2015/2016超强厄尔尼诺期间非线性水汽平流对中南半岛4月降水异常的影响  

Influence of Nonlinear Moisture Advection on April Precipitation Anomalies over Indochina Peninsula during 2015/2016 Super El Niño

作　　者：邬钰嫣 葛非[1] 孙雪榕 金正睿 林芷叶 WU Yuyan;GE Fei;SUN Xuerong;JIN Zhengrui;LIN Zhiye(College of Atmospheric Sciences,Chengdu University of Information Technology/Sichuan Key Laboratory of Plateau Atmosphere and Environment,Chengdu 610225,Sichuan,China)

机构地区：[1]成都信息工程大学大气科学学院,四川成都610225

出　　处：《高原气象》2024年第3期711-722,共12页Plateau Meteorology

基　　金：国家自然科学基金项目(42375047,U20A2097);四川省自然科学基金项目(24NSFSC0324);高原与盆地暴雨旱涝灾害四川省重点实验室开放研究基金项目(SZKT202304);成都信息工程大学青年科技创新计划项目(KYQN202201)。

摘　　要：由厄尔尼诺事件引起的极端天气气候事件对社会经济与人民生命财产安全有着重要影响。2014-2016年发生的超强厄尔尼诺事件,使得全球许多地区极端天气和气候事件频发。本文关注了中南半岛区域,利用逐月海温、降水、风场、比湿等观测和再分析资料,从环流和水汽输送异常的角度出发,探讨了超强厄尔尼诺事件背景下2016年4月中南半岛降水异常偏少的可能原因。结果表明,2016年4月,在发展强盛的西北太平洋异常反气旋和副热带高压的控制下,中南半岛上空出现异常下沉气流,不利于水汽辐合产生降水。进一步通过动力诊断分析发现,Nino3.4指数与赤道东印度洋和赤道西太平洋之间纬向海温梯度(zonal gradient of SST anomalies, GSSTA)的乘积能很好地指示此次超强厄尔尼诺事件,且中南半岛上空非线性水汽平流的调制作用是造成此区域4月降水异常偏少的重要原因。2015/2016厄尔尼诺事件期间,西北太平洋异常反气旋的南侧东风与GSSTA“引导”的异常西风水汽输送相互“冲突”,削弱了太平洋和孟加拉湾对中南半岛的水汽输送。中南半岛上空大部分水汽呈现出南少北多,东高西低的模态,水汽辐散,不利于降水的形成。2016年4月,在孟加拉湾异常反气旋和西北太平洋异常反气旋的共同作用下,中南半岛对流受到抑制,暖湿气流在异常南风的引导下,向华南输送。Extreme weather and climate events caused by El Niño have significant impacts on socio-economic conditions and the safety of people’s lives and properties.Between 2014 and 2016,a super El Niño event occurred,leading to frequent extreme weather and climate events worldwide.This study focuses on the Indochina Peninsula region and explores the potential reasons for abnormally decreased precipitation in April 2016,against the backdrop of the super El Niño event.The research utilizes monthly observations and reanalysis data of sea temperatures,precipitation,wind fields,and specific humidity to investigate circulation patterns and abnormal moisture transport.The results indicate that in April 2016,the ICP experienced anomalous sinking currents due to the influence of a developing and robust Western North Pacific Anti-Cyclone and subtropical high-pressure systems.These conditions hindered moisture convergence necessary for precipitation formation.Furthermore,through dynamic diagnostic analysis,the study finds that the product of the Nino3.4 index and the zonal gradient of SST anomalies(GSSTA)between the equatorial East Indian Ocean and the equatorial Western Pacific Ocean effectively indicates the super El Niño event.Additionally,the modulation of nonlinear moisture advection over the ICP plays a vital role in the abnormally low precipitation in the region in April.During the 2015/2016 El Niño event,conflicting wind patterns emerged between the easterly winds on the southern side of the WNPAC and the anomalous westerly moisture transport guided by GSSTA.This conflict weakened the moisture transport from the Pacific Ocean and the Bay of Bengal to the ICP.Over the ICP,most of the moisture exhibited a pattern of being less in the south and more in the north,with higher levels in the east and lower in the west.This led to moisture divergence,which was unfavorable for precipitation formation.In summary,this study emphasizes the significant influence of a super El Niño event on extreme weather and climate events,parti

关 键 词：中南半岛 厄尔尼诺 降水异常 环流异常 水汽输送 

分 类 号：P461.2[天文地球—大气科学及气象学]