安徽省夏季暴雨时空分布特征的成因分析

The analysis on possible causes of spatio-temporal characteristics of Torrential Rain in Anhui Province

利用安徽省16台站1960—2012年逐日降水资料,建立暴雨指数,分析了安徽省夏季暴雨雨量、日数及强度的时空分布特征,并讨论了暴雨不同空间型的大气环流和海温特征。结果表明:安徽省夏季暴雨雨量、日数及强度均呈北少南多分布。暴雨区从6月至8月由南向北推进,有明显的月变化和地区性差异。暴雨指数空间型主要分为三类:一致型、南北型和中间型,其中一致型占41.5%,南北型占22.6%,中间型占15.1%。一致型与同期东亚—太平洋遥相关(EAP)关系密切,其负相位对应暴雨指数偏强年,反之亦然。同时其与前期冬季亲潮海区温度异常有正相关,相关性最强在同年1月;南北型与中高纬冷空气南进程度及垂直运动有关。

The spatio-temporal characteristics of precipitation amount, days and intensity of torrential rain are discussed by analyzing daily precipitation data of 16 stations in Anhui Province from 1960 to 2012. Meanwhile, by taking advantage of torrential rain index, the atmo-spheric circulation and sea surface temperature are analyzed under different spatial modes. The results showed that the rainfall amount, days and intensity are all greater in the south than in the north of Anhui province. From June to August, torrential rain area moves from south to north progressively. There are significant monthly variations and regional differences. The spatial modes of torrential rain index is divided into three categories:the first mode called consistent type indicates that the rainfall is consistent in all areas, the second mode called north-south type indicates that the rainfall is opposite in north and south, and the third mode called intermediate type indicates that the central part is dif-ferent from that in south and north. These three spatial modes shown above accounts for 41.5%, 22.6%, and 15.1%, respectively. East Asia-Pacific teleconnection (EAP) is related to theconsistent mode, and its negative phase corresponds to strong torrential rain index years, and vice versa. Meanwhile, the mode has a positive correlation with SSTA in key area of Oyashio current of previous winter, and the correlation maxi-mum appears in January. The north-south mode is related to the extent of cold air toward south and vertical movement.