Role of Nonlinear Atmospheric Response to SST on the Asymmetric Transition Process of ENSO
Role of Nonlinear Atmospheric Response to SST on the Asymmetric Transition Process of ENSO
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DOI：
10.1175/2008jcli2334.1
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发表时间：
2009
影响因子：
4.9
通讯作者：
M. Ohba;H. Ueda
中科院分区：
文献类型：
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作者：
M. Ohba;H. Ueda
利用观测资料和物理模式分析了大气对海温的非线性响应，探讨了导致El Nino和La Nina事件之间不对称过渡过程的物理过程。ENSO的海气耦合系统能够在弱冷事件中保持长达2年，而相对温暖事件的系统则转变为冷阶段。通过对海洋观测资料的分析，发现在ENSO成熟到衰减阶段，赤道太平洋表层纬向风异常的温跃层变化存在较大差异。大气对ENSO暖相的响应导致北方冬季EP西风带的快速减少，而EP西风带通过产生上升流的海洋开尔文波加速ENSO的转变。然而，寒冷阶段的异常EP东风持续到随后的春季，这往往抵消了从…
Abstract Physical processes that are responsible for the asymmetric transition processes between El Nino and La Nina events are investigated by using observational data and physical models to examine the nonlinear atmospheric response to SST. The air–sea coupled system of ENSO is able to remain in a weak, cold event for up to 2 yr, while the system of a relatively warm event turns into a cold phase. Through analysis of the oceanic observational data, it is found that there is a strong difference in thermocline variations in relation to surface zonal wind anomalies in the equatorial Pacific (EP) during the mature-to-decaying phase of ENSO. The atmospheric response for the warm phase of ENSO causes a rapid reduction of the EP westerlies in boreal winter, which play a role in hastening the following ENSO transition through the generation of upwelling oceanic Kelvin waves. However, the anomalous EP easterlies in the cold phase persist to the subsequent spring, which tends to counteract the turnabout from the ...