PNNL

Abstract

Aerosols have significant and complex impacts on regional climate in East Asia. Cloud-aerosol-precipitation interaction (CAPI) remains most challenging in climate studies. The quantitative understanding of CAPI requires good knowledge of aerosols, ranging from their formation, composition, transport, as well as their radiative, hygroscopic, and microphysical properties. A comprehensive review is presented here centered on the CAPI based chiefly, but not limited to, publication in the special section named as EAST-AIRcpc, concerning (1) observation of aerosol loading and properties; (2) any relationships between aerosols and meteorological variables affecting CAPI; (3) mechanisms behind CAPI; and (4) quantification of CAPI and their impact on climate. Heavy aerosol loading in East Asia has significant radiative effects by reducing surface radiation, increasing air temperature, and lowering the boundary layer height. A key factor is aerosol absorption which is particularly strong in central China. This absorption can have a wide range of impacts such as creating an imbalance of aerosol radiative forcing at the top and bottom of the atmosphere, leading to inconsistent retrievals of cloud variables from space-borne and ground-based instruments. Aerosol radiative forcing can delay or suppress the initiation and development of convective clouds whose microphysics can be further altered by the microphysical effect of aerosols. For the same cloud thickness, the likelihood of precipitation is influenced by aerosol: suppressing light rain and enhancing heavy rain, delaying but intensifying thunderstorms, and reducing the onset of isolated showers in most parts of China. Rainfall has become more inhomogeneous and more extreme in the heavily polluted urban regions.