Convective Weather Forecast Based On Boundary Layer Convergence Lines

Convective weather had brought about great impact on our lives. At present, the prediction of the emerging convective storm is mainly composed by the forecasters who analyze the radar image with the help of professional knowledge. In the early stage of formation of convective weather, the weather system will exist some characteristics of disasters, which were called PBL convergent lines. With the development of computer science, based on the structural characteristics of Convective weather systems, and to make Strong storms forecast achieve computer automation, the process can be simulated by computer through image processing technology and the basic methods of pattern recognition. This will reduce forecasters'subjectivity and provide forecast theoretical basis for the forecaster, at the same time, improve forecast accuracy.The automatic identification and extraction method of PBL convergent lines is given in this paper. With good robustness and universality, this method could obtain satisfactory results. Meanwhile, extract some meteorological characteristics near the convergence line region, and make a brief for strong convective weather with PBL convergent lines. This paper has completed the following two parts:1. The automatic extraction of PBL convergent lines. Convergence lines reflect very complex in the reflectivity picture, which are belt-shaped regions with winding, possibly branching, uncertain width and changing value in the Doppler radar images and makes it impossible to use the conventional shape recognition method directly. In the paper, an algorithm called "detection window" was proposed for extracting the irregular belt-shaped region from complex background. Increase the scale of the detection window, change detection conditions, design exploration path and process the strip zone, the algorithms run faster, improve accuracy and reduce error rate. Then using the ribbon complexity to calculate the band structure; extracted skeleton, cut off the spur. Get the basic PBL convergent lines.2. Extract the equidistant from both sides of the convergence line velocity information, according to the convergence line fitting a straight line, infer the direction of the convergence line and the development of sports storm by the speed of information movement, and can identify the convergence of the lines once again. In the short-term forecasting system, there is time requirement for the strong convective weather forecast, under this amount of time, the convergence line need be automatically recognized in a certain time interval. Thus the boundary layer convergence lines will greatly improve the recognition rate, relying on such meteorological features, and improve reliability for severe weather forecasting in the future development.In summary, this paper does the initial research by the using of boundary layer convergence lines to forecast the development of severe convective. And the algorithms involved have been realized by program which presents strong stability and satisfactory results in the process of sample test.