Improving aerosol radiative forcing and climate in E3SM: Impacts of new cloud microphysics and improved wet removal treatments

Here, in the context of the E3SM version 3 effort, the predicted particle property (P3) stratiform cloud microphysics scheme and an enhanced deep convection parameterization suite (ZM_plus) are implemented into E3SM. The ZM_plus includes a convective cloud microphysics scheme, a multi-scale coherent structure parameterization for mesoscale convective systems, and a revised cloud base mass flux formulation considering impacts of the large-scale environment.

The P3 scheme improved cloud and radiation particularly over the Northern Hemisphere and the frequency of heavy precipitation over the tropics, and the ZM_plus improved clouds in the tropics. P3 decreases aerosol effective forcing by 0.15 W m-2, while the ZM_plus increases it by 0.27 W m-2, resulting from excessive direct (0.31 W m-2) and indirect forcing (-1.79 W m-2). The excessive aerosol forcings are due to aerosol overestimation associated with insufficient aerosol wet removal.