Further Studies of El Niño-Southern Oscillation (ENSO) Dynamics

University Of Hawaii, Honolulu

Investigators

Abstract

The El Nino - Southern Oscillation (ENSO) phenomenon is responsible for nearly global variations in climate. ENSO has major effects on human health, safety, and food production throughout the tropics and the Americas. It exhibits a rich spectrum of variations on many different timescales. Under this award the PI will address fundamental questions about the dynamics of ENSO: How does the stability of ENSO vary among different models; how will it change as climate changes? What are the sources of the different periodicities of ENSO? Do interactions between ENSO and variability on much shorter timescales influence the stability of ENSO? These questions will be addressed using an atmosphere-ocean stability index developed by the PI under his previous award. The index will be applied to various coupled atmosphere-ocean climate models, which exhibit different ENSO behavior, and to assess the stability of ENSO under different climate conditions. Scale-interactions between slow ENSO modes and fast variability will be investigated and the impact of these scale interactions on the stability of the coupled ENSO modes will be determined. The PI will explore the physical mechanisms leading to the possible co-existence of multiple independent coupled modes that resemble ENSO and will determine their relevance to its observed behavior. A hierarchy of coupled models will be used. The study will lead to a better understanding of the dynamics and predictability of ENSO. Broader impacts of this research are its potential contributions to improved predictions of ENSO and to assessments of how ENSO will change as the global climate changes.