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How well do climate models simulate ENSO? How well do we know ENSO?

Presentation Date
Thursday, December 16, 2021 at 7:50am
Location
Convention Center - New Orleans Theater C
Authors

Author

Abstract

The El Niño-Southern Oscillation (ENSO) is the dominant mode of variability at interannual timescales; decadal modulation of its characteristics is both a major source and consequence of tropical Pacific decadal variability. ENSO influences the global atmospheric circulation, causing droughts and floods, modulating the tropical cyclone activity, and altering marine and terrestrial ecosystems. While it has become clearer that ENSO-driven precipitation variations will intensify with the future increase of greenhouse gases in the atmosphere, model biases still contribute to uncertainties regarding the amplitude of these changes, and in possible changes to the dynamics of ENSO. It is therefore important to evaluate ENSO in state-of-the-art climate models and in observational datasets, in order to improve them. The International CLIVAR Pacific Region Panel has led the development of a community-wide synthesis to evaluate how well climate models simulate ENSO. We have applied this package to historical simulations from CMIP6, and to a variety of observational datasets. The results underscore the continuing need to improve climate models, in particular the representation of the background cold tongue SST and the seasonality of ENSO. They also highlight a wide diversity of ENSO representations in different observational datasets, especially for ENSO feedbacks but also in terms of mean precipitation. This work demonstrates the importance of choosing the right observational datasets for the right applications when evaluating and developing climate models. Our ongoing work aims to develop a consensus on which reference datasets to use for each metric, and how to best characterize uncertainties arising from observational limitations and sampling variability.

Funding Program Area(s)