| DOI: | 10.1007/s00382-015-2665-3
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| Scopus记录号: | 2-s2.0-84959131180
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| 论文题名: | Strong and moderate nonlinear El Niño regimes |
| 作者: | Takahashi K.; Dewitte B.
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| 刊名: | Climate Dynamics
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| ISSN: | 9307575
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| 出版年: | 2016
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| 卷: | 46, 期:2017-05-06 | | 起始页码: | 1627
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| 结束页码: | 1645
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| 语种: | 英语
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| 英文关键词: | Bjerknes feedback
; Eastern Pacific
; El Niño
; ENSO
; GFDL CM2.1
; Nonlinear dynamics
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| 英文摘要: | It has been previously proposed that two El Niño (EN) regimes, strong and moderate, exist but the historical observational record is too short to establish this conclusively. Here, 1200 years of simulations with the GFDL CM2.1 model allowed us to demonstrate their existence in this model and, by showing that the relevant dynamics are also evident in observations, we present a stronger case for their existence in nature. In CM2.1, the robust bimodal probability distribution of equatorial Pacific sea surface temperature (SST) indices during EN peaks provides evidence for the existence of the regimes, which is also supported by a cluster analysis of these same indices. The observations agree with this distribution, with the EN of 1982–1983 and 1997–1998 corresponding to the strong EN regime and all the other observed EN to the moderate regime. The temporal evolution of various indices during the observed strong EN agrees very well with the events in CM2.1, providing further validation of this model as a proxy for nature. The two regimes differ strongly in the magnitude of the eastern Pacific warming but not much in the central Pacific. Observations and model agree in the existence of a finite positive threshold in the SST anomaly above which the zonal wind response to warming is strongly enhanced. Such nonlinearity in the Bjerknes feedback, which increases the growth rate of EN events if they reach sufficiently large amplitude, is very likely the essential mechanism that gives rise to the existence of the two EN regimes. Oceanic nonlinear advection does not appear essential for the onset of strong EN. The threshold nonlinearity could make the EN regimes very sensitive to stochastic forcing. Observations and model agree that the westerly wind stress anomaly in the central equatorial Pacific in late boreal summer has a substantial role determining the EN regime in the following winter and it is suggested that a stochastic component at this time was key for the development of the strong EN towards the end of 1982. © 2015, The Author(s). |
| 资助项目: | CNES, Centre National d’Etudes Spatiales
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| Citation statistics: |
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| 资源类型: | 期刊论文
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/53790
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| Appears in Collections: | 过去全球变化的重建
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作者单位: | Instituto Geofísico del Perú, Lima, Peru; IRD/LEGOS, Toulouse, France
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| Recommended Citation: | |
Takahashi K.,Dewitte B.. Strong and moderate nonlinear El Niño regimes[J]. Climate Dynamics,2016-01-01,46(2017-05-06)
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