An automatic identifying method of the squall line based on Hough transform

Abstract

The squall line is a linear mesoscale convective system often seen in summer, which could bring severe disasters, such as thunderstorms, hails and tornadoes. So, the identification and forecast of squall lines are the important and difficult problems in operational weather nowcasting. In this paper, based on weather radar data an automatic identifying method of the squall line is presented. After image de-noising, extraction of the central axis of strong echo areas, and the Hough Transform, the spatial form and intensity variation characteristics of the reflectivity factors in the radar image are analyzed. On this basis, the automatic identification of squall line could be achieved. This method can overcome the adverse effects of the discontinuity of strong echo areas on the automatic identification of squall lines. The verification of squall line cases shows that the successful identification rate of squall lines is over 95%. Especially, when the boundary of the strong echo area is clear and is in a straight line or minor arc, the identification rate is higher. Overall, this new method has realized the automatic identification of squall lines on radar images, which could greatly improve the accuracy and time-effectiveness of squall line identification, and could provide a solid basis for the automatic forecast of squall lines in operational weather nowcasting.