Collaborative Research: Westerly Wind Bursts: El Nino Southern Oscillation's (ENSO) Driver or Slave?

西风暴发(WWB)事件在厄尔尼诺南方涛动(ENSO)的动力学过程中起着重要作用。这些事件通常被认为是与大尺度ENSO动力学无关和外部的随机强迫。然而，有迹象表明，这些事件的发生及其特征受到大尺度SST结构的影响，因此也受到ENSO的影响。这项研究将探索WWB事件的时间和其他特征被大尺度SST分布部分调控的可能性的动力学后果。也就是说，这项研究将考察这些事件只有在大尺度SST结构处于特定配置时才发生的极端可能性。例如，当暖池向东延伸超过日期线时。在这种情况下，WWB事件将被视为确定性ENSO动力学的固有部分，而不是外部随机强迫。这项研究将首先分析观测结果，以便尝试建立这种大尺度海温场对WWB事件的时间或特征的可能调节的特征。接下来，我们将使用模型的层次结构来研究大尺度ENSO动力学对WWB事件的这种受调控的切换的影响。模式层次将包括混合耦合模式(与统计大气耦合的海洋环流模式)、中间耦合模式和概念性延迟振荡器模式。这项研究的更广泛的影响包括：如果拟议的研究找到一种方法，在当前的ENSO预测模式中利用大尺度SST场来表示WWB规则，那么ENSO的预测技能可能会得到改进。一名研究生(在马克·凯恩的领导下)和一名博士后(在Eli Tziperman的领导下)将根据这笔赠款接受教育、指导和培训。

Westerly wind burst (WWB) events are known to play an important role in El Nino Southern Oscillation's (ENSO) dynamics. The events are usually viewed as stochastic forcing that is independent of and external to the large scale ENSO dynamics. There are indications, however, that the occurrence of these events, and their characteristics, are influenced by the large scale SST structure, and hence by ENSO. This study will explore the dynamical consequences of the possibility that the timing and other characteristics of WWB events are partially regulated and controlled by the large scale SST distribution. That is, the study will examine the extreme possibility that these events occur only when the large scale SST structure is at a certain configuration. For example, when the warm pool is extended eastward beyond the dateline. In this scenario the WWB events will be treated as an inherent part of the deterministic ENSO dynamics rather than as external stochastic forcing. The study will first analyze observations in order to try and establish the characteristics of such a possible regulation of the timing or characteristics of WWB events by the large scale SST field. Next, the implications of such regulated switching of WWB events by the large scale ENSO dynamics will be studied using a hierarchy of models. The model hierarchy will include a hybrid coupled model (ocean general circulation model coupled to a statistical atmosphere), an intermediate coupled model, and a conceptual delayed oscillator model. Broader impacts of the research include possible improvement of ENSO's prediction skill, should the proposed research find a way to include a representation of WWB regulation by the large scale SST field in current ENSO prediction models. A graduate student (under Mark Cane) and a post-doc (under Eli Tziperman) will be educated, mentored and trained under this grant.