2009年秋季河南一次连阴雨天气成因分析

采用合成分析和动力诊断分析及统计方法,利用NCEP资料和常规气象观测资料对造成2009年9月6-20日河南省北中部地区15 d连阴雨天气成因进行分析.结果表明:200 hPa高空急流的出现并且维持,南亚高压的偏东偏北,副热带高压的偏西略偏北,以及边界层的东北风(或偏东风),是造成此次长连阴雨天气的主要影响因素;200 ...

Study on forming reasons of a continuous autumn rain event in 2009 in He'nan province

Based on NCEP data and the conventional observation data, forming reasons of a continuous autumn rain event on September 6 to 20 in 2009 were analyzed in the mid-north region of He’nan province. The results indicate that the main reasons causing this process are the occurrence and maintenance of upper level jet in 200 hPa, the leaning eastern and northern South Asia high, the northwestern subtropical high pressure and the northeastern wind in boundary layer (or the easterly wind). The positive anomaly in East Asia westerly jet of 200 hPa and warm anomaly in the middle and upper layers of troposphere (300 hPa) match each other on dynamic relation. The shallow wet layer, insufficient water vapor conditions and the lower level influenced by cold air could make the accumulative total precipitation of the continuous autumn rain lower. Temperature anomaly increases with height and makes high cloud cover increasing, which is the possible reason for few sunshine and lower air temperature.