New findings on the route of heat transport between the Indo-Pacific and Southern Ocean
Since the end of the twentieth century, the global mean surface temperature (GMST) exhibited a shift from a rapid warming to an unexpected deceleration. An anomalous heat was transported from the Pacific Ocean into the Indian Ocean through a strengthened Indonesian Throughflow during the same period. Within this background, it is essential to continue tracking the fate of the anomalous heat arriving in the Indian Ocean to form a comprehensive picture of the global ocean energy redistribution. The anomalous heat may continue flowing westward into the Atlantic Ocean along the main pathway of the regional ocean currents via the South Equatorial Current (SEC) and Agulhas Current. However, here we examine an alternate pathway: a southward heat transport in conjunction with a weakened SEC, diverting the canonical westward transport. This additional transport pathway causes an increase in heat content in the South Indian Ocean mid-latitudes (15–30°S, 95–110°E), may contribute to the Southern Ocean warming, and intensifies hemispheric asymmetry of oceanic heat content. The heat increase has important climate impacts such as changes to rainfall and increased coral bleaching over the western coast of Australia. The new path discovered here may be an essential route of heat transport linking the tropical Indo-Pacific Ocean and the Southern Ocean in 2003–2012.
Authors would like to thank Dr. Stephen G. Yeager and Dr. Who Kim from NCAR for the help in the CESM model running. The research was partially supported by SOA Global Change and Air-Sea Interaction Project (GASI-IPOVAI-01-04, GASI-02-PAC-YGST2-02) and National Natural Science Foundation of China (41630963 and 41476007). We would also like to thank the Delaware Space and Sea Grant (NNX15AI19H and Na14OAR4170087) for financial support.
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