大气科学2013，Vol.37Issue(4)：829-840,12.DOI:10.3878/j.issn.1006-9895.2012.12058
对流层低层偏东风对北京局地暴雨的作用
Roles of Low-Level Easterly Winds in the Local Torrential Rains of Beijing
摘要
Abstract
Using data from wind profile radar and automatic surface weather observation stations,and NCEP 1°× 1°analysis data,a comparative analysis of two cases of low-level easterly winds (LLEWs) associated with two local rainstorms in Beijing was performed.The investigation concentrated on the formation mechanism,the features of the vertical structure and thermodynamics,and the role in local rainstorms.The results showed:1) a shallow low-level wind (SLLEW) existed below 500 m with a ground wind speed of about 1 m/s,horizontal scale of about 250 km,and time scale of 12 h,and a deep low-level wind (DLLEW) existed below 3000 m with a ground wind speed of about 4 m/s,horizontal scale greater than 600 km,and time scale longer than 24 h.2) The SLLEW was caused by a sub-synoptic-scale warm vortex generated in the boundary layer,whereas the DLLEW was caused by a synoptic-scale inverted surface warm trough.3) Both the SLLEW and DLLEW were accompanied by high equivalent potential temperature,and their sources were warm moist air masses located east or southeast of Beijing.There was a cold,dry air intrusion over the LLEWs that could result in convective instability.The SLLEW supported a significant local concentration of air with high equivalent potential temperature,and the DLLEW contributed to the transportation of moisture and energy and the formation of stronger low-level wind shear,which was favorable to the development of severe convective storms.4) The SLLEW was consistent with the low-level convergence in time and space,and interacted strongly with the upper divergence,thus acting as a triggering factor; however,the DLLEW could not act as a triggering factor owing to its inconsistency.关键词
对流层低层偏东风/形成机制/结构特征/北京局地暴雨Key words
Easterly wind/ Formation mechanism/ Structural features/ Local rainstorm in Beijing分类
天文与地球科学引用本文复制引用
张文龙,崔晓鹏,王迎春,李青春,黄荣..对流层低层偏东风对北京局地暴雨的作用[J].大气科学,2013,37(4):829-840,12.基金项目
国家自然科学基金资助项目41075047,"十一五"国家科技支撑重点项目2008BAC37B01,中央级公益性科研院所专项IUMKY201002 （）
