南疆夏季降水异常的环流和青藏高原地表潜热通量特征分析

利用1980—2004年NCEP/DOE新再分析月平均资料及我国225个测站1980—2004年月降水量资料,通过诊断分析,研究了南疆夏季降水异常的环流和高原地表潜热通量特征。结果表明:南疆夏季降水偏少年,南亚高压西部偏强,西风急流位置偏北,500 hPa中高纬环流经向度减弱,伊朗高压偏北、偏东,西太平洋副热带高压偏西、偏南;降水偏多年则相反。南疆夏季降水偏少年,高原北部和南疆地区为下沉的垂直环流距平,Ferrell环流增强;降水偏多年则相反。南疆夏季降水偏少年和偏多年的前期冬春季开始孟加拉湾、青藏高原和南疆地区地表潜热通量具有相反的变化,南疆夏季降水与高原北部地表潜热通量呈显著正相关,与南部地表潜热通量呈反相关关系。

Surface Latent Heat Flux Characteristics over Tibetan Plateau and Circulations of Summer Precipitation Anomalies in South Xinjiang

The surface latent heat flux characteristics over Tibetan Plateau and circulations of summer rainfall anomalies in South Xinjiang are diagnostically investigated using the NCEP/DOE reanalysis data and the precipitation data of 225 stations in China from 1980 to 2004.It has been found that west(east) south Asia high is stronger than normal,westerly jet tends to north(south),Iran high moves to north and east(south and west),and western Pacific subtropical high moves to south(north) in drought(flood) year of South Xinjiang.There exits a vertical circulation with descending(ascending) motion anomaly over North Tibetan Plateau and South Xinjiang,and Ferrell circulation strengthens(weakens) in drought(flood) year of Xinjiang.From winter-spring to summer the latent heat variations over Bengal Bay,Tibetan Plateau and South Xinjiang are reverse between drought and flood years of South Xinjiang.There is obvious positive correlation between summer rainfall in South Xinjiang and latent heat over North Plateau.