两个典型ENSO季节演变模态及其与我国东部降水的联系  

Two Typical ENSO Seasonal Evolution Modes and Their Relations with Rainfall over Eastern China

作　　者：宗海锋[1] 

机构地区：[1]中国科学院大气物理研究所国际气候与环境科学中心,北京100029

出　　处：《大气科学》2017年第6期1264-1283,共20页Chinese Journal of Atmospheric Sciences

基　　金：国家科技支撑计划项目2015BAC03B03;国家自然科学基金项目41375055~~

摘　　要：本文根据1950~2014年月平均海温和大气环流资料以及中国160站降水等资料,利用扩展经验正交函数(EEOF)分析、相关分析以及合成分析等方法,分析了太平洋海温季节演变的主导模态,并探讨了各模态与中国东部降水和东亚环流季节变异的关系及其联系的物理过程。结果表明,ENSO(El Ni?o/Southern Oscillation)季节演变存在2个主导模态,包含4种类型:El Ni?o持续型、La Ni?a持续型、La Ni?a转El Ni?o型和El Ni?o转La Ni?a型。发现不同模态和类型的ENSO季节变化过程我国东部降水距平的分布和强度都有明显差异。El Ni?o持续型和El Ni?o转La Ni?a型,冬春季和初夏均处在El Ni?o背景下,降水异常分布存在一定共性,但盛夏和秋季分别受El Ni?o和La Ni?a影响,降水异常分布差异十分明显,前者雨带北跳慢、位置偏南而后者雨带北跳快、位置偏北。La Ni?a持续型和La Ni?a转El Ni?o型也是如此,冬春季和初夏降水异常分布大致相似,但盛夏和秋季分别受La Ni?a和El Ni?o影响,前者雨带北跳快、位置偏北而后者雨带北跳慢、位置偏南。因此,利用ENSO做我国降水的气候预测时,不能只着眼于前期冬季El Ni?o或La Ni?a事件,还应考虑其未来演变所属的可能模态和类型。对他们之间联系的物理过程分析表明,不同ENSO季节演变模态和类型主要通过影响西太平洋副热带高压以及西风带经向型/纬向型环流调整及伴随的低纬暖湿水汽输送以及中高纬冷空气活动变化来影响我国东部降水。其中,西太平洋菲律宾群岛附近异常反气旋(或气旋)、赤道Walker环流和北半球Hadley环流分别是联系ENSO与西太平洋副热带高压活动和东亚西风带经向型/纬向型环流的重要环节。The author analyzed the main seasonal evolution modes of the Pacific sea surface temperature and their relations with the seasonal evolution of rainfall over eastern China and the atmospheric circulation over East Asia as well as the related physical processes by applying extended empirical orthogonal function（EEOF） analysis, correlation analysis, and composition analysis, etc, using the datasets of monthly sea surface temperature, atmospheric circulation, and monthly rainfall of 160 stations in China. The main results show that there are two dominant modes in the seasonal evolution of ENSO（El Nino/Southern Oscillation）, including four types（El Nino persisting, La Nina persisting, La Nina switching to El Nino, and El Nino switching to La Nina）. Obvious differences in the distribution and intensity of rainfall anomalies over eastern China are found between different modes and types of seasonal evolution of ENSO. For the types ENSO persisting and El Nino switching to La Nina, the distributions of rainfall anomalies are somewhat similar because both types occur under the background of El Nino in winter, spring, and early summer. But the distributions of rainfall anomalies are remarkably different in midsummer and autumn because they are under the influences of El Nino and La Nina, respectively. The rainbelt jumps northward slowly and is located further south for the former, whereas it jumps northward quickly and is located further north for the latter. The similar situation can be found for the types La Nina persisting and La Nina switching to El Nino, and the distributions of rainfall anomalies are somewhat similar in winter, spring, and early summer. But the rainbelt moves northward quickly and is located further north for the type La Nina persisting, while the opposite is true for the type La Nina switching to El Nino in midsummer and autumn. This is because rainfall is under the impacts of El Nino and La Nina respectively during that period. Therefore, not only the early signals of ENSO but also the

关 键 词：ENSO 季节演变 模态和类型 中国东部降水 

分 类 号：P467[天文地球—大气科学及气象学]