GPS可降水量在湖北暴雨预报中的指示性

通过对2012年5—9月湖北省59个GPS/MET站可降水量资料、全省自动站雨量资料以及实况高空资料的分析发现：①同址观测的GPS PWV与探空-PWV相关性高，误差小，有降水时相关性下降。②有降水时山地比平原地区的GPS PWV普遍偏低10 mm左右。③69%暴雨出现前GPS PWV会上升，不上升的则已达到较高值。GPS PWV单站6 h和12 h变量为正，对暴雨开始的指示性较好。④不同类型暴雨的GPS PWV特征不同：西风系统型和副热带高压影响型局地暴雨中心均对应GPS PWV高值区，其GPS PWV阈值在湖北西部分别为大于等于40 mm和大于等于55 mm，在湖北中东部分别为大于等于52 mm和大于等于60 mm；台风影响型局地暴雨大多位于GPS PWV高值区附近的密集带，GPS PWV阈值为大于等于45 mm；区域性暴雨需在有利降水的天气形势下考虑PWV，暴雨中心对应GPS PWV高值区，且GPS PWV高值中心较暴雨中心提前1 h出现。⑤暴雨中心位于GPS PWV水平分布密集带的情况有3种：个别影响系统移动较快的暴雨、台风影响型局地暴雨、个别山区暴雨。⑥利用GPS PWV高值区叠加地面辐合区判断未来1 h暴雨区，对湖北中东部暴雨的指示性较好，但对湖北西部山区暴雨的指示性较弱。

Indication of GPS Precipitable Water Vapor for Rainstorm Forecast in Hubei

The PWV data of GPS/MET from May to September 2012, the automatic rain gauge data and the radiosonde data are analyzed. The results are as follows: (1) There existed high correlation and small errors between GPS PWV and radiosonde PWV measurements observed at the same station, but less obvious correlation when there was rainfall. (2) GPS PWV values were about 10 mm lower on plains than in hilly areas when rainfall. (3) 69% of GPS PWV values rose before a storm appearing, and in the cases of not rising, the GPS PWV reached a higher value. When the GPS PWV values of 6 hours and 12 hours were positive, it is indicated that rainstorm will start. (4) GPS PWV characteristics were different under different types of rainstorms: the storm centers of local rainstorms caused by the westerly system and subtropical high in Hubei Province correspond with GPS PWV high values, with the GPS PWV threshold values being less than 40 mm and 55 mm, respectively, in west of Hubei Province and the GPS PWV threshold values being less than 52 mm and 60 mm, respectively, in mid east of Hubei Province. The local rainstorms affected by Typhoon usually lie around the dense zones of GPS PWV nearby the high values area, with the threshold values less than 45 mm. During heavy rain processes, GPS PWV high value centers appear 1 hour earlier comparing with the heavy rainfall centers under favorable weather conditions. (5) There were three kinds of situations in which storm centers locate in GPS PWV dense zones: rainstorms caused by a fast moving storm systems, local rainstorms affected by a Typhoon, rainstorms in mountains areas. (6) It can be indicative of rainstorms very well in the mid eastern Hubei Province, but poor in the mountainous area of the western Hubei, while comprehensively considering GPS PWV high values and ground convergence zone 1 hour before.