Impact of Ningaloo Niño on Tropical Pacific and an Interbasin Coupling Mechanism

Abstract

The Ningaloo Niño refers to the evident interannual variability of sea surface temperature anomalies in the southeast Indian Ocean (SEIO), which can be caused by the Pacific La Niña. Through performing atmospheric general circulation model experiments, this study shows that the Ningaloo Niño can also actively impact on the tropical Pacific. The sea surface temperature anomalies associated with the Ningaloo Niño induces negative sea level pressure anomalies extending from the SEIO to the Maritime Continent, strengthens western Pacific trade winds, and thus cools the central tropical Pacific. In turn, the central Pacific cooling anomalies generate cyclonic wind anomalies over the SEIO, and the strengthened trades enhance the Indonesian throughflow, with both enhancing the Ningaloo Niño. As such, a positive feedback loop associated with an interbasin coupling mechanism is proposed, which acts to amplify the Ningaloo Niño and its subsequent impact on the tropical Pacific.