Finestructure of Precipitation and Temperature in a Stratocumulus Cloud

Abstract

A stratocumulus cloud located above a cold front in a midlatitude depression has been observed simultaneously by a K-band radar, instrumented aircraft and radiosondes. The radar recording suggests that convective generating cells near the cloud top present a quasi-periodic organization. This is confirmed by a spectral analysis of reflectivity fluctuations within the generating layer. Aircraft data collected in the precipitation streamers under this layer exhibit systematic fluctuations both in temperature and hydrometeor number density fields. A positive correlation is shown to exist between these fluctuations. A simple numerical model is used to estimate the temperature increase resulting from the release of latent heat by deposition of water vapor on the precipitating crystals. Satisfactory agreement is obtained with the observed temperature and radar reflectivity data.