What Controls the Duration of El Niño and La Niña Events?
What Controls the Duration of El Niño and La Niña Events?
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DOI：
10.1175/jcli-d-18-0681.1
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发表时间：
2018-01
影响因子：
4.9
通讯作者：
Xiandu Wu
中科院分区：
文献类型：
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作者：
Xiandu Wu
厄尔尼诺和拉尼娜的时间演变在不同事件之间有很大差异。为了了解控制厄尔尼诺和拉尼娜事件持续时间的动力学过程，分析了一套观测数据和社区地球系统模型第1版的长期控制模拟。观测和模式分析都表明，厄尔尼诺现象的持续时间受到其发生时间的强烈影响。发展较早的厄尔尼诺现象往往在成熟阶段后很快结束，因为延迟的负海洋反馈提前到来，热带大西洋和印度洋对热带太平洋变暖的快速调整。另一方面，拉尼娜事件的持续时间受到先前温暖事件幅度的强烈影响。拉尼娜事件之前有一个强烈的温暖事件往往会持续到第二年，因为大量的赤道海洋热含量的初始排放和热带大西洋和印度洋延迟调整热带太平洋冷却。对于厄尔尼诺和拉尼娜，海盆间海表温度（SST）的调整减小了热带太平洋SST的异常梯度，减弱了赤道西太平洋海面风场的异常，加速了事件的结束。厄尔尼诺-南方涛动动力学之外的其他因素，如热带大西洋和印度洋的耦合变率以及北太平洋上空的大气变率，也有助于事件持续时间的多样性。
The temporal evolution of El Niño and La Niña varies greatly from event to event. To understand the dynamical processes controlling the duration of El Niño and La Niña events, a suite of observational data and a long control simulation of the Community Earth System Model, version 1, are analyzed. Both observational and model analyses show that the duration of El Niño is strongly affected by the timing of onset. El Niño events that develop early tend to terminate quickly after the mature phase because of the early arrival of delayed negative oceanic feedback and fast adjustments of the tropical Atlantic and Indian Oceans to the tropical Pacific Ocean warming. The duration of La Niña events is, on the other hand, strongly influenced by the amplitude of preceding warm events. La Niña events preceded by a strong warm event tend to persist into the second year because of large initial discharge of the equatorial oceanic heat content and delayed adjustments of the tropical Atlantic and Indian Oceans to the tropical Pacific cooling. For both El Niño and La Niña, the interbasin sea surface temperature (SST) adjustments reduce the anomalous SST gradient toward the tropical Pacific and weaken surface wind anomalies over the western equatorial Pacific, hastening the event termination. Other factors external to the dynamics of El Niño–Southern Oscillation, such as coupled variability in the tropical Atlantic and Indian Oceans and atmospheric variability over the North Pacific, also contribute to the diversity of event duration.