Interbasin Differences in Interannual Variations of the Antarctic Circumpolar Current Transport

Despite the critical role of the Antarctic Circumpolar Current (ACC) in global convey belt, its temporal variability and spatial difference are poorly investigated due to the lack of full-depth observations. This study quantitatively investigates the interannual variability of the ACC transport in different basins using Gravity Recovery and Climate Experiment (GRACE) ocean bottom pressure (OBP) data and In Situ Analysis System 17 (ISAS17) temperature and salinity fields. The results reveal that the interannual variation differs significantly in the Indian basin, the Pacific and Atlantic basins, and is likely caused by the meridional distribution of the wind stress curl, rather than the westerly winds. The interannual variation is correlated with the Southern Annular Mode (SAM) in the Indian basin, but also modulated by El Nino-Southern Oscillation (ENSO) in the Pacific and Atlantic basins. The results are further verified by a mass conservation ocean model with elaborating the important influence of both local and global atmospheric variability on the spatial-temporal variability of the ACC. The difference of the ACC transports in the major basins might be ascribed to the respective meridional transport in each basin.