A01: Aerosol effective radiative forcing in E3SM

Aerosol radiative forcing in E3SM: improvements from aerosol wet removal treatment and parameter tuning

• Yunpeng Shan

• Yunpeng.Shan@pnnl.gov

Yunpeng Shan, Jiwen Fan, E3SMv3 atmosphere development team

Atmosphere

E3SM

Anthropogenic aerosol effective radiative forcing (ERF_aer) is an important metric to quantify aerosol effects on climate in Earth system models. Department of Energy’s Energy Exascale Earth System Model (E3SM) tends to overestimate ERF_aer, direct forcing (ERF_ari), and indirect forcing (ERF_aci), and one important reason is the significantly overestimated aerosol burden and lifetime. The insufficient aerosol wet removal is attributed to the aerosol overestimation. We improved the aerosol wet removal treatments in E3SM and tuned the hygroscopicity of black carbon, leading aerosol burdens well sit within the reference value ranges. Consequently, the ERF_ari significantly decreases to reasonable values and ERF_aci also decreases. Tuning of cloud sensitivity to aerosols and imposing cloud droplet number can further decrease ERF_aci. As a result, the total aerosol forcing and its components have been well within the reference ranges.

Yes

Yunpeng.Shan@pnnl.gov