Winter air temperature and wind speed data from paired open and forest low-cost meteorological stations

The diurnal cycle of both air temperature and wind speed is reflected by considerable differences if open site conditions are compared to forests. This new two-hourly, open dataset covering a high spatial and temporal variability, enables multiple purposes and capabilities due to its diversity and sample size. The dataset provides station pairs, each consisting of one station in the open field and one related station in the forest, located in central Europe, more precisely in southern Germany in the Black Forest (Kinzig; Breg; Brugga) and the Bavarian Alps (Dreisäularbach; Nationalpark Berchtesgaden) as well as the Austrian Alps (Brixenbachtal). Associated meta data specify parameters to characterize the environment and the reference between the paired stations.

The air temperature measurements consist of 128 station pairs from 6 winter seasons and 6 different study sites with a total amount of 173 682 (time steps with availability of open and forest values). The wind speed measurements consist of 64 station pairs from 3 winter seasons and 4 different study sites with a total amount of 115 211. The dataset was initially collected to study the spatio-temporal variability of micrometeorological variables describing the energy balance of the snowpack, but is provided for multiple purposes as examining forest effects on micrometeorological data, validating climate or snow models as well as developing new transfer functions.

Boundary conditions are given below and a comprehensive description of the dataset including analyses and applications follows in the open access article:

Klein, M.; Garvelmann, J.; Förster, K. Revisiting Forest Effects on Winter Air Temperature and Wind Speed—New Open Data and Transfer Functions. Atmosphere 2021, 12, 710. https://doi.org/10.3390/atmos12060710

Meta data
The meta data consists of 12 descriptive characteristics. Pair_ID gives an identification name which includes the year of sampling and the acronym of the study site as well as both stations. The Location parameter is a local description of the study site. Elevation, Exposure and Slope have values for the open and forest stations, while Effective_LAI, Canopy_Openness and Distance_Forest_Edge stands for the forest station. With Distance_Open_Station the distance between both stations is designated. The Exposure parameter is defined counterclockwise as follows: 0° and 360° is north, 90° is west and consequently 180° is south and 270° east. Only a few parameters of Distance_Forest_Edge and Distance_Open_Station are not available. These values are marked with NA.

• Pair_ID: Identification of the station pair [-]
• Location: Local description [-]
• Elevation_Open: Elevation in the open field [m a.s.l.]
• Elevation_Forest: Elevation in the forest [m a.s.l.]
• Exposure_Open: Exposure in the open field counterclockwise (0°/360° = north; 90° = west, etc.)
• Exposure_Forest: Exposure in the forest counterclockwise (0°/360° = north; 90° = west, etc.)
• Slope_Open: Slope in the open field [°]
• Slope_Forest: Slope in the forest [°]
• Effective_LAI: Effective leaf area per ground area [-]
• Canopy_Openness: Openness of the forest canopy [%]
• Distance_Forest_Edge: Distance of the forest station to the closed forest edge [m]
• Distance_Forest_Station: Distance between the paired stations [m]

Time series data
The time series data consists of air temperature datasets and wind speed datasets, which are named after the Pair_ID described above. According to the two-hour intervals, there are 12 measurements per day. The datasets are structured in the same way as follows: The time stamp (Heading: Date), the measurement in the open (Heading: Air_Temp_Open; Wind_Open) and the measurement in the forest (Heading: Air_Temp_Forest; Wind_Forest). Missing values are marked with NA. Remaining information in terms of number of stations, distribution of observations concerning the study sites and winter seasons, the absolute number of available measurements of both stations as well as additional information are listed following.

Air temperature

• 128 station pairs (73 open; 59 forest)
• Kinzig – KIN (9 station pairs/2012; 10 station pairs/2013)
• Breg – BRE (7 station pairs/2012; 9 station pairs/2013; 8 station pairs/2014)
• Brugga – BRU (5 station pairs/2013; 14 station pairs/2014; 5 station pairs/2015)
• Brixenbachtal – BRX (3 station pairs/2015)
• Dreisäulerbach – DSB (7 station pairs/2016; 3 station pairs/2017)
• Nationalpark Berchtesgaden – NPB (8 station pairs/2015; 26 station pairs/2016; 14 station pairs/2017)
• 173 682 total measurements with both values available
• Variables: Date [yyyy-MM-dd hh:mm:ss]; Air_Temp_Open [°C]; Air_Temp_Forest [°C]
• 2 h time interval between measurements
• Indication for missing value: NA
• Additional information: Air temperature values measured at open stations corrected for radiative heating. Near surface wind speed is measured at 2 m above surface.

Wind speed

• 64 station pairs (27 open; 34 forest)
• Brugga – BRU (5 station pairs/2015)
• Brixenbachtal – BRX (3 station pairs/2015)
• Dreisäulerbach – DSB (7 station pairs/2016; 3 station pairs/2017)
• Nationalpark Berchtesgaden – NPB (7 station pairs/2015; 25 station pairs/2016; 14 station pairs/2017)
• 115 211 total measurements with both values available
• Variables: Date [yyyy-MM-dd hh:mm:ss]; Wind_Open [ms^-1]; Wind_Forest [ms^-1]
• 2 h time interval between measurements
• Indication for missing value: NA
• Additional information: Near surface wind speed is measured at 2 m above surface.

Author Contributions
JG led and supervised the field work to collect the data and compiled the dataset. Editing and preparation referring to the publication by JG, MK and KF.

Acknowledgements
The presented data was collected during the following research projects:

“Field Observations and Modelling of Spatial and Temporal Variability of Processes Controlling Basin Runoff during Rain on Snow Events” funded by the German Research Foundation (DFG) and carried out at the Chair of Hydrology (PI Stefan Pohl), University of Freiburg, Germany;

“Alpine water resources research: Observing and modeling the spatio-temporal variability of snow dynamics and water- and energy fluxes” funded by Helmholtz Water Alliance and carried out at the Institute of Meteorology and Climate Research (IMK-IFU, PI Jakob Garvelmann, research group Harald Kunstmann), Karlsruhe Institute of Technology (KIT), Garmisch-Partenkirchen, Germany. Technical infrastructure from TERENO;

“Storylines of Socio-Economic and Climatic drivers for Land use and their hydrological impacts in Alpine Catchments (STELLA)” funded by the Austrian climate and energy fond and carried out at the Institute of Geography (PI Ulrich Strasser), University of Innsbruck, Austria.

Many thanks to Daniel Günther, Franziska Zieger, Michael Warscher and others for assistance in field work and Emil Blattmann and the staff from KIT-Campus Alpin for technical support. At the University of Innsbruck Elisabeth Mair led the field work within the STELLA-project. Furthermore, we would like to thank Nationalpark of Berchtesgaden for supporting the micrometeorological and snow hydrological measurement campaign.