Competition Between Radiative and Seeding Effects of Overlying Clouds on Underlying Marine Stratocumulus

Abstract

AbstractOverlying cloud can affect the radiative and precipitation features of underlying cloud via its radiative and seeding effects. Using 4 years of CALIPSO and CloudSat observations, this study demonstrates that overlying clouds usually suppress the vertical development of underlying stratocumulus (Sc) by their radiative effect, thus reducing the precipitation, cloud liquid water path and thickness of Sc on a global scale. The radiative effect intensity increases with increasing optical depth (COD) of overlying cloud and decreasing cloud distance between cloud layers. By dividing the overlying clouds into seeder and non‐seeder groups, we find that seeding by overlying clouds can partly or even totally offset the precipitation suppression caused by their radiative effect. The net effect on precipitation of Sc switches from suppression to enhancement when COD of overlying cloud exceeds 0.16. This finding indicates that the competition between radiative and seeding effects of overlying cloud should be considered in cloud‐precipitation interaction.