Investigating decadal changes in sea surface salinity in oceanic subtropical gyres

Abstract

AbstractSea surface salinity trends over the past six decades were analyzed, as salinity can be a potential diagnostic of the acceleration pattern of the global water cycle. Global salinity data from Simple Ocean Data Assimilation reanalysis highlight surface ocean salinity trends in evaporative‐dominated subtropical gyre systems over the period of 1950–2010. Global salinity observations from NASA's Aquarius and European Space Agency's Soil Moisture and Ocean Salinity missions were used with relation to more recent trends and future implications on global water cycle studies. Results indicated an average salinity increase of 0.12 practical salinity unit (psu) in the subtropical gyres over the 61 year study, with the greatest increase occurring in the southern hemisphere gyres. Lateral gyre drift was also inferred through salinity, as three of five gyres showed significant drift over 60 years within their respective basins. There is evidence of periodicity related to these migrations on multidecadal time scales. A comparison of satellite, in situ, and model simulations was conducted in an effort to resolve the near‐surface salinity stratification as it pertains specifically to the subtropical gyre regions and also to show the growing relevance of satellite data in global water cycle studies.