利用地基GPS获取实时可降水量

Real-time PWV Obtained by Ground GPS

利用PBO观测网络的17个连续运行参考站GPS观测数据采用双差的方法估算对流层,并对初始精确坐标加以紧约束,对影响测站位移的形变等加以改正,采用组合超快星历,每60s计算一次得到近实时的可降水量。根据与静态计算结果比较显示,两者吻合性高度一致,大部分站点相差不到2mm,其内符合精度可达1mm,延迟少于4min,可以满足实时数值天气预报的要求。根据基线的长度对以上结果分析得到地基GPS反演降水量的可行性区域范围,并探讨了测站间高差大小对获取可降水量精度的影响。

It is important to inverse the high accuracy real-time PWV by ground GPS for the short term prediction of bad weather.Currently the orbit and clock errors of satellites from ultra-rapid ephemeris are the main factors constraining the improvement of PWV＇s precision,the former usually affects the acquiring of PWV by differential GPS.17 GPS CORS sites from PBO network of America are used to test for estimating the ZTD by double differential mode with the tightly constrained initial precise coordinate as well as the correction of site displacements by combined ephemeris,the near real-time PWV was computed every 60 seconds.By comparing the result to the static mode,it shows high coincide between both the modes with most stations have only 2 mm differences or smaller,the inner precision can reach 1mm,the delay is less than 4 minutes and can meet the requirements of the real-time numerical weather prediction.The feasible region of PWV inversed by the ground GPS is acquired after analyzing the affection of baselines length on the above results,and also the affection of the heights difference on the PWV＇s accuracy the is discussed.