500 hPa球函数谱异常用于我国东部汛期降水预测的尝试

AN ATTEMPT TO PREDICT EASTERN CHINA SUMMER RAINFALL USING ANOMALOUS 500 hPa SPHERICAL FUNCTIONS

用北、南半球 5 0 0hPa月平均位势高度场球函数系数资料代替格点资料 ,用区域降水指数表示华北、江淮、华南三区汛期 (6～ 8月 )降雨。通过引进复相关系数和构造复相关系数场模 ,分析了半球 5 0 0hPa环流与我国东部汛雨异常的同时和时滞相关联系。在此基础上 ,选取 5月份北半球、1月份南半球球函数系数与东部汛期降水作时滞的奇异值分解。由此得到的预测关系在 1998～ 2 0 0 1年汛期降水预报试验中取得了一定效果 ,从而对 5 0 0hPa环流的球函数系数资料在区域月。

Spherical function coefficients of 500 hPa monthly-mean height field of the Northern and Southern Hemisphere are used here instead of grid data. Sectorized precipitation index is representative of summer rainfall of Huabei, Jianghuai and Huanan areas. Through the introduction of complex correlation coefficients and the definition of the module of complex correlation field, this paper analyses synchronous and time-lagged correlation between 500 hPa Hemisphere circulation and summer rainfall anomaly in Eastern China, based on which singular value decomposition is made to Eastern Chinese summer rainfall and 500 hPa Southern Hemisphere spherical function coefficients of January as well as Northern Hemisphere spherical function coefficients of May. A forecasting relation is constructed from the time coefficients and works well in the 1998 to 2001 summer rainfall prediction test. These provide a good basis for the application of 500 hPa spherical function coefficients in area of short term climate prediction.