Aerosol-Cloud Interactions in Acme-MMF Model

By acting as cloud condensation nuclei (CCN) or ice nuclei (IN), aerosol can change the physical properties of cloud/precipitation and thus affect mesoscale convective system (MCS). Previous studies on aerosol effect on MCS were limited to case studies at regional scale through either regional model simulations or field campaign studies. Very few global model studies have been performed at global and climate scales. One of major reasons is that the traditional global climate models (GCMs), including the Accelerated Climate Model for Energy (ACME) model, are unable to simulate the mesoscale because the relevant physics acts over a wide range of spatial-temporal scales. However, the multi-scale model framework (MMF) model (also known as Super-Parameterization, SP), embedding a cloud-resolving model (CRM) within each grid column of a GCM, shows promising results in representing the MCS signals. Here, we couple the MMF model to the ACME to study aerosol effects on cloud/precipitations. We evaluate simulated cloud/precipitation fields from the ACME-MMF model, and examine the anthropogenic aerosol effects on cloud/precipitation by comparing the simulation with present-day aerosol/precursor emissions and the one with pre-industrial aerosol/precursor emissions. We also test the effect of cloud microphysics on cloud/precipitation simulations. We use two different versions of ACME-MMF: one with the CRM of two-moment cloud microphysics and the other with 1-moment microphysics. We thus compare the simulations obtained from these two different versions of ACME-MMF.