2011年春夏季长江中下游旱涝急转可能成因  

Possible causes of abrupt turning from drought to flooding in the middle and lower reaches of Yangtze River valley during spring to summer of 2011

作　　者：李明[1] 祝从文[1] 庞轶舒 

机构地区：[1]中国气象科学研究院气候系统研究所,北京100081

出　　处：《气象与环境学报》2014年第4期70-78,共9页Journal of Meteorology and Environment

基　　金：国家自然科学基金(40921003);中国气象科学研究院基本科研业务项目(Z2010Z001;Z2010Z003)共同资助

摘　　要：利用1980—2011年观测的降水和美国NCEP/NCAR大气再分析等资料,采用经验正交分解(EOF)和线性回归等统计方法,讨论了2011年发生在长江中下游地区春夏旱涝急转的成因。结果表明:2011年1—5月持续的La Nia事件导致西北太平洋副热带高压位置位于125°E以东,西北太平洋副热带高压西北侧的西南风伴随的水汽通量无法达到长江流域,从而导致2011年长江流域1—5月的持续性干旱现象。伴随La Nia的减弱,6月青藏高原的感热明显增强,诱发西北太平洋副热带高压自东向西北方向移动至110°E,引导西南风水汽向长江流域输送,而青藏高原对流的加强和向东移动与来自西北太平洋副热带高压西北侧的西南气流在长江中下游地区汇合,导致6月长江中下游地区降水的急剧增加,从而形成了2011年长江中下游地区春夏季的旱涝急转。Based on observed precipitation and the NCEP/NCAR reanalyzed datasets from 1980 to 2011,possible causes of abrupt turning from drought to flooding in the middle and lower reaches of Yangtze River valley （YRV） region during spring to early summer of 20 1 1 were discussed using methods of an EOF and a linear regression a-nalysis.The results indicate that the persistent La Nina events during January to May of 2011 maintain the 125°E eastward shift of western North Pacific subtropical high （WNPSH）,thus the southwesterly moisture flux fails to reach the YRV region,which leads to the persistent drought events from January to May of 20 1 1 .However,sensi-tive heating flux enhances in the Tibetan Plateau （TP）with the decaying of La Nin？a in June,which induces a westward shift of WNPSH moving to 1 10°E from east to northwest and makes water vapor from southwesterly wind transporting to the YRV.Convection from the TP enhances and moves to east,and it meets southwest air flow from the northwest side of WNPSH in the middle and lower reaches of the YRV,which leads to increase precipita-tion sharply,and then it forms abrupt turning from drought to flooding in 2011 .

关 键 词：旱涝急转 LA NINA 感热 

分 类 号：P466[天文地球—大气科学及气象学]