摘要:
Based on the GPS data sounded from GPS/MET networks inn Chenzhou area(Yongxing,Yizhang,Guiyang,Rucheng and Guidong) from January to December 2017,the hourly precipitable water vapor (PWV) has been retrieved by using Saas-tamoinen hydrostatic delay model and Bevis empirical formula,combining the surface atmospheric pressure and temperature. The accuracy of PWV retrieved from GPS data,the temporal-spatial variation of PWV and the relationship between PWV with other atmospheric elements as well have been discussed. The results indicate that the reliability of PWV retrieved from GPS data is verified compare with the PWV based on the radiosonde observation sub-second data in Chenzhou area,and the mean bias is 1.717 7 mm,the root mean square error is 3.258 0 mm. The monthly mean PWV presented single peak distribution, which reached the global maximum value in summer(June to August) and dropped down to the global minimum value in winter(November to January). Due to surface evaporation and local circulation,the daily variation of PWV presented two peaks distribution that the relative maximum values assumed at about 16:00 and 00:00,and the variation characteristics of PWV could be used as instruction on the precipitation forecast somewhat because the PWV usually increases before heavy rainfall.%利用2017年1月1日-12月31日湖南省郴州地区(永兴、宜章、桂阳、汝城和桂东)地基GPS/MET站网探测数据,基于Saastamoinen静力延迟模型和Bevis经验公式,结合地面气压和温度反演大气可降水量,并与根据高空气象探测秒数据计算所得探空可降水量对比,讨论GPS可降水量的探测精度.在此基础上进一步讨论郴州地区GPS可降水量的时空变化特征及其与其他气象要素的关系.结果表明,郴州地区GPS反演PWV具有较高精度,较探空实测PWV平均偏低1.717 7 mm,二者均方根误差为3.258 0 mm,能够反映郴州地区大气水汽的变化;郴州地区PWV 表现为夏季(6月、7月和8月)最高、冬季(12月、1月和2月)最低、春季(3月、4月和5月)和秋季(9月、10月和11月)分别逐步增加和减少的单峰型分布;受地表蒸发和局地环流的影响,郴州地区主汛期(6月)逐时平均PWV 表现为双峰型分布,分别于午后16:00和零点左右达到极大值,且在较强降水发生前,PWV 会出现较明显增加,其变化特征对于降水的预报有一定指示作用.