不同太平洋年代际振荡和ENSO位相下大气水分收支变化对北半球冬季太平洋蒸发量的影响  

Effects of Moisture Budget Changes on Pacific Evaporation Associated with Pacific Decadal Oscillation and ENSO in Boreal Winter

作　　者：韩子轩 苏涛 支蓉[3] 封国林[3,2] 

机构地区：[1]兰州大学大气科学学院,兰州730000 [2]扬州大学物理科学与技术学院,扬州225002 [3]国家气候中心,北京100081

出　　处：《大气科学》2017年第6期1316-1331,共16页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金项目41530531;41375078;41575074;国家重点基础研究发展计划(973计划)项目2013CB430204~~

摘　　要：本文利用OAFlux资料研究了1958~2015年北半球冬季太平洋蒸发量在不同厄尔尼诺—南方涛动(ENSO)和太平洋年代际振荡(PDO)位相下的分布特征,并从水汽收支的角度分析了蒸发量异常的成因,结果表明:ENSO主要影响热带东太平洋、副热带西北太平洋和中纬度北太平洋中部的蒸发量。El Ni?o(La Ni?a)时水汽在北太平洋中部异常辐散(辐合),有利于当地大气水汽含量减小(增大),造成蒸发量增大(减小);副热带西北太平洋异常的水汽辐合(辐散)有利于蒸发量减小(增大);除此以外,蒸发量在热带东太平洋蒸发量增大(减小)则主要是降水量增大(减小)导致。与此同时,ENSO对上述海区蒸发量的影响还受到PDO的调控,当PDO处于暖(冷)位相时,El Ni?o(La Ni?a)造成蒸发量异常程度在中纬度北太平洋中部显著增大,这主要是由降水量增大(减小)引起的大气水汽含量减小(增大)所致,此时对应着风暴轴异常增大(减小);当PDO处于冷(暖)位相时,El Ni?o(La Ni?a)造成的蒸发量异常程度在副热带西北太平洋和热带东太平洋显著增大,而这与湿度变化引起的水汽平流异常程度增大紧密相关。This study assesses the influence of El Nino-Southern Oscillation（ENSO） and Pacific decadal oscillation（PDO） on the distribution of the Pacific evaporation anomaly in boreal winter during 1958-2015 by using Objectively Analyzed air-sea Fluxes（OAFlux） data. Furthermore, we also examine contributions of individual water budget terms in the moisture balance equation to the evaporation anomaly. The results show that the winter evaporation over the eastern tropical Pacific, the subtropical northwestern Pacific, and central northern Pacific are significantly influenced by ENSO. The water vapor is anomalously divergent（convergent） over the central northern Pacific during El Nino（La Nina）, which increases（decreases） the atmospheric water vapor content and enhances（reduces） evaporation. However, the anomalous water vapor convergence（divergence） leads to evaporation decrease（increase） over the subtropical northwestern Pacific. Besides, the increase（decrease） in rainfall results in evaporation increase（decrease） over the eastern tropical Pacific. Meanwhile, this relationship between ENSO and evaporation anomaly is not stationary over those areas and can be modulated by PDO. When El Nino（La Nina） is accompanied with warm（cold） PDO phase, the increase（decrease） in evaporation obvious intensifies over the central northern Pacific mainly due to the increased（decreased） atmospheric water vapor content caused by the increase（decrease） in rainfall, and the storm track is abnormally stronger（weaker）. When El Nino（La Nina） is accompanied with cold（warm） PDO phase, the decrease（increase） in obviously intensifies over the subtropical northwestern Pacific and tropical eastern Pacific, which is related to the enhancement of anomalous moisture advection caused by humidity changes.

关 键 词：太平洋年代际振荡(PDO) 厄尔尼诺—南方涛动(ENSO) 太平洋冬季蒸发量 水汽收支方程 风暴轴 

分 类 号：P467[天文地球—大气科学及气象学]