DOI: 10.5281/zenodo.17466719
title: HiLLA-SAI simulations in UKESM1, CESM2-WACCM and E3SMv3

description: Simulations of High-latitude low-altitude (HiLLA) stratopsheric aerosol injection (SAI) under various injection strategies, carried out in three earth system models: UKESM1, CESM2-WACCM, and E3SMv3. The simulations are in support of the analysis contained in Duffey et al., 2025; The global climate response to High-Latitude Low-Altitude Stratospheric Aerosol Injection (HiLLA-SAI) (forthcoming). In each case, 12Tg SO2 per year is injected into the lower stratosphere, starting in 2035, and causing the climate state to deviate from the background SSP2-4.5 scenario. Two central injection strategies are simulated: HiLLA-13 and HiLLA-15, which have injection at 60°N/S in the local spring (March-June/September-Devember), and at 13 km and 15 km, respectively. These simulatations are 35-years in length. Nine additional 3-year sensitivy simulations vary the injection latitude, longitude, altitude and seasonality. 

See also the analysis code here https://github.com/alistairduffey/HiLLA_MM

Data here does not include all outpus on levels (ozone, geopotential height and SO4 burdens), as these files are too large for practical storage on Zenodo. Contact Alistair Duffey (alistair.duffey.21@ucl.ac.uk) for help locating them. 

For SO4/H2SO4 mass mixing ratios under HiLLA-13 and HiLLA-15 (case 1 and case 4): Zonal mean SO4 burdens are included for CESM2-WACCM, under "SO4 burden/"; data on several defined pressure levels is included for E3SM in "E3SM_HiLLA_Mass_so4.zip"; zonal means for UKESM are in the seperate upload "UKESM1_HiLLA_mass_H2SO4.zip". Note that mass-mixing ratio for UKESM1 includes H2SO4 by mode - nucleation ('nuc'), Aitken (ait), accumulation ('acc'), and course ('cou'). 

Runs are labelled as follows in file naming: 




UKESM1
CESM2-WACCM
E3SMv3
Description


u-dj993
case01
01
HiLLA-13 : 35-year run with injection at 13km, 60°N/S, MAMJ/SOND, 180° longitude


u-dk092
case02
02
Latitude sensitivity: 3-year run with injection at 13km, 70°N/S, MAMJ/SOND, 180° longitude


u-dk163
case03
03
Latitude sensitivity: 3-year run with injection at 13km, 50°N/S, MAMJ/SOND, 180° longitude


u-dm204dn587
case04
04
HiLLA-15 : 35-year run with injection at 15km, 60°N/S, MAMJ/SOND, 180° longitude


u-dk101
case05
05
Altitude sensitivity: 3-year run with injection at 15km, 70°N/S, MAMJ/SOND, 180° longitude


u-dk164
case06
06
Altitude sensitivity: 3-year run with injection at 15km, 50°N/S, MAMJ/SOND, 180° longitude


u-dn605
case07
07
Seasonality sensitivity: 3-year run with injection at 13km, 60°N/S, MAM/SON, 180° longitude


u-dn675
case08
08
Seasonality sensitivity: 3-year run with injection at 13km, 60°N/S, MAMJJ/SONDJ, 180° longitude


u-dn690
case09
09
Seasonality sensitivity: 3-year run with injection at 13km, 60°N/S, FMAMJ/ASOND, 180° longitude


u-dn757
case10
10
Longitude sensitivity: 3-year run with injection at 13km, 60°N/S, MAMJ/SOND, 0° longitude


u-dn758
case11
11
Longitude sensitivity: 3-year run with injection at 15km, 60°N/S, MAMJ/SOND, 0° longitude


-
-
control
SSP2-4.5 reference case - existing CMIP6 simulations are used for comparison in UKESM1 and CESM2-WACCM




 

v1.1 added some additional SO4/H2SO4 data for UKESM1 and E3SM relative to v1.0