervious and pervious surfaces that were extracted from dense time series Landsat imagery. Specifically, this study developed an efficient method to extract annual impervious surfaces from time series Landsat data and applied it to the Pearl River Delta, southern China, from 1988 to 2013. The annual classification accuracy yielded from 71% to 91% for all classes, while the mapping accuracy of impervious surfaces ranged from 80.5% to 94.5%. Furthermore, it is found that the use of more than 50% of Scan Line Corrector (SLC)-off images after 2003 did not substantially reduced annual classification accuracy, which ranged from 78% to 91%. It is also worthy to note that more than 80% of classification accuracies were achieved in both 2002 and 2010 despite of more than 40% of cloud cover detected in these two years. These results suggested that the proposed method was effective and efficient in mapping impervious surfaces and detecting impervious surface changes by using temporal spectral differences from dense time series Landsat imagery. The value of full sampling was revealed for enhancing temporal resolution and identifying temporal differences between impervious and pervious surfaces in time series analysis. © 2016 International Society for Photogrammetry and Remote Sensing, Inc. (ISPRS)."
"35423527600;57145509400;56502000100;7005280212;57147801600;40461229800;26639062900;","Transported mineral dust deposition case study at a hydrologically sensitive mountain site: Size and composition shifts in ambient aerosol and snowpack",2016,"10.4209/aaqr.2015.05.0346","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959351961&doi=10.4209%2faaqr.2015.05.0346&partnerID=40&md5=bf9f13a46a644fa3843a39e2e8ce4aa9","Transported mineral dust deposition to remote mountain snow decreases snow albedo and increases absorption of solar radiation, which accelerates snowpack melt and alters water supply. Mineralogy and chemical composition determine dust particle optical properties, which vary by source region. While impacts of dust deposition at remote mountain sites have been established, few studies have connected the chemical composition of ambient particles during deposition events with the properties of those deposited on the snowpack. Ambient particles and surface snow were sampled in the San Juan Mountains of southwestern Colorado, which frequently experiences dust deposition in the spring and has evidence of dust- enhanced snow melt. Individual particles were analyzed using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). The number concentration and size distribution of insoluble residues in the top level of snow were determined with nanoparticle tracking analysis (NTA). During a minor dust event (April 2-3, 2015), the fraction of absorbing iron-enriched dust in the ambient aerosol, the number concentration, and size of insoluble residues in snow all increased. This can be traced to shifts in mineral dust source region within the Colorado Plateau, during which, there were higher wind speeds leading to increased transport. The shift in chemical composition and mineralogy of the transported dust has the potential to impact snowpack radiative forcing during dry deposition. In addition, it can also modify the snowpack through scavenging of particles during wet deposition, as well as alter the properties of clouds and orographic precipitation. Understanding these impacts is crucial to understanding the hydrological cycle at remote mountain sites. © Taiwan Association for Aerosol Research."
"55635193600;56111334000;56879858000;6701458964;8291099000;55075942300;7003602972;57044071100;13103184200;7003461830;35774441900;53980757300;7003854090;6603545563;","Observations of atmospheric monoaromatic hydrocarbons at urban, semi-urban and forest environments in the Amazon region",2016,"10.1016/j.atmosenv.2015.12.053","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84953776231&doi=10.1016%2fj.atmosenv.2015.12.053&partnerID=40&md5=d47569443a67c18adadc53e1783c8546","The Amazon region is one of the most significant natural ecosystems on the planet. Of special interest as a major study area is the interface between the forest and Manaus city, a state capital in Brazil embedded in the heart of the Amazon forest. In view of the interactions between natural and anthropogenic processes, an integrated experiment was conducted measuring the concentrations of the volatile organic compounds (VOCs) benzene, toluene, ethylbenzene and meta, ortho, para-xylene (known as BTEX), all of them regarded as pollutants with harmful effects on human health and vegetation and acting also as important precursors of tropospheric ozone. Furthermore, these compounds also take part in the formation of secondary organic aerosols, which can influence the pattern of cloud formation, and thus the regional water cycle and climate. The samples were collected in 2012/2013 at three different sites: (i) The Amazon Tall Tower Observatory (ATTO), a pristine rain forest region in the central Amazon Basin; (ii) Manacapuru, a semi-urban site located southwest and downwind of Manaus as a preview of the Green Ocean Amazon Experiment (GoAmazon 2014/15); and (iii) the city of Manaus (distributed over three sites). Results indicate that there is an increase in pollutant concentrations with increasing proximity to urban areas. For instance, the benzene concentration ranges were 0.237-19.6 (Manaus), 0.036-0.948 (Manacapuru) and 0.018-0.313 μg m-3 (ATTO). Toluene ranges were 0.700-832 (Manaus), 0.091-2.75 μg m-3 (Manacapuru) and 0.011-4.93 (ATTO). For ethylbenzene, they were 0.165-447 (Manaus), 0.018-1.20 μg m-3 (Manacapuru) and 0.047-0.401 (ATTO). Some indication was found for toluene to be released from the forest. No significant difference was found between the BTEX levels measured in the dry season and the wet seasons. Furthermore, it was observed that, in general, the city of Manaus seems to be less impacted by these pollutants than other cities in Brazil and in other countries, near the coastline or on the continent. A risk analysis for the health of Manaus' population was performed and indicated that the measured concentrations posed a risk for development of chronic diseases and cancer for the population of Manaus. © 2015 Elsevier Ltd."
"42462407100;7004587644;55951225700;55777759900;56261301800;35775264900;7006441949;","Evaluation of the ACCESS - Chemistry-climate model for the Southern Hemisphere",2016,"10.5194/acp-16-2401-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959543431&doi=10.5194%2facp-16-2401-2016&partnerID=40&md5=4438c1b8e7d15581de8920d0bec3dfdc","Chemistry-climate models are important tools for addressing interactions of composition and climate in the Earth system. In particular, they are used to assess the combined roles of greenhouse gases and ozone in Southern Hemisphere climate and weather. Here we present an evaluation of the Australian Community Climate and Earth System Simulator - chemistry-climate model (ACCESS-CCM), focusing on the Southern Hemisphere and the Australian region. This model is used for the Australian contribution to the international Chemistry-Climate Model Initiative, which is soliciting hindcast, future projection and sensitivity simulations. The model simulates global total column ozone (TCO) distributions accurately, with a slight delay in the onset and recovery of springtime Antarctic ozone depletion, and consistently higher ozone values. However, October-averaged Antarctic TCO from 1960 to 2010 shows a similar amount of depletion compared to observations. Comparison with model precursors shows large improvements in the representation of the Southern Hemisphere stratosphere, especially in TCO concentrations. A significant innovation is seen in the evaluation of simulated vertical profiles of ozone and temperature with ozonesonde data from Australia, New Zealand and Antarctica from 38 to 90° S. Excess ozone concentrations (greater than 26 % at Davis and the South Pole during winter) and stratospheric cold biases (up to 10 K at the South Pole during summer and autumn) outside the period of perturbed springtime ozone depletion are seen during all seasons compared to ozonesondes. A disparity in the vertical location of ozone depletion is seen: centred around 100 hPa in ozonesonde data compared to above 50 hPa in the model. Analysis of vertical chlorine monoxide profiles indicates that colder Antarctic stratospheric temperatures (possibly due to reduced mid-latitude heat flux) are artificially enhancing polar stratospheric cloud formation at high altitudes. The model's inability to explicitly simulate a supercooled ternary solution may also explain the lack of depletion at lower altitudes. Analysis of the simulated Southern Annular Mode (SAM) index compares well with ERA-Interim data, an important metric for correct representation of Australian climate. Accompanying these modulations of the SAM, 50 hPa zonal wind differences between 2001-2010 and 1979-1998 show increasing zonal wind strength southward of 60° S during December for both the model simulations and ERA-Interim data. These model diagnostics show that the model reasonably captures the stratospheric ozone-driven chemistry-climate interactions important for Australian climate and weather while highlighting areas for future model development. © Author(s) 2016."
"57142867400;56611366900;55745955800;19638935200;","New understanding and quantification of the regime dependence of aerosol-cloud interaction for studying aerosol indirect effects",2016,"10.1002/2016GL067683","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977829941&doi=10.1002%2f2016GL067683&partnerID=40&md5=ab902e1fac84fff7ef2f1ffe5f6573c3","Aerosol indirect effects suffer from large uncertainty in climate models and among observations. This study focuses on two plausible factors: regime dependence of aerosol-cloud interactions and the effect of cloud droplet spectral shape. We show, using a new parcel model, that combined consideration of droplet number concentration (Nc) and relative dispersion (ε, ratio of standard deviation to mean radius of the cloud droplet size distribution) better characterizes the regime dependence of aerosol-cloud interactions than considering Nc alone. Given updraft velocity (w), ε increases with increasing aerosol number concentration (Na) in the aerosol-limited regime, peaks in the transitional regime, and decreases with further increasing Na in the updraft-limited regime. This new finding further reconciles contrasting observations in literature and reinforces the compensating role of dispersion effect. The nonmonotonic behavior of ε further quantifies the relationship between the transitional Na and w that separates the aerosol- and updraft-limited regimes. ©2016. The Authors."
"56708915700;8558370300;38861027800;7005134081;15127389900;36088544000;35769583500;55883034700;55788882600;6506553245;7004587644;16029719200;","Is the Brewer-Dobson circulation increasing or moving upward?",2016,"10.1002/2015GL067545","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959432209&doi=10.1002%2f2015GL067545&partnerID=40&md5=2783214f75640d18ed94bb67bd25d08d","The meridional circulation of the stratosphere, or Brewer-Dobson circulation (BDC), is projected to accelerate with increasing greenhouse gas (GHG) concentrations. The acceleration is typically quantified by changes in the tropical upward mass flux (Ftrop) across a given pressure surface. Simultaneously, models project a lifting of the entire atmospheric circulation in response to GHGs; notably, the tropopause rises about a kilometer over this century. In this study, it is shown that most of the BDC trend is associated with the rise in the circulation. Using a chemistry-climate model (CCM), Ftrop trends across 100 hPa are contrasted with those across the tropopause: while Ftrop at 100 hPa increases 1-2 %/decade, the mass flux entering the atmosphere above the tropopause actually decreases. Similar results are found for other CCMs, suggesting that changes in the BDC may better be described as an upward shift of the circulation, as opposed to an increase, with implications for the mechanism and stratosphere-troposphere exchange. ©2016. American Geophysical Union. All Rights Reserved."
"9249239700;36150977900;7003278104;57144839900;56130997600;24485218400;36161790500;57044397100;23094149200;6603126554;6505762249;","Considering the radiative effects of snow on tropical Pacific Ocean radiative heating profiles in contemporary GCMs using A-Train observations",2016,"10.1002/2015JD023587","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959419657&doi=10.1002%2f2015JD023587&partnerID=40&md5=24703c4b28ac14c8e819268ce8ef2111","This study characterizes biases in water vapor, dynamics, shortwave (SW) and longwave (LW) radiative properties in contemporary global climate models (GCMs) against observations over tropical Pacific Ocean. The observations are based on Atmospheric Infrared Sounder for water vapor, CloudSat 2B-FLXHR-LIDAR for LW and SW radiative heating profiles, and radiative flux from Clouds and the Earth’s Radiant Energy System products. The model radiative heating profiles are adopted from the coupled and uncoupled National Center for Atmospheric Research (NCAR) Community Earth System Model version 1 (CESM1) and joint Year of Tropical Convection (YOTC)/Madden Julian Oscillation (MJO) Task Force-Global Energy and Water Cycle Experiment Atmospheric System Studies (GASS) Multi-Model Physical Processes Experiment (YOTC-GASS). The results from the model evaluation for YOTC-GASS and NCAR CESM1 demonstrate a number of systematic radiative biases. These biases include excessive outgoing LW radiation and excessive SW surface radiative fluxes, in conjunction with a radiatively unstable atmosphere with excessive LW cooling in the upper troposphere over convectively active areas, such as the Intertropical Convergence Zone/South Pacific Convergence Zone (ITCZ/SPCZ) and warm pool. Using sensitivity experiments with the NCAR-uncoupled/NCAR-coupled CESM1, we infer that these biases partly result from the interactions between falling snow and radiation that are missing in most contemporary GCMs (e.g., YOTC-GASS, Coupled Model Intercomparison Project 3 (CMIP)3, and Atmospheric Model Intercomparison Project 5 (AMIP5)/CMIP5). A number of biases in the YOTC-GASS model simulations are consistent with model biases in CMIP3, AMIP5/CMIP5, and NCAR-uncoupled/NCAR-coupled model simulation without snow-radiation interactions. These include excessive upper level convection and low level downward motion with outflow from ITCZ/SPCZ. This generates weaker low-level trade winds and excessive precipitation in the Central Pacific Trade wind regions. The excessive LW radiative cooling in NCAR-coupled/NCAR-uncoupled GCM simulations is reduced by 10-20% with snow-radiative effects considered. © 2016. American Geophysical Union. All Rights Reserved."
"36836680100;7401471372;56191397900;55243717000;","Impact of model resolution on the simulation of diurnal variations of precipitation over East Asia",2016,"10.1002/2015JD023948","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959441160&doi=10.1002%2f2015JD023948&partnerID=40&md5=acf982afbb1ad6f2fe8400b156c17a2e","The impact of model resolution on the simulation of diurnal variations of precipitation over East Asia during the summer monsoon period of 2006 is investigated by conducting a suite of ensemble simulations of three different cumulus parameterization schemes (CPS), which are Kain-Fritsch, Kain-Fritsch with a modified trigger function, and Simplified Arakawa-Schubert, and the convection-permitting (CP) setting with the Weather Research and Forecasting model. The horizontal resolutions of 50 km, 27 km, and 9 km are applied for each different representation of convection process. Model simulations as a whole are able to mimic the diurnal and semidiurnal cycles with 24 h and 12 h peaks in the morning and the afternoon. However, the simulated afternoon peaks over land are earlier in the CPS runs, while delayed in the CP runs, compared to those observed. The increase of resolution improves the phase and amplitude of diurnal variations in the CP runs due to the explicit representation of the realistic cloud system. In addition, the contribution of nonconvective precipitation from the microphysical process significantly improves the phase of diurnal variations in the CPS runs, especially the afternoon peak over land. The KFtr scheme outperforms other schemes in reproducing the diurnal variations due to the relatively dominant role of nonconvective precipitation. Phase does not change with increasing resolution in the diurnal variations of convective precipitation. Only the modification of the convection scheme, such as the alternative trigger function in the KFtr scheme distinguished from the KF scheme, can make fundamental changes in phase of diurnal variation. © 2016. American Geophysical Union. All Rights Reserved."
"57188731710;8856938500;36449157300;35273004500;7404250633;56487354500;41961546800;7003796684;","An assessment of the Polar Weather Research and Forecasting (WRF) model representation of near-surface meteorological variables over West Antarctica",2016,"10.1002/2015JD024037","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975698113&doi=10.1002%2f2015JD024037&partnerID=40&md5=e7543fea66f15b9df7751222dc09ce8b","Despite the recent significant climatic changes observed over West Antarctica, which include large warming in central West Antarctica and accelerated ice loss, adequate validation of regional simulations of meteorological variables are rare for this region. To address this gap, results from a recent version of the Polar Weather Research and Forecasting model (Polar WRF) covering West Antarctica at a high horizontal resolution of 5 km were validated against near-surface meteorological observations. The model employed physics options that included the Mellor-Yamada-Nakanishi-Niino boundary layer scheme, the WRF Single Moment 5-Class cloud microphysics scheme, the new version of the rapid radiative transfer model for both shortwave and longwave radiation, and the Noah land surface model. Our evaluation finds this model to be a useful tool for realistically capturing the near-surface meteorological conditions. It showed high skill in simulating surface pressure (correlation ≥0.97), good skill for wind speed with better correlation at inland sites (0.7-0.8) compared to coastal sites (0.3-0.6), generally good representation of strong wind events, and good skill for temperature in winter (correlation ≥0.8). The main shortcomings of this configuration of Polar WRF are an occasional failure to properly represent transient cyclones and their influence on coastal winds, an amplified diurnal temperature cycle in summer, and a general tendency to underestimate the wind speed at inland sites in summer. Additional sensitivity studies were performed to quantify the impact of the choice of boundary layer scheme and surface boundary conditions. It is shown that the model is most sensitive to the choice of boundary layer scheme, with the representation of the temperature diurnal cycle in summer significantly improved by selecting the Mellor-Yamada-Janjic boundary layer scheme. By contrast, the model results showed little sensitivity to whether the horizontal resolution was 5 or 15 km. © 2016. American Geophysical Union. All Rights Reserved."
"49662076300;","Black carbon simulations using a size- and mixing-state-resolved three-dimensional model: 2. aging timescale and its impact over East Asia",2016,"10.1002/2015JD023999","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959422732&doi=10.1002%2f2015JD023999&partnerID=40&md5=d28652158f8cfd6fac8bd92df9f92897","This study evaluates the aging timescale and the cloud condensation nuclei (CCN) activity of black carbon (BC) over East Asia and its outflow region using a size- and mixing-state-resolved three-dimensional model, the Weather Research and Forecasting model with chemistry (WRF-chem) with the Aerosol Two-dimensional bin module for foRmation and Aging Simulation (ATRAS) and the Model for Simulating Aerosol Interactions and Chemistry (MOSAIC). The WRF-chem/ATRAS-MOSAIC model explicitly calculates BC aging (condensation and coagulation) and removal processes, with 12 size and 10 BC mixing state bins (128 bins in total). The model reveals large spatial and temporal variability of the BC aging timescale and the CCN activity of BC-containing particles over East Asia (spring 2009) with their strong size and supersaturation dependence. The BC aging timescale differs from 0.19 to 3.1 days (period and domain average at an altitude of 1 km), depending on the choice of size (mass or number) and supersaturation (1.0% or 0.1%). As a result, almost 100% of BC-containing particles are CCN-active at a supersaturation of 1.0%, whereas 20-50% of BC-containing particles are CCN-inactive at a supersaturation of 0.1%, with a strong size dependence. These results show the importance of resolving BC aging processes and their dependence on size and supersaturation in models for more accurate simulations of BC concentrations and their distribution and lifetime. A sensitivity simulation without resolving BC mixing state shows the underestimation of total BC mass concentrations by 5-10% and the BC mass concentrations in the CCN-inactive particles (at a supersaturation of 0.1%) by 40-60% over the outflow region (at 150°E), compared with the simulation resolving BC mixing state. Because BC aging speed is very slow at 150°E and eastward, the change in BC mass and its CCN activity by resolving BC mixing state will continue over long distances and may have a large impact on BC transport from East Asia to remote regions such as North America and the Arctic. © 2015. American Geophysical Union. All Rights Reserved."
"49861577800;57208121852;7405666962;35810775100;10139397300;22978151200;17345303300;7102517130;14059827200;7003666669;56250250300;12139043600;6506718302;55717074000;9275665400;55885662200;8942524900;6603613067;57205638870;12139310900;11940188700;7202079615;6507308842;56384704800;","What controls the vertical distribution of aerosol? Relationships between process sensitivity in HadGEM3-UKCA and inter-model variation from AeroCom Phase II",2016,"10.5194/acp-16-2221-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959421220&doi=10.5194%2facp-16-2221-2016&partnerID=40&md5=c8ba7528caaf28859a04b6fa0c90705e","The vertical profile of aerosol is important for its radiative effects, but weakly constrained by observations on the global scale, and highly variable among different models. To investigate the controlling factors in one particular model, we investigate the effects of individual processes in HadGEM3-UKCA and compare the resulting diversity of aerosol vertical profiles with the inter-model diversity from the AeroCom Phase II control experiment. In this way we show that (in this model at least) the vertical profile is controlled by a relatively small number of processes, although these vary among aerosol components and particle sizes. We also show that sufficiently coarse variations in these processes can produce a similar diversity to that among different models in terms of the global-mean profile and, to a lesser extent, the zonal-mean vertical position. However, there are features of certain models' profiles that cannot be reproduced, suggesting the influence of further structural differences between models. In HadGEM3-UKCA, convective transport is found to be very important in controlling the vertical profile of all aerosol components by mass. In-cloud scavenging is very important for all except mineral dust. Growth by condensation is important for sulfate and carbonaceous aerosol (along with aqueous oxidation for the former and ageing by soluble material for the latter). The vertical extent of biomass-burning emissions into the free troposphere is also important for the profile of carbonaceous aerosol. Boundary-layer mixing plays a dominant role for sea salt and mineral dust, which are emitted only from the surface. Dry deposition and below-cloud scavenging are important for the profile of mineral dust only. In this model, the microphysical processes of nucleation, condensation and coagulation dominate the vertical profile of the smallest particles by number (e.g. total CN > 3 nm), while the profiles of larger particles (e.g. CN > 100 nm) are controlled by the same processes as the component mass profiles, plus the size distribution of primary emissions. We also show that the processes that affect the AOD-normalised radiative forcing in the model are predominantly those that affect the vertical mass distribution, in particular convective transport, in-cloud scavenging, aqueous oxidation, ageing and the vertical extent of biomass-burning emissions. © Author(s) 2016."
"24344988500;","Properties of young contrails - A parametrisation based on large-eddy simulations",2016,"10.5194/acp-16-2059-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959327489&doi=10.5194%2facp-16-2059-2016&partnerID=40&md5=9e534bbd65f87776306fb3e61b8afaab","Contrail-cirrus is probably the largest climate forcing from aviation. The evolution of contrail-cirrus and its radiative impact depends not only on a multitude of atmospheric parameters, but also on the geometric and microphysical properties of the young contrails evolving into contrail-cirrus. The early evolution of contrails (t < 5 min) is dominated by an interplay of ice microphysics and wake vortex dynamics. Young contrails may undergo a fast vertical expansion due to a descent of the wake vortices and may lose a substantial fraction of their ice crystals due to adiabatic heating. The geometric depth H and total ice crystal number N of young contrails are highly variable and depend on many environmental and aircraft parameters. Both properties, H and N, affect the later properties of the evolving contrail-cirrus, as they control the extent of shear-induced spreading and sedimentation losses. In this study, we provide parametrisations of H and N after 5 min taking into account the effects of temperature, relative humidity, thermal stratification and aircraft type (mass, wing span, fuel burn). The parametrisations rely on a large data set of recent large-eddy simulations of young contrails. They are suited to be incorporated in larger-scale models in order to refine the present-day contrail initialisations by considering the processes that strongly affect the contrail evolution during the vortex phase. © 2016 Author(s)."
"57207261095;36676453300;20735974900;16833315000;6603212184;6602443410;6701853225;57206535282;23967608200;17433787100;26643041500;35461255500;7006593624;6602354484;","A chamber study of the influence of boreal BVOC emissions and sulfuric acid on nanoparticle formation rates at ambient concentrations",2016,"10.5194/acp-16-1955-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975784768&doi=10.5194%2facp-16-1955-2016&partnerID=40&md5=48f15cd9e3adf94bf5d91a53d0456b66","Aerosol formation from biogenic and anthropogenic precursor trace gases in continental background areas affects climate via altering the amount of available cloud condensation nuclei. Significant uncertainty still exists regarding the agents controlling the formation of aerosol nanoparticles. We have performed experiments in the Jülich plant-atmosphere simulation chamber with instrumentation for the detection of sulfuric acid and nanoparticles, and present the first simultaneous chamber observations of nanoparticles, sulfuric acid, and realistic levels and mixtures of biogenic volatile compounds (BVOCs). We present direct laboratory observations of nanoparticle formation from sulfuric acid and realistic BVOC precursor vapour mixtures performed at atmospherically relevant concentration levels. We directly measured particle formation rates separately from particle growth rates. From this, we established that in our experiments, the formation rate was proportional to the product of sulfuric acid and biogenic VOC emission strength. The formation rates were consistent with a mechanism in which nucleating BVOC oxidation products are rapidly formed and activate with sulfuric acid. The growth rate of nanoparticles immediately after birth was best correlated with estimated products resulting from BVOC ozonolysis. © Author(s) 2016. CC Attribution 3.0 License."
"35513762000;36770724700;7103323331;6701692024;7007068504;6603667298;57189891880;","Atmospheric circulation patterns, cloud-to-ground lightning, and locally intense convective rainfall associated with debris flow initiation in the Dolomite Alps of northeastern Italy",2016,"10.5194/nhess-16-509-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975678617&doi=10.5194%2fnhess-16-509-2016&partnerID=40&md5=c55fa35bccf5563d3d290ec0238610ec","The Dolomite Alps of northeastern Italy experience debris flows with great frequency during the summer months. An ample supply of unconsolidated material on steep slopes and a summer season climate regime characterized by recurrent thunderstorms combine to produce an abundance of these destructive hydro-geologic events. In the past, debris flow events have been studied primarily in the context of their geologic and geomorphic characteristics. The atmospheric contribution to these mass-wasting events has been limited to recording rainfall and developing intensity thresholds for debris mobilization. This study aims to expand the examination of atmospheric processes that preceded both locally intense convective rainfall (LICR) and debris flows in the Dolomite region. 500hPa pressure level plots of geopotential heights were constructed for a period of 3 days prior to debris flow events to gain insight into the synoptic-scale processes which provide an environment conducive to LICR in the Dolomites. Cloud-to-ground (CG) lightning flash data recorded at the meso-scale were incorporated to assess the convective environment proximal to debris flow source regions. Twelve events were analyzed and from this analysis three common synoptic-scale circulation patterns were identified. Evaluation of CG flashes at smaller spatial and temporal scales illustrated that convective processes vary in their production of CF flashes (total number) and the spatial distribution of flashes can also be quite different between events over longer periods. During the 60min interval immediately preceding debris flow a majority of cases exhibited spatial and temporal colocation of LICR and CG flashes. Also a number of CG flash parameters were found to be significantly correlated to rainfall intensity prior to debris flow initiation."
"56149492300;56942554300;56003666300;55462884000;56612517400;36538539800;","Decadal evaluation of regional climate, air quality, and their interactions over the continental US and their interactions using WRF/Chem version 3.6.1",2016,"10.5194/gmd-9-671-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959088700&doi=10.5194%2fgmd-9-671-2016&partnerID=40&md5=a89632cada4d16fda50fccdd0b004d62","The Weather Research and Forecasting model with Chemistry (WRF/Chem) v3.6.1 with the Carbon Bond 2005 (CB05) gas-phase mechanism is evaluated for its first decadal application during 2001-2010 using the Representative Concentration Pathway 8.5 (RCP 8.5) emissions to assess its capability and appropriateness for long-term climatological simulations. The initial and boundary conditions are downscaled from the modified Community Earth System Model/Community Atmosphere Model (CESM/CAM5) v1.2.2. The meteorological initial and boundary conditions are bias-corrected using the National Center for Environmental Protection's Final (FNL) Operational Global Analysis data. Climatological evaluations are carried out for meteorological, chemical, and aerosol-cloud-radiation variables against data from surface networks and satellite retrievals. The model performs very well for the 2 m temperature (T2) for the 10-year period, with only a small cold bias of - '0.3 °C. Biases in other meteorological variables including relative humidity at 2 m, wind speed at 10 m, and precipitation tend to be site-and season-specific; however, with the exception of T2, consistent annual biases exist for most of the years from 2001 to 2010. Ozone mixing ratios are slightly overpredicted at both urban and rural locations with a normalized mean bias (NMB) of 9.7 % but underpredicted at rural locations with an NMB of-8.8 %. PM2.5 concentrations are moderately overpredicted with an NMB of 23.3 % at rural sites but slightly underpredicted with an NMB of-10.8 % at urban/suburban sites. In general, the model performs relatively well for chemical and meteorological variables, and not as well for aerosol-cloud-radiation variables. Cloud-aerosol variables including aerosol optical depth, cloud water path, cloud optical thickness, and cloud droplet number concentration are generally underpredicted on average across the continental US. Overpredictions of several cloud variables over the eastern US result in underpredictions of radiation variables (such as net shortwave radiation-GSW-with a mean bias-MB-of-5.7 W m-2) and overpredictions of shortwave and longwave cloud forcing (MBs of-7 to 8 W m-2), which are important climate variables. While the current performance is deemed to be acceptable, improvements to the bias-correction method for CESM downscaling and the model parameterizations of cloud dynamics and thermodynamics, as well as aerosol-cloud interactions, can potentially improve model performance for long-term climate simulations. © 2016 Author(s)."
"24081888700;6603081424;26645289600;57203386948;7401776640;7102517130;57208765879;7401793588;","Positive low cloud and dust feedbacks amplify tropical North Atlantic Multidecadal Oscillation",2016,"10.1002/2016GL067679","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959387760&doi=10.1002%2f2016GL067679&partnerID=40&md5=f48ac0d7378d525442313ff11a864124","The Atlantic Multidecadal Oscillation (AMO) is characterized by a horseshoe pattern of sea surface temperature (SST) anomalies and has a wide range of climatic impacts. While the tropical arm of AMO is responsible for many of these impacts, it is either too weak or completely absent in many climate model simulations. Here we show, using both observational and model evidence, that the radiative effect of positive low cloud and dust feedbacks is strong enough to generate the tropical arm of AMO, with the low cloud feedback more dominant. The feedbacks can be understood in a consistent dynamical framework: weakened tropical trade wind speed in response to a warm middle latitude SST anomaly reduces dust loading and low cloud fraction over the tropical Atlantic, which warms the tropical North Atlantic SST. Together they contribute to the appearance of the tropical arm of AMO. Most current climate models miss both the critical wind speed response and two positive feedbacks though realistic simulations of them may be essential for many climatic studies related to the AMO. © 2016. The Authors."
"54897465300;56457851700;7202145115;","Observational evidence for a negative shortwave cloud feedback in middle to high latitudes",2016,"10.1002/2015GL067499","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976240378&doi=10.1002%2f2015GL067499&partnerID=40&md5=798d9ad3419d66db4674a0fbe9ad9399","Exploiting the observed robust relationships between temperature and optical depth in extratropical clouds, we calculate the shortwave cloud feedback from historical data, by regressing observed and modeled cloud property histograms onto local temperature in middle to high southern latitudes. In this region, all CMIP5 models and observational data sets predict a negative cloud feedback, mainly driven by optical thickening. Between 45° and 60°S, the mean observed shortwave feedback (-0.91 ± 0.82 W m-2 K-1, relative to local rather than global mean warming) is very close to the multimodel mean feedback in RCP8.5 (-0.98 W m-2 K-1), despite differences in the meridional structure. In models, historical temperature-cloud property relationships reliably predict the forced RCP8.5 response. Because simple theory predicts this optical thickening with warming, and cloud amount changes are relatively small, we conclude that the shortwave cloud feedback is very likely negative in the real world at middle to high latitudes. © 2016. American Geophysical Union. All Rights Reserved."
"57133112900;6701580874;6603568514;57206174471;7005265210;","The northward March of summer low cloudiness along the California coast",2016,"10.1002/2015GL067081","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84976248265&doi=10.1002%2f2015GL067081&partnerID=40&md5=72f4f7193b3bd654c2d45516a642770e","A new satellite-derived low cloud retrieval reveals rich spatial texture and coherent space-time propagation in summertime California coastal low cloudiness (CLC). Throughout the region, CLC is greatest during May-September but has considerable monthly variability within this summer season. On average, June is cloudiest along the coast of southern California and northern Baja, Mexico, while July is cloudiest along northern California's coast. Over the course of the summer, the core of peak CLC migrates northward along coastal California, reaching its northernmost extent in late July/early August, then recedes while weakening. The timing and movement of the CLC climatological structure is related to the summer evolution of lower tropospheric stability and both its component parts, sea surface temperature and potential temperature at 700 hPa. The roughly coincident seasonal timing of peak CLC with peak summertime temperatures translates into the strongest heat-modulating capacity of CLC along California's north coast. © 2016. American Geophysical Union. All Rights Reserved."
"55682851300;6505932008;","Cold pool dissipation",2016,"10.1002/2015JD023813","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975709489&doi=10.1002%2f2015JD023813&partnerID=40&md5=0916562559835fb4ae2fd5cdd340432f","The mechanisms by which sensible heat fluxes (SHFs) alter cold pool characteristics and dissipation rates are investigated in this study using idealized two-dimensional numerical simulations and an environment representative of daytime, dry, continental conditions. Simulations are performed with no SHFs, SHFs calculated using a bulk formula, and constant SHFs for model resolutions with horizontal (vertical) grid spacings ranging from 50 m (25 m) to 400 m (200 m). In the highest resolution simulations, turbulent entrainment of environmental air into the cold pool is an important mechanism for dissipation in the absence of SHFs. Including SHFs enhances cold pool dissipation rates, but the processes responsible for the enhanced dissipation differ depending on the SHF formulation. The bulk SHFs increase the near-surface cold pool temperatures, but their effects on the overall cold pool characteristics are small, while the constant SHFs influence the near-surface environmental stability and the turbulent entrainment rates into the cold pool. The changes to the entrainment rates are found to be the most significant of the SHF effects on cold pool dissipation. SHFs may also influence the timing of cold pool-induced convective initiation by altering the environmental stability and the cold pool intensity. As the model resolution is coarsened, cold pool dissipation is found to be less sensitive to SHFs. Furthermore, the coarser resolution simulations not only poorly but sometimes wrongly represent the SHF impacts on the cold pools. Recommendations are made regarding simulating the interaction of cold pools with convection and the land surface in cloud-resolving models. © 2016. American Geophysical Union. All Rights Reserved."
"56066042400;7003571545;13907769500;","Isotopic modeling of the sub-cloud evaporation effect in precipitation",2016,"10.1016/j.scitotenv.2015.11.072","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84953410925&doi=10.1016%2fj.scitotenv.2015.11.072&partnerID=40&md5=1d8b97b888bcd916f4c3231a9bf803eb","In dry and warm environments sub-cloud evaporation influences the falling raindrops modifying their final stable isotopic content. During their descent from the cloud base towards the ground surface, through the unsaturated atmosphere, hydrometeors are subjected to evaporation whereas the kinetic fractionation results to less depleted or enriched isotopic signatures compared to the initial isotopic composition of the raindrops at cloud base. Nowadays the development of Generalized Climate Models (GCMs) that include isotopic content calculation modules are of great interest for the isotopic tracing of the global hydrological cycle. Therefore the accurate description of the underlying processes affecting stable isotopic content can improve the performance of iso-GCMs. The aim of this study is to model the sub-cloud evaporation effect using a) mixing and b) numerical isotope evaporation models. The isotope-mixing evaporation model simulates the isotopic enrichment (difference between the ground and the cloud base isotopic composition of raindrops) in terms of raindrop size, ambient temperature and relative humidity (RH) at ground level. The isotopic enrichment (δδ) varies linearly with the evaporated raindrops mass fraction of the raindrop resulting to higher values at drier atmospheres and for smaller raindrops. The relationship between δδ and RH is described by a 'heat capacity' model providing high correlation coefficients for both isotopes (R2&gt;80%) indicating that RH is an ideal indicator of the sub-cloud evaporation effect. Vertical distribution of stable isotopes in falling raindrops is also investigated using a numerical isotope-evaporation model. Temperature and humidity dependence of the vertical isotopic variation is clearly described by the numerical isotopic model showing an increase in the isotopic values with increasing temperature and decreasing RH. At an almost saturated atmosphere (RH=95%) sub-cloud evaporation is negligible and the isotopic composition hardly changes even at high temperatures while at drier and warm conditions the enrichment of 18O reaches up to 20‰, depending on the raindrop size and the initial meteorological conditions. © 2015 Elsevier B.V."
"56502475700;8686475900;36182467000;7402833686;","Plant water-stress parameterization determines the strength of land-atmosphere coupling",2016,"10.1016/j.agrformet.2015.11.006","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949035155&doi=10.1016%2fj.agrformet.2015.11.006&partnerID=40&md5=e57a9178c3382595d34d4ea2a8404e76","Land-surface models used in studies of the atmosphere and vegetation during droughts usually include an underlying parameterization that describes the response of plants to water stress. Here, we show that different formulations of this parameterization can lead to significant differences in the coupling strength (i.e. the magnitude of the carbon and water exchange) between the land surface and the atmospheric boundary layer (ABL). We use a numerical model that couples the daytime surface fluxes typical for low vegetation to the dynamics of a convective ABL, to systematically investigate a range of plant water-stress responses. We find that under dry soil conditions, changing from a sensitive to an insensitive vegetation response to water stress has the same impact on the land-atmosphere (L-A) coupling as a strong increase in soil moisture content. The insensitive vegetation allows stomata to remain open for transpiration (+150Wm-2 compared to the sensitive one), which cools the atmosphere (-3.5K) and limits the ABL growth (-500m). During the progressive development of a dry spell, the insensitive response will first dampen atmospheric heating because the vegetation continues to transpire a maximum of 4.6mmday-1 while soil moisture is available. In contrast, the more sensitive vegetation response reduces its transpiration by more than 1mmday-1 to prevent soil moisture depletion. But when soil moisture comes close to wilting point, the insensitive vegetation will suddenly close its stomata causing a switch to a L-A coupling regime dominated by sensible heat exchange. We find that in both cases, progressive soil moisture depletion contributes to further atmospheric warming up to 6K, reduced photosynthesis up to 89%, and CO2 enrichment up to 30ppm, but the full impact is strongly delayed for the insensitive vegetation. Then, when we analyze the impact of a deviation of the modeled large-scale boundary conditions (e.g. subsidence, cloud cover, free-troposphere lapse rates, etc.) from their true state during a drought, we find that the two coupled systems (with a sensitive or insensitive vegetation) respond much differently to the generated atmospheric warming, this due to the difference in the basic surface coupling regime (coupled vs. uncoupled). This is of importance for the simulation of heat waves and meteorological droughts, as well as carbon-climate projections, as we show the predictive skill of coupled models is tied to the underlying vegetation response to water stress. © 2015 Elsevier B.V.."
"56479783600;7102294773;7601490850;28568055900;55322254600;15047161300;57218416169;35265615300;","Modeling study of the 2010 regional haze event in the North China Plain",2016,"10.5194/acp-16-1673-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958261007&doi=10.5194%2facp-16-1673-2016&partnerID=40&md5=b274d58b0e8cdcf1142e7868871c6de3","The online coupled Weather Research and Forecasting-Chemistry (WRF-Chem) model was applied to simulate a haze event that happened in January 2010 in the North China Plain (NCP), and was validated against various types of measurements. The evaluations indicate that WRFChem provides reliable simulations for the 2010 haze event in the NCP. This haze event was mainly caused by high emissions of air pollutants in the NCP and stable weather conditions in winter. Secondary inorganic aerosols also played an important role and cloud chemistry had important contributions. Air pollutants outside Beijing contributed about 64.5% to the PM2.5 levels in Beijing during this haze event, and most of them are from south Hebei, Tianjin city, Shandong and Henan provinces. In addition, aerosol feedback has important impacts on surface temperature, relative humidity (RH) and wind speeds, and these meteorological variables affect aerosol distribution and formation in turn. In Shijiazhuang, Planetary Boundary Layer (PBL) decreased about 278.2m and PM2.5 increased more than 20 μgm-3 due to aerosol feedback. It was also shown that black carbon (BC) absorption has significant impacts on meteorology and air quality changes, indicating more attention should be paid to BC from both air pollution control and climate change perspectives. © 2016 Author(s)."
"55823600500;7003782348;","Cloud effects on surface energy and mass balance in the ablation area of Brewster Glacier, New Zealand",2016,"10.5194/tc-10-313-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958961751&doi=10.5194%2ftc-10-313-2016&partnerID=40&md5=148981a6d8ab2ee897531a1276d1bab4","The effect of clouds on glacier surface energy balance (SEB) has received increased attention in the last decade, but how clouds interact with other meteorological forcing to influence surface mass balance (SMB) is not as well understood. This paper resolves the SEB and SMB at a site in the ablation zone of Brewster Glacier over a 22-month period, using high-quality radiation data to carefully evaluate SEB terms and define clear-sky and overcast conditions. A fundamental change in glacier SEB in cloudy conditions was driven by increased effective sky emissivity and surface vapour pressure, rather than a minimal change in air temperature and wind speed. During overcast conditions, positive net long-wave radiation and latent heat fluxes allowed melt to be maintained through a much greater length of time compared to clear-sky conditions, and led to similar melt in each sky condition. The sensitivity of SMB to changes in air temperature was greatly enhanced in overcast compared to clear-sky conditions due to more frequent melt and changes in precipitation phase that created a strong albedo feedback. During the spring and autumn seasons, the sensitivity during overcast conditions was strongest. To capture these processes, future attempts to explore glacier-climate interactions should aim to resolve the effects of atmospheric moisture (vapour, cloud, and precipitation) on melt as well as accumulation, through enhanced statistical or physically based methods. © Author(s) 2016."
"55207713000;7004299063;55893823700;26533129200;","Stratospheric sulfate geoengineering could enhance the terrestrial photosynthesis rate",2016,"10.5194/acp-16-1479-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958212542&doi=10.5194%2facp-16-1479-2016&partnerID=40&md5=31abdda71ca64907f949a2aa2f2eb441","Stratospheric sulfate geoengineering could impact the terrestrial carbon cycle by enhancing the carbon sink. With an 8 Tg yr-1 injection of SO2 to produce a stratospheric aerosol cloud to balance anthropogenic radiative forcing from the Representative Concentration Pathway 6.0 (RCP6.0) scenario, we conducted climate model simulations with the Community Earth System Model . the Community Atmospheric Model 4 fully coupled to tropospheric and stratospheric chemistry (CAM4.chem). During the geoengineering period, as compared to RCP6.0, landaveraged downward visible (300.700 nm) diffuse radiation increased 3.2Wm-2 (11 %). The enhanced diffuse radiation combined with the cooling increased plant photosynthesis by 0.07±0.02 μ molCm-2 s-1, which could contribute to an additional 3.8±1.1 GtC yr-1 global gross primary productivity without explicit nutrient limitation. This increase could potentially increase the land carbon sink. Suppressed plant and soil respiration due to the cooling would reduce natural land carbon emission and therefore further enhance the terrestrial carbon sink during the geoengineering period. This potentially beneficial impact of stratospheric sulfate geoengineering would need to be balanced by a large number of potential risks in any future decisions about the implementation of geoengineering. © 2015 The Author(s)."
"56033201200;6701905330;8109118600;7005753600;6701802669;55636317253;","Observations of surface momentum exchange over the marginal ice zone and recommendations for its parametrisation",2016,"10.5194/acp-16-1545-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958206580&doi=10.5194%2facp-16-1545-2016&partnerID=40&md5=28fc39ee1cf7f67a8d22a482bc07f3d6","Comprehensive aircraft observations are used to characterise surface roughness over the Arctic marginal ice zone (MIZ) and consequently make recommendations for the parametrisation of surface momentum exchange in the MIZ. These observations were gathered in the Barents Sea and Fram Strait from two aircraft as part of the Aerosol-Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) project. They represent a doubling of the total number of such aircraft observations currently available over the Arctic MIZ. The eddy covariance method is used to derive estimates of the 10m neutral drag coefficient (CDN10) from turbulent wind velocity measurements, and a novel method using albedo and surface temperature is employed to derive ice fraction. Peak surface roughness is found at ice fractions in the range 0.6 to 0.8 (with a mean interquartile range in CDN10 of 1.25 to 2.85 × 10-3). CDN10 as a function of ice fraction is found to be well approximated by the negatively skewed distribution provided by a leading parametrisation scheme (Lüpkes et al., 2012) tailored for sea-ice drag over the MIZ in which the two constituent components of drag-skin and form drag-are separately quantified. Current parametrisation schemes used in the weather and climate models are compared with our results and the majority are found to be physically unjustified and unrepresentative. The Lüpkes et al. (2012) scheme is recommended in a computationally simple form, with adjusted parameter settings. A good agreement holds for subsets of the data from different locations, despite differences in sea-ice conditions. Ice conditions in the Barents Sea, characterised by small, unconsolidated ice floes, are found to be associated with higher CDN10 values-especially at the higher ice fractions-than those of Fram Strait, where typically larger, smoother floes are observed. Consequently, the important influence of sea-ice morphology and floe size on surface roughness is recognised, and improvement in the representation of this in parametrisation schemes is suggested for future study. © 2016 Author(s)."
"55717074000;15755995900;55688930000;55893823700;55544607500;7006270084;7003666669;7006705919;","Description and evaluation of a new four-mode version of the Modal Aerosol Module (MAM4) within version 5.3 of the Community Atmosphere Model",2016,"10.5194/gmd-9-505-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957971008&doi=10.5194%2fgmd-9-505-2016&partnerID=40&md5=f0290267bc923720ce2a95d8d13e09a6","Atmospheric carbonaceous aerosols play an important role in the climate system by influencing the Earth's radiation budgets and modifying the cloud properties. Despite the importance, their representations in large-scale atmospheric models are still crude, which can influence model simulated burden, lifetime, physical, chemical and optical properties, and the climate forcing of carbonaceous aerosols. In this study, we improve the current three-mode version of the Modal Aerosol Module (MAM3) in the Community Atmosphere Model version 5 (CAM5) by introducing an additional primary carbon mode to explicitly account for the microphysical ageing of primary carbonaceous aerosols in the atmosphere. Compared to MAM3, the four-mode version of MAM (MAM4) significantly increases the column burdens of primary particulate organic matter (POM) and black carbon (BC) by up to 40% in many remote regions, where in-cloud scavenging plays an important role in determining the aerosol concentrations. Differences in the column burdens for other types of aerosol (e.g., sulfate, secondary organic aerosols, mineral dust, sea salt) are less than 1%. Evaluating the MAM4 simulation against in situ surface and aircraft observations, we find that MAM4 significantly improves the simulation of seasonal variation of near-surface BC concentrations in the polar regions, by increasing the BC concentrations in all seasons and particularly in cold seasons. However, it exacerbates the overestimation of modeled BC concentrations in the upper troposphere in the Pacific regions. The comparisons suggest that, to address the remaining model POM and BC biases, future improvements are required related to (1) in-cloud scavenging and vertical transport in convective clouds and (2) emissions of anthropogenic and biomass burning aerosols. © Author(s) 2016."
"6602935023;22946301100;57192916482;35794560500;8544882500;16315817300;23012388900;23567914700;57217323583;26430632200;24341507700;55984584000;56275096000;7801500046;57220005954;7801446979;36959386700;57113384600;23397135300;57217907313;9844993400;6603126733;7401837283;7402129369;6507863211;6603023560;54420877100;35265291900;55567619900;9233141200;25637638400;8667844900;7003861526;6602579458;6701498473;8667845600;6602903407;8132538500;6603203838;7005829052;23020325200;35424750900;","Overview of the O3M SAF GOME-2 operational atmospheric composition and UV radiation data products and data availability",2016,"10.5194/amt-9-383-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957951157&doi=10.5194%2famt-9-383-2016&partnerID=40&md5=31fb54d652a42e3c30747ded4e560c6c","The three Global Ozone Monitoring Experiment-2 instruments will provide unique and long data sets for atmospheric research and applications. The complete time period will be 2007-2022, including the period of ozone depletion as well as the beginning of ozone layer recovery. Besides ozone chemistry, the GOME-2 (Global Ozone Monitoring Experiment-2) products are important e.g. for air quality studies, climate modelling, policy monitoring and hazard warnings. The heritage for GOME-2 is in the ERS/GOME and Envisat/SCIAMACHY instruments. The current Level 2 (L2) data cover a wide range of products such as ozone and minor trace gas columns (NO2, BrO, HCHO, H2O, SO2), vertical ozone profiles in high and low spatial resolution, absorbing aerosol indices, surface Lambertian-equivalent reflectivity database, clear-sky and cloud-corrected UV indices and surface UV fields with different weightings and photolysis rates. The Satellite Application Facility on Ozone and Atmospheric Chemistry Monitoring (O3M SAF) processes and disseminates data 24/7. Data quality is guaranteed by the detailed review processes for the algorithms, validation of the products as well as by a continuous quality monitoring of the products and processing. This paper provides an overview of the O3M SAF project background, current status and future plans for the utilisation of the GOME-2 data. An important focus is the provision of summaries of the GOME-2 products including product principles and validation examples together with sample images. Furthermore, this paper collects references to the detailed product algorithm and validation papers. © Author(s) 2016."
"24480463300;57093496500;8568391400;55682775100;23995325300;36719980500;36623061000;6701461735;6602753217;7003984086;6701764148;57094000100;6701481405;","Aerosol size distribution seasonal characteristics measured in Tiksi, Russian Arctic",2016,"10.5194/acp-16-1271-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956883988&doi=10.5194%2facp-16-1271-2016&partnerID=40&md5=2152da7c37a10e3e43300e3f8a6d616c","Four years of continuous aerosol number size distribution measurements from the Arctic Climate Observatory in Tiksi, Russia, are analyzed. Tiksi is located in a region where in situ information on aerosol particle properties has not been previously available. Particle size distributions were measured with a differential mobility particle sizer (in the diameter range of 7-500 nm) and with an aerodynamic particle sizer (in the diameter range of 0.5-10 mu;m). Source region effects on particle modal features and number, and mass concentrations are presented for different seasons. The monthly median total aerosol number concentration in Tiksi ranges from 184cm-3 in November to 724cm-3 in July, with a local maximum in March of 481cm-3. The total mass concentration has a distinct maximum in February-March of 1.72-2.38 mu;m minus;3 and two minimums in June (0.42 mu;m minus;3) and in September-October (0.36-0.57 mu;m minus;3). These seasonal cycles in number and mass concentrations are related to isolated processes and phenomena such as Arctic haze in early spring, which increases accumulation and coarse-mode numbers, and secondary particle formation in spring and summer, which affects the nucleation and Aitken mode particle concentrations. Secondary particle formation was frequently observed in Tiksi and was shown to be slightly more common in marine, in comparison to continental, air flows. Particle formation rates were the highest in spring, while the particle growth rates peaked in summer. These results suggest two different origins for secondary particles, anthropogenic pollution being the important source in spring and biogenic emissions being significant in summer. The impact of temperature-dependent natural emissions on aerosol and cloud condensation nuclei numbers was significant: the increase in both the particle mass and the CCN (cloud condensation nuclei) number with temperature was found to be higher than in any previous study done over the boreal forest region. In addition to the precursor emissions of biogenic volatile organic compounds, the frequent Siberian forest fires, although far away, are suggested to play a role in Arctic aerosol composition during the warmest months. Five fire events were isolated based on clustering analysis, and the particle mass and cloud condensation nuclei number were shown to be somewhat affected by these events. In addition, during calm and cold months, aerosol concentrations were occasionally increased by local aerosol sources in trapping inversions. These results provide valuable information on interannual cycles and sources of Arctic aerosols. © 2016 Author(s)."
"57191899832;6701638149;16318145300;57191906625;","Identification and climatology of alpine pumping from a regional climate simulation",2016,"10.3389/feart.2016.00005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994609157&doi=10.3389%2ffeart.2016.00005&partnerID=40&md5=96a8579ba1e5174f1cc39b605718ffe6","The thermally driven circulation between the European Alps and the Alpine foreland—named Alpine pumping—occurs regularly under clear and calm weather conditions. While previous studies focused on the impact of Alpine pumping on moist convection and transport of air pollutants, this study was motivated by its ventilation effect for Munich, located about 50 km north of the Alps in undulating and only slightly inclined terrain, where local thermal circulations are weak. Hourly data from a reanalysis driven regional climate simulation with COSMO-CLM model for the period 1989–2008 were analyzed to identify days with Alpine pumping and to determine the mean diurnal characteristics of this regional thermal circulation. Four literature derived combinations of meteorological criteria were tested to identify days favorable for Alpine pumping from COSMO-CLM results. The first criterion selects days with a daily sum of solar radiation ≥20MJ/m2 and has been used in an earlier observational study. On average 60 day/year are fulfilling the criterion in the model simulation, which compares well to the 67 day/year determined from observations. The other three criteria combinations consider a maximum wind velocity at 850 hPa, a maximum daily precipitation sum, and/or a maximummean cloud cover. The mean annual number of selected days is lower for these criteria combinations and ranges between 20 and 52. Diurnal wind reversals occur on 77–81%of the selected days, depending on the criteria combination. The daily solar radiation sum of 20 MJ/m2 is only exceeded during April to September, while days satisfying the criteria combinations without the radiation threshold occur all year round. In agreement with observations, the simulated regional thermally driven wind field extends up to ∼100 km north of the Alps with average near-surface wind speeds of 0.5–1.5 m/s in the Munich area. With increasing distance from the Alps, the diurnal cycle of Alpine pumping is delayed by up to 3h. The simulated mean depth of the daytime inflow layer ranges between 500 and 1500 m, whereas the depth of the nocturnal outflow layer typically reaches up to a few hundred meters. © 2016 Graf, Kossmann, Trusilova and Mühlbacher."
"57197233116;8696069500;7201504886;6602845217;55111818600;56005080300;23082420800;","Amplification of El Nino by cloud longwave coupling to atmospheric circulation",2016,"10.1038/ngeo2630","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957072704&doi=10.1038%2fngeo2630&partnerID=40&md5=9fc008ad5baadce04026f3709aa7078c","The El Nino/Southern Oscillation (ENSO) is the dominant mode of inter-annual variability, with major impacts on social and ecological systems through its influence on extreme weather, droughts and floods. The ability to forecast El Nino, as well as anticipate how it may change with warming, requires an understanding of the underlying physical mechanisms that drive it. Among these, the role of atmospheric processes remains poorly understood. Here we present numerical experiments with an Earth system model, with and without coupling of cloud radiative effects to the circulation, suggesting that clouds enhance ENSO variability by a factor of two or more. Clouds induce heating in the mid and upper troposphere associated with enhanced high-level cloudiness over the El Nino region, and low-level clouds cool the lower troposphere in the surrounding regions. Together, these effects enhance the coupling of the atmospheric circulation to El Nino surface temperature anomalies, and thus strengthen the positive Bjerknes feedback mechanism between west Pacific zonal wind stress and sea surface temperature gradients. Behaviour consistent with the proposed mechanism is robustly represented in other global climate models and in satellite observations. The mechanism suggests that the response of ENSO amplitude to climate change will in part be determined by a balance between increasing cloud longwave feedback and a possible reduction in the area covered by upper-level clouds. © 2016 Macmillan Publishers Limited."
"55834717600;6603792921;35274776300;7006575711;7003855730;","Toward Improved Solar Irradiance Forecasts: a Simulation of Deep Planetary Boundary Layer with Scattered Clouds Using the Weather Research and Forecasting Model",2016,"10.1007/s00024-015-1072-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957954538&doi=10.1007%2fs00024-015-1072-3&partnerID=40&md5=892aef9eb93bac34051a0f51ef14f9f6","Accurate forecasts of solar irradiance are required for electric utilities to economically integrate substantial amounts of solar power into their power generation portfolios. A common failing of numerical weather models is the prediction of scattered clouds at the top of deep PBL which are generally difficult to be resolved due to complicated processes in the planetary boundary layer. We improved turbulence parameterization for better predicting solar irradiance during the scattered clouds’ events using the Weather Research and Forecasting model. Sensitivity tests show that increasing the exchange coefficient leads to enhanced vertical mixing and a deeper mixed layer. At the top of mixed layer, an adiabatically ascending air parcel achieved the water vapor saturation and finally scattered cloud is generated. © 2015, Springer Basel."
"55131452100;6701767636;56968202800;7102731342;23568277500;57215023493;6603019813;7005695804;7004237717;7404021123;24588327400;22996291800;25642292900;","The Biodiversity and Climate Change Virtual Laboratory: Where ecology meets big data",2016,"10.1016/j.envsoft.2015.10.025","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84951566654&doi=10.1016%2fj.envsoft.2015.10.025&partnerID=40&md5=dc75859c28ac10324a63b9d39ba93874","Advances in computing power and infrastructure, increases in the number and size of ecological and environmental datasets, and the number and type of data collection methods, are revolutionizing the field of Ecology. To integrate these advances, virtual laboratories offer a unique tool to facilitate, expedite, and accelerate research into the impacts of climate change on biodiversity. We introduce the uniquely cloud-based Biodiversity and Climate Change Virtual Laboratory (BCCVL), which provides access to numerous species distribution modelling tools; a large and growing collection of biological, climate, and other environmental datasets; and a variety of experiment types to conduct research into the impact of climate change on biodiversity.Users can upload and share datasets, potentially increasing collaboration, cross-fertilisation of ideas, and innovation among the user community. Feedback confirms that the BCCVL's goals of lowering the technical requirements for species distribution modelling, and reducing time spent on such research, are being met. © 2015 The Authors."
"7103033688;7402176334;7202355164;16230925400;","Pattern scaling using ClimGen: monthly-resolution future climate scenarios including changes in the variability of precipitation",2016,"10.1007/s10584-015-1509-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959211137&doi=10.1007%2fs10584-015-1509-9&partnerID=40&md5=bf3a811a27ae0089e075a89ce5bc494b","Development, testing and example applications of the pattern-scaling approach for generating future climate change projections are reported here, with a focus on a particular software application called “ClimGen”. A number of innovations have been implemented, including using exponential and logistic functions of global-mean temperature to represent changes in local precipitation and cloud cover, and interpolation from climate model grids to a finer grid while taking into account land-sea contrasts in the climate change patterns. Of particular significance is a new approach for incorporating changes in the inter-annual variability of monthly precipitation simulated by climate models. This is achieved by diagnosing simulated changes in the shape of the gamma distribution of monthly precipitation totals, applying the pattern-scaling approach to estimate changes in the shape parameter under a future scenario, and then perturbing sequences of observed precipitation anomalies so that their distribution changes according to the projected change in the shape parameter. The approach cannot represent changes to the structure of climate timeseries (e.g. changed autocorrelation or teleconnection patterns) were they to occur, but is shown here to be more successful at representing changes in low precipitation extremes than previous pattern-scaling methods. © 2015, The Author(s)."
"56001325100;56432506300;6603327055;14322050300;","Sensitivity analysis with the regional climate model COSMO-CLM over the CORDEX-MENA domain",2016,"10.1007/s00703-015-0403-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955337252&doi=10.1007%2fs00703-015-0403-3&partnerID=40&md5=182b06f089dbb46f83078161dc7ea05c","The results of a sensitivity work based on ERA-Interim driven COSMO-CLM simulations over the Middle East-North Africa (CORDEX-MENA) domain are presented. All simulations were performed at 0.44° spatial resolution. The purpose of this study was to ascertain model performances with respect to changes in physical and tuning parameters which are mainly related to surface, convection, radiation and cloud parameterizations. Evaluation was performed for the whole CORDEX-MENA region and six sub-regions, comparing a set of 26 COSMO-CLM runs against a combination of available ground observations, satellite products and reanalysis data to assess temperature, precipitation, cloud cover and mean sea level pressure. The model proved to be very sensitive to changes in physical parameters. The optimized configuration allows COSMO-CLM to improve the simulated main climate features of this area. Its main characteristics consist in the new parameterization of albedo, based on Moderate Resolution Imaging Spectroradiometer data, and the new parameterization of aerosol, based on NASA-GISS AOD distributions. When applying this configuration, Mean Absolute Error values for the considered variables are as follows: about 1.2 °C for temperature, about 15 mm/month for precipitation, about 9 % for total cloud cover, and about 0.6 hPa for mean sea level pressure. © 2015, Springer-Verlag Wien."
