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

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

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.