Joint impact of North and South Pacific extratropical atmospheric variability on the onset of ENSO events
Joint impact of North and South Pacific extratropical atmospheric variability on the onset of ENSO events
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DOI：
10.1002/2016jd025502
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发表时间：
2017-01
期刊：
影响因子：
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通讯作者：
R. Ding;Jianping Li;Y. Tseng;Cheng Sun;F. Xie
中科院分区：
文献类型：
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作者：
R. Ding;Jianping Li;Y. Tseng;Cheng Sun;F. Xie
以往的研究表明，北半球冬季南北太平洋副热带和热带外海表气压（SLP）异常与下一个冬季的厄尔尼诺-南方涛动（ENSO）状态有着显著的联系。在这里，我们使用的观测数据和模式模拟表明，北方冬季北太平洋SLP异常启动ENSO事件一年后的能力可能强烈依赖于同时南太平洋SLP异常的状态，反之亦然。当冬季北太平洋SLP异常与同期南太平洋SLP异常的符号相反时，北太平洋或南太平洋SLP异常与随后ENSO状态的相关性变弱，ENSO事件的强度也趋于减弱。一个可能的原因是，当北半球冬季南北太平洋SLP异常具有相反的符号时，在接下来的北半球夏季，赤道太平洋中西部的西风异常被前期南北太平洋SLP异常之间的干扰大大减弱，从而不利于ENSO事件的发展。进一步的分析表明，南北太平洋前兆信号的组合可能有助于提高ENSO预测能力。
Previous studies have indicated that boreal winter subtropical and extratropical sea surface pressure (SLP) anomalies over both the North and South Pacific are significantly related to the El Niño–Southern Oscillation (ENSO) state in the following boreal winter. Here we use observational data and model simulations to show that the ability of the boreal winter North Pacific SLP anomalies to initiate ENSO events a year later may strongly depend on the state of the simultaneous South Pacific SLP anomalies and vice versa. When the boreal winter North Pacific SLP anomalies are of the opposite sign to the simultaneous South Pacific anomalies, the correlation of the North or South Pacific anomalies with the following ENSO state becomes much weaker, and the strength of the ENSO events also tends to be weaker. One possible reason for this is that when the boreal winter North and South Pacific SLP anomalies have the opposite sign, the westerly anomalies over the western‐central equatorial Pacific during the following boreal summer are greatly reduced by the interference between the antecedent North and South Pacific SLP anomalies, thereby not favoring the development of ENSO events. Further analysis indicates that a combination of North and South Pacific precursor signals may serve to enhance the ENSO prediction skill.