"7202304406;15050523700;15047538100;","Does the modification in “critical relative humidity” of NCEP CFSv2 dictate Indian mean summer monsoon forecast? Evaluation through thermodynamical and dynamical aspects",2016,"10.1007/s00382-015-2640-z","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957426869&doi=10.1007%2fs00382-015-2640-z&partnerID=40&md5=b4bd816340e70630c59b1417b31a687c","An accurate seasonal prediction of Indian summer monsoon rainfall (ISMR) is intriguing as well as the most challenging job for monsoon meteorologists. As there is a cause and effect relationship between clouds and precipitation, the modulation of cloud formation in a dynamical model affects profoundly on ISMR. It has already been established that the critical relative humidity (CRH) plays a crucial role on the realistic cloud formation in a general circulation model. Hence, it may be hypothesized that the proper choice of CRH can be instrumental in driving the large scale Indian monsoon by modulating the cloud formation in a global climate model. An endeavor has been made for the first time to test the above hypothesis on the NCEP-CFSv2 model in the perspective of seasonal prediction of ISMR by modifying the CRH profile. The model sensitivity experiments have been carried out for two different CRH profiles along with the existing profile during the normal (2003) and deficient (2009) monsoon years. First profile is the constant CRH following the existing one but with increased magnitude and the second one is the variable CRH at different cloud levels based on the observations and MERRA reanalysis. The ensemble mean of model runs for four initial conditions of each year has revealed that the variable CRH profile in CFSv2 represents seasonal ISMR and its variability best among the three CRH experiments linking with the thermodynamical and dynamical parameters like precipitable water, tropospheric temperature and its gradient, cloud structure and radiation, water vapour flux, systematic error energy with its nonlinear error growth and the length of the rainy seasons during the contrasting years. It has also been shown that the improved depiction of seasonal ISMR has been achieved without disturbing much the forecast biases at other global tropical regions. The indigenous part of this paper is that the CRH modification can play a seminal role in modulating the large scale system like Indian monsoon by representing the realistic variability of cloud formation in CFSv2 and that proves the hypothesis. This work creates an avenue for further development of CFSv2 approaching towards an accurate seasonal forecast of ISMR. © 2015, Springer-Verlag Berlin Heidelberg."
"55430046100;57218273453;57139379600;56962915800;","Tracing the source of ENSO simulation differences to the atmospheric component of two CGCMs",2016,"10.1002/asl.637","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956732497&doi=10.1002%2fasl.637&partnerID=40&md5=cf9334b13b27adb4bd3bdc99884408e9","To explore why the Community Earth System Model (CESM) exhibits too strong El Niño-Southern Oscillation (ENSO), its atmospheric component is replaced by another Atmospheric General Circulation Model (AGCM). Differences among the two simulations and another 'parent' model are then analyzed with reference to their underlying mechanisms. The results indicate that too large ENSO amplitude in the CESM is reduced to half by the new AGCM, mainly due to shortwave radiation feedback. Weaker shortwave radiation feedback in the CESM is found to be closely related to the too negative feedbacks of the cloud fraction and cloud liquid amount in the lower layers. © 2016 Royal Meteorological Society."
"36011801900;7007182077;6504311455;6602523027;55463048400;56370934200;35461255500;23995325300;","Atmospheric aerosols local-regional discrimination for a semi-urban area in India",2016,"10.1016/j.atmosres.2015.08.014","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84942354160&doi=10.1016%2fj.atmosres.2015.08.014&partnerID=40&md5=946c9a0e0f0e299734db4fa420b8be2a","In the European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI), measurements were carried out with a sequential filter-based aerosol sampler and on-line instruments for aerosol composition and behaviour at Gual Pahari, close to New Delhi. In fine mode (PM2.5), the secondary organic carbon (SOC) to total organic carbon ratio was 46%. This indicated that condensation of SOC on fine size particles could occur rapidly which may be related to the growth of aerosols and the potential to the size of cloud condensation nuclei in the region. Source region discrimination was improved significantly through coupling conditional probability functions with receptor modelling, and validation through volume size distribution. The air masses from industrial and dense populated regions show a mix of local as well as regional emissions to fine mode aerosols. The back-trajectory analysis captured the long-range transport of sea-salt aerosols enriched with mineral dust. The surface wind directions identified the influence of local emission activities. © 2015 Elsevier B.V."
"15319714800;7007107813;","Investigating the mechanisms of seasonal ENSO phase locking bias in the ACCESS coupled model",2016,"10.1007/s00382-015-2633-y","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957432408&doi=10.1007%2fs00382-015-2633-y&partnerID=40&md5=f040ae47fd113e99f15f0d830910fc77","The mechanisms of coupled model bias in seasonal ENSO phase locking are investigated using versions 1.0 and 1.3 of the CSIRO–BOM ACCESS coupled model (hereafter, ACCESS1.0 and ACCESS1.3, respectively). The two ACCESS coupled models are mostly similar in construction except for some differences, the most notable of which are in the cloud and land surface schemes used in the models. ACCESS1.0 simulates a realistic seasonal phase locking, with the ENSO variability peaking in December as in observations. On the other hand, the simulated ENSO variability in ACCESS1.3 peaks in March, a bias shown to be shared by many other CMIP5 models. To explore the mechanisms of this model bias, we contrast the atmosphere–ocean feedbacks associated with ENSO in both ACCESS model simulations and also compare the key feedbacks with those in other CMIP5 models. We find evidence that the ENSO phase locking bias in ACCESS1.3 is primarily caused by incorrect simulations of the shortwave feedback and the thermocline feedback in this model. The bias in the shortwave feedback is brought about by unrealistic SST–cloud interactions leading to a positive cloud feedback bias that is largest around March, in contrast to the strongest negative cloud feedback found in ACCESS1.0 simulations and observations at that time. The positive cloud feedback bias in ACCESS1.3 is the result of a dominant role played by the low-level clouds in its modeled SST–cloud interactions in the tropical eastern Pacific. Two factors appear to contribute to the dominance of low-level clouds in ACCESS1.3: the occurrence of a stronger mean descending motion bias and, to a lesser extent, a larger mean SST cold bias during March–April in ACCESS1.3 than in ACCESS1.0. A similar association is found between the positive cloud feedback bias and the biases in spring-time mean descending motion and SST for a group of CMIP5 models that show a seasonal phase locking bias similar to ACCESS1.3. Significant differences are also found between the thermocline feedbacks simulated by ACCESS1.0 and ACCESS1.3 that appear to reinforce the seasonal ENSO phase locking bias in the latter model. We discuss a mechanism by which the thermocline feedback differences could arise from atmospheric forcing differences in the two models. © 2015, Springer-Verlag Berlin Heidelberg."
"7006729638;","Summer climate of Madagascar and monsoon pulsing of its vortex",2016,"10.1007/s00703-015-0401-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955384030&doi=10.1007%2fs00703-015-0401-5&partnerID=40&md5=1b0af12196b85a61275f24ee769c3ea5","This study analyzes the climate of Madagascar (12°–26°S, 43°–50°E) and its relation to the Indian Ocean during austral summer (Dec–Mar). Moisture converges onto a standing easterly wave and floods are prevalent in late summer. All-island daytime land temperatures exceed 38 °C in October and are ~4 °C above sea temperatures during summer. Analysis of thermally induced diurnal convection and circulation revealed inflow during the afternoon recirculated from the southeastern mountains and the warm Mozambique Channel. Summer rainfall follows latent and sensible heat flux during the first half of the day, and gains a surplus by evening via thunderstorms over the western plains. At the inter-annual time-scale, 2.3 years oscillations in all-island rainfall appear linked with the stratospheric quasi-biennial oscillation and corresponding 80 Dobson Unit ozone fluctuations during flood events. Wet spells at frequencies from 11–27 days derive from locally-formed tropical cyclones and NW-cloud bands. Flood case studies exhibit moisture recycling in the confluence zone between the sub-tropical anticyclone and the lee-side vortex. Hovmoller analysis of daily rainfall reinforces the concept of local generation and pulsing by cross-equatorial (Indian winter) monsoon flow rather than zonal atmospheric waves. Since the surface water budget is critical to agriculture in Madagascar, this study represents a further step to understand its meso-scale summer climate. © 2015, Springer-Verlag Wien."
"57001793300;7401822381;","Effect of gravity waves on the tropopause temperature, height and water vapor in Tibet from COSMIC GPS Radio Occultation observations",2016,"10.1016/j.jastp.2015.12.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949843701&doi=10.1016%2fj.jastp.2015.12.001&partnerID=40&md5=22e64d074404918ff17d89c1df032fc5","The tropopause plays an important role in climate change, particularly in Tibet with complex topography and climate change system. In this paper, the temperature and height of the Cold Point Tropopause (CPT) in Tibet are obtained and investigated from COSMIC (Constellation Observing System for Meteorology, Ionosphere and Climate) GPS Radio Occultation (RO) during June 2006-Feb 2014, which are compared with Lapse Rate Tropopause (LRT) from Atmospheric Infrared Sounder (AIRS/NASA). Furthermore, the impact of Gravity waves (GW) potential energy (Ep) on the CPT-Temperature, CPT-Height, and the variation of stratospheric water vapor with GW Ep variations are presented. Generally the coldest CPT temperature is in June-July-August (JJA) with -76.5°C, resulting less water vapor into the stratosphere above the cold points. The temperature of the cold point increases up to -69°C during the winter over the Tibetan Plateau (25-40°N, 70-100°E) that leads to increase in water vapor above the cold points (10hPa). Mean vertical fluctuations of temperature are calculated as well as the mean gravity wave potential energy Ep for each month from June 2006 to Feb 2014. Monthly Ep is calculated at 5°×5° grids between 17km and 24km in altitude for the Tibetan Plateau. The Ep raises from 1.83 J/Kg to 3.4 J/Kg from summer to winter with mean Ep of 2.5 J/Kg for the year. The results show that the gravity waves affect the CPT temperature and water vapor concentration in the stratosphere. Water vapor, CPT temperature and gravity wave (Ep) have good correlation with each other above the cold points, and water vapor increases with increasing Ep. © 2015 Elsevier Ltd."
"55969140000;57196203338;7404433688;56082867500;36497832500;","A climatological comparison of column-integrated water vapor for the third-generation reanalysis datasets",2016,"10.1007/s11430-015-5183-6","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955738887&doi=10.1007%2fs11430-015-5183-6&partnerID=40&md5=6fcefc9a8c3ffe0d065162f1786e48d3","The atmospheric reanalysis datasets have been widely used to understand the variability of atmospheric water vapor on various temporal and spatial scales for climate change research. The difference among a variety of reanalysis datasets, however, causes the uncertainty of corresponding results. In this study, the climatology of atmospheric column-integrated water vapor for the period from 2000 to 2012 was compared among three latest third-generation atmospheric reanalyses including European Centre for Medium-range Weather Forecasts Interim Re-Analysis (ERA-Interim), Modern-Era Retrospective Analysis for Research and Applications (MERRA), and Climate Forecast System Reanalysis (CFSR), while possible explanation on the difference between them was given. The results show that there are significant differences among three datasets in the multi-year global distribution, variation of interannual cycle, long-term trend and so on, though high similarity for principal mode describing the variability of water vapor. Over oceans, the characteristics of long-term CWV variability are similar, whereas the main discrepancy among three datasets is located around the equatorial regions of the Intertropical Convergence Zone, the South Pacific Convergence Zone and warm cloud area, which is related with the difference between reanalysis models for the scheme of convective parameterization, the treatment of warm clouds, and the assimilation of satellite-based observations. Moreover, these CWV products are fairly consistent with observations (satellite-based retrievals) for oceans. On the other hand, there are systematic underestimations about 2.5 kg/m2 over lands for all three CWV datasets, compared with radiosonde observations. The difference between models to solve land-atmosphere interaction in complex environment, as well as the paucity in radiosonde observations, leads to significant water vapor gaps in the Amazon Basin of South America, central parts of Africa and some mountainous regions. These results would help better understand the climatology difference among various reanalysis datasets better, and more properly choose water vapor datasets for different research requirements. © 2015, Science China Press and Springer-Verlag Berlin Heidelberg."
"25122625000;7004372407;7006711251;8565323700;7003803916;56878045600;","Precipitation microstructure in different Madden-Julian Oscillation phases over Sumatra",2016,"10.1016/j.atmosres.2015.08.022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84942694039&doi=10.1016%2fj.atmosres.2015.08.022&partnerID=40&md5=56d572c492b3b38d26fd1785bd042442","Intraseasonal variations of precipitation and its microstructure are investigated using measurements of the Equatorial Atmospheric Radar (EAR) facilities at Kototabang, west Sumatra, Indonesia (0.20°S, 100.32°E, 864. m above sea level). Raindrop size distribution (DSD) observations are obtained from a 2D-Video Disdrometer (2DVD) with a near continuous record of operation over eight consecutive years (2003-2010). Precipitation types are classified using 1.3-GHz wind profiler observation, and are partitioned according to active and inactive convective phases of Madden-Julian Oscillation (MJO). It is found that precipitation systems during the inactive phase are more continental in nature than those during the active phase. Cloud propagation from brightness temperature data indicates that Sumatra receives the rainfall mainly from maritime clouds during the active phase, while it is mainly from the continental clouds (land-based convection) during the inactive phase. Other remarkable differences between active and inactive phase precipitation systems are also observed from the vertical structure of precipitation. The precipitation during the inactive phase has deeper storms, a higher reflectivity aloft, more lightning activity and less stratiform characteristics, as compared to the active phase. Assessment of cloud effective radius of the Moderate Resolution Imaging Spectroradiometer (MODIS) data also shows a slight difference in the cloud droplet between the active and the inactive MJO phases. Different convective storms in different MJO phases lead to different DSD characteristics and Z- R relationships. The DSD during the inactive phase tends to have a higher concentration of medium and large-size drops than the active counterpart, consistent with the previous study during the first campaign of Coupling Processes in the Equatorial Atmosphere project. Although the DSD parameters and coefficient of Z- R relationships fall within the range of tropical maritime precipitation, mass-weighted mean diameter (Dm) for the deep convective rains during the inactive phase are somewhat larger than that for maritime and closer to the continental cluster. Therefore, continental-like DSDs are somewhat dominant during the inactive phase, consistent with the intraseasonal variation of precipitation structure. The causative processes of the observed difference in the DSD for the two phases have also been discussed with the help of satellite and radar data. Evaporation and updraft associated with the intense convection during the inactive phase seem to eliminate the small-sized drops from the spectra. Finally, radar reflectivity during the inactive phase is larger than that during the active MJO phase, at the same rainfall rate. This condition can limit the accuracy of radar-derived rainfall estimates for the tropics when applying a single Z- R relation to the two MJO phases, particularly for deep convective rains. © 2015 Elsevier B.V."
"35735614000;23394244800;55729060300;56282814800;57201360847;55503297500;55257549400;57206859945;","Particle growth and variation of cloud condensation nucleus activity on polluted days with new particle formation: A case study for regional air pollution in the PRD region, China",2016,"10.4209/aaqr.2015.06.0381","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961348588&doi=10.4209%2faaqr.2015.06.0381&partnerID=40&md5=fc0043ed1c3c0387f8905842c4005012","New particle formation (NPF) events on polluted days at a regional supersite in the Pearl River Delta (PRD) region and its impact on the abundance and properties of cloud condensation nuclei (CCN) were investigated. Nucleation and subsequent significant growth of nanoparticles on a regional scale was observed and representative events on 2 and 6 October 2013 were chosen in this study. The measurements showed that the primary components of the particles were sulfate, ammonium, and organics as they were added continuously to secondary aerosol mass and that particles show inversion from growth to shrink if the particles comprise primarily of organics due to evaporation of semi-volatile species under favorable meteorological conditions. The effective hygroscopicity parameter κ of fine particles on 2 October composed of sulfate, nitrate and ammonium (κ = 0.26-0.42) was larger than that of fine particles on 6 October containing more organics (κ = 0.19-0.36). Particles in the nucleation mode were observed to grow rapidly to the CCN sizes and dominate the CCN number concentrations at a water vapor supersaturation (S) over 0.46%. At an S range of 0.26-0.86%, the CCN number concentrations reached maximum values of (1.3-2.6) × 104 cm-3 after the NPF event on 2 October. The sulfate component in the particles was found to increase significantly, about 50% higher than that before NPF. Results from events on 6 October showed a significant increase of the organic component and the CCN number concentrations after the NPF event were comparable or slightly lower than those before the event. Nevertheless, the average CCN number concentrations scaled with EC mass concentration with S over 0.46% in the daytime of 2 and 6 October were significantly higher than those on a non-NPF event day. © Taiwan Association for Aerosol Research."
"6603738903;56013709700;55989808400;35607003400;","Molecular and iridescent feather reflectance data reveal recent genetic diversification and phenotypic differentiation in a cloud forest hummingbird",2016,"10.1002/ece3.1950","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958945361&doi=10.1002%2fece3.1950&partnerID=40&md5=86fb4d10aa45bf59fa128f6e3125f71a","The present day distribution and spatial genetic diversity of Mesoamerican biota reflects a long history of responses to habitat change. The hummingbird Lampornis amethystinus is distributed in northern Mesoamerica, with geographically disjunct populations. Based on sampling across the species range using mitochondrial DNA (mtDNA) sequences and nuclear microsatellites jointly analysed with phenotypic and climatic data, we (1) test whether the fragmented distribution is correlated with main evolutionary lineages, (2) assess body size and plumage color differentiation of populations in geographic isolation, and (3) evaluate a set of divergence scenarios and demographic patterns of the hummingbird populations. Analysis of genetic variation revealed four main groups: blue-throated populations (Sierra Madre del Sur); two groups of amethyst-throated populations (Trans-Mexican Volcanic Belt and Sierra Madre Oriental); and populations east of the Isthmus of Tehuantepec (IT) with males showing an amethyst throat. The most basal split is estimated to have originated in the Pleistocene, 2.39-0.57 million years ago (MYA), and corresponded to groups of populations separated by the IT. However, the estimated recent divergence time between blue- and amethyst-throated populations does not correspond to the 2-MY needed to be in isolation for substantial plumage divergence, likely because structurally iridescent colors are more malleable than others. Results of species distribution modeling and Approximate Bayesian Computation analysis fit a model of lineage divergence west of the Isthmus after the Last Glacial Maximum (LGM), and that the species' suitable habitat was disjunct during past and current conditions. These results challenge the generality of the contraction/expansion glacial model to cloud forest-interior species and urges management of cloud forest, a highly vulnerable ecosystem to climate change and currently facing destruction, to prevent further loss of genetic diversity or extinction. © 2016 Published by John Wiley & Sons Ltd."
"56329651900;56820509800;36110342400;55490127200;36164002200;56315540600;57203140102;","Spatial distribution of forest aboveground biomass in China: Estimation through combination of spaceborne lidar, optical imagery, and forest inventory data",2016,"10.1016/j.rse.2015.12.002","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949490566&doi=10.1016%2fj.rse.2015.12.002&partnerID=40&md5=292dba9536ea0f83de6df408415c3120","The global forest ecosystem, which acts as a large carbon sink, plays an important role in modeling the global carbon balance. An accurate estimation of the total forest carbon stock in the aboveground biomass (AGB) is therefore necessary for improving our understanding of carbon dynamics, especially against the background of global climate change. The forest area of China is among the top five globally. However, because of limitations in forest AGB mapping methods and the availability of ground inventory data, there is still a lack in the nationwide wall-to-wall forest AGB estimation map for China. In this study, we collected over 8000 ground inventory records from published literatures, and developed an AGB mapping method using a combination of these ground inventory data, Geoscience Laser Altimeter System (GLAS)/Ice, Cloud, and Land Elevation Satellite (ICESat) data, optical imagery, climate surfaces, and topographic data. An uncertainty field model was introduced into the forest AGB mapping procedure to minimize the influence of plot location uncertainty. Our nationwide wall-to-wall forest AGB mapping results show that the forest AGB density in China is 120 Mg/ha on average, with a standard deviation of 61 Mg/ha. Evaluation with an independent ground inventory dataset showed that our proposed method can accurately map wall-to-wall forest AGB across a large landscape. The adjusted coefficient of determination (R2) and root-mean-square error between our predicted results and the validation dataset were 0.75 and 42.39 Mg/ha, respectively. This new method and the resulting nationwide wall-to-wall forest AGB map will help to improve the accuracy of carbon dynamic predictions in China. © 2015 Elsevier Inc."
"16551540700;56992244500;13608654700;7201381456;","Transport characteristics of Chinese haze over Northern Taiwan in winter, 2005-2014",2016,"10.1016/j.atmosenv.2015.11.043","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949229451&doi=10.1016%2fj.atmosenv.2015.11.043&partnerID=40&md5=a8aa5588720ee5f920a2d591af0c5868","Haze over east China has been extensively studied, but its impacts on downwind areas remain unclear. In this study, we applied long-term (9 yr) air quality, meteorological, and ground-based remote sensing data for investigating the transported haze events over Northern Taiwan in winter. Thirty-six haze events were identified using a statistical method and information pertaining to wind direction and episode duration. In contrast to haze events over China, the transported haze exhibits low relative humidity (approximately 70%) and high wind speed (approximately 5 m s-1) and is associated with a migrating high-pressure system. The mass concentration of fine particulate matter (PM2.5) for the haze events was 57.1 ± 13.6 μg m-3, nearly four times higher than that of the background (13.7 ± 7.4 μg m-3). Such high PM levels persisted for 120 h in winter. Back trajectory analysis suggests that the haze particles were transported from the east coast of China, particularly from the Yangtze River Delta (YRD) area with a traveling time of nearly 28 h. Lidar observations clarify that the Chinese haze was transported to Northern Taiwan and accompanied by low clouds and a temperature inversion layer, which confined the particles to a height of less than 1 km. Moreover, a relatively high PM2.5 concentration (65.0 μg m-3) was observed when air mass stagnated over YRD before advancing to Taiwan. This scenario, most frequently seen in the winter of 2013, resulted in the highest historical PM2.5 concentration (approximately 77.2 μg m-3). We propose that the heavy haze year is primarily attributable to synoptic weather variability and less to climate. © 2015 Elsevier Ltd."
"36547674200;57208346904;7101912546;7003938788;14038431700;","Simulation of seasonal US precipitation and temperature by the nested CWRF-ECHAM system",2016,"10.1007/s00382-015-2619-9","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957426330&doi=10.1007%2fs00382-015-2619-9&partnerID=40&md5=b545f87c9bbe370983d21018fe5ccd9a","This study investigates the refined simulation skill that results when the regional Climate extension of the Weather Research and Forecasting (CWRF) model is nested in the ECMWF Hamburg version 4.5 (ECHAM) atmospheric general circulation model over the United States during 1980–2009, where observed sea surface temperatures are used in both models. Over the contiguous US, for each of the four seasons from winter to fall, CWRF reduces the root mean square error of the ECHAM seasonal mean surface air temperature simulation by 0.19, 0.82, 2.02 and 1.85 °C, and increases the equitable threat score of seasonal mean precipitation by 0.18, 0.11, 0.09 and 0.12. CWRF also simulates much more realistically daily precipitation frequency and heavy precipitation events, typically over the Central Great Plains, Cascade Mountains and Gulf Coast States. These CWRF skill enhancements are attributed to the increased spatial resolution and physics refinements in representing orographic, terrestrial hydrology, convection, and cloud-aerosol-radiation effects and their interactions. Empirical orthogonal function analysis of seasonal mean precipitation and surface air temperature interannual variability shows that, in general, CWRF substantially improves the spatial distribution of both quantities, while temporal evolution (i.e. interannual variability) of the first 3 primary patterns is highly correlated with that of the driving ECHAM (except for summer precipitation), and they both have low temporal correlations against observations. During winter, when large-scale forcing dominates, both models also have similar responses to strong ENSO signals where they successfully capture observed precipitation composite anomalies but substantially fail to reproduce surface air temperature anomalies. When driven by the ECMWF Reanalysis Interim, CWRF produces a very realistic interannual evolution of large-scale precipitation and surface air temperature patterns where the temporal correlations with observations are significant. These results indicate that CWRF can greatly improve mesoscale regional climate structures but it cannot change interannual variations of the large-scale patterns, which are determined by the driving lateral boundary conditions. © 2015, Springer-Verlag Berlin Heidelberg."
"57004641500;14064254400;7409462943;25958069700;35786777300;57004299700;","Glacier changes since the early 1960s, eastern Pamir, China",2016,"10.1007/s11629-014-3172-4","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957880754&doi=10.1007%2fs11629-014-3172-4&partnerID=40&md5=318938bb63e365646b834420420d2827","Glaciers in the eastern Pamir are important for water resources and the social and economic development of the region. In the last 50 years, these glaciers have shrunk and lost ice mass due to climate change. In order to understand recent glacier dynamics in the region, a new inventory was compiled from Landsat TM/ETM+ images acquired in 2009, free of clouds and with minimal snow cover on the glacierized mountains. The first glacier inventory of the area was also updated by digitizing glacier outlines from topographical maps that had been modified and verified using aerial photographs. Total glacier area decreased by 10.8%±1.1%, mainly attributed to an increase in air temperature, although precipitation, glacier size and topographic features also combined to affect the general shrinkage of the glaciers. The 19.3-21.4 km3 estimated glacier mass loss has contributed to an increase in river runoff and water resources. © 2016, Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag Berlin Heidelberg."
"7103101609;55735405000;56243733200;56217012400;41661824500;55490304500;55880113000;55925226900;54889019300;6603934961;","Experimental determination and theoretical framework of kinetic fractionation at the water vapour-ice interface at low temperature",2016,"10.1016/j.gca.2015.11.009","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84948434733&doi=10.1016%2fj.gca.2015.11.009&partnerID=40&md5=17d962a2b8367e5369aa610b6479f51f","Water isotopes are commonly used for climate reconstruction from ice cores. The different heavy isotopes of water such as H218O, H217O or HDO give information about local temperature but also temperature and humidity of water vapour sources. Quantification of these parameters relies on the good knowledge of equilibrium and kinetic isotopic fractionation at each step of the water cycle. One of the strongest limitations when interpreting water isotopes in remote Antarctic ice cores is the formulation of the isotopic fractionation at solid condensation (vapour to ice). This classical formulation also implies a good knowledge of coefficients for equilibrium fractionation and water vapour diffusion in air as well as supersaturation in clouds. The uncertainties associated with these different parameters make the formulation of isotopic fractionation at solid condensation only empirical.Here, we make use (1) of recent development in the measurements of water isotopes in the water vapour through infra-red spectroscopy and (2) of the possibility to measure accurately 17O-excess of water to test the classical formulation and parameterization of isotopic fractionation at solid condensation. A first experiment involving very strong supersaturation evidences a strong kinetic effect on 17O-excess at solid condensation, similar to d-excess. It also shows the limits of the classical formulation of water isotopic fractionation during solid condensation estimation at very low temperature. A second experiment performed in a cloud chamber under controlled conditions uses cavity ring down spectrometers (CRDS) to determine the spatial variability of water vapour isotopic composition due to diffusion (kinetic effect) during solid condensation. The spatial variability of water vapour isotopic composition can be relatively well reproduced by the resolution of diffusion toward a cold plate. This preliminary study opens new perspectives to revisit the classical formulation of water isotopic fractionation during solid condensation at very low temperature. © 2015 Elsevier Ltd."
"57079115600;56211796800;","Towards climatological study on the characteristics of aerosols in Central Africa and Mediterranean sites",2016,"10.1016/j.jastp.2016.01.011","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955598866&doi=10.1016%2fj.jastp.2016.01.011&partnerID=40&md5=d4b1152a654f222d8b3ed33d2fe3251c","The atmosphere contains molecules, clouds and aerosols that are sub-millimeter particles having a large variability in size, shape, chemical composition, lifetime and contents. The aerosols concentration depends greatly on the geographical situation, meteorological and environmental conditions, which makes aerosol climatology difficult to assess. Setting up a solar photometer (automatic, autonomous and portable instrument) on a given site allows carrying out the necessary measurements for aerosol characterization. The particle microphysical and optical properties are obtained from photometric measurements. The objective of this study is to analyze the spatial variability of aerosol optical thickness (AOT) in several Mediterranean regions and Central Africa, we considered a set of simultaneous data in the AErosol RObotic NETwork (AERONET) from six sites, two of which are located in Central Africa (Banizoumbou and Zinder Airport) and the rest are Mediterranean sites (Barcelona, Malaga, Lampedusa, and Forth Crete). The results have shown that the physical properties of aerosols are closely linked to the climate nature of the studied site. The optical thickness, single scattering albedo and aerosols size distribution can be due to the aging of the dust aerosol as they are transported over the Mediterranean basin. © 2016 Elsevier Ltd."
"56740064100;55673891100;57105159700;57205352120;56739712900;57143396100;56740231900;55673409800;55672875700;57104262200;","Analysis of the origin of peak aerosol optical depth in springtime over the Gulf of Tonkin",2016,"10.1016/j.jes.2015.10.026","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960814611&doi=10.1016%2fj.jes.2015.10.026&partnerID=40&md5=63577ccafaf808a6c4b4caca7b8cc2a1","By aggregating MODIS (moderate-resolution imaging spectroradiometer) AOD (aerosol optical depth) and OMI (ozone monitoring instrument) UVAI (ultra violet aerosol index) datasets over 2010-2014, it was found that peak aerosol loading in seasonal variation occurred annually in spring over the Gulf of Tonkin (17-23°N, 105-110°E). The vertical structure of the aerosol extinction coefficient retrieved from the spaceborne lidar CALIOP (cloud-aerosol lidar with orthogonal polarization) showed that the springtime peak AOD could be attributed to an abrupt increase in aerosol loading between altitudes of 2 and 5 km. In contrast, aerosol loading in the low atmosphere (below 1 km) was only half of that in winter. Wind fields in the low and high atmosphere exhibited opposite transportation patterns in spring over the Gulf of Tonkin, implying different sources for each level. By comparing the emission inventory of anthropogenic sources with biomass burning, and analyzing the seasonal variation of the vertical structure of aerosols over the Northern Indo-China Peninsula (NIC), it was concluded that biomass burning emissions contributed to high aerosol loading in spring. The relatively high topography and the high surface temperature in spring made planetary boundary layer height greater than 3 km over NIC. In addition, small-scale cumulus convection frequently occurred, facilitating pollutant rising to over 3 km, which was a height favoring long-range transport. Thus, pollutants emitted from biomass burning over NIC in spring were raised to the high atmosphere, then experienced long-range transport, leading to the increase in aerosol loading at high altitudes over the Gulf of Tonkin during spring. © 2015."
"57199744001;57200058609;","A solely radiance-based spectral angular distribution model and its application in deriving clear-sky spectral fluxes over tropical oceans",2016,"10.1007/s00376-015-5040-8","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84952047620&doi=10.1007%2fs00376-015-5040-8&partnerID=40&md5=e4cb82ccc26edda306631826f941df7d","The radiation budget at the top of the atmosphere plays a critical role in climate research. Compared to the broadband flux, the spectrally resolved outgoing longwave radiation or flux (OLR), with rich atmospheric information in different bands, has obvious advantages in the evaluation of GCMs. Unlike methods that need auxiliary measurements and information, here we take atmospheric infrared sounder (AIRS) observations as an example to build a self-consistent algorithm by an angular distribution model (ADM), based solely on radiance observations, to estimate clear-sky spectrally resolved fluxes over tropical oceans. As the key step for such an ADM, scene type estimations are obtained from radiance and brightness temperature in selected AIRS channels. Then, broadband OLR as well as synthetic spectral fluxes are derived by the spectral ADM and validated using both synthetic spectra and CERES (Clouds and the Earth’s Radiant Energy System) observations. In most situations, the mean OLR differences between the spectral ADM products and the CERES observations are within ±2 W m-2, which is less than 1% of the typical mean clear-sky OLR over tropical oceans. The whole algorithm described in this study can be easily extended to other similar hyperspectral radiance measurements. © 2016, Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg."
"56495287900;26530857000;7004593510;26027623800;24340667100;56383707900;6505637161;55871322800;8084443000;6602922400;14035386400;57205842560;7003334425;","Size distribution and optical properties of mineral dust aerosols transported in the western Mediterranean",2016,"10.5194/acp-16-1081-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956964893&doi=10.5194%2facp-16-1081-2016&partnerID=40&md5=07d2c8a90e35d7f52ee07ae27f4eed83","This study presents in situ aircraft measurements of Saharan mineral dust transported over the western Mediterranean basin in June-July 2013 during the ChArMEx/ADRIMED (the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) airborne campaign. Dust events differing in terms of source region (Algeria, Tunisia and Morocco), time of transport (1-5 days) and height of transport were sampled. Mineral dust were transported above the marine boundary layer, which conversely was dominated by pollution and marine aerosols. The dust vertical structure was extremely variable and characterized by either a single layer or a more complex and stratified structure with layers originating from different source regions. Mixing of mineral dust with pollution particles was observed depending on the height of transport of the dust layers. Dust layers carried a higher concentration of pollution particles below 3 km above sea level (a.s.l.) than above 3 km a.s.l., resulting in a scattering Ångström exponent up to 2.2 below 3 km a.s.l. However, the optical properties of the dust plumes remained practically unchanged with respect to values previously measured over source regions, regardless of the altitude. Moderate absorption of light by the dust plumes was observed with values of aerosol single scattering albedo at 530 nm ranging from 0.90 to 1.00. Concurrent calculations from the aerosol chemical composition revealed a negligible contribution of pollution particles to the absorption properties of the dust plumes that was due to a low contribution of refractory black carbon in regards to the fraction of dust and sulfate particles. This suggests that, even in the presence of moderate pollution, likely a persistent feature in the Mediterranean, the optical properties of the dust plumes could be assumed similar to those of native dust in radiative transfer simulations, modelling studies and satellite retrievals over the Mediterranean. Measurements also showed that the coarse mode of mineral dust was conserved even after 5 days of transport in the Mediterranean, which contrasts with the gravitational depletion of large particles observed during the transport of dust plumes over the Atlantic. Simulations with the WRF mesoscale meteorological model highlighted a strong vertical turbulence within the dust layers that could prevent deposition of large particles during their atmospheric transport. This has important implications for the dust radiative effects due to surface dimming, atmospheric heating and cloud formation. The results presented here add to the observational data set necessary for evaluating the role of mineral dust on the regional climate and rainfall patterns in the western Mediterranean basin and understanding their atmospheric transport at global scale. © 2016 Author(s)."
"55972773600;55718857500;23161713000;36622801400;24759264100;7404118434;55432775500;55433117900;23035769400;6603253360;","Characteristics of formation and growth of atmospheric nanoparticles observed at four regional background sites in Korea",2016,"10.1016/j.atmosres.2015.08.020","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84942543475&doi=10.1016%2fj.atmosres.2015.08.020&partnerID=40&md5=df16a2a76f8117c231069dce6f1d5ab6","Measurements of the number concentration and size distribution of atmospheric nanoparticles were conducted at four sites on the west coast of the Korean Peninsula by using identical scanning mobility particle sizers (SMPSs) in October 2012. The new particle formation and subsequent growth (NPF) of atmospheric nanoparticles, which were identified by the cyclostationary empirical orthogonal function (CSEOF) analysis technique, was observed on 11 out of 21. days at the Baengnyeong-do Comprehensive Monitoring Observatory (BCMO); and on 10 out of 21. days at the Korea Global Atmosphere Watch Center (KGAWC) from October 9 to 29, 2012. We also observed NPF events for 9 out of 21. days at both the Gosan Climate Observatory (GCO) and the Jeju Comprehensive Monitoring Observatory (JCMO). During the study period, NPF was simultaneously observed for five days at all four sites, which indicates that the NPF event had a spatial extent of at least 540. km. A cold, dry and cloud-free continental air mass originated from northern China, formed favorable environmental conditions (e.g., increasing solar insolation at the surface) on simultaneous NPF at the four sites. These synoptic weather patterns were closely associated with an extraordinary typhoon passing over the south of Japan. The mean values of particle formation rates at BCMO (1.26cm-3s-1) and KGAWC (1.49cm-3s-1) were relatively higher than those at GCO (0.39cm-3s-1) and JCMO (0.74cm-3s-1), however, the growth rate showed a similar level among four sites. An increase in the spatial homogeneity and inter-site correlation of atmospheric particles among the four sites was apparent for small particles (diameter&lt;30nm) on simultaneous NPF event days. © 2015 Elsevier B.V."
"55914512600;56375050900;57214142405;","Satellite and ground-based remote sensing of aerosols during intense haze event of October 2013 over lahore, Pakistan",2016,"10.1007/s13143-015-0084-3","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955614243&doi=10.1007%2fs13143-015-0084-3&partnerID=40&md5=cfa5f15f0f5797e72d20d0e4a04416ed","Due to increase in population and economic development, the mega-cities are facing increased haze events which are causing important effects on the regional environment and climate. In order to understand these effects, we require an in-depth knowledge of optical and physical properties of aerosols in intense haze conditions. In this paper an effort has been made to analyze the microphysical and optical properties of aerosols during intense haze event over mega-city of Lahore by using remote sensing data obtained from satellites (Terra/Aqua Moderate-resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO)) and ground based instrument (AErosol RObotic NETwork (AERONET)) during 6-14 October 2013. The instantaneous highest value of Aerosol Optical Depth (AOD) is observed to be 3.70 on 9 October 2013 followed by 3.12 on 8 October 2013. The primary cause of such high values is large scale crop residue burning and urban-industrial emissions in the study region. AERONET observations show daily mean AOD of 2.36 which is eight times higher than the observed values on normal day. The observed fine mode volume concentration is more than 1.5 times greater than the coarse mode volume concentration on the high aerosol burden day. We also find high values (~0.95) of Single Scattering Albedo (SSA) on 9 October 2013. Scatter-plot between AOD (500 nm) and Angstrom exponent (440-870 nm) reveals that biomass burning/urban-industrial aerosols are the dominant aerosol type on the heavy aerosol loading day over Lahore. MODIS fire activity image suggests that the areas in the southeast of Lahore across the border with India are dominated by biomass burning activities. A Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model backward trajectory showed that the winds at 1000 m above the ground are responsible for transport from southeast region of biomass burning to Lahore. CALIPSO derived sub-types of aerosols with vertical profile taken on 10 October 2013 segregates the wide spread aerosol burden as smoke, polluted continental and dust aerosols. © 2016, Korean Meteorological Society and Springer Science+Business Media Dordrecht."
"36024584700;6603585615;7404462897;57206763390;55973527200;7006057354;7007017266;55332194700;57031859900;8359591200;56214091200;6602356428;6603178707;6506458269;16834406100;55659925600;7004643405;57203776263;6602221672;7006709050;7003452377;","Airborne measurements and emission estimates of greenhouse gases and other trace constituents from the 2013 California Yosemite Rim wildfire",2016,"10.1016/j.atmosenv.2015.12.038","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84952690483&doi=10.1016%2fj.atmosenv.2015.12.038&partnerID=40&md5=19ecc7eb2ff8df5b1676b47fd807a3ab","This paper presents airborne measurements of multiple atmospheric trace constituents including greenhouse gases (such as CO2, CH4, O3) and biomass burning tracers (such as CO, CH3CN) downwind of an exceptionally large wildfire. In summer 2013, the Rim wildfire, ignited just west of the Yosemite National Park, California, and burned over 250,000 acres of the forest during the 2-month period (17 August to 24 October) before it was extinguished. The Rim wildfire plume was intercepted by flights carried out by the NASA Ames Alpha Jet Atmospheric eXperiment (AJAX) on 29 August and the NASA DC-8, as part of SEAC4RS (Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys), on 26 and 27 August during its intense, primary burning period. AJAX revisited the wildfire on 10 September when the conditions were increasingly smoldering, with slower growth. The more extensive payload of the DC-8 helped to bridge key measurements that were not available as part of AJAX (e. g. CO). Data analyses are presented in terms of emission ratios (ER), emission factors (EF) and combustion efficiency and are compared with previous wildfire studies. ERs were 8.0 ppb CH4 (ppm CO2)-1 on 26 August, 6.5 ppb CH4 (ppm CO2)-1 on 29 August and 18.3 ppb CH4 (ppm CO2)-1 on 10 September 2013. The increase in CH4 ER from 6.5 to 8.0 ppb CH4 (ppm CO2)-1 during the primary burning period to 18.3 ppb CH4 (ppm CO2)-1 during the fire's slower growth period likely indicates enhanced CH4 emissions from increased smoldering combustion relative to flaming combustion. Given the magnitude of the Rim wildfire, the impacts it had on regional air quality and the limited sampling of wildfire emissions in the western United States to date, this study provides a valuable dataset to support forestry and regional air quality management, including observations of ERs of a wide number of species from the Rim wildfire. © 2015 Elsevier Ltd."
"56479176700;7005920812;","A flexible importance sampling method for integrating subgrid processes",2016,"10.5194/gmd-9-413-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956605914&doi=10.5194%2fgmd-9-413-2016&partnerID=40&md5=fd253ec83973c9ebb5a6427d892b74b5","Numerical models of weather and climate need to compute grid-box-averaged rates of physical processes such as microphysics. These averages are computed by integrating subgrid variability over a grid box. For this reason, an important aspect of atmospheric modeling is spatial integration over subgrid scales. The needed integrals can be estimated by Monte Carlo integration. Monte Carlo integration is simple and general but requires many evaluations of the physical process rate. To reduce the number of function evaluations, this paper describes a new, flexible method of importance sampling. It divides the domain of integration into eight categories, such as the portion that contains both precipitation and cloud, or the portion that contains precipitation but no cloud. It then allows the modeler to prescribe the density of sample points within each of the eight categories. The new method is incorporated into the Subgrid Importance Latin Hypercube Sampler (SILHS). The resulting method is tested on drizzling cumulus and stratocumulus cases. In the cumulus case, the sampling error can be considerably reduced by drawing more sample points from the region of rain evaporation. © 2016 Author(s)."
"57090458900;57090955400;7005304841;7801595201;26647270000;7006634316;7202967741;57090108000;13406672500;","Vertical profiles of optical and microphysical particle properties above the northern Indian Ocean during CARDEX 2012",2016,"10.5194/acp-16-1045-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956694753&doi=10.5194%2facp-16-1045-2016&partnerID=40&md5=25944d0b2104a05527ff7bca9b012c6e","A detailed analysis of optical and microphysical properties of aerosol particles during the dry winter monsoon season above the northern Indian Ocean is presented. The Cloud Aerosol Radiative Forcing Experiment (CARDEX), conducted from 16 February to 30 March 2012 at the Maldives Climate Observatory on Hanimaadhoo island (MCOH) in the Republic of the Maldives, used autonomous unmanned aerial vehicles (AUAV) to perform vertical in situ measurements of particle number concentration, particle number size distribution as well as particle absorption coefficients. These measurements were used together with surface-based Mini Micro Pulse Lidar (MiniMPL) observations and aerosol in situ and off-line measurements to investigate the vertical distribution of aerosol particles.Air masses were mainly advected over the Indian subcontinent and the Arabian Peninsula. The mean surface aerosol number concentration was 1717 ± 604 cm-3 and the highest values were found in air masses from the Bay of Bengal and Indo-Gangetic Plain (2247 ± 370 cm-3). Investigations of the free tropospheric air showed that elevated aerosol layers with up to 3 times higher aerosol number concentrations than at the surface occurred mainly during periods with air masses originating from the Bay of Bengal and the Indo-Gangetic Plain. This feature is different compared to what was observed during the Indian Ocean Experiment (INDOEX) conducted in winter 1999, where aerosol number concentrations generally decreased with height. In contrast, lower particle absorption at the surface (abs(520 nm) Combining double low line 8.5 ± 4.2 Wm) was found during CARDEX compared to INDOEX 1999.Layers with source region specific single-scattering albedo (SSA) values were derived by combining vertical in situ particle absorption coefficients and scattering coefficients calculated with Mie theory. These SSA layers were utilized to calculate vertical particle absorption profiles from MiniMPL profiles. SSA surface values for 550 nm for dry conditions were found to be 0.94 ± 0.02 and 0.91 ± 0.02 for air masses from the Arabian Sea (and Middle East countries) and India (and Bay of Bengal), respectively. Lidar-derived particle absorption coefficient profiles showed both a similar magnitude and structure as the in situ profiles measured with the AUAV. However, primarily due to insufficient accuracy in the SSA estimates, the lidar-derived absorption coefficient profiles have large uncertainties and are generally weakly correlated to vertically in situ measured particle absorption coefficients.Furthermore, the mass absorption efficiency (MAE) for the northern Indian Ocean during the dry monsoon season was calculated to determine equivalent black carbon (EBC) concentrations from particle absorption coefficient measurements. A mean MAE of 11.6 and 6.9 m2 gg'1 for 520 and 880 nm, respectively, was found, likely representing internally mixed BC containing particles. Lower MAE values for 880 and 520 nm were found for air masses originating from dust regions such as the Arabian Peninsula and western Asia (MAE(880 nm) Combining double low line 5.6 m2 g-1, MAE(520 nm) Combining double low line 9.5 m2 gg1) or from closer source regions as southern India (MAE(880 nm) Combining double low line 4.3 m2 gg1, MAE(520 nm) Combining double low line 7.3 m2 ). © 2016 Author(s) . CC Attribution 3.0 License."
"56193595700;56984982400;56984920900;","Determination of surfactants and levoglucosan from selected vegetation by spectroscopic colorimetric method",2016,"10.1080/03067319.2015.1114110","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957841633&doi=10.1080%2f03067319.2015.1114110&partnerID=40&md5=1651ebd0e4034eaba0ded8a418bc0247","Vegetation is one of the natural sources which contribute to the amount of surface active agent into the environment. It is believed that surfactants can be derived from various kinds of sources such as biomass burning or soil and these excessive level of surfactants emitted into the atmosphere can influence both cloud formation and climate. The objective of this study was to determine the concentration of both anionic and cationic surfactants as well as levoglucosan from vegetation and soot and at different weather conditions around the tin mine lakes environment. The samples were prepared by cutting several parts of tropical plant species, namely Cinnamomum Iners, Gliricidia Sepium and Hopea Odorata, which were mainly leaves and stems. After that, samples were allowed to dry in an oven at a temperature of 40°C for 2 h. The concentrations of levoglucosan and surfactant such as methylene blue active substance (MBAS) and disulphine blue active substance (DBAS) were analysed through the colorimetric method. The results showed that higher concentrations for both anionic and cationic surfactants were found in C. Iners leaves which give the concentrations of 86.92 ± 38.99 and 22.33 ± 10.59 µg/g. It was noted that the concentrations of anionic and cationic surfactants in this research were correlated to each other, indicating the possibility of similar sources that affect both levels of surfactants in the vegetation. In addition, the highest level of levoglucosan was dominated by the leaves from G. Sepium species with the concentration of 25.62 ± 12.65 mg/g, respectively. A positive significant correlation (r = 0.8447, 0.8355 and p = 0.0001 < 0.05) between anionic surfactants and levoglucosan was also discovered in this study. © 2015 Taylor & Francis."
"56543138800;57202142004;6701313597;7003427471;7003430284;57208121047;56592889000;36194896400;56452429200;7004027519;16444265000;8058018000;57190004884;55730602600;57203231853;","Ship emissions measurement in the Arctic from plume intercepts of the Canadian Coast Guard Amundsen icebreaker from the Polar 6 aircraft platform",2016,"10.5194/acp-2015-1032","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987869119&doi=10.5194%2facp-2015-1032&partnerID=40&md5=990d12dd32d7e690d88dd72e5a158c6e","Decreasing sea ice and increasing marine navigability in northern latitudes have changed Arctic ship traffic patterns in recent years and are predicted to increase annual ship traffic in the Arctic in the future. Development of effective regulations to manage environmental impacts of shipping requires an understanding of ship emissions and atmospheric processing in the Arctic environment. As part of the summer 2014 NETCARE (Network on Climate and Aerosols) campaign, the plume dispersion and gas and particle emission factors of emissions originating from the Canadian Coast Guard Amundsen icebreaker operating near Resolute Bay, NU, Canada have been investigated. The Amundsen burnt distillate fuel with 1.5 wt % sulfur. Emissions were studied via plume intercepts using aircraft measurements, an analytical plume dispersion model, and using the FLEXPART-WRF Lagrangian particle dispersion model. The first plume intercepts by research aircraft were carried out on 19 July 2014 during the operation of the Amundsen in the open water. The second and third plume intercept measurements were carried out on 20 and 21 July 2014 when the Amundsen had reached the ice edge and operated under icebreaking conditions. Typical of Arctic marine navigation, the engine load was low compared to cruising conditions for all of the plume intercepts. The measured species included mixing ratios of CO2, NOx, CO, SO2, particle number concentration (CN), refractory Black Carbon (rBC), and Cloud Condensation Nuclei (CCN). The results were compared to similar experimental studies in mid latitudes. Plume expansion rates (γ) were calculated using the analytical model and found to be γ = 0.75 ± 0.80, 0.93 ± 0.37, and 1.19 ± 0.39 for plumes 1, 2, and 3, respectively. These rates are smaller than prior studies conducted at mid latitudes, likely due to polar boundary layer dynamics, including reduced turbulent mixing compared to mid latitudes. All emission factors were in agreement with prior observations at low engine loads in mid latitudes. Icebreaking increased the NOx emission factor from EFNOx = 22.3 ± 8.0 to 57.8 ± 11.0 and 65.8 ± 4.0 g kg - diesel-1 for plumes 1, 2, and 3, likely due to change in combustion temperatures. The CO emission factor was EFCO = 6.4 ± 11.7, 6.8 ± 2.2 and 5.0 ± 1.0 g kg - diesel-1 for plumes 1, 2, and 3. The rBC emission factor was EFrBC = 0.20 ± 0.04 and 0.25 ± 0.12 g kg - diesel-1 for plumes 1 and 2. The CN emission factor was reduced while icebreaking from EFCPC = 1.96 ± 0.41 to 0.43 ± 0.11 and 0.47 ± 0.04 × 1016 kg - diesel-1 for plumes 1, 2, and 3. At 0.6 % supersaturation, the CCN emission factor was lower than observations in mid latitudes at low engine loads with EFCCN = 1.63 ± 0.41 to 1.06 ± 0.32 and 0.28 ± 0.07 × 1014 kg - diesel-1 for plumes 1, 2, and 3. © Author(s) 2016."
"7103246957;36895628100;","Annual climatology of the diurnal cycle on the Canadian prairies",2016,"10.3389/feart.2016.00001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994589873&doi=10.3389%2ffeart.2016.00001&partnerID=40&md5=d6a4a88eda04e497dd4481f806d717c1","We show the annual climatology of the diurnal cycle, stratified by opaque cloud, using the full hourly resolution of the Canadian Prairie data. The opaque cloud field itself has distinct cold and warm season diurnal climatologies; with a near-sunrise peak of cloud in the cold season and an early afternoon peak in the warm season. There are two primary climate states on the Canadian Prairies, separated by the freezing point of water, because a reflective surface snow cover acts as a climate switch. Both cold and warm season climatologies can be seen in the transition months of November, March, and April with a large difference in mean temperature. In the cold season with snow, the diurnal ranges of temperature and relative humidity increase quasi-linearly with decreasing cloud, and increase from December to March with increased solar forcing. The warm season months, April to September, show a homogeneous coupling to the cloud cover, and a diurnal cycle of temperature and humidity that depends only on net longwave. Our improved representation of the diurnal cycle shows that the warmseason coupling between diurnal temperature range and net longwave is weakly quadratic through the origin, rather than the linear coupling shown in earlier papers. We calculate the conceptually important 24-h imbalances of temperature and relative humidity (and other thermodynamic variables) as a function of opaque cloud cover. In the warmseason under nearly clear skies, there is a warming of +2° C and a drying of −6% over the 24-h cycle, which is about 12% of their diurnal ranges. We summarize results on conserved variable diagrams and explore the impact of surface windspeed on the diurnal cycle in the cold and warm seasons. In all months, the fall in minimum temperature is reduced with increasing windspeed, which reduces the diurnal temperature range. In July and August, there is an increase of afternoon maximum temperature and humidity at low windspeeds, and a corresponding rise in equivalent potential temperature of 4.4K that appears coupled to increased precipitation. However, overcast skies are associated with the major rain events and higher windspeeds. © 2016 Betts and Tawfik."
"56033466400;6603606681;6603566335;","How large-scale subsidence affects stratocumulus transitions",2016,"10.5194/acp-16-691-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957310963&doi=10.5194%2facp-16-691-2016&partnerID=40&md5=0d5bb93dba2f3ec8723dc4b5a65e2211","Some climate modeling results suggest that the Hadley circulation might weaken in a future climate, causing a subsequent reduction in the large-scale subsidence velocity in the subtropics. In this study we analyze the cloud liquid water path (LWP) budget from large-eddy simulation (LES) results of three idealized stratocumulus transition cases, each with a different subsidence rate. As shown in previous studies a reduced subsidence is found to lead to a deeper stratocumulus-topped boundary layer, an enhanced cloud-top entrainment rate and a delay in the transition of stratocumulus clouds into shallow cumulus clouds during its equatorwards advection by the prevailing trade winds. The effect of a reduction of the subsidence rate can be summarized as follows. The initial deepening of the stratocumulus layer is partly counteracted by an enhanced absorption of solar radiation. After some hours the deepening of the boundary layer is accelerated by an enhancement of the entrainment rate. Because this is accompanied by a change in the cloud-base turbulent fluxes of moisture and heat, the net change in the LWP due to changes in the turbulent flux profiles is negligibly small. © Author(s) 2016."
"55999273500;56463831800;57141453800;55973913400;6701834052;56442378900;","In situ characterization of mixed phase clouds using the Small Ice Detector and the Particle Phase Discriminator",2016,"10.5194/amt-9-159-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956522052&doi=10.5194%2famt-9-159-2016&partnerID=40&md5=5e0f13ea73b5f43685d5a6a49dd3102a","Mixed phase clouds (MPCs) represent a great source of uncertainty for both climate predictions and weather forecasts. In particular, there is still a lack of understanding on how ice forms in these clouds. In this work we present a technique to analyze in situ measurements of MPCs performed with the latest instruments from the Small Ice Detector family. These instruments record high-resolution scattering patterns of individual small cloud particles. For the analysis of the scattering patterns we developed an algorithm that can discriminate the phase of the cloud particles. In the case of a droplet, a Mie solution is fitted to the recorded pattern and the size of the corresponding particle is obtained, which allows for a size calibration of the instrument. In the case of an ice particle, its shape is deduced from the scattering pattern. We apply our data analysis method to measurements from three distinct MPC types. The results from laboratory measurements demonstrate that our technique can discriminate between droplets and ice particles in the same optical size range. This ability was verified by measurements at a mountain top station where we found an alternation of liquid-and ice-dominated cloud regions. The analysis of results from aircraft-based measurements illustrates the ice detection threshold of the technique. © 2016 Author(s)."
"56400726900;7004154626;54901507000;6701874937;35253736000;7801642681;57190218552;6603926727;","Investigation of aerosol indirect effects on monsoon clouds using ground-based measurements over a high-altitude site in Western Ghats",2016,"10.5194/acp-2015-1057","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042813475&doi=10.5194%2facp-2015-1057&partnerID=40&md5=95147a9a374af1a8966d7582c3fb4141","The effect of aerosols on cloud droplet number concentration and droplet effective radius are investigated from ground-based measurements over a high-altitude site where in clouds pass over the surface. First aerosol indirect effect AIE estimates were made using i) relative changes in cloud droplet number concentration (AIEn) and ii) relative changes in droplet effective radius (AIEs) with relative changes in aerosol for different LWC values. AIE estimates from two different methods reveal that there is systematic overestimation in AIEn as compared to that of AIEs. Aerosol indirect effects (AIEn and AIEs) and Dispersion effect (DE) at different liquid water content (LWC) regimes ranging from 0.05 to 0.50 gm-3 were estimated. The analysis demonstrates that there is overestimation of AIEn as compared to AIEs which is mainly due to DE. Aerosol effects on spectral dispersion in droplet size distribution plays an important role in altering Twomey's cooling effect and thereby changes in climate. This study shows that the higher DE in the medium LWC regime which offsets the AIE by 30%. © Author(s) 2016."
"8586682800;7005968859;7005451928;","Prediction of cloud condensation nuclei activity for organic compounds using functional group contribution methods",2016,"10.5194/gmd-9-111-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956640586&doi=10.5194%2fgmd-9-111-2016&partnerID=40&md5=1e8765eccdc0a7eb6d02243159cea0fc","A wealth of recent laboratory and field experiments demonstrate that organic aerosol composition evolves with time in the atmosphere, leading to changes in the influence of the organic fraction to cloud condensation nuclei (CCN) spectra. There is a need for tools that can realistically represent the evolution of CCN activity to better predict indirect effects of organic aerosol on clouds and climate. This work describes a model to predict the CCN activity of organic compounds from functional group composition. Following previous methods in the literature, we test the ability of semi-empirical group contribution methods in Köhler theory to predict the effective hygroscopicity parameter, kappa. However, in our approach we also account for liquid-liquid phase boundaries to simulate phase-limited activation behavior. Model evaluation against a selected database of published laboratory measurements demonstrates that kappa can be predicted within a factor of 2. Simulation of homologous series is used to identify the relative effectiveness of different functional groups in increasing the CCN activity of weakly functionalized organic compounds. Hydroxyl, carboxyl, aldehyde, hydroperoxide, carbonyl, and ether moieties promote CCN activity while methylene and nitrate moieties inhibit CCN activity. The model can be incorporated into scale-bridging test beds such as the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) to evaluate the evolution of kappa for a complex mix of organic compounds and to develop suitable parameterizations of CCN evolution for larger-scale models. © 2016 Author(s)."
"55966909500;7003740015;7006401274;","Size resolved morphological properties of the high Arctic summer aerosol during ASCOS-2008",2016,"10.5194/acp-2015-966","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042814643&doi=10.5194%2facp-2015-966&partnerID=40&md5=f7446ffcff7e6ee55125bc34b9762fdb","The representation of aerosol properties and processes in climate models is fraught with large uncertainties. Especially at high northern latitudes a strong under-prediction of aerosol concentrations and nucleation events is observed and can only be constrained by in situ observations based on the analysis of individual aerosol particles. To further reduce the uncertainties surrounding aerosol properties and their potential role as cloud condensation nuclei this study provides observational data resolved over size on morphological and chemical properties of aerosol particles collected in the summer high Arctic, north of 80° N. Aerosol particles were imaged with scanning and transmission electron microscopy and further evaluated with digital image analysis. In total 3903 particles were imaged and categorized according to morphological similarities into three gross morphological groups, single particles, gel particles and halo particles. Single particles were observed between 15 nm and 800 nm in diameter and represent the dominating type of particles (82%). The majority of particles appeared to be marine gels with a broad Aitken mode peaking at 70 nm accompanied by a minor fraction of ammonium (bi)sulfate with a maximum in number concentration at 170 nm. Gel particles (11% of all particles) were observed between 45 nm and 800 nm with a maximum in number concentration at 154 nm. Imaging with transmission electron microscopy allowed further morphological discrimination of gel particles in ""aggregate"" particles, ""aggregate with film"" particles and ""mucus-like"" particles. © Author(s) 2016."
