Understanding the Critical Role of Seasonality for El Niño/Southern Oscillation (ENSO) Variability, Using Empirical Stochastic-Dynamic Models and Physics-Based Coupled Models

厄尔尼诺/南方涛动是从季节到年度时间尺度上气候波动的最大来源。它在世界各地产生了巨大的社会影响。大多数厄尔尼诺现象倾向于以类似的方式在整个季节中演变：从5月或6月左右开始，在日历年末达到峰值，并在接下来的(北部)春季消失。尽管有这些相似之处，但个别厄尔尼诺事件的演变方式略有不同--但很重要--导致了不同程度的影响。人们还不清楚季节性因素在控制厄尔尼诺现象演变过程中的作用。该项目通过开发和利用一套免费工具来研究不同类型厄尔尼诺事件的季节性演变。这项研究包括开发经验模型以确保分析以观测为基础，使用以物理为基础的模型模拟，以便对具体的物理过程进行系统测试，以及应用新的分析工具，将动力系统的理论想法与对厄尔尼诺季节演变的具体特征的应用分析联系起来。这项研究将促进对不同季节变化过程为什么以及如何导致个别厄尔尼诺事件的季节性演变的理解。这项研究的影响有三个方面。首先，这项研究将促进我们对厄尔尼诺事件如何发展的理解，从而为理解和预测厄尔尼诺现象的广泛社会影响提供信息。其次，这项研究将继续开发强大的新经验模型，这些模型可以用于理解和预测地球系统中其他与社会相关的现象。最后，该项目将有助于培训下一代气候科学家，有机会与联邦实验室的科学家合作，这些科学家正在开发经验模型开发的基本理论，并将这些模型应用于实际物理问题。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The El Niño/Southern Oscillation is the largest source of climate fluctuation on seasonal to year-to-year time scales. It has immense societal impacts around the world. Most El Niño events tend to evolve throughout the seasons in similar ways: beginning around May or June, reaching their peak amplitude toward the end of the calendar year, and dying off through the following (northern) spring. Despite these similarities, individual El Niño events evolve in slightly different – but important – ways, leading to different levels of impacts. The role of seasonality in controlling how El Niño evolves is not yet well understood. This project examines the seasonal evolution of different types of El Niño events by developing and utilizing a suite of complimentary tools. The study includes the development of empirical models to ensure that analysis is grounded in observations, the usage of physics-based model simulations that allow systematic testing of specific physical processes, and the application of new analytical tools that link theoretical ideas of dynamical systems to applied analysis of specific features of El Niño’s seasonal evolution. The study will advance understanding of why and how different seasonally varying processes lead to the seasonal evolution of individual El Niño events.The impact of this study is threefold. First, the study will advance our understanding of how El Niño events develop to inform efforts to understand and predict El Niño’s wide ranging societal impacts. Second, the study will continue the development of powerful new empirical models that can be applied to understand and predict other societally relevant phenomena in the Earth system. Lastly, the project will contribute to training the next generation of climate scientists, with opportunities to work with scientists in federal laboratories who are developing the underlying theories of empirical model development as well as application of those models to real physical problems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.