长江三峡枯水期区域性强降水的一种重要天气形势

An Important Circulation Pattern of the Regional Severe Precipitation in Dry Season in Sanxia on the Changjiang

利用长江三峡地区６个站１９６１—１９９４年１０月—１月的逐日降水量确定该地区发生区域性强降水的雨日，结合同期的历史天气图分析该地区产生区域性强降水的原因，影响系统和环流形势特征，归纳出长江三峡地区产生区域性强降水的两槽一脊型环流型，并进行逐日反查，概括出两槽一脊环流型产生区域性强降水的前期预报指标。并用１９９５年历史天气图和降水资料进行检验，又在１９９６年１０月、１１月进行试预报。

By using the precipitation data in the dry season from 1961 to 1994 and the same time synoptic map,the severe precipitation factors and features of circulation prior to the occurrence of severe precipitation are analysed.The two trough one ridge pattern is classified from numerous facts and the indexes of forcasting severe precipitation are discovered from the daily data. The forecasting indexes of the severe precipitation for the two trough one ridge pattern are given,it is proved to be practical value in the dry season in Sanxia on the Changjiang in recent two years.