2014年与2017年湖南省7月2次暴雨天气对比分析

摘要

Using conventional observation data,automatic station data and NC reanalysis data,the causes of two rainfall weathers in Hunan Province from July 12 to July 14,2014 and July 8 to July 10,2017 were comparatively analyzed from the aspects of weather conditions,mesoscale systems and physical quantities.The results showed that the mid-high latitude ridges of Eurasia were northeast-southwest,which was favorable for the development of the upper-level trough and conducive to the southward movement of ground-level cold air.The 588 dagpm line of the subtropical high was east northeast-west southwest and the west ridge was 109oE nearby,which was conducive to the cross-hungry of cold and warm air in Hunan Province.During the rainstorm in Hunan area,the low-level southwest jet 8-16 m/s was most conducive to the occurrence of rainstorm;The mesoscale convergence line played a direct trigger role in the process of heavy rainfall.The areas with heavy rainfall were basically located in the vicinity of 850 hPa big wet area (greater than 15 g/kg).The vertical ascending velocity and the distribution of K index,SI index and CAPE also had good consistency with the falling area and intensity of the two precipitation processes.%应用常规观测资料、自动站资料及NC再分析资料,从天气形势、中尺度系统、物理量等方面对2014年7月12-14日和2017年7月8-10日湖南省2次暴雨天气的成因进行对比分析.结果表明,欧亚中高纬槽脊为东北-西南向,该结构有利于高空槽的发展,利于带动地面冷空气的南下,副高588 dagpm线为东东北-西西南向,西脊点在109°E附近,利于冷暖气流在湖南地区的交馁;湖南地区的暴雨过程中低层西南急流8 ～ 16 m/s最有利于暴雨出现;中尺度辐合线在强降水过程中起着直接的触发作用;强降水落区基本上位于850 hPa比湿大值区(15g/kg以上)附近;垂直上升速度以及K指数、SI指数和CAPE值的分布与这2场降水过程的落区及强度也有较好的一致性.