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

本地上传的网络通用数据格式（netCDF）文件为适用于气候模式模拟的埃尔奇琼火山（El Chichon）气溶胶云团强迫数据集，其制作标准与为耦合模式比较计划第六阶段（CMIP6）历史积分试验（Eyring等，2016）开发的GloSSAC火山强迫数据集（Thomason等，2018）保持一致。

本数据集专为英国地球系统模型（UKESM）设计（参见Sellar等，2019），将波段平均后的消光系数、吸收系数与不对称参数映射至SOCRATES辐射传输模块内的短波（SW）与长波（LW）波段（Edwards和Slingo，1996；Manners等，2017）。

相较于GloSSAC火山强迫数据集（Thomason等，2018）中埃尔奇琼火山时段的核心数据，其通过整合机载、地基激光雷达（lidar）测量数据与SAM-II卫星测量数据生成；本SMURPHS/ACSIS数据集则源自Dhomse等（2020）中提出的、基于UM-UKCA化学-气候耦合模式对埃尔奇琼火山气溶胶云团开展的交互式平流层气溶胶集合模拟结果。

本核心强迫数据集取自5太克（Tg）喷发量、注入高度24-26km的UM-UKCA模拟结果的3成员平均，匹配交互式平流层气溶胶模式比较计划（ISA-MIP）HErSEA试验（Timmreck等，2018）中“低二氧化硫质量、中浅注入高度”的喷发源参数试验方案，该方案在Dhomse等（2020）发表于《大气化学与物理》（ACP）的研究中，被证实与绝大多数基准观测数据集匹配度最优。

本数据集同时提供平流层气溶胶对照数据集，其基于Dhomse等（2020）模拟中对应的3组“无二氧化硫排放对照”积分试验，代表1982-1985年的静稳平流层气溶胶层（与为CMIP6工业化前对照试验提供的“平均火山活动”背景数据集存在差异）。

本数据集的原始数据取自UM-UKCA交互式平流层气溶胶模拟的三维逐月平均结果，已完成纬向平均处理，以匹配CMIP6-GloSSAC数据集的结构格式。

本数据集的纬度分辨率为1.25°，包含85层混合高度垂直坐标层（参见Sellar等，2019）。

气溶胶光学特性已按UM模式标准的6个短波波段与9个长波波段完成平均。

该1.25°分辨率匹配UKESM1所用的ENDGAME N96E水平网格（由GA4版本的新动力学网格重网格化得到）。

本数据集的L85垂直分辨率与GA4版本UM-UKCA N96L85模拟所用的垂直模式网格完全一致，该配置同样适配UKESM1的运行要求。

参考文献：

1. Dhomse, S. S., Mann, G. W., Antuna Marrero, J.-C., Shallcross, S. E., Chipperfield, M. P., Carslaw, K. S. 等（2020）：《评估1963年阿贡火山、1982年埃尔奇琼火山与1991年皮纳图博火山气溶胶云团的模拟辐射强迫、气溶胶特性及平流层增温》，《大气化学与物理》，20卷，13627–13654页，https://doi.org/10.5194/acp-20-13627-2020

2. Edwards, J. M. 和 Slingo, A.（1996）：《灵活新型辐射代码研究I：为大尺度模式选择配置》，《皇家气象学会季刊》，122卷，689–719页，https://doi.org/10.1002/qj.49712253107

3. Eyring, V., Bony, S., Meehl, G. A., Senior, C. A., Stevens, B., Stouffer, R. J. 和 Taylor, K. E.（2016）：《耦合模式比较计划第六阶段（CMIP6）试验设计与组织概述》，《地球科学模型开发》，9卷，1937–1958页，https://doi.org/10.5194/gmd-9-1937-2016

4. Manners, J., Edwards, J. M., Hill, P. 和 Thelen, J.-C.（2017）：《SOCRATES技术指南——基于Edwards与Slingo开发的社区辐射代码套件》，英国气象局技术报告，可访问：https://code.metoffice.gov.uk/trac/socrates.

5. Sellar, A., Jones, C. G., Mulcahy, J. P., Tang, Y., Yool, A., Wiltshire, A., O'Connor, F. M., Stringer, M. 等（2019）：《UKESM1：英国地球系统模型的描述与评估》，《地球系统建模进展》，https://doi.org/10.1029/2019MS001739

6. Thomason, L. W., Ernest, N., Millan, L., Rieger, L., Bourassa, A., Vernier, J.-P., Manney, G., Luo, B. 等（2018）：《全球星基平流层气溶胶气候学：1979–2016》，《地球系统科学数据》，10卷，469–492页，https://doi.org/10.5194/essd-10-469-2018

7. Timmreck, C. E., Mann, G. W., Aquila, V., Hommel, R., Lee, L. A., Schmidt, A., Bruehl, C., Carn, S. 等（2018）：《交互式平流层气溶胶模式比较计划（ISA-MIP）：研究动机与试验设计》，《地球科学模型开发》，11卷，2581-2608页，https://doi.org/10.5194/gmd-11-2581-2018