Impact of Aerosols on Convective Clouds and Precipitation

Aerosols are a critical factor in the atmospheric hydrological cycle and radiation budget. As a major agent for clouds to form and a significant attenuator of solar radiation, aerosols affect climate in several ways. Current research suggests that aerosols have a major impact on the dynamics, microphysics, and electrification properties of continental mixed-phase convective clouds. In addition, high aerosol concentrations in urban environments could affect precipitation variability by providing a significant source of cloud condensation nuclei (CCN). Such pollution effects on precipitation potentially have enormous climatic consequences both in terms of feedbacks involving the land surface via rainfall as well as the surface energy budget and changes in latent heat input to the atmosphere. Specifically, this modeling paper will review and examine the physical processes (latent heating release, cool pool dynamic and ice processes) that determine the invigoration of convection and enhancement of surface rainfall due to increase of CCN concentration. In addition, sensitivity tests on the impact of the evaporative cooling on aerosol-precipitation interactions will be presented.