宁夏冰雹的分布特征

应用1961～2004年宁夏各气象站地面观测资料，统计分析了宁夏冰雹的时空分布特征，探讨了宁夏冰雹产生的主要源地和移动路径。分析表明：20世纪80年代为宁夏冰雹频发期，90年代有减少的趋势；近10年来冰雹大为减少，年际变化比较大，有一定的周期性。冰雹多发生于春末至盛夏，6月为频发期；87％出现在中午至傍晚前后；71．84％的降雹持续时间在1～10min之间。初雹最早发生在3月中旬，终雹最晚结束在10E下旬。有2个频发中心，即宁夏南部的六盘山区和北部的贺兰山区，有“山地多、平川少、南北多、中部少”的地域分布特征。降雹线大部分呈NW—SE走向，移动路径多从西北向东南方向移动；主要发源于六盘山系和贺兰山沿山。

Characteristics of Hail Distribution in Ningxia

Using the hail data in Ningxia of 1961-2004,statistical analysis on spatial-temporal characteristics of hail distribution,main source areas and moving routes in Ningxia are made.The results show that the 1980s of the 20th century witnessed frequent hail in Ningxia,while the hail occurrence declined in the 1990s.The hail times decreased dramatically in recent 10 years.The annual variation is relatively great and has certain periodicity.Most of the hail occurred in late spring or beginning of summer,most in June.87% of the hail occurred from afternoon to the evening.71.84% of the hail lasted for 1-10 minute(s). The first hail occurred in mid March,the last was in the late October.The Mt.Liupan and Helan are the 2 centers of hail events in south and north.The landform distribution in this region is more mountains than plains and more mountains in the south and north than that in the central part.The routes of most of the hail are NW-SE and the main source areas of hail are Mt.Liupan and Helan.