Preliminary comparison of CloudSAT‐derived microphysical quantities with ground‐based measurements for mixed‐phase cloud research in the Arctic

Abstract

The omnipresent existence of thin, mixed‐phase clouds in northern polar latitudes presents special challenges to CloudSAT as it attempts to map radiatively relevant cloudiness around the globe. In this work, retrieved cloud properties of Arctic mixed‐phase clouds observed simultaneously in Eureka, Canada by ground‐based cloud radar and lidar, and by the CloudSAT Cloud‐Profiling Radar (CPR) are compared. Through these comparisons, we evaluate the efficacy of identification of precipitation and assignment of cloud type by the 2B‐CLDCLASS product, as well as the accuracy of microphysical retrievals from the 2B‐CWC‐RO product. These preliminary comparisons result in the following findings with regard to the CloudSAT retrievals: (1) The cloud detection algorithm worked well, detecting all clouds observed from surface based sensors. (2) Precipitation was not well identified, and was often mislabeled as cloud. (3) Both liquid and ice particle number densities retrieved by CloudSAT are found to be 1 to 2 orders of magnitude too high when compared to surface‐based retrievals and previous studies of these cloud types. (4) CloudSAT particle effective sizes are often too large, with the exception of the largest particles, which are misidentified as liquid. (5) Water contents show the best agreement between the two retrieval types, as well as with measured values from outside studies. All comparisons were completed for raw liquid and ice retrievals, as well as for “composite” retrievals that partition liquid and ice contributions to measured reflectivity through a temperature‐dependent algorithm. Differences found for these limited cases imply that careful analysis is required for application of these cloud products to mixed‐phase cloud research. Furthermore, these differences help highlight specific assumptions within the CloudSAT algorithms that are in need of improvement to complete mixed‐phase cloud retrievals.