SMURPHS/ACSIS El Chichon 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 El Chichon aerosol cloud for use in climate model simulations, produced equivalently to the GloSSAC volcanic forcing dataset (Thomason et al., 2018) produced for the 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 main part of the El Chichon period within the GloSSAC volcanic forcing dataset (from Thomason et al., 2018) is generated from combining airborne and ground-based lidar measurements with SAM-II satellite measurements, this SMURPHS/ACSIS dataset is from the ensemble of interactive stratospheric aerosol simulations of the El Chichon aerosol cloud with the UM-UKCA composition-climate model presented in Dhomse et al. (2020).

The main forcing dataset is that from the 3-member mean of the 5Tg @ 24-26km UM-UKCA simulations, matching the "lower SO2 mass, medium-shallow injection height" eruption source parameters realisation within the ISA-MIP HErSEA experiment (Timmreck et al., 2018), found to best match with the majority of 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 1982-1985 quiescent stratospheric aerosol layer (different then from the "average volcanism" background dataset provided for use in the CMIP6 pre-industral 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-GloSSAC 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:

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

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

Thomason, L. W., Ernest, N., Millan, L., Rieger, L., Bourassa, A. Vernier, J.-P., Manney, G., Luo, B. et al. (2018):
"A global space-based stratospheric aerosol climatology: 1979–2016",
Earth Syst. Sci. Data, 10, 469–492, https://doi.org/10.5194/essd-10-469-2018

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