Evaluating Reanalysis of Vertical Cloud Structure Across a Stratocumulus to Shallow Cumulus Transition using CloudSat-CALIPSO Observations

Abstract

Stratocumulus clouds play an important role in the global energy balance. Thick layers of stratocumulus clouds over the subtropical oceans gradually thin and transition into shallow cumulus clouds as they traverse from higher latitudes towards the equator. Since these clouds are so widespread, they have a significant radiative effect by reflecting solar radiation, which helps control the cooling of the climate system. Atmospheric reanalyses are uniformly gridded global datasets of atmospheric parameters sourced from historical, current, and model-assimilated observations of the atmosphere. This investigation quantifies the degree to which reanalysis products accurately simulate this cloud regime transition by comparing them to observational satellite data. The physical atmospheric state parameters responsible for reanalysis-observation differences are also identified. Analysis reveals that all reanalysis products exhibit shortcomings in accurately simulating the stratocumulus to cumulus transition, and differences in dynamical and thermodynamical background conditions within each reanalysis environment affect the degree to which each reanalysis depicts cloud coverage and regime type. Understanding errors in model and reanalysis representations of this physical cloud regime transition process will allow researchers to utilize these products with greater awareness of their limitations.