GPS可降水量在湖北暴雨预报中的指示性

Indication of GPS Precipitable Water Vapor for Rainstorm Forecast in Hubei

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10mm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6h和12h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40mm和大于等于55mm,在湖北中东部分别为大于等于52mm和大于等于60mm;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45mm;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1h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1h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。

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 6hours 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 1hour 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 1hour before.