Air‐Sea Interaction in the Western Tropical Pacific and its Impact on Asymmetry of the Ningaloo Niño/Niña

Abstract

AbstractNingaloo Niño/Niña is the dominant interannual sea surface temperature (SST) variability off Western Australia with the former typically stronger than the latter. Although a recent study suggested that oceanic teleconnections from the Pacific partly contribute to the amplitude asymmetry, this seems counterintuitive as La Niña, which often induces the Ningaloo Niño, is generally weaker than El Niño. Here, mechanisms of the amplitude asymmetry in the oceanic teleconnection are investigated by analyzing reanalysis data and conducting ocean model simulations. Sensitivity experiments using a linear continuously stratified model reveal that stronger easterly wind anomalies in the western equatorial Pacific contribute to the stronger oceanic teleconnection during the Ningaloo Niño. Furthermore, a mixed layer heat budget analysis with a regional ocean model shows that negatively skewed SST anomalies in the central equatorial Pacific related to the skewed wind anomalies in the western equatorial Pacific, are mainly induced by vertical advection/diffusion and entrainment.