2015 Bernhard Haurwitz Memorial Lecture: Model Diagnosis of El Niño Teleconnections to the Global Atmosphere–Ocean System

Abstract

Abstract The El Niño–Southern Oscillation (ENSO) phenomenon is one of the most prominent modes of atmospheric and oceanic variability on interannual and interdecadal time scales. The essential ENSO signals originate from the tropical Pacific (TP). However, the impacts of ENSO are felt in many other parts of the world. Major ENSO events are accompanied by notable changes in the extratropical atmospheric circulation in both hemispheres, various monsoon systems located beyond the TP, global air temperature and precipitation patterns, and the sea surface temperature (SST) distribution throughout the World Ocean. During the past several decades, this author has participated in a sustained effort to study the processes contributing to these “teleconnections” between ENSO forcing in the TP and variations in the atmosphere–ocean system elsewhere. These investigations are based on a large suite of experiments with several generations of general circulation models (GCMs) at the Geophysical Fluid Dynamics Laboratory (GFDL). These experiments are specifically designed to reveal various facets of the teleconnections with ENSO. In this lecture, a summary is given of the principal findings of this series of model studies. An account is given of the train of thought underpinning the sequence of experiments described herein, so as to illustrate how certain experimental setups have been motivated by the problem or hypothesis at hand.