夏季水汽输送特征及其与中国降水异常的关系

利用1958－1999年NCEP／NCAR再分析资料研究了水汽输送特征，表明：全球纬向水汽输送在南北半球中高纬度由西向东，在低纬由东向西，分别与中纬度西风带和热带东风带一致，经向输送在夏季由南半球向北半球输送，冬季则刚好相反，就全年来说水汽也是从南半球向北半球输送。南北半球副热带地区是大气水汽源，热带和中高纬是大气水汽汇，夏季中国大部分地区也是水汽汇。讨论了中国夏季3类雨型与异常水汽输送的关系，结果表明中间型雨带对应中国东部有一支东北异常水汽输送和另一支西南异常输送在长江流域辐合；南方型雨带对应一支东北异常输送和另一支来自西太平洋副高西北侧的西南异常输送在华南辐合，北方型雨带对应中纬度西风异常输送与副高西北侧的西南异常常输送在华北辐合。

Features of Water Vapor Transfer by Summer Monsoon and Their Relations to Rainfall Anomalies over China

The characteristics of summer water vapor transfer are studied by using the NCEP/NCAR reanalysis data from 1958 to 1998. The results show that the zonal vapor transfer is from west to east in middle-high latitudes and from east to west in low latitudes in the both hemispheres.The meridional vapor transfer is from the southern hemisphere to the northern hemisphere in summer and vice versa in winter. The net vapor transfer is also from the southern hemisphere to the northern hemisphere for annual average.Subtropical areas in the both hemispheres are the sources of water vapor, and the eqautor and middle-high latitudes are the sinks. The three rain-bands over China in summer correspond to three different types of the convergence of anomalous water vapor transfer.