"6602182223;55173596300;55329113100;6505805689;35329672300;57205638870;57208121852;","Will a perfect model agree with perfect observations? the impact of spatial sampling",2016,"10.5194/acp-2015-973","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042815827&doi=10.5194%2facp-2015-973&partnerID=40&md5=a0d550a0ea103775cee06b21d6d024fd","The spatial resolution of global climate models with interactive aerosol and the observations used to evaluate them is very different. Current models use grid-spacings of ∼ 200 km, while satellite observations of aerosol use so-called pixels of ∼ 10 km. Ground site or air-borne observations concern even smaller spatial scales. We study the errors incurred due to different resolutions by aggregating high-resolution simulations (10 km grid-spacing) over either the large areas of global model grid-boxes (""perfect"" model data) or small areas corresponding to the pixels of satellite measurements or the field-of-view of ground-sites (""perfect"" observations). Our analysis suggests that instantaneous RMS differences between these perfect observations and perfect global models can easily amount to 30-160%, for a range of observables like AOT (Aerosol Optical Thickness), extinction, black carbon mass concentrations, PM2.5, number densities and CCN (Cloud Condensation Nuclei). These differences, due entirely to different spatial sampling of models and observations, are often larger than measurement errors in real observations. Temporal averaging over a month of data reduces these differences more strongly for some observables (e.g. a three-fold reduction i.c. AOT), than for others (e.g. a two-fold reduction for surface black carbon concentrations), but significant RMS differences remain (10-75%). Note that this study ignores the issue of temporal sampling of real observations, which is likely to affect our present monthly error estimates. We examine several other strategies (e.g. spatial aggregation of observations, interpolation of model data) for reducing these differences and show their effectiveness. Finally, we examine consequences for the use of flight campaign data in global model evaluation and show that significant biases may be introduced depending on the flight strategy used. © Author(s) 2016."
"8877858700;6701754792;12800966700;57202425542;","Controls on phase composition and ice water content in a convection permitting model simulation of a tropical mesoscale convective system",2016,"10.5194/acp-2015-970","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042815721&doi=10.5194%2facp-2015-970&partnerID=40&md5=83a8731340cda6f2183ed4d6c73d4acf","Simulations of tropical convection from an operational numerical weather prediction model are evaluated with the focus on the model's ability to simulate the observed high ice water contents associated with the outflow of deep convection and to investigate the modelled processes that control the phase composition of tropical convective clouds. The intensification and decay of convective strength across the mesoscale convective system lifecycle is simulated well, however, the areas with reflectivities > 30 dBZ are overestimated due to too much rain above the freezing level, stronger updrafts and larger particle sizes in the model. The inclusion of a heterogeneous rain freezing parameterisation and the use of different ice size distributions show better agreement with the observed reflectivity distributions, however, this simulation still produces a broader profile with many high reflectivity outliers demonstrating the greater occurrence of convective cells in the simulations. It is shown that the growth of ice is less dependent on vertical velocity than is liquid water, with the control on liquid water content being the updraft strength due to stronger updrafts having minimal entrainment and higher supersaturations. Larger liquid water contents are produced when cloud droplet number concentrations are increased or when a parameterisation of heterogeneous freezing of rain is included. These changes reduce the efficiency of the warm rain processes in the model generating greater supercooled liquid water contents. The control on ice water content in the model is the ice sizes and available liquid water, with the larger ice particles growing more efficiently via accretion and riming. Limiting or excluding graupel produces larger ice water contents for warmer temperatures due to the greater ice mass contained in slow falling snow particles. This results in longer in-cloud residence times and more efficient removal of liquid water. It is demon strated that entrainment in the mixed-phase regions of convective updrafts is most sensitive to the turbulence formulation in the model. Greater mixing of environmental air into cloudy updrafts in the region of -30 to 0 degrees Celsius produces more detrainment at these temperatures and the generation of a larger stratiform area. Above these levels in the purely ice region of the updrafts, the entrainment and buoyancy of air parcels is controlled by the ice particle sizes, demonstrating the importance of the microphysical processes on the convective dynamics. © Author(s) 2016."
"10739072200;6603478665;42662973900;57200999914;57204496157;34568413600;","Continental anthropogenic primary particle number emissions",2016,"10.5194/acp-2015-1023","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85042812264&doi=10.5194%2facp-2015-1023&partnerID=40&md5=7e9c5902191c7f39852f7af2bee3912d","Atmospheric aerosol particle number concentrations impact our climate and health in ways different from those of aerosol mass concentrations. However, the global, current and future, anthropogenic particle number emissions and their size distributions are so far poorly known. In this article, we present the implementation of particle number emission factors and the related size distributions in the GAINS model. This implementation allows for global estimates of particle number emissions under different future scenarios, consistent with emissions of other pollutants and greenhouse gases. In addition to determining the general particulate number emissions, we also describe a method to estimate the number size distributions of the emitted black carbon. The first results show that the sources dominating the particle number emissions are different to those dominating the mass emissions. The major global number source is road traffic, followed by residential combustion of biofuels and coal (especially in China, India and Africa), coke production (Russia and China), and industrial combustion and processes. The size distributions of emitted particles differ across the world, depending on the main sources: in regions dominated by traffic and industry, the number size distribution of emissions peaks in diameters range from 20 to 50 nm, whereas in regions with intensive biofuel combustion and/or agricultural waste burning, the emissions of particles with diameters around 100 nm are dominant. In the baseline (current legislation) scenario, the particle number emissions in Europe, Northern and Southern Americas, Australia, and China decrease until 2030, whereas especially for India, a strong increase is estimated. The results of this study provide input for modelling of the future changes in aerosol-cloud interactions as well as particle number related adverse health effects, e.g., in response to tightening emission regulations. However, there are significant uncertainties in these current emission estimates and the key actions for decreasing the uncertainties are pointed out. © Author(s) 2016."
"56763174500;55745955800;7401936984;","An ensemble constrained variational analysis of atmospheric forcing data and its application to evaluate clouds in CAM5",2016,"10.1002/2015JD024167","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958729688&doi=10.1002%2f2015JD024167&partnerID=40&md5=d0f8d44b0f516e2a8ee35e8fa6c56143","Large-scale atmospheric forcing data can greatly impact the simulations of atmospheric process models (e.g., large eddy simulations, cloud-resolving models, and single column models (SCMs)) that are used to develop physical parameterizations in global climate models. This study introduces an ensemble variationally constrained objective analysis of atmospheric large-scale forcing data and its application to evaluate the cloud biases in the Community Atmospheric Model (CAM5). Sensitivities of the variational objective analysis to background data, error covariance matrix, and constraint variables are presented to quantify the uncertainties in the large-scale forcing data and state variables. Application of the ensemble forcing in the CAM5 SCM during March 2000 intensive operational period at the Southern Great Plains (SGP) of the Atmospheric Radiation Measurement Program shows that the systematic biases in the model simulations (i.e., excessive high clouds and insufficient low clouds) cannot be explained by the uncertainty of large-scale forcing data, which points to the deficiencies of physical parameterizations. These biases are found to also exist in the global simulation of CAM5 when it is compared with satellite data over the surrounding SGP site for annual and seasonal means. © 2015. The Authors."
"7102805852;7407104838;12787547600;8982748700;6602826286;13402835300;55427995800;35096299800;8397494800;9249627300;7202899330;","The impact of equilibrating hemispheric albedos on tropical performance in the HadGEM2-ES coupled climate model",2016,"10.1002/2015GL066903","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957727701&doi=10.1002%2f2015GL066903&partnerID=40&md5=1ae6c96d710ca13597b4a588578aaec5","The Earth's hemispheric reflectances are equivalent to within ± 0.2 Wm-2, even though the Northern Hemisphere contains a greater proportion of higher reflectance land areas, because of greater cloud cover in the Southern Hemisphere. This equivalence is unlikely to be by chance, but the reasons are open to debate. Here we show that equilibrating hemispheric albedos in the Hadley Centre Global Environment Model version 2-Earth System coupled climate model significantly improves what have been considered longstanding and apparently intractable model biases. Monsoon precipitation biases over all continental land areas, the penetration of monsoon rainfall across the Sahel, the West African monsoon ""jump"", and indicators of hurricane frequency are all significantly improved. Mechanistically, equilibrating hemispheric albedos improves the atmospheric cross-equatorial energy transport and increases the supply of tropical atmospheric moisture to the Hadley cell. We conclude that an accurate representation of the cross-equatorial energy transport appears to be critical if tropical performance is to be improved. © 2015. The Authors."
"7102266120;57193213111;26665326700;7101707186;57126848900;7006643234;7006303509;6603133611;7003729315;13403957300;7005891596;7004166136;6603569074;57200679067;57000710600;8608733900;55479853300;6603431534;56084472800;8219523500;12803904100;55740664200;7003620878;55751743740;6507506955;35746906700;7401844779;6602137800;6603293519;57202922977;7102654014;7006027075;7003359002;6701562043;35276210200;7006770898;56164814800;57206166579;6506424404;7005520001;","The two-column aerosol project: Phase I—overview and impact of elevated aerosol layers on aerosol optical depth",2016,"10.1002/2015JD023848","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958729691&doi=10.1002%2f2015JD023848&partnerID=40&md5=799a06fda6e1867f2a55c1cc526e38ee","The Two-Column Aerosol Project (TCAP), conducted from June 2012 through June 2013, was a unique study designed to provide a comprehensive data set that can be used to investigate a number of important climate science questions, including those related to aerosol mixing state and aerosol radiative forcing. The study was designed to sample the atmosphere between and within two atmospheric columns; one fixed near the coast of North America (over Cape Cod, MA) and a second moveable column over the Atlantic Ocean several hundred kilometers from the coast. The U.S. Department of Energy’s (DOE) Atmospheric Radiation Measurement (ARM)Mobile Facility (AMF) was deployed at the base of the Cape Cod column, and the ARMAerial Facility was utilized for the summer and winter intensive observation periods. One important finding from TCAP is that four of six nearly cloud-free flight days had aerosol layers aloft in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA high-spectral resolution lidar (HSRL-2). These layers contributed up to 60% of the total observed aerosol optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the aerosol in the layers was found to have increased amounts of biomass burning material and nitrate compared to aerosol found near the surface. In addition, while there was a great deal of spatial and day-to-day variability in the aerosol chemical composition and optical properties, no systematic differences between the two columns were observed. © 2015. American Geophysical Union. All Rights Reserved."
"55393008200;56423305400;54965273400;55364216300;46460947700;35098387800;","Above-ground biomass and carbon estimates of Shorea robusta and Tectona grandis forests using QuadPOL ALOS PALSAR data",2016,"10.1016/j.asr.2015.11.010","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84954053467&doi=10.1016%2fj.asr.2015.11.010&partnerID=40&md5=3ebfe9ffbdc17a5c4f9912670c79bd6e","Mechanisms to mitigate climate change in tropical countries such as India require information on forest structural components i.e., biomass and carbon for conservation steps to be implemented successfully. The present study focuses on investigating the potential use of a one time, QuadPOL ALOS PALSAR L-band 25 m data to estimate above-ground biomass (AGB) using a water cloud model (WCM) in a wildlife sanctuary in India. A significant correlation was obtained between the SAR-derived backscatter coefficient (σ°) and the field measured AGB, with the maximum coefficient of determination for cross-polarized (HV) σ° for Shorea robusta, and the weakest correlation was observed with co-polarized (HH) σ° for Tectona grandis forests. The biomass of S. robusta and that of T. grandis were estimated on the basis of field-measured data at 444.7 ± 170.4 Mg/ha and 451 ± 179.4 Mg/ha respectively. The mean biomass values estimated using the WCM varied between 562 and 660 Mg/ha for S. robusta; between 590 and 710 Mg/ha for T. grandis using various polarized data. Our results highlighted the efficacy of one time, fully polarized PALSAR data for biomass and carbon estimate in a dense forest. © 2015 COSPAR. Published by Elsevier Ltd. All rights reserved."
"57097508000;35264934000;7101846027;7004885872;","Observational estimates of detrainment and entrainment in non-precipitating shallow cumulus",2016,"10.5194/acp-16-21-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957310019&doi=10.5194%2facp-16-21-2016&partnerID=40&md5=501a86e892a342f0faf9ab17183ee744","Vertical transport associated with cumulus clouds is important to the redistribution of gases, particles, and energy, with subsequent consequences for many aspects of the climate system. Previous studies have suggested that detrainment from clouds can be comparable to the updraft mass flux, and thus represents an important contribution to vertical transport. In this study, we describe a new method to deduce the amounts of gross detrainment and entrainment experienced by non-precipitating cumulus clouds using aircraft observations. The method utilizes equations for three conserved variables: cloud mass, total water, and moist static energy. Optimizing these three equations leads to estimates of the mass fractions of adiabatic mixed-layer air, entrained air and detrained air that the sampled cloud has experienced. The method is applied to six flights of the CIRPAS Twin Otter during the Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) which took place in the Houston, Texas region during the summer of 2006 during which 176 small, non-precipitating cumuli were sampled. Using our novel method, we find that, on average, these clouds were comprised of 30 to 70g% mixed-layer air, with entrained air comprising most of the remainder. The mass fraction of detrained air was usually very small, less than 2g%, although values larger than 10g% were found in 15g% of clouds. Entrained and detrained air mass fractions both increased with altitude, consistent with some previous observational studies. The largest detrainment events were almost all associated with air that was at their level of neutral buoyancy, which has been hypothesized in previous modeling studies. This new method could be readily used with data from other previous aircraft campaigns to expand our understanding of detrainment for a variety of cloud systems. © Author(s) 2016."
"56188363000;57203378050;55470017900;7404548584;","Investigating the frequency and interannual variability in global above-cloud aerosol characteristics with CALIOP and OMI",2016,"10.5194/acp-16-47-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957309460&doi=10.5194%2facp-16-47-2016&partnerID=40&md5=0dd028bea68c5473a9e5158fe0c44f4c","Seven and a half years (June 2006 to November 2013) of Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aerosol and cloud layer products are compared with collocated Ozone Monitoring Instrument (OMI) aerosol index (AI) data and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) cloud products in order to investigate variability in estimates of biannual and monthly above-cloud aerosol (ACA) events globally. The active- (CALIOP) and passive-based (OMI-MODIS) techniques have their advantages and caveats for ACA detection, and thus both are used to derive a thorough and robust comparison of daytime cloudy-sky ACA distribution and climatology. For the first time, baseline above-cloud aerosol optical depth (ACAOD) and AI thresholds are derived and examined (AIg Combining double low line g1.0, ACAODg Combining double low line g0.015) for each sensor. Both OMI-MODIS and CALIOP-based daytime spatial distributions of ACA events show similar patterns during both study periods (December-May) and (June-November). Divergence exists in some regions, however, such as Southeast Asia during June through November, where daytime cloudy-sky ACA frequencies of up to 10g% are found from CALIOP yet are non-existent from the OMI-based method. Conversely, annual cloudy-sky ACA frequencies of 20&ndash;30g% are reported over northern Africa from the OMI-based method yet are largely undetected by the CALIOP-based method. Using a collocated OMI-MODIS-CALIOP data set, our study suggests that the cloudy-sky ACA frequency differences between the OMI-MODIS- and CALIOP-based methods are mostly due to differences in cloud detection capability between MODIS and CALIOP as well as QA flags used. An increasing interannual variability of g1/4 g0.3&ndash;0.4g% per year (since 2009) in global monthly cloudy-sky ACA daytime frequency of occurrence is found using the OMI-MODIS-based method. Yet, CALIOP-based global daytime ACA frequencies exhibit a near-zero interannual variability. Further analysis suggests that the OMI-derived interannual variability in cloudy-sky ACA frequency may be affected by OMI row anomalies in later years. A few regions are found to have increasing slopes in interannual variability in cloudy-sky ACA frequency, including the Middle East and India. Regions with slightly negative slopes of the interannual variability in cloudy-sky ACA frequencies are found over South America and China, while remaining regions in the study show nearly zero change in ACA frequencies over time. The interannual variability in ACA frequency is not, however, statistically significant on both global and regional scales, given the relatively limited sample sizes. A longer data record of ACA events is needed in order to establish significant trends of ACA frequency regionally and globally.</p>. © Author(s) 2016."
"55220443400;","Unrealistic treatment of detrained water substance in FGOALS-s2 and its influence on the model’s climate sensitivity",2016,"10.1080/16742834.2015.1124601","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85075766410&doi=10.1080%2f16742834.2015.1124601&partnerID=40&md5=cb38b56ec0d051fa1a98f31c53ffa324","Based on a series of aqua-planet and air–sea coupled experiments, the influence of unrealistic treatment of water substance in the Flexible Global Ocean–Atmosphere–Land System Model, spectral version 2 (FGOALS-s2), on the model’s climate sensitivity is investigated in this paper. Because the model does not adopt an explicit microphysics scheme, the detrained water substance from the convection scheme is converted back to the humidity. This procedure could lead to an additional increase of water vapor in the atmosphere, which could strengthen the model’s climate sensitivity. Further sensitivity experiments confirm this deduction. After removing the water vapor converted from the detrained water substance, the water vapor reduced significantly in the upper troposphere and the high clouds also reduced. Quantitative calculations show that the water vapor reduced almost 10% of the total water vapor, and 50% at 150 hPa, when the detrained water substance was removed, contributing to the 30% atmospheric surface temperature increase. This study calls for an explicit microphysics scheme to be introduced into the model in order to handle the detrained water vapor and thus improve the model’s simulation skill. © 2016, © 2016 The Author(s). Published by Taylor & Francis."
"55613105600;6701915334;56298802300;6701832491;7404297096;","New insight of Arctic cloud parameterization from regional climate model simulations, satellite-based, and drifting station data",2016,"10.1002/2015GL067530","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978870264&doi=10.1002%2f2015GL067530&partnerID=40&md5=7484cea0cc31823f783b6ec043a25535","Cloud observations from the CloudSat and CALIPSO satellites helped to explain the reduced total cloud cover (Ctot) in the atmospheric regional climate model HIRHAM5 with modified cloud physics. Arctic climate conditions are found to be better reproduced with (1) a more efficient Bergeron-Findeisen process and (2) a more generalized subgrid-scale variability of total water content. As a result, the annual cycle of Ctot is improved over sea ice, associated with an almost 14% smaller area average than in the control simulation. The modified cloud scheme reduces the Ctot bias with respect to the satellite observations. Except for autumn, the cloud reduction over sea ice improves low-level temperature profiles compared to drifting station data. The HIRHAM5 sensitivity study highlights the need for improving accuracy of low-level (&lt;700 m) cloud observations, as these clouds exert a strong impact on the near-surface climate. ©2016. American Geophysical Union. All Rights Reserved."
"55796506900;55355176000;","Advances in studies of cloud overlap and its radiative transfer in climate models",2016,"10.1007/s13351-016-5164-5","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007241901&doi=10.1007%2fs13351-016-5164-5&partnerID=40&md5=4c1115c7a7458ff6c6035d1a3b0e573a","The latest advances in studies on the treatment of cloud overlap and its radiative transfer in global climate models are summarized. Developments with respect to this internationally challenging problem are described from aspects such as the design of cloud overlap assumptions, the realization of cloud overlap assumptions within climate models, and the data and methods used to obtain consistent observations of cloud overlap structure and radiative transfer in overlapping clouds. To date, there has been an appreciable level of achievement in studies on cloud overlap in climate models, demonstrated by the development of scientific assumptions (e.g., e-folding overlap) to describe cloud overlap, the invention and broad application of the fast radiative transfer method for overlapped clouds (Monte Carlo Independent Column Approximation), and the emergence of continuous 3D cloud satellite observation (e.g., CloudSat/CALIPSO) and cloud-resolving models, which provide numerous data valuable for the exact description of cloud overlap structure in climate models. However, present treatments of cloud overlap and its radiative transfer process are far from complete, and there remain many unsettled problems that need to be explored in the future. © The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg 2016."
"25031430500;56699083600;8866821900;57212416832;","Climate feedback variance and the interaction of aerosol forcing and feedbacks",2016,"10.1175/JCLI-D-16-0151.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987958800&doi=10.1175%2fJCLI-D-16-0151.1&partnerID=40&md5=57781a3a466a4184c577c4fe45f0e4ba","Aerosols can influence cloud radiative effects and, thus, may alter interpretation of how Earth's radiative budget responds to climate forcing. Three different ensemble experiments from the same climate model with different greenhouse gas and aerosol scenarios are used to analyze the role of aerosols in climate feedbacks and their spread across initial condition ensembles of transient climate simulations. The standard deviation of global feedback parameters across ensemble members is low, typically 0.02 W m-2 K-1. Feedbacks from high (8.5 W m-2) and moderate (4.5 W m-2) year 2100 forcing cases are nearly identical. An aerosol kernel is introduced to remove effects of aerosol cloud interactions that alias into cloud feedbacks. Adjusted cloud feedbacks indicate an ""aerosol feedback"" resulting from changes to climate that increase sea-salt emissions, mostly in the Southern Ocean. Ensemble simulations also indicate higher tropical cloud feedbacks with higher aerosol loading. These effects contribute to a difference in cloud feedbacks of nearly 50% between ensembles of the same model. These two effects are also seen in aquaplanet simulations with varying fixed drop number. Thus aerosols can be a significant modifier of cloud feedbacks, and different representations of aerosols and their interactions with clouds may contribute to multimodel spread in climate feedbacks and climate sensitivity in multimodel archives. © 2016 American Meteorological Society."
"32867786300;54895907100;","Subgrid-scale cloud-radiation feedback for the Betts-Miller-Janjić convection scheme",2016,"10.1002/qj.2702","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957597302&doi=10.1002%2fqj.2702&partnerID=40&md5=21d63dc0528671429ff966a6e06b6472","Cloud-radiation feedbacks play a crucial role in the climate system and continue to be a major source of uncertainty in global climate model projections. Despite its importance for regional and local circulations, these feedback processes are not included in subgrid-scale convective parametrizations used in regional weather and climate models, in particular in adjustment schemes that, as opposed to mass-flux schemes, do not deal with convective condensates. Here we present a cloud scheme developed for the Betts-Miller-Janjić (BMJ) cumulus scheme used in the Weather Research and Forecasting (WRF) model that is fully general and can easily be applied to any other convective scheme. We parametrize the convective cloud fraction as a function of the BMJ time-step precipitation rate with the vertical cloud profile given by a 'top-heavy' Poisson distribution, similar to observed profiles. The cloud condensates are defined based on the assumption that the mass of convective cloud per unit mass of water vapour in cloudy air is constant in the column. In this scheme there are two tunable parameters:δ, that determines the vertical structure of the convective cloud, and γ, that controls the amount of cloud mass. The performance of the scheme is evaluated in a 1-year run and WRF is found to give a much better representation of the observed cloudiness with smaller biases in the surface radiation fields with respect to observations and reanalysis. © 2016 Royal Meteorological Society."
"12801992200;57198208348;57219951382;","Factors controlling cloud albedo in marine subtropical stratocumulus regions in climate models and satellite observations",2016,"10.1175/JCLI-D-15-0095.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982682901&doi=10.1175%2fJCLI-D-15-0095.1&partnerID=40&md5=0f3088b861f303dce936c78911e157a7","This study focuses on the radiative properties of five subtropical marine stratocumulus cloud regions, on monthly mean scale. Through examination of the relation between total albedo and cloud fraction, and its variability and relation to other parameters, some of the factors controlling the reflectivity, or albedo, of theclouds in these regions are investigated. It is found that the main part of the variability in albedo at a given cloud fraction can be related to temporal rather than spatial variability, indicating spatial homogeneity in cloud radiative properties in the studied regions. This is seen most clearly in satellite observations but also appears in an ensemble of climate models. Further comparison between satellite data and output from climate models shows that there is good agreement with respect to the role of liquid water path, the parameter that can be assumed to be the primary source of variability in cloud reflectivity for a given cloud fraction. On the other hand, the influence of aerosol loading on cloud albedo differs between models and observations. The cloudalbedo effect, or cloud brightening caused by aerosol through its coupling to cloud droplet number concentration and droplet size, is found not to dominate in the satellite observations on monthly mean scale, as it appears to do on this scale in the climate models. The disagreement between models and observations is particularly strong in regions with frequent occurrence of absorbing aerosols above clouds, where satellite data, in contrast to the climate models, indicate a scene darkening with increasing aerosol loading. © 2016 American Meteorological Society."
"54893098900;7401836526;","Constraints on climate sensitivity from space-based measurements of low-cloud reflection",2016,"10.1175/JCLI-D-15-0897.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983522067&doi=10.1175%2fJCLI-D-15-0897.1&partnerID=40&md5=b742df9f9b0de211dd2718f79c1c5a42","Physical uncertainties in global-warming projections are dominated by uncertainties about how the fraction of incoming shortwave radiation that clouds reflect will change as greenhouse gas concentrations rise. Differences in the shortwave reflection by low clouds over tropical oceans alone account for more than half of the variance of the equilibrium climate sensitivity (ECS) among climate models, which ranges from 2.1 to 4.7 K. Space-based measurements now provide an opportunity to assess how well models reproduce temporal variations of this shortwave reflection on seasonal to interannual time scales. Here such space-based measurements are used to show that shortwave reflection by low clouds over tropical oceans decreases robustly when the underlying surface warms, for example, by -(0.96 ± 0.22)%K-1 (90% confidence level) for deseasonalized variations. Additionally, the temporal covariance of low-cloud reflection with temperature in historical simulations with current climate models correlates strongly (r = -0.67) with the models' ECS. Therefore, measurements of temporal low-cloud variations can be used to constrain ECS estimates based on climate models. An information-theoretic weighting of climate models by how well they reproduce the measured deseasonalized covariance of shortwave cloud reflection with temperature yields a most likely ECS estimate around 4.0 K; an ECS below 2.3 K becomes very unlikely (90% confidence). © 2016 American Meteorological Society."
"26659013400;7201443624;25624545600;45661986200;","A multisatellite climatology of clouds, radiation, and precipitation in southern West Africa and comparison to climate models",2016,"10.1002/2016JD025246","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988862009&doi=10.1002%2f2016JD025246&partnerID=40&md5=128e0b38ceb0bb27f8eb281f8f27aedd","Southern West Africa (SWA) has a large population that relies on highly variable monsoon rainfall, yet climate models show little consensus over projected precipitation in this region. Understanding of the current and future climate of SWA is further complicated by rapidly increasing anthropogenic emissions and a lack of surface observations. Using multiple satellite observations, the ERA-Interim reanalysis, and four climate models, we document the climatology of cloud, precipitation, and radiation over SWA in June–July, highlight discrepancies among satellite products, and identify shortcomings in climate models and ERA-Interim. Large differences exist between monthly mean cloud cover estimates from satellites, which range from 68 to 94%. In contrast, differences among satellite observations in top of atmosphere outgoing radiation and surface precipitation are smaller, with monthly means of about 230 W m-2 of longwave radiation, 145 W m-2 of shortwave radiation, and 5.87 mm d-1 of precipitation. Both ERA-Interim and the climate models show less total cloud cover than observations, mainly due to underestimating low cloud cover. Errors in cloud cover, along with uncertainty in surface albedo, lead to a large spread of outgoing shortwave radiation. Both ERA-Interim and the climate models also show signs of convection developing too early in the diurnal cycle, with associated errors in the diurnal cycles of precipitation and outgoing longwave radiation. Clouds, radiation, and precipitation are linked in an analysis of the regional energy budget, which shows that interannual variability of precipitation and dry static energy divergence are strongly linked. © 2016. American Geophysical Union. All Rights Reserved."
"55977336000;16637291100;","Assessment of arctic cloud cover anomalies in atmospheric reanalysis products using satellite data",2016,"10.1175/JCLI-D-15-0861.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983494453&doi=10.1175%2fJCLI-D-15-0861.1&partnerID=40&md5=1dd10e379887c7fd05fbd2231471651e","Cloud cover is one of the largest uncertainties in model predictions of the future Arctic climate. Previous studies have shown that cloud amounts in global climate models and atmospheric reanalyses vary widely and may have large biases. However, many climate studies are based on anomalies rather than absolute values, for which biases are less important. This study examines the performance of five atmospheric reanalysis products-ERA-Interim, MERRA, MERRA-2, NCEP R1, and NCEP R2-in depicting monthly mean Arctic cloud amount anomalies against Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations from 2000 to 2014 and against Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) observations from 2006 to 2014. All five reanalysis products exhibit biases in the mean cloud amount, especially in winter. The Gerrity skill score (GSS) and correlation analysis are used to quantify their performance in terms of interannual variations. Results show that ERA-Interim, MERRA, MERRA-2, and NCEP R2 perform similarly, with annual mean GSSs of 0.36/0.22, 0.31/0.24, 0.32/0.23, and 0.32/0.23 and annualmean correlation coefficients of 0.50/0.51, 0.43/0.54, 0.44/0.53, and 0.50/0.52 againstMODIS/CALIPSO, indicating that the reanalysis datasets do exhibit some capability for depicting the monthlymean cloud amount anomalies. There are no significant differences in the overall performance of reanalysis products. They all perform best in July, August, and September and worst in November, December, and January. All reanalysis datasets have better performance over land than over ocean. This study identifies the magnitudes of errors in Arctic mean cloud amounts and anomalies and provides a useful tool for evaluating future improvements in the cloud schemes of reanalysis products."
"7801642934;26647492000;","Cloud regimes as phase transitions",2016,"10.1002/2016GL069396","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978204183&doi=10.1002%2f2016GL069396&partnerID=40&md5=40f20c3ce76ace30595d99352f3bac0f","Clouds are repeatedly identified as a leading source of uncertainty in future climate predictions. Of particular importance are stratocumulus clouds, which can appear as either (i) closed cells that reflect solar radiation back to space or (ii) open cells that allow solar radiation to reach the Earth's surface. Here we show that these clouds regimes—open versus closed cells—fit the paradigm of a phase transition. In addition, this paradigm characterizes pockets of open cells as the interface between the open- and closed-cell regimes, and it identifies shallow cumulus clouds as a regime of higher variability. This behavior can be understood using an idealized model for the dynamics of atmospheric water as a stochastic diffusion process. With this new conceptual viewpoint, ideas from statistical mechanics could potentially be used for understanding uncertainties related to clouds in the climate system and climate predictions. ©2016. American Geophysical Union. All Rights Reserved."
"16202694600;8866821900;","Understanding the varied influence of midlatitude jet position on clouds and cloud radiative effects in observations and global climate models",2016,"10.1175/JCLI-D-16-0295.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85001129201&doi=10.1175%2fJCLI-D-16-0295.1&partnerID=40&md5=643798e509e718599a55450a539d5633","This study examines the dynamical mechanisms responsible for changes in midlatitude clouds and cloud radiative effects (CRE) that occur in conjunction with meridional shifts in the jet streams over the North Atlantic, North Pacific, and Southern Oceans. When the midlatitude jet shifts poleward, extratropical cyclones and their associated upward vertical velocity anomalies closely follow. As a result, a poleward jet shift contributes to a poleward shift in high-topped storm-track clouds and their associated longwave CRE. However, when the jet shifts poleward, downward vertical velocity anomalies increase equatorward of the jet, contributing to an enhancement of the boundary layer estimated inversion strength (EIS) and an increase in low cloud amount there. Because shortwave CRE depends on the reflection of solar radiation by clouds in all layers, the shortwave cooling effects of midlatitude clouds increase with both upward vertical velocity anomalies and positive EIS anomalies. Over midlatitude oceans where a poleward jet shift contributes to positive EIS anomalies but downward vertical velocity anomalies, the two effects cancel, and net observed changes in shortwave CRE are small. Global climate models generally capture the observed anomalies associated with midlatitude jet shifts. However, there is large intermodel spread in the shortwave CRE anomalies, with a subset of models showing a large shortwave cloud radiative warming over midlatitude oceans with a poleward jet shift. In these models, midlatitude shortwave CRE is sensitive to vertical velocity perturbations, but the observed sensitivity to EIS perturbations is underestimated. Consequently, these models might incorrectly estimate future midlatitude cloud feedbacks in regions where appreciable changes in both vertical velocity and EIS are projected. © 2016 American Meteorological Society."
"57197840302;14036628000;","Progressive midlatitude afforestation: Impacts on clouds, global energy transport, and precipitation",2016,"10.1175/jcli-d-15-0748.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016333409&doi=10.1175%2fjcli-d-15-0748.1&partnerID=40&md5=b0275e8c2a2e514fee4a7bb1e15945f5","Vegetation influences the atmosphere in complex and nonlinear ways, such that large-scale changes in vegetation cover can drive changes in climate on both local and global scales. Large-scale land surface changes have been shown to introduce excess energy to one hemisphere, causing a shift in atmospheric circulation on a global scale. However, past work has not quantified how the climate response scales with the area of vegetation. Here, the response of climate to linearly increasing the area of forest cover in the northern midlatitudes is systematically evaluated. This study shows that the magnitude of afforestation of the northern midlatitudes determines the local climate response in a nonlinear fashion, and the authors identify a threshold in vegetation-induced cloud feedbacks-a concept not previously addressed by large-scale vegetation manipulation experiments. Small increases in tree cover drive compensating cloud feedbacks, while latent heat fluxes reach a threshold after sufficiently large increases in tree cover, causing the troposphere to warm and dry, subsequently reducing cloud cover. Increased absorption of solar radiation at the surface is driven by both surface albedo changes and cloud feedbacks. This study shows how atmospheric cross-equatorial energy transport changes as the area of afforestation is incrementally increased. The results highlight the importance of considering both local and remote climate effects of large-scale vegetation change and explore the scaling relationship between changes in vegetation cover and resulting climate impacts. © 2016 American Meteorological Society."
"6603631763;7202970886;56111948600;56663009100;12801836100;56703527900;","Using the NASA EOS A-train to probe the performance of the NOAA PATMOS-x cloud fraction CDR",2016,"10.3390/rs8060511","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84974817449&doi=10.3390%2frs8060511&partnerID=40&md5=468e88185b4281c5e00ba5000005e036","An important component of the AVHRR PATMOS-x climate date record (CDR)-or any satellite cloud climatology-is the performance of its cloud detection scheme and the subsequent quality of its cloud fraction CDR. PATMOS-x employs the NOAA Enterprise Cloud Mask for this, which is based on a naïve Bayesian approach. The goal of this paper is to generate analysis of the PATMOS-x cloud fraction CDR to facilitate its use in climate studies. Performance of PATMOS-x cloud detection is compared to that of the well-established MYD35 and CALIPSO products from the EOS A-Train. Results show the AVHRR PATMOS-x CDR compares well against CALIPSO with most regions showing proportional correct values of 0.90 without any spatial filtering and 0.95 when a spatial filter is applied. Values are similar for the NASA MODIS MYD35 mask. A direct comparison of PATMOS-x and MYD35 from 2003 to 2014 also shows agreement over most regions in terms of mean cloud amount, inter-annual variability, and linear trends. Regional and seasonal differences are discussed. The analysis demonstrates that PATMOS-x cloud amount uncertainty could effectively screen regions where PATMOS-x differs from MYD35."
"16637291100;7501855361;55977336000;26532573000;57160391500;","The AVHRR polar Pathfinder climate data records",2016,"10.3390/rs8030167","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962575010&doi=10.3390%2frs8030167&partnerID=40&md5=b57620987966aab6d7cf356cc6936db8","With recent, dramatic changes in Arctic sea ice and the Antarctic ice sheets, the importance of monitoring the climate of the polar regions has never been greater. While many individual global satellite products exist, the AVHRR Polar Pathfinder products provide a comprehensive set of variables that can be used to study trends and interactions within the Arctic and Antarctic climate systems. This paper describes the AVHRR Polar Pathfinder (APP), which is a fundamental climate data record that provides channel reflectances and brightness temperatures, and the AVHRR Polar Pathfinder-Extended (APP-x), which is a thematic climate data record that builds on APP to provide information on surface and cloud properties and radiative fluxes. Both datasets cover the period from 1982 through the present, twice daily, over both polar regions. APP-x has been used in the study of trends in surface properties, cloud cover, and radiative fluxes, interactions between clouds and sea ice, and the role of land surface changes in summer warming. © 2016 by the authors."
"57203030873;25222766500;57190852346;57188924386;56297151300;6603925960;7102645933;","Evaluating and improving cloud phase in the community atmosphere model version 5 using spaceborne lidar observations",2016,"10.1002/2015JD024699","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964284077&doi=10.1002%2f2015JD024699&partnerID=40&md5=bfc3b53455805d30d842cf87306b9374","Spaceborne lidar observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite are used to evaluate cloud amount and cloud phase in the Community Atmosphere Model version 5 (CAM5), the atmospheric component of a widely used state-of-the-art global coupled climate model (Community Earth System Model). By embedding a lidar simulator within CAM5, the idiosyncrasies of spaceborne lidar cloud detection and phase assignment are replicated. As a result, this study makes scale-aware and definition-aware comparisons between model-simulated and observed cloud amount and cloud phase. In the global mean, CAM5 has insufficient liquid cloud and excessive ice cloud when compared to CALIPSO observations. Over the ice-covered Arctic Ocean, CAM5 has insufficient liquid cloud in all seasons. Having important implications for projections of future sea level rise, a liquid cloud deficit contributes to a cold bias of 2–3°C for summer daily maximum near-surface air temperatures at Summit, Greenland. Over themidlatitude stormtracks, CAM5 has excessive ice cloud and insufficient liquid cloud. Storm track cloud phase biases in CAM5 maximize over the Southern Ocean, which also has larger-than-observed seasonal variations in cloud phase. Physical parameter modifications reduce the Southern Ocean cloud phase and shortwave radiation biases in CAM5 and illustrate the power of the CALIPSO observations as an observational constraint. The results also highlight the importance of using a regime-based, as opposed to a geographic-based, model evaluation approach. More generally, the results demonstrate the importance and value of simulator-enabled comparisons of cloud phase in models used for future climate projection. © 2016. American Geophysical Union. All Rights Reserved."
"36701462300;10241250100;55686667100;10243650000;10241462700;7102857642;","Lower-tropospheric mixing as a constraint on cloud feedback in a multiparameter multiphysics ensemble",2016,"10.1175/JCLI-D-16-0042.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983490086&doi=10.1175%2fJCLI-D-16-0042.1&partnerID=40&md5=6280a8dcc3db8d96cab2c1ade2403b6c","Factors and possible constraints to extremely large spread of effective climate sensitivity (ECS) ranging about 2.1-10.4K are examined by using a large-member ensemble of quadrupling CO2 experiments with an atmospheric general circulation model (AGCM). The ensemble, called the multiparameter multiphysics ensemble (MPMPE), consists of both parametric and structural uncertainties in parameterizations of cloud, cumulus convection, and turbulence based on two different versions of AGCM. The sum of the low- and middle-cloud shortwave feedback explains most of the ECS spread among the MPMPE members. For about half of the perturbed physics ensembles (PPEs) in the MPMPE, variation in lower-tropospheric mixing intensity (LTMI) corresponds well with the ECS variation, whereas it does not for the other half. In the latter PPEs, large spread in optically thick middle-cloud feedback over the equatorial ocean substantially affects the ECS, disrupting the LTMI-ECS relationship. Although observed LTMI can constrain uncertainty in the lowcloud feedback, total uncertainty of the ECS among the MPMPE cannot solely be explained by the LTMI, suggesting a limitation of single emergent constraint for the ECS."
"28367935500;7201784177;","Impact of regional atmospheric cloud radiative changes on shifts of the extratropical jet stream in response to global warming",2016,"10.1175/JCLI-D-16-0140.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996618846&doi=10.1175%2fJCLI-D-16-0140.1&partnerID=40&md5=e6a2ee0086467bec9c159fd2bdfd84b8","Climate models robustly project that global warming will lead to a poleward shift of the annual-mean zonal-mean extratropical jet streams. The magnitude of such shifts remains uncertain, however, and recent work has indicated a potentially important role of cloud radiative interactions. The model spread found in realistic simulations with interactive sea surface temperatures (SSTs) is captured in aquaplanet simulations with prescribed SSTs, because of which the latter setup is adapted here to study the impact of regional atmospheric cloud radiative changes on the jet position. Simulations with two CMIP5 models and prescribed regional cloud changes show that the rise of tropical high-level clouds and the upward and poleward movement of midlatitude high-level clouds lead to poleward jet shifts. High-latitude low-level cloud changes shift the jet poleward in one model but not in the other. The impact of clouds on the jet operates via the atmospheric radiative forcing that is created by the cloud changes and is qualitatively reproduced in a dry model, although the latter is too sensitive because of its simplified treatment of diabatic processes. The 10-model CMIP5 aquaplanet ensemble of global warming exhibits correlations between jet shifts, regional temperature changes, and regional cloud changes that are consistent with the prescribed cloud simulations. This provides evidence that the atmospheric radiative forcing from tropical and midlatitude high-level cloud changes contributes to model uncertainty in future jet shifts, in addition to the surface radiative forcing from extratropical cloud changes highlighted by previous studies. © 2016 American Meteorological Society."
"7202970886;6603631763;56663009100;6506058533;12801836100;56111948600;","PATMOS-x cloud climate record trend sensitivity to reanalysis products",2016,"10.3390/rs8050424","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971424574&doi=10.3390%2frs8050424&partnerID=40&md5=1ba0563ef0e778276548cfbecd52b4a6","Continuous satellite-derived cloud records now extend over three decades, and are increasingly used for climate applications. Certain applications, such as trend detection, require a clear understanding of uncertainty as it relates to establishing statistical significance. The use of reanalysis products as sources of ancillary data could be construed as one such source of uncertainty, as there has been discussion regarding the suitability of reanalysis products for trend detection. Here we use three reanalysis products: Climate Forecast System Reanalysis (CFSR), Modern Era Retrospective Analysis for Research and Applications (MERRA) and European Center for Medium range Weather Forecasting (ECMWF) ERA-Interim (ERA-I) as sources of ancillary data for the Pathfinder Atmospheres Extended/Advanced Very High Resolution Radiometer (PATMOS-x/AVHRR) Satellite Cloud Climate Data Record (CDR), and perform inter-comparisons to determine how sensitive the climatology is to choice of ancillary data source. We find differences among reanalysis fields required for PATMOS-x processing, which translate to small but not insignificant differences in retrievals of cloud fraction, cloud top height and cloud optical depth. The retrieval variability due to choice of reanalysis product is on the order of one third the size of the retrieval uncertainty, making it a potentially significant factor in trend detection. Cloud fraction trends were impacted the most by choice of reanalysis while cloud optical depth trends were impacted the least. Metrics used to determine the skill of the reanalysis products for use as ancillary data found no clear best choice for use in PATMOS-x. We conclude use of reanalysis products as ancillary data in the PATMOS-x/AVHRR Cloud CDR do not preclude its use for trend detection, but for that application uncertainty in reanalysis fields should be better represented in the PATMOS-x retrieval uncertainty. © 2016 by the authors."
"55728994600;42561605900;57188978164;55467448100;","A cloud-enabled remote visualization tool for time-varying climate data analytics",2016,"10.1016/j.envsoft.2015.10.033","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964533547&doi=10.1016%2fj.envsoft.2015.10.033&partnerID=40&md5=7bbd9d5180adb72d1fa87836b65c1796","The ever-growing time-varying climate datasets pose challenges for efficient analytics using the current desktop-based or generic remote visualization tools. We present a tightly-coupled scalable cloud-enabled remote visualization tool that exploits the computational capabilities of Graphical Processing Units (GPUs). We implement three typical volumetric/3D visualization techniques to illustrate the enhanced performance offered by remote GPU clusters. Our development also enables fast deployment to facilitate the access of remote analytics tools by a wide range of end users. © 2015 Elsevier Ltd."
"7103246957;57192406796;57192405370;57192403574;","Integrating solar energy and climate research into science education",2016,"10.1002/2015EF000315","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006200817&doi=10.1002%2f2015EF000315&partnerID=40&md5=c009c330bbc73b96c8a1b02ab8848f16","This paper analyzes multi-year records of solar flux and climate data from two solar power sites in Vermont. We show the inter-annual differences of temperature, wind, panel solar flux, electrical power production, and cloud cover. Power production has a linear relation to a dimensionless measure of the transmission of sunlight through the cloud field. The difference between panel and air temperatures reaches 24C with high solar flux and low wind speed. High panel temperatures that occur in summer with low wind speeds and clear skies can reduce power production by as much as 13%. The intercomparison of two sites 63 km apart shows that while temperature is highly correlated on daily (R2=0.98) and hourly (R2=0.94) timescales, the correlation of panel solar flux drops markedly from daily (R2=0.86) to hourly (R2=0.63) timescales. Minimum temperatures change little with cloud cover, but the diurnal temperature range shows a nearly linear increase with falling cloud cover to 16C under nearly clear skies, similar to results from the Canadian Prairies. The availability of these new solar and climate datasets allows local student groups, a Rutland High School team here, to explore the coupled relationships between climate, clouds, and renewable power production. As our society makes major changes in our energy infrastructure in response to climate change, it is important that we accelerate the technical education of high school students using real-world data. © 2016 The Authors."
"36856321600;26645289600;57210518852;55575258400;","Quantifying the sources of intermodel spread in equilibrium climate sensitivity",2016,"10.1175/JCLI-D-15-0352.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957824678&doi=10.1175%2fJCLI-D-15-0352.1&partnerID=40&md5=614375d4d9e1241ddbc46eaeee91aced","This study clarifies the causes of intermodel differences in the global-average temperature response to doubled CO2, commonly known as equilibriumclimate sensitivity (ECS). The authors begin by noting several issues with the standard approach for decomposing ECS into a sum of forcing and feedback terms. This leads to a derivation of an alternative method based on linearizing the effect of the net feedback. Consistent with previous studies, the new method identifies shortwave cloud feedback as the dominant source of intermodel spread in ECS. This new approach also reveals that covariances between cloud feedback and forcing, between lapse rate and longwave cloud feedbacks, and between albedo and shortwave cloud feedbacks play an important and previously underappreciated role in determining model differences in ECS. Defining feedbacks based on fixed relative rather than specific humidity (as suggested by Held and Shell) reduces the covariances between processes and leads to more straightforward interpretations of results. © 2016 American Meteorological Society."
"55286185400;6701752471;7005808242;56744278700;57208455668;7006306835;57208462871;8733579800;7103271625;23486734100;50261552200;","Uncertainty in model climate sensitivity traced to representations of cumulus precipitation microphysics",2016,"10.1175/JCLI-D-15-0191.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957828230&doi=10.1175%2fJCLI-D-15-0191.1&partnerID=40&md5=e46c25d15b4ae702dbae62a6c958af41","Uncertainty in equilibrium climate sensitivity impedes accurate climate projections. While the intermodel spread is known to arise primarily from differences in cloud feedback, the exact processes responsible for the spread remain unclear. To help identify some key sources of uncertainty, the authors use a developmental version of the next-generation Geophysical Fluid Dynamics Laboratory global climate model (GCM) to construct a tightly controlled set of GCMs where only the formulation of convective precipitation is changed. The different models provide simulation of present-day climatology of comparable quality compared to the model ensemble from phase 5 of CMIP (CMIP5). The authors demonstrate that model estimates of climate sensitivity can be strongly affected by the manner through which cumulus cloud condensate is converted into precipitation in a model's convection parameterization, processes that are only crudely accounted for in GCMs. In particular, two commonly used methods for converting cumulus condensate into precipitation can lead to drastically different climate sensitivity, as estimated here with an atmosphere-land model by increasing sea surface temperatures uniformly and examining the response in the top-of-atmosphere energy balance. The effect can be quantified through a bulk convective detrainment efficiency, whichmeasures the ability of cumulus convection to generate condensate per unit precipitation. The model differences, dominated by shortwave feedbacks, come from broad regimes ranging from large-scale ascent to subsidence regions. Given current uncertainties in representing convective precipitation microphysics and the current inability to find a clear observational constraint that favors one version of the authors'model over the others, the implications of this ability to engineer climate sensitivity need to be considered when estimating the uncertainty in climate projections. © 2016 American Meteorological Society."
"54897465300;7202145115;","Clouds and the atmospheric circulation response to warming",2016,"10.1175/JCLI-D-15-0394.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957804102&doi=10.1175%2fJCLI-D-15-0394.1&partnerID=40&md5=5f13669e22184d95dd26a0b636e4b1d8","The authors study the effect of clouds on the atmospheric circulation response to CO2 quadrupling in an aquaplanet model with a slab ocean lower boundary. The cloud effect is isolated by locking the clouds to either the control or 4xCO2 state in the shortwave (SW) or longwave (LW) radiation schemes. In the model, cloud radiative changes explain more than half of the total poleward expansion of the Hadley cells, midlatitude jets, and storm tracks under CO2 quadrupling, even though they cause only one-fourth of the total global-mean surface warming. The effect of clouds on circulation results mainly from the SW cloud radiative changes, which strongly enhance the equator-to-pole temperature gradient at all levels in the troposphere, favoring stronger and poleward-shifted midlatitude eddies. By contrast, quadrupling CO2 while holding the clouds fixed causes strong polar amplification and weakened midlatitude baroclinicity at lower levels, yielding only a small poleward expansion of the circulation. The results show that 1) the atmospheric circulation responds sensitively to cloud-driven changes in meridional and vertical temperature distribution and 2) the spatial structure of cloud feedbacks likely plays a dominant role in the circulation response to greenhouse gas forcing. While the magnitude and spatial structure of the cloud feedback are expected to be highly model dependent, an analysis of 4xCO2 simulations of CMIP5 models shows that the SW cloud feedback likely forces a poleward expansion of the tropospheric circulation in most climate models. © 2016 American Meteorological Society."
"56999327800;6603631763;12801836100;","Climatology analysis of aerosol effect on marine water cloud from long-term satellite climate data records",2016,"10.3390/rs8040300","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971602989&doi=10.3390%2frs8040300&partnerID=40&md5=8c7d9f41f0dfbfd8332fa8ccfc6b34bb","Satellite aerosol and cloud climate data records (CDRs) have been used successfully to study the aerosol indirect effect (AIE). Data from the Advanced Very High Resolution Radiometer (AVHRR) now span more than 30 years and allow these studies to be conducted from a climatology perspective. In this paper, AVHRR data are used to study the AIE on water clouds over the global oceans. Correlation analysis between aerosol optical thickness (AOT) and cloud parameters, including cloud droplet effective radius (CDER), cloud optical depth (COD), cloud water path (CWP), and cloud cover fraction (CCF), is performed. For the first time from satellite observations, the long-term trend in AIE over the global oceans is also examined. Three regimes have been identified: (1) AOT < 0.08, where CDER increases with AOT; (2) 0.08 < AOT < 0.3, where CDER generally decreases when AOT increases; and (3) AOT > 0.3, where CDER first increases with AOT and then levels off. AIE is easy to manifest in the CDER reduction in the second regime (named Regime 2), which is identified as the AIE sensitive/effective regime. The AIE manifested in the consistent changes of all four cloud variables (CDER, COD, CWP, and CCF) together is located only in limited areas and with evident seasonal variations. The long-term trend of CDER changes due to the AIE of AOT changes is detected and falls into three scenarios: Evident CDER decreasing (increasing) with significant AOT increasing (decreasing) and evident CDER decreasing with limited AOT increasing but AOT values fall in the AIE sensitive Regime 2. © 2016 by the authors."
"54897465300;7202145115;7201485519;","Mechanisms of the negative shortwave cloud feedback in middle to high latitudes",2016,"10.1175/JCLI-D-15-0327.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957673640&doi=10.1175%2fJCLI-D-15-0327.1&partnerID=40&md5=f4724f3fb3266e86ee3a697ca8bef616","Increases in cloud optical depth and liquid water path (LWP) are robust features of global warming model simulations in high latitudes, yielding a negative shortwave cloud feedback, but the mechanisms are still uncertain. Here the importance of microphysical processes for the negative optical depth feedback is assessed by perturbing temperature in the microphysics schemes of two aquaplanet models, both of which have separate prognostic equations for liquid water and ice. It is found that most of the LWP increase with warming is caused by a suppression of ice microphysical processes in mixed-phase clouds, resulting in reduced conversion efficiencies of liquid water to ice and precipitation. Perturbing the temperature-dependent phase partitioning of convective condensate also yields a small LWP increase. Together, the perturbations in large-scale microphysics and convective condensate partitioning explain more than two-thirds of the LWP response relative to a reference case with increased SSTs, and capture all of the vertical structure of the liquid water response. In support of these findings, a very robust positive relationship between monthly mean LWP and temperature in CMIP5 models and observations is shown to exist in mixed-phase cloud regions only. In models, the historical LWP sensitivity to temperature is a good predictor of the forced global warming response poleward of about 45°, although models appear to overestimate the LWP response to warming compared to observations. The results indicate that in climate models, the suppression of ice-phase microphysical processes that deplete cloud liquid water is a key driver of the LWP increase with warming and of the associated negative shortwave cloud feedback. © 2016 American Meteorological Society."
"7005956183;56270311300;7004540083;6602844274;7102953444;","Comparison of radiative energy flows in observational datasets and climate modeling",2016,"10.1175/JAMC-D-14-0281.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956857093&doi=10.1175%2fJAMC-D-14-0281.1&partnerID=40&md5=1ad362a7baeea04d45a6238c67a0f21b","This study examines radiative flux distributions and local spread of values from three major observational datasets (CERES, ISCCP, and SRB) and compares them with results from climate modeling (CMIP3). Examinations of the spread and differences also differentiate among contributions from cloudy and clear-sky conditions. The spread among observational datasets is in large part caused by noncloud ancillary data. Average differences of at least 10 W m-2 each for clear-sky downward solar, upward solar, and upward infrared fluxes at the surface demonstrate via spatial difference patterns major differences in assumptions for atmospheric aerosol, solar surface albedo and surface temperature, and/or emittance in observational datasets. At the top of the atmosphere (TOA), observational datasets are less influenced by the ancillary data errors than at the surface. Comparisons of spatial radiative flux distributions at the TOA between observations and climate modeling indicate large deficiencies in the strength and distribution of model-simulated cloud radiative effects. Differences are largest for lower-altitude clouds over low-latitude oceans. Global modeling simulates stronger cloud radiative effects (CRE) by +30 W m-2 over trade wind cumulus regions, yet smaller CRE by about -30 W m-2 over (smaller in area) stratocumulus regions. At the surface, climate modeling simulates on average about 15 W m-2 smaller radiative net flux imbalances, as if climate modeling underestimates latent heat release (and precipitation). Relative to observational datasets, simulated surface net fluxes are particularly lower over oceanic trade wind regions (where global modeling tends to overestimate the radiative impact of clouds). Still, with the uncertainty in noncloud ancillary data, observational data do not establish a reliable reference. © 2016 American Meteorological Society."
"25640569400;56321122100;57191224149;","A climatology of clouds in marine cold air outbreaks in both hemispheres",2016,"10.1175/JCLI-D-15-0783.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987971000&doi=10.1175%2fJCLI-D-15-0783.1&partnerID=40&md5=11ae89666225b2227054ecac9071e4e8","A climatology of clouds within marine cold air outbreaks, primarily using long-term satellite observations, is presented. Cloud properties between cold air outbreaks in different regions in both hemispheres are compared. In all regions marine cold air outbreak clouds tend to be low level with high cloud fraction and low-to-moderate optical thickness. Stronger cold air outbreaks have clouds that are optically thicker, but not geometrically thicker, than those in weaker cold air outbreaks. There is some evidence that clouds deepen and break up over the course of a cold air outbreak event. The top-of-the-atmosphere longwave cloud radiative effect in cold air outbreaks is small because the clouds have low tops. However, their surface longwave cloud radiative effect is considerably larger. The rarity of cold air outbreaks in summer limits their shortwave cloud radiative effect. They do not contribute substantially to global shortwave cloud radiative effect and are, therefore, unlikely to be a major source of shortwave cloud radiative effect errors in climate models. © 2016 American Meteorological Society."
"57194833104;57203053317;","Constraining precipitation susceptibility of warm-, ice-, and mixed-phase clouds with microphysical equations",2016,"10.1175/JAS-D-16-0008.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015326597&doi=10.1175%2fJAS-D-16-0008.1&partnerID=40&md5=d4f0a0980238684a6367ab9f1ea799f5","The strength of the effective anthropogenic climate forcing from aerosol-cloud interactions is related to the susceptibility of precipitation to aerosol effects. Precipitation susceptibility d lnP/d lnN has been proposed as a metric to quantify the effect of aerosol-induced changes in cloud droplet number N on warm precipitation rate P. Based on the microphysical rate equations of the Seifert and Beheng two-moment bulk microphysics scheme, susceptibilities of warm-, mixed-, and ice-phase precipitation and cirrus sedimentation to cloud droplet and ice crystal number are estimated. The estimation accounts for microphysical adjustments to the initial perturbation in N. For warm rain, d lnP/d lnN < -2aut/(aut + acc) is found, which depends on the rates of autoconversion (aut) and accretion (acc). Cirrus sedimentation susceptibility corresponds to the exponent of crystal sedimentation velocity with a value of -0.2. For mixed-phase clouds, several microphysical contributions that explain low precipitation susceptibilities are identified: (i) Because of the larger hydrometeor sizes involved, mixed-phase collection processes are less sensitive to changes in hydrometeor size than autoconversion. (ii) Only a subset of precipitation formation processes is sensitive to droplet or crystal number. (iii) Effects on collection processes and diffusional growth compensate. (iv) Adjustments in cloud liquid and ice amount compensate the effect of changes in ice crystal and cloud droplet number. (v) Aerosol perturbations that simultaneously affect ice crystal and droplet number have opposing effects. © 2016 American Meteorological Society."
"8117864800;7401945370;9838847000;56493740900;16643471600;7403577184;9535769800;35454141800;36722732500;","Evaluating arctic cloud radiative effects simulated by NICAM with a-train",2016,"10.1002/2016JD024775","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977139488&doi=10.1002%2f2016JD024775&partnerID=40&md5=47120eba2d37754e22c18a37dc8f081e","Evaluation of cloud radiative effects (CREs) in global atmospheric models is of vital importance to reduce uncertainties in weather forecasting and future climate projection. In this paper, we describe an effective way to evaluate CREs from a 3.5 km mesh global nonhydrostatic model by comparing it against A-train satellite data. The model is the Nonhydrostatic Icosahedral Atmospheric Model (NICAM), and its output is run through a satellite-sensor simulator (Joint Simulator for satellite sensors) to produce the equivalent CloudSat radar, CALIPSO lidar, and Aqua Clouds and the Earth’s Radiant Energy System (CERES) data. These simulated observations are then compared to real observations from the satellites.Wefocus on the Arctic, which is a region experiencing rapid climate change over various surface types. The NICAM simulation significantly overestimates the shortwave CREs at top of atmosphere and surface as large as 24Wm-2 for the month of June. The CREs were decomposed into cloud fractions and footprint CREs of cloud types that are defined based on the CloudSat-CALIPSO cloud top temperature and maximum radar reflectivity. It turned out that the simulation underestimates the cloud fraction and optical thickness of mixed-phase clouds due to predicting too little supercooled liquid and predicting overly large snow particles with too little mass content. This bias was partially offset by predicting too many optically thin high clouds. Offline sensitivity experiments, where cloud microphysical parameters, surface albedo, and single scattering parameters are varied, support the diagnosis. Aerosol radiative effects and nonspherical single scattering of ice particles should be introduced into the NICAM broadband calculation for further improvement. © 2016. American Geophysical Union. All Rights Reserved."
