怀化地区强降水过程中的GPS可降水量特征分析

利用改进的天顶静力延迟（ZHD）模型和本地化水汽权重平均温度（Ts）模型反演怀化地区GPS可降水量（GPS-PWV），并结合自动气象站逐小时资料分析了2017年怀化地区大气水汽变化及汛期14次暴雨以上降水过程的GPS-PWV演变特征。结果表明：GPS-PWV可较好反映怀化地区大气水汽的变化特征。怀化地区可降水量-气压（PWV-P）分布月变化特征明显，冬季PWV较低且变化范围较小，降水发生时气压较夏季平均高14.75 hPa；春季PWV逐步增大，降水发生时气压较冬季有所降低；夏季PWV为全年最高，降水发生时气压则降至全年最低值；秋季PWV-P数据逐渐分散并向可降水量低值区移动，分布情况逐步趋近冬季。2017年汛期怀化地区14次强降水过程中PWV均高于各月均值，最大小时降水量与最大PWV存在较好对应关系；降水开始前，PWV出现较明显上升，且多伴随气压较明显下降，可为局地强降水短临预警提供较好参考。

Characteristics of GPS Precipitable Water Vapor During Heavy Rainfall in Huaihua District

Using the precipitable water vapor (GPS-PWV) inversed from ground-based GPS that based on the advanced ZHD model and localized Ts model, as well as integration hourly meteorological data from automatic weather station, the atmospheric water vapor variation characteristics and evolution features of GPS-PWV during 14 heavy rainfall events are analyzed at Huaihua in 2017. As the results shown, GPS-PWV could reveal the atmospheric water vapor variation characteristics of Huaihua region. The monthly change of PWV-P data pair is evident. The PWV appears a lower value with a smaller range accompanied by a 14.75hPa higher surface air pressure than that in summer when precipitation occurs during winter, which gradually increases with a lower surface air pressure while precipitation during spring. In summer, the PWV rises to the annual peak value with the lowest surface air pressure under rainfall, and it scatters to low value area in autumn. In 14 heavy rainfall events at Huaihua during flood season of 2017, all of the PWV values exceed corresponding monthly mean, besides there is a well corresponded relationship between the maximum rainfall and maximum PWV in hourly scale. Before the heavy rainfall occurred, the PWV increases comparatively distinctly with a clear decrease of the surface air pressure, and that could be a preferably reference point in the local strong precipitation nowcasting.