SMOS mission could offer early indicator of El Niño

Sea-surface salinity, the concentration of dissolved salts in the upper layer of the ocean, is much more than a measure of how salty the sea is. It responds rapidly to changes in rainfall, evaporation, river discharge and, specifically in polar regions, the melting and formation of sea ice. Salinity is both an important driver of ocean circulation and a tracer of the movement of water masses and surface currents.