Geoengineering CCMI experiment

We performed three sets of experiments as part of the Chemistry Climate Model Initiative project: REFC2 , G4SSA and G4SSA-S using the full tropospheric and stratospheric chemistry version of the Community Earth System Model – Community Atmospheric Model 4 (CESM CAM4-chem) with horizontal resolution of 0.9° x 1.25° lat-lon and 26 levels from the surface to about 40 km (3.5 hPa). Each set of experiment has three ensemble members. RCP6.0 is the reference run from 2004 to 2089, and G4SSA and G4SSA-S are two solar radiation management scenarios. G4SSA is G4 Specified Stratospheric Aerosol experiment with 8Tg SO2 injection to the stratosphere per year, described in Tilmes et al., 2013, whereas G4SSA-S is solar reduction geoengineering by imposing a solar irradiance reduction with the same negative radiative forcing at the top of the atmosphere as in G4SSA. Results of these experiments are described in Xia et al., 2017.