关键词: 天气关键区, 动态相似, 延伸期天气过程, 西江流域

Abstract: In order to forecast heavy precipitation processes in the Xijiang River Basin, the synoptic key regions were determined firstly on the basis of 500 hPa atmospheric circulation synthetic analysis in more heavy rainfall years by using daily rainfall data from 135 meteorological stations in the Xijiang River Basin and NCAR/NCEP daily reanalysis data of 500 hPa geopotential height in the northern hemisphere from 1960 to 2017. Furthermore, the dynamic similarity ensemble-mean method in synoptic key regions was adopted to perform extended-range forecast tests of heavy rainfall processes. Specifically, the empirical orthogonal functions (EOF) method was used to extract and reconstruct principle spatial patterns of 500 hPa geopotential height in past few months, and the years with most similarities were chosen by comparing the constructed circulation patterns at the same period in each year via an analogous precursor method. Finally, the periods of heavy precipitation processes in the Xijiang River Basin in June of 2008 were forecasted by using the above method, and the prediction effects of heavy precipitation processes in recent five years were tested. The results indicate that heavy precipitation processes over the Xijiang River Basins could be forecasted well based on the synoptic key region analogous method, which could be used in actual extended range weather forecast service.

Key words: synoptic key areas, dynamic similarity, extended-range weather processes, the Xijiang River Basin