PNNL

Abstract

Aerosol effective radiative forcing critically influences climate projections but remains poorly constrained. Using the Energy Exascale Earth System Model (E3SM) Simple Cloud-Resolving E3SM Atmosphere Model (SCREAM) v1 configuration, we quantify the forcing due to anthropogenic aerosol changes using a simplified prescribed aerosol scheme (SPA) derived from the E3SM v3 model. Nudged simulations at 3 km and 12 km horizontal grid spacings reveal a more negative aerosol forcing than the reference 100-km E3SM v3 model whence the SPA properties are derived. The resulting globally averaged aerosol forcing signal is largely due to aerosol--cloud interactions and exhibits little overall resolution sensitivity. While the default SPA scheme overestimates cloud droplet dependence on aerosols, parameterization adjustments in the activation process reconcile forcing estimates with the reference model. Our results demonstrate the ability to use a prescribed aerosol scheme to hold aerosol forcing to a desired state across resolutions