Research On Convection Cells Nowcasting Method Based On Radar Reflectivity Images

Severe convective weather,as a destructive climate,often causes huge losses to country's economy,agriculture and infrastructure.With unique advantages on high resolution and rich products,Doppler weather radar is an efficient tool for severe convective weather monitoring and nowcasting.In order to increase efficiency and reduce the impact of non-convective cells,traditional nowcasting methods are improved.The specific convective cells are analyzed to help meteorological researchers to monitor and warn severe convective weather.Based on the Doppler weather radar data,the presented work proposes a nowcasting method of convection cells by using radar reflectivity images,which is used to identify,track and nowcast convective cells.The major work of this paper is as follows:(1)Recognition of convective cells based on reflectivity images.The echo factor in radar base data is transformed into reflection images,and then antenna elevation angle is selected according to the specific situation.Convective cells are identified with quality control using region-growing algorithm.(2)Tracking convective cells using combinatorial optimization method.Convective cells features are extracted from reflectivity images and then the three-dimensional centroid is calculated based on the combined reflectance images.The obtained features and three-dimensional centroids are formed into a cost function,which is used to conduct cells tracking according to combination optimization method.(3)Prediction of convective cells based on improved optical flow method.A convective cells prediction algorithm is proposed,which is based on the improved optical flow method,and then the results are further corrected by weighted least square method.Convective cells are decomposed into layers,which are separately predicted by local morphological processing.The nowcasting results of each layer are covered to complete echo area nowcasting of convective cells.Finally,the centroid nowcasting and echo area nowcasting are combined to complete general convective cells nowcasting.The experimental results show that the proposed convective cells nowcasting method based on reflectivity images can accurately identify the convective cells echo area and complete tracking of convective cells of previous time and present time.Meanwhile,it can accurately nowcast convective cells of future time.In summary,the presented work effectively complete the identification,tracking and nowcasting of convective cells,and also meet the needs of practical applications.