"56143929800;7003842561;45061126700;","Implementation of a new empirical relationship between aerosol and cloud droplet concentrations in a climate model",2016,"10.3354/cr01415","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020451337&doi=10.3354%2fcr01415&partnerID=40&md5=a9c1653b64a90ed7274ab0c26a7cdbca","A new empirical relationship between aerosol and cloud droplet number concentrations (Naer and Nd, respectively) was established based on observed data from different regions around the world to implement in the Hadley Centre Global Environmental Model version 2-Atmosphere-Ocean (HadGEM2-AO). Compared to the original relationship used in HadGEM2-AO, which utilized observed data from only limited regions, this new relationship provides a lower Nd than the original relationship for Naer &lt; 680 cm-3, and the opposite for Naer &gt; 680 cm-3. The complete historical run with the new relationship (newHIST) shows a number of significant differences from the original historical run (HIST). Nd increased in industrialized regions while it generally decreased over the oceanic regions in newHIST compared to HIST. Interestingly, in newHIST a significant change in total cloud amount occurred mainly in the intertropical convergence zone (ITCZ) due to a change in the wind circulation pattern over the North Pacific. Notably, the surface temperature in newHIST was closer to the observational data than that in HIST - especially over the Northern Hemisphere. Despite the small change in Nd in the new relationship, not only the variables directly associated with cloud microphysics but also the variables representing atmospheric circulation patterns changed significantly. This implies that accurate parameterization of Nd is critical for better climate model prediction. © Inter-Research 2016."
"36243762400;7006041988;7202208148;35389411400;13006055400;54783792600;7003663305;19337612500;6701754792;","Understanding rapid changes in phase partitioning between cloud liquid and ice in stratiform mixed-phase clouds: An arctic case study",2016,"10.1175/MWR-D-16-0155.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020394626&doi=10.1175%2fMWR-D-16-0155.1&partnerID=40&md5=84355a64bd6a9e4cf0932edf17766dc2","Understanding phase transitions in mixed-phase clouds is of great importance because the hydrometeor phase controls the lifetime and radiative effects of clouds. In high latitudes, these cloud radiative effects have a crucial impact on the surface energy budget and thus on the evolution of the ice cover. For a springtime low-level mixed-phase stratiform cloud case from Barrow, Alaska, a unique combination of instruments and retrieval methods is combined with multiple modeling perspectives to determine key processes that control cloud phase partitioning. The interplay of local cloud-scale versus large-scale processes is considered. Rapid changes in phase partitioning were found to be caused by several main factors. Major influences were the large-scale advection of different air masses with different aerosol concentrations and humidity content, cloud-scale processes such as a change in the thermodynamical coupling state, and local-scale dynamics influencing the residence time of ice particles. Other factors such as radiative shielding by a cirrus and the influence of the solar cycle were found to only play a minor role for the specific case study (11-12 March 2013). For an even better understanding of cloud phase transitions, observations of key aerosol parameters such as profiles of cloud condensation nucleus and ice nucleus concentration are desirable. © 2016 American Meteorological Society."
"55763374800;57203439874;7005632987;","Aerosol-cloud-precipitation interactions over major cities in south Africa: Impact on regional environment and climate change",2016,"10.4209/aaqr.2015.03.0185","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84952771819&doi=10.4209%2faaqr.2015.03.0185&partnerID=40&md5=f571953e9db9f9dd7a951d900421ffbc","In this study, we have used the Terra satellite onboard of the Moderate Resolution Imaging Spectroradiometer (MODIS) to investigate the spatial and temporal relationship between aerosol optical depth (AOD) and cloud parameters namely, water vapor (WV), cloud optical depth (COD), cloud fraction (CF), cloud effective radius (CER), cloud top pressure (CTP), and cloud top temperature (CTT) based on 10 years (from January 2004 to December 2013) of dataset over six locations in South Africa (SA). The obtained results indicated seasonal variation in AOD, with high values during spring (September to November) and low values in winter (June to August) in all locations of study. In terms of temporal variation, AOD was lowest at Bloemfontein 0.06 ± 0.04 followed by Cape Town 0.08 ± 0.02, then Potchefstroom 0.09 ± 0.05, Pretoria and Skukuza had 0.11 ± 0.05 each and with the highest at Durban 0.13 ± 0.05. The mean Angstrom exponent (AE) values for each location showed a general prevalence of fine-mode particles which dominates the AOD for most parts of the year. A hybrid single particle Lagrangian integrated trajectory (HYSPLIT) model was used for trajectory analysis in order to determine the origin of airmasses and to understand the variability of AOD. We then studied the relationship between AOD, cloud parameters and precipitation over selected locations of SA so as to provide a better understanding of aerosol-cloud-precipitation interactions. All these correlations examined over six sites were observed to be depended on the large-scale meteorological variations. © Taiwan Association for Aerosol Research."
"57190380187;7102128820;56151703900;25624545600;57202531041;","Representing 3-D cloud radiation effects in two-stream schemes: 1. Longwave considerations and effective cloud edge length",2016,"10.1002/2016JD024876","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979539454&doi=10.1002%2f2016JD024876&partnerID=40&md5=892112077cde14bc5a59f77e423bcfbd","Current weather and climate models neglect 3-D radiative transfer through cloud sides, which can change the cloud radiative effect (CRE) significantly. This two-part paper describes the development of the SPeedy Algorithm for Radiative TrAnsfer through CloUd Sides (SPARTACUS) to capture these effects efficiently in a two-stream radiation scheme for use in global models. The present paper concerns the longwave spectral region, where not much work has been done previously, although the limited previous work has suggested that radiative transfer through cloud sides increases the longwave surface CRE of shallow cumulus by around 30%. To assist the development of a longwave capability for SPARTACUS, we use a reference case of an isolated, isothermal, optically thick, cubic cloud in vacuum, for which 3-D effects increase CRE by exactly 200%. It is shown that for any cloud shape, the 3-D effect can be represented in SPARTACUS provided that correct account is made for (1) the effective zenith angle of diffuse radiation emitted from a cloud, (2) the spatial distribution of fluxes in the cloud, (3) cloud clustering that enhances the interception of emitted radiation by neighboring clouds, and (4) radiative smoothing leading to the effective cloud edge length being less than the measured value. We find empirically that the circumference of an ellipse fitted to a horizontal cross section through a cumulus cloud provides a good estimate of the radiatively effective cloud edge length, which provides some guidance to how cloud observations could be analyzed to extract their most important properties for radiation. © 2016. American Geophysical Union. All Rights Reserved."
"55232897900;7402064802;26645289600;","Constraining the low-cloud optical depth feedback at middle and high latitudes using satellite observations",2016,"10.1002/2016JD025233","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983394793&doi=10.1002%2f2016JD025233&partnerID=40&md5=dadbdcf3c758432cfd3313bafec26409","The increase in cloud optical depth with warming at middle and high latitudes is a robust cloud feedback response found across all climate models. This study builds on results that suggest the optical depth response to temperature is timescale invariant for low-level clouds. The timescale invariance allows one to use satellite observations to constrain the models’ optical depth feedbacks. Three passive-sensor satellite retrievals are compared against simulations from eight models from the Atmosphere Model Intercomparison Project (AMIP) of the 5th Coupled Model Intercomparison Project (CMIP5). This study confirms that the low-cloud optical depth response is timescale invariant in the AMIP simulations, generally at latitudes higher than 40°. Compared to satellite estimates, most models overestimate the increase in optical depth with warming at the monthly and interannual timescales. Many models also do not capture the increase in optical depth with estimated inversion strength that is found in all three satellite observations and in previous studies. The discrepancy between models and satellites exists in both hemispheres and in most months of the year. A simple replacement of the models’ optical depth sensitivities with the satellites’ sensitivities reduces the negative shortwave cloud feedback by at least 50% in the 40°-70°S latitude band and by at least 65% in the 40°-70°N latitude band. Based on this analysis of satellite observations, we conclude that the low-cloud optical depth feedback at middle and high latitudes is likely too negative in climate models. © 2016. American Geophysical Union. All Rights Reserved."
"35494005000;57188863155;8600097900;12645767500;6603768446;37111931100;","Retrieving co-occurring cloud and precipitation properties of warm marine boundary layer clouds with A-train data",2016,"10.1002/2015JD023681","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963946884&doi=10.1002%2f2015JD023681&partnerID=40&md5=39356e4a66c4f7548d7deff1d8705cff","In marine boundary layer (MBL) clouds the formation of precipitation from the cloud droplet distribution in the presence of variable aerosol plays a fundamental role in determining the coupling of these clouds to their environment and ultimately to the climate system. Here the degree to which A-Train satellite measurements can diagnose simultaneously occurring cloud and precipitation properties in MBL clouds is examined. Beginning with the measurements provided by CloudSat and Moderate Resolution Imaging Spectroradiometer (including a newly available microwave brightness temperature from CloudSat), and a climatology of MBL cloud properties from past field campaigns, an assumption is made that any hydrometeor volume could contain both cloud droplet and precipitation droplet modes. Bayesian optimal estimation is then used to derive atmospheric states by inverting ameasurement vector carefully accounting for uncertainties due to instrument noise, forward model error, and assumptions. It is found that in many cases where significant precipitation coexists with cloud, due to forward model error driven by uncertainties in assumptions, the uncertainty in retrieved cloud properties is greater than the variance in the prior climatology. It is often necessary to average several thousand (hundred) precipitating (weakly precipitating) profiles to obtain meaningful information regarding the properties important to microphysical processes. Regardless, if such process level information is deemed necessary for better constraining predictive models of the climate system, measurement systems specifically designed to accomplish such retrievals must be considered for the future. © 2016. American Geophysical Union. All Rights Reserved."
"56536745100;36141355100;57203053317;7003748648;","The resolution dependence of cloud effects and ship-induced aerosol-cloud interactions in marine stratocumulus",2016,"10.1002/2015JD024685","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966344397&doi=10.1002%2f2015JD024685&partnerID=40&md5=d5a05fe26449b489be2a47984b0b0e0d","Measures of aerosol-cloud interactions in stratocumulus have been shown to depend on the resolution of the applied data set. In order to contrast resolution with emission dilution effects in models, a regional numerical weather prediction model is used to simulate ship tracks at a range of spatiotemporal resolutions ranging from the global climate modeling scale (Δx = 50 km, Δt = 180 s) to the convection-resolving scale (Δx = 1 km, Δt = 20 s). The background simulations without ship emissions display a high degree of similarity in the planetary boundary layer and cloud properties at all spatiotemporal resolutions. Simulations assessing the impact of emission dilution show an increasing overestimation of the shortwave (SW) cloud radiative effect (CRE) with degenerating emission resolution. Although mean perturbations in the activation-sized aerosol number concentration (Nact) are similar for all dilution experiments, the variability in Nact is increasingly lost with stronger emission dilution. The enhanced Nact homogeneity in turn leads to an overestimated SW CRE. We show that emission dilution alone accounts for 47% of the overestimated SW CRE simulated at low resolutions. The remainder of the differences is attributed to a combination of locally enhanced aerosol concentrations due to weaker vertical mixing simulated at coarse resolutions, in combination with a faster conversion rate of Aitken to accumulation mode particles by redistribution in these regions. © 2016. American Geophysical Union. All rights reserved."
"56883853200;57215596081;","Cloud-radiation feedback as a leading source of uncertainty in the tropical pacific SST warming pattern in CMIP5 models",2016,"10.1175/JCLI-D-15-0796.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983569890&doi=10.1175%2fJCLI-D-15-0796.1&partnerID=40&md5=cd045653ec5a18abd8a86bb86601cc80","The role of the intermodel spread of cloud-radiation feedback in the uncertainty in the tropical Pacific SST warming (TPSW) pattern under global warming is investigated based on the historical and RCP8.5 runs from 32 models participating in CMIP5. The large intermodel discrepancies in cloud-radiation feedback contribute 24% of the intermodel uncertainty in the TPSW pattern over the central Pacific. The mechanism by which the cloud-radiation feedback influences the TPSW pattern is revealed based on an analysis of the surface heat budget. A relatively weak negative cloud-radiation feedback over the central Pacific cannot suppress the surface warming as greatly as in the multimodel ensemble and thus induces a warm SST deviation over the central Pacific, producing a low-level convergence that suppresses (enhances) the evaporative cooling and zonal cold advection in the western (eastern) Pacific. With these processes, the original positive SST deviation over the central Pacific will move westward to the western and central Pacific, with a negative SST deviation in the eastern Pacific. Compared with the observed cloud-radiation feedback from six sets of reanalysis and satellite-observed data, the negative cloud-radiation feedback in the models is underestimated in general. It implies that the TPSW pattern should be closer to an El Niño-like pattern based on the concept of observational constraint. However, the observed cloud-radiation feedback from the various datasets also demonstrates large discrepancies in magnitude. Therefore, the authors suggest that more effort should be made to improve the precision of shortwave radiation observations and the description of cloud-radiation feedback in models for a more reliable projection of the TPSW pattern in future. © 2016 American Meteorological Society."
"55263254000;37016361600;56682032300;26022467200;57189300155;57102736000;57189305836;13403849600;13405658600;7005968859;7004715270;","Ice-nucleating particle emissions from photochemically aged diesel and biodiesel exhaust",2016,"10.1002/2016GL069529","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973124353&doi=10.1002%2f2016GL069529&partnerID=40&md5=576036af411f1cd2786af819d97cb0df","Immersion-mode ice-nucleating particle (INP) concentrations from an off-road diesel engine were measured using a continuous-flow diffusion chamber at −30°C. Both petrodiesel and biodiesel were utilized, and the exhaust was aged up to 1.5 photochemically equivalent days using an oxidative flow reactor. We found that aged and unaged diesel exhaust of both fuels is not likely to contribute to atmospheric INP concentrations at mixed-phase cloud conditions. To explore this further, a new limit-of-detection parameterization for ice nucleation on diesel exhaust was developed. Using a global-chemical transport model, potential black carbon INP (INPBC) concentrations were determined using a current literature INPBC parameterization and the limit-of-detection parameterization. Model outputs indicate that the current literature parameterization likely overemphasizes INPBC concentrations, especially in the Northern Hemisphere. These results highlight the need to integrate new INPBC parameterizations into global climate models as generalized INPBC parameterizations are not valid for diesel exhaust. ©2016. American Geophysical Union. All Rights Reserved."
"56000366900;15069732800;","Verification of cloudiness and radiation forecasts in the greater Alpine region",2016,"10.1127/metz/2015/0630","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959498000&doi=10.1127%2fmetz%2f2015%2f0630&partnerID=40&md5=e627759438979c1e896e8a32c8e87290","The skill of ECMWF operational cloudiness and radiation forecasts is evaluated for the greater Alpine region using ground-based and satellite observations. Ground-based observations are the total cloud cover reported by SYNOP stations. The satellite data we use is the downward surface solar radiation and the top of the atmosphere (TOA) reflected solar radiation from the EUMETSAT Climate Monitoring Satellite Application Facility (CM SAF). A cloud type which is difficult to represent correctly in numerical weather prediction models and which has particular relevance in central Europe is wintertime low stratus. This evaluation shows how it affects forecast skill in mountain areas compared to flat terrain. Results indicate higher skill of the cloud forecast in the Alps compared to the surrounding lowlands throughout the year, with the largest differences in skill occurring in late autumn and early winter. There is also a marked asymmetry in skill between the northern and southern lowlands adjacent to the Alps, which can be attributed to the higher prevalence of low stratus in northern areas. Comparison with other regions shows that cloud forecast skill in Europe is generally high, and that there are large areas of low skill dominated by marine stratus and stratocumulus. © 2015 The authors."
"57201896263;7003543851;","The sensitivity of the hydrological cycle to internal climate variability versus anthropogenic climate change",2016,"10.1175/JCLI-D-15-0408.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009718738&doi=10.1175%2fJCLI-D-15-0408.1&partnerID=40&md5=8dcde9d4c3abdc1c58df1a09b8f82d8e","In response to rising CO2 concentrations, climate models predict that globally averaged precipitation will increase at a much slower rate than water vapor. However, some observational studies suggest that global-mean precipitation and water vapor have increased at similar rates. While the modeling results emphasize changes at multidecadal time scales where the anthropogenic signal dominates, the shorter observational record is more heavily influenced by internal variability. Whether the physical constraints on the hydrological cycle fundamentally differ between these time scales is investigated. The results of this study show that while global-mean precipitation is constrained by radiative cooling on both time scales, the effects of CO2 dominate on multidecadal time scales, acting to suppress the increase in radiative cooling with warming. This results in a smaller precipitation change compared to interannual time scales where the effects of CO2 forcing are small. It is also shown that intermodel spread in the response of atmospheric radiative cooling (and thus global-mean precipitation) to anthropogenically forced surface warming is dominated by clear-sky radiative processes and not clouds, while clouds dominate under internal variability. The findings indicate that the sensitivity of the global hydrological cycle to surface warming differs fundamentally between internal variability and anthropogenically forced changes and this has important implications for interpreting observations of the hydrological sensitivity. © 2016 American Meteorological Society."
"55656250400;7404240633;7404090918;6602929454;8877858700;","Evaluation of ACCESS model cloud properties over the Southern Ocean area using multiple-satellite products",2016,"10.1002/qj.2641","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957842740&doi=10.1002%2fqj.2641&partnerID=40&md5=5e43b42410a1603b7259a51adcf5f267","Radiation field and cloud properties over the Southern Ocean area generated by the Australian Community Climate and Earth System Simulator (ACCESS) are evaluated using multiple-satellite products from the Fast Longwave And Shortwave radiative Fluxes (FLASHFlux) project and NASA/GEWEX surface radiation budget (SRB) data. The cloud properties are also evaluated using the observational simulator package COSP, a synthetic brightness temperature model (SBTM) and cloud liquid-water path data (UWisc) from the University of Wisconsin satellite retrievals. All of these evaluations are focused on the Southern Ocean area in an effort to understand the reasons behind the short-wave radiation biases at the surface. It is found that the model overestimates the high-level cloud fraction and frequency of occurrence of small ice-water content and underestimates the middle and low-level cloud fraction and water content. In order to improve the modelled radiation fields over the Southern Ocean area, two main modifications have been made to the physical schemes in the ACCESS model. Firstly the autoconversion rate at which the cloud water is converted into rain and the accretion rate in the warm rain scheme have been modified, which increases the cloud liquid-water content in warm cloud layers. Secondly, the scheme which determines the fraction of supercooled liquid water in mixed-phase clouds in the parametrization of cloud optical properties has been changed to use one derived from CALIPSO data which provides larger liquid cloud fractions and thus higher optical depths than the default scheme. Sensitivity tests of these two schemes in ACCESS climate runs have shown that applying either can lead to a reduction of the solar radiation reaching the surface and reduce the short-wave radiation biases. © 2016. Royal Meteorological Society."
"55721626100;","The implementation of the Paris agreement in the international and China’s context",2016,"10.3280/EFE2016-003005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030113736&doi=10.3280%2fEFE2016-003005&partnerID=40&md5=e8d2d1f92c7478771aaf705fb0b8e461","With Paris behind us, the focus is now turning to the implementation of the Paris Agreement. This article discusses post-Paris implementation issues both in the international context and in China’s context. These affect the post Paris negotiations and hold the key to achieving desired outcomes. The article ends with some remarks on a cloud cast over climate deal with the unexpected victory of Donald Trump. © FrancoAngeli."
"57191171271;57191166952;56967261800;7006432040;6701316538;","The response of phanerozoic surface temperature to variations in atmospheric oxygen concentration",2016,"10.1002/2016JD025459","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987725248&doi=10.1002%2f2016JD025459&partnerID=40&md5=6b55f3f1050c53c55dbd1086648e4f16","Recently, Poulsen et al. (2015) suggested that O2 has played a major role in climate forcing during the Phanerozoic. Specifically, they argued that decreased O2 levels during the Cenomanian stage of the middle Cretaceous (94-100 Ma) could help explain the extremely warm climate during that time. The postulated warming mechanism involves decreased Rayleigh scattering by a thinner atmosphere, which reduces the planetary albedo and allows greater surface warming. This warming effect is then amplified by cloud feedbacks within their 3-D climate model. This increase in shortwave surface forcing, in their calculations, exceeds any decrease in the greenhouse effect caused by decreased O2. Here we use a 1-D radiative-convective climate model (with no cloud feedback) to check their results. We also include a self-consistent calculation of the change in atmospheric ozone and its effect on climate. Our results are opposite to those of Poulsen et al.: we find that the climate warms by 1.4 K at 35% O2 concentrations as a result of increased pressure broadening of CO2 and H2O absorption lines and cools by 0.8 K at 10% O2 as a result of decreased pressure broadening. The surface temperature changes are only about 1 K either way, though, for reasonable variations in Phanerozoic O2 concentrations (10%-35% by volume). Hence, it seems unlikely that changes in atmospheric O2 account for the warm climate of the Cenomanian. Other factors, such as a higher-than-expected sensitivity of climate to increased CO2 concentrations, may be required to obtain agreement with the paleoclimate data. © 2016. American Geophysical Union."
"7102591209;26659013400;24077600000;57190128706;24168416900;7103016965;26659116700;","The impact of two coupled cirrus microphysics-radiation parameterizations on the temperature and specific humidity biases in the tropical tropopause layer in a climate model",2016,"10.1175/JCLI-D-15-0821.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977508616&doi=10.1175%2fJCLI-D-15-0821.1&partnerID=40&md5=97f4e10ec08a95c5c10d5f9d2a27b9f1","The impact of two different coupled cirrus microphysics-radiation parameterizations on the zonally averaged temperature and humidity biases in the tropical tropopause layer (TTL) of a Met Office climate model configuration is assessed. One parameterization is based on a linear coupling between a model prognostic variable, the ice mass mixing ratio qi, and the integral optical properties. The second is based on the integral optical properties being parameterized as functions of qi and temperature, Tc, where the mass coefficients (i.e., scattering and extinction) are parameterized as nonlinear functions of the ratio between qi and Tc. The cirrus microphysics parameterization is based on a moment estimation parameterization of the particle size distribution (PSD), which relates the mass moment (i.e., second moment if mass is proportional to size raised to the power of 2) of the PSD to all other PSD moments through the magnitude of the second moment and Tc. This same microphysics PSD parameterization is applied to calculate the integral optical properties used in both radiation parameterizations and, thus, ensures PSD and mass consistency between the cirrus microphysics and radiation schemes. In this paper, the temperature-non-dependent and temperature-dependent parameterizations are shown to increase and decrease the zonally averaged temperature biases in the TTL by about 1 K, respectively. The temperature-dependent radiation parameterization is further demonstrated to have a positive impact on the specific humidity biases in the TTL, as well as decreasing the shortwave and longwave biases in the cloudy radiative effect. The temperature-dependent radiation parameterization is shown to be more consistent with TTL and global radiation observations. © 2016 American Meteorological Society."
"55342815900;6506738607;7003875148;57206526682;","The effect of downwelling longwave and shortwave radiation on Arctic summer sea ice",2016,"10.1175/JCLI-D-15-0238.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957818388&doi=10.1175%2fJCLI-D-15-0238.1&partnerID=40&md5=72572fc4016892d3f6069ad4b6cc1de6","The Arctic summer sea ice has diminished fast in recent decades.Astrong year-to-year variability on top of this trend indicates that sea ice is sensitive to short-term climate fluctuations. Previous studies show that anomalous atmospheric conditions over the Arctic during spring and summer affect ice melt and the September sea ice extent (SIE). These conditions are characterized by clouds, humidity, and heat anomalies that all affect downwelling shortwave (SWD) and longwave (LWD) radiation to the surface. In general, positive LWD anomalies are associated with cloudy and humid conditions, whereas positive anomalies of SWD appear under clear-sky conditions. Here the effect of realistic anomalies ofLWDandSWDon summer sea ice is investigated by performing experiments with the Community Earth System Model. The SWD and LWD anomalies are studied separately and in combination for different seasons. It is found that positive LWD anomalies in spring and early summer have significant impact on the September SIE, whereas winter anomalies show only little effect. Positive anomalies in spring and early summer initiate an earlier melt onset, hereby triggering several feedback mechanisms that amplify melt during the succeeding months. Realistic positive SWD anomalies appear only important if they occur after the melt has started and the albedo is significantly reduced relative to winter conditions. Simulations where both positive LWD and negative SWD anomalies are implemented simultaneously, mimicking cloudy conditions, reveal that clouds during spring have a significant impact on summer sea ice while summer clouds have almost no effect. © 2016 American Meteorological Society."
"7102203311;25222013700;57202917221;8670472000;","Spatial and temporal characteristics of summer precipitation over central Europe in a suite of high-resolution climate models",2016,"10.1175/JCLI-D-15-0463.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013480083&doi=10.1175%2fJCLI-D-15-0463.1&partnerID=40&md5=6b8a398c6dadb2dcdaefdeaeb95a08d7","High-impact, locally intense rainfall episodes represent a major socioeconomic problem for societies worldwide, and at the same time these events are notoriously difficult to simulate properly in climate models. Here, the authors investigate how horizontal resolution and model formulation influence this issue by applying the HIRLAM-ALADIN Regional Mesoscale Operational NWP in Europe (HARMONIE) Climate (HCLIM) regional model with three different setups: two using convection parameterization at 15- and 6.25-km horizontal resolution (the latter within the ""gray zone"" scale), with lateral boundary conditions provided by ERA-Interim and integrated over a pan-European domain, and one with explicit convection at 2-km resolution (HCLIM2) over the Alpine region driven by the 15-km model. Seven summer seasons were sampled and validated against two high-resolution observational datasets. All HCLIM versions underestimate the number of dry days and hours by 20%-40% and overestimate precipitation over the Alpine ridge. Also, only modest added value was found for gray-zone resolution. However, the single most important outcome is the substantial added value in HCLIM2 compared to the coarser model versions at subdaily time scales. It better captures the local-to-regional spatial patterns of precipitation reflecting a more realistic representation of the local and mesoscale dynamics. Further, the duration and spatial frequency of precipitation events, as well as extremes, are closer to observations. These characteristics are key ingredients in heavy rainfall events and associated flash floods, and the outstanding results using HCLIM in a convection-permitting setting are convincing and encourage further use of the model to study changes in such events in changing climates. © 2016 American Meteorological Society."
"38863214100;7102011703;55656837900;","Monotonic decrease of the zonal SST gradient of the equatorial pacific as a function of CO2 concentration in CCSM3 and CCSM4",2016,"10.1002/2016JD025231","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989298047&doi=10.1002%2f2016JD025231&partnerID=40&md5=b42a0c439cd982cf44a4398aff759ecb","The west-east sea surface temperature (SST) gradient in the equatorial Pacific Ocean is a key feature of Earth’s climate. How this gradient responds to varying climatic forcing is a challenge to both climate theory and climate modeling. Using the coupled atmosphere-ocean general circulation models, Community Climate System Model version 3 (CCSM3) and version 4 (CCSM4), we show that the zonal SST gradient is an almost monotonically decreasing function of atmospheric CO2 concentration (pCO2) across a wide range from 17.5 to 4576 ppmv. As pCO2 is increased, the optical depth of clouds over the western and central Pacific increases significantly, reflecting more insolation back to space, suppressing surface warming in this region and thereby reducing the zonal SST gradient. Ocean adjustment to a weakening of surface zonal winds is characterized by relaxations of the equatorial thermocline tilt, zonal surface currents, and ocean upwelling. © 2016. American Geophysical Union. All Rights Reserved."
"55703847000;7601492669;7103060756;8718425100;","Dynamical downscaling of the climate for the Hawaiian islands. Part II: Projection for the late twenty-first century",2016,"10.1175/JCLI-D-16-0038.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84996606695&doi=10.1175%2fJCLI-D-16-0038.1&partnerID=40&md5=9dfaa528d93b3f0c6a965b99bce7e700","A 20-yr simulation with a fine-resolution regional atmospheric model for projected late twenty-first-century conditions in Hawaii is presented. The pseudo-global-warming method is employed, and the boundary conditions are based on a multimodel mean of projections made with global coupled models run with a moderate greenhouse gas emissions scenario. Results show that surface air temperature over land increases ~2°-4°C with the greatest warming at the highest topographic heights. A modest tendency for the warming to be larger on the leeward sides of the major islands is also apparent. Climatological rainfall is projected to change up to ~25% at many locations. The currently wet windward sides of the major islands will have more clouds and receive more rainfall, while the currently dry leeward sides will generally have even less clouds and rainfall. The average trade wind inversion-base height and the mean marine boundary layer cloud heights are projected to exhibit only small changes. However, the frequency of days with clearly defined trade wind inversions is predicted to increase substantially (~83% to ~91%). The extreme rainfall events are projected to increase significantly. An analysis of the model's moisture budget in the lower troposphere shows that the increased mean rainfall on the windward sides of the islands is largely attributable to increased boundary layer moisture in the warmer climate. Rainfall changes attributable to mean low-level circulation changes are modest in comparison. © 2016 American Meteorological Society."
"56265041500;6602574676;57203297300;6603453147;36098286300;","Radiative characteristics of clouds embedded in smoke derived from airborne multiangular measurements",2016,"10.1002/2016JD025309","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982938375&doi=10.1002%2f2016JD025309&partnerID=40&md5=4e90d5927460d78ca3d501fb4748a324","Clouds in the presence of absorbing aerosols result in their apparent darkening, observed at the top of atmosphere (TOA), which is associated with the radiative effects of aerosol absorption. Owing to the large radiative effect and potential impacts on regional climate, above-cloud aerosols have recently been characterized in multiple satellite-based studies. While satellite data are particularly useful in showing the radiative impact of above-cloud aerosols at the TOA, recent literature indicates large uncertainties in satellite retrievals of above-cloud aerosol optical depth (AOD) and single scattering albedo (SSA), which are among the most important parameters in the assessment of associated radiative effects. In this study, we analyze radiative characteristics of clouds in the presence of wildfire smoke using airborne data primarily from NASA’s Cloud Absorption Radiometer, collected during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites campaign in Canada during the 2008 summer season. We found a strong positive reflectance (R) gradient in the UV-visible (VIS)-near infrared (NIR) spectrum for clouds embedded in dense smoke, as opposed to an (expected) negative gradient for cloud-free smoke and a flat spectrum for smoke-free cloud cover. Several cases of clouds embedded in thick smoke were found, when the aircraft made circular/spiral measurements, which not only allowed the complete characterization of angular distribution of smoke scattering but also provided the vertical distribution of smoke and clouds (within 0.5-5 km). Specifically, the largest darkening by smoke was found in the UV/VIS, with R0.34µm reducing to 0.2 (or 20%), in contrast to 0.8 at NIR wavelengths (e.g., 1.27 µm). The observed darkening is associated with large AODs (0.5-3.0) and moderately low SSA (0.85-0.93 at 0.53 µm), resulting in a significantly large instantaneous aerosol forcing efficiency of 254 ± 47Wm-2 τ-1. Our observations of smoke-cloud radiative interactions were found to be physically consistent with theoretical plane-parallel 1-D and Monte Carlo 3-D radiative transfer calculations, capturing the observed gradient across UV-VIS-NIR. Results from this study offer insights into aerosol-cloud radiative interactions and may help in better constraining satellite retrieval algorithms. © 2016. American Geophysical Union. All Rights Reserved."
"55747560500;12769875100;","Evaluation of the Arctic surface radiation budget in CMIP5 models",2016,"10.1002/2016JD025099","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979306902&doi=10.1002%2f2016JD025099&partnerID=40&md5=ae1393fa52196b20779c83f49121a3a4","The Arctic region is warming at a rate more than double the global average, a trend predicted to continue by all Coupled Model Intercomparison Project 5 (CMIP5) climate models. Despite this consistency, significant intermodel spread exists in the simulated Arctic climate related to differences in the Arctic surface radiation budget. Building upon previous work to characterize and understand surface radiation budget biases in climate models, the annual mean and seasonal cycle of the Arctic surface radiation budget in 17 CMIP5 models using the Historical-forcing scenario is evaluated against state-of-the-art Cloud and Earth’s Radiant Energy System Surface Energy Balanced and Filled data. The CMIP5 multimodel ensemble is found to simulate longwave surface fluxes well during the sunlit months (~1Wm-2 differences in July) but exhibits significant wintertime biases (up to -19Wm-2). Shortwave fluxes show substantial across-model spread during summer; the model standard deviation approaches 20Wm-2 in July. Applying a decomposition analysis to the cloud radiative effect (CRE) seasonal cycles, an unrealistic compensation is uncovered between the model-simulated seasonal cycles of cloud fraction, all-sky/clear-sky flux differences, and surface albedo that enables models to simulate realistic CRE seasonal cycles with unrealistic individual contributions. This unrealistic behavior in models must be constrained to improve Arctic climate simulation; observational uncertainty is sufficient to do so. Lastly, biases in all and clear-sky longwave downwelling fluxes positively correlate with model surface temperature in winter, while in summer surface temperature is most strongly related to clear-sky upwelling radiation biases from surface albedo errors. © 2016. American Geophysical Union. All Rights Reserved."
"9249239700;57144839900;7501439334;7003278104;36150977900;56130997600;57044397100;6603126554;54787680700;","The impacts of precipitating cloud radiative effects on ocean surface evaporation, precipitation, and ocean salinity in coupled GCM simulations",2016,"10.1002/2016JD024911","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983407620&doi=10.1002%2f2016JD024911&partnerID=40&md5=898a0316110fd113bef262a3093affc4","The coupled global climate model (GCM) fidelity in representing upper ocean salinity including near sea surface bulk salinity (SSS) is evaluated in this study, with a focus on the Pacific Ocean. The systematic biases in ocean surface evaporation (E) minus precipitation (P) and SSS are found to be fairly similar in the twentieth century simulations of the Coupled Model Intercomparison Phase 3 (CMIP3) and Phase 5 (CMIP5) relative to the observations. One of the potential causes of the CMIP model biases is the missing representation of the radiative effects of precipitating hydrometeors (i.e., snow) in most CMIP models. To examine the radiative effect of cloud snow on SSS, sensitivity experiments with and without such effect are conducted by the National Center for Atmospheric Research-coupled Community Earth System Model (CESM). This study investigates the difference in SSS between sensitivity experiments and its relationship with atmospheric circulation, E-P and air-sea heat fluxes. It is found that the exclusion of the cloud snow radiative effect in CESM produces weaker Pacific trade winds, resulting in enhanced precipitation, reduced evaporation, and a reduction of the upper ocean salinity in the tropical and subtropical Pacific. The latter results in an improved comparison with climatological upper ocean bulk salinity. The introduction of cloud snow also altered the budget terms that maintain the time-mean salinity in the mixed layer. © 2016. American Geophysical Union. All Rights Reserved."
"56120519800;7103016965;6603871013;7801353107;24764483400;","A parametrization of subgrid orographic rain enhancement via the seeder-feeder effect",2016,"10.1002/qj.2637","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957839864&doi=10.1002%2fqj.2637&partnerID=40&md5=259267638a9382890c43d2f92df325c1","Numerical models used for low-resolution weather and climate simulations are unable to produce enough orographic rain enhancement via the seeder-feeder effect during the passage of frontal systems when the orography is not sufficiently well represented. This article describes the development of a simple parametrization scheme to remedy this problem. The scheme estimates the increase in the grid-box mean cloud liquid-water mixing ratio that would result from vertical displacements produced by unresolved hills, accounting for regions where the actual surface is both higher and lower than the model surface. Using idealized two-dimensional simulations of neutrally stratified flow over a Gaussian-shaped ridge resolved to varying degrees, the new scheme was shown to increase the total (resolved plus parametrized) orographic water towards that produced over a well-resolved hill, with good agreement for a wide range of hill sizes. This subgrid orographic water can be used by a microphysics parametrization scheme to enhance the growth of rain (or snow) via accretion. In simulations with a constant rain rate into the top of the domain, the surface orographic rain rate was increased over a small completely subgrid hill by up to 90%, giving much better agreement with the simulations over a well-resolved hill. The scheme also increases the rain produced by flow over large subgrid mountains if the resolved cloud is able to produce some rain via autoconversion. © 2016 Royal Meteorological Society."
"55268661300;55461837700;","Observed signatures of the barotropic and baroclinic annular modes in cloud vertical structure and cloud radiative effects",2016,"10.1175/JCLI-D-15-0692.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977513121&doi=10.1175%2fJCLI-D-15-0692.1&partnerID=40&md5=b9a266fbc4ce1cf0868c265d31d346d9","The signatures of large-scale annular variability on the vertical structure of clouds and cloud radiative effects are examined in vertically resolved CloudSat and other satellite and reanalysis data products. The northern and southern ""barotropic"" annular modes (the NAM and SAM) have a complex vertical structure. Both are associated with a meridional dipole in clouds between subpolar and middle latitudes, but the sign of the anomalies changes between upper, middle, and lower tropospheric levels. In contrast, the northern and southern baroclinic annular modes have a much simpler vertical structure. Both are linked to same-signed anomalies in clouds extending throughout the troposphere at middle to high latitudes. The changes in cloud incidence associated with both the barotropic and baroclinic annular modes are consistent with dynamical forcing by the attendant changes in static stability and/or vertical motion. The results also provide the first observational estimates of the vertically resolved atmospheric cloud radiative effects associated with hemispheric-scale extratropical variability. In general, the anomalies in atmospheric cloud radiative effects associated with the annular modes peak in the middle to upper troposphere, and are consistent with the anomalous trapping of longwave radiation by variations in upper tropospheric clouds. The southern baroclinic annular mode gives rise to periodic behavior in longwave cloud radiative effects at the top of the atmosphere averaged over Southern Hemisphere midlatitudes. © 2016 American Meteorological Society."
"56377079900;10540061400;7005977764;56495567600;6603550210;","Water balance and level change of lake Babati, Tanzania: Sensitivity to hydroclimatic forcings",2016,"10.3390/w8120572","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010383469&doi=10.3390%2fw8120572&partnerID=40&md5=3e4710b32e8e230b5809ff5d943384ee","We develop and present a novel integrated water balance model that accounts for lake water-groundwater interactions, and apply it to the semi-closed freshwater Lake Babati system, Northern Tanzania, East Africa. The model was calibrated and used to evaluate the lake level sensitivity to changes in key hydro-climatic variables such as temperature, precipitation, humidity and cloudiness. The lake response to the Coupled Model Intercomparison Project, Phase 5 (CMIP5) output on possible future climate outcomes was evaluated, an essential basis in understanding future water security and flooding risk in the region. Results show high lake level sensitivity to cloudiness. Increased focus on cloud fraction measurement and interpretation could likely improve projections of lake levels and surface water availability. Modelled divergent results on the future (21st century) development of Lake Babati can be explained by the precipitation output variability of CMIP5 models being comparable to the precipitation change needed to drive the water balance model from lake dry-out to overflow; this condition is likely shared with many other East African lake systems. The developed methodology could be useful in investigations on change-driving processes in complex climate-drainage basin-lake systems, which are needed to support sustainable water resource planning in data scarce tropical Africa. © 2016 by the authors."
"24528108000;44061090200;35547807400;","An intensified hydrological cycle in the simulation of geoengineering by cirrus cloud thinning using ice crystal fall speed changes",2016,"10.1002/2015JD024304","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977501539&doi=10.1002%2f2015JD024304&partnerID=40&md5=5b4d5b59e4dbe8ab9577b5ab5466fb0c","Proposals to geoengineer Earth’s climate by cirrus cloud thinning (CCT) potentially offer advantages over solar radiation management schemes: amplified cooling of the Arctic and smaller perturbations to global mean precipitation in particular. Using an idealized climate model implementation of CCT in which ice particle fall speeds were increased 2×, 4×, and 8× we examine the relationships between effective radiative forcing (ERF) at the top of atmosphere, near-surface temperature, and the response of the hydrological cycle. ERF was nonlinear with fall speed change and driven by the trade-off between opposing positive shortwave and negative longwave radiative forcings. ERF was-2.0Wm-2 for both 4× and 8× fall speeds. Global mean temperature decreased linearly with ERF, while Arctic temperature reductions were amplified compared with the global mean change. The change in global mean precipitation involved a rapid adjustment (~ 1%/Wm2), which was linear with the change in the net atmospheric energy balance, and a feedback response (~2%/°C). Global mean precipitation and evaporation increased strongly in the first year of CCT. Intensification of the hydrological cycle was promoted by intensification of the vertical overturning circulation of the atmosphere, changes in boundary layer climate favorable for evaporation, and increased energy available at the surface for evaporation (from increased net shortwave radiation and reduced subsurface storage of heat). Such intensification of the hydrological cycle is a significant side effect to the cooling of climate by CCT. Any accompanying negative cirrus cloud feedback response would implicitly increase the costs and complexity of CCT deployment. © 2016. The Authors."
"7006614696;36907291300;","Convective and large-scalemass flux profiles over tropical oceans determined fromsynergistic analysis of a suite of satellite observations",2016,"10.1002/2016JD024753","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978878010&doi=10.1002%2f2016JD024753&partnerID=40&md5=801e775370dbb42d3c4b8cc98d9a7fa5","A new, satellite-based methodology is developed to evaluate convective mass flux and large-scale total mass flux. To derive the convective mass flux, candidate profiles of in-cloud vertical velocity are first constructed with a simple plume model under the constraint of ambient sounding and then narrowed down to the solution that matches satellite-derived cloud top buoyancy. Meanwhile, the large-scale total mass flux is provided separately from satellite soundings by a method developed previously. All satellite snapshots are sorted into a composite time series that delineates the evolution of a vigorous and organized convective system. Principal findings are the following. First, convective mass flux is modulated primarily by convective cloud cover, with the intensity of individual convection being less variable over time. Second, convective mass flux dominates the total mass flux only during the early hours of the convective evolution; as convective system matures, a residual mass flux builds up in the mass flux balance that is reminiscent of stratiform dynamics. The method developed in this study is expected to be of unique utility for future observational diagnosis of tropical convective dynamics and for evaluation of global climate model cumulus parameterizations in a global sense. © 2016. The Authors."
"22980035400;57202615463;8658386900;37018824600;7006446865;6506385754;","Polarimetric radar and aircraft observations of saggy bright bands during MC3E",2016,"10.1002/2015JD024446","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963904768&doi=10.1002%2f2015JD024446&partnerID=40&md5=44088711642ce321b2b24bca63290ece","Polarimetric radar observations increasingly are used to understand cloud microphysical processes, which is critical for improving their representation in cloud and climate models. In particular, there has been recent focus on improving representations of ice collection processes (e.g., aggregation and riming), as these influence precipitation rate, heating profiles, and ultimately cloud life cycles. However, distinguishing these processes using conventional polarimetric radar observations is difficult, as they produce similar fingerprints. This necessitates improved analysis techniques and integration of complementary data sources. The Midlatitude Continental Convective Clouds Experiment (MC3E) provided such an opportunity. Quasi-vertical profiles of polarimetric radar variables in two MC3E stratiform precipitation events reveal episodic melting layer sagging. Integrated analyses using scanning and vertically pointing radar and aircraft measurements reveal that saggy bright band signatures are produced when denser, faster-falling, more isometric hydrometeors (relative to adjacent times) descend into the melting layer. In one case, strong circumstantial evidence for riming is found during bright band sagging times. A bin microphysical melting layer model successfully reproduces many aspects of the signature, supporting the observational analysis. If found to be a reliable indicator of riming, saggy bright bands could be a proxy for the presence of supercooled liquid water in stratiform precipitation, which may provid. © 2016. American Geophysical Union. All Rights Reserved."
"35768617200;6603562975;7005126327;7102581856;6505732261;57191330729;6701772538;8719703500;7006717176;7004678728;","In situ and space-based observations of the Kelud volcanic plume: The persistence of ash in the lower stratosphere",2016,"10.1002/2016JD025344","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988847810&doi=10.1002%2f2016JD025344&partnerID=40&md5=517035677cf6311224b75af343205388","Volcanic eruptions are important causes of natural variability in the climate system at all time scales. Assessments of the climate impact of volcanic eruptions by climate models almost universally assume that sulfate aerosol is the only radiatively active volcanic material. We report satellite observations from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite after the eruption of Mount Kelud (Indonesia) on 13 February 2014 of volcanic materials in the lower stratosphere. Using these observations along with in situ measurements with the Compact Optical Backscatter AerosoL Detector (COBALD) backscatter sondes and optical particle counters (OPCs) made during a balloon field campaign in northern Australia, we find that fine ash particles with a radius below 0.3 μm likely represented between 20 and 28% of the total volcanic cloud aerosol optical depth 3 months after the eruption. A separation of 1.5–2 km between the ash and sulfate plumes is observed in the CALIOP extinction profiles as well as in the aerosol number concentration measurements of the OPC after 3 months. The settling velocity of fine ash with a radius of 0.3 μm in the tropical lower stratosphere is reduced by 50% due to the upward motion of the Brewer-Dobson circulation resulting a doubling of its lifetime. Three months after the eruption, we find a mean tropical clear-sky radiative forcing at the top of the atmosphere from the Kelud plume near 0.08 W/m2 after including the presence of ash; a value ~20% higher than if sulfate alone is considered. Thus, surface cooling following volcanic eruptions could be affected by the persistence of ash and should be considered in climate simulations. © 2016. The Authors."
"56188306800;7409080503;55806891500;8839875600;","Impact of aerosols on precipitation from deep convective clouds in eastern China",2016,"10.1002/2015JD024246","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983558972&doi=10.1002%2f2015JD024246&partnerID=40&md5=09f8c7f8a2ef8293d144d9d03cc14eab","We analyzed the impact of aerosols on precipitation based on 3 years of 3-hourly observations made in heavily polluted eastern China. The probability of precipitation from different cloud types was calculated using International Satellite Cloud Climatology Project cloud data and gauge-based hourly precipitation data. Because deep convective clouds have the largest precipitation probability, the influence of aerosols on the precipitation from such clouds was studied in particular. Aerosol properties were taken from the Modern-Era Retrospective Analysis for Research and Applications Aerosol Reanalysis data set. As aerosol optical depth increased, rainfall amounts from deep convective clouds increased at first and then decreased. The descending part of the trend is likely due to the aerosol radiative effect. Downwelling solar radiative fluxes at the surface decreased as aerosol optical depth increased. The decrease in solar radiation led to a decrease in ground heat fluxes and convective available potential energy, which is unfavorable for development of convective clouds and precipitation. The tendencies for lower cloud top temperatures, lower cloud top pressures, and higher cloud optical depths as a response to larger aerosol optical depths suggest the invigoration effect. Vertical velocity, relative humidity, and air temperature from the National Centers for Environmental Prediction Climate Forecast System Reanalysis were sorted to help investigate if the trends are dependent on any environmental conditions. How dynamic and microphysical factors strengthen or mitigate the impact of aerosols on clouds and precipitation and more details about their interplay should be studied further using more observations and model simulations. © 2016. American Geophysical Union. All Rights Reserved."
"57188817814;24472110700;7102425008;7003875148;","Summer Arctic clouds in the ECMWF forecast model: An evaluation of cloud parametrization schemes",2016,"10.1002/qj.2658","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957849655&doi=10.1002%2fqj.2658&partnerID=40&md5=1da482e18939ea7c235739874eba0f46","Mixed-phase clouds are an integral part of the Arctic climate system, for precipitation and for their interactions with radiation and thermodynamics. Mixed-phase processes are often poorly represented in global models and many use an empirically based diagnostic partition between the liquid and ice phases that is dependent solely on temperature. However, increasingly more complex microphysical parametrizations are being implemented allowing a more physical representation of mixed-phase clouds. This study uses in situ observations from the Arctic Summer Cloud Ocean Study (ASCOS) field campaign in the central Arctic to assess the impact of a change from a diagnostic to a prognostic parametrization of mixed-phase clouds and increased vertical resolution in the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS). The newer cloud scheme improves the representation of the vertical structure of mixed-phase clouds, with supercooled liquid water at cloud top and ice precipitating below, improved further with higher vertical resolution. Increased supercooled liquid water and decreased ice content are both in closer agreement with observations. However, these changes do not result in any substantial improvement in surface radiation, and a warm and moist bias in the lowest part of the atmosphere remains. Both schemes also fail to capture the transitions from overcast to cloud-free conditions. Moreover, whereas the observed cloud layer is frequently decoupled from the surface, the modelled clouds remain coupled to the surface most of the time. The changes implemented to the cloud scheme are an important step forward in improving the representation of Arctic clouds, but improvements in other aspects such as boundary-layer turbulence, cloud radiative properties, sensitivity to low aerosol concentrations and representation of the sea-ice surface may also need to be addressed. © 2016 Royal Meteorological Society."
"57092467500;","The aerosol-monsoon climate system of Asia: A new paradigm",2016,"10.1007/s13351-015-5999-1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007277317&doi=10.1007%2fs13351-015-5999-1&partnerID=40&md5=def28e176ac749a94fe6ce6bace34c4a","This commentary is based on a series of recent lectures on aerosol-monsoon interactions I gave at the Beijing Normal University in August 2015. A main theme of the lectures is on a new paradigm of “An Aerosol-Monsoon-Climate-System”, which posits that aerosol, like rainfall, cloud, and wind, is an integral component of the monsoon climate system, influencing monsoon weather and climate on all timescales. Here, salient issues discussed in my lectures and my personal perspective regarding interactions between atmospheric dynamics and aerosols from both natural and anthropogenic sources are summarized. My hope is that under this new paradigm, we can break down traditional disciplinary barriers, advance a deeper understanding of weather and climate in monsoon regions, as well as entrain a new generation of geoscientists to strive for a sustainable future for one of the most complex and challenging human-natural climate sub-system of the earth. © The Chinese Meteorological Society and Springer-Verlag Berlin Heidelberg 2016."
"55968129100;7401795483;57190854861;","Heavy rainfall prediction applying satellite-based cloud data assimilation over land",2016,"10.1002/2016JD025291","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983527034&doi=10.1002%2f2016JD025291&partnerID=40&md5=8ee57d6bbaaf66e27968fa4123b06c79","To optimize flood management, it is crucial to determine whether rain will fall within a river basin. This requires very fine precision in prediction of rainfall areas. Cloud data assimilation has great potential to improve the prediction of precipitation area because it can directly obtain information on locations of rain systems. Clouds can be observed globally by satellite-based microwave remote sensing. Microwave observation also includes information of latent heat and water vapor associated with cloud amount, which enables the assimilation of not only cloud itself but also the cloud-affected atmosphere. However, it is difficult to observe clouds over land using satellite microwave remote sensing, because their emissivity is much lower than that of the land surface. To overcome this challenge, we need appropriate representation of heterogeneous land emissivity. We developed a coupled atmosphere and land data assimilation system with the Weather Research and Forecasting Model (CALDAS-WRF), which can assimilate soil moisture, vertically integrated cloud water content over land, and heat and moisture within clouds simultaneously. We applied this system to heavy rain events in Japan. Results show that the system effectively assimilated cloud signals and produced very accurate cloud and precipitation distributions. The system also accurately formed a consistent atmospheric field around the cloud. Precipitation intensity was also substantially improved by appropriately representing the local atmospheric field. Furthermore, combination of the method and operationally analyzed dynamical and moisture fields improved prediction of precipitation duration. The results demonstrate the method’s promise in dramatically improving predictions of heavy rain and consequent flooding. © 2016. American Geophysical Union. All Rights Reserved."
"56640482500;7404765381;","Cloud impacts on pavement temperature and shortwave radiation",2016,"10.1175/JAMC-D-16-0094.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84998591776&doi=10.1175%2fJAMC-D-16-0094.1&partnerID=40&md5=2da08c0ce586835a54679880ccb47e79","Forecast systems provide decision support for end users ranging from the solar energy industry to municipalities concerned with road safety. Pavement temperature is an important variable when considering vehicle response to various weather conditions. A complex relationship exists between tire and pavement temperatures that affects vehicle performance. Many forecast systems suffer from inaccurate radiation forecasts resulting in part from the inability to model different types of clouds and their influence on radiation. This research focuses on forecast improvement by determining how cloud type impacts pavement temperature and the amount of shortwave radiation reaching the surface. The study region is the Great Plains where surface radiation data were obtained from the High Plains Regional Climate Center's Automated Weather Data Network stations. Pavement temperature data were obtained from the Meteorological Assimilation Data Ingest System. Cloud-type identification was possible via the Naval Research Laboratory Cloud Classification algorithm, and clouds were subsequently sorted into five distinct groups: clear conditions, low clouds, middle clouds, high clouds, and cumuliform clouds. Statistical analyses during the daytime in June 2011 revealed that cloud cover lowered pavement temperatures by up to approximately 10°C and dampened downwelling shortwave radiation by up to 400 W m-2. These pavement temperatures and surface radiation observations were strongly correlated, with a maximum correlation coefficient of 0.83. A comparison between cloud-type group identified and cloud cover observed from satellite images provided a measure of confidence in the results and identified cautions with using satellite-based cloud detection. © 2016 American Meteorological Society."
"54999243300;7102963655;7003696273;7003479145;","Evaluating the diurnal cycle of upper tropospheric humidity in two different climate models using satellite observations",2016,"10.3390/rs8040325","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971635809&doi=10.3390%2frs8040325&partnerID=40&md5=ed9970a3f45f538ceba3c812a3ed8077","The diurnal cycle of upper tropospheric humidity (UTH) is known to be influenced by such processes as convection and the formation of clouds which are parameterized in current global climate models. In this study, we evaluate the performance of two climate models, the Community Atmospheric Model version 5 (CAM-5) and the Global Atmosphere 3.0 (GA-3) model in simulating the diurnal cycle of UTH (represented by a combination of sinusoids of 12 and 24 h periods) by comparing with microwave and infrared (IR) measurements (where available). These comparisons were made over two convective land regions in South America and Africa, and over oceanic regions in the Atlantic, Indian and West Pacific for the month of January 2007. We analyzed how the diurnal cycles from IR and microwave instruments differ, and the reason for the differences. Our study suggests that the differences in the diurnal cycles of IR and microwave UTH result from sampling differences due to the presence of clouds. As noted by earlier studies, the models exhibit considerable discrepancies in diurnal amplitude and phase relative to observations, and these discrepancies have different magnitudes over land and ocean. © 2016 by the authors."
"56297863500;7202208382;6701835010;","Dark warming",2016,"10.1175/JCLI-D-15-0147.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957827830&doi=10.1175%2fJCLI-D-15-0147.1&partnerID=40&md5=3b65a460a66bf739ffb701e059c805fa","As the Arctic sea ice thins and ultimately disappears in a warming climate, its insulating power decreases. This causes the surface air temperature to approach the temperature of the relatively warm ocean water below the ice. The resulting increases in air temperature, water vapor, and cloudiness lead to an increase in the surface downwelling longwave radiation (DLR), which enables a further thinning of the ice. This positive ice- insulation feedback operates mainly in the autumn and winter. A climate change simulation with the Community Earth System Model shows that, averaged over the year, the increase in ArcticDLRis 3 times stronger than the increase in Arctic absorbed solar radiation at the surface. The warming of the surface air over the Arctic Ocean during fall and winter creates a strong thermal contrast with the colder surrounding continents. Sea level pressure falls over the Arctic Ocean, and the high-latitude circulation reorganizes into a shallow ''winter monsoon.'' The resulting increase in surface wind speed promotes stronger surface evaporation and higher humidity over portions of the Arctic Ocean, thus reinforcing the ice-insulation feedback. © 2016 American Meteorological Society."
[No author id available],"Major issues of air pollution",2016,"10.1007/978-3-319-21596-9_1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84940186562&doi=10.1007%2f978-3-319-21596-9_1&partnerID=40&md5=806c4940cdb4f4d1bd3c65e981920ff2","Environmental issues change from place to place and time to time. The issues include local as well as global issues. The understanding of issues is necessary to find solution. Air pollution issues have changed over a period of time. Issues like atmospheric brown cloud, climate change, hazardous air pollutants, black/muddy snow which are hardly discussed few decades back have now gaining importance. This chapter elaborates major issues due to air pollution. © Springer International Publishing Switzerland 2016"
"7006329853;56016057500;7006686129;7003729315;57203052274;7202081585;57194114573;35494005000;16402575500;35459699300;57205479513;6602137800;7404548584;7404462897;57192810488;6604054503;7006783796;35263854800;6603758021;6701738768;","Planning, implementation, and scientific goals of the studies of emissions and atmospheric composition, clouds and climate coupling by regional surveys (SEAC4RS) field mission",2016,"10.1002/2015JD024297","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964444571&doi=10.1002%2f2015JD024297&partnerID=40&md5=2cb9b684ce408e15e96f253bf4fa8417","The Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) fieldmission based at Ellington Field, Texas, during August and September 2013 employed the most comprehensive airborne payload to date to investigate atmospheric composition over North America. The NASA ER-2, DC-8, and SPEC Inc. Learjet flew 57 science flights fromthe surface to 20 km. The ER-2 employed seven remote sensing instruments as a satellite surrogate and eight in situ instruments. The DC-8 employed 23 in situ and five remote sensing instruments for radiation, chemistry, and microphysics. The Learjet used 11 instruments to explore cloud microphysics. SEAC4RS launched numerous balloons, augmented AErosol RObotic NETwork, and collaborated with many existing ground measurement sites. Flights investigating convection included close coordination of all three aircraft. Coordinated DC-8 and ER-2 flights investigated the optical properties of aerosols, the influence of aerosols on clouds, and the performance of new instruments for satellite measurements of clouds and aerosols. ER-2 sorties sampled stratospheric injections of water vapor and other chemicals by local and distant convection. DC-8 flights studied seasonally evolving chemistry in the Southeastern U.S., atmospheric chemistry with lower emissions of NOx and SO2 than in previous decades, isoprene chemistry under high and low NOx conditions at different locations, organic aerosols, air pollution near Houston and in petroleum fields, smoke from wildfires in western forests and from agricultural fires in the Mississippi Valley, and the ways in which the chemistry in the boundary layer and the upper troposphere were influenced by vertical transport in convective clouds. © 2016. American Geophysical Union. All rights reserved."
