Abstract:Based on the research of a differential filtering method retrieving composite shear from Doppler radar velocity data, considering the problems of this method, such as the number of edge detection points is too small, combined with the least square’s advantage on Linear fitting and radar data’s radial distribution character, this paper presents a method of least squares based on different “fitting window”. These two methods are compared and analyzed by using computing positioning accuracy method and so on. The method of least squares is better than the differential filtering method on positioning accuracy, identification ability, edge detection and so on. During the 2008 Beijing Olympic Games, by using the method of least squares, the radial velocity azimuth composite shear weather product provides some important information for the weather modification.