Influence of convection and aerosol pollution on ice cloud particle effective radius

Abstract. Satellite observations show that ice cloud effective radius (r_e) increases with ice water content (IWC) but decreases with aerosol optical thickness (AOT). Using least-squares fitting to the observed data, we obtain an analytical formula to describe the variations of r_e with IWC and AOT for several regions with distinct characteristics of r_e-IWC-AOT relationships. As IWC directly relates to convective strength and AOT represents aerosol loading, our empirical formula provides a means to quantify the relative roles of dynamics and aerosols in controlling r_e in different geographical regions, and to establish a framework for parameterization of aerosol effects on r_e in climate models.