2011年秋季影响陕西关中地区强降水的天气系统及水汽收支分析

Analysis on Synoptic System Influencing Heavy Rain Process in Autumn of 2011 in Guanzhong of Shaanxi and Its Vapor Budget

利用降水、NCEP2再分析资料及GFS预报场资料对2011年秋季关中地区强降水期间的水汽来源、输送、收支进行了研究。结果表明:与夏季降水不同的是关中秋季东边界的水汽输入与降水的开始、结束和强度有非常密切的联系,850 h Pa江淮地区较强的偏东风或东风急流可以作为关中秋季强降水的一个预报指标。秋季台风的发生、移动路径和强度对关中降水有重要影响,台风路径偏东偏北、台风强度偏弱、关中降水量偏少,而副热带高压偏西偏强时,在其南侧的偏东风引导下,台风路径偏西数量明显偏多、强度偏强,关中地区降水量偏多,暴雨频发。

Based on the hourly precipitation data,CMOPPH rainfall data,typhoon track data,NCEP2 reanalysis data and 3-hourly GFS data,the vapor source,vapor transportation and budget during a heavy rain period in autumn of 2011 in Guanzhong were ana-lyzed. The results showed that the vapor transportation from east boundary was closely related with the start and end time of rainfall and its strength in autumn of 2011 in Guanzhong basin,which was different from summer. The strong easterly wind or easterly jet on 850 hPa over Yangtze-Huai area was regarded as an index of strong rainfall prediction in autumn in Guanzhong. The generation,moving path and intensity of Typhoon in the northwestern Pacific had greatly influence on precipitation in autumn in Guanzhong. When the path of typhoon moved eastward and northward and its intensity was weaker,the rainfall was less than normal in Guanzhong. On the contra-ry,when the intensity of western Pacific subtropical high was strong and its location moved westward,the typhoon was more,strong and moved westward,which caused to more and frequent rainfall.