MJO和AO持续异常对云南干旱的影响研究

Studies on the Influences of Persistent Anomalies of MJO and AO on Drought Appeared in Yunnan

热带季节内振荡和北极涛动的持续异常会对全球大气环流产生影响,同样会对东亚地区的旱涝造成影响。本文针对云南及周边地区近年来频繁出现的极端干旱事件进行了分析。发现当热带大气季节内振荡(MJO)和北极涛动(AO)两者持续异常时,会对云南的降水产生影响。2009/2010秋、冬、春3季连旱就是由MJO和AO出现极端异常(MJO异常不活跃;AO异常偏弱)造成的。2011年云南主汛期极端伏旱的产生则是由于MJO持续不活跃和西太平洋高压脊异常偏北造成的。

The persistent anomalies of Madden-Julian Oscillation（MJO） and Arctic Oscillation（AO） not only have influences on global general circulation,but also have important implications for the drought and flood in eastern Asia.In this paper the frequent extreme drought events appeared in Yunnan Province and its surrounding areas in the past few years are analyzed.The results show that the precipitation in Yunnan would be affected while MJO and AO showed persistent anomalies.The three-season drought in autumn,winter and spring during the period of 2009-2010 was exactly caused by the extreme anomalies of MJO and AO（MJO was inactive while AO was unusually weak）.And the persistent inactivity of MJO and the abnormally northerly location of western Pacific subtropical highs were responsible for the extreme summer drought during main flood season in 2011 of Yunnan.