"57202055245;6602725432;7003811754;7102084129;7101959253;7004242319;6701754792;","What is the role of sea surface temperature in modulating cloud and precipitation properties over the Southern Ocean?",2016,"10.1175/JCLI-D-15-0768.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84993995769&doi=10.1175%2fJCLI-D-15-0768.1&partnerID=40&md5=04f80384b0957ed2db7088acbaa0fc3f","This study employs four years of spatiotemporally collocated A-Train satellite observations to investigate cloud and precipitation characteristics in relation to the underlying properties of the Southern Ocean (SO). Results show that liquid-phase cloud properties strongly correlate with the sea surface temperature (SST). In summer, ubiquitous supercooled liquid water (SLW) is observed over SSTs less than about 4°C. Cloud-top temperature (CTT) and effective radius of liquid-phase clouds generally decrease for colder SSTs, whereas the opposite trend is observed for cloud-top height, cloud optical thickness, and liquid water path. The deduced cloud depth is larger over the colder oceans. Notable differences are observed between ""precipitating"" and ""nonprecipitating"" clouds and between different ocean sectors. Using a novel joint SST-CTT histogram, two distinct liquid-phase cloud types are identified, where the retrieved particle size appears to increase with decreasing CTT over warmer water (SSTs >~7°C), while the opposite is true over colder water. A comparison with the Northern Hemisphere (NH) storm-track regions suggests that the ubiquitous SLW with markedly smaller droplet size is a unique feature for the cold SO (occurring where SSTs <~4°C), while the presence of this cloud type is much less frequent over the NH counterparts, where the SSTs are rarely colder than about 4°C at any time of the year. This study also suggests that precipitation, which has a profound influence on cloud properties, remains poorly observed over the SO with the current spaceborne sensors. Large uncertainties in precipitation properties are associated with the ubiquitous boundary layer clouds within the lowest kilometer of the atmosphere. © 2016 American Meteorological Society."
"23991212200;57200926820;","Response of the superparameterized Madden-Julian oscillation to extreme climate and basic-state variation challenges a moisture mode view",2016,"10.1175/JCLI-D-15-0790.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977558915&doi=10.1175%2fJCLI-D-15-0790.1&partnerID=40&md5=3ae029591fe321d8bb36082908d43720","The climate sensitivity of the Madden-Julian oscillation (MJO) is measured across a broad range of temperatures (1°-35°C) using a convection-permitting global climate model with homogenous sea surface temperatures. An MJO-like signal is found to be resilient in all simulations. These results are used to investigate two ideas related to the modern ""moisture mode"" view of MJO dynamics. The first hypothesis is that the MJO has dynamics analogous to a form of radiative convective self-aggregation in which longwave energy maintenance mechanisms shut down for SST ≪ 25°C. Inconsistent with this hypothesis, the explicitly simulated MJO survives cooling and retains leading moist static energy (MSE) budget terms associated with longwave destabilization even at SST < 10°C. Thus, if the MJO is a form of longwave-assisted self-aggregation, it is not one that is temperature critical, as is observed in some cases of radiative-convective equilibrium (RCE) self-aggregation. The second hypothesis is that the MJO is propagated by horizontal advection of column MSE. Inconsistent with this view, the simulated MJO survives reversal of meridional moisture gradients in the basic state and a striking role for horizontal MSE advection in its propagation energy budget cannot be detected. Rather, its eastward motion is balanced by vertical MSE advection reminiscent of gravity or Kelvin wave dynamics. These findings could suggest a tight relation between the MJO and classic equatorial waves, which would tend to challenge moisture mode views of MJO dynamics that assume horizontal moisture advection as the MJO's propagator. The simulation suite provides new opportunities for testing predictions from MJO theory across a broad climate regime. © 2016 American Meteorological Society."
"36623311400;6603156461;36867775200;","Black carbon mixing state impacts on cloud microphysical properties: Effects of aerosol plume and environmental conditions",2016,"10.1002/2016JD024851","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021088554&doi=10.1002%2f2016JD024851&partnerID=40&md5=df48902d5760ecdde90f037ff15d50cf","Black carbon (BC) is usually mixed with other aerosol species within individual aerosol particles. This mixture, along with the particles’ size and morphology, determines the particles’ optical and cloud condensation nuclei properties, and hence black carbon’s climate impacts. In this study, the particle-resolved aerosol model PartMC-MOSAIC (Particle Monte Carlo-Model for Simulating Aerosol Interactions and Chemistry) was used to quantify the importance of black carbon mixing state for predicting cloud microphysical quantities. Based on a set of about 100 cloud parcel simulations a process-level analysis framework was developed to attribute the response in cloud microphysical properties to changes in the underlying aerosol population (“plume effect”) and the cloud parcel cooling rate (“parcel effect”). In most of the simulations the plume and parcel effects had opposite signs, with the plume effect dominating. The response of cloud droplet number concentration to changes in BC emissions depended on the BC mixing state. When the aerosol population contained mainly aged BC, an increase in BC emission increased cloud droplet number concentrations (“additive effect”). In contrast, when the aerosol population contained mainly fresh BC particles, they act as sinks for condensable gaseous species, resulting in decreasing cloud droplet number concentration as BC emissions were increased (“competition effect”). Additionally, we quantified the error in cloud microphysical quantities when neglecting the information on BC mixing state. The errors ranged from -12% to +45% for the cloud droplet number fraction, from 0% to +1022% for the nucleation-scavenged BC mass fraction, from -12% to +4% for the effective radius, and from -30% to +60% for the relative dispersion. © 2016. American Geophysical Union. All Rights Reserved."
"55720018700;7202252296;55732558900;55317190600;57190122235;7102577095;54903097700;7005265210;55796430300;7003666669;55796504300;55544607500;55688930000;55317177900;7006705919;","Impacts of ENSO events on cloud radiative effects in preindustrial conditions: Changes in cloud fraction and their dependence on interactive aerosol emissions and concentrations",2016,"10.1002/2015JD024503","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977486742&doi=10.1002%2f2015JD024503&partnerID=40&md5=69c8ead58d2a3e433862a7afa4749fb4","We use three 150 year preindustrial simulations of the Community Earth System Model to quantify the impacts of El Niño-Southern Oscillation (ENSO) events on shortwave and longwave cloud radiative effects (CRESW and CRELW). Compared to recent observations from the Clouds and the Earth’s Radiant Energy System data set, the model simulation successfully reproduces larger variations of CRESW and CRELW over the tropics. The ENSO cycle is found to dominate interannual variations of cloud radiative effects. Simulated cooling (warming) effects from CRESW (CRELW) are strongest over the tropical western and central Pacific Ocean during warm ENSO events, with the largest difference between 20 and 60Wm-2, with weaker effects of 10-40Wm-2 over Indonesian regions and the subtropical Pacific Ocean. Sensitivity tests show that variations of cloud radiative effects are mainly driven by ENSO-related changes in cloud fraction. The variations in midlevel and high cloud fractions each account for approximately 20-50% of the interannual variations of CRESW over the tropics and almost all of the variations of CRELW between 60°S and 60°N. The variation of low cloud fraction contributes to most of the variations of CRESW over the midlatitude oceans. Variations in natural aerosol concentrations explained 10-30% of the variations of both CRESW and CRELW over the tropical Pacific, Indonesian regions, and the tropical Indian Ocean. Changes in natural aerosol emissions and concentrations enhance 3-5% and 1-3% of the variations of cloud radiative effects averaged over the tropics. © 2016. American Geophysical Union. All Rights Reserved."
"39760922500;54384916300;7003460432;24329221600;57188733057;8306416700;","Trends of mean and extreme temperature indices since 1874 at low-elevation sites in the southern Alps",2016,"10.1002/2015JD024582","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962645455&doi=10.1002%2f2015JD024582&partnerID=40&md5=02e6cf3004aceda86905afc0c317076e","We describe the recovery of three daily meteorological records for the southern Alps (Domodossola, Riva del Garda, and Rovereto), all starting in the second half of the nineteenth century. We use these new data, along with additional records, to study regional changes in the mean temperature and extreme indices of heat waves and cold spells frequency and duration over the period 1874-2015. The records are homogenized using subdaily cloud cover observations as a constraint for the statistical model, an approach that has never been applied before in the literature. A case study based on a record of parallel observations between a traditional meteorological window and a modern screen shows that the use of cloud cover can reduce the root-mean-square error of the homogenization by up to 30% in comparison to an unaided statistical correction.We find that mean temperature in the southern Alps has increased by 1.4°C per century over the analyzed period, with larger increases in daily minimum temperatures than maximum temperatures. The number of hot days in summer has more than tripled, and a similar increase is observed in duration of heat waves. Cold days in winter have dropped at a similar rate. These trends are mainly caused by climate change over the last few decades. © 2016. American Geophysical Union. All Rights Reserved."
"16242347100;55339298600;57192877801;6506751811;55932031800;6701527592;","Evaluation of the MiKlip decadal prediction system using satellite based cloud products",2016,"10.1127/metz/2015/0602","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85008517796&doi=10.1127%2fmetz%2f2015%2f0602&partnerID=40&md5=a76ff58e9f7686c551218c8d55007037","The decadal hindcast simulations performed for the Mittelfristige Klimaprognosen (MiKlip) project are evaluated using satellite-retrieved cloud parameters from the CM SAF cLoud, Albedo and RAdiation dataset from AVHRR data (CLARA-A1) provided by the EUMETSAT Satellite Application Facility on Climate Monitoring (CM SAF) and from the International Satellite Cloud Climatology Project (ISCCP). The forecast quality of two sets of hindcasts, Baseline-1-LR and Baseline-0, which use differing initialisations, is assessed. Basic evaluation focuses on multi-year ensemble mean fields and cloud-type histograms utilizing satellite simulator output. Additionally, ensemble evaluation employing analysis of variance (ANOVA), analysis rank histograms (ARH) and a deterministic correlation score is performed. Satellite simulator output is available for a subset of the full hindcast ensembles only. Therefore, the raw model cloud cover is complementary used. The new Baseline-1-LR hindcasts are closer to satellite data with respect to the simulated tropical/subtropical mean cloud cover pattern than the reference hindcasts (Baseline-0) emphasizing improvements of the new MiKlip initialisation procedure. A slightly overestimated occurrence rate of optically thick cloud-types is analysed for different experiments including hindcasts and simulations using realistic sea surface boundaries according to the Atmospheric Model Intercomparison Project (AMIP). By contrast, the evaluation of cirrus and cirrostratus clouds is complicated by observational based uncertainties. Time series of the 3-year mean total cloud cover averaged over the tropical warm pool (TWP) region show some correlation with the CLARA-A1 cloud fractional cover. Moreover, ensemble evaluation of the Baseline-1-LR hindcasts reveals potential predictability of the 2-5 lead year averaged total cloud cover for a large part of this region when regarding the full observational period. However, the hindcasts show only moderate positive correlations with the CLARA-A1 satellite retrieval for the TWP region which are hardly statistical significant. Evidence for predictability of the 2-5 lead year averaged total cloud cover is found for parts of the equatorial to midlatitudinal North Atlantic. © 2016 The authors."
"26643250500;","The importance of contrail ice formation formitigating the climate impact of aviation",2016,"10.1002/2015JD024696","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962871220&doi=10.1002%2f2015JD024696&partnerID=40&md5=ba7c94c1470eb75ef5ef3d3426d47386","Aircraft contrails and the cirrus clouds arising from them contribute substantially to aviation-induced climate forcing. The share of aviation in anthropogenic climate change can be reduced by avoiding contrail cirrus formation. The mitigation potential of altering the contrail formation stage is explored using a microphysical model to show how reductions in soot particle number emissions from jet engines, reductions in mean soot particle size, and a decrease in the supersaturation of aircraft exhaust plumes substantially lowers the optical depth of young contrails thereby decreasing the occurrence, lifetime, and radiative impact of contrail cirrus. The improved scientific understanding of initial ice formation processes allows atmospheric effects of mitigation options related to contrail cirrus to be investigated in unprecedented detail, especially those associated with the use of alternative aviation fuels. This study will enable a leap forward toward more reliable simulations addressing global climatic effects of contrail-induced cloudiness. © 2016. American Geophysical Union. All Rights Reserved."
"56829579700;55740664200;","The seasonal cycle of the radiation budget and cloud radiative effect in the amazon rain forest of Brazil",2016,"10.1175/JCLI-D-16-0089.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995484532&doi=10.1175%2fJCLI-D-16-0089.1&partnerID=40&md5=4ecc935a8b579980e246499e127aaad5","Changes in the climate system of the Amazon rain forest of Brazil can impact factors that influence the radiation budget such as clouds, atmospheric moisture, and the surface albedo. This study examines the relationships between clouds and radiation in this region using surface observations from the first year of the deployment of the Atmospheric Radiation Measurement (ARM) Program's Mobile Facility 1 (AMF1) in Manacapuru, Brazil, and satellite measurements from the Clouds and the Earth's Radiant Energy System (CERES). The seasonal cycles of the radiation budget and cloud radiative effects (CREs) are evaluated at the top of the atmosphere (TOA), at the surface, and within the atmospheric column using these observations and are placed into a regional context using the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). Water vapor and clouds are abundant throughout the year, even though slight decreases are observed in the dry season. The column water vapor load is large enough that the longwave radiative flux divergence is nearly constant throughout the year. Clouds produce a significant shortwave CRE at the surface and TOA, exceeding 200 W m-2 during the wet season. Discrepancies, especially in column shortwave radiative absorption, between the observations and MERRA-2 are demonstrated that warrant additional analysis of the microphysical and macrophysical cloud properties in MERRA-2. More trustworthy fields in the MERRA-2 product suggest that the expansive nearby river system impacts the regional radiation budget and thereby renders AMF1 observations potentially biased relative to regions farther removed from rivers within the Amazon rain forest. © 2016 American Meteorological Society."
"8083646600;6601999180;","Antarctic and Southern Ocean surface temperatures in CMIP5 models in the context of the surface energy budget",2016,"10.1175/JCLI-D-15-0429.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960867098&doi=10.1175%2fJCLI-D-15-0429.1&partnerID=40&md5=87625bca30248d6a1ddc13fa653b7c14","This study examines the biases, intermodel spread, and intermodel range of surface air temperature (SAT) across the Antarctic ice sheet and Southern Ocean in 26 structurally different climate models. Over the ocean (40°-60°S), an ensemble-mean warm bias peaks in late austral summer concurrently with the peak in the intermodel range of SAT. This warm bias lags a spring-summer positive bias in net surface radiation due to weak shortwave cloud forcing and is gradually reduced during autumn and winter. For the ice sheet, inconsistencies among reanalyses and observational datasets give low confidence in the ensemble-mean bias of SAT, but a small summer warm bias is suggested in comparison with nonreanalysis SAT data. The ensemble mean hides a large intermodel range of SAT, which peaks during the summer insolation maximum. In summer on the ice sheet, the SAT intermodel spread is largely associated with the surface albedo. In winter, models universally exhibit a too-strong deficit in net surface radiation related to the downward longwave radiation, implying that the lower atmosphere is too stable. This radiation deficit is balanced by the transfer of sensible heat toward the surface (which largely explains the intermodel spread in SAT) and by a subsurface heat flux. The winter bias in downward longwave radiation is due to the longwave cloud radiative effect, which the ensemble mean underestimates by a factor of 2. The implications of these results for improving climate simulations over Antarctica and the Southern Ocean are discussed. © 2016 American Meteorological Society."
"56379892200;56284543100;","Reassessing properties and radiative forcing of contrail cirrus using a climate model",2016,"10.1002/2016JD025112","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983490006&doi=10.1002%2f2016JD025112&partnerID=40&md5=ec08fa45f64172771c3e9701920b4971","Contrail cirrus is the largest known component contributing to the radiative forcing associated with aviation. Despite major advances simulating contrail cirrus, their microphysical and optical properties and the associated radiative forcing remain largely uncertain. We use a contrail cirrus parameterization in a global climate model which was extended to include a microphysical two-moment scheme. This allows a more realistic representation of microphysical processes, such as deposition and sedimentation, and therefore of the microphysical and optical properties of contrail cirrus. The simulated contrail microphysical and optical properties agree well with in situ and satellite observations. As compared to estimates using an older version of the contrail cirrus scheme, the optical depth of contrail cirrus is significantly higher, particularly in regions with high air traffic density, due to high ice crystal number concentrations on the main flight routes. Nevertheless, the estimated radiative forcing for the year 2002 supports our earlier results. The global radiative forcing of contrail cirrus for the year 2006 is estimated to be 56mW/m2. A large uncertainty of the radiative forcing estimate appears to be connected with the, on average, very small ice crystal radii simulated in the main air traffic areas, which make the application of a radiative transfer parameterization based on geometric optics questionable. © 2016. American Geophysical Union. All Rights Reserved."
"56447586200;55745955800;","Cumulus over the Tibetan Plateau in the summer based on CloudSat-CALIPSO data",2016,"10.1175/JCLI-D-15-0492.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957824188&doi=10.1175%2fJCLI-D-15-0492.1&partnerID=40&md5=a70c704ebc7d6c6a87151bca1f22a749","Cumulus (Cu) can transport heat and water vapor from the boundary layer to the free atmosphere, leading to the redistribution of heat and moist energy in the lower atmosphere. This paper uses the fine-resolution CloudSat-CALIPSO product to characterize Cu over the Tibetan Plateau (TP). It is found that Cu is one of the dominant cloud types over the TP in the northern summer. The Cu event frequency, defined as Cu occurring within 50-km segments, is 54% over the TP in the summer, which is much larger over the TP than in its surrounding regions. The surface wind vector converging at the central TP and the topographic forcing provide the necessary moisture and dynamical lifting of convection over the TP. The structure of the atmospheric moist static energy shows that the thermodynamical environment over the northern TP can be characterized as having weak instability, a shallow layer of instability, and lower altitudes for the level of free convection. The diurnal variation of Cu with frequency peaks during the daytime confirms the surface thermodynamic control on Cu formation over the TP. This study offers insights into how surface heat is transported to the free troposphere over the TP and provides an observational test of climate models in simulating shallow convection over the TP. © 2016 American Meteorological Society."
"55569698000;57203049177;39262607000;56700471900;15071907100;","Multiannual ocean-atmosphere adjustments to radiative forcing",2016,"10.1175/JCLI-D-16-0312.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992429656&doi=10.1175%2fJCLI-D-16-0312.1&partnerID=40&md5=181df95c60b2c7b5919464878ab1f699","In radiative forcing and climate feedback frameworks, the initial stratospheric and tropospheric adjustments to a forcing agent can be treated as part of the forcing and not as a feedback, as long as the average global surface temperature response is negligible. Here, a very large initial condition ensemble of the Community Earth System Model is used to analyze how the ocean shapes the fast response to radiative forcing. It is shown that not only the stratosphere and troposphere but also the ocean adjusts. This oceanic adjustment includes meridional ocean heat transport convergence anomalies, which are locally as large as the surface heat flux anomalies, and an increase of the Atlantic meridional overturning circulation. These oceanic adjustments set the lower boundary condition for the atmospheric response of the first few years, in particular, the shortwave cloud radiative effect. This cloud adjustment causes a nonlinear relationship between global energy imbalance and temperature. It proceeds with a characteristic time scale of a few years in response to the forcing rather than scaling nonlinearly with global mean temperature anomaly. It is proposed that even very short time scales are treated as a fully coupled problem and encourage other modeling groups to investigate whether our description also suits their models' behavior. A definition of the forcing term (""virtual forcing"") including oceanic adjustment processes is introduced and serves as an interpretive idea for longer time scales. © 2016 American Meteorological Society."
"55967435100;35209683700;","Impact of environmental aerosols on a developing extratropical cyclone in the superparameterized Community Atmosphere Model",2016,"10.1175/JCLI-D-16-0157.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992450813&doi=10.1175%2fJCLI-D-16-0157.1&partnerID=40&md5=cd5c4fef13c3a4ae2d080d82c2af4a3a","The impacts of environmental aerosols on the growth of an extratropical cyclone in a realistic winter flow setting are investigated using the superparameterized Community Atmosphere Model (SP-CAM) where cloud-scale dynamics and thermodynamics are explicitly resolved. An examination of the results from 13 ensemble pairs suggests that the growth rate of the cyclone is temporarily reduced as a result of increased aerosol concentrations. A convection-advection-moisture self-adjustment (CAMS) mechanism of aerosol-cyclone interaction is proposed to explain this finding. Specifically, the weakened growth is unambiguously attributed to the weakening of the cold advection underneath the midtropospheric trough of the cyclone. The weakened cold advection is in turn driven by a decrease of the zonal temperature gradient that is tied to the reduced latent heating in the stratiform cloud region of the cyclone. Invigoration of convection ahead of the cold front by aerosols is found to be directly responsible for a suppressed moisture supply into the stratiform cloud region and thus the reduced latent heating there. The regional climate implications of these results are discussed. Also highlighted is the importance of incorporating aerosol microphysical effects on deep convection in any modeling effort that aims to understand aerosol-circulation interaction at the extratropics. © 2016 American Meteorological Society."
"8972513400;57203004065;55924208000;","Calibrating climate change time-slice projections with estimates of seasonal forecast reliability",2016,"10.1175/JCLI-D-15-0087.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015263329&doi=10.1175%2fJCLI-D-15-0087.1&partnerID=40&md5=5638abc0c58f6a83b46723f56fdcea25","In earlier work, it was proposed that the reliability of climate change projections, particularly of regional rainfall, could be improved if such projections were calibrated using quantitative measures of reliability obtained by running the same model in seasonal forecast mode. This proposal is tested for fast atmospheric processes (such as clouds and convection) by considering output from versions of the same atmospheric general circulation model run at two different resolutions and forced with prescribed sea surface temperatures and sea ice. Here output from the high-resolution version of the model is treated as a proxy for truth. The reason for using this approach is simply that the twenty-first-century climate change signal is not yet known and, hence, no climate change projections can be verified using observations. Quantitative assessments of reliability of the low-resolution model, run in seasonal hindcast mode, are used to calibrate climate change time-slice projections made with the same low-resolution model. Results show that the calibrated climate change probabilities are closer to the proxy truth than the uncalibrated probabilities. Given that seasonal forecasts are performed operationally already at several centers around the world, in a seamless forecast system they provide a resource that can be used without cost to help calibrate climate change projections and make them more reliable for users. © 2016 American Meteorological Society."
"57094131800;26323066900;","Representing the Australian heat low in a GCM using different surface and cloud schemes",2016,"10.1155/2016/9702607","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956949234&doi=10.1155%2f2016%2f9702607&partnerID=40&md5=56dc7a77c1f289b7a900a9e1e34af006","The high insolation during the Southern Hemisphere summer leads to the development of a heat low over north-west Australia, which is a significant feature of the monsoon circulation. It is therefore important that General Circulation Models (GCMs) are able to represent this feature well in order to adequately represent the Australian Monsoon. Given that there are many different configurations of GCMs used globally (such as those used as part of the Coupled Model Intercomparison Project), it is difficult to assess the underlying causes of the differences in circulation between such GCMs. In order to address this problem, the work presented here makes use of three different configurations of the Australian Community Climate and Earth System Simulator (ACCESS). The configurations incorporate changes to the surface parameterization, cloud parameterization, and both together (surface and cloud) while keeping all other parameterized processes unchanged. The work finds that the surface scheme has a larger impact on the heat low than the cloud scheme, which is caused by differences in the soil thermal inertia. This study also finds that the differences in the circulation caused by changing the cloud and surface schemes together are the linear sum of the individual perturbations (i.e., no nonlinear interaction). © 2016 Matthew M. Allcock and Duncan Ackerley."
"56892889800;7501757094;","Aerosol-stratocumulus-radiation interactions over the southeast pacific: Implications to the underlying air-sea coupling",2016,"10.1175/JAS-D-15-0277.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977561264&doi=10.1175%2fJAS-D-15-0277.1&partnerID=40&md5=62a6c2fa5af54644a763bd2a0977fdd2","Recently, Chen et al. used a combination of observations and WRF simulations to illustrate that the anthropogenic aerosol-cloud microphysics-radiation interactions over the southeast Pacific can potentially reduce the excessive shortwave radiation reaching the sea surface, a common bias identified in CMIP5 models. Here, with the aid of a mixed-layer ocean, the authors further study the implications of the shortwave radiation reduction to the underlying air-sea coupling, focusing on the SST sensitivity to the changes. Results show that responses of the air-sea coupling include two negative feedbacks (a large decrease in the latent heat flux and a small decrease in the sensible heat flux, both associated with the surface cooling) and a positive feedback (an increase in the cloud cover, caused by the increase in the relative humidity within the boundary layer, especially during the daytime). The 0.1°C (Wm-22)-1 SST sensitivity is about half that documented in CMIP5 models. In addition, an effective daytime cloud fraction weighted with the solar diurnal cycle is proposed to facilitate diagnosing the intensity of cloud-radiation interactions in general circulation models. © 2016 American Meteorological Society."
"56439201600;24765842200;6701636816;25927718600;34567650200;","Response of lightning NOx emissions and ozone production to climate change: Insights from the Atmospheric Chemistry and Climate Model Intercomparison Project",2016,"10.1002/2016GL068825","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973322858&doi=10.1002%2f2016GL068825&partnerID=40&md5=3fd870471b028f90e3d792a76cb08181","Results from an ensemble of models are used to investigate the response of lightning nitrogen oxide emissions to climate change and the consequent impacts on ozone production. Most models generate lightning using a parameterization based on cloud top height. With this approach and a present-day global emission of 5 TgN, we estimate a linear response with respect to changes in global surface temperature of +0.44 ± 0.05 TgN K−1. However, two models using alternative approaches give +0.14 and −0.55 TgN K−1 suggesting that the simulated response is highly dependent on lightning parameterization. Lightning NOx is found to have an ozone production efficiency of 6.5 ± 4.7 times that of surface NOx sources. This wide range of efficiencies across models is partly due to the assumed vertical distribution of the lightning source and partly to the treatment of nonmethane volatile organic compound (NMVOC) chemistry. Careful consideration of the vertical distribution of emissions is needed, given its large influence on ozone production. ©2016. The Authors."
"36495559200;35551120200;","Comparison of climate preferences for domestic and international beach holidays: A case study of Canadian travelers",2016,"10.3390/atmos7020030","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960130656&doi=10.3390%2fatmos7020030&partnerID=40&md5=5a966e9a8d8e14ecfd0a1fab32a868a9","Coastal tourism is the largest segment of global leisure tourism and it is firmly linked to the destination's natural resources-with climatic resources chief among them. Through observations and survey responses of beach users, studies have evaluated climatic resources for coastal tourism by quantifying optimal and unacceptable conditions. However, these studies have not taken into consideration that different forms of holidays (e.g., daytrips, short trips, main annual holiday, ""once-in-a-lifetime"" trip) may have varying degrees of resilience to climatic conditions. This is the first study to explore whether ideal and unacceptable climatic conditions vary between domestic and international tourists. Using an in situ survey, Canadian beach users traveling domestically (n = 359) and internationally (n = 120) were examined. Key findings include statistically significant differences (p ≤ 0.05) between the two sample groups for every climate variable, with the international sample more resilient to a broader range of weather conditions, including a greater acceptance for warm temperatures, longer rainfall durations, higher wind speeds, and greater cloud cover. This study adds further insight into the complexities of evaluating climate for tourism, with implications for the demand response of tourists to climate change. © 2016 by the authors."
"57188817814;7003875148;24472110700;24070152900;7201572145;7005753600;57192204111;34771905600;55890446800;57192212804;57192207346;7201507866;","Atmospheric conditions during the arctic clouds in summer experiment (ACSE): Contrasting open water and sea ice surfaces during melt and freeze-up seasons",2016,"10.1175/JCLI-D-16-0211.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85000936653&doi=10.1175%2fJCLI-D-16-0211.1&partnerID=40&md5=a73146985f144e535d9af5d5d6f0db90","The Arctic Clouds in Summer Experiment (ACSE) was conducted during summer and early autumn 2014, providing a detailed view of the seasonal transition from ice melt into freeze-up. Measurements were taken over both ice-free and ice-covered surfaces near the ice edge, offering insight into the role of the surface state in shaping the atmospheric conditions. The initiation of the autumn freeze-up was related to a change in air mass, rather than to changes in solar radiation alone; the lower atmosphere cooled abruptly, leading to a surface heat loss. During melt season, strong surface inversions persisted over the ice, while elevated inversions were more frequent over open water. These differences disappeared during autumn freeze-up, when elevated inversions persisted over both ice-free and ice-covered conditions. These results are in contrast to previous studies that found a well-mixed boundary layer persisting in summer and an increased frequency of surface-based inversions in autumn, suggesting that knowledge derived from measurements taken within the pan-Arctic area and on the central ice pack does not necessarily apply closer to the ice edge. This study offers an insight into the atmospheric processes that occur during a crucial period of the year; understanding and accurately modeling these processes is essential for the improvement of ice-extent predictions and future Arctic climate projections. © 2016 American Meteorological Society."
"56162279000;21234333100;7407002527;8872529400;55947319900;6701410484;7501466543;","Persistent longitudinal variations in 8years of CIPS/AIM polar mesospheric clouds",2016,"10.1002/2015JD024624","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979554372&doi=10.1002%2f2015JD024624&partnerID=40&md5=5dbb2246d6205bbc2f35d4b1a89cd815","The Cloud Imaging and Particle Size (CIPS) instrument on the Aeronomy of Ice in the Mesosphere (AIM) satellite provides an opportunity to study the longitudinal variation in polar mesospheric cloud (PMC). We examined the longitudinal variation in PMC albedo using 8 years (2007-2014) of observations from the CIPS instrument. The results show that the PMC albedo in the Southern Hemisphere (SH), especially in the latitude band of 80°S-85°S, is persistently low (~65% relative to the rest of the hemisphere) within 60°W to 150°W longitude. In the Northern Hemisphere (NH), however, PMC albedo is found to be relatively zonally asymmetry. Harmonic analyses show that the persistent longitudinal variation in the SH PMC albedo is due to zonal wave numbers 1 through 4 (WN1-WN4) processes with minima in the longitude range of 60°W-150°W. The influence of temperature and H2O on the longitudinal variation of the PMC albedo is discussed based on results obtained using a simple 0-D PMC model and temperature from the Microwave Limb Sounder (MLS) and the Sounding of the Atmosphere with Broadband Emission Radiometry (SABER) and H2O from MLS. The modeled region of low ice mass in the SH is generally consistent with that of low PMC albedo seen in CIPS. Tidal analyses using the SABER temperatures indicate that the nonmigrating semidiurnal tides with modes of S0, W1, and E1 might be the main drivers of the persistent longitudinal variations of PMC albedo in the SH. Nonmigrating tides aremuch weaker in the NH and consistent with the observed lack of longitudinal variability in PMC albedo. © 2016. American Geophysical Union. All Rights Reserved."
"56587124900;36538539800;55624488227;7202010686;","Application of online-coupled WRF/Chem-MADRID in East Asia: Model evaluation and climatic effects of anthropogenic aerosols",2016,"10.1016/j.atmosenv.2015.03.052","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949624899&doi=10.1016%2fj.atmosenv.2015.03.052&partnerID=40&md5=af65825aa08ead1f7971dceb85e99542","The online-coupled Weather Research and Forecasting model with Chemistry with the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (referred to as WRF/Chem-MADRID) is applied to simulate meteorological fields, air quality, and the direct and indirect effects of anthropogenic aerosols over East Asia in four months (January, April, July, and October) in 2008. Model evaluation against available surface and satellite measurements shows that despite some model biases, WRF/Chem-MADRID is able to reproduce reasonably well the spatial and seasonal variations of most meteorological fields and chemical concentrations. Large model biases for chemical concentrations are attributed to uncertainties in emissions and their spatial and vertical allocations, simulated meteorological fields, imperfectness of model representations of aerosol formation processes, uncertainties in the observations based on air pollution index, and the use of a coarse grid resolution. The results show that anthropogenic aerosols can reduce net shortwave flux at the surface by up to 40.5-57.2 W m-2, Temperature at 2-m by up to 0.5-0.8 °C, NO2 photolytic rates by up to 0.06-0.1 min-1 and the planetary boundary layer height by up to 83.6-130.4 m. Anthropogenic aerosols contribute to the number concentrations of aerosols by up to 6.2-8.6 × 104 cm-3 and the surface cloud concentration nuclei at a supersaturation of 0.5% by up to 1.0-1.6 × 104 cm-3. They increase the column cloud droplet number concentrations by up to 3.6-11.7 × 108 cm-2 and cloud optical thickness by up to 19.8-33.2. However, anthropogenic aerosols decrease daily precipitation in most areas by up to 3.9-18.6 mm during the 4 months. These results indicate the importance of anthropogenic aerosols in modulating regional climate changes in East Asia through aerosol direct and indirect effects, as well as the need to further improve the performance of online-coupled models. © 2015 Elsevier Ltd."
"6701382162;7102084129;6602777467;","Evaluation of geostationary satellite observations and the development of a 1-2h prediction model for future storm intensity",2016,"10.1002/2016JD024768","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977590091&doi=10.1002%2f2016JD024768&partnerID=40&md5=0138c29e6ce835cf36f81fb110c7026e","A study was conducted to gain insights into the use of geostationary satellite-based indicators for characterizing and identifying growing cumulus clouds that evolve into severe weather producing convective storms. Eleven convective initiation (CI), 41 cloud top temperature-effective radius (T-re), and 9 additional fields were formed for 340 growing cumulus clouds that were manually tracked for 2 h and checked for association with severe weather to 2-3 h into the future. The geostationary satellite data were at 5 min resolution from Meteosat-8 on six convectively active days in 2010, 2012, and 2013. The study’s goals were to determine which satellite fields are useful to forecasting severe storms and to form a simple model for predicting future storm intensity. The CI fields were applied on 3 × 3 pixel regions, and the T-re fields were analyzed on 9 × 9 and 51 × 51 pixel domains (needed when forming T-re vertical profiles). Of the 340 growing cumulus clouds examined, 34 were later associated with severe weather (using European Severe Weather Database reports), with the remaining being nonsevere storms. Using a multivariate analysis, transforming predictors into their empirical posterior probability, and maximizing the Peirce skill score, the best predictors were T1451 (51 × 51 pixel T, where re exceeds 14 µm), TG9 (9× 9 pixel glaciation T surrounding a growing cloud), and ReBRTG51 (51 × 51 pixel re at the breakpoint T in the T-re profile). Rapid cloud growth prior to severe storm formation leads to delayed particle growth, colder temperatures of the first 14 µmparticles, and lower TG values. © 2016. American Geophysical Union. All Rights Reserved."
"16027966800;7402332362;34770976500;6701410484;7202607288;","Impact of the January 2012 solar proton event on polar mesospheric clouds",2016,"10.1002/2016JD024820","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981343952&doi=10.1002%2f2016JD024820&partnerID=40&md5=9e0d3368d17f3226d13d0c9947254e95","We use data from the Aeronomy of Ice in the Mesosphere mission and simulations using the Whole Atmosphere Community Climate Model to determine the impact of the 23-30 January 2012 solar proton event (SPE) on polar mesospheric clouds (PMCs) and mesospheric water vapor. We see a small heating and loss of ice mass on 26 January that is consistent with prior results but is not statistically significant. We also find a previously unreported but statistically significant ~10% increase in ice mass and in water vapor in the sublimation area in the model that occurs in the 7 to 14 days following the start of the event. The magnitude of the response to the January 2012 SPE is small compared to other sources of variability like gravity waves and planetary waves; however, sensitivity tests suggest that with larger SPEs this delayed increase in ice mass will increase, while there is little change in the loss of ice mass early in the event. The PMC response to SPEs in models is dependent on the gravity wave parameterization, and temperature anomalies from SPEs may be useful in evaluating and tuning gravity wave parameterizations. © 2016. American Geophysical Union. All Rights Reserved."
"8279747600;7004817795;55976646100;","GOES-derived fog and low cloud indices for coastal north and central California ecological analyses",2016,"10.1002/2015EA000119","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037732712&doi=10.1002%2f2015EA000119&partnerID=40&md5=2b825ab6614fefe84e0571ce5ce31d6d","Fog and low cloud cover (FLCC) strongly influences the water, energy, and nutrient flux of coastal ecosystems. Easy-to-use FLCC data are needed to quantify the impacts of FLCC on ecosystem dynamics especially during hot and dry Mediterranean climate summers. Monthly, annual, and decadal FLCC digital maps (indices) were derived for June–September 1999–2009 for coastal California, latitude 34.50°N (south of Monterey Bay) to latitude 41.95°N (north of Crescent City) from 26,000 hourly night and day Geostationary Operational Environmental Satellite (GOES) images. Monthly average FLCC ranges from <2 to 18 hours per day (h/d). Average FLCC over the ocean increases from north (9 h/d) to south (14 h/d), whereas on land, FLCC is highest where land juts into the prevailing NW winds and is lowest in the lee of major capes. FLCC advects farthest inland through low-lying NW ocean-facing valleys. At night, average total hours of FLCC are higher more frequently on land than over the ocean. The interannual FLCC coefficient of variation shows long-term geographic stability that is strongly associated with landform position. FLCC hours per day mapped contours, derived from decadal average FLCC, delineate the commonly used term “fog belt” into FLCC zones with increased locational precision. FLCC indices are available for download from the California Landscape Conservation Cooperative Climate Commons website (http://climate.calcommons.org/datasets/summertime-fog). FLCC indices can improve analyses of biogeographic and bioclimatic species distribution models; understanding meteorological mechanisms driving FLCC patterns; solar energy feasibility studies; investigations of ecohydrology, evapotranspiration, and agricultural irrigation demand; and viticulture ripening models. ©2015. The Authors."
"55667257200;57190859215;7004508767;","Dynamic feedback of aerosol effects on the East Asian summer monsoon",2016,"10.1175/JCLI-D-15-0758.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983472868&doi=10.1175%2fJCLI-D-15-0758.1&partnerID=40&md5=d1d9d682919def81820539861495e37c","The influence of present-day anthropogenic aerosols on the summer monsoon over the East Asia region was simulated using the Community Earth System Model coupled with a slab ocean model. The simulations revealed significant radiative forcing from anthropogenic aerosols and associated changes in clouds over East Asia and the northwestern Pacific; however, their spatial patterns differed from the exhibited surface temperature and precipitation responses. Two major dynamic feedback mechanisms were identified to explain such discrepancies. The wind-evaporation-sea surface temperature (WES) feedback, triggered by an initial cooling over the midlatitude sea surface, induced an equatorward expansion of ocean cooling through strengthened trade winds. The sea surface cooling excited a meridional wave pattern similar to the Pacific- Japan teleconnection pattern. Although the aerosol effect generally caused weakening in summer monsoon strength and regional precipitation over East Asia, precipitation increases were seen over the locations of the midlatitude mei-yu front and around the tropics. These precipitation increases are primarily associated with the WES feedback and teleconnection patterns. The aerosol effect also reached the upper troposphere, causing an equatorward shift of the jet stream over East Asia and the northwestern Pacific, indicating a much broader scale of teleconnection."
"8308614300;8287337100;35453194100;57214063113;7201888941;","The Intermediate Complexity Atmospheric Research model (ICAR)",2016,"10.1175/JHM-D-15-0155.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961393460&doi=10.1175%2fJHM-D-15-0155.1&partnerID=40&md5=50947bbbba2dea6c30964427cf7d3642","With limited computational resources, there is a need for computationally frugal models. This is particularly the case for atmospheric sciences, which have long relied on either simplistic analytical solutions or computationally expensive numerical models. The simpler solutions are inadequate for many problems, while the cost of numerical models makes their use impossible for many problems, most notably high-resolution climate downscaling applications spanning large areas, long time periods, and many global climate projections. Here the Intermediate Complexity Atmospheric Research model (ICAR) is presented to provide a new step along the modeling complexity continuum. ICAR leverages an analytical solution for high-resolution perturbations to wind velocities, in conjunction with numerical physics schemes, that is, advection and cloud microphysics, to simulate the atmosphere. The focus of the initial development of ICAR is for predictions of precipitation, and eventually temperature, humidity, and radiation at the land surface. Comparisons between ICAR and the Weather Research and Forecasting (WRF) Model for simulations over an idealized mountain are presented, as well as among ICAR, WRF, and the Parameter-Elevation Regressions on Independent Slopes Model (PRISM) observation-based product for a year-long simulation over the Colorado Rockies. In the ideal simulations, ICAR matches WRF precipitation predictions across a range of environmental conditions with a coefficient of determination r2 of 0.92. In the Colorado Rockies, ICAR, WRF, and PRISM show very good agreement, with differences between ICAR and WRF comparable to the differences between WRF and PRISM in the cool season. For these simulations, WRF required 140-800 times more computational resources than ICAR. © 2016 American Meteorological Society."
"29067574800;15724418700;","Climate model biases in the width of the tropical belt",2016,"10.1175/JCLI-D-15-0336.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960923868&doi=10.1175%2fJCLI-D-15-0336.1&partnerID=40&md5=14d3269222cdc735cf6cb5916294a986","Earth's arid subtropics are situated at the edges of the tropical belt, which encircles the planet along the equator and covers half of its surface area. The climate of the tropical belt is strongly influenced by the Hadley cells, with their subsidence and easterly trade winds both sustaining the aridity at the belt's edges. The understanding of Earth's past, present, and future climates is contingent on understanding the dynamics influencing this region. An important but unanswered question is how realistically climate models reproduce the mean state of the tropical belt. This study augments the existing literature by examining the mean width and seasonality of the tropical belt in climate models from phase 5 of CMIP (CMIP5) and experiments from the second phase of the Chemistry-Climate Model Validation (CCMVal-2) activity of the Stratospheric Processes and Their Role in Climate (SPARC) project. While the models overall reproduce the structure of the tropical belt width's seasonal cycle, they underestimate its amplitude and cannot consistently reproduce the seasonal cycle lag between the Northern Hemisphere Hadley cell edge and subtropical jet latitudes found in observations. Additionally, up to 50% of the intermodel variation in mean tropical belt width can be attributed to model horizontal resolution, with finer resolution leading to a narrower tropical belt. Finer resolution is associated with an equatorward shift and intensification of subtropical eddy momentum flux convergence, which via the Coriolis torque explains essentially all of the grid-size bias and a large fraction of the total intermodel variation in Hadley cell width. © 2016 American Meteorological Society."
"57198271544;12769875100;","A framework for evaluating climate model performance metrics",2016,"10.1175/JCLI-D-15-0114.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960917754&doi=10.1175%2fJCLI-D-15-0114.1&partnerID=40&md5=4e529cce02a5901f0f5bbebe6b1e93b8","Given the large amount of climate model output generated from the series of simulations from phase 5 of the Coupled Model Intercomparison Project (CMIP5), a standard set of performance metrics would facilitate model intercomparison and tracking performance improvements. However, no framework exists for the evaluation of performance metrics. The proposed framework systematically integrates observations into metric assessment to quantitatively evaluate metrics. An optimal metric is defined in this framework as one that measures a behavior that is strongly linked to model quality in representing mean-state present-day climate. The goal of the framework is to objectively and quantitatively evaluate the ability of a performance metric to represent overall model quality. The framework is demonstrated, and the design principles are discussed using a novel set of performance metrics, which assess the simulation of top-of-atmosphere (TOA) and surface radiative flux variance and probability distributions within 34 CMIP5 models against Clouds and the Earth's Radiant Energy System (CERES) observations and GISS Surface Temperature Analysis (GISTEMP). Of the 44 tested metrics, the optimal metrics are found to be those that evaluate global-mean TOA radiation flux variance. © 2016 American Meteorological Society."
"56000281400;7101699632;56037439800;6603025800;","Light Snow Precipitation and Effects on Weather and Climate",2016,"10.1016/bs.agph.2016.09.001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84998694408&doi=10.1016%2fbs.agph.2016.09.001&partnerID=40&md5=11963c156b1de5ba8f94161cf6bd54e1","The objective of this work is to better understand light snow (LSN) precipitation measurements (precipitation rate (PR) < 0.5 mm/h) collected by optical present weather sensors (OPWS), weighing gauges, and spectral probes that are important for meteorological and hydrometeorological applications. Observations collected during the Satellite Applications for Arctic Weather and Search andrescue (SAR) Operations (SAAWSO) project that took place over Goose Bay, Newfoundland (NFL), Canada were studied to assess LSN characteristics and instrument sensitivities. Two case studies representing extreme environmental conditions temperature between 0 and −35°C, and snow occurrence for the SAAWSO project are presented. The ice crystal size and shape of LSN using a new platform called Ground Cloud Imaging Probe (GCIP) were obtained between 7.5 and 930 μm over 60 channels at 15 μm intervals. The measurements from the GCIP, Laser Precipitation Monitor (LPM), weighing gauges, and OPWS were used in the analysis. The results suggested the following: (1) LSN occurs at about 80% of time over the Arctic regions; (2) LSN can play a significant role in cooling at the surface and dehydration of the upper levels; and (3) OPWS can respond to LSN conditions better than weighing gauges. It is concluded that OPWS and spectral probes can improve measurement of LSN, including snow particle shape and size distribution with sizes <0.5 mm. Further research on LSN impact on weather and climate simulations is needed. © 2016 Elsevier Inc."
"23976332400;12645612500;","Study of the effect of temporal sampling frequency on DSCOVR observations using the GEOS-5 Nature Run results (Part II): Cloud coverage",2016,"10.3390/rs8050431","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971447468&doi=10.3390%2frs8050431&partnerID=40&md5=03c0effcf69ac64a4d2863c606a0eaab","This is the second part of a study on how temporal sampling frequency affects satellite retrievals in support of the Deep Space Climate Observatory (DSCOVR) mission. Continuing from Part 1, which looked at Earth's radiation budget, this paper presents the effect of sampling frequency on DSCOVR-derived cloud fraction. The output from NASA's Goddard Earth Observing System version 5 (GEOS-5) Nature Run is used as the ""truth"". The effect of temporal resolution on potential DSCOVR observations is assessed by subsampling the full Nature Run data. A set of metrics, including uncertainty and absolute error in the subsampled time series, correlation between the original and the subsamples, and Fourier analysis have been used for this study. Results show that, for a given sampling frequency, the uncertainties in the annual mean cloud fraction of the sunlit half of the Earth are larger over land than over ocean. Analysis of correlation coefficients between the subsamples and the original time series demonstrates that even though sampling at certain longer time intervals may not increase the uncertainty in the mean, the subsampled time series is further and further away from the ""truth"" as the sampling interval becomes larger and larger. Fourier analysis shows that the simulated DSCOVR cloud fraction has underlying periodical features at certain time intervals, such as 8, 12, and 24 h. If the data is subsampled at these frequencies, the uncertainties in the mean cloud fraction are higher. These results provide helpful insights for the DSCOVR temporal sampling strategy. © 2016 by the authors."
"55732558900;7202252296;22953153500;","Potential sea salt aerosol sources from frost flowers in the pan-Arctic region",2016,"10.1002/2015JD024713","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988876275&doi=10.1002%2f2015JD024713&partnerID=40&md5=5ca93ec7aafcb4eafba50a2a66d36546","In order to better represent observed wintertime aerosol mass and number concentrations in the pan-Arctic (60°N–90°N) region, we implemented an observationally based parameterization for estimating sea salt production from frost flowers in the Community Earth System Model (CESM, version 1.2.1). In this work, we evaluate the potential influence of this sea salt source on the pan-Arctic climate. Results show that frost flower salt emissions increase the modeled surface sea salt aerosol mass concentration by roughly 200% at Barrow and 100% at Alert and accumulation-mode number concentration by about a factor of 2 at Barrow and more than a factor of 10 at Alert in the winter months when new sea ice and frost flowers are present. The magnitude of sea salt aerosol mass and number concentrations at the surface in Barrow during winter simulated by the model configuration that includes this parameterization agrees better with observations by 48% and 12%, respectively, than the standard CESM simulation without a frost flower salt particle source. At Alert, the simulation with this parameterization overestimates observed sea salt aerosol mass concentration by 150% during winter in contrast to the underestimation of 63% in the simulation without this frost flower source, while it produces particle number concentration about 14% closer to observation than the standard CESM simulation. However, because the CESM version used here underestimates transported sulfate in winter, the reference accumulation-mode number concentrations at Alert are also underestimated. Adding these frost flower salt particle emissions increases sea salt aerosol optical depth by 10% in the pan-Arctic region and results in a small cooling at the surface. The increase in salt aerosol mass concentrations of a factor of 8 provides nearly two times the cloud condensation nuclei concentration at supersaturation of 0.1%, as well as 10% increases in cloud droplet number and 40% increases in liquid water content near coastal regions adjacent to continents. These cloud changes reduce longwave cloud forcing at the top of the atmosphere by 3% and cause a small surface warming, increasing the downward longwave flux at the surface by 1.8 W m-2 in the pan-Arctic under the present-day climate. This regional average longwave warming due to the presence of clouds attributed to frost flower sea salts is roughly half of previous observed surface longwave fluxes and cloud-forcing estimates reported in Alaska, implying that the longwave enhancement due to frost flower salts may be comparable to those estimated for anthropogenic aerosol emissions. Since the potential frost flower area is parameterized as the maximum possible region on which frost flowers grow for the modeled atmospheric temperature and sea ice conditions and the model underestimates the number of accumulation-mode particles from midlatitude anthropogenic sources transported in winter, the calculated aerosol indirect effect of frost flower sea salts in this work can be regarded an upper bound. © 2016. American Geophysical Union. All Rights Reserved."
"37089487300;56468201900;55794021100;55771223200;57190879276;","Influence of below-cloud evaporation on deuterium excess in precipitation of arid Central Asia and its meteorological controls",2016,"10.1175/JHM-D-15-0203.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983766482&doi=10.1175%2fJHM-D-15-0203.1&partnerID=40&md5=dd70be4259183d7aab6b5782f651bfcd","The deuterium excess is a second-order parameter linking water-stable oxygen and hydrogen isotopes and has been widely used in hydrological studies. The deuterium excess in precipitation is greatly influenced by below-cloud evaporation through unsaturated air, especially in an arid climate. Based on an observation network of isotopes in precipitation of arid central Asia, the difference in deuterium excess from cloud base to ground was calculated for each sampling site. The difference on the southern slope of the Tian Shan is generally larger than that on the northern slope, and the difference during the summer months is greater than that during the winter months. Generally, an increase of 1% in evaporation of raindrops causes deuterium excess to decrease by approximately 1‰. Under conditions of low air temperature, high relative humidity, heavy precipitation, and large raindrop diameter, a good linear correlation is exhibited between evaporation proportion and difference in deuterium excess, and a linear regression slope of &lt;1‰ %-1 can be seen; in contrast, under conditions of high air temperature, low relative humidity, light precipitation, and small raindrop diameter, the linear relationship is relatively weak, and the slope is much larger than 1‰ %-1. A sensitivity analysis under different climate scenarios indicates that, if air temperature has increased by 5°C, deuterium excess difference decreases by 0.3‰-4.0‰ for each site; if relative humidity increases by 10%, deuterium excess difference increases by 1.1‰-10.3‰. © 2016 American Meteorological Society."
"7005470229;","Estimating dew yield worldwide from a few meteo data",2016,"10.1016/j.atmosres.2015.07.018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84939636205&doi=10.1016%2fj.atmosres.2015.07.018&partnerID=40&md5=b73df69df7aa3d06faee7871eddccafb","There is a general need to determine dew yield in any place of the world. However, its determination requires systematic measurements that are not available everywhere. In addition, it depends on the particularities of the dew collector. A simple analytical formula valid for planar dew collectors is elaborated here. It is based on laboratory experiments where it is established that heat loss with surrounding air is the dominant parameter that limits dew condensation. A simple analytical formulation is then derived, which only needs cloud coverage, wind velocity, air and dew point temperature data to be collected, at least once in a day before sunrise. The formulation is tested in several places in the world with different climates. Agreement within typically 30% is found with dew measurements. Such an analytical relationship can thus provide a useful tool to obtain a worldwide estimation of the dew potential. © 2015 Elsevier B.V."
"55331956500;7102495313;6506738607;55342815900;6602079010;37261023300;","Melt onset over Arctic sea ice controlled by atmospheric moisture transport",2016,"10.1002/2016GL069330","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977521594&doi=10.1002%2f2016GL069330&partnerID=40&md5=b15be0ec4e91e847542cc2316e293c44","The timing of melt onset affects the surface energy uptake throughout the melt season. Yet the processes triggering melt and causing its large interannual variability are not well understood. Here we show that melt onset over Arctic sea ice is initiated by positive anomalies of water vapor, clouds, and air temperatures that increase the downwelling longwave radiation (LWD) to the surface. The earlier melt onset occurs; the stronger are these anomalies. Downwelling shortwave radiation (SWD) is smaller than usual at melt onset, indicating that melt is not triggered by SWD. When melt occurs early, an anomalously opaque atmosphere with positive LWD anomalies preconditions the surface for weeks preceding melt. In contrast, when melt begins late, clearer than usual conditions are evident prior to melt. Hence, atmospheric processes are imperative for melt onset. It is also found that spring LWD increased during recent decades, consistent with trends toward an earlier melt onset. ©2016. American Geophysical Union. All Rights Reserved."
"56972852800;6504075898;21234333100;55947319900;7406755458;7003854810;15829150100;7005312540;7402583785;","Southern Hemisphere summer mesopause responses to El Niño-Southern Oscillation",2016,"10.1175/JCLI-D-15-0816.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983504513&doi=10.1175%2fJCLI-D-15-0816.1&partnerID=40&md5=f07a9cc80c831f2765cb49683f107c91","In the Southern Hemisphere (SH) polar region, satellite observations reveal a significant uppermesosphere cooling and a lower-thermosphere warming during warm ENSO events in December. An opposite pattern is observed in the tropical mesopause region. The observed upper-mesosphere cooling agrees with a climate model simulation. Analysis of the simulation suggests that enhanced planetary wave (PW) dissipation in the Northern Hemisphere (NH) high-latitude stratosphere during El Niño strengthens the Brewer-Dobson circulation and cools the equatorial stratosphere. This increases the magnitude of the SH stratosphere meridional temperature gradient and thus causes the anomalous stratospheric easterly zonal wind and early breakdown of the SH stratospheric polar vortex. The resulting perturbation to gravity wave (GW) filtering causes anomalous SH mesospheric eastward GW forcing and polar upwelling and cooling. In addition, constructive inference of ENSO and quasibiennial oscillation (QBO) could lead to stronger stratospheric easterly zonal wind anomalies at the SH high latitudes in November and December and early breakdown of the SH stratospheric polar vortex during warm ENSO events in the easterly QBO phase (defined by the equatorial zonal wind at ;25 hPa). This would in turn cause much more SH mesospheric eastward GW forcing and much colder polar temperatures, and hence it would induce an early onset time of SH summer polar mesospheric clouds (PMCs). The opposite mechanism occurs during cold ENSO events in the westerly QBO phase. This implies that ENSO together with QBO could significantly modulate the breakdown time of SH stratospheric polar vortex and the onset time of SH PMC."
"57212021933;6603613067;8570871900;55553811200;7005635934;55688930000;7404736154;","Seasonality of global and arctic black carbon processes in the arctic monitoring and assessment programme models",2016,"10.1002/2016JD024849","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977562794&doi=10.1002%2f2016JD024849&partnerID=40&md5=3548e84c4627686aafefa234585d76d5","This study quantifies black carbon (BC) processes in three global climate models and one chemistry transport model, with focus on the seasonality of BC transport, emissions, wet and dry deposition in the Arctic. In the models, transport of BC to the Arctic from lower latitudes is the major BC source for this region. Arctic emissions are very small. All models simulated a similar annual cycle of BC transport from lower latitudes to the Arctic, with maximum transport occurring in July. Substantial differences were found in simulated BC burdens and vertical distributions, with Canadian Atmospheric Global Climate Model (CanAM) (Norwegian Earth System Model, NorESM) producing the strongest (weakest) seasonal cycle. CanAM also has the shortest annual mean residence time for BC in the Arctic followed by Swedish Meteorological and Hydrological InstituteMultiscale Atmospheric Transport and Chemistrymodel, Community Earth SystemModel, and NorESM. Overall, considerable differences in wet deposition efficiencies in the models exist and are a leading cause of differences in simulated BC burdens. Results from model sensitivity experiments indicate that convective scavenging outside the Arctic reduces the mean altitude of BC residing in the Arctic, making it more susceptible to scavenging by stratiform (layer) clouds in the Arctic. Consequently, scavenging of BC in convective clouds outside the Arctic acts to substantially increase the overall efficiency of BC wet deposition in the Arctic, which leads to low BC burdens and a more pronounced seasonal cycle compared to simulations without convective BC scavenging. In contrast, the simulated seasonality of BC concentrations in the upper troposphere is only weakly influenced by wet deposition in stratiform clouds, whereas lower tropospheric concentrations are highly sensitive. © 2016. The Authors."
"55340272500;15757708600;6701847229;6602324100;7801317846;7004279859;7003748648;","Objective calibration of regional climate models: Application over Europe and North America",2016,"10.1175/JCLI-D-15-0302.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957837278&doi=10.1175%2fJCLI-D-15-0302.1&partnerID=40&md5=5a0d4279b0c8fab6ed04a95fe9dd753f","An important source of model uncertainty in climate models arises from unconfined model parameters in physical parameterizations. These parameters are commonly estimated on the basis of manual adjustments (expert tuning), which carries the risk of overtuning the parameters for a specific climate region or time period. This issue is particularly germane in the case of regional climate models (RCMs), which are often developed and used in one or a few geographical regions only. This study addresses the role of objective parameter calibration in this context. Using a previously developed objective calibration methodology, an RCM is calibrated over two regions (Europe and North America) and is used to investigate the transferability of the results. A total of eight different model parameters are calibrated, using a metamodel to account for parameter interactions. The study demonstrates that the calibration is effective in reducing model biases in both domains. For Europe, this concerns in particular a pronounced reduction of the summer warm bias and the associated overestimation of interannual temperature variability that have persisted through previous expert tuning efforts and are common in many global and regional climate models. The key process responsible for this improvement is an increased hydraulic conductivity. Higher hydraulic conductivity increases the water availability at the land surface and leads to increased evaporative cooling, stronger low cloud formation, and associated reduced incoming shortwave radiation. The calibrated parameter values are found to be almost identical for both domains; that is, the parameter calibration is transferable between the two regions. This is a promising result and indicates that models may be more universal than previously considered. © 2016 American Meteorological Society."
"56461663400;6701562113;8631239200;57193132723;57203474131;","Improving high-resolution weather forecasts using the Weather Research and Forecasting (WRF) model with an updated Kain-Fritsch scheme",2016,"10.1175/MWR-D-15-0005.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961392039&doi=10.1175%2fMWR-D-15-0005.1&partnerID=40&md5=8bd56f97faa16457931490b4d4e380ad","Efforts to improve the prediction accuracy of high-resolution (1-10 km) surface precipitation distribution and variability are of vital importance to local aspects of air pollution, wet deposition, and regional climate. However, precipitation biases and errors can occur at these spatial scales due to uncertainties in initial meteorological conditions and/or grid-scale cloud microphysics schemes. In particular, it is still unclear to what extent a subgrid-scale convection scheme could be modified to bring in scale awareness for improving high-resolution short-term precipitation forecasts in the WRF Model. To address these issues, the authors introduced scale-aware parameterized cloud dynamics for high-resolution forecasts by making several changes to the Kain-Fritsch (KF) convective parameterization scheme in the WRF Model. These changes include subgrid-scale cloud-radiation interactions, a dynamic adjustment time scale, impacts of cloud updraft mass fluxes on grid-scale vertical velocity, and lifting condensation level-based entrainment methodology that includes scale dependency. A series of 48-h retrospective forecasts using a combination of three treatments of convection (KF, updated KF, and the use of no cumulus parameterization), two cloud microphysics schemes, and two types of initial condition datasets were performed over the U.S. southern Great Plains on 9- and 3-km grid spacings during the summers of 2002 and 2010. Results indicate that 1) the source of initial conditions plays a key role in high-resolution precipitation forecasting, and 2) the authors' updated KF scheme greatly alleviates the excessive precipitation at 9-km grid spacing and improves results at 3-km grid spacing as well. Overall, the study found that the updated KF scheme incorporated into a high-resolution model does provide better forecasts for precipitation location and intensity. © 2016 American Meteorological Society."
