SMURPHS/ACSIS Agung volcanic forcing dataset (mapped to UM wavebands) -- from HErSEA ensemble of interactive strat-aerosol GA4 UM-UKCA runs (Dhomse et al., 2020, ACP)

The netCDF file uploaded here is a volcanic forcing dataset for the Agung aerosol cloud for use in climate model simulations, produced equivalently to the CMIP6-AER2D volcanic forcing dataset (Arfeuille et al., 2014; Luo, 2016), generated for use within the post-industrial historical integrations for CMIP6 (Eyring et al., 2016).

The dataset is specific to UKESM (e.g. Sellar et al., 2019), with waveband-averaged extinction, absorption and asymmetry parameter mapped to the SW & LW wavebands within the SOCRATES radiative transfer module (Edwards and Slingo, 1996; Manners et al., 2017).

Whereas the Agung period within the CMIP6-AER2D volcanic forcing dataset (Arfeuille et al., 2014; Luo, 2016) was generated from aerosol microphysics simulations from a 2D model, this SMURPHS/ACSIS dataset is from the ensemble of interactive stratospheric aerosol simulations of the Agung aerosol cloud with the 3D composition-climate model UM-UKCA (see Dhomse et al., 2020).

The main forcing dataset is that from the 3-member mean of the 6Tg @ 20-22km UM-UKCA simulations, matching the "lower SO2 emission, shallow-medium injection height" eruption source parameters realisation within the ISA-MIP HErSEA experiment (Timmreck et al., 2018), found to best match with the benchmark observational datasets compared to in the Dhomse et al. (2020) ACP study.

A control stratospheric aerosol dataset is also provided, based on the corresponding 3 "no-SO2-emission control" integrations from the Dhomse et al. (2020) simulations, then representing the quiescent stratospheric aerosol layer for 1963-1966 (different then from the "average volcanism" background dataset provided for use in the CMIP6 pre-industrial control).

The original 3D-monthly-mean data from the UM-UKCA interactive stratospheric aerosol simulations has been zonally-averaged for this dataset, to match the same structure as for the CMIP6-AER2D dataset.

The latitude resolution of the dataset is 1.25 degrees with 85 hybrid-height vertical levels (see Sellar et al., 2019).

The aerosol optical properties are averaged across the usual 6 UM wavebands in the SW and the 9 wavebands in the LW.

The 1.25 degree resolution matches the ENDGAME N96E horizontal grid for UKESM1 (re-gridded from New Dynamics grid in GA4).

The L85 vertical resolution of the dataset is the same vertical model grid used in the GA4 UM-UKCA N96L85 simulations,
as also required identically for use within UKESM1.

References

Arfeuille, F., Weisenstein, D., Mack, H., Rozanov, E., Peter, T. and Broenimann, S.
"Volcanic forcing for climate modeling: a new microphysics-based data set covering years 1600-present",
Clim. Past, 10, 359-375, 2014, https://doi.org/10.5194/cp-10-359-2014

Dhomse, S. S., Mann, G. W., Antuna Marrero, J.-C., Shallcross, S. E., Chipperfield, M. P., Carslaw, K. S. et al. (2020):
"Evaluating the simulated radiative forcings, aerosol properties, and stratospheric warmings from the 1963 Mt Agung, 1982 El Chichón, and 1991 Mt Pinatubo volcanic aerosol clouds", 
Atmos. Chem. Phys., 20, 13627–13654, https://doi.org/10.5194/acp-20-13627-2020

Edwards, J. M. and Slingo, A. (1996): 
"Studies with a flexible new radiation code. I: Choosing a configuration for a large-scale model",
Quart. J. Roy. Meteor. Soc., 122 , 689–719, https://doi.org/10.1002/qj.49712253107

Eyring, V., Bony, S., Meehl, G. A., Senior, C. A., Stevens, B., Stouffer, R. J. and Taylor, K. E.  (2016):
"Overview of the Coupled Model Intercomparison Project Phase 6 (CMIP6) experimental design and organization",
Geosci. Mod. Dev.,  9, 1937–1958, https://doi.org/10.5194/gmd-9-1937-2016

Luo, B.: Stratospheric aerosol data for use in CMIP6 models, available at: ftp://iacftp.ethz.ch/pub_read/luo/CMIP6/Readme_Data_Description.pdf, 2016.

Manners, J., Edwards, J. M., Hill, P. and Thelen, J.-C. (2017):
"SOCRATES Technical Guide -- Suite Of Community RAdiative Transfer codes based on Edwards and Slingo"
Technical Guide. Met Office, UK. Available at: https://code.metoffice.gov.uk/trac/socrates.

Sellar, A., Jones, C. G., Mulcahy, J. P., Tang, Y., Yool, A., Wiltshire, A., O'Connor, F. M., Stringer, M. et al. (2019):
"UKESM1: Description and Evaluation of the U.K. Earth System Model"
J. Adv. in Modelling Earth Systems, https://doi.org/10.1029/2019MS001739

Timmreck, C. E., Mann, G. W., Aquila, V., Hommel, R., Lee, L. A., Schmidt, A., Bruehl, C., Carn, S. et al. (2018):
"The Interactive Stratospheric Aerosol Model Intercomparison Project (ISA-MIP): motivation and experimental design"
Geosci. Model Dev., 11, 2581-2608, https://doi.org/10.5194/gmd-11-2581-2018