2011年长江中下游旱涝急转成因初步分析  

Preliminary Analysis of Sudden Turn of Drought and Flood in the Middle and Lower Reaches of the Yangtze River during 2011

作　　者：李迅[1] 袁东敏[2] 尹志聪[1] 李文静[2] 谢庄[1] 

机构地区：[1]北京市气象局,北京100089 [2]中国气象局华风气象传媒集团,北京100081

出　　处：《气候与环境研究》2014年第1期41-50,共10页Climatic and Environmental Research

基　　金：北京地区气候变化对城市热环境影响评估及气象节能关键技术研究Z090506016609001;铁路(高铁)气象监测预警;预报服务关键技术研究GYHY201306058-X

摘　　要：以2011年1～6月长江中下游“旱涝急转”事件为例，研究了长江中下游旱涝急转与大尺度环流和海温异常的关系，初步得到以下引发旱涝急转的原因：（1）中高纬度大气环流出现快速调整，迅速由强冬季风形势调整为两槽一脊环流形势所控制，进而造成长江中下游由受中高纬度系统控制转变为冷暖空气对峙之地；（2）西太平洋副热带高压位置和强度迅速调整，1～5月来自热带地区的水汽输送条件差，长江中下游地区水汽辐合较常年明显偏弱。6月，水汽输送和收支状况发生根本性转变，长江中下游表现为显著的水汽辐合中心，且明显强于常年；（3）6月青藏高原上空存在显著的气旋性异常环流，利于对流活动发展，受其底部异常西风的影响，对流活动频繁地东传至长江中下游地区，增强了梅雨锋的强度，先后引发了5次强降水过程；（4）前期持续的La Nina事件及其变化通过影响Walker环流、西太平洋副热带高压等大气环流系统，为旱涝急转事件的发生提供了有利的背景条件。Using the sudden turn of drought and flood （STDF） in the middle and lower reaches of the Yangtze River during 2011, as an example, the relation between the STDF and circulation and sea surface temperature （SST） is studied. The reasons for the STDF are the following. （1） The atmospheric circulation quickly adjusted from strong winter monsoon to the station, called two troughs and one ridge. （2） The location and strength of the western Pacific subtropical high also changed quickly. The convergence of water vapor transport was obviously weaker in the middle and lower reaches of the Yangtze River from January to May. In June, the water vapor transport and budget changed and there was an obviously stronger center of water vapor convergence in the middle and lower reaches of the Yangtze River. （3） Because of the cyclonic anomalous circulation over the Tibetan Plateau, the convection is active and frequently moves to the middle and lower reaches of the Yangtze River. This convection strengthened the Mei-yu front and triggered rainfall five times. （4） The persistent La Nina event and its variations created favorable background conditions by influencing the Walker circulation, the western Pacific subtropical high, and so on.

关 键 词：旱涝急转 副热带高压 水汽通量 青藏高原 LA NINA 

分 类 号：P461.2[天文地球—大气科学及气象学]