"7401796996;8629713500;56768785200;7006783796;6506827279;7102651635;","A radiation closure study of Arctic stratus cloud microphysical properties using the collocated satellite-surface data and Fu-Liou radiative transfer model",2016,"10.1002/2016JD025255","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984674608&doi=10.1002%2f2016JD025255&partnerID=40&md5=546258f29dcb9d94e925cc39062fd2d8","Retrievals of cloud microphysical properties based on passive satellite imagery are especially difficult over snow-covered surfaces because of the bright and cold surface. To help quantify their uncertainties, single-layered overcast liquid-phase Arctic stratus cloud microphysical properties retrieved by using the Clouds and the Earth’s Radiant Energy System Edition 2 and Edition 4 (CERES Ed2 and Ed4) algorithms are compared with ground-based retrievals at the Atmospheric Radiation Measurement North Slope of Alaska (ARM NSA) site at Barrow, AK, during the period from March 2000 to December 2006. A total of 206 and 140 snow-free cases (Rsfc ≤ 0.3), and 108 and 106 snow cases (Rsfc&gt;0.3), respectively, were selected from Terra and Aqua satellite passes over the ARM NSA site. The CERES Ed4 and Ed2 optical depth (t) and liquid water path (LWP) retrievals from both Terra and Aqua are almost identical and have excellent agreement with ARM retrievals under snow-free and snow conditions. In order to reach a radiation closure study for both the surface and top of atmosphere (TOA) radiation budgets, the ARM precision spectral pyranometer-measured surface albedos were adjusted (63.6% and 80% of the ARM surface albedos for snow-free and snow cases, respectively) to account for the water and land components of the domain of 30 km × 30 km. Most of the radiative transfer model calculated SW↓sfc and SW↑TOA fluxes by using ARM and CERES cloud retrievals and the domain mean albedos as input agree with the ARM and CERES flux observations within 10Wm-2 for both snow-free and snow conditions. Sensitivity studies show that the ARM LWP and re retrievals are less dependent on solar zenith angle (SZA), but all retrieved optical depths increase with SZA. © 2016. American Geophysical Union."
"56829579700;14019399400;55740664200;56829592600;","A one-year study of the diurnal cycle of meteorology, clouds and radiation in the West African Sahel region",2016,"10.1002/qj.2623","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957849466&doi=10.1002%2fqj.2623&partnerID=40&md5=a0d388ccd1f72f200ff823ee65046406","The diurnal cycles of meteorological and radiation variables are analysed during the wet and dry seasons over the Sahel region of West Africa during 2006 using surface data collected by the Atmospheric Radiation Measurement (ARM) programme's Mobile Facility, satellite radiation measurements from the Geostationary Earth Radiation Budget (GERB) instrument aboard Meteosat 8, and reanalysis products from the National Centers for Environmental Prediction (NCEP). The meteorological analysis builds upon past studies of the diurnal cycle in the region by incorporating diurnal cycles of lower tropospheric wind profiles, thermodynamic profiles, integrated water vapour and liquid water measurements, and cloud radar measurements of frequency and location. These meteorological measurements are complemented by 3 h measurements of the diurnal cycles of the top-of-atmosphere (TOA) and surface short-wave (SW) and long-wave (LW) radiative fluxes and cloud radiative effects (CREs), and the atmospheric radiative flux divergence (RFD) and atmospheric CREs. Cirrus cloudiness during the dry season is shown to peak in coverage in the afternoon, while convective clouds during the wet season are shown to peak near dawn and have an afternoon minimum related to the rise of the lifting condensation level into the Saharan Air Layer. The LW and SW RFDs and CREs exhibit diurnal cycles during both seasons, but there is a relatively small difference in the LW cycles during the two seasons (10 - 30 W m-2 depending on the variable and time of day). Small differences in the TOA CREs during the two seasons are overwhelmed by large differences in the surface SW CREs, which exceed 100 W m-2. A significant surface SW CRE during the wet season combined with a negligible TOA SW CRE produces a diurnal cycle in the atmospheric CRE that is modulated primarily by the SW surface CRE, peaks at midday at ∼150 W m-2, and varies widely from day to day. © 2016 Royal Meteorological Society."
"8678477400;7004022660;6603129131;","Anthropogenic aerosol emissions and rainfall decline in Southwestern Australia: Coincidence or causality?",2016,"10.1175/JCLI-D-16-0082.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84997026850&doi=10.1175%2fJCLI-D-16-0082.1&partnerID=40&md5=136883c62835876e450d14b48f4ee9c2","It is commonly understood that the observed decline in precipitation in southwestern Australia during the twentieth century is caused by anthropogenic factors. Candidates therefore are changes to large-scale atmospheric circulations due to global warming, extensive deforestation, and anthropogenic aerosol emissions-all of which are effective on different spatial and temporal scales. This contribution focuses on the role of rapidly rising aerosol emissions from anthropogenic sources in southwestern Australia around 1970. An analysis of historical long-term rainfall data of the Bureau of Meteorology shows that southwestern Australia as a whole experienced a gradual decline in precipitation over the twentieth century. However, on smaller scales and for the particular example of the Perth catchment area, a sudden drop in precipitation around 1970 is apparent. Modeling experiments at a convection-resolving resolution of 3.3 km using the Weather Research and Forecasting (WRF) Model version 3.6.1 with the aerosol-aware Thompson-Eidhammer microphysics scheme are conducted for the period 1970-74. A comparison of four runs with different prescribed aerosol emissions and without aerosol effects demonstrates that tripling the pre-1960s atmospheric CCN and IN concentrations can suppress precipitation by 2%-9%, depending on the area and the season. This suggests that a combination of all three processes is required to account for the gradual decline in rainfall seen for greater southwestern Australia and for the sudden drop observed in areas along the west coast in the 1970s: changing atmospheric circulations, deforestation, and anthropogenic aerosol emissions. © 2016 American Meteorological Society."
"55961513200;7403681878;37025370400;","Optimizing Purdue-Lin Microphysics Scheme for Intel Xeon Phi Coprocessor",2016,"10.1109/JSTARS.2015.2496583","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949818128&doi=10.1109%2fJSTARS.2015.2496583&partnerID=40&md5=c3ee3e0554c775b3d2f4712b04076716","Due to severe weather events, there is a growing need for more accurate weather predictions. Climate change has increased both frequency and severity of such events. Optimizing weather model source code would result in reduced run times or more accurate weather predictions. One such weather model is the weather research and forecasting (WRF) model, which is designed for both numerical weather prediction (NWP) and atmospheric research. The WRF software infrastructure consists of several components such as dynamic solvers and physics schemes. Purdue-Lin scheme is a relatively sophisticated microphysics scheme in the WRF model. The scheme includes six classes of hydro meteors: 1) water vapor; 2) cloud water; 3) raid; 4) cloud ice; 5) snow; and 6) graupel. The scheme is very suitable for massively parallel computation as there are no interactions among horizontal grid points. Thus, we present our optimization results for the Purdue-Lin microphysics scheme. Those optimizations included improved vectorization of the code to utilize multiple vector units inside each processor code better. Performed optimizations improved the performance of the original unmodified Purdue-Lin microphysics code running natively on Xeon Phi 7120P by a factor of 4.7×. Similarly, the same optimizations improved the performance of the Purdue-Lin microphysics scheme on a dual socket configuration of eight core Intel Xeon E5-2670 CPUs by a factor of 1.3 × compared to the original code. © 2008-2012 IEEE."
"34976226000;14042251700;","Strong ocean-atmosphere interactions during a short-term hot Event over the western Pacific warm pool in response to El Niño",2016,"10.1175/JCLI-D-15-0595.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992377906&doi=10.1175%2fJCLI-D-15-0595.1&partnerID=40&md5=3faaa87d1237dc6455bb65e6e29cc25d","A short-term hot event with a very high sea surface temperature (SST = 30°C) occurred in the western Pacific warm pool during November 2006. The interactions between this ocean hot event, atmospheric convection, and large-scale dynamics are studied using satellite observations, buoy measurements, air-sea fluxes analysis, and global reanalysis. It is shown that SST variation and deep convection over the western Pacific behave like a remote response to the El Niño warm SST anomaly in the central Pacific that induces westward-moving atmospheric convection and equatorial waves. The large-scale subsidence associated with propagating convection not only promotes high SSTs in the western Pacific through establishing cloud-free conditions and increasing heat content in a thin ocean mixed layer, but also produces convective instability through capping substantial water vapor in the lower troposphere. Under the precondition of convective instability and the steering of tropical easterlies, some convective systems propagate coherently from the central to western Pacific and intensify. In particular, new cloud clusters are dynamically attracted to the warmest oceans with maximum atmospheric instability. The enhanced convective activity then transfers oceanic energy into the atmosphere, strengthens upper-ocean mixing, and returns the positive SST anomalies to more typical values. In such a coupled system, synoptic-scale convective activities at an interval of 5-8 days are selectively amplified and thus are filtered to an intraseasonal (20-30-day) oscillation, depending on the phase of the hot event over the western Pacific. The observed evidence has implications for the predictability of short-term climate, and it offers critical information for validating the coupled ocean-atmosphere dynamics in climate models. © 2016 American Meteorological Society."
"55440589800;6602929454;","Validation of the bureau of meteorology's global, diffuse, and direct solar exposure forecasts using the ACCESS numerical weather prediction systems",2016,"10.1175/JAMC-D-15-0031.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961661944&doi=10.1175%2fJAMC-D-15-0031.1&partnerID=40&md5=bd4e99012c26d5aac878b9831c283046","Forecast solar exposure fields produced by the Australian Bureau of Meteorology's updated numerical weather prediction systems were validated against multiple sites for the 2012 calendar year. The updated systems are denoted as the Australian Community Climate and Earth-System Simulator (ACCESS) model and became operational in August 2010. The systems are based on the Met Office's Unified Model and feature improved assimilation methods and radiation parameterizations that were expected to greatly improve forecasts of solar exposure several days in advance. In this study forecasts of global, direct, and diffuse exposure from the mesoscale model ACCESS-A were validated. Statistics were generated for all-sky and clear-sky conditions. Additionally, evaluation of the model's forecast exposure through single-layer low clouds was conducted. Results show an improvement in global forecasts relative to the older operational model; however, forecasts of diffuse and direct exposure still suffer from large biases. These can be attributed to the choices of the asymmetry factor used in the two-stream approximation for incoming radiation, which determines scattering of the direct beam through clouds. © 2016 American Meteorological Society."
"12778352600;55541369600;37088140000;23006934800;35925570700;7006894780;56203143700;57188656575;57188652894;37119101700;57188656145;56157698400;56291005300;7401962278;","Mobile measurement techniques for local and micro-scale studies in urban and topo-climatology",2016,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962106904&partnerID=40&md5=5cf628b111a9bdff2b55191a1b876546","Technical development during the last two decades has brought new potential and new applications for mobile measurements. In this paper, we present six case studies where mobile measurement devices were used to acquire data for meteorological and climatological research. Three case studies deal with groundbased mobile measurements - on buses for urban climate measurements and on a vessel on a lake - and three with airborne platforms - on a cable car and on an unmanned aerial vehicle for vertical soundings and on a tethered balloon sonde for cloud physics. For each study, we describe the measurement set-up and address the potential and drawbacks of these applications. At the end, we discuss general aspects related to mobile observations especially concerning the time and space dimension of measurements."
"7202899330;7102171439;57203722524;","The super greenhouse effect in a changing climate",2016,"10.1175/JCLI-D-15-0234.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987708350&doi=10.1175%2fJCLI-D-15-0234.1&partnerID=40&md5=410a6614387c7b5c3c3258cd40005715","In all outputs of the 1%yr-1 increase inCO2 climate model experiments archived under the World Climate Research Programme's (WCRP) phase 5 of the Coupled Model Intercomparison Project (CMIP5), regions exist in the low latitudes where both the clear-sky and all-sky OLR decrease with surface warming. These are identified as regions of positive longwave feedback and are regions of a super greenhouse effect (SGE). These SGE regions are identified from feedback analysis of the 4 × CO2 abrupt experiments of CMIP5, and despite their existence, there is little agreement across models as to the magnitude of the effect. The general effects of clouds on the SGE are to amplify the clear-sky SGE, but there is also poor agreement on the magnitude of the amplification that varies by an order of magnitude across models. Sensitivity analyses indicate that localized SGE regions are spatially aligned with a large moistening of the upper troposphere. The reduction in clear-sky OLR arises from a reduction in emission in the far IR with nonnegligible contributions from mid-IR emission from the midtroposphere. When viewed in the broader context of meridional heat transport, it is found that of the 1.03-PW rate of heat gained globally, 0.8 PW is absorbed in the tropics and is contributed almost equally by reductions in clear-sky longwave emission (i.e., the clear-sky SGE) and increased absorbed clear-sky solar radiation associated with increased water vapor. The processes that define the clear-sky SGE are shown to be fundamental to the way models accumulate heat and then transport it poleward. © 2016 American Meteorological Society."
"7004364155;6506504165;8891521600;57197641367;7404655255;","CERES top-of-atmosphere earth radiation budget climate data record: Accounting for in-orbit changes in instrument calibration",2016,"10.3390/rs8030182","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962589165&doi=10.3390%2frs8030182&partnerID=40&md5=19db0118a854340862e3c4d2085ca34c","The Clouds and the Earth's Radiant Energy System (CERES) project provides observations of Earth's radiation budget using measurements from CERES instruments onboard the Terra, Aqua and Suomi National Polar-orbiting Partnership (S-NPP) satellites. As the objective is to create a long-term climate data record, it is necessary to periodically reprocess the data in order to incorporate the latest calibration changes and algorithm improvements. Here, we focus on the improvements and validation of CERES Terra and Aqua radiances in Edition 4, which are used to generate higher-level climate data products. Onboard sources indicate that the total (TOT) channel response to longwave (LW) radiation has increased relative to the start of the missions by 0.4% to 1%. In the shortwave (SW), the sensor response change ranges from -0.4% to 0.6%. To account for in-orbit changes in SW spectral response function (SRF), direct nadir radiance comparisons between instrument pairs on the same satellite are made and an improved wavelength dependent degradation model is used to adjust the SRF of the instrument operating in a rotating azimuth plane scan mode. After applying SRF corrections independently to CERES Terra and Aqua, monthly variations amongst these instruments are highly correlated and the standard deviation in the difference of monthly anomalies is 0.2 Wm-2 for ocean and 0.3 Wm-2 for land/desert. Additionally, trends in CERES Terra and Aqua monthly anomalies are consistent to 0.21 Wm-2 per decade for ocean and 0.31 Wm-2 per decade for land/desert. In the LW, adjustments to the TOT channel SRF are made to ensure that removal of the contribution from the SW portion of the TOT channel with SW channel radiance measurements during daytime is consistent throughout the mission. Accordingly, anomalies in day-night LW difference in Edition 4 are more consistent compared to Edition 3, particularly for the Aqua land/desert case. © 2016 by the authors."
"7403248284;57188769414;56365039300;56915535600;55568519584;","Assessing the Effects of Spatial Resolution on Regional Climate Model Simulated Summer Temperature and Precipitation in China: A Case Study",2016,"10.1155/2016/7639567","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962798153&doi=10.1155%2f2016%2f7639567&partnerID=40&md5=3af2b138f899f906a088521e8bac5ca7","The regional climate model, RegCM3, is used to simulate the 2004 summer surface air temperature (SAT) and precipitation at different horizontal (i.e., 30, 60, and 90 km) and vertical resolutions (i.e., 14, 18, and 23 layers). Results showed that increasing resolution evidently changes simulated SATs with regional characteristics. For example, simulated SATs are apparently better produced when horizontal resolution increases from 60 to 30 km under the 23 layers. Meanwhile, the SATs over the entire area are more sensitive to vertical resolution than horizontal resolution. The subareas present higher sensitivities than the total area, with larger horizontal resolution effects than those of vertical resolution. For precipitation, increasing resolution shows higher impact compared to SAT, with higher sensitivity induced by vertical resolution than by horizontal resolution, especially in rainy South China. The best SAT/precipitation can be produced only when the horizontal and vertical resolutions are reasonably configured. This indicates that different resolutions lead to different atmospheric thermodynamic states. Because of the dry climate and low soil heat capacity in Northern China, resolution changes easily modify surface energy fluxes, hence the SAT; due to the rainy and humid climate in South China, resolution changes likely strongly influence grid-scale structure of clouds and therefore precipitation. © 2016 Xin-Min Zeng et al."
"16064843400;7102953444;6602733593;7003841561;55636624100;56152199100;","Interannual variation of global net radiation flux as measured from space",2016,"10.1002/2015JD024112","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978796234&doi=10.1002%2f2015JD024112&partnerID=40&md5=08a6e58c2d81476c720739a2ba214bba","The global net radiation flux (NRF) in and out of the climate system at the top of the atmosphere (TOA) varies at interannual time scales, reflecting the complexity of the processes responsible for attaining global energy equilibrium. These processes are investigated in this study using the previously unexplored data acquired by a bolometric type sensor installed in the PICARD microsatellite. The obtained anomalies in the NRF (PICARD-NRF) are compared to the global NRF changes at the TOA measured by the Clouds and Earth’s Radiant Energy System mission (CERES-NRF). The interanual PICARD-NRF is strongly correlated with the matching period CERES-NRF; the bootstrapped correlation at the 95%(+0.85 and +0.97) confidence intervals is +0.93. Consistency in the interannual variability in the NRF derived by two completely independent measurement systems enhances confidence in the estimated magnitude of these variations. To reveal the possible drivers of the NRF interannual variability, the NRF values were compared with the multivariate El Niño-Southern Oscillation index. © 2016. American Geophysical Union. All Rights Reserved."
"54279395000;15769236000;7801654745;25925792100;6603757377;","Climatic controls and climate proxy potential of Lewis Glacier, Mt. Kenya",2016,"10.5194/tc-10-133-2016","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84998666772&doi=10.5194%2ftc-10-133-2016&partnerID=40&md5=c65330270fe608e040b79224520e0288","The Lewis Glacier on Mt. Kenya is one of the best studied tropical glaciers and has experienced considerable retreat since a maximum extent in the late 19th century (L19). From distributed mass and energy balance modelling, this study evaluates the current sensitivity of the surface mass and energy balance to climatic drivers, explores climate conditions under which the L19 maximum extent might have been sustained, and discusses the potential for using the glacier retreat to quantify climate change. Multi-year meteorological measurements at 4828 m provide data for input, optimization, and evaluation of a spatially distributed glacier mass balance model to quantify the exchanges of energy and mass at the glacier–atmosphere interface. Currently the glacier loses mass due to the imbalance between insufficient accumulation and enhanced melt, because radiative energy gains cannot be compensated by turbulent energy sinks. Exchanging model input data with synthetic climate scenarios, which were sampled from the meteorological measurements and account for coupled climatic variable perturbations, reveals that the current mass balance is most sensitive to changes in atmospheric moisture (via its impact on solid precipitation, cloudiness, and surface albedo). Positive mass balances result from scenarios with an increase of annual (seasonal) accumulation of 30 % (100 %), compared to values observed today, without significant changes in air temperature required. Scenarios with lower air temperatures are drier and associated with lower accumulation and increased net radiation due to reduced cloudiness and albedo. If the scenarios currently producing positive mass balances are applied to the L19 extent, negative mass balances are the result, meaning that the conditions required to sustain the glacier in its L19 extent are not reflected in today’s meteorological observations using model parameters optimized for the present-day glacier. Alternatively, a balanced mass budget for the L19 extent can be achieved by changing both climate and optimized gradients (used to extrapolate the meteorological measurements over the glacier) in a manner that implies a distinctly different coupling between the glacier’s local surface-air layer and its surrounding boundary layer. This result underlines the difficulty of deriving palaeoclimates for larger glacier extents on the basis of modern measurements of small glaciers. © Author(s) 2016."
"6701718281;7004474392;6603371044;55559573300;","Quantitative sensitivity analysis of physical parameterizations for cases of deep convection in the NASA GEOS-5",2016,"10.1175/JCLI-D-15-0250.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957806825&doi=10.1175%2fJCLI-D-15-0250.1&partnerID=40&md5=842c4303aef7d4fff317c224f2da286f","Parameterization of processes that occur on length scales too small to resolve on a computational grid is a major source of uncertainty in global climate models. This study investigates the relative importance of a number of parameters used in the Goddard Earth Observing System Model, version 5 (GEOS-5), atmospheric general circulation model, focusing on cloud, convection, and boundary layer parameterizations. Latin hypercube sampling is used to generate a few hundred sets of 19 candidate physics parameters, which are subsequently used to generate ensembles of single-column model realizations of cloud content, precipitation, and radiative fluxes for four different field campaigns. A Gaussian process model is then used to create a computationally inexpensive emulator for the simulation code that can be used to determine a measure of relative parameter sensitivity by sampling the response surface for a very large number of input parameter sets. Parameter sensitivities are computed for different geographic locations and seasons to determine whether the intrinsic sensitivity of the model parameterizations changes with season and location. The results indicate the same subset of parameters collectively control the model output across all experiments, independent of changes in the environment. These are the threshold relative humidity for cloud formation, the ice fall speeds, convective and large-scale autoconversion, deep convection relaxation time scale, maximum convective updraft diameter, and minimum ice effective radius. However, there are differences in the degree of parameter sensitivity between continental and tropical convective cases, as well as systematic changes in the degree of parameter influence and parameter-parameter interaction. © 2016 American Meteorological Society."
"7202715936;57192393249;7005441425;57192398726;","Developing MODIS-based cloud climatologies to aid species distribution modeling and conservation activities",2016,"10.21425/f58329532","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006167781&doi=10.21425%2ff58329532&partnerID=40&md5=480c1f404d94d6f940203a3c04592074","WorldClim (Hijmans et al. 2005) has been the de-facto source of basic climatological analyses for most species distribution modeling research and conservation science applications because of its global coverage and fine (< 1 km) spatial resolution. However, it has been recognized since its development that there are limitations in data-poor regions, especially with regard to the precipitation analyses. Here we describe procedures to develop a satellite-based daytime cloudiness climatology that better reflects the variations in vegetation cover in many regions of the globe than do the WorldClim precipitation products. Moderate Resolution Imaging Spectroradiometer (MODIS) imagery from the National Aeronautics and Space Administration (NASA) Terra and Aqua sun-synchronous satellites have recently been used to develop multi-year climatologies of cloudiness. Several procedures exist for developing such climatologies. We first discuss a simple procedure that uses brightness thresholds to identify clouds. We compare these results with those from a more complex procedure: the MODIS Cloud Mask product, recently averaged into climatological products by Wilson and Jetz (2016). We discuss advantages and limitations of both approaches. We also speculate on further work that will be needed to improve the usefulness of these MODIS-based climatologies of cloudiness. Despite limitations of current MODIS-based climatology products, they have the potential to greatly improve our understanding of the distribution of biota across the globe. We show examples from oceanic islands and arid coastlines in the subtropics and tropics where the MODIS products should be of special value in predicting the observed vegetation cover. Some important applications of reliable climatologies based on MODIS imagery products will include 1) helping to restore long-degraded cloud-impacted environments; 2) improving estimations of the spatial distribution of cloud-impacted species; and 3) helping to identify areas for rapid biological assessments. The last application can even benefit from qualitative perusal of the current MODIS climatologies. © 2016 the authors; journal compilation."
"56379892200;56284543100;","The temporal evolution of a long-lived contrail cirrus cluster: Simulations with a global climate model",2016,"10.1002/2015JD024475","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84963823023&doi=10.1002%2f2015JD024475&partnerID=40&md5=609bb926c439da0bef625e564e1bf78d","The representation of contrail cirrus in climate models has advanced in the last years tremendously. Nevertheless, uncertainties in particular regarding the representation of contrail microphysics still remain. Properties of young contrail cirrus differ from those of natural cirrus due to the large ice crystal number concentration common in contrails. Consequently, microphysical process rates in contrail cirrus, which control its lifetime, can be very different to those in natural cirrus. We extend a contrail cirrus scheme within a climate model by implementing a microphysical two-moment scheme and study the life cycle of a contrail cirrus cluster. In an idealized experiment we study the properties and microphysical process rates of a contrail cirrus cluster in a large and long-lived ice supersaturated region. We find that at flight level contrail cirrus display their typical high ice crystal number concentration (of about 10-100 cm-3) for a few hours with far lower densities in lower levels caused by sedimentation. After about 7 h contrail cirrus have spread considerably so that even at flight level associated ice crystal number concentrations have dropped to values that prohibit fast relaxation of ice supersaturation. The reduced ice crystal number and the resulting limited water uptake in the contrail cirrus limit the lifetime of the contrail cirrus cluster to about 10 h even though surrounding conditions would be still favorable for contrail cirrus persistence. In our case studies, contrail cirrus resembles natural cirrus regarding their ice crystal number concentration and size after 5-7 h. © 2016. American Geophysical Union. All Rights Reserved."
"56537827700;6603546080;48662824200;7006495234;55916098100;7006783796;8719703500;","A consistent AVHRR visible calibration record based on multiple methods applicable for the NOAA Degrading Orbits. Part I: Methodology",2016,"10.1175/JTECH-D-16-0044.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85013464146&doi=10.1175%2fJTECH-D-16-0044.1&partnerID=40&md5=9b35e9b81312996a0afa001e7ac64f03","The 35-yr NOAA Advanced Very High Resolution Radiometer (AVHRR) observation record offers an excellent opportunity to study decadal climate variability, provided that all participating AVHRR instruments are calibrated on a consistent radiometric scale. Because of the lack of onboard calibration systems, the solar imaging channels of the AVHRR must be vicariously calibrated using invariant Earth targets as a calibrated reference source. The greatest challenge in calibrating the AVHRR dataset is the orbit degradation of the NOAA satellites, which eventually drift into a terminator orbit several years after launch. Therefore, the invariant targets must be characterized over the full range of solar zenith angles (SZAs) sampled by the satellite instrument. This study outlines a multiple invariant Earth target calibration approach specifically designed to account for the degrading NOAA orbits. The desert, polar ice, and deep convective cloud (DCC) invariant targets are characterized over all observed SZAs using NOAA-16 AVHRR measurements, which are referenced to the Aqua MODIS Collection 6 calibration via direct transfer of the MODIS calibration to the NOAA-16 AVHRR instrument using simultaneous nadir overpass (SNO) observations over the North Pole. The multiple invariant target calibrations are combined using the inverse of their temporal variance to optimize the resulting calibration stability. The NOAA-18 AVHRR gains derived using the desert, polar ice, and DCC targets, as well as from SNO, were found consistent within 1%, thereby validating that the Aqua MODIS calibration is effectively transferred to the reference calibration targets. The companion paper, Part II, applies the methodology across the AVHRR record to derive the sensor-specific calibration coefficients. © 2016 American Meteorological Society."
"7102953444;","Decadal changes in radiative fluxes at land and ocean surfaces and their relevance for global warming",2016,"10.1002/wcc.372","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957725522&doi=10.1002%2fwcc.372&partnerID=40&md5=628a2e1272bc2377a0359dc14a37358b","Anthropogenic interference with climate occurs primarily through modification of radiative fluxes in the climate system. Increasing releases of greenhouse gases into the atmosphere lead to an enhancement of thermal radiation from the atmosphere to the surface by presently about 2 W m-2 per decade, thereby causing global warming. Yet not only thermal radiation undergoes substantial decadal changes at the Earth surface, but also incident solar radiation (SSR), often in line with changes in aerosol emissions. Land-based observations suggest widespread declines in SSR from 1950s to 1980s ('global dimming'), a partial recovery ('brightening') since mid-1980s, and indication for an 'early' brightening in 1930s and 1940s. No similar extended observational records are available over oceans. However, modeling studies, conceptual frameworks and available satellite-derived records point to the existence of decadal SSR variations also over oceans. SSR changes overall match with decadal variations in observed warming rates, suggesting that SSR variations may effectively modulate greenhouse gas-induced warming. Specifically, on the Northern Hemisphere, the lack of warming from 1950s to 1980s and its subsequent acceleration in the 1990s fits to the trend reversal from dimming to brightening and associated changes in air pollution levels. From the 1950s to 1980s no warming was also observed over Northern Hemispheric Oceans, in line with conceptual ideas that subtle aerosol changes in pristine ocean areas, effectively amplified by aerosol-cloud interactions, can substantially alter SSR, thereby modulating Sea Surface Temperatures. On the Southern Hemisphere, the absence of significant aerosol levels fits to the observed stable (greenhouse gas-induced) warming rates since the 1950s. © 2016 Wiley Periodicals, Inc."
"7102913661;55314628400;7102336894;7006497590;8261329600;14048087800;57218185429;8359591200;35105101800;7006372688;55355957400;24481931900;7401875806;7004643405;36616603800;16480965400;57200319386;37040691400;7006025236;56704589000;7005902263;","Convective transport and scavenging of peroxides by thunderstorms observed over the central U.S. during DC3",2016,"10.1002/2015JD024570","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84966546466&doi=10.1002%2f2015JD024570&partnerID=40&md5=e87a3a43dcde9c196bb5d7d156aa7da2","One of the objectives of the Deep Convective Clouds and Chemistry (DC3) field experiment was to determine the scavenging of soluble trace gases by thunderstorms. We present an analysis of scavenging of hydrogen peroxide (H2O2) and methyl hydrogen peroxide (CH3OOH) from six DC3 cases that occurred in Oklahoma and northeast Colorado. Estimates of H2O2 scavenging efficiencies are comparable to previous studies ranging from 79 to 97% with relative uncertainties of 5–25%. CH3OOH scavenging efficiencies ranged from 12 to 84% with relative uncertainties of 18–558%. The wide range of CH3OOH scavenging efficiencies is surprising, as previous studies suggested that CH3OOH scavenging efficiencies would be &lt;10%. Cloud chemistry model simulations of one DC3 storm produced CH3OOH scavenging efficiencies of 26–61% depending on the ice retention factor of CH3OOH during cloud drop freezing, suggesting ice physics impacts CH3OOH scavenging. The highest CH3OOH scavenging efficiencies occurred in two severe thunderstorms, but there is no obvious correlation between the CH3OOH scavenging efficiency and the storm thermodynamic environment. We found a moderate correlation between the estimated entrainment rates and CH3OOH scavenging efficiencies. Changes in gas-phase chemistry due to lightning production of nitric oxide and aqueous-phase chemistry have little effect on CH3OOH scavenging efficiencies. To determine why CH3OOH can be substantially removed from storms, future studies should examine effects of entrainment rate, retention of CH3OOH in frozen cloud particles during drop freezing, and lightning-NOx production. © 2016. American Geophysical Union. All Rights Reserved."
"55067058700;55729666100;57194742863;57211811362;55683878900;55613112200;6602639521;7004864963;7007160874;7004462227;","Rupturing of biological spores as a source of secondary particles in Amazonia",2016,"10.1021/acs.est.6b02896","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021852298&doi=10.1021%2facs.est.6b02896&partnerID=40&md5=b3259eea97ae693f7b1fc70f7e717588","Airborne biological particles, such as fungal spores and pollen, are ubiquitous in the Earth's atmosphere and may influence the atmospheric environment and climate, impacting air quality, cloud formation, and the Earth's radiation budget. The atmospheric transformations of airborne biological spores at elevated relative humidity remain poorly understood and their climatic role is uncertain. Using an environmental scanning electron microscope (ESEM), we observed rupturing of Amazonian fungal spores and subsequent release of submicrometer size fragments after exposure to high humidity. We find that fungal fragments contain elements of inorganic salts (e.g., Na and Cl). They are hygroscopic in nature with a growth factor up to 2.3 at 96% relative humidity, thus they may potentially influence cloud formation. Due to their hygroscopic growth, light scattering cross sections of the fragments are enhanced by up to a factor of 10. Furthermore, rupturing of fungal spores at high humidity may explain the bursting events of new particle formation in Amazonia. © 2016 American Chemical Society."
"36538539800;55802355600;56942554300;55624488227;7004444634;7202010686;","Application of WRF/Chem over East Asia: Part II. Model improvement and sensitivity simulations",2016,"10.1016/j.atmosenv.2015.07.023","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949626339&doi=10.1016%2fj.atmosenv.2015.07.023&partnerID=40&md5=af5ad6763e275894dd59e726f5eae6a3","To address the problems and limitations identified through a comprehensive evaluation in Part I paper, several modifications are made in model inputs, treatments, and configurations and sensitivity simulations with improved model inputs and treatments are performed in this Part II paper. The use of reinitialization of meteorological variables reduces the biases and increases the spatial correlations in simulated temperature at 2-m (T2), specific humidity at 2-m (Q2), wind speed at 10-m (WS10), and precipitation (Precip). The use of a revised surface drag parameterization further reduces the biases in simulated WS10. The adjustment of only the magnitudes of anthropogenic emissions in the surface layer does not help improve overall model performance, whereas the adjustment of both the magnitudes and vertical distributions of anthropogenic emissions shows moderate to large improvement in simulated surface concentrations and column mass abundances of species in terms of domain mean performance statistics, hourly and monthly mean concentrations, and vertical profiles of concentrations at individual sites. The revised and more advanced dust emission schemes can help improve PM predictions. Using revised upper boundary conditions for O3 significantly improves the column O3 abundances. Using a simple SOA formation module further improves the predictions of organic carbon and PM2.5. The sensitivity simulation that combines all above model improvements greatly improves the overall model performance. For example, the sensitivity simulation gives the normalized mean biases (NMBs) of -6.1% to 23.8% for T2, 2.7-13.8% for Q2, 22.5-47.6% for WS10, and -9.1% to 15.6% for Precip, comparing to -9.8% to 75.6% for T2, 0.4-23.4% for Q2, 66.5-101.0% for WS10, and 11.4%-92.7% for Precip from the original simulation without those improvements. It also gives the NMBs for surface predictions of -68.2% to -3.7% for SO2, -73.8% to -20.6% for NO2, -8.8%-128.7% for O3, -61.4% to -26.5% for PM2.5, and -64.0% to 7.2% for PM10, comparing to -84.2% to -44.5% for SO2, -88.1% to -44.0% for NO2, -11.0%-160.3% for O3, -63.9% to -25.2% for PM2.5, and -68.9%-33.3% for PM10 from the original simulation. The improved WRF/Chem is applied to estimate the impact of anthropogenic aerosols on regional climate and air quality in East Asia. Anthropogenic aerosols can increase cloud condensation nuclei, aerosol optical depth, cloud droplet number concentrations, and cloud optical depth. They can decrease surface net radiation, temperature at 2-m, wind speed at 10-m, planetary boundary layer height, and precipitation through various direct and indirect effects. These changes in turn lead to changes in chemical predictions in a variety of ways. © 2015 Elsevier Ltd."
"8084443000;16304787700;55682751100;57190070786;8728117300;24332608900;35369341900;6506496327;6603000763;11940634500;35305397000;55858251100;6603082247;7003717426;6603186492;7004031192;","Evidence of atmospheric nanoparticle formation from emissions of marine microorganisms",2016,"10.1002/2016GL069389","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977117678&doi=10.1002%2f2016GL069389&partnerID=40&md5=9d773e580cdc975e6dae28397cab9e28","Earth, as a whole, can be considered as a living organism emitting gases and particles into its atmosphere, in order to regulate its own temperature. In particular, oceans may respond to climate change by emitting particles that ultimately will influence cloud coverage. At the global scale, a large fraction of the aerosol number concentration is formed by nucleation of gas-phase species, but this process has never been directly observed above oceans. Here we present, using semicontrolled seawater-air enclosures, evidence that nucleation may occur from marine biological emissions in the atmosphere of the open ocean. We identify iodine-containing species as major precursors for new particle clusters' formation, while questioning the role of the commonly accepted dimethyl sulfide oxidation products, in forming new particle clusters in the region investigated and within a time scale on the order of an hour. We further show that amines would sustain the new particle formation process by growing the new clusters to larger sizes. Our results suggest that iodine-containing species and amines are correlated to different biological tracers. These observations, if generalized, would call for a substantial change of modeling approaches of the sea-to-air interactions. ©2016. American Geophysical Union. All Rights Reserved."
"55769632600;35926838500;54782251800;55676495800;","Correlation between the spectral features and electric field changes for natural lightning return stroke followed by continuing current with M-components",2016,"10.1002/2016JD025314","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979792041&doi=10.1002%2f2016JD025314&partnerID=40&md5=ac2bc0c886f0cbda061085a00ffad467","According to the high time-resolved spectra of two first and a subsequent return strokes and the following continuing current processes overlapped with M-components in three natural cloud-to-ground lightning, the correlation between the total intensity of ionic lines in the spectra and the corresponding amplitude of electric field change and that between the total intensity of the spectra and the apparent diameter of the discharge channel have been investigated. Linear correlations have been found for the above two sets of parameters. The luminous properties along the channel show that the total intensity of ionic lines in the spectra for both the return stroke and M-components decreases with increasing height along the channel. The total intensity of the spectra and the apparent diameter for the return stroke also go down with increase of the height, while those for M-components do the reverse. © 2016. American Geophysical Union. All Rights Reserved."
"57203084853;24466769400;35503830800;57205497429;","Isentropic transport and the seasonal cycle amplitude of CO2",2016,"10.1002/2016JD025109","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978919861&doi=10.1002%2f2016JD025109&partnerID=40&md5=9017720f2a38a0368d4e29a6472678a6","Carbon-concentration feedbacks and carbon-climate feedbacks constitute one of the largest sources of uncertainty in future climate. Since the beginning of the modern atmospheric CO2 record, seasonal variations in CO2 have been recognized as a signal of the metabolism of land ecosystems, and quantitative attribution of changes in the seasonal cycle amplitude (SCA) of CO2 to ecosystem processes is critical for understanding and projecting carbon-climate feedbacks far into the 21st Century. Here the impact of surface carbon fluxes on the SCA of CO2 throughout the Northern Hemisphere troposphere is investigated, paying particular attention to isentropic transport across latitudes. The analysis includes both a chemical transport model GOES-Chem and an idealized tracer in a gray-radiation aquaplanet. The results of the study can be summarized by two main conclusions: (1) the SCA of CO2roughly follows surfaces of constant potential temperature, which can explain the observed increase in SCA with latitude along pressure surfaces and (2) increasing seasonal fluxes in lower latitudes have a larger impact on the SCA of CO2 throughout most of the troposphere compared to increasing seasonal fluxes in higher latitudes. These results provide strong evidence that recently observed changes in the SCA of CO2 at high northern latitudes (poleward of 60°N) are likely driven by changes in midlatitude surface fluxes, rather than changes in Arctic fluxes. © 2016. American Geophysical Union. All Rights Reserved."
"23099664200;56031970400;7203019582;","Urban heat island patterns and their dynamics based on an urban climate measurement network",2016,"10.15201/hungeobull.65.2.2","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977575228&doi=10.15201%2fhungeobull.65.2.2&partnerID=40&md5=dd50cd3d9a7df9d1181c2869aee4d2bf","In this paper the spatial pattern of Urban Heat Island (UHI) and its dynamical background are analysed. Furthermore, we examined the annual, seasonal and diurnal characteristics of UHI according to the Local Climate Zones (LCZs). The analysis was performed using one year (between June 2014 and May 2015) dataset from the measurement network of Szeged (Hungary). This network consists of 24 stations measuring air temperature and relative humidity. In the installation of the network the representativeness played an important role in order to that the stations represents their LCZs. We examined the thermal reactions during average and ideal conditions using the so-called weather factor. Our results show that the UHI is stronger in the compactly built zones and there are great differences between the zones. The greatest values appear in summer, while the difference is small in winter. The UHI starts to develop at sunset and exists through approximately 9–10 hours and differences are about 2 °C larger in case of ideal days, when the conditions (wind, cloud cover) are appropriate to the strong development of the UHI. The cooling rates show that the first few hours after sunset are determinative for the developing of UHI. In addition, the effect of UHI on annual mean temperature is also significant. © 2016, Reasearch Centre for Astronomy and Earth Sciences Hungarian Academy. All rights reserved."
"15726427000;36097134700;","Extreme convection and tropical climate variability: Scaling of cold brightness temperatures to sea surface temperature",2016,"10.1175/JCLI-D-15-0214.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017965875&doi=10.1175%2fJCLI-D-15-0214.1&partnerID=40&md5=c45c14e6a5e2f0fa3a300152b0e508a8","Changes in tropical convective events provide a test bed for understanding changes of extreme convection in a warming climate. Because convective cloud top in deep convection is associated with cold brightness temperatures (BTs) in infrared window channels, variability in global convective events can be studied by spaceborne measurements of BTs. The sensitivity of BTs, directly measured by an Atmospheric Infrared Sounder (AIRS) window channel, to natural changes (the seasonal cycle and El Niño-Southern Oscillation) in tropical sea surface temperature (SST) is examined. It is found that tropical average BTs (over the ocean) at the low percentiles of their probability distributions scale with tropical average SSTs (higher SST leading to colder BTs), with the lower percentiles being significantly more sensitive to changes in SST. The sensitivity is reduced for high percentiles of BT and is insignificant for the median BT, and has similar magnitudes for the two natural changes used in the study. The regions where the lower-percentile BTs are most sensitive to SST are near the edges of the convection active areas (intertropical convergence zone and South Pacific convergence zone), including areas with active tropical cyclone activity. Since cold BTs of lower percentiles represent stronger convective events, this study provides, for the first time, global observational evidence of higher sensitivity of changes in stronger convective activity to a changing SST. This result has important potential implications in answering the key climate question of how severe tropical convection will change in a warming world. © 2016 American Meteorological Society."
"55944537900;35106150700;7005742190;","A new class of quality controls for micrometeorological data in complex tropical environments",2016,"10.1175/JTECH-D-15-0062.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958160459&doi=10.1175%2fJTECH-D-15-0062.1&partnerID=40&md5=28058b487fe36cc705105f5d9f0f2770","Quality control is a particularly demanding problem for micrometeorological studies in complex environments. With the transition to electronic sensing and storage of climate data in high temporal resolution, traditional approaches of homogenization are insufficient for addressing the small-scale variability and spatial heterogeneity of the data. This problem can be successfully addressed by introducing a new class of control procedures based on the physical and climatological relations between different climate variables. The new approach utilizes knowledge about the interdependency of air temperature, precipitation, radiation, relative air humidity, cloud cover, and visibility to develop empirical functions for determining the probability margins for the co-occurrence of specific conditions in tropical mountains and deserts. It can also be applied to other geographic settings by adjusting the parameters derived from the data itself. All procedures are integrated into a processing chain with feedback loops and combined with conventional logical and statistical checks, which enables it to detect small errors that normally pass unnoticed. The algorithms are also adapted to incorporate the short time steps of the original data to retain the potential for detailed process analyses. © 2016 American Meteorological Society."
"55802246600;56075881200;7102266120;6506328135;34881780600;55522498000;8042408300;","Assessing impacts of PBL and surface layer schemes in simulating the surface-atmosphere interactions and precipitation over the tropical ocean using observations from AMIE/DYNAMO",2016,"10.1175/JCLI-D-16-0040.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039050761&doi=10.1175%2fJCLI-D-16-0040.1&partnerID=40&md5=6e7365590fa529f7716b6cff25f4dab2","Accuracy of turbulence parameterization in representing planetary boundary layer (PBL) processes and surface-atmosphere interactions in climate models is critical for predicting the initiation and development of clouds. This study 1) evaluates WRF Model-simulated spatial patterns and vertical profiles of atmospheric variables at various spatial resolutions and with different PBL, surface layer, and shallow convection schemes against measurements; 2) identifies model biases by examining the moisture tendency terms contributed by PBL and convection processes through nudging experiments; and 3) investigates the main causes of these biases by analyzing the dependence of modeled surface fluxes on PBL and surface layer schemes over the tropical ocean. The results show that PBL and surface parameterizations have surprisingly large impacts on precipitation and surface moisture fluxes over tropical oceans. All of the parameterizations tested tend to overpredict moisture in the PBL and free atmosphere and consequently result in larger moist static energy and precipitation. Moisture nudging tends to suppress the initiation of convection and reduces the excess precipitation. The reduction in precipitation bias in turn reduces the surface wind and latent heat (LH) flux biases, which suggests the positive feedback between precipitation and surface fluxes is responsible, at least in part, for the model drifts. The updated Kain-Fritsch cumulus potential (KF-CuP) shallow convection scheme tends to suppress the deep convection, consequently decreasing precipitation. The Eta Model surface layer scheme predicts more reasonable LH fluxes and LH-wind speed relationship than those for the MM5 scheme. The results help us identify sources of biases of current parameterization schemes in reproducing PBL processes, the initiation of convection, and intraseasonal variability of precipitation. © 2016 American Meteorological Society."
"55349680000;7003854772;","Remote sensing of the North American Laurentian Great Lakes' surface temperature",2016,"10.3390/rs8040286","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971659433&doi=10.3390%2frs8040286&partnerID=40&md5=ddd94887c6a02df89a5c4b48a8932f55","The Great Lakes Surface Temperature (GLST) is the key to understanding the effects of climate change on the Great Lakes (GL). This study provides the first techniques to retrieve pixel-based GLST under all sky conditions by merging skin temperature derived from the MODIS Land Surface Temperature (MOD11L2) and the MODIS Cloud product (MOD06L2) from 6 July 2001 to 31 December 2014, resulting in 18,807 scenes in total 9373 (9434) scenes for MOD11L2 (MOD06L2). The pixel-based GLST under all sky conditions was well-correlated with the in situ observations (R2 = 0.9102) with a cool bias of -1.10 °C and a root mean square error (RMSE) of 1.39 °C. The study also presents the long-term trends of GLST. Contrary to expectations, it decreased slightly due to the impact of an anomalously cold winter in 2013-2014. © 2016 by the authors."
"56883853200;57215596081;","The large-scale ocean dynamical effect on uncertainty in the tropical pacific SST warming pattern in CMIP5 models",2016,"10.1175/JCLI-D-16-0318.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994189408&doi=10.1175%2fJCLI-D-16-0318.1&partnerID=40&md5=f7aa944bebd6b057048fc7f6a7d661c4","This study investigates how intermodel differences in large-scale ocean dynamics affect the tropical Pacific sea surface temperature (SST) warming (TPSW) pattern under global warming, as projected by 32 models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). The largest cause of intermodel TPSW differences is related to the cloud-radiation feedback. After removing the effect of cloud-radiation feedback, the authors find that differences in ocean advection play the next largest role, explaining around 14% of the total intermodel variance in TPSW. Of particular importance are differences in climatological zonal overturning circulation among the models. With the robust enhancement of ocean stratification across models, models with relatively strong climatological upwelling tend to have relatively weak SST warming in the eastern Pacific. Meanwhile, the pronounced intermodel differences in ocean overturning changes contribute little to uncertainty in the TPSW pattern. The intermodel differences in climatological zonal overturning are found to be associated with the intermodel spread in climatological SST. In most CMIP5 models, there is a common cold tongue associated with an overly strong overturning in the climatology simulation, implying a La Niña-like bias in the TPSW pattern projected by the MME of the CMIP5 models. This provides further evidence for the projection that the TPSW pattern should be closer to an El Niño-like pattern than the MME projection. © 2016 American Meteorological Society."
"57216057737;7005669183;14060686500;6602389214;","Woody biomass estimation in a southwestern U.S. Juniper Savanna using LiDAR-derived clumped tree segmentation and existing allometries",2016,"10.3390/rs8060453","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84974822941&doi=10.3390%2frs8060453&partnerID=40&md5=49841cc313f884818a733458926add87","The rapid and accurate assessment of above ground biomass (AGB) of woody vegetation is a critical component of climate mitigation strategies, land management practices and process-based models of ecosystem function. This is especially true of semi-arid ecosystems, where the high variability in precipitation and disturbance regimes can have dramatic impacts on the global carbon budget by rapidly transitioning AGB between live and dead pools. Measuring regional AGB requires scaling ground-based measurements using remote sensing, an inherently challenging task in the sparsely-vegetated, spatially-heterogeneous landscapes characteristic of semi-arid regions. Here, we test the ability of canopy segmentation and statistic generation based on aerial LiDAR (light detection and ranging)-derived 3D point clouds to derive AGB in clumps of vegetation in a juniper savanna in central New Mexico. We show that single crown segmentation, often an error-prone and challenging task, is not required to produce accurate estimates of AGB. We leveraged the relationship between the volume of the segmented vegetation clumps and the equivalent stem diameter of the corresponding trees (R2 = 0.83, p &lt; 0.001) to drive the allometry for J. monosperma on a per segment basis. Further, we showed that making use of the full 3D point cloud from LiDAR for the generation of canopy object statistics improved that relationship by including canopy segment point density as a covariate (R2 = 0.91). This work suggests the potential for LiDAR-derived estimates of AGB in spatially-heterogeneous and highly-clumped ecosystems."
"8658858500;7402836869;7403717185;37025898200;7401513327;","Algorithm development of temperature and humidity profile retrievals for long-term HIRS observations",2016,"10.3390/rs8040280","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971643802&doi=10.3390%2frs8040280&partnerID=40&md5=663faeb41b4af1f92407080f92efe298","A project for deriving temperature and humidity profiles from High-resolution Infrared Radiation Sounder (HIRS) observations is underway to build a long-term dataset for climate applications. The retrieval algorithm development of the project includes a neural network retrieval scheme, a two-tiered cloud screening method, and a calibration using radiosonde and Global Positioning System Radio Occultation (GPS RO) measurements. As atmospheric profiles over high surface elevations can differ significantly from those over low elevations, different neural networks are developed for three classifications of surface elevations. The significant impact from the increase of carbon dioxide in the last several decades on HIRS temperature sounding channel measurements is accounted for in the retrieval scheme. The cloud screening method added one more step from the HIRS-only approach by incorporating the Advanced Very High Resolution Radiometer (AVHRR) observations to assess the likelihood of cloudiness in HIRS pixels. Calibrating the retrievals with radiosonde and GPS RO reduces biases in retrieved temperature and humidity. Except for the lowest pressure level which exhibits larger variability, the mean biases are within ±0.3 °C for temperature and within ±0.2 g/kg for specific humidity at standard pressure levels, globally. Overall, the HIRS temperature and specific humidity retrievals closely align with radiosonde and GPS RO observations in providing measurements of the global atmosphere to support other relevant climate dataset development. © 2016 by the authors."
"56443429600;7003786872;","A temporal kernel method to compute effective radiative forcing in CMIP5 transient simulations",2016,"10.1175/JCLI-D-15-0577.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959499752&doi=10.1175%2fJCLI-D-15-0577.1&partnerID=40&md5=49c7e6ee042cca9b2edbf64eb6363b50","Effective radiative forcing (ERF) is calculated as the flux change at the top of the atmosphere after allowing rapid adjustments resulting from a forcing agent, such as greenhouse gases. Rapid adjustments include changes to atmospheric temperature, water vapor, and clouds. Accurate estimates of ERF are necessary in order to understand the drivers of climate change. This work presents a new method of calculating ERF using a kernel derived from the time series of a model variable (e.g., global mean surface temperature) in a model-step change experiment. The top-of-atmosphere (TOA) radiative imbalance has the best noise tolerance for retrieving the ERF of the model variables tested. This temporal kernel method is compared with an energy balance method, which equates ERF to the TOA radiative imbalance plus the scaled surface temperature change. Sensitivities and biases of these methods are quantified using output from phase 5 of the the Coupled Model Intercomparison Project (CMIP5). The temporal kernel method is likely more accurate for models in which a linear fit is a poor approximation for the relationship between temperature change and TOA imbalance. The difference between these methods is most apparent in forcing estimates for the representative concentration pathway 8.5 (RCP8.5) scenario. The CMIP5 multimodel mean ERF calculated for large volcanic eruptions is 80% of the adjusted forcing reported by the IPCC Fifth Assessment Report (AR5). This suggests that about 5% more energy has come into the earth system since 1870 than suggested by the IPCC AR5. © 2016 American Meteorological Society."
"7202057166;56442378900;7005729142;7403931916;7101653556;6506385754;","The microphysical properties of small ice particles measured by the Small Ice Detector-3 probe during the MACPEX field campaign",2016,"10.1175/JAS-D-16-0126.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003583798&doi=10.1175%2fJAS-D-16-0126.1&partnerID=40&md5=bb07c7f5bb383cf9580169174c20773f","A reliable understanding of the microphysical properties of ice particles in atmospheric clouds is critical for assessing cloud radiative forcing effects in climate studies. Ice particle microphysical properties such as size, shape, and surface roughness all have substantial effects on the single-scattering characteristics of the particles. A recently developed ice particle probe, the Small Ice Detector-3 (SID-3), measures the two-dimensional near-forward light-scattering patterns of sampled ice particles. These scattering patterns provide a wealth of information for understanding the microphysical and radiative characteristics of ice particles. The SID-3 was operated successfully on 12 aircraft flights during the NASA Midlatitude Airborne Cirrus Properties Experiment (MACPEX) field campaign in April 2011. In this study, SID-3 measurements are used to investigate the frequency of occurrence of a number of ice particle properties observed during MACPEX. Individual scattering patterns (7.5°-23°) are used to infer properties of the observed particles as well as to calculate partial scattering functions (PSFs) for ensembles of particles in the measured size range (~5-100 μm). PSFs are compared to ray-tracing-based phase functions to infer additional properties of the particles. Two quantitative values-halo ratio and steepness ratio-are used to characterize PSFs. The MACPEX dataset suggests that most atmospheric ice particles have rough surfaces or are complex in nature. PSFs calculated for particles that were characterized as having smooth surfaces also appeared to more closely resemble rough crystal PSFs. PSFs measured with SID-3 compare well with those calculated for droxtals with rough surfaces. © 2016 American Meteorological Society."
"9239331500;56009810800;7007068469;7005084110;56421663700;7101844867;","The pan-canadian high resolution (2.5 km) deterministic prediction system",2016,"10.1175/WAF-D-16-0035.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85002926168&doi=10.1175%2fWAF-D-16-0035.1&partnerID=40&md5=c196f47592978e0dded3a31cda2b917a","Since November 2014, the Meteorological Services of Canada (MSC) has been running a real-time numerical weather prediction system that provides deterministic forecasts on a regional domain with a 2.5-km horizontal grid spacing covering a large portion of Canada using the Global Environmental Multiscale (GEM) forecast model. This system, referred to as the High Resolution Deterministic Prediction System (HRDPS), is currently downscaled from MSC's operational 10-km GEM-based regional system but uses initial surface fields from a high-resolution (2.5 km) land data assimilation system coupled to the HRDPS and initial hydrometeor fields from the forecast of a 2.5-km cycle, which reduces the spinup time for clouds and precipitation. Forecast runs of 48 h are provided four times daily. The HRDPS was tested and compared to the operational 10-km system. Model runs from the two systems were evaluated against surface observations for common weather elements (temperature, humidity, winds, and precipitation), fractional cloud cover, and also against upper-air soundings, all using standard metrics. Although the predictions of some fields were degraded in some specific regions, the HRDPS generally outperformed the operational system for a majority of the scores. The evaluation illustrates the added value of the 2.5-km model and the potential for improved numerical guidance for the prediction of high-impact weather. © 2016 American Meteorological Society."
"57212215393;7004247643;","Reductions in midlatitude upwelling-favorable winds implied by weaker large-scale Pliocene SST gradients",2016,"10.1002/2015PA002806","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958743455&doi=10.1002%2f2015PA002806&partnerID=40&md5=bef2b3738dfa7d2c61eab0baa8209fc3","The early-to-mid Pliocene (3-5.3 Ma) is the most recent geologic period of significant global warmth. Proxy records of Pliocene sea surface temperature (SST) indicate significant and still unexplained warm anomalies of 3°C-9°C in midlatitude eastern boundary currents, where present-day cool temperatures are maintained by wind-driven upwelling. Here we quantify the effect of large-scale Pliocene-like SST patterns on the surface wind stress around the California, Humboldt, Canary, and Benguela midlatitude coastal upwelling sites. A high-resolution atmosphere model forced with Pliocene SST simulates changes in surface winds that imply reductions of 10% to 50% in both coastal upwelling, driven by alongshore wind stress, and offshore upwelling driven by wind stress curl. These changes result primarily from a reduced meridional temperature gradient which weakens the subtropical highs, and a reduction in zonal land-sea temperature contrast which weakens geostrophic alongshore winds. These results suggest that Pliocene coastal warm anomalies may result in part from atmospheric circulation changes which reduce upwelling intensity. The coastal wind stress and offshore wind stress curl are shown to respond differently to incremental changes in SST, topography, and land surface anomalies. Significant decreases in simulated cloud fraction within the subtropical highs suggest that a weaker land-sea temperature contrast could be maintained by cloud radiative feedbacks. ©2015. American Geophysical Union. All Rights Reserved."
"55683455800;21735369200;7202542344;56498085300;6504688501;","Longitudinal asymmetric trends of tropical cold-point tropopause temperature and their link to strengthened walker circulation",2016,"10.1175/JCLI-D-15-0851.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995480806&doi=10.1175%2fJCLI-D-15-0851.1&partnerID=40&md5=521a73a6d98ece7e173725065f2ea365","The zonal structure of trends in the tropical tropopause layer during 1979-2014 is investigated by using reanalysis datasets and chemistry-climate model simulations. The analysis herein reveals that the tropical cold-point tropopause temperature (CPTT) trends during 1979-2014 are zonally asymmetric; that is, over the tropical central and eastern Pacific (CEP; 20°S-20°N, 160°E-100°W), the CPTT shows an increasing trend of 0.22 K decade-1, whereas over the rest of the tropical regions (non-CEP regions) the CPTT shows a decreasing trend of -0.08 K decade-1. Model simulations suggest that this zonal asymmetry in the tropical CPTT trends can be partly attributed to Walker circulation (WC) changes induced by zonally asymmetric changes of the sea surface temperatures (SSTs). The increasing (decreasing) SSTs over the western Pacific (CEP) result in a larger zonal gradient in sea level pressure over the tropical Pacific and intensified surface easterlies. The increased pressure gradient leads to enhanced convection over the Indo-Pacific warm pool and weakened convection over the CEP, facilitating a stronger WC. The downward branch of the intensified WC induces a dynamical warming over the CEP and the upward branch of the intensified WC induces a dynamical cooling over the non-CEP regions below 150 hPa. The significant warming in the upper troposphere and lower stratosphere (UTLS) caused by the WC descending and wave activity changes in the UTLS over the CEP shifts the cold-point tropopause height to a higher level, while the radiative effects of greenhouse gases, ozone, and water vapor changes in the UTLS make less important contributions to the trend of the tropical CPTT than SST changes. © 2016 American Meteorological Society."
