Trends in the salinity of the North Atlantic waters according to ocean reanalysis data in 1980–2011

Long-term trends in the North Atlantic Ocean (0°–70°N, 8°–80°W) salinity are estimated from several ocean reanalyses and objective analyses over the period 1980–2011. The obtained estimates are based on the application of a nonparametric method of regression analysis (quantile regression) to the monthly ocean salinity for a quantile value of 0.5. During the period under consideration, in the latitude band 0°–15° N in the 10–50 m layer, salinity decreased by 0.17 ± 0.10 PSU. In the latitude band 20°–35° N the increase in salinity in the 10–400 m layer is 0.08 ± 0.03 PSU. In the eastern part of the Subtropical Atlantic (30°–40° N, 25°–45° W), significant salinization of the upper 400 m layer occurs in all months. This means a northwestward expansion of the high salinity region in the subtropics. In the western part of the subpolar gyre, salinity in the upper 400 m layer increased by 0.20 ± 0.05 PSU over this 32-year period.