不同类型降雨过程中GPS可降水量的特征分析

Characteristics of GPS-retrieved precipitable water vapor in different precipitation types

利用成都地基GPS观测网2007年8月21日～2008年11月30日观测数据,结合地面自动气象站网资料反演GPS大气可降水量(PWV)。选取夏季暴雨,秋季绵雨和冬季雨雪天气过程分析GPSPWV在不同类型降雨天气过程中的演变特征及日变化规律。结果表明,发生在不同季节的暴雨对应PWV的演变有所不同,盛夏暴雨发生在PWV由峰值向波谷变化过程中,夏末的暴雨则出现在由波谷向波峰转变阶段,降雨前GPSPWV的增减速率可很好地预示其后的暴雨强度。在秋季绵雨中PWV的连续大幅递增或递减可作为降雨开始或结束的预报依据。GPSPWV在降雨天气分析及预报中具有重要的指示意义。

The precipitable water vapor （Pwv） data are retrieved from the ground-based Global Positioning System （GPS） observational network together with the automatic weather stations in Chengdu region during the period of August 21, 2007 to November 30, 2008. The GPS-retrieved Pwv data are analyzed for diurnal cycle characteristics as well as for different precipi- tation types including the summer heavy rainfall, the autumn continuous rain and the winter snow-rainfall. The result shows that storms occurred in different seasons correspond the distinct Pwv. For example, the summer storms are associated with the change of Pwv values from peaks to troughs. The opposite Pwv change characteristic to the summer heavy rainfall is found at the end of summers. The result suggests that the change ratio of Pwv values before a rainfall event may well indicate the inten- sity of subsequent heavy rainfalls. Significant variations in Pwv ratios during the autumn continuous rain can potentially predi- cate the beginning or the ending of a rainfall event. The real-time consecutive GPS-retrieved Pwv data can thus be used in operational precipitation forecasting.