Opposing changes in subpolar ocean heat content due to meridional heat advection driven by the Southern Ocean wind anomaly

Abstract. The global ocean has been warming significantly due to rapid climate change, leading to conspicuous changes in the subpolar Southern Ocean. Our study reveals that the heat exchange between Antarctic and subtropical oceans driven by wind, which plays an important role in modulating changes in regional ocean heat content (OHC) through meridional heat advections. In this study, we used the observed objective analysis and reanalysis datasets to explore the changes in subpolar ocean heat content and analyze attributions to the remarkable regional discrepancy. We found a notable difference in OHC trends between the Atlantic–Indian sector and the Pacific sector, which could be attributed to the inverse meridional heat advection caused by wind anomalies. Atlantic–Indian sector warming was significantly modulated by increasing meridional heat advection induced by the poleward westerly wind. In the Pacific sector, the enhanced wind resulted in substantial cold-water advection equatorward, causing significant cooling. These opposite advections are also occurring with the corresponding regional front movement, which also indicates the meridional heat exchange between oceans. This study highlights that wind anomalies play an important role in modulating the heat exchange between Antarctic and subtropical oceans. Consequently, the atmospheric forcing may become more significant to the heat redistribution in the Southern Ocean in the warmer future.