Improved Simulation of ENSO Variability Through Feedback From the Equatorial Atlantic in a Pacemaker Experiment

Abstract

The tropical Pacific Ocean interacts with the tropical Atlantic Ocean on interannual time scales. However, most coupled climate models misrepresent and/or underestimate these teleconnections, which have important implications on the periodicity of the El Niño-Southern Oscillation (ENSO). Imposing the observed sea surface temperature over the tropical Atlantic from 1970 onwards, a pacemaker experiment is constructed using the second version of the Australian Community Climate and Earth System Simulator Coupled Model (ACCESS-CM2). Compared with control runs which reasonably simulate the interaction between ENSO and the north tropical Atlantic variability, the pacemaker experiment significantly improves the impact of the Atlantic Niño/Niña on ENSO. This enhanced teleconnection contributes to a more realistic ENSO periodicity compared with the control runs, thus suggesting that capturing the influence from equatorial Atlantic variability is important for an improved ENSO simulation.