西北地区夏季降水异常及其水汽输送和环流特征分析

Analysis of Summer Precipitation Anomaly and the Feature of Water Vapor Transport and Circulation in Northwest China

利用NCEP/NCAR 1951～2000年共50 a的再分析资料及我国西北地区内31个代表站的降水资料,对西北地区近50 a来夏季降水异常的时空特征、环流形势及水汽输送进行了研究。分析发现,西北地区夏季降水异常与东部沿海地区的降水呈反位相分布,说明西北地区和东部沿海地区的降水影响系统不同,影响时期不一致。分析结果表明,影响西北地区夏季多、少雨年的相关区域环流特征和水汽输送特征有显著差异。

Summer precipitation anomaly and the feature of water vapor transport and circulation in Northwest China are studied by using the NCEP/NCAR reanalysis data from 1951 to 2000 and rainfall observations of 31 representative stations in Northwest China. It is found that the phases between precipitation anomaly in Northwest China and that in east coast of China are opposite, and the influencing systems and periods to summer rainfall are different between those two aeras. Results show that the circulation and water vapor transport of dry years in the related areas are significantly different from those of wet years.