Identifying Particle Growth Processes in Marine Low Clouds Using Spatial Variances of Imager-Derived Cloud Parameters

Abstract

This study proposes a new approach that probes particle growth processes of liquid clouds with satellite observables from passive imagers. Based on the notion that the condensation growth and the coalescence process are characterized by constant cloud droplet number concentration (CDNC) and liquid water path (LWP), respectively, the method adopted used spatial variances of imager-derived cloud properties to estimate relative contributions from these processes embedded in the cloud system. The relative standard deviations (RSDs) of CDNC and LWP associated with their horizontal variances were compared in the form of their ratio. This approach was applied to the GCOM-C/SGLI cloud product, and spatial variability in this RSD ratio was consistent with cloud horizontal morphology such as open- and closed-cell structures. The results suggest that spatial variances of imager-derived cloud properties depict signatures of cloud microphysical processes in the way mappable on the horizontal extent of the cloud system.