doi:  10.3878/j.issn.1006-9895.1810.17229
冬季两类ENSO的海气环流模态分析

Model analysis on ocean-atmosphere circulation of two types of ENSO in winter
摘要点击 87  全文点击 5  投稿时间:2017-09-05  修订日期:2018-01-14
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基金:  科技部全球变化及应对重点专项,地球系统模式研发、预测和预估
中文关键词:  东部型ENSO,中部型ENSO,海气环流,复EOF分解
英文关键词:  EP-ENSO, CP-ENSO, ocean-atmosphere circulation, CEOF
     
作者中文名作者英文名单位
张东凌ZHANG Dongling中科院大气物理研究所
卢姁Lu Xu32021部队
引用:张东凌,卢姁.2019.冬季两类ENSO的海气环流模态分析[J].大气科学
Citation:ZHANG Dongling,Lu Xu.2019.Model analysis on ocean-atmosphere circulation of two types of ENSO in winter[J].Chinese Journal of Atmospheric Sciences (in Chinese)
中文摘要:
      本文对1950-2001年1月份的大气风场和大洋流场做了联合复EOF分解,用以探讨冬季两类ENSO的海气环流及耦合情况,所得结果主要有:该分解第一、二模态空间场分别相应于东部型、中部型ENSO,前者在赤道太平洋东部和中部都有海温动力异常,并以东部异常最强,后者仅在中部存在此异常,两模态的时间系数都与ENSO有很好相关,为此第一、二模态可分别称为东部型、中部型ENSO 模态。东部型ENSO模态具有3-6年的年际变化和13-14年及22年的年代际变化,中部型则有明显的7年年际变化和12、17、23年的年代际变化,两者中约22、13年的周期分别与冬季北太平洋主、次要气候模态即PDO、NPGO的周期相同。东、中部型El Ni?o期间,沃克环流上升支分别从印尼东移至赤道西、中太平洋,并有所减弱;南、北支哈得莱环流则分别位于日界线以东及该线附近,且均有所加强,从而使南、北太平洋副热带高压偏强;而在5°S的南美沿岸则分别有垂直运动上升和下沉异常。在海气耦合上,两类ENSO模态在赤道中太平洋均存在西风异常与海洋赤道Kelvin波和Rossby波的波包解耦合,而海温动力异常对大气的影响则都起到负反馈作用,从而有利于ENSO的维持和稳定。ENSO对西太平洋低纬冬季风有明显影响,El Ni?o期间该冬季风偏弱,La Ni?a期间则偏强;中部型ENSO期间该冬季风冷涌前锋位置要较东部型的略有偏北。
Abstract:
      In this paper, combined complex EOF(CEOF)analysis is made for the atmospheric wind field and ocean flow field in January from 1950 to 2001,in order to understand two types of ENSO in coupled ocean-atmosphere circulation in winter. The results are: The first mode and the second mode respectively correspond to Eastern Pacific type of ENSO (EP-ENSO) and the Central Pacific type of ENSO (CP-ENSO). The former shows there has sea surface temperature (SST) anomaly in eastern and central equatorial Pacific, and the eastern anomaly is stronger; the latter shows there has SST anomaly only in central equatorial Pacific. Their temporal coefficients are closely related to ENSO. So they can be named as EP-ENSO mode and CP-ENSO mode on wind - current field respectively. The EP-ENSO mode has distinct interannual and interdecadal variations from 3 to 6, and 13 to 14 years. The CP-ENSO mode has distinct interannual and interdecadal variations for 7, 12 and 17 years. The change period of 13 years is similar to the NPGO period of winter climate mode in north pacific. During the Eastern and Central Pacific type of El Ni?o, the ascending branch of Walker Circulation shifts eastwardly from Indonesia to western or central equatorial Pacific, and the intensity weakens; the south and north branches of Hadley Circulation are east of or near the international date line, and the intensity enhances; it causes the subtropical high to be stronger; along coast of South America near 5°S, there are anomalies of updraft and downdraft. For two types of ENSO modes, there are westerly anomalies and wave packet solutions of Kelvin wave and Rossby wave near central equatorial Pacific. Sea Temperature kinetic anomaly has a negative feedback effect on atmospheric circulation, which is propitious to the maintenance and stability of ENSO.
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