摘要
利用台站观测和NCEP/NCAR大气再分析等资料,通过与历史同期降水事件比较,分析了2009年冬季发生在我国新疆阿勒泰地区持续的水汽和环流异常特征以及北极涛动(Arctic Oscillation,AO)和ENSO现象对该地区持续性暴雪的影响。结果发现,位于贝加尔湖以西的对流层持续性异常冷性低槽活动是影响2009年冬季新疆北部持续性暴雪的重要环流系统,该异常低槽导致冷空气南下路径偏西,并与来自里海的水汽输送在新疆北部地区交汇,导致了持续性寒潮天气和暴雪的发生。其中,贝加尔湖地区的异常低槽的维持与AO指数异常偏弱密切相关,当AO指数处于负位相时,贝加尔湖一带位势高度出现负异常,北半球盛行经向环流异常,有利于乌拉尔山阻塞高压的维持和冷空气沿贝加尔湖向南侵袭,导致新疆北部持续性寒潮和大暴雪天气发生。分析冬季ENSO事件对新疆北部的影响中发现,El Ni^no年冬季,同期西太平洋副热带高压偏强偏北,低纬度海洋水汽大多沿着副高边缘向东南输送,其北上分量无法到达新疆地区,因此El Ni^no对新疆北部的持续性大暴雪的影响并不明显。
The anomalies of moisture flux and atmospheric circulations linked to the subsequent snowstorms occurring in Altay area of Xinjiang during winter 2009 are discussed on the basis of station-observed and NCAR/NCEP reanalyzed data sets,and the possible causes associated with ENSO and Arctic Oscillation（AO） are addressed in the framework of historical analog analysis.Results suggest the enhanced anomalous cold trough in the west of Lake Baikal is a critical circulation system,and its maintenance resulted in the west cold surge moving southward,meeting the southwest warm and wet air coming from the Caspian Sea in North Xinjiang,and caused the successive snowstorms.Correlation analysis suggests that the enhanced anomalous cold trough over the west of Lake Baikal is closely related to the weakened AO index.In negative AO index phase,the 500-hPa geopotential height around Lake Baikal decreases,a meridional circulation anomalies pattern prevails in the Northern Hemisphere,which maintained the Ural blocking high and gave rise to the southward moving clod surge along the west of Lake Baikal,and results in the successive cold waves and snowstorms in the north of Xinjiang.Analysis suggests that during the El Nin^o year,the enhanced western North Pacific subtropical high results in the southeast moisture flux,but the northward component could not arrive in North Xinjiang,therefore the El Nin^o event possibly has little benefit to the successive snowstorms in this area.
出处
《大气科学》
CSCD
北大核心
2011年第5期833-846,共14页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目40921003
公益性行业(气象)科研专项GYHY200906017
中国气象科学研究院基本科研业务项目2010Z001
2010Z003
关键词
2009年冬季
新疆暴雪
环流异常
成因分析
winter 2009
snowstorms in Xinjiang
circulation anomalies
causes analysis
