CAREER: Narrowing the Spread: Process Understanding for Reduced Uncertainty in Future El Nino/Southern Oscillation Projections

University Of California-Santa Barbara, Santa Barbara CA

Investigators

Abstract

The El Nino/Southern Oscillation (ENSO) dominates worldwide climate variability, yet its overall sensitivity to climate change remains unknown. Climate models project distinctly different changes to future ENSO-driven oceanic variability, which are related in part to differences in simulated tropical Pacific mean climate changes. This project will improve understanding of ENSO response to climate change. The project will synthesize observational data with existing model ensembles and novel, targeted sensitivity experiments to provide both physical understanding of the ENSO climate change response and improved observational constraints on future ENSO projections. The project will train undergraduate and PhD students and postdoctoral researchers. Research results will be incorporated into a series of instructional modules on climate and ocean modeling (the “Climate DataLab”). Introductory modules will familiarize environmental science professionals with climate model fundamentals, and more advanced modules will describe ocean model parameterizations and dynamics. The project will also train undergraduate student researchers, providing data science skills and facilitating retention in STEM careers. The objective of this work is to improve constraints on future ENSO projections. The project will address how forced changes in ENSO are related to mean climate and mesoscale and submesoscale ocean dynamics. It will also examine how the mesoscale influences the interactions between ENSO and the mean state. The primary tool to be used will be an unprecedented array of CMIP-class ensembles. The project will also investigate whether the relationships between ENSO and mean and mesoscale dynamics are consistent across CMIP-class models. A suite of idealized ocean-only experiments and novel diagnostics for Tropical Instability Wave (TIW) activity will allow isolation of the influences of individual processes on mesoscale eddy behavior, and their interactions with mean climate. Additionally, the first set of fully coupled perturbed physics ensembles optimized for elucidating ocean physical controls on ENSO projections will be created and contrasted with the behavior of existing coupled model ensembles. When combined with the proposed development of new, more detailed emergent constraint diagnostics, the result will be more robust insights into how climate change may affect 21st century ENSO. 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.