CWT方法在中国夏季降水水汽来源识别中的应用

Application of CWT Method in Identifying Water Vapor Sources of Summer Precipitation in China

利用Traj Stat软件中的后向轨迹计算模块与浓度权重轨迹（CWT）方法,对中国西部（新疆乌鲁木齐、青海祁连和玛多）和东部（湖南长沙和广东广州）事件尺度的夏季降水水汽来源进行分析,并结合水汽通量进行补充分析。结果发现：（1）乌鲁木齐、祁连、玛多夏季降水受西风水汽影响显著,而长沙夏季降水受西太平洋水汽影响显著,广州夏季降水受印度洋水汽影响显著。（2）5个站点夏季降水均有局地再循环水汽参与。在西部,影响夏季降水的循环水汽主要分布在相对湿度较大的山区、盆地以及蒸发量较大的地区。而在东部,影响夏季降水的循环水汽主要分布在一些地表水体集中的地方。（3）在西部,由于水汽在运移过程中,下垫面起伏大,空气团水汽d值变化除受地表蒸发水汽影响外,还受下垫面地势起伏的影响。在东部,由于水汽在运移过程中,下垫面起伏小,空气团水汽d值变化一般只受地表蒸发水汽影响。

The water vapor sources of summer precipitation over west China（ Urumqi,Qilian and Madoi） and east China（ Changsha and Guangzhou） were analyzed by the backward trajectory calculation module and concentration weighted trajectory（ CWT） of Traj Stat software and combined with water vapor flux. The results showed that：（1） Summer precipitation in Urumqi,Qilian and Madoi was significantly affected by the westerly water vapor,that in Changsha by the Western Pacific water vapor,and that in Guangzhou by the Indian Ocean water vapor;（2） Locally recycled water vapor participated in summer precipitation over 5 sampling sites. The recycled water vapor affecting summer precipitation in west China was mainly distributed in the mountainous areas and basins where the relative humidity was high and the areas where the evaporation capacity was high. In east China,however,the recycled water vapor affecting summer precipitation was mainly distributed in the places where the surface waters are concentrative;（3） Over west China,the change of d value of water vapor in airmass was affected by both evaporation and underlying surface in the process of water vapor movement. Over east China,however,it was generally affected by evaporation only.