Aerosol Indirect Effects on Warm Clouds in the Grid-Point Atmospheric Model of IAP LASG (GAMIL)

Abstract

Aerosol indirect effects on warm clouds are estimated in the Grid-point Atmospheric Model of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics (IAP LASG) (GAMIL) with a new two-moment cloud microphysics scheme using two different physically-based aerosol activation parameterizations: Abdul-Razzak and Ghan, and Nenes and Seinfeld. The annual global mean changes in shortwave cloud forcing from preindustrial times to present day (a measure of the aerosol indirect effects) estimated from these two parameterizations are remarkably similar: 0.76 W m-2 with the Abdul-Razzak and Ghan parameterization, and 0.78 W m-2 with the Nenes and Seinfeld parameterization. Physically-based parameterizations can provide robust representations of aerosol effects on droplet nucleation, meaning that aerosol activation is no longer the most un-certain factor in modeling aerosol indirect effects.