GPS遥感大气可降水量在暴雨天气过程分析中的应用

Applications of Precipitable Water Vapor Monitored by Ground-Based GPS to Analyzing Heavy Rain Event

利用北京市气象局地基GPS监测试验网遥感大气可降水量（PWV）数据，分析2004年汛期暴雨天气过程PWV的变化特征及其与降雨量、降雨强度的关系；通过分析地面、高空的位势高度场、风场，以及比湿外水汽通量Q及水汽通量散度AQ等物理量诊断场分布，研究天气系统与大尺度水汽输送、辐合的关系，大尺度水汽输送、辐合与PWV变化的关系；探讨GPS遥感大气水汽资料在预报强降雨天气过程中的应用。得出：PWV的增长方式受当地天气系统的支配和制约，对于明显降雨过程，当地面、高空天气系统有利于暖湿空气的输送时，在北京附近形成等湿度线密集区，PWV逐渐增长（降雨开始前的13-24h）的趋势；当地面、高空有辐合系统东移或生成，或有中小尺度天气系统影响时，PWV显著增长（降雨开始前的3～4h）；当PWV大于某阈值后出现较强降雨，PWV值及增量的大小与降雨量的大小没有明显的关系。

Based on the Monitored data of the GPS network in Beijing, the relationship between the variation characteristics of preeipitable water vapor （PWV）in the rainstorm event during 2004 flood season and its rainfall and intensity was analyzed. The results show that the increase of PWV was often restricted by the local weather system, when weather system in ground and upper air picture make for the transportation of warm and moisture air, isohume denseness section was formed nearby Beijing, the PWV was increasing during 13-14 hours before rainstorm appearance; when there was convergence system moving eastward or mesoscale weather system forming, PWV increased significantly during 3-4 hours before rainstorm, heavy rain appeared after value of PWV above threshold, but the value of PWV and increment did not correspond to the rainfall.