"36623311400;6603268269;7006270084;6603156461;57193213111;","A three-dimensional sectional representation of aerosol mixing state for simulating optical properties and cloud condensation nuclei",2016,"10.1002/2015JD024323","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85021156278&doi=10.1002%2f2015JD024323&partnerID=40&md5=1305ff5b9fb8dd4ff62bce39d0a52321","Light absorption by black carbon (BC) particles emitted from fossil fuel combustion depends on their size and how thickly they are coated with nonrefractory species such as ammonium, sulfate, nitrate, organics, and water. The cloud condensation nuclei (CCN) activation behavior of a particle depends on its dry size and the hygroscopicities of all the individual species mixed together. It is therefore necessary to represent both size and mixing state of aerosols to reliably predict their climate-relevant properties in atmospheric models. Here we describe and evaluate a novel sectional framework in the Model for Simulating Aerosol Interactions and Chemistry (box model), referred to as MOSAIC-mix, that represents the mixing state by resolving aerosol dry size (Ddry), BC dry mass fraction (WBC), and hygroscopicity (k). Using 10 idealized urban plume scenarios in which different types of aerosols evolve over 24 h under a range of atmospherically relevant conditions, we examine errors in CCN concentrations and optical properties with respect to the level of detail of the aerosol mixing state representation. We find that a small number of WBC and k bins can achieve significant reductions in the errors and propose a configuration with 24 Ddry bins, 2 WBC bins, and 2 k bins that give average errors of about 5% or less in CCN concentrations and optical properties, 3-4 times lower than those from size-only resolved (i.e., internally mixed) simulations. These results suggest that MOSAIC-mix is suitable for use in regional and global models to examine the effects of mixing state on aerosol-radiation-cloud feedbacks. © 2016. American Geophysical Union. All Rights Reserved."
"57194466927;","Power and water resources of arid landscapes",2016,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-85020307540&partnerID=40&md5=2c9fcb9fd912184626b0fb1dca881899","Why the transmission lines of electric infrastructure are so important compared to the network of water supply? How can we restore the natural balance? If cyberspace did not exist without electricity, humanity could not survive without water. It is possible to take advantage of using electric grid for helping improve water resources. Transmission towers' structure with an additional structural reinforcement could provide support to a network of artificial clouds made of light galvanized steel bars and strings, nebulizers system and silver iodide canyons. Under these clouds there are closed and open water reservoirs with shade balls depending on topography, climate and soil conditions and they are connected from mountains to the city. Electric lines are much like water pipes. In the case of transmission lines, the higher the voltage, the more electricity that can be transmitted, just like a wide water pipe can carry a larger volume of water. Electrical transmission lines operate at high voltages and carry large amounts of electricity over long distances. New water networks would make use of topography, soil permeability and existing infrastructure. These micro-clouds are also important to reduce fire risk, one of the consequences of droughts. Nature's endorsement of tensegrity structures are efficient because per unit mass, spider fibber is the strongest natural fibber and these structures are transferrable from nano-to mega scale. This is a great challenge to develop scientific procedures to create smart tensegrity structures that can regulate the flux of water resources, as well as thermal, mechanical and electrical energy in a material system by proper choice of material, geometry and controls."
"6507975139;55624169300;57191954932;6507987897;","Differences in the climatological characteristics of precipitation between active and break spells of the Indian summer monsoon",2016,"10.1175/JCLI-D-16-0028.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995471066&doi=10.1175%2fJCLI-D-16-0028.1&partnerID=40&md5=61b89cb4e6bfdf90e8487ba2c4f5f314","Climatological characteristics of precipitation during the active and break spells of the monsoon are studied using 15 years of TRMM measurements. The spatial variation of rain fraction suggests that most of the seasonal rainfall occurs in spells of active monsoon over India, except for the zones along the east coast. The broader reflectivity distribution at higher altitudes and larger average storm height during active spells indicate the high prevalence of deep systems during this spell. The spatial distribution of the occurrence and fraction of different types of rain exhibits large variability from land to ocean and between the spells. The higher occurrence and fraction of stratiform rain during the active spell, particularly over the core monsoon zone, is due to the prevalence of organized mesoscale systems with large stratiform portions. The break spells are characterized by higher occurrence of shallow rain and larger fraction of convective rain. While an evening peak is observed over land during the break spell, the phase of the diurnal cycle exhibits large spatial variability during the active spell. The rainfall peaks from late night to midnight in southeastern India and in the morning near the foothills of the Himalayas during the active spell. The diurnal and semidiurnal components together explain more than 90% of total variance over many of the zones during both spells. The observed differences in precipitation between the spells are discussed in light of the differences in synoptic- and mesoscale mechanisms responsible for the production of precipitation. © 2016 American Meteorological Society."
"55476786400;57199196724;56567463100;55359403600;13411085200;7005140533;","Satellite-based estimation of temporally resolved dust radiative forcing in snow cover",2016,"10.1175/JHM-D-15-0150.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983738958&doi=10.1175%2fJHM-D-15-0150.1&partnerID=40&md5=0c5a880f2b59987ca6120d92f1d9c525","Runoff from mountain snowpack is an important freshwater supply for many parts of the world. The deposition of aeolian dust on snow decreases snow albedo and increases the absorption of solar irradiance. This absorption accelerates melting, impacting the regional hydrological cycle in terms of timing and magnitude of runoff. The Moderate Resolution Imaging Spectroradiometer (MODIS) Dust Radiative Forcing in Snow (MODDRFS) satellite product allows estimation of the instantaneous (at time of satellite overpass) surface radiative forcing caused by dust. While such snapshots are useful, energy balance modeling requires temporally resolved radiative forcing to represent energy fluxes to the snowpack, as modulated primarily by varying cloud cover. Here, the instantaneous MODDRFS estimate is used as a tie point to calculate temporally resolved surface radiative forcing. Dust radiative forcing scenarios were considered for 1) clear-sky conditions and 2) all-sky conditions using satellite-based cloud observations. Comparisons against in situ stations in the Rocky Mountains show that accounting for the temporally resolved all-sky solar irradiance via satellite retrievals yields a more representative time series of dust radiative effects compared to the clear-sky assumption. The modeled impact of dust on enhanced snowmelt was found to be significant, accounting for nearly 50% of the total melt at the more contaminated station sites. The algorithm is applicable to regional basins worldwide, bearing relevance to both climate process research and the operational management of water resources. © 2016 American Meteorological Society."
"55823037600;50461182000;56966011200;16686078100;","Satellite-based shortwave aerosol radiative forcing of dust storm over the Arabian Sea",2016,"10.1002/asl.597","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84955191490&doi=10.1002%2fasl.597&partnerID=40&md5=e6cf9c0704838dc13b79c0132ded5cb8","Dust storm events over the Arabian Sea (AS) have been detected using Moderate Resolution Imaging Spectroradiometer (MODIS) data. Shortwave Aerosol Radiative Forcing (SWARF) due to dust storm is estimated using synchronous observation of Clouds and Earth's Energy System (CERES) and MODIS aerosol optical depth (AOD). Study established a relationship between them as SWARF=-39.12×AOD-16.53 (0.4≤ AOD≤4.0) with r2=0.96. The developed relation can be used for quick, independent estimation of instantaneous SWARF for dust storm over the AS. The relationship can be used to explore the possible effect of dust on climate modulation in this region. © 2016 Royal Meteorological Society."
"16644246500;7003648299;7102567936;","Role of radiative-convective feedbacks in spontaneous tropical cyclogenesis in idealized numerical simulations",2016,"10.1175/JAS-D-15-0380.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977469568&doi=10.1175%2fJAS-D-15-0380.1&partnerID=40&md5=b1efa66c01fb3d3c94d940efd79e0b9e","The authors perform 3D cloud-resolving simulations of radiative-convective equilibrium (RCE) in a rotating framework, with interactive radiation and surface fluxes and fixed sea surface temperature. A tropical cyclone is allowed to develop spontaneously from a homogeneous environment, rather than initializing the circulation with a weak vortex or moist bubble (as is often done in numerical simulations of tropical cyclones). The resulting tropical cyclogenesis is compared to the self-aggregation of convection that occurs in nonrotating RCE simulations. The feedbacks leading to cyclogenesis are quantified using a variance budget equation for the column-integrated frozen moist static energy. In the initial development of a broad circulation, feedbacks involving longwave radiation and surface enthalpy fluxes dominate, which is similar to the initial phase of nonrotating self-aggregation. Mechanism denial experiments are also performed to determine the extent to which the radiative feedbacks that are essential to nonrotating self-aggregation are important for tropical cyclogenesis. Results show that radiative feedbacks aid cyclogenesis but are not strictly necessary. © 2016 American Meteorological Society."
"57196510591;35740099400;7403573190;55821966900;55360542200;6701725792;15829933800;8513912900;8247122100;","An overview of coupled gcm biases in the tropics",2016,"10.1142/9789814696623_0008","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85025085674&doi=10.1142%2f9789814696623_0008&partnerID=40&md5=eaeef2990660fe6a5a71e5a029399d62","This article examines the performance of complex numerical climate models with respect to several aspects of mean tropical climate and its variability. While substantial progress has been made since the early days of climate modeling, many challenges remain. A problem common to most coupled ocean-Atmosphere general circulation models (GCMs) is the cold sea surface temperature (SST) bias in the tropics. Despite this cold SST bias GCMs tend to produce too much precipitation over the tropical oceans, particularly south of the equator. Due to the close link between convection and surface winds, the precipitation biases in GCMs are also accompanied by surface wind biases. Particularly on the equator this strongly affects the simulated ocean currents and vertical temperature stratification. Precipitation biases over land surfaces likely contribute to biases over the equatorial oceans through their influence on the Walker circulation. This influence is particularly strong for the Atlantic basin, where GCMs typically overpredict precipitation over tropical South America and underpredict it over tropical Africa. Despite cold SST biases over much of the tropical oceans, warm SST biases dominate in the southeastern tropical Pacific and Atlantic. These warm biases appear to be due to a combination of surface wind biases (both on the equator and locally), excessive shortwave solar radiation due to insufficient low-level cloud, and weak oceanic stratification reducing the cooling effect of upwelling. The failure to capture the equatorial thermocline (the sharp temperature gradient separating the deep ocean from the warm surface layer) is also an important error source in coupled GCMs.. © 2016 World Scientific Publishing Co. Pte. Ltd."
"55605094800;7202296460;56158429100;37462539100;35096936000;57055441500;57056109900;","Changes in glacier extent and surface elevations in the Depuchangdake region of northwestern Tibet, China",2016,"10.1016/j.yqres.2015.12.005","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958729741&doi=10.1016%2fj.yqres.2015.12.005&partnerID=40&md5=a6732b812ea877ff0eb33d42d5c2aa6c","Remote sensing data, including those from Landsat Thematic Mapper/Enhanced Thematic Mapper Plus (TM/ETM+), the Shuttle Radar Topography Mission Digital Elevation Model (SRTM4.1 DEM), and the Geoscience Laser Altimeter System Ice, Cloud, and Land Elevation Satellite (Glas/ICESat), show that from 1991 to 2013 the glacier area in the Depuchangdake region of northwestern Tibet decreased from 409 to 393 km2, an overall loss of 16 km2, or 3.9% of the entire 1991 glacial area. The mean glacier-thinning rate was -0.40 ± 0.16 m equivalent height of water per year (w.e./yr), equating to a glacier mass balance of -0.16 ± 0.07 km3 w.e./yr. Total mass loss from 2003 to 2009 was -1.13 ± 0.46 km3. Glacier retreat likely reflects increases in annual total radiation, annual positive degree days, and maximum temperature, with concurrent increases in precipitation insufficient to replenish glacial mass loss. The rate of glacier retreat in Depuchangdake is less than that for Himalayan glaciers in Indian monsoon-dominated areas, but greater than that for Karakoram glaciers in mid-latitude westerly-dominated areas. Glacier type, climate zone, and climate change all impact on the differing degrees of long-term regional glacial change rate; however, special glacier distribution forms can sometimes lead to exceptional circumstances. © 2015 University of Washington."
"55836759700;7405763496;","Comparison of simulated precipitation over East Asia in two regional models with hydrostatic and nonhydrostatic dynamical cores",2016,"10.1175/MWR-D-15-0428.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994171976&doi=10.1175%2fMWR-D-15-0428.1&partnerID=40&md5=cd6a2a54cc5fabf31699fb5873a2d290","This study examines the characteristics of a nonhydrostatic dynamical core compared to a corresponding hydrostatic dynamical core in the Regional Model Program (RMP) of the Global/Regional Integrated Model system (GRIMs), a spectral model for regional forecasts, focusing on simulated precipitation over Korea. This kind of comparison is also executed in the Weather Research and Forecasting (WRF) finite-difference model with the same physics package used in the RMP. Overall, it is found that the nonhydrostatic dynamical core experiment accurately reproduces the heavy rainfall near Seoul, South Korea, on a 3-km grid, relative to the results from the hydrostatic dynamical core in both models. However, the characteristics of nonhydrostatic effects on the simulated precipitation differ between the RMP and WRF Model. The RMP with the nonhydrostatic dynamical core improves the local maximum, which is exaggerated in the hydrostatic simulation. The hydrostatic simulation of the WRF Model displaces the major precipitation area toward the mountainous region along the east coast of the peninsula, which is shifted into the observed area in the nonhydrostatic simulation. In the simulation of a summer monsoonal rainfall, these nonhydrostatic effects are negligible in the RMP, but the simulated monsoonal rainfall is still influenced by the dynamical core in the WRF Model even at a 27-km grid spacing. One of the reasons for the smaller dynamical core effect in the RMP seems to be the relatively strong horizontal diffusion, resulting in a smaller grid size of the hydrostatic limit. © 2016 American Meteorological Society."
"36921601500;56458221800;55479763800;57210833956;7102178955;","Lagrangian transport simulations of volcanic sulfur dioxide emissions: Impact of meteorological data products",2016,"10.1002/2015JD023749","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84968724474&doi=10.1002%2f2015JD023749&partnerID=40&md5=7376299e7514f193c97d7400c76d33fd","Sulfur dioxide (SO2) emissions from strong volcanic eruptions are an important natural cause for climate variations. We applied our new Lagrangian transport model Massive-Parallel Trajectory Calculations to perform simulations for three case studies of volcanic eruption events. The case studies cover the eruptions of Grímsvötn, Iceland, Puyehue-Cordón Caulle, Chile, and Nabro, Eritrea, in May and June 2011. We used SO2 observations of the Atmospheric Infrared Sounder (AIRS/Aqua) and a backward trajectory approach to initialize the simulations. Besides validation of the new model, the main goal of our study was a comparison of simulations with different meteorological data products. We considered three reanalyses, i.e., ERA-Interim, Modern-Era Retrospective Analysis for Research and Applications (MERRA), and National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) Reanalysis Project as well as the European Centre for Medium-Range Weather Forecasts (ECMWF) operational analysis. Qualitatively, the SO2 distributions from the simulations compare well not only with the AIRS data but also with Cloud-Aerosol Lidar with Orthogonal Polarization and Michelson Interferometer for Passive Atmospheric Sounding aerosol observations. Transport deviations and the critical success index (CSI) are analyzed to evaluate the simulations quantitatively. During the first 5 or 10 days after the eruptions we found the best performance for the ECMWF analysis (CSI range of 0.25-0.31), followed by ERA-Interim (0.25-0.29), MERRA (0.23-0.27), and NCAR/NCEP (0.21-0.23). High temporal and spatial resolution of the meteorological data does lead to improved performance of Lagrangian transport simulations of volcanic emissions in the upper troposphere and lower stratosphere. © 2016. American Geophysical Union. All rights reserved."
"36459918800;57202410843;34876674300;57190818469;","Comparing and combining remotely sensed land surface temperature products for improved hydrological applications",2016,"10.3390/rs8020162","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962504529&doi=10.3390%2frs8020162&partnerID=40&md5=42ee39bcb002eb7a58fdc977e95c0729","Land surface temperature (LST) is an important variable that provides a valuable connection between the energy and water budget and is strongly linked to land surface hydrology. Space-borne remote sensing provides a consistent means for regularly observing LST using thermal infrared (TIR) and passive microwave observations each with unique strengths and weaknesses. The spatial resolution of TIR based LST observations is around 1 km, a major advantage when compared to passive microwave observations (around 10 km). However, a major advantage of passive microwaves is their cloud penetrating capability making them all-weather sensors whereas TIR observations are routinely masked under the presence of clouds and aerosols. In this study, a relatively simple combination approach that benefits from the cloud penetrating capacity of passive microwave sensors was proposed. In the first step, TIR and passive microwave LST products were compared over Australia for both anomalies and raw timeseries. A very high agreement was shown over the vast majority of the country with R2 typically ranging from 0.50 to 0.75 for the anomalies and from 0.80 to 1.00 for the raw timeseries. Then, the scalability of the passive microwave based LST product was examined and a pixel based merging approach through linear scaling was proposed. The individual and merged LST products were further compared against independent LST from the re-analysis model outputs. This comparison revealed that the TIR based LST product agrees best with the re-analysis data (R2 0.26 for anomalies and R2 0.76 for raw data), followed by the passive microwave LST product (R2 0.16 for anomalies and R2 0.66 for raw data) and the combined LST product (R2 0.18 for anomalies and R2 0.62 for raw data). It should be noted that the drop in performance comes with an increased revisit frequency of approximately 20% compared to the revised frequency of the TIR alone. Additionally, this comparison against re-analysis data was subdivided over Australia's major climate zones and revealed that the relative agreement between the individual and combined LST products against the re-analysis data is consistent over these climate zones. These results are also consistent for both the anomalies and the raw time series. Finally, two examples were provided that demonstrate the proposed merging approach including an example for the Hunter Valley floods along Australia's central coast that experienced significant flooding in April 2015. © 2016 by the authors."
"16028575500;36098422200;56448637100;55822471100;23995325300;7004713188;35459245100;7006712143;","The radiative impact of Nordic anthropogenic black carbon",2016,"10.3402/tellusb.v68.27428","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84995644617&doi=10.3402%2ftellusb.v68.27428&partnerID=40&md5=8981717abd2d55490929f116b0dd8cac","This study presents an assessment of the impact of black carbon (BC) regional emissions of four Nordic countries (Denmark, Finland, Norway and Sweden - denoted henceforth as DFNS). The surface concentrations, radiative forcing and BC-in-snow forcing were calculated using ECHAM-HAMMOZ global aerosol-climate model and, where possible, evaluated with field observations. We found that the model is reproducing the BC surface concentrations for most of the measurement sites considered within 1-2 standard deviations, with only few exceptions. The radiative forcing (top of the atmosphere, short-wave, clear and total sky) of BC emitted in DFNS on regional (Nordic and Arctic area separately) and global levels was calculated by removing the anthropogenic emissions from DFNS. The total values for clear sky for the three regions are 16.2±1.4, 2.9±0.28 and 0.04±0.022mW/m2, respectively. The presence of clouds enhanced the BC radiative forcing. The forcing caused by BC deposited on snow is roughly equal to the direct radiative forcing of airborne BC (17.3±3.34mW/m2 over DFNS, 4.2±0.77mW/m2 over the Arctic and 0.042±0.012mW/m2 globally). © 2016 A. I. Hienola et al."
"6701402110;57133136000;","Greenhouse gas emissions from municipal solid waste management in Vientiane, Lao PDR",2016,"10.1177/0734242X15615425","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958951366&doi=10.1177%2f0734242X15615425&partnerID=40&md5=addc18b6471c6f9269e0e1d4693b8445","Municipal solid waste (MSW) is one of the major environmental problems throughout the world including in Lao PDR. In Vientiane, due to the lack of a collection service, open burning and illegal dumping are commonly practised. This study aims to estimate the greenhouse gas (GHG) emission from the current situation of MSW management (MSWM) in Vientiane and proposes an alternative solution to reduce the GHG emission and environmental impacts. The 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories (IPCC 2006 model) are used for the estimation of GHG emission from landfill and composting. For the estimation of GHG emission from open burning, the Atmospheric Brown Clouds Emission Inventory Manual (ABC EIM) is used. In Vientiane, a total of 232 505 tonnes year-1 of MSW was generated in 2011. Waste generation in Vientiane is 0.69 kg per capita per day, and about 31% of the total MSW generated was directly sent to landfill (71 162 tonnes year-1). The total potential GHG emission from the baseline scenario in 2011 was 110 182 tonnes year-1 CO2-eq, which is 0.15 tonne year-1 CO2-eq per capita. From the three MSWM scenarios proposed, scenario S3, which includes recycling, composting and landfilling, seems to be an effective solution for dealing with MSW in Vientiane with less air pollution, and is environmentally friendly. The total GHG emission in scenario S3 is reduced to 91 920 tonnes year-1 CO2-eq (47% reduction), compared with the S1 scenario where all uncollected waste is diverted to landfill. © The Author(s) 2015."
"57201413383;55424752100;7202089880;56060114900;55584794833;57189501249;35509463200;7003907406;7005165467;","Evaluation of MODIS LAI/FPAR product collection 6. Part 2: Validation and intercomparison",2016,"10.3390/rs8060460","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84974834859&doi=10.3390%2frs8060460&partnerID=40&md5=9e63d61c05d656fb7706e09e9bb496cd","The aim of this paper is to assess the latest version of the MODIS LAI/FPAR product (MOD15A2H), namely Collection 6 (C6). We comprehensively evaluate this product through three approaches: validation with field measurements, intercomparison with other LAI/FPAR products and comparison with climate variables. Comparisons between ground measurements and C6, as well as C5 LAI/FPAR indicate: (1) MODIS LAI is closer to true LAI than effective LAI; (2) the C6 product is considerably better than C5 with RMSE decreasing from 0.80 down to 0.66; (3) both C5 and C6 products overestimate FPAR over sparsely-vegetated areas. Intercomparisons with three existing global LAI/FPAR products (GLASS, CYCLOPES and GEOV1) are carried out at site, continental and global scales. MODIS and GLASS (CYCLOPES and GEOV1) agree better with each other. This is expected because the surface reflectances, from which these products were derived, were obtained from the same instrument. Considering all biome types, the RMSE of LAI (FPAR) derived from any two products ranges between 0.36 (0.05) and 0.56 (0.09). Temporal comparisons over seven sites for the 2001-2004 period indicate that all products properly capture the seasonality in different biomes, except evergreen broadleaf forests, where infrequent observations due to cloud contamination induce unrealistic variations. Thirteen years of C6 LAI, temperature and precipitation time series data are used to assess the degree of correspondence between their variations. The statistically-significant associations between C6 LAI and climate variables indicate that C6 LAI has the potential to provide reliable biophysical information about the land surface when diagnosing climate-driven vegetation responses."
"36494729400;8720083500;55915387400;35191486300;57214357085;55710051100;55730024300;57197788881;","Impact of aerosols on regional climate in southern and northern China during strong/weak east asian summer monsoon years",2016,"10.1002/2015JD023892","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84970005626&doi=10.1002%2f2015JD023892&partnerID=40&md5=f8d3c6615cb99e600dda5fe36929c12f","In this work, we mainly simulate the effects of aerosols on regional climate in southern China (SC) and northern China (NC) and compare the differences of aerosol climatic effects in strong/weak summer monsoon years with a modified regional climate model RegCM4. The results show that the total climatic effects of aerosols cause the decline of averaged air temperature and precipitation of SC and NC in summer. In NC, the strength of temperature drop in strong summer monsoon years is higher than that in weak summer monsoon years, indicating the possible impact from the different changes of radiation, circulation, and precipitation. The decrease of precipitation is more significant in NC in weak summer monsoon years, while it is stronger in SC in strong summer monsoon years due to the difference of aerosol distribution as well as the effects on circulation and cloud microphysics processes. Besides, aerosol effects also cause a decrease of zonal wind at 850 hPa in SC and an increase in NC. The cooling center is more northerly and stronger in strong monsoon year, while it is more southerly and weaker in weak summer monsoon years, which results in the differences of vertical circulation anomaly and meridional wind anomaly at 850 hPa. In weak summer monsoon years, meridional wind at 850 hPa is increased in NC, while it is found to be decreased in SC. In strong summer monsoon years, meridional winds at 850 hPa in both NC and SC are weakened. However, the decrease in SC is much more distinct and clear. © 2016. American Geophysical Union. All Rights Reserved."
"56135196400;7403872687;7401526171;7005052907;6507378331;","A deep neural network modeling framework to reduce bias in satellite precipitation products",2016,"10.1175/JHM-D-15-0075.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84961392473&doi=10.1175%2fJHM-D-15-0075.1&partnerID=40&md5=3fe822f55a1058a64c9d4d6448cc4ad6","Despite the advantage of global coverage at high spatiotemporal resolutions, satellite remotely sensed precipitation estimates still suffer from insufficient accuracy that needs to be improved for weather, climate, and hydrologic applications. This paper presents a framework of a deep neural network (DNN) that improves the accuracy of satellite precipitation products, focusing on reducing the bias and false alarms. The state-of-the-art deep learning techniques developed in the area of machine learning specialize in extracting structural information from a massive amount of image data, which fits nicely into the task of retrieving precipitation data from satellite cloud images. Stacked denoising autoencoder (SDAE), a widely used DNN, is applied to perform bias correction of satellite precipitation products. A case study is conducted on the Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks Cloud Classification System (PERSIANN-CCS) with spatial resolution of 0.08° × 0.08° over the central United States, where SDAE is used to process satellite cloud imagery to extract information over a window of 15 × 15 pixels. In the study, the summer of 2012 (June-August) and the winter of 2012/13 (December-February) serve as the training periods, while the same seasons of the following year (summer of 2013 and winter of 2013/14) are used for validation purposes. To demonstrate the effectiveness of the methodology outside the study area, three more regions are selected for additional validation. Significant improvements are achieved in both rain/no-rain (R/NR) detection and precipitation rate quantification: the results make 33% and 43% corrections on false alarm pixels and 98% and 78% bias reductions in precipitation rates over the validation periods of the summer and winter seasons, respectively. © 2016 American Meteorological Society."
"36538539800;57195938097;55612831900;34876658200;","Sensitivity of simulated chemical concentrations and aerosol-meteorology interactions to aerosol treatments and biogenic organic emissions in WRF/Chem",2016,"10.1002/2016JD024882","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029386857&doi=10.1002%2f2016JD024882&partnerID=40&md5=86be630c322a13fe3dd3f816f0de694c","Coupled air quality and climate models can predict aerosol concentrations and properties, as well as aerosol direct and indirect effects that depend on aerosol chemistry and microphysics treatments. In this study, Weather Research and Forecasting with Chemistry (WRF/Chem) simulations are conducted over continental U.S. (CONUS) for January and July 2001 with the same gas-phase mechanism (CB05) but three aerosol modules (Modal Aerosol Dynamics Model for Europe/Secondary Organic Aerosol Model (MADE/ SORGAM),Model for Simulating Aerosol Interactions and Chemistry (MOSAIC), andModel of Aerosol Dynamics, Reaction, Ionization and Dissolution (MADRID)) to examine the impacts of aerosol treatments on predictions of aerosols and their effects on cloud properties and radiation. The simulations with the three aerosol modules give similar domain mean predictions of surface PM2.5 concentrations but exhibit a strong spatial variation in magnitudes with large differences in eastern U.S. Large discrepancies are found in the predicted concentrations of sulfate and organicmatter due to different treatments in secondary inorganic and secondary organic aerosol (SOA) formation. In particular, the nucleation calculation in MADE/SORGAM causes mass buildup of sulfate which results in much higher sulfate concentrations that those predicted by WRF/Chem with the other two aerosol modules. Different PM mass concentrations and size representations lead to differences in the predicted aerosol number concentrations. The above differences in PM concentrations lead to large differences in simulated condensation nuclei (CCN) and cloud properties in both months. The simulated ranges of domain mean are (1.9-14.3) × 109m-3 and (1.4-5.4) × 109m-3 for PM2.5 number concentration, (1.6-3.9) × 108cm-2 and (1.9-3.9) × 108cm-2 for CCN, 102.9-208.2 cm-3 and 143.7-202.2 cm-3 for column cloud droplet number concentration (CDNC), and 4.5-6.4 and 3.6-6.7 for cloud optical depths (COT) in January and July, respectively. The sensitivity simulation for July 2001 using online biogenic emissions increases isoprene concentrations but decreases terpene concentrations, leading to a domain mean increase in O3 (1.5 ppb) and a decrease in biogenic SOA (-0.07 µgm-3) and PM2.5 (-0.2 µgm-3). Anthropogenic emissions contribute to O3, biogenic SOA (BSOA), and PM2.5 concentrations by 38.0%, 44.2%, and 53.6% domain mean and by up to 78.5%, 89.7%, and 96.3%, respectively, indicating that a large fraction of BSOA is controllable through controlling atmospheric oxidant levels in CONUS. Anthropogenic emissions also contribute to a decrease in downward shortwave flux at ground surface (-5.8Wm-2), temperature at 2m (-0.05°C), wind speed at 10m (-0.02ms-1), planetary boundary layer height (-6.6m), and precipitation (-0.08mm), as well as an increase in CCN (+5.7 × 10-7cm-2), in-cloud CDNC (+40.4 cm-3), and COT (+0.6). This work indicates the need for an accurate representation of several aerosol processes such as SOA formation and aerosol-cloud interactions in simulating aerosol direct and indirect effects in the online-coupled models. © 2016. American Geophysical Union. All Rights Reserved."
"57131052900;56786502600;6603476391;","Hydro-climatic variability in southern ecuador reflected by tree-ring oxygen isotopes",2016,"10.3112/erdkunde.2016.01.05","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960481275&doi=10.3112%2ferdkunde.2016.01.05&partnerID=40&md5=2d719ee61e5a1e7577f025462a2dbd7d","Variations of stable oxygen isotopes in tree-ring cellulose are a widely used proxy to reconstruct hydro-climate variability in tropical and subtropical regions. We present the first δ18O chronology from annual tree rings in tropical Cedrela montana trees growing in the mountain rain forest of the Podocarpus National Park (PNP) in southern Ecuador. The more than a century long data record (1885-2011) comes from up to 15 individual trees (1980-2005) and represents the best- replicated isotope tree-ring chronology from the tropics. In comparison with tree-ring width, stable isotope variations show considerably higher correlations between individuals and thus represent a more reliable climate proxy in this very humid environment. High teleconnections to other stable isotope chronologies from the Amazon lowland indicate a high degree of consistency of regional hydro-climate variations. The PNP δ18O record is correlated with seasonal precipitation (January to April, CRU TS 3.21), frequency of wet days, and cloud cover over the Andean Cordillera Real. Spatial correlations indicate that the El Niño-Southern Oscillation (ENSO) has strong impact on tree-ring δ18O variations. Sea Surface Temperatures (SSTs) of the Niño 3.4 region and Niño 4 region, and the Oceanic Niño Index (ONI) show strong positive correlations with Cedrela oxygen isotope ratios, whereas the ENSO precipitation index correlates negatively. The Niño 3.4 and 4 SST influence is stronger after 1960 than before, indicating a shift in the influence of the Pacific Ocean on moisture variations in the Ecuadorian Andes. In the same period, the positive correlation with oxygen isotope signals from Andean glacier ice cores (r=0.2; p&lt;0.05, 1894-1993) increased strongly (r=0.51; p&lt;0.01, 1960-1993). In conclusion, stable oxygen isotope series from tropical tree species can help reconstruct variations in the hydroclimate of the Andean mountains and their surrounding areas. © 2016, Erdkunde. All rights reserved."
"57188924283;","Intermediate bronze age in southern levant (4200-4000 BP) why did four cities in Transjordan survive Urban collapse?",2016,"10.1515/squa-2016-0001","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84964310682&doi=10.1515%2fsqua-2016-0001&partnerID=40&md5=0ff9f0270701bcfcd61c12e52f66caf5","The first urban culture of southern Levant collapsed and the first period of urbanisation of Canaan (Early Bronze Age I-III) terminated at around 4200 yrs BP. The Canaanites abandoned their walled cities, dispersed and underwent pastoralisation. However, the urban centres of southern Canaan were not destroyed. This fact may point to responsibility of the environmental factor and makes influence influence of anthropogenic factors uncertain, along with the most popular Amorite invasion/destruction hypothesis. A tremendous climatic change occurred at that time in many regions, affecting cultures and civilisations of the Ancient Near East and resulting in abandonment of cities, migrations and great civilizational changes. In southern Levant, virtually all cities were left in ruins with a mysterious exception in Transjordan where four cities: Aroer, Ader, Khirbet Iskander and Iktanu survived and existed throughout the period. Most probably when climatic conditions in Cisjordan excluded possibility of urban life, the ones in Transjordan conditions remained unchanged or altered in a very limited scale. It is now clear that after a period with quite humid and warm climate, the precipitation greatly diminished after 4200 yrs BP in a littoral zone of eastern Mediterranean. A part of Transjordan, probably due to presence of the Dead Sea that somehow created conditions that influenced precipitation, remained a climatic niche with decent rainfall that enabled concentration of population in and around big urban centres and continuation of urban civilisation. Warming in a littoral zone changed dew point temperature preventing formations of clouds above western slopes of Judean and Samarian Hills. Moist air, prevented from condensation was transported eastwards where it could reach ascending currents appearing over the Dead Sea. Masses of air with water vapour moving upwards could form rainy clouds in Transjordan. © 2016, Scientific Publishers OWN. All rights reserved."
"55622222800;24177361900;","Importance of latent heating in mesocyclones for the decay of cold air outbreaks: A numerical process study from the pacific sector of the southern ocean",2016,"10.1175/MWR-D-15-0268.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957794534&doi=10.1175%2fMWR-D-15-0268.1&partnerID=40&md5=ae8e4989f86665ef11bec3d2556822fc","In this study the dynamical mechanisms shaping the evolution of a marine cold air outbreak (CAO) that occurred over the Ross, Amundsen, and Bellingshausen Seas in June 2010 are investigated in an isentropic framework. The drainage of cold air from West Antarctica into the interior Ross Sea, its subsequent export, and the formation of a dome of cold air off the sea ice edge are shown to be intimately linked to a lower-tropospheric cyclone, as well as the cyclonic breaking of an upper-level potential vorticity trough. The dome formation is accompanied by an extreme deepening of the boundary layer, whose top reaches to the height of the low-lying tropopause within the trough, potentially allowing for deep stratosphere-troposphere exchange. A crucial finding of this study is that the decay of the CAO is essentially driven by the circulation associated with a train of mesocyclones and the release of latent heat in their warm sectors. Sensitivity experiments with switched off fluxes of sensible and latent heat reveal that the erosion of the CAO air mass depends critically on the moistening by latent heat fluxes, whereby the synergistic effects of sensible heat fluxes and moist processes amplify the erosion. Within the CAO air mass, the erosion is inhibited by cloud-top radiative cooling and the dissolution of clouds by the entrainment of dryer air. These findings potentially have implications for the representation of CAOs in coarse-resolution climate models. © 2016 American Meteorological Society."
"57192300153;6603837254;9636267700;","Effects of urban plume aerosols on a mesoscale convective system",2016,"10.1175/JAS-D-16-0084.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85003678373&doi=10.1175%2fJAS-D-16-0084.1&partnerID=40&md5=6bcc18e331cea49b25ac38e51d23ea96","This study examines the effects of urban aerosols on a mesoscale convective system (MCS) in the central Great Plains with the Weather Research and Forecasting Model coupled with chemistry (WRF-Chem). Urban emissions from Kansas City, Missouri, were scaled by factors of 0.5, 1.0, and 2.0 to investigate the impact of urban aerosol load on MCS propagation and strength. The first half of the storm development is characterized by a stationary front to the north of Kansas City (phase I; 1800 UTC 26 May-0600 UTC 27 May), which develops into a squall line south of the urban area (phase II; 0600-1800 UTC 27 May). During phase I, doubling urban emissions shifts the precipitation accumulation, with enhancement downwind of the storm propagation and suppression upwind. During phase II, a squall line develops in the baseline and doubled emissions scenarios but not when emissions are halved. These changes in MCS propagation and strength are a function of cold pool strength, which is determined by microphysical processes and directly influenced by aerosol load. Overall, changes in urban emissions drive changes in cloud microphysics, which trigger large-scale changes in storm morphology and precipitation patterns. These results show that urban emissions can play an important role in mesoscale weather systems. © 2016 American Meteorological Society."
"55656523500;55738957800;","Effects of Southeastern Pacific sea surface temperature on the double-ITCZ bias in NCAR CESM1",2016,"10.1175/JCLI-D-15-0852.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84994013342&doi=10.1175%2fJCLI-D-15-0852.1&partnerID=40&md5=01debbfa19b9f32d310da729d508c4b5","The double intertropical convergence zone (ITCZ) is a long-standing bias in the climatology of coupled general circulation models (CGCMs). The warm biases in southeastern Pacific (SEP) sea surface temperature (SST) are also evident in many CGCMs. In this study, the role of SEP SST in the double ITCZ is investigated by prescribing the observed SEP SST in the Community Earth System Model, version 1 (CESM1). Both the double ITCZ and dry equator problems are significantly improved with SEP SST prescribed. Both atmospheric and oceanic processes are involved in the improvements. The colder SST over the SEP decreases the precipitation, which enhances the southeasterly winds outside the prescribed SST region, cooling the ocean via increased evaporation. The enhanced descending motion over the SEP strengthens the Walker circulation. The easterly winds over the equatorial Pacific enhance upwelling and shoal the thermocline over the eastern Pacific. The changes of surface wind and wind curl lead to a weaker South Equatorial Countercurrent and stronger South Equatorial Current, preventing the warm water from expanding eastward, thereby improving both the double ITCZ and dry equator. The enhanced Walker circulation also increases the low-level wind convergence and reduces the wind speed in the tropical western Pacific, leading to warmer SST and stronger convection there. The stronger convection in turn leads to more cloud and reduces the incoming solar radiation, cooling the SST. These competing effects between radiative heat flux and latent heat flux make the atmospheric heat flux secondary to the ocean dynamics in the western Pacific warming. © 2016 American Meteorological Society."
"57193882808;","Towards global large eddy simulation: Super-parameterization revisited",2016,"10.2151/jmsj.2016-017","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988382933&doi=10.2151%2fjmsj.2016-017&partnerID=40&md5=2844d8207bea1fe693d2afae738ba2a0","This paper argues that a global large eddy simulation can be achieved through the application of the superparametrization (SP) methodology on massively parallel computers. SP was proposed over 15 years ago to improve the representation of deep convection and accompanying small-scale processes in large-scale models for the weather and climate. The main idea was to embed in all columns of the large-scale model (featuring horizontal grid lengths of the order of 100 km) a two-dimensional (2D) convection-permitting small-scale model with approximately a 1-km horizontal grid length and periodic lateral boundaries. We propose to expand this methodology by applying a high-spatial-resolution three-dimensional (3D) large-eddy simulation (LES) model as the SP model and by embedding it in all columns of a large-scale model with a horizontal grid length in the range of 10 to 50 km. The outer model can apply hydrostatic equations as typical global numerical weather prediction and climate models today and can simulate atmospheric processes down to the mesoscale, including organized convection. Small-scale processes, such as boundary-layer turbulence and convective drafts, can be simulated by embedded nonhydrostatic (e.g., anelastic) LES models. Although significantly more expensive than the traditional SP, SP LES is ideally suited to take advantage of parallel computation because of the minimal communication between LES models when compared to traditional domain-decomposition methodologies in parallel simulation. Moreover, as illustrated through the idealized 2D mock-Hadley cell simulations, LES models can feature different horizontal and vertical grids in various columns of the large-scale model, and thus target dominant cloud regimes in various geographical regions. Such a system allows an unstructured grid simulation with no additional model development. © 2016, Meteorological Society of Japan."
"57110426700;8696069500;7201504886;","Understanding the intermodel spread in global-mean hydrological sensitivity",2016,"10.1175/JCLI-D-15-0351.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957795000&doi=10.1175%2fJCLI-D-15-0351.1&partnerID=40&md5=e7d8b07a3739c08d55f0efcda3e186b8","This paper assesses intermodel spread in the slope of global-mean precipitation change ΔP with respect to surface temperature change. The ambiguous estimates in the literature for this slope are reconciled by analyzing four experiments from phase 5 of CMIP (CMIP5) and considering different definitions of the slope. The smallest intermodel spread (a factor of 1.5 between the highest and lowest estimate) is found when using a definition that disentangles temperature-independent precipitation changes (the adjustments) from the slope of the temperature-dependent precipitation response; here this slope is referred to as the hydrological sensitivity parameter η. The estimates herein show that η is more robust than stated in most previous work. The authors demonstrate that adjustments and η estimated from a steplike quadrupling CO2 experiment serve well to predict DP in a transient CO2 experiment. The magnitude of η is smaller in the coupled ocean- atmosphere quadrupling CO2 experiment than in the noncoupled atmosphere-only experiment. The offset in magnitude due to coupling suggests that intermodel spread may undersample uncertainty. Also assessed are the relative contribution of η, the surface warming, and the adjustment on the spread in ΔP on different time scales. Intermodel variation of both η and the adjustment govern the spread in ΔP in the years immediately after the abrupt forcing change. In equilibrium, the uncertainty in ΔP is dominated by uncertainty in the equilibrium surface temperature response. Akernel analysis reveals that intermodel spread in η is dominated by intermodel spread in tropical lower tropospheric temperature and humidity changes and cloud changes. © 2016 American Meteorological Society."
"55565318800;6602725432;7003811754;","Regional variation in the wet season of northern Australia",2016,"10.1175/MWR-D-16-0133.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85033979285&doi=10.1175%2fMWR-D-16-0133.1&partnerID=40&md5=91efb9b822d2c85f6d2830557f974c21","Variability in the wet season of tropical northern Australia is examined over its main months, November-March, with a focus on zonal differences between the western, central, and eastern domains, which encompass the northern parts of Western Australia, Northern Territory, and Queensland, respectively. The seasonal progression of the wet season is similar across the region, with steadily increasing atmospheric moisture and rainfall into the core months of the monsoon, January and February, decreasing into March. This seasonal progression differs in the eastern domain, where there is an extension of premonsoonal conditions into December, and a delay of the onset of the monsoon until January. An analysis of TRMM precipitation features (PFs) reveals more intense convection during the premonsoon, steadily decreasing in intensity to much shallower convection by March, with a steady increase in the overall number of PFs throughout the wet season. Regionally, the intensity of PFs steadily decreases eastward across northern Australia with significantly weaker, shallower PFs over the eastern domain. Intraseasonal variability associated with the Madden-Julian oscillation (MJO) has a consistent impact on the rainfall and the total number of TRMM PFs across northern Australia, with both increasing and decreasing during the active and suppressed phases, respectively. However, regional variations in the effect of the MJO lead to radically different characteristics of PFs during the suppressed phases; intense convection and thunderstorms become more frequent over the western and central domains, while shallow PFs associated with the warm rain precipitation process increase in number over the eastern domain. © 2016 American Meteorological Society."
"25825715600;6602515941;22236015300;","How dual-polarization radar observations can be used to verify model representation of secondary ice",2016,"10.1002/2016JD025381","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84989339203&doi=10.1002%2f2016JD025381&partnerID=40&md5=8a72a945d40fd902030a51d1f0b9fc9f","In this paper it is discussed how dual-polarization radar observations can be used to verify model representations of secondary ice production. An event where enhanced specific differential phase, Kdp, signatures in snow occur at the altitudes where temperatures lie in the range between −8 and −3∘C is investigated. By combining radar and surface-based precipitation observations it is shown that these dual-polarization radar signatures are most likely caused by ice with concentrations exceeding those expected from primary ice parameterizations. It is also shown that the newly formed ice particles readily aggregate, which may explain why Kdp values seem to be capped at 0.2–0.3∘/km for a C band radar. For the event of interest, multiple high-resolution (1 km) Weather Research and Forecasting (WRF) model simulations are conducted. When the default versions of the Morrison microphysics schemes were used, the simulated number concentration of frozen hydrometeors is much lower than observed and the simulated ice particle concentrations are comparable with values expected from primary ice parameterizations. Higher ice concentrations, which exceed values expected from primary ice parameterizations, were simulated when ad hoc thresholds for rain and cloud water mixing ratio in the Hallett-Mossop part of the Morrison scheme were removed. These results suggest that the parameterization of secondary ice production in operational weather prediction models needs to be revisited and that dual-polarization radar observations, in conjunction with ancillary observations, can be used to verify them. © 2016. American Geophysical Union. All Rights Reserved."
"55807154400;7006432091;","Comparison of observed and simulated spatial patterns of ice microphysical processes in tropical oceanic mesoscale convective systems",2016,"10.1002/2016JD025074","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84982256672&doi=10.1002%2f2016JD025074&partnerID=40&md5=da6aefdd53be3ff1d57ebe29dcc5faa3","To equitably compare the spatial pattern of ice microphysical processes produced by three microphysical parameterizations with each other, observations, and theory, simulations of tropical oceanic mesoscale convective systems (MCSs) in the Weather Research and Forecasting (WRF) model were forced to develop the same mesoscale circulations as observations by assimilating radial velocity data from a Doppler radar. The same general layering of microphysical processes was found in observations and simulations with deposition anywhere above the 0°C level, aggregation at and above the 0°C level, melting at and below the 0°C level, and riming near the 0°C level. Thus, this study is consistent with the layered ice microphysical pattern portrayed in previous conceptual models and indicated by dual-polarization radar data. Spatial variability of riming in the simulations suggests that riming in the midlevel inflow is related to convective-scale vertical velocity perturbations. Finally, this study sheds light on limitations of current generally available bulk microphysical parameterizations. In each parameterization, the layers in which aggregation and riming took place were generally too thick and the frequency of riming was generally too high compared to the observations and theory. Additionally, none of the parameterizations produced similar details in every microphysical spatial pattern. Discrepancies in the patterns of microphysical processes between parameterizations likely factor into creating substantial differences in model reflectivity patterns. It is concluded that improved parameterizations of ice-phase microphysics will be essential to obtain reliable, consistent model simulations of tropical oceanic MCSs. © 2016. American Geophysical Union. All Rights Reserved."
"56487291800;15048845800;57205878599;56589663100;35759808900;56487370400;","Satellite based detection of volcanic SO2 over Pakistan",2016,"10.30955/gnj.001910","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84986296788&doi=10.30955%2fgnj.001910&partnerID=40&md5=f9ff6abc37a5d82e76325b935a0355fc","The present study is carried out to explain the presence of large concentrations of SO2 in atmosphere of Pakistan during June, 2011. Large volcanic eruptions are a major source of greenhouse and trace gases. The eruption of Mount Nabro in June, 2011 injected large amount of SO2 into stratosphere. Nabro volcanic eruption generated a layer of sulfate aerosols, which resided in stratosphere for months. The total amount of SO2 that was injected into the atmosphere was estimated to be 1.3-2.0 Tg. Data products of Global Ozone Monitoring Experiment (GOME-2), Ozone Monitoring Instrument (OMI) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) were used to study SO2 concentrations and plume movement over Pakistan. HYSPLIT backward trajectory model is utilized to study the origin of SO2 plume. The study confirms that SO2 plume originated from Nabro volcanic eruption and caused significant atmospheric perturbations and affected the air quality of Pakistan. SO2 emissions from volcanic eruptions can pose serious hazard to population as well as global climate. © 2016 Global NEST Printed in Greece. All rights reserved."
"36816703000;8437626600;57212611731;57192695511;55452292200;56594783500;","Did the widespread haze pollution over China increase during the last decade? A satellite view from space",2016,"10.1088/1748-9326/11/5/054019","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84984986452&doi=10.1088%2f1748-9326%2f11%2f5%2f054019&partnerID=40&md5=c4f2a057b53ddb55abea2dd25835fea3","Widespread haze layers usually cover China like low clouds, exerting marked influence on air quality and regional climate. With recent Collection 6 MODIS Deep Blue aerosol data in 2000-2015, we analyzed the trends of regional haze pollution and the corresponding influence of atmospheric circulation in China. Satellite observations show that regional haze pollution is mainly concentrated in northern and central China. The annual frequency of regional haze in northern China nearly doubles between 2000 and 2006, increasing from 30-50 to 80-90 days. Though there is a marked decrease in annual frequency during 2007-2009 due to both reduction of anthropogenic emissions and changes of meteorological conditions, regional pollution increases slowly but steadily after 2009, and maintains at a high level of 70-90 days except for the sudden decrease in 2015. Generally, there is a large increase in the number of regional-scale haze events during the last decade. Seasonal frequency of regional haze exhibits distinct spatial and temporal variations. The increasing winter haze events reach a peak in 2014, but decrease strongly in 2015 due partly to synoptic conditions that are favorable for dispersion. Trends of summer regional haze pollution are more sensitive to changes of atmospheric circulation. Our results indicate that the frequency of regional haze events is associated not only with the strength of atmospheric circulation, but also with its direction and position, as well as variations in anthropogenic emissions. © 2016 IOP Publishing Ltd."
"57151771800;57190184992;","Future aerosol reductions and widening of the northern tropical belt",2016,"10.1002/2016JD024803","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978204674&doi=10.1002%2f2016JD024803&partnerID=40&md5=b9b7027900e37afc2d6a4e952bc48150","Observations show that the tropical belt has widened over the past few decades, a phenomenon associated with poleward migration of subtropical dry zones and large-scale atmospheric circulation. Although part of this signal is related to natural climate variability, studies have identified an externally forced contribution primarily associated with greenhouse gases (GHGs) and stratospheric ozone loss. Here we show that the increase in aerosols over the twentieth century has led to contraction of the northern tropical belt, thereby offsetting part of the widening associated with the increase in GHGs. Over the 21st century, however, when aerosol emissions are projected to decrease, the effects of aerosols and GHGs reinforce one another, both contributing to widening of the northern tropical belt. Models that have larger aerosol forcing, by including aerosol indirect effects on cloud albedo and lifetime, yield significantly larger Northern Hemisphere (NH) tropical widening than models with direct aerosol effects only. More targeted simulations show that future reductions in aerosols can drive NH tropical widening as large as greenhouse gases, and idealized simulations show the importance of NH midlatitude aerosol forcing. Mechanistically, the 21st century reduction in aerosols peaks near 40°N, which results in a corresponding maximum increase in surface solar radiation, NH midlatitude tropospheric warming amplification, and a poleward shift in the latitude of maximum baroclinicity, implying a corresponding shift in atmospheric circulation. If models with aerosol indirect effects better represent the real world, then future aerosol changes are likely to be an important-if not dominant-driver of NH tropical belt widening. © 2016. American Geophysical Union. All Rights Reserved."
"6506136441;57205638870;7004479395;7003851845;56734570800;14051743300;7003865921;6701597468;22978151200;10139397300;6603749963;8045690700;56990731400;14059827200;7006270084;7003666669;7003977187;56250250300;12139043600;55717074000;57203053317;7003777747;7006705919;12139310900;11940188700;6506216890;57208121852;55080097400;7202079615;6507308842;30767842400;55317177900;56384704800;","Evaluation of the aerosol vertical distribution in global aerosol models through comparison against CALIOP measurements: AeroCom phase II results",2016,"10.1002/2015JD024639","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978086987&doi=10.1002%2f2015JD024639&partnerID=40&md5=9d55b076d935b66fc4d73eb78c2f93aa","The ability of 11 models in simulating the aerosol vertical distribution from regional to global scales, as part of the second phase of the AeroCom model intercomparison initiative (AeroCom II), is assessed and compared to results of the first phase. The evaluation is performed using a global monthly gridded data set of aerosol extinction profiles built for this purpose from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) Layer Product 3.01. Results over 12 subcontinental regions show that five models improved, whereas three degraded in reproducing the interregional variability in Zα0-6 km, the mean extinction height diagnostic, as computed from the CALIOP aerosol profiles over the 0-6 km altitude range for each studied region and season. While the models’ performance remains highly variable, the simulation of the timing of the Zα0-6 km peak season has also improved for all but two models from AeroCom Phase I to Phase II. The biases in Zα0-6 kmare smaller in all regions except Central Atlantic, East Asia, and North and South Africa. Most of the models now underestimate Zα0-6 km over land, notably in the dust and biomass burning regions in Asia and Africa. At global scale, the AeroCom II models better reproduce the Zα0-6 km latitudinal variability over ocean than over land. Hypotheses for the performance and evolution of the individual models and for the intermodel diversity are discussed. We also provide an analysis of the CALIOP limitations and uncertainties contributing to the differences between the simulations and observations. © 2016. American Geophysical Union. All Rights Reserved."
"56264439900;7201883017;35551859000;7201454345;10439597500;","Development of the GCOM-C global ETindex estimation algorithm",2016,"10.2480/agrmet.D-15-00022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84973594937&doi=10.2480%2fagrmet.D-15-00022&partnerID=40&md5=eab85321dde0b3e7eedd05651df72c59","Freshwater resources management has become a primary global issue. Improved management of agricultural water is important because agriculture is the dominant user of fresh water. Estimation of evapotranspiration (ET) using satellite imagery is regarded as an effective tool for improving agricultural water management. This paper presents the progress made in the development of a global Evapotranspiration-Index (ETindex) estimation algorithm that is applicable to Global Change Observation Mission-Climate (GCOM-C) satellite observation. The algorithm computes an ET-related indicator that is termed the ETindex. The primary input data are thermal observation data from the satellite and near-surface wind speed data from a global climate model. The ETindex is equivalent to the crop coefficient, which has been applied widely for agricultural and irrigation water management around the globe. As a result, the ETindex maps have congruency with traditional agricultural water management methodologies, although the application targets of the ETindex are not limited to irrigation or agriculture. The algorithm estimates the ETindex by analyzing the relative position of actual surface temperature between two extreme surface conditions (wet and dry conditions). Estimation of the wet and dry surface temperatures is a key component of the algorithm. The developed model represents the wet and dry surface temperatures with less than 1℃ bias and less than 6℃ random error in Shenmu, China. The simple structure of the algorithm is designed to process global data with limited computational load. The final product is a 16-day, cloud-free global ETindex map having spatial resolution equal to that of GCOM-C thermal observation. Daily actual ET is estimated from the global ETindex map using local or global weather datasets that include cloudy and rainy days. © 2016, The Society of Agricultural Meteorology of Japan. All rights reserved."
"56075783500;7201392834;6603000896;56501321400;56786512900;56786364600;6506539095;25225396500;","Assessment of satellite rainfall products over the Andean plateau",2016,"10.1016/j.atmosres.2015.07.012.","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84939496319&doi=10.1016%2fj.atmosres.2015.07.012.&partnerID=40&md5=abbc948ee0d601a70fc05772532d2dab","Nine satellite rainfall estimations (SREs) were evaluated for the first time over the South American Andean plateau watershed by comparison with rain gauge data acquired between 2005 and 2007. The comparisons were carried out at the annual, monthly and daily time steps. All SREs reproduce the salient pattern of the annual rain field, with a marked north-south gradient and a lighter east-west gradient. However, the intensity of the gradient differs among SREs: it is well marked in the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis 3B42 (TMPA-3B42), Precipitation Estimation from remotely Sensed Information using Artificial Neural Networks (PERSIANN) and Global Satellite Mapping of Precipitation (GSMaP) products, and it is smoothed out in the Climate prediction center MORPHing (CMORPH) products. Another interesting difference among products is the contrast in rainfall amounts between the water surfaces (Lake Titicaca) and the surrounding land. Some products (TMPA-3B42, PERSIANN and GSMaP) show a contradictory rainfall deficit over Lake Titicaca, which may be due to the emissivity contrast between the lake and the surrounding lands and warm rain cloud processes. An analysis differentiating coastal Lake Titicaca from inland pixels confirmed this trend. The raw or Real Time (RT) products have strong biases over the study region. These biases are strongly positive for PERSIANN (above 90%), moderately positive for TMPA-3B42 (28%), strongly negative for CMORPH (-42%) and moderately negative for GSMaP (-18%). The biases are associated with a deformation of the rain rate frequency distribution: GSMaP underestimates the proportion of rainfall events for all rain rates; CMORPH overestimates the proportion of rain rates below 2mm day-1; and the other products tend to overestimate the proportion of moderate to high rain rates. These biases are greatly reduced by the gauge adjustment in the TMPA-3B42, PERSIANN and CMORPH products, whereas a negative bias becomes positive for GSMaP. TMPA-3B42 Adjusted (Adj) version 7 demonstrates the best overall agreement with gauges in terms of correlation, rain rate distribution and bias. However, PERSIANN-Adj's bias in the southern part of the domain is very low. © 2015 Elsevier B.V.."
"35552595100;55207690500;56797674700;57209481424;16318479700;7801648954;56263897000;","Automated registration of potential locations for solar energy production with Light Detection and Ranging (LiDAR) and small format photogrammetry",2016,"10.1016/j.jclepro.2015.07.117","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84952815702&doi=10.1016%2fj.jclepro.2015.07.117&partnerID=40&md5=d1e0a18cc74d6d2f0a8fa8841d41a764","Energy production and consumption is a key element in future development which is influenced both by the technical possibilities available and by decision makers. Sustainability issues are closely linked in with energy policy, given the desire to increase the proportion of renewable energy. According to the Horizon 2020 climate and energy package, European Union (EU) member countries have to reduce the amount of greenhouse gases they emit by 20%, to increase the proportion of renewable energy to 20% and to improve energy efficiency by 20% by 2020. In this study we aim to assess the opportunities available to exploit solar radiation on roofs with Light Detection And Ranging (LiDAR) and photogrammetry techniques. The surveyed area was in Debrecen, the second largest city in Hungary. An aerial LiDAR survey was conducted with a density of 12 points/m2, over a 7 × 1.8 km wide band. We extracted the building and roof models of the buildings from the point cloud. Furthermore, we applied a low-cost drone (DJI Phantom with a GoPro camera) in a smaller area of the LiDAR survey and also created a 3D model: buildings and roof planes were identified with multiresolution segmentation of the digital surface models (DSM) and orthophoto coverages. Building heights and building geometry were also extracted and validated in field surveys. 50 buildings were chosen for the geodetic survey and the results of the accuracy assessment were extrapolated to other buildings; in addition to this, 100 building heights were measured. We focused primarily on the roofs, as these surfaces offer possible locations for thermal and photovoltaic equipment. We determined the slope and aspect of roof planes and calculated the incoming solar energy according to roof planes before comparing the results of the point cloud processing of LiDAR data and the segmentation of DSMs. Extracted roof geometries showed varying degrees of accuracy: the research proved that LiDAR-based roof-modelling is the best choice in residential areas, but the results of the drone survey did not differ significantly. Generally, both approaches can be applied, because the solar radiation values calculated were similar. The aerial techniques combined with the multiresolution processing demonstrated can provide a valuable tool to estimate potential solar energy. © 2015 Elsevier Ltd. All rights reserved."
