A Technique for Estimating Low-Level Wind Velocity from Satellite Photographs of Cellular Convection

Abstract

A technique for estimating the low-level wind field from satellite photographs of cumuliform cellular cloud patterns is presented. This technique applies to areas of such patterns, which are frequently photographed behind major oceanic cyclones. The wind speed estimates are obtained by correlating the different cumuliform cellular patterns with three wind speed categories, 0?7, 8?22, and 23?37 knots. This categorization was suggested by results of laboratory experiments, performed by Chandra, in which convection occurred in a layer of air containing vertical shear. The wind direction can be estimated with at worst a ±180° ambiguity; larger scale synoptic considerations can frequently be used to eliminate this ambiguity. Illustrative examples comparing TIROS photographs of cumuliform cellular patterns and surface wind reports are presented.