Impact of ENSO and IOD Events On Upper Ocean Heat and Salt Transport in Coupled Models over the Tropical Indian Ocean

Abstract

The present study investigates the performance of the 6th phase of coupled models in representing upper ocean heat and salt transport at different straits of the Tropical Indian Ocean (TIO) during El Niño-Southern Oscillation (ENSO) (El Niño and La Niña) and Indian Ocean Dipole (IOD) phases (positive and negative). To explore the mean features of the transport, the present study utilises CMIP6 models and Ocean Reanalysis System 5 (ORAS5) observations for the period from 1965 to 2014. The heat and salt transport analysis at different straits in the TIO suggested northward and southward transport and show significant seasonal variability. Northward transport occurred during the post-monsoon season, while southward transport occurred during other seasons. Coupled models show significant variations in the upper ocean (50 m), which are consistent with the observations. Results also reveal that during ENSO periods, variations occur during both the positive and negative phases. These findings suggest that strait-based transports of both heat and salt in coupled models in the TIO are sensitive to the phases of ENSO and IOD.