"7402971417;55577946400;7203054240;36627352900;7202155374;","Interannual Variation of the Surface Temperature of Tropical Forests from Satellite Observations",2016,"10.1155/2016/4741390","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957100773&doi=10.1155%2f2016%2f4741390&partnerID=40&md5=cb375b47d1c17bdadfb47927981036ee","Land surface temperatures (LSTs) within tropical forests contribute to climate variations. However, observational data are very limited in such regions. This study used passive microwave remote sensing data from the Special Sensor Microwave/Imager (SSM/I) and the Special Sensor Microwave Imager Sounder (SSMIS), providing observations under all weather conditions, to investigate the LST over the Amazon and Congo rainforests. The SSM/I and SSMIS data were collected from 1996 to 2012. The morning and afternoon observations from passive microwave remote sensing facilitate the investigation of the interannual changes of LST anomalies on a diurnal basis. As a result of the variability of cloud cover and the corresponding reduction of solar radiation, the afternoon LST anomalies tend to vary more than the morning LST anomalies. The dominant spatial and temporal patterns for interseasonal variations of the LST anomalies over the tropical rainforest were analyzed. The impacts of droughts and El Niños on this LST were also investigated. Differences between early morning and late afternoon LST anomalies were identified by the remote sensing product, with the morning LST anomalies controlled by humidity (according to comparisons with the National Centers for Environmental Prediction (NCEP) reanalysis data). COpyright © 2016 Huilin Gao et al."
"56708460400;55751665200;34870277200;6505762249;","The impact of revised simplified arakawa-schubert scheme on the simulation of mean and diurnal variability associated with active and break phases of indian summer monsoon using CFSv2",2016,"10.1002/2016JD025393","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983059099&doi=10.1002%2f2016JD025393&partnerID=40&md5=a35b32ab9d34ca7b0c2fb7ab3d03090f","The impact of revised simplified Arakawa-Schubert (RSAS) convective parameterization scheme in Climate Forecast System (CFS) version 2 (CFSv2) on the simulation of active and break phases of Indian summer monsoon (ISM) has been investigated. The results revealed that RSAS showed better fidelity in simulating monsoon features from diurnal to daily scales during active and break periods as compared to SAS simulation. Prominent improvement can be noted in simulating diurnal phase of precipitation in RSAS over central India (CI) and equatorial Indian Ocean (EIO) region during active periods. The spatial distribution of precipitation largely improved in RSAS simulation during active and break episodes. CFSv2 with SAS simulation has noticeable dry bias over CI and wet bias over EIO region which appeared to be largely reduced in RSAS simulation during both phases of the intraseasonal oscillation (ISO). During active periods, RSAS simulates more realistic probability distribution function (PDF) in good agreement with the observation. The relative improvement has been identified in outgoing longwave radiation, monsoon circulations, and vertical velocities in RSAS over SAS simulation. The improvement of rainfall distribution appears to be contributed by proper simulation of convective rainfall in RSAS. CFSv2 with RSAS simulation is able to simulate observed diurnal cycle of rainfall over CI. It correctly reproduces the time of maximum rainfall over CI. It is found that the improved feedback between moisture and convective processes in RSAS may be attributed to its improved simulation. Besides improvement, RSAS could not reproduce proper tropospheric temperature, cloud hydrometeors over ISM domain which shows the scope for future development. © 2016. American Geophysical Union. All Rights Reserved."
"55541291500;7402944490;56049995400;","Dominant modes of interannual variability in Eurasian surface air temperature during boreal spring",2016,"10.1175/JCLI-D-15-0524.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957837599&doi=10.1175%2fJCLI-D-15-0524.1&partnerID=40&md5=810583ccd5cc7d38b3ccf2b5d0b430b6","This study investigates interannual variations of surface air temperature (SAT) overmid- and high latitudes of Eurasia during boreal spring and their association with snow, atmospheric circulation, and sea surface temperature (SST) changes. The leading mode of spring SAT variations is featured by same-sign anomalies over most regions. The secondmode features a tripole anomaly patternwith anomalies over the central part opposite to those over the eastern and western parts of Eurasia. A diagnosis of surface heat flux anomalies suggests that snow change contributes partly to SAT anomalies in several regions mainly by modulating surface shortwave radiation but cannot explain SAT changes in other regions. Atmospheric circulation anomalies play an important role in spring SAT variability via wind-induced heat advection and cloud-induced surface radiation changes. Positive SAT anomalies are associated with anomalous westerly winds fromthe NorthAtlanticOcean or with anomalous anticyclone and southerly winds. Negative SAT anomalies occur in regions of anomalous cyclone and northerly winds. Atmospheric circulation anomalies associated with the first mode have a close relationship to springArctic Oscillation (AO), indicating the impact of theAOon continental-scale spring SAT variations over the mid- and high latitudes of Eurasia. The atmospheric circulation anomalies associated with the secondmode feature a wave pattern over theNorthAtlantic and Eurasia. Such a wave pattern is related to a tripole SST anomaly pattern in the North Atlantic Ocean, signifying the contribution of the North Atlantic Ocean state to the formation of a tripole SAT anomaly pattern over the mid- and high latitudes of Eurasia. © 2016 American Meteorological Society."
"42261008800;55644747600;55578290900;56013128700;","Hourly global solar radiation estimation from MSG-SEVIRI images-case study: Algeria",2016,"10.1108/WJE-06-2016-036","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992562828&doi=10.1108%2fWJE-06-2016-036&partnerID=40&md5=2aadf3ba73da930f966a8cebd72d1360","Purpose - This paper aims to propose an approach based on physical model integration for surface and cloud albedo computation using an approximate form of the atmospheric radiative transfer equation and sun-pixel-satellite. Design/methodology/approach - The data used in this study are global irradiance collected from for various sites in Algeria, and data were obtained from the processing of the high-resolution visible images taken by the Meteosat Second Generation satellite in 2010. Findings - The results suggest that the standard deviation obtained with this method is similar to that obtained with current estimation methods. The hourly and daily correlation coefficients range between 0.95 and 0.97 and between 0.97 and 0.99, respectively. The hourly and daily mean bias errors range between -0.2 and +1.2 per cent and between -0.2 and +1.4 per cent, respectively. The hourly and daily root mean square errors range between 10 and 17 per cent and between 4 and 8 per cent, respectively. Originality/value - This paper developed a new estimating method that derives the hourly global horizontal solar irradiation at a ground level from geostationary satellite data under local climate conditions. © 2016 Emerald Group Publishing Limited."
"57188715329;14042894900;23568239000;55489090900;8385562400;","Vertical profiling of volcanic ash from the 2011 puyehue cordón caulle eruption using IASI",2016,"10.3390/rs8020103","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962596606&doi=10.3390%2frs8020103&partnerID=40&md5=6a41c673bf08a586a1fff14135402f64","Volcanic ash is emitted by most eruptions, sometimes reaching the stratosphere. In addition to its climate effect, ash may have a significant impact on civilian flights. Currently, the horizontal distribution of ash aerosols is quite extensively studied, but not its vertical profile, while of high importance for both applications mentioned. Here, we study the sensitivity of the thermal infrared spectral range to the altitude distribution of volcanic ash, based on similar work that was undertaken on mineral dust. We use measurements by the Infrared Atmospheric Sounding Interferometer (IASI) instruments onboard the MetOp satellite series. The retrieval method that we develop for the ash vertical profile is based on the optimal estimation formalism. This method is applied to study the eruption of the Chilean volcano Puyehue, which started on the 4th of June 2011. The retrieved profiles agree reasonably well with Cloud-Aerosol LiDAR with Orthogonal Polarization (CALIOP) measurements, and our results generally agree with literature studies of the same eruption. The retrieval strategy presented here therefore is very promising for improving our knowledge of the vertical distribution of volcanic ash and obtaining a global 3D ash distribution twice a day. Future improvements of our retrieval strategy are also discussed. © 2016 by the authors."
"39561484400;25926681100;57052558900;6701689811;35577097300;","Meridional gradients in aerosol vertical distribution over Indian Mainland: Observations and model simulations",2016,"10.1016/j.atmosenv.2015.10.066","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84954096449&doi=10.1016%2fj.atmosenv.2015.10.066&partnerID=40&md5=a071fbd1579ca7fa2c6bcda93153d834","Multi-year observations from the network of ground-based observatories (ARFINET), established under the project 'Aerosol Radiative Forcing over India' (ARFI) of Indian Space Research Organization and space-borne lidar 'Cloud Aerosol Lidar with Orthogonal Polarization' (CALIOP) along with simulations from the chemical transport model 'Goddard Chemistry Aerosol Radiation and Transport' (GOCART), are used to characterize the vertical distribution of atmospheric aerosols over the Indian landmass and its spatial structure. While the vertical distribution of aerosol extinction showed higher values close to the surface followed by a gradual decrease at increasing altitudes, a strong meridional increase is observed in the vertical spread of aerosols across the Indian region in all seasons. It emerges that the strong thermal convections cause deepening of the atmospheric boundary layer, which although reduces the aerosol concentration at lower altitudes, enhances the concentration at higher elevations by pumping up more aerosols from below and also helping the lofted particles to reach higher levels in the atmosphere. Aerosol depolarization ratios derived from CALIPSO as well as the GOCART simulations indicate the dominance of mineral dust aerosols during spring and summer and anthropogenic aerosols in winter. During summer monsoon, though heavy rainfall associated with the Indian monsoon removes large amounts of aerosols, the prevailing southwesterly winds advect more marine aerosols over to landmass (from the adjoining oceans) leading to increase in aerosol loading at lower altitudes than in spring. During spring and summer months, aerosol loading is found to be significant, even at altitudes as high as 4 km, and this is proposed to have significant impacts on the regional climate systems such as Indian monsoon. © 2015 Elsevier Ltd."
"57200702127;15755995900;7404829395;56537463000;7006705919;","Toward reconciling the influence of atmospheric aerosols and greenhouse gases on light precipitation changes in Eastern China",2016,"10.1002/2016JD024845","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029369839&doi=10.1002%2f2016JD024845&partnerID=40&md5=eff5bf120c9c82061f710d7fcf8d4206","The attribution of the observed shift in precipitation extremes to different forcing agents represents a critical issue for understanding changes in the hydrological cycle. To compare the effects of aerosols and greenhouse gases on the historical trends of precipitation intensity, we have performed the National Center for Atmospheric Research/Department of Energy Community Atmosphere Model version 5.3 (CAM5) model simulations from 1950 to 2005 driven by observed sea surface temperature and sea ice with and without anthropogenic aerosol forcings. Precipitation rates at every model time step in CAM5 are used to construct precipitation intensity probability distribution functions. We found that the accumulation of greenhouse gases is responsible for the shifts in precipitation intensity on the global scale. However, in Eastern China, dramatic increases in anthropogenic aerosols appear to account for most of the observed light precipitation suppression since 1950s. Under the warming climate induced by greenhouse gases, the enhanced ascending motions primarily lead to the decreases in light precipitation frequency and increases in moderate and heavy precipitation frequencies over the tropics, but there is no significant change in ascending motions in Eastern China only due to the greenhouse gas forcing. By modifying cloud microphysical properties and warm rain processes, aerosol microphysical effects dominate over aerosol radiative effects in determining the historical trend of precipitation intensity distribution in Eastern China. © 2016. American Geophysical Union. All Rights Reserved."
"6602438071;57189710941;55200342600;","Snow extent variability in Lesotho derived from MODIS data (2000-2014)",2016,"10.3390/rs8060448","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84974822755&doi=10.3390%2frs8060448&partnerID=40&md5=ab4a75fe9942dabae52e4c8c406ed0a0","In Lesotho, snow cover is not only highly relevant to the climate system, but also affects socio-economic factors such as water storage for irrigation or hydro-electricity. However, while sound knowledge of annual and inter-annual snow dynamics is strongly required by local stakeholders, in-situ snow information remains limited. In this study, satellite data are used to generate a time series of snow cover and to provide the missing information on a national scale. A snow retrieval method, which is based on MODIS data and considers the concept of a normalized difference snow index (NDSI), has been implemented. Monitoring gaps due to cloud cover are filled by temporal and spatial post-processing. The comparison is based on the use of clear sky reference images from Landsat-TM and ENVISAT-MERIS. While the snow product is considered to be of good quality (mean accuracy: 68%), a slight bias towards snow underestimation is observed. Based on the daily product, a consistent time series of snow cover for Lesotho from 2000-2014 was generated for the first time. Analysis of the time series showed that the high annual variability of snow coverage and the short duration of single snow events require daily monitoring with a gap-filling procedure."
"55577486600;7402146514;56783223600;35758658900;","Retrieval of leaf area index (LAI) and fraction of absorbed photosynthetically active radiation (FAPAR) from VIIRS time-series data",2016,"10.3390/rs8040351","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84971612139&doi=10.3390%2frs8040351&partnerID=40&md5=5a07375f26425babbcd164b5fd6fbcd3","Long-term high-quality global leaf area index (LAI) and fraction of absorbed photosynthetically active radiation (FAPAR) products are urgently needed for the study of global change, climate modeling, and many other problems. As the successor of the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor, the Visible Infrared Imaging Radiometer Suite (VIIRS) will continue to provide global environmental measurements. This paper aims to generate longer time series Global LAnd Surface Satellite (GLASS) LAI and FAPAR products after the era of the MODIS sensor. To ensure spatial and temporal consistencies between GLASS LAI/FAPAR values retrieved from different satellite observations, the GLASS LAI/FAPAR retrieval algorithms were adapted in this study to retrieve LAI and FAPAR values from VIIRS surface reflectance time-series data. After reprocessing of the VIIRS surface reflectance to remove remaining effects of cloud contamination and other factors, a database generated from the GLASS LAI product and the reprocessed VIIRS surface reflectance for all Benchmark Land Multisite Analysis and Intercomparison of Products (BELMANIP) sites was used to train general regression neural networks (GRNNs). The reprocessed VIIRS surface reflectance data from an entire year were entered into the trained GRNNs to estimate the one-year LAI values, which were then used to calculate FAPAR values. A cross-comparison indicates that the LAI and FAPAR values retrieved from VIIRS surface reflectance were generally consistent with the GLASS, MODIS and Geoland2/BioPar version 1 (GEOV1) LAI/FAPAR values in their spatial patterns. The LAI/FAPAR values retrieved from VIIRS surface reflectance achieved good agreement with the GLASS LAI/FAPAR values (R2 = 0.8972 and RMSE = 0.3054; and R2 = 0.9067 and RMSE = 0.0529, respectively). However, validation of the LAI and FAPAR values derived from VIIRS reflectance data is now limited by the scarcity of LAI/FAPAR ground measurements. © 2016 by the authors."
"35552423300;7006253952;35200078000;","Environmental constraints on terrestrial vertebrate behaviour and reproduction in the high Arctic of the Late Cretaceous",2016,"10.1016/j.palaeo.2015.09.041","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949009534&doi=10.1016%2fj.palaeo.2015.09.041&partnerID=40&md5=cd3f246864980fdfc125737e5b892997","Reconstructions of temperature and moisture regimes based on fossil leaves, combined with tree ring studies, detail the light regime, length of the growing season, and summer and winter temperatures of the Late Cretaceous Arctic. Such constraints have important implications for dinosaur feeding and reproductive behaviour, and the capacity to reside year-round in near-polar environments.At the highest palaeolatitudes where dinosaurs have been found (82-85 °N) winter darkness lasted for ∼120 days and the spring and autumn twilight periods for ∼15 days. A mostly cloud and mist-shrouded environment witnessed a mean annual temperature (MAT) of 6-7 °C, a warm month mean temperature (WMMT) of 14.5 ±. 3.1 °C and a cold month mean temperature (CMMT) of -2 ±. 3.9 °C. Growth rings in wood suggest summer temperatures frequently fell below + 10 °C. Winter temperatures as low as -10 °C were likely for short periods. Spring bud break in late February to early March and leaf fall in early October limited the time when fresh food was available in any quantity to not more than 6. months.The diversity of Arctic dinosaur body sizes implies a range of overwintering strategies but year-round residency requires reproduction. Burrowing and enclosed nest building no doubt facilitated overwintering for small animals, but for larger dinosaurs shelter was problematical. No dinosaur egg remains have yet been found as far north as 82° palaeolatitude, but they occur 6° further south in the Early Maastrichtian Kakanaut Formation, Northeastern Russia. Here the winter darkness was shorter (45 days), and the temperature regime warmer (MAT 10 °C, WMMT 19 °C, CMMT + 3 °C). The growing season (temperatures > 10 °C) was ∼6.3 months and fresh food was available in quantity for slightly longer. These summer temperatures constrain the thermal regime of nest environments and suggest sophisticated nest management and possibly brooding strategies for the necessary rapid incubation and hatching before the onset of winter. © 2015 Elsevier B.V."
"56075783500;57201321253;6603000896;56501321400;56786512900;56786364600;6506539095;25225396500;","Assessment of satellite rainfall products over the Andean plateau",2016,"10.1016/j.atmosres.2015.07.012","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85062726067&doi=10.1016%2fj.atmosres.2015.07.012&partnerID=40&md5=b1de22e61f2c6fa1592cfbb837c254d9","Nine satellite rainfall estimations (SREs) were evaluated for the first time over the South American Andean plateau watershed by comparison with rain gauge data acquired between 2005 and 2007. The comparisons were carried out at the annual, monthly and daily time steps. All SREs reproduce the salient pattern of the annual rain field, with a marked north–south gradient and a lighter east–west gradient. However, the intensity of the gradient differs among SREs: it is well marked in the Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis 3B42 (TMPA-3B42), Precipitation Estimation from remotely Sensed Information using Artificial Neural Networks (PERSIANN) and Global Satellite Mapping of Precipitation (GSMaP) products, and it is smoothed out in the Climate prediction center MORPHing (CMORPH) products. Another interesting difference among products is the contrast in rainfall amounts between the water surfaces (Lake Titicaca) and the surrounding land. Some products (TMPA-3B42, PERSIANN and GSMaP) show a contradictory rainfall deficit over Lake Titicaca, which may be due to the emissivity contrast between the lake and the surrounding lands and warm rain cloud processes. An analysis differentiating coastal Lake Titicaca from inland pixels confirmed this trend. The raw or Real Time (RT) products have strong biases over the study region. These biases are strongly positive for PERSIANN (above 90%), moderately positive for TMPA-3B42 (28%), strongly negative for CMORPH (− 42%) and moderately negative for GSMaP (− 18%). The biases are associated with a deformation of the rain rate frequency distribution: GSMaP underestimates the proportion of rainfall events for all rain rates; CMORPH overestimates the proportion of rain rates below 2 mm day − 1 ; and the other products tend to overestimate the proportion of moderate to high rain rates. These biases are greatly reduced by the gauge adjustment in the TMPA-3B42, PERSIANN and CMORPH products, whereas a negative bias becomes positive for GSMaP. TMPA-3B42 Adjusted (Adj) version 7 demonstrates the best overall agreement with gauges in terms of correlation, rain rate distribution and bias. However, PERSIANN-Adj's bias in the southern part of the domain is very low. © 2015 Elsevier B.V."
"7004327525;7101681381;35486904800;","Solar forecasting in a challenging insular context",2016,"10.3390/atmos7020018","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84959515180&doi=10.3390%2fatmos7020018&partnerID=40&md5=f414ca46eb6f090d98f2ac3fdb60a877","This paper aims at assessing the accuracy of different solar forecasting methods in the case of an insular context. Two sites of La Réunion Island, Le Tampon and Saint-Pierre, are chosen to do the benchmarking exercise. Réunion Island is a tropical island with a complex orography where cloud processes are mainly governed by local dynamics. As a consequence, Réunion Island exhibits numerous micro-climates. The two aforementioned sites are quite representative of the challenging character of solar forecasting in the case of a tropical island with complex orography. Hence, although distant from only 10 km, these two sites exhibit very different sky conditions. This work focuses on day-ahead and intra-day solar forecasting. Day-ahead solar forecasts are provided by the European Center for Medium-Range Weather Forecast (ECMWF). This organization maintains and runs the Numerical Weather Prediction (NWP) model named Integrated Forecast System (IFS). In this work, post-processing techniques are applied to refine the output of the IFS model for day-ahead forecasting. Statistical models like a recursive linear model or a nonlinear model such as an artificial neural network are used to produce the intra-day solar forecasts. It is shown that a combination of the IFS model and the neural network model further improves the accuracy of the forecasts. © 2016 by the authors."
"18133397500;57192695511;6603580448;7404291795;57208462871;57204281192;","Satellite-based global volcanic SO2 emissions and sulfate direct radiative forcing during 2005-2012",2016,"10.1002/2015JD023134","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962778866&doi=10.1002%2f2015JD023134&partnerID=40&md5=47e232e989a3f2733a7c7b628e5be5e8","An 8 year volcanic SO2 emission inventory for 2005-2012 is obtained based on satellite measurements of SO2 from OMI (Ozone Monitoring Instrument) and ancillary information from the Global Volcanism Program. It includes contributions from global volcanic eruptions and from eight persistently degassing volcanoes in the tropics. It shows significant differences in the estimate of SO2 amount and injection height for medium to large volcanic eruptions as compared to the counterparts in the existing volcanic SO2 database. Emissions fromNyamuragira (DR Congo) in November 2006 and Grímsvötn (Iceland) in May 2011 that were not included in the Intergovernmental Panel on Climate Change 5 (IPCC) inventory are included here. Using the updated emissions, the volcanic sulfate (SO4 2-) distribution is simulated with the global transport model Goddard Earth Observing System (GEOS)-Chem. The simulated time series of sulfate aerosol optical depth (AOD) above 10 km captures every eruptive volcanic sulfate perturbation with a similar magnitude to that measured by Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). The 8 year average contribution of eruptive SO4 2- to total SO4 2- loading above 10 km is ~10% overmost areas of the Northern Hemisphere, with amaxima of 30% in the tropics where the anthropogenic emissions are relatively smaller. The persistently degassing volcanic SO4 2- in the tropics barely reaches above 10 km, but in the lower atmosphere it is regionallydominant (60%+ in terms ofmass) overHawaii and other oceanic areas northeast of Australia. Although the 7 year average (2005-2011) of eruptive volcanic sulfate forcing of -0.10Wm-2 in this study is comparable to that in the 2013 IPCC report (-0.09Wm-2), significant discrepancies exist for each year. Our simulations also imply that the radiative forcing per unit AOD for volcanic eruptions can vary from -40 to -80Wm-2, much higher than the -25Wm-2 implied in the IPCC calculations. In terms of sulfate forcing efficiency with respect to SO2 emission, eruptive volcanic sulfate is 5 times larger than anthropogenic sulfate. The sulfate forcing efficiency from degassing volcanic sources is close to that of anthropogenic sources. This study highlights the importance of characterizing both volcanicemissionamount and injection altitude aswell as the key role of satellite observations inmaintaining accurate volcanic emissions inventories. © 2016. American Geophysical Union. All Rights Reserved."
"56521954400;55703823500;7401919308;","Seasonal variations in atmospheric responses to oceanic eddies in the Kuroshio Extension",2016,"10.3402/tellusa.v68.31563","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011011323&doi=10.3402%2ftellusa.v68.31563&partnerID=40&md5=ed704b7497067d0d77a2541f8d2e3086","Analyses using high-resolution satellite observations reveal distinct seasonal variations in atmospheric responses to oceanic eddies in the Kuroshio Extension (KE) region, characterised by much stronger surface wind speed and heat flux responses in the cold seasons (winter and spring) than in the warmseasons (summer and autumn). Cloud liquid water and rain rate also display seasonally dependent characteristics, with more deficit (surplus) in winter than in summer over the cold (warm) oceanic eddies. CFSR (Climate Forecast System Reanalysis) data can well reproduce these seasonal variations in surface atmospheric responses to the eddies in the KE region, albeit with much weaker responses in surface wind speed and with stronger responses in latent heat flux in comparison with the results based on satellite observations. In addition, the CFSR data also reveal remarkable seasonal variations in tropospheric responses, with eddy-induced wind speed (vertical velocity) anomalies reaching as high as 900 hPa (800 hPa) in winter, while they only occur near the sea surface in summer. The Weather Research and Forecast (WRF) model is applied to study the seasonal variations in atmospheric responses to idealised oceanic eddies. The model successfully simulates the seasonal variations in atmospheric responses to an idealised warm eddy in terms of wind speed, heat flux, marine atmospheric boundary layer (MABL) height and vertical velocity in both seasons. Both the CFSR data and the model simulations indicate that the seasonal variations in atmospheric responses to oceanic eddies can be attributed to the variations in background atmospheric stability during different seasons. © 2016 J. Ma et al."
"57190584883;15829372900;57190581716;56433673800;37361539800;57190585639;","Appraisal of recent theories to understand cyclogenesis pathways of tropical cyclone madi (2013)",2016,"10.1002/2016JD025188","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84981335284&doi=10.1002%2f2016JD025188&partnerID=40&md5=c976cf91dfee268c38b61087a44929d7","The present study aims to examine the new understanding of cyclogenesis by analyzing the genesis sequence of formation of a very severe cyclonic storm Madi (6-13 December 2013) that occurred over the Bay of Bengal. We have generated a high-resolution (18 km, 6 km, and 2 km) analysis using three-dimensional variational data assimilation technique and Weather Research and Forecasting model. The genesis sequence of Madi cyclone is analyzed using the concepts in the marsupial theory and other theories of tropical cyclone formation. Major results are as follows: The developed analysis is found useful for tracking the movement of westward moving parent disturbance from 15 days prior to the genesis; identifying developed pouch region in the Lagrangian frame of reference; understanding the evolution of the pouch and convection within the pouch region and for the study of intensification inside the pouch region. Also, large-scale priming of environment concurs with the hypotheses of the marsupial theory of tropical cyclogenesis. The analysis of dynamical and thermodynamical processes within the pouch region showed gradual moistening, uplifting of moisture, diabatic heating causing buoyant convection in the vorticity-rich environment followed by vortex tube stretching, development of convection, heavy precipitation, strengthening of lower level convergence, and hence spin-up during a day or two preceding the genesis of Madi cyclone. In general, it is concluded that intensification within pouch region during the cyclogenesis phase followed the marsupial paradigm and bottom-up mechanism. © 2016. American Geophysical Union. All Rights Reserved."
"56233252700;12769875100;55330960300;36895628100;","On the sensitivity of the diurnal cycle in the Amazon to convective intensity",2016,"10.1002/2016JD025039","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978744403&doi=10.1002%2f2016JD025039&partnerID=40&md5=7f9ef96133eca995652d2e748e0c7102","Climate and reanalysis models contain large water and energy budget errors over tropical land related to the misrepresentation of diurnally forced moist convection. Motivated by recent work suggesting that the water and energy budget is influenced by the sensitivity of the convective diurnal cycle to atmospheric state, this study investigates the relationship between convective intensity, the convective diurnal cycle, and atmospheric state in a region of frequent convection-the Amazon. Daily, 3-hourly satellite observations of top of atmosphere (TOA) fluxes from Clouds and the Earth’s Radiant Energy System Ed3a SYN1DEG and precipitation from Tropical Rainfall Measuring Mission 3B42 data sets are collocated with twice daily Integrated Global Radiosonde Archive observations from 2002 to 2012 and hourly flux tower observations. Percentiles of daily minimum outgoing longwave radiation are used to define convective intensity regimes. The results indicate a significant increase in the convective diurnal cycle amplitude with increased convective intensity. The TOA flux diurnal phase exhibits 1-3 h shifts with convective intensity, and precipitation phase is less sensitive. However, the timing of precipitation onset occurs 2-3 h earlier and the duration lasts 3-5 h longer on very convective compared to stable days. While statistically significant changes are found between morning atmospheric state and convective intensity, variations in upper and lower tropospheric humidity exhibit the strongest relationships with convective intensity and diurnal cycle characteristics. Lastly, convective available potential energy (CAPE) is found to vary with convective intensity but does not explain the variations in Amazonian convection, suggesting that a CAPE-based convective parameterization will not capture the observed behavior without incorporating the sensitivity of convection to column humidity. © 2016. American Geophysical Union. All Rights Reserved."
"23502460300;7005231450;7003528814;","Global water vapor trend from 1988 to 2011 and its diurnal asymmetry based on GPS, radiosonde, and microwave satellite measurements",2016,"10.1175/JCLI-D-15-0485.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977599619&doi=10.1175%2fJCLI-D-15-0485.1&partnerID=40&md5=98c18d85f6c994b9702fb6fe7a37b29c","This study analyzes trends in precipitable water (PW) over land and ocean from 1988 to 2011, the PW-surface temperature Ts relationship, and their diurnal asymmetry using homogenized radiosonde data, microwave satellite observations, and ground-based global positioning system (GPS) measurements. It is found that positive PW trends predominate over the globe, with larger magnitudes over ocean than over land. The PW trend is correlated with surface warming spatially over ocean with a pattern correlation coefficient of 0.51. The PW percentage increase rate normalized by Ts expressed as is larger and closer to the rate implied by the Clausius-Clapeyron (C-C) equation over ocean than over land. The 2-hourly GPS PW data show that the PW trend from 1995 to 2011 is larger at night than during daytime. Nighttime PW monthly anomalies correlate positively and significantly with nighttime minimum temperature Tmin at all stations, but this is not true for daytime PW and maximum temperature Tmax. The ratio of relative PW changes with Tmin (dlnPW/dTmin) is larger and closer to the C-C equation's implied value of ~7% K-1 than. This suggests that the relationship between PW and Ts at night is a better indicator of the water vapor feedback than that during daytime, when clouds and other factors also influence Ts. © 2016 American Meteorological Society."
"55350802700;56210720700;37261739700;6701753599;23989889000;16834406100;18134565600;35396858200;8113018100;18438062100;24477694300;57189389471;15080710300;57203776263;7005891596;6603178707;6602356428;16308514000;","Airborne characterization of subsaturated aerosol hygroscopicity and dry refractive index from the surface to 6.5km during the SEAC4RS campaign",2016,"10.1002/2015JD024498","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84969981541&doi=10.1002%2f2015JD024498&partnerID=40&md5=92652ff0dbe538eeb361c99eb8ef6a98","In situ aerosol particle measurements were conducted during 21 NASA DC-8 flights in the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys field campaign over the United States, Canada, Pacific Ocean, and Gulf ofMexico. For the first time, this study reports rapid, size-resolved hygroscopic growth and real refractive index (RI at 532nm) data between the surface and upper troposphere in a variety of air masses including wildfires, agricultural fires, biogenic, marine, and urban outflow. The Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP) quantified size-resolved diameter growth factors (GF =Dp,wet/Dp,dry) that are used to infer the hygroscopicity parameter κ. Thermokinetic simulations were conducted to estimate the impact of partial particle volatilization within the DASH-SP across a range of sampling conditions. Analyses of GF and RI data as a function of air mass origin, dry size, and altitude are reported, in addition to κ values for the inorganic and organic fractions of aerosol. Average RI values are found to be fairly constant (1.52–1.54) for all air mass categories. An algorithm is used to compare size-resolved DASH-SP GF with bulk scattering f(RH= 80%) data obtained froma pair of nephelometers, and the results show that the two can only be reconciled if GF is assumed to decrease with increasing dry size above 400nm (i.e., beyond the upper bound of DASH-SP measurements). Individual case studies illustrate variations of hygroscopicity as a function of dry size, environmental conditions, altitude, and composition. © 2016. American Geophysical Union. All Rights Reserved."
"36538539800;55802355600;56095429600;55624488227;7004444634;7202010686;","Application of WRF/Chem over East Asia: Part I. Model evaluation and intercomparison with MM5/CMAQ",2016,"10.1016/j.atmosenv.2015.07.022","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949624341&doi=10.1016%2fj.atmosenv.2015.07.022&partnerID=40&md5=9f2fb4a6d38a808b974c07e9407124ff","In this work, the application of the online-coupled Weather Research and Forecasting model with chemistry (WRF/Chem) version 3.3.1 is evaluated over East Asia for January, April, July, and October 2005 and compared with results from a previous application of an offline model system, i.e., the Mesoscale Model and Community Multiple Air Quality modeling system (MM5/CMAQ). The evaluation of WRF/Chem is performed using multiple observational datasets from satellites and surface networks in mainland China, Hong Kong, Taiwan, and Japan. WRF/Chem simulates well specific humidity (Q2) and downward longwave and shortwave radiation (GLW and GSW) with normalized mean biases (NMBs) within 24%, but shows moderate to large biases for temperature at 2-m (T2) (NMBs of -9.8% to 75.6%) and precipitation (NMBs of 11.4-92.7%) for some months, and wind speed at 10-m (WS10) (NMBs of 66.5-101%), for all months, indicating some limitations in the YSU planetary boundary layer scheme, the Purdue Lin cloud microphysics, and the Grell-Devenyi ensemble scheme. WRF/Chem can simulate the column abundances of gases reasonably well with NMBs within 30% for most months but moderately to significantly underpredicts the surface concentrations of major species at all sites in nearly all months with NMBs of -72% to -53.8% for CO, -99.4% to -61.7% for NOx, -84.2% to -44.5% for SO2, -63.9% to -25.2% for PM2.5, and -68.9% to 33.3% for PM10, and aerosol optical depth in all months except for October with NMBs of -38.7% to -16.2%. The model significantly overpredicts surface concentrations of O3 at most sites in nearly all months with NMBs of up to 160.3% and NO3- at the Tsinghua site in all months. Possible reasons for large underpredictions include underestimations in the anthropogenic emissions of CO, SO2, and primary aerosol, inappropriate vertical distributions of emissions of SO2 and NO2, uncertainties in upper boundary conditions (e.g., for O3 and CO), missing or inaccurate model representations (e.g., secondary organic aerosol formation, gas/particle partitioning, dust emissions, dry and wet deposition), and inaccurate meteorological fields (e.g., overpredictions in WS10 and precipitation, but underpredictions in T2), as well as the large uncertainties in satellite retrievals (e.g., for column SO2). Comparing to MM5, WRF generally gives worse performance in meteorological predictions, in particular, T2, WS10, GSW, GLW, and cloud fraction in all months, as well as Q2 and precipitation in January and October, due to limitations in the above physics schemes or parameterizations. Comparing to CMAQ, WRF/Chem performs better for surface CO, O3, and PM10 concentrations at most sites in most months, column CO and SO2 abundances, and AOD. It, however, gives poorer performance for surface NOx concentrations at most sites in most months, surface SO2 concentrations at all sites in all months, and column NO2 abundances in January and April. WRF/Chem also gives lower concentrations of most secondary PM and black carbon. Those differences in results are attributed to differences in simulated meteorology, gas-phase chemistry, aerosol thermodynamic and dynamic treatments, dust and sea salt emissions, and wet and dry deposition treatments in both models. © 2015 Elsevier Ltd."
"35739529800;7201784177;","The impact of the Asian summer monsoon circulation on the tropopause",2016,"10.1175/JCLI-D-16-0204.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85000956492&doi=10.1175%2fJCLI-D-16-0204.1&partnerID=40&md5=5402e625eacceda69749a84d4169b086","Previous studies have identified two important features of summertime thermodynamics: 1) a significant correlation between the low-level distribution of equivalent potential temperature θe and the potential temperature θ of the extratropical tropopause and 2) a northwestward shift of the maximum tropopause θ relative to the maximum low-level θe. Here, the authors hypothesize these two features occur because of the Asian monsoon circulation. The hypothesis is examined using a set of idealized prescribed sea surface temperature (SST) aquaplanet simulations. Simulations with a zonally symmetric background climate exhibit a weak moisture-tropopause correlation. A significant correlation and northwestward shift occurs when a zonal wave-1 SST perturbation is introduced in the Northern Hemisphere subtropics. The equivalent zonal-mean subtropical warming does not produce a significant correlation. A mechanism is proposed to explain the moisture-tropopause connection that involves the circulation response to zonally asymmetric surface heating and its impact on the tropopause defined by the 2-potential-vorticity-unit (PVU; 1 PVU = 10-6 K kg-1 m2 s-1) surface. While the circulation response to diabatic heating is well known, here the focus is on the implications for the tropopause. Consistent with previous research, surface heating increases the low-level θe and produces low-level convergence and a cyclonic circulation. The low-level convergence is coupled with upper-level divergence via convection and produces an upper-level anticyclonic circulation consistent with Sverdrup balance. The anticyclonic vorticity lowers the PV northwest of the surface heating via Rossby wave dynamics. The decreased PV leads to a northwestward shift of the 2-PVU surface on fixed pressure levels. The θ value to the northwest of the surface heating is higher, and consequently the maximum tropopause θ increases. © 2016 American Meteorological Society."
"35265542800;7005302245;8591179400;36490812400;","The sensitivity of WRF downscaled precipitation in puerto rico to cumulus parameterization and interior grid nudging",2016,"10.1175/JAMC-D-16-0121.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992724048&doi=10.1175%2fJAMC-D-16-0121.1&partnerID=40&md5=af799d649ad16903ff8ee49c84adf29b","The sensitivity of the precipitation over Puerto Rico that is simulated by the Weather Research and Forecasting (WRF) Model is evaluated using multiple combinations of cumulus parameterization (CP) schemes and interior grid nudging. The NCEP-DOE AMIP-II reanalysis (R-2) is downscaled to 2-km horizontal grid spacing both with convective-permitting simulations (CP active only in the middle and outer domains) and with CP schemes active in all domains. The results generally show lower simulated precipitation amounts than are observed, regardless of WRF configuration, but activating the CP schemes in the inner domain improves the annual cycle, intensity, and placement of rainfall relative to the convective-permitting simulations. Furthermore, the use of interior-grid-nudging techniques in the outer domains improves the placement and intensity of rainfall in the inner domain. Incorporating a CP scheme at convective-permitting scales (<4 km) and grid nudging at non-convective-permitting scales (>4 km) improves the island average correlation of precipitation by 0.05-0.2 and reduces the island average RMSE by up to 40 mm on average over relying on the explicit microphysics at convective-permitting scales with grid nudging. Projected changes in summer precipitation between 2040-42 and 1985-87 using WRF to downscale CCSM4 range from a 2.6-mm average increase to an 81.9-mm average decrease, depending on the choice of CP scheme. The differences are only associated with differences between WRF configurations, which indicates the importance of CP scheme for projected precipitation change as well as historical accuracy. © 2016 American Meteorological Society."
"18134565600;16834406100;35263854800;26039103000;24343173500;6506458269;6701338731;56959669300;6603178707;57209647985;56083852600;6505576518;6603548530;6602356428;35396858200;","Airborne observations of bioaerosol over the Southeast United States using a Wideband Integrated Bioaerosol Sensor",2016,"10.1002/2015JD024669","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978786340&doi=10.1002%2f2015JD024669&partnerID=40&md5=aa72f30f2e04f927697a67744f8d80ae","Biological aerosols represent a diverse subset of particulate matter that is emitted directly to the atmosphere in the form of (but not limited to) bacteria, fungal spores, pollens, viruses, and plant debris. These particles can have local air quality implications, but potentially play a larger climate role by acting as efficient ice nucleating particles (INPs) and cloud condensation nuclei. We have deployed a Wideband Integrated Bioaerosol Sensor on the NASA DC-8 aircraft to (1) quantify boundary layer (BL) variability of fluorescent biological aerosol particle (FBAP) concentrations in the Southeast United States (SEUS), (2) link this variability explicitly to land cover heterogeneity in the region, and (3) examine the vertical profile of bioaerosols in the context of convective vertical redistribution. Flight-averaged FBAP concentrations ranged between 0.1 and 0.4-3 scm--3 (cm -3 at standard temperature and pressure) with relatively homogeneous concentrations throughout the region; croplands showed the highest concentrations in the BL (0.-37 scm -3), and lowest concentrations were associated with evergreen forests (0.24 scm -3). Observed FBAP concentrations are in generally good agreement with model parameterized emission rates for bacteria, and discrepancies are likely the result of fungal spore contributions. Shallow convection in the region is shown to be a relatively efficient lofting mechanism as the vertical transport efficiency of FBAP is at least equal to black carbon aerosol, suggesting that ground-level FBAP survives transport into the free troposphere to be available for INP activation. Comparison of the fraction of coarse-mode particles that were biological (fFBAP) suggested that the SEUS (fFBAP = 8.5%) was a much stronger source of bioaerosols than long-range transport during a Saharan Air Layer (SAL) dust event (fFBAP = 0.17%) or summertime marine emissions in the Gulf of Mexico (fFBAP = 0.73%). © 2016. American Geophysical Union. All Rights Reserved."
"56704589000;57212270042;7006025236;6604054503;57200055610;57203776263;6602221672;16834406100;8359591200;55659925600;14048087800;8261329600;15080710300;6506458269;57212850134;7402711358;6701859178;55501671800;6603775815;6603178707;55683899000;16480965400;18438062100;36616603800;7004643405;57136469800;24477694300;56214091200;7202558218;36661329300;25029309200;7403384594;7006497590;6602356428;7102634471;18134565600;","Agricultural fires in the southeastern U.S. during SEAC4RS: Emissions of trace gases and particles and evolution of ozone, reactive nitrogen, and organic aerosol",2016,"10.1002/2016JD025040","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84977525633&doi=10.1002%2f2016JD025040&partnerID=40&md5=f9f8a9b5de1274d7d7ce5982763c3fbd","Emissions from 15 agricultural fires in the southeastern U.S. were measured from the NASA DC-8 research aircraft during the summer 2013 Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign. This study reports a detailed set of emission factors (EFs) for 25 trace gases and 6 fine particle species. The chemical evolution of the primary emissions in seven plumes was examined in detail for ~1.2 h. A Lagrangian plume cross-section model was used to simulate the evolution of ozone (O3), reactive nitrogen species, and organic aerosol (OA). Observed EFs are generally consistent with previous measurements of crop residue burning, but the fires studied here emitted high amounts of SO2 and fine particles, especially primary OA and chloride. Filter-based measurements of aerosol light absorption implied that brown carbon (BrC) was ubiquitous in the plumes. In aged plumes, rapid production of O3, peroxyacetyl nitrate (PAN), and nitrate was observed with ΔO3/ΔCO, ΔPAN/ΔNOy, and Δnitrate/ΔNOy reaching ~0.1, ~0.3, and ~0.3. For five selected cases, the model reasonably simulated O3 formation but underestimated PAN formation. No significant evolution of OA mass or BrC absorption was observed. However, a consistent increase in oxygen-to-carbon (O/C) ratios of OA indicated that OA oxidation in the agricultural fire plumes was much faster than in urban and forest fire plumes. Finally, total annual SO2, NOx, and CO emissions from agricultural fires in Arkansas, Louisiana, Mississippi, and Missouri were estimated (within a factor of ~2) to be equivalent to ~2% SO2 from coal combustion and ~1% NOx and ~9% CO from mobile sources. © 2016. American Geophysical Union. All Rights Reserved."
"57212901405;57209089003;22136950500;","Influence of post-harvest crop residue fires on surface ozone mixing ratios in the N.W. IGP analyzed using 2years of continuous in situ trace gas measurements",2016,"10.1002/2015JD024308","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962690033&doi=10.1002%2f2015JD024308&partnerID=40&md5=6755f099143e5f5bc7cf35a685bcf7d2","O3, CO, and NOx affect air quality and tropospheric chemistry but factors that control them in the densely populated N.W. Indo-Gangetic Plain (IGP) are poorly understood. This work presents the first simultaneous 2 year long in situ data set acquired from August 2011 to September 2013 at a N.W. IGP site (30.667°N, 76.729°E; 310masl). We investigate the impact of emissions and meteorology on the diel and seasonal variability of O3, CO, and NOx. Regional post-harvest crop residue fires contribute majorly to an enhancement of 19 ppb in hourly averaged ozone concentrations under similar meteorological conditions in summer and 7 ppb under conditions of lower radiation during the post monsoon. d[O3]/dt (from sunrise to daytime O3 maxima) was highest during periods influenced by post-harvest fires in post monsoon season (9.2 ppb h-1) and lowest during monsoon season (4.1 ppb h-1). Analysis of air mass clusters revealed that enhanced chemical formation of O3 and not transport was the driver of the summertime and post monsoon ambient O3 maxima. Despite having high daytime NOx (&gt;12 ppb) and CO (&gt;440 ppb) in winter, average daytime O3 was less than 40 ppb due to reduced photochemistry and fog. Average daytime O3 during the monsoon was less than 45 ppb due to washout of precursors and suppressed photochemistry due to cloud cover. The 8 h ambient air quality O3 standard was violated on 451 days in the period August 2011-September 2013. The results show that substantial mitigation efforts are required to reduce regional O3 pollution in the N.W. IGP. © 2016. American Geophysical Union. All Rights Reserved."
"57164038200;37053536700;","Impact of microphysics schemes in the simulation of cyclone hudhud using WRF-ARW model",2016,,"https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960420419&partnerID=40&md5=f82a8f2b23f214b5f754bcdba36872f0","A Very Severe Cyclonic Strom (VSCS) ""Hudhud"" crossed Andhra coast near Visakhapatnam on 12th October 2014 and caused significant damage to property due to both wind and surge. In the present study, an attempt is made to simulate and test the capability of the state of art Advanced Research Weather Research and Forecasting (WRF-ARW) model in capturing the wind intensity and track of cyclone accurately. The simulation has been carried out using three domains with a horizontal resolution of 27 km for domain 1, 9 km for domain 2 and 3 km for domain 3. Multiple simulations using initial conditions (NCEP FNL) at an interval of 6 hours, same cumulus parameterization and time integration schemes but with different microphysics schemes are carried out. The main source of energy for tropical cyclone is the latent hear release (convective heating) in clouds, which depend on microphysical processes and the released dynamical properties. The objective of the present study is to find out the best microphysics for accurate simulation of intensity and track of tropical cyclone at high model domain resolution towards storm surge studies. The best performance was found for the model integrated for 48 hours starting from 10th October 2014 to 12th October 2014. Simulated features include (track, maximum sustained wind, sea level pressure and rainfall) were compared with IMD best track data and it was observed that simulations with WRF LIN microphysics scheme compare well with observations. Other synoptic features of rainfall was also simulated and discussed in relation to model performance. Overall this study gives emphasis on the studies towards sensitivity analysis of microphysics parameterization using WRF simulations at high model grid resolution (3 km) to imply towards storm surge applications in Bay of Bengal. © Research India Publications."
"57203793097;55790233000;13204740600;57207861695;7006783796;6506234624;","Storm-scale data assimilation and ensemble forecasting with the NSSL Experimental Warn-on-Forecast System. Part II: Combined radar and satellite data experiments",2016,"10.1175/WAF-D-15-0107.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84958964077&doi=10.1175%2fWAF-D-15-0107.1&partnerID=40&md5=222af95d62f9688777db901e45bfbd31","This research represents the second part of a two-part series describing the development of a prototype ensemble data assimilation system for the Warn-on-Forecast (WoF) project known as the NSSL Experimental WoF System for ensembles (NEWS-e). Part I describes the NEWS-e design and results from radar reflectivity and radial velocity data assimilation for six severe weather events occurring during 2013 and 2014. Part II describes the impact of assimilating satellite liquid and ice water path (LWP and IWP, respectively) retrievals from the GOES Imager along with the radar observations. Assimilating LWP and IWP observations may improve thermodynamic conditions at the surface over the storm-scale domain through better analysis of cloud coverage in the model compared to radar-only experiments. These improvements sometimes corresponded to an improved analysis of supercell storms leading to better forecasts of low-level vorticity. This positive impact was most evident for events where convection is not ongoing at the beginning of the radar and satellite data assimilation period. For more complex cases containing significant amounts of ongoing convection, only assimilating clear-sky satellite retrievals in place of clear-air reflectivity resulted in spurious regions of light precipitation compared to the radar-only experiments. The analyzed tornadic storms in these experiments are sometimes too weak and quickly diminished in intensity in the forecasts. The lessons learned as part of these experiments should lead to improved iterations of the NEWS-e system, building on the modestly successful results described here. © 2016 American Meteorological Society."
"36646089600;7410255460;8982105800;","Predictability of tropical cyclone intensity: Scale-dependent forecast error growth in high-resolution stochastic kinetic-energy backscatter ensembles",2016,"10.1002/qj.2626","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957850332&doi=10.1002%2fqj.2626&partnerID=40&md5=4da827007dbe5cd761aef5d3b46818a9","A systematic study of the intrinsic predictability of tropical cyclone (TC) intensity is conducted using a set of cloud-resolving model ensembles of Hurricane Earl (2010). The ensembles are perturbed with a stochastic kinetic-energy backscatter scheme (SKEBS) and started from identical initial conditions. Scale-dependent error growth is investigated by imposing stochastic perturbations with various spatial scales on the TC and its environment. Predictability limits (upper bound) are determined by computing the error magnitude associated with each component of the Fourier-decomposed TC wind fields at forecast times up to 7 days. Three SKEBS ensembles with different perturbation scales are used to investigate the effects of small-scale, mesoscale and large-scale uncertainties on the predictability of TC intensity. In addition, the influence of the environmental flow is investigated by perturbing the lateral boundary conditions. It is found that forecast errors grow rapidly on small scales (azimuthal wave numbers > 20), which saturate within 6-12 h in all four ensembles, regardless of perturbation scale. Errors grow relatively slower on scales corresponding to rain bands (wave numbers 2-5), limiting the predictability of these features to 1-5 days. Earl's mean vortex and the wave number-1 asymmetry are comparatively resistant to error growth and remain predictable for at least 7 days. Forecast uncertainty of the mean vortex and wave number-1 asymmetry is greater in the large-scale perturbation and perturbed lateral boundary condition ensembles. The results from this case indicate that the predictability of the mean vortex and wave number-1 asymmetry is predominately associated with the predictability of the large-scale environment, which is generally much longer than that of convective-scale processes within the TC. © 2016 Royal Meteorological Society."
"55941159700;56604618200;7003786872;","Radiative impacts of the 2011 abrupt drops in water vapor and ozone in the tropical tropopause layer",2016,"10.1175/JCLI-D-15-0167.1","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957836984&doi=10.1175%2fJCLI-D-15-0167.1&partnerID=40&md5=da5c5249a3dd0c1a63dfe9238e7e1b76","An abrupt drop in tropical tropopause layer (TTL) water vapor, similar to that observed in 2000, recently occurred in 2011, and was concurrent with reductions in TTL temperature and ozone. Previous studies have indicated that such large water vapor variability can have significant radiative impacts. This study uses Aura Microwave Limb Sounder observations, the Stratospheric Water Vapor and Ozone Satellite Homogenized dataset, and two radiative transfer models to examine the radiative effects of the observed changes in TTL water vapor and ozone on TTL temperatures and global radiative forcing (RF). The analyses herein suggest that quasi-isentropic poleward propagation of TTL water vapor reductions results in a zonal-mean structure with ''wings'' of extratropical water vapor reductions, which account for about half of the 2011 abrupt drop global radiative impact. RF values associated with the mean water vapor concentrations differences between 2012/13 and 2010/11 are between -0.01 and -0.09 Wm -2, depending upon the altitude above which perturbations are considered. TTL water vapor and ozone variability during this period jointly lead to a transient radiative cooling of ~0.25-0.5K in layers below the tropopause. The 2011 abrupt drop also prolonged the reduction in stratospheric water vapor that followed the 2000 abrupt drop, providing a longer-term radiative forcing of climate. Water vapor concentrations from 2005 to 2013 are lower than those from 1990 to 1999, resulting in a RF between these periods of about -0.045Wm -2, approximately 12% as large as, but of opposite sign to, the concurrent estimated CO2 forcing. © 2016 American Meteorological Society."
"10145101200;56681899900;16033403600;7103311365;16305090000;","Comparison of long-term variability of Sea Surface Temperature in the Arabian Sea and Bay of Bengal",2016,"10.1016/j.rsma.2015.05.004","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956723312&doi=10.1016%2fj.rsma.2015.05.004&partnerID=40&md5=fe2f955e6c5a76f02e5c9192fa13e212","Long-term variability of Sea Surface Temperature (SST) in the Arabian Sea (AS) and Bay of Bengal (BoB) during 1880-2010 is examined using all the available data sets of monthly SST, wind speed, incoming solar radiation, cloud cover, long wave radiation, latent heat flux, net surface heat flux and surface currents. SST time series reveal an upward (increasing) trend (warming) after 1940 in both the basins. Wavelet analyses of the SST time series reveal that AS SST is controlled by semi-annual and annual forcing while the BoB SST is influenced predominantly by annual forcing. The SST responses in both the basins are in phase to the climatic events such as El Niño, La Niña and Indian Ocean Dipole, but a stronger impact is noticed in the AS SST. The climatic events affected the seasonal peaks of SST warming (April-May) and cooling (August-September) in both the basins. Time series of SST anomaly also showed in phase responses to the climatic events and an upward trend from 1960 to 2010 in both the basins. Long-term decreasing trends observed in surface wind speed, latent heat flux and advective process via the weakened surface currents, together with the long-term increasing trend in P - E (Precipitation, P minus Evaporation, E) contributed to the SST warming trend in both the basins. In association with the upward trend in P - E, the Simple Ocean Data Assimilation (SODA) Reanalysis Sea Surface Salinity time series exhibited freshening (a decreasing trend) and enhanced the salinity stratification in the BoB, thus modulated the BoB SST warming. These cumulative processes led to the warmer SSTs in the BoB compared to that in AS. © 2015 Elsevier B.V. All rights reserved."
"56208527200;35773617800;24342542200;6603181723;6701757748;7801573447;","Estimation of snowfall limit for the Kashmir Valley, Indian Himalayas, with TRMM PR Bright Band information",2016,"10.1127/metz/2016/0738","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988844050&doi=10.1127%2fmetz%2f2016%2f0738&partnerID=40&md5=e90238c824b547a316f874660851751a","Knowing the height of the snowfall limit during precipitation events is crucial for better understanding a number of hydro-climatic processes, for instance glacier-climate interactions or runoff from high mountain catchments. However, knowledge on heights of the phase change during precipitation events is limited by the small number of meteorological measurements available at high altitudes, such as the Himalayas. The bright band (BB) of satellite based radar data may be a promising proxy for the snow/rain transition during particular stratiform precipitation events over high mountain regions. The BB is a horizontal layer of stronger radar reflectivity caused by the melting of hydrometeors at the level where solid precipitation turns into rain. Here, we present BB heights detected by the Tropical Rainfall Measuring Mission (TRMM) Precipitation Radar (PR) 2A23 algorithm over a mountainous area. To assess the performance of BB heights, we have compared a 17-year data set of BB estimations of the TRMM PR with radiosonde observations and meteorological station data from Srinagar, Kashmir Valley, India. During March to November, the BB lies mostly about 200 to 800m below the freezing level (FL) recorded by radiosondes. The correlation between BB and FL heights extrapolated from a ground-based station is smaller and depends on the timing of the air temperature measurement - an important finding for applying extrapolation techniques in data sparse regions. Further on, we found a strong seasonal and monthly variability of the BB height, e.g. extending in summer months from about 2700m to almost 6000m asl. Comparison with near surface rain intensity from the TRMM PR product 2A25 indicates that - during intense monsoonal summer precipitation events - the BB height is concentrated between about 3500 and 4000m asl.We can conclude that TRMM PR BB data deliver valuable complementary information for regional or seasonal variability in snow/rain transition in data sparse regions and, further on, BB data from surrounding lowlands could be used to validate extrapolation approaches to assess snowfall limit for mainly stratiform precipitation events where stations at high elevations are missing. © 2016 The authors."
"7201393670;57203057049;57198304064;","Linking spatial inundation indicators and hydrological modelling to improve assessment of inundation extent",2016,"10.1016/j.ecolind.2015.01.033","https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949624874&doi=10.1016%2fj.ecolind.2015.01.033&partnerID=40&md5=2b89727ff6b6f9ef43e6b258f6e2b12c","Environmental water requirements (EWRs), including past inundation regimes, provide useful information for the conservation and management of wetlands systems. However, determining past inundation regimes is difficult as very few wetlands have historical records of water level or flow to determine EWRs. Generally, two approaches have been used to reconstruct wetland inundation regimes; remote sensing or hydrological modelling. Remote sensing methods have applied spectral indices of inundation to multi-temporal archival satellite imagery and developed simple empirical models to link inundation extent to rainfall or stream flow records. Hydrological models use a water balance approach and simple relationships between volume and area based on the wetland bathymetry to derive an inundation regime. While remote sensing approaches can provide a high spatial resolution of information, the temporal resolution is limited to an image every few weeks, and the usability of each image is subject to cloud cover. Hydrological models require some data in the region of interest for calibration, and often the model is not sensitive to the inundation variables of interest when calibrating to the data available. A study is presented where this is the case, where good results are achieved by a hydrological model when compared to downstream flow data, but very different wetland inundation regimes can be simulated. Due to this limitation, the remotely-sensed inundation regime was required as another source of information to calibrate the hydrological model, constraining the parameters involved in the modelled wetland storages. The remote-sensing constrained hydrological model provided greater confidence in the representation of processes occurring in the simulated wetland storages, and hence could be considered appropriate to be applied to a validation time period and for scenario testing. The findings of this research support the combination of remotely sensed indicators of inundation and hydrological modelling to increase confidence in the spatial representation of the dynamics of inundation. Understanding wetland inundation dynamics is critical to the understanding and management of threatened wetland ecosystems. Hence, the methods outlined in paper will ultimately assist in informing better management of wetlands. © 2015 Elsevier Ltd. All rights reserved."
"57203215085;15062311900;6603051853;15046569200;7201659232;34881399900;7003633241;24721471700;7005321781;7007160007;16444433900;36988358200;55894649400;23101118600;35975406100;25230868300;36844740000;15061934800;35790489700;7003406370;","A second horizon scan of biogeography: Golden ages, Midas touches, and the Red Queen",2016,"10.21425/F58429770","https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010220025&doi=10.21425%2fF58429770&partnerID=40&md5=2d7a919853af73e22a7a1c79c26b11a2","Are we entering a new 'Golden Age' of biogeography, with continued development of infrastructure and ideas? We highlight recent developments, and the challenges and opportunities they bring, in light of the snapshot provided by the 7th biennial meeting of the International Biogeography Society (IBS 2015). We summarize themes in and across 15 symposia using narrative analysis and word clouds, which we complement with recent publication trends and 'research fronts'. We find that biogeography is still strongly defined by core sub-disciplines that reflect its origins in botanical, zoological (particularly bird and mammal), and geographic (e.g., island, montane) studies of the 1800s. That core is being enriched by large datasets (e.g. of environmental variables, 'omics', species' occurrences, traits) and new techniques (e.g., advances in genetics, remote sensing, modeling) that promote studies with increasing detail and at increasing scales; disciplinary breadth is being diversified (e.g., by developments in paleobiogeography and microbiology) and integrated through the transfer of approaches and sharing of theory (e.g., spatial modeling and phylogenetics in evolutionary-ecological contexts). Yet some subdisciplines remain on the fringe (e.g., marine biogeography, deep-time paleobiogeography), new horizons and new theory may be overshadowed by popular techniques (e.g., species distribution modelling), and hypotheses, data, and analyses may each be wanting. Trends in publication suggest a shift away from traditional biogeography journals to multidisciplinary or open access journals. Thus, there are currently many opportunities and challenges as biogeography increasingly addresses human impacts on, and stewardship of, the planet (e.g., Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services). As in the past, biogeographers doubtless will continue to be engaged by new data and methods in exploring the nexus between biology and geography for decades into the future. But golden ages come and go, and they need not touch every domain in a discipline nor affect subdisciplines at the same time; moreover, what appears to be a Golden Age may sometimes have an undesirable 'Midas touch'. Contexts within and outwith biogeography-e.g., methods, knowledge, climate, biodiversity, politics-are continually changing, and at times it can be challenging to establish or maintain relevance. In so many races with the Red Queen, we suggest that biogeography will enjoy greatest success if we also increasingly engage with the epistemology of our discipline. © 2016 by the article author(s)."