The very strong coastal El Niño in 1925 in the far-eastern Pacific
The very strong coastal El Niño in 1925 in the far-eastern Pacific
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1925年远东太平洋沿岸出现非常强烈的厄尔尼诺现象
DOI：
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发表时间：
2019
期刊：
影响因子：
4.6
通讯作者：
Alejandra Martínez
中科院分区：
文献类型：
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作者：
Ken Takahashi;Alejandra Martínez
1925年厄尔尼诺现象是世纪第三大厄尔尼诺现象，其影响与1925年2月至4月秘鲁北方沿海和厄瓜多尔的暴雨和洪水有关。在这项研究中，我们收集和综合了大量的现场观测，从现代的角度提供了一个新的评估这一事件。与1982-1983年和1997-1998年的极端事件相比，1925年初的这场非常强烈的“沿海厄尔尼诺”的特点是FEP的温暖条件，但太平洋中部其他地方的凉爽条件。水文和验潮数据表明，下降的赤道开尔文波在其启动的作用不大。相反，船舶数据表明赤道上空突然出现强北风，赤道南/北的热带辐合区（ITCZ）增强/减弱。观测结果表明，缺乏外部大气强迫的巴拿马间隙急流和南太平洋反气旋，并建议耦合的海洋-大气反馈动力学与ITCZ，偏北风，南北SST不对称的FEP导致增强的季节性循环，产生这个EN事件。我们建议，在赤道太平洋中西部的寒冷条件下，通过其对FEP的遥相关效应，有助于不稳定的ITCZ和增强纬向海-气反馈，以及帮助产生非常强的沿海降雨。5°S处的皮乌拉河记录与FEP和赤道太平洋中西部的SST差（一个稳定度代用指标）之间的非线性关系表明了这一点。总之，有两种类型的EN事件在FEP中具有非常强的影响，两者显然与非线性对流反馈有关，但具有非常不同的动力学：非常强的温暖ENSO事件，如1982-1983年和1997-1998年，以及非常强的“沿海”EN事件，如1925年。
The 1925 El Niño (EN) event was the third strongest in the twentieth century according to its impacts in the far-eastern Pacific (FEP) associated with severe rainfall and flooding in coastal northern Peru and Ecuador in February–April 1925. In this study we gathered and synthesised a large diversity of in situ observations to provide a new assessment of this event from a modern perspective. In contrast to the extreme 1982–1983 and 1997–1998 events, this very strong “coastal El Niño” in early 1925 was characterised by warm conditions in the FEP, but cool conditions elsewhere in the central Pacific. Hydrographic and tide-gauge data indicate that downwelling equatorial Kelvin waves had little role in its initiation. Instead, ship data indicate an abrupt onset of strong northerly winds across the equator and the strengthening/weakening of the intertropical convergence zones (ITCZ) south/north of the equator. Observations indicate lack of external atmospheric forcing by the Panama gap jet and the south Pacific anticyclone and suggest that the coupled ocean–atmosphere feedback dynamics associated with the ITCZs, northerly winds, and the north–south SST asymmetry in the FEP lead to the enhancement of the seasonal cycle that produced this EN event. We propose that the cold conditions in the western-central equatorial Pacific, through its teleconnection effects on the FEP, helped destabilize the ITCZ and enhanced the meridional ocean–atmosphere feedback, as well as helping produce the very strong coastal rainfall. This is indicated by the nonlinear relation between the Piura river record at 5°S and the SST difference between the FEP and the western-central equatorial Pacific, a stability proxy. In summary, there are two types of EN events with very strong impacts in the FEP, both apparently associated with nonlinear convective feedbacks but with very different dynamics: the very strong warm ENSO events like 1982–1983 and 1997–1998, and the very strong “coastal” EN events like 1925.