Linear trends in salinity for the World Ocean, 1955-1998

[ 1] Quality controlled oceanographic profile salinity measurements from the World Ocean Database 2001 ( WOD01) were used to calculate linear trends of zonally averaged salinity anomalies for running five year periods from 1955 - 1959 through 1994 - 1998 for the World Ocean and the Atlantic, Pacific, and Indian Ocean basins from the surface to 3000 meters depth. Each basin exhibits large-scale, coherent trends. Most of the Pacific is freshening with the exception of the subtropical South Pacific. The Atlantic exhibits a deep freshening in the subpolar gyre and a shallower, more intense increase in salinity in the tropics and subtropics. The Indian Ocean is becoming more saline at all latitudes in the upper 150 meter layer, with a subsurface freshening between 40 degrees S and the equator in the 250 - 1000 meter layer. There is freshening in both the Weddell and Ross Seas.