地基GPS反演大气水汽总量的初步试验

THE PRELIMINARY EXPERIMENT ON DERIVING INTEGRATED ATMOSPHERIC WATER VAPOR FROM GROUND-BASED GPS

1998年 5～ 6月的“海峡两岸及邻近地区暴雨试验”(HUAMEX)期间 ,同时进行了小规模的地基GPS长时间连续估测大气水汽总量的外场试验。试验中应用探空和地面降水资料与GPS反演结果进行了比较分析。地基GPS反演的大气水汽总量与探空得到的大气水汽总量 ,两者随时间演变的趋势一致 ,两者估算的水汽总量平均偏低 6 .5mm ,两者偏差的均方差为 4.3mm。GPS反演的大气水汽总量随时间明显的呈周期性变化 ,平均周期为 7.2天。从GPS反演的大气水汽总量随时间演变图上可以清楚地看出水汽的积累与释放过程 ,并与地面降水存在一定的对应关系 ,地面降水大多发生在GPS反演的水汽总量处于相对高值且变化率较大的时候。

The field experiment named 'HUAMEX' was conducted in China from May to June 1998. In this experiment, a regional GPS network that included three ground based GPS receiving stations (Shantou, Yangjiang and Haikou) was established to estimate integrated atmospheric water vapor (IWV) continuously. The comparison of IWV estimates derived from GPS and radiosonde observations for a 51 day period at Shantou station is given. Both have an average bias of 6.5 mm,and the root mean square difference is 4.3 mm. The IWV derived from GPS varies with time and it has an obvious period of 7.2 days in average. Moreover, the IWV derived from GPS is compared with the observed surface integrated precipitation hour by hour. The comparison of GPS derived IWV and integrated surface precipitation indicates that there is a good coincidence between them. The variation period of GPS IWV is similar to that of surface precipitation. From the time series of IWV estimated from GPS, the accumulating and releasing processes of water vapor are obvious.