Eddy‐Induced Meridional Salt Flux and Its Impacts on the Sea Surface Salinity Maxima in the Southern Subtropical Oceans. Issue 20 (22nd October 2019)

• Record Type: Journal Article
• Authors: Qu, Tangdong; Lian, Zhan; Nie, Xunwei; Wei, Zexun
• Is Part Of: Geophysical research letters. Volume 46:Issue 20(2019)
• Page Start: 11292
• Page End: 11300
• Publication Date: 2019-10-22
• Subjects: sea surface salinity -- eddies -- southern subtropical oceans; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2019GL084807
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Energetic eddy activities are observed in the southern subtropical oceans. Among the three ocean basins, eddies are most active in the subtropical south Indian Ocean, where they induce a northward salt flux in the north and a southward salt flux in the south, resulting in a divergence of salt in the central part of the basin. Further analysis of satellite‐sea surface salinity observations shows that eddy‐induced meridional salt flux takes more than half of the salt gain from the excess of evaporation over precipitation out of the sea surface salinity maximum region in the south Indian Ocean, while this ratio falls below 19% in the South Pacific and 12% in the South Atlantic. The result may partially explain why salinity of the sea surface salinity maximum in the south Indian Ocean is the lowest among the three southern subtropical oceans. Plain Language Summary: Sea surface salinity maxima are present in all the three southern subtropical oceans, as a result of large excess of evaporation over precipitation. Among the three southern subtropical oceans, salinity of the sea surface salinity maximum in the south Indian Ocean is the lowest. Surface freshwater flux is not the cause. Here we provide the first observation‐based estimate of eddy‐induced salt flux and its contribution to the sea surface salinity maxima in the three southern subtropical oceans. Our results suggest that enhanced eddy activities play a more important role in governing the sea surface salinity maximum in the south Indian Ocean than those in the South Pacific and South Atlantic. Key Points: Energetic eddy activities are observed in the southern subtropical oceans Eddy‐induced meridional salt flux counterbalances a significant portion of surface freshwater flux in the southern subtropical oceans Enhanced eddy activities play a particularly important role in governing the sea surface salinity maximum in the south Indian Ocean