Convective and Stratiform Components of a Winter Monsoon Cloud Cluster Determined from Geosynchronous Infrared Satellite Data

摘要

A technique originally devised by Adler and Negri (1988) for estimating the convective and stratiform precipitation areas and amounts of mesoscale convective cloud systems from infrared satellite imagery has been applied to a large cloud cluster observed over the South China Sea during the Winter Monsoon Experiment (WMONEX). The technique was modified to obtain agreement with a previous analysis of ground-based radar data obtained in a limited part of the cluster. The modifications included altering the method for identifying convective cells in the satellite data, accounting for the extremely cold cloud tops characteristic of the WMONEX region and modifying the threshold infrared temperature for the boundary of the stratiform rain area.After obtaining agreement with the radar analysis over a limited portion of the cluster's area and lifetime, the satellite technique was applied to the entire cluster over its full lifetime. The locations of the convective and stratiform rain areas found in this extended analysis were consistent with WMONEX research ship and aircraft data of the cluster. The evolution of total convective and stratiform precipitation indicated by the satellite analysis over the cluster's lifetime was qualitatively consistent with previous radar analyses of other equatorial cloud clusters, except that this cluster appears to have developed a particularly strong stratiform component during its mature stage.The successful application of the Adler and Negri technique to the WMONEX cloud cluster provides encouragement for the use of this method; to develop satellite-based climatologies of the convective-stratiform internal structure of cloud clusters over large regions of the tropics where radar data are not typically available. It also appears that this technique will be a useful complement to future spaceborne precipitation-measuring radar systems.