2002年台风Ramasun影响华东沿海期间可降水量的GPS观测和分析

GPS Observation and Analysis of Precipitable Water Vapor during Typhoon Ramasun in 2002 Influencing East China Coast

介绍了 2 0 0 2年建成的长江三角洲地区GPS (全球定位系统 )网对台风Ramasun影响华东沿海地区时可降水量的探测 ,指出GPS探测的可降水量 (PWV)与加密探空资料所计算的可降水量具有高度的一致性。通过对多站GPS资料时间序列的分析 ,揭示了在台风影响过程中PWV的三个阶段的变化特征 :在台风降水产生前PWV都有一个急升的过程 ,PWV的急升时间长短、升幅、量值大小反映了水汽累积情况 ,它与台风过程降水总量、每小时降水量大小有较好的对应关系 ;PWV急升达到峰值后进入高值波动阶段 ,一般在达到峰值后 7～ 1 0小时开始出现明显的降水 ,在这一阶段中PWV时间序列的波动和空间分布特征与台风降水的短时变化和螺旋雨带演变有较好的对应关系 ;PWV的急降则反映台风降水即将结束。

The P WV data from the Global Positioning System(GPS) network in the Yangtze River Delta during typhoon Ramasun influencing East China Coast is analyzed The coincidence between the P WV from GPS and the P WV from radiosondings shows good quality of P WV data from GPS Through the analysis of the time series of P WV data from GPS of 14 GPS stations, it is revealed the features of three stages during the typhoon's influencing East China Coast. When the typhoon approached the Yangtze River Delta, the P WV in the area of 850～900 km ahead from the typhoon center begins to increase rapidly, the keeping up time, the range and the maximum of the P WV increasing reflect the intensity and the accumulation of the water vapor They relate well with the total rainfall and the maximum of the hourly rainfalls during the typhoon influence After P WV reaching the peak, the P WV enters a fluctuation period with high P WV magnitudes, the precipitation occurs generally 7～10 hours later. In this period, the temporal fluctuation and the spatial distribution correspond well to the variation of the typhoon precipitation in short time and the evolution of typhoon's spiral rainfall bands. Finally, the P WV decreasing rapidly suggests the end of precipitation