Multiscale Modeling of the Indirect Impact of Atmospheric Aerosols on Climate

The goal of the project is to advance knowledge of the indirect aerosol impact through the modification of cloud condensation nuclei (CCN) and ice nuclei (IN). A two-moment bulk warm-rain scheme suitable in representing essential cloud and precipitation processes in high-resolution (large-eddy simulation, LES) models of ice-free clouds has recently been implemented. It is proposed (i) to apply these comprehensive cloud microphysics parameterizations in process-level studies concerning ice-bearing clouds with the emphasis on indirect aerosol effects, and (ii) to use these parameterizations and improved process-level understanding to model indirect effects in the atmospheric general circulation model applying the super-parameterization approach. For (i), previously developed and applied kinematic framework and cloud-resolving models will be utilized. For (ii), the Community Atmospheric Model with embedded SAM as the super-parameterization will be used. Such a modeling system (referred to as Multiscale Modeling Framework, or MMF) was developed and applied in recent studies. Simulations of atmospheric general circulation using MMF with improved SAM will provide more reliable assessment of the indirect effects of atmospheric aerosols on climate.