2011年7月陕西一次区域性暴雨过程分析

为了探索陕西区域性暴雨发生发展的机制,提高暴雨预报准确率,利用实况高空观测、自动站观测资料和NCEP1°×1°格点资料,采用天气学诊断方法,对2011年7月28日陕西区域性暴雨过程进行分析。结果表明:500hPa西风槽、西太平洋副热带高压、700hPa及其以下的切变是这次暴雨的主要影响系统,低层大风速带和南海台风的远距离作用是暴雨增幅的重要因子;暴雨区具有强的能量锋和对流不稳定,降水产生在850hPa温湿能等值线密集区偏高值一侧;水汽主要来源于孟加拉湾和南海台风外围;辐合、辐散中心下移是强降水即将发生的一个信号,850hPa以下出现比湿猛增现象对位于秦岭以北的渭河流域暴雨预报有一定指导意义。

Analysis on a Regional Rainstorm in Shaanxi Province in 2011

In order to find out the development mechanism of Shaanxi regional heavy rainstorm and improve the accu- racy of forecasting, with NCEP 1°× 1° re-analysis data, FY-2E-by-hour TBB data and conventional meteorological observation data, the regional heavy rainfall in Shaanxi province on 28th July 2011 are analyzed by synoptic and dy- namical methods. Results show that the main influences to system are 500hPa westerly trough, west pacific subtropi- cal high, 700hPa and 850hPa shear. Low level large wind speed and far distant typhoon influence maybe strengthen the rainstorm magnitude. Storm area has strong energy front and convective instability, precipitation occurs on the greater value side of 850hPa temperature-moisture energy. Water vapor mainly comes from the bay of Bengal and Ty- phoon external. Convergence center and divergence center downwards are the signal of strong precipitation to hap- Den. Soecific humidity below 850hPa increasing rapidly has guidance on forecast of Weihe river vallev rainfall.