Satellite-Based Estimation of Cloud Top Radiative Cooling Rate for Marine Stratocumulus

Abstract

Cloud top radiative cooling rate (CTRC) is the leading term in the energy budget of a marine boundary layer capped by stratocumulus. It plays a significant role in the formation, evolution, and maintenance of the stratocumulus cloud system. This study demonstrates the feasibility of estimating the CTRC, with high accuracy, from passive satellite data only. The estimation relies on a radiative transfer model with inputs from satellite-retrieved cloud parameters in combination with reanalysis sounding that is revised, in a physically coherent way, by satellite data. The satellite-based estimates CTRC agree with ground-based ones to within ~10%. The high accuracy largely benefits from the good capability of satellite data in constraining parameters of most influence to the CTRC such as free-tropospheric sounding, cloud top temperature, and cloud optical depth. Applying this technique, we generate a climatology of CTRC during summer over the Southern Hemisphere tropical and subtropical oceans.