Global surface layer salinity change detected by Argo and its implication for hydrological cycle intensification

We investigated changes in the global distribution of surface-layer salinity by comparing 2003–2007 Argo-float data with annual mean climatological surface-layer salinity data for 1960–1989 from the World Ocean Database 2005. The two datasets showed similar patterns, with low values in subpolar and tropical regions and higher values in the subtropics. The recent Argo data indicate that the contrast between low and high salinity has intensified in all areas except the subpolar North Atlantic. The intensified contrast of the surface layer salinity was maintaining for 2003–2007. Using a simple method, we attempted to estimate evaporation and precipitation changes on the basis of surface-layer salinity changes. The results show a high probability that the global hydrological cycle has increased in the past 30 years.