香港地区2013—2016年地基GPS大气可降水量与实际降雨量的比较

本文在利用ECMWF的数据对由GPS观测资料计算的大气可降水量（Precipitable Water Vapor, PWV）进行精度评定的基础上，基于谐波分析的方法对香港地区不同方位5个测站2013~2016年连续4年的PWV(GPS)和实际降雨量进行比较。结果表明：地基PWV(GPS)相对于PWV(ECMWF)月均值的均方根在1.02 mm-3.07 mm之间，偏差在-2.14 mm-2.52 mm之间。地基PWV(GPS)和实际降雨量都呈现明显的周期性，两者每年峰值出现的时间有非常一致的对应关系。PWV的峰值出现在7月，振幅在14.65 mm与16.79 mm之间；实际降雨量峰值同样出现在7月，振幅在147.64 mm与211.01 mm之间。5个测站PWV年增长率为正，表明近4年香港地区PWV呈现出增长的趋势；而实际降雨量年增长率除HKOH测站为正外，其余站点均为负，总体呈现出逐年减少的趋势。

Comparison between GPS-derived PWV and Rainfall During 2013 to 2016 over Hong Kong

The atmospheric precipitable water vapor (PWV) is derived from GPS observations of 5 stations over Hong Kong during four years from 2013 to 2016 and the accuracy of PWV(GPS) is assessed with PWV(ECMWF). The PWV(GPS) is then compared with rainfall based on harmonic analysis. The results show that taking PWV(ECMWF) monthly means as references, the RMS of PWV(GPS) monthly means is between 1.02 mm and 3.07 mm and the bias is between -2.14mm and 2.52mm. Both PWV and rainfall have similar periodic characteristics. The peaks of PWV occur in July with amplitudes varying between 14.65 mm and 16.79 mm. The peaks of rainfall also occur in July and the amplitudes are between 147.64 mm and 211.01 mm. The annual increase rate of PWV is positive at each GPS station, indicating that PWV over Hong Kong has an increasing trend during the past 4 years.While the annual increase rate of actual rainfall is negative except in HKOH station, which means a decreasing trend during the 4 years.