Cloud Ice Processes Enhance Spatial Scales of Organization in Arctic Stratocumulus

Abstract

AbstractStratocumulus clouds around the globe tend to organize into cellular patterns, a phenomenon that has been primarily studied for the subtropical trade wind region. However, stratocumulus are also prevalent in high latitudes, where they often occur as mixed‐phase clouds. Yet little research has been conducted regarding mechanisms of cloud organization in the mixed‐phase regime. In cloud‐resolving model simulations we investigate the processes driving organization in open‐cell mixed‐phase stratocumuli. Similar to warm‐phase clouds, mixed‐phase clouds develop a subcloud circulation of evaporated/sublimated precipitation, cold pool formation, and consecutive updrafts driving new convective cells. For a larger ice to liquid water ratio, we find locally stronger precipitation and larger cloud cells. Hence, a higher concentration of ice nucleating particles can induce a breakup of the stratocumulus organization, with implications for the radiative balance at the surface. A decrease in cloud condensation nuclei concentration is also found to intensify precipitation and impact cloud organization.