Global Simulations of Aerosol-Cloud-Climate Interactions: Linking the Micro to Global Scale

Aerosol-Cloud-Climate interactions are critically dependent on the representation of cloud microphysical processes, and the microphysical process balance of clouds. For determining precipitation and cloud lifetime, the balance between precipitation production (autoconversion of cloud drops to precipitation) and the subsequent accretion of cloud drops onto precipitation is critical, and affected in different ways by aerosols, and by the co-variance of cloud and rainwater. We analyze these process rates in an advanced global general circulation model with detailed cloud microphysics and aerosol representations. We compare simulations to cloud resolving model studies, as well as new observations of these critical co-variances from high resolution cloud radar measurements. We explore different model formulations that attempt to reproduce observations, and illustrate how changes in the balance of microphysical process rates can alter global estimates of aerosol effects on precipitation and radiation.