2011年夏季气候异常及主要异常事件成因分析  

Analysis of Climate Anomaly and Causation in Summer 2011

作　　者：王遵娅[1] 任福民[1] 孙冷[1] 柳艳菊[1] 王朋岭[1] 唐进跃[1] 王东阡[1] 李多[1] 

机构地区：[1]国家气候中心,北京100081

出　　处：《气象》2012年第4期448-455,共8页Meteorological Monthly

基　　金：国家自然科学基金(40905036);国家科技支撑计划(2007BAC29B06)共同资助

摘　　要：本文对2011年夏季的中国气候及大气环流异常特征进行分析,发现我国总体气温偏高,降水偏少。西北西部、华北南部、江淮至江南一带,西南地区东部等地出现了阶段性的较大范围极端高温天气过程。西南地区东部和广西等地出现严重干旱;而长江下游地区降水显著偏多。进一步对中国气候异常事件的成因分析表明:异常高压的长期维持,孟加拉湾的向北水汽输送偏弱及西太平洋副热带高压位置偏东使其西侧的东南和偏南水汽输送对我国西南地区影响小是导致西南地区严重干旱的大气环流因素;2010年秋季出现的中部型拉尼娜事件可能是西南干旱的一个重要外强迫条件。2011年夏季亚洲极涡偏弱偏小,欧亚中高纬地区经向环流偏强,有利于冷空气南下;同时,中纬度西太平洋地区海温持续偏低而激发反气旋性环流产生,造成西太平洋副高偏大偏强,冷暖气流在长江下游地区交汇造成降水显著偏多。Climate characters were analyzed over China in summer 2011. It was found that, the mean tem- perature was higher than and the precipitation was less than normal in China. High temperature extremes were observed in extensive regions including western Northwest China, southern North China, theYangtze and Huaihe River Valley, areas to the south of the Yangtze River, eastern Southwest China, and so on during some periods. Severe persistent droughts occurred in the eastern part of Southwest China, but significantly more rainfalls than normal occurred in the Lower Reaches of the Yangtze River. Possiblecauses for droughts in eastern Southwest China and more precipitation in the Lower Reaches of the Yangtze River were discussed further. Results showed that continuous anomalous high pressure over Southwest China, weak water vapor transports from the Bay of Bengal and the further east location of thewestern Pacific subtropical high directly caused the Southwest China drought. And the central type La Ni- na event developing from autumn 2011 may be an important external forcing impacting the drought in Southwest China. The negative phase of AO maintained during summer 2011, and then the polar vortexwas weaker than normal, which was advantageous for southward shift of cold airs to affect China. At the same time, the anomalous anti-cyclone circulation responding to the negative $STA in the mid-latitude West Pacific intensified the western Pacific subtropical high. And then the northward water vapor trans-port was stronger than normal. Cold airs met with the moist and warm water vapor and then caused abun- dant rainfalls in the Lower Reaches of the Yangtze River.

关 键 词：气候异常 西南干旱 长江下游多雨 成因分析 

分 类 号：P467[天文地球—大气科学及气象学]