2007年淮河流域暴雨期间大气环流特征分析

利用NCAR/NCEP再分析资料及国家气象信息中心30年气候平均降水资料,通过动力诊断与分析手段研究了2007年6—7月发生在我国淮河流域的暴雨。结果表明,淮河流域的环流垂直结构和降水有着非常好的对应关系。暴雨期间,鄂霍茨克海阻高与乌拉尔山阻高这种双阻高形势对于淮河流域的持续降水提供了很好的条件;南亚高压高层(200 hPa)基本为正散度区,低层(850 hPa)为负散度区,上下层强烈的抽吸结构对暴雨的发生也是非常有利的条件,同时,在淮河暴雨期问,南亚高压(200 hPa)与500 hPa西太平洋副热带高压有着相向而行的移动路径;位涡对于分析冷空气的活动,有着比较清晰的意义,暴雨发生前,有明显的正位涡异常从高纬度向低纬度伸展。大气非绝热加热分析结果显示,视热源和视水汽汇两者的高值中心与相应时段暴雨中心位置一致。

Analysis on General Circulation Characteristics of the Heavy Rainfall During June-July 2007 in Huaihe Valley

Based on the NCEP/NCAR reanalysis data and the 30 year average precipitation data from National Meteorological Information Center, in terms of the dynamic diagnosis and analysis, the heavy rainfall during June-July 2007 in the Huaihe Valley has been analyzed. The results are as follows: the vertical structure of the circulation pattern corresponded well with the precipitation in the Huaihe Valley. During the heavy rainfall, the double blocking highs, which were located in the Okhotsk Sea and Ural Mountain respectively, provided the favorable condition for the consistent rainfall. The divergence was positive in the upper level (200 hPa) and negative in the lower lever (850 hPa) of the South Asia high. The pumping of the intense field was in favor of the heavy rainfall. The South Asia high and the 500 hPa West Pacific subtropical anticyclone moved toward each other. The potential vorticity (PV) could explain the activity of the cold air clearly. Before the occurrence of the heavy rainfall, there were obvious positive PV anomalies extending from the high latitude to the low latitude. Heating revealed that the large centers of the apparent heat source and moist sink corresponded well with the heavy rainfall center of the same period of the time.