I don't usually pay much attention to remote sensing, but this paragraph impresses me as highly significant: "The most important factor governing the dynamics of any fluid is the equation of state that relates its composition to its density. That ultimately determines the pressure gradients and hence the velocity and circulation. In the atmosphere, the important constituents are temperature and water vapour, while in the ocean it is temperature and salinity. Making seawater warmer or making it fresher (by adding rain or river water) both decrease the density and make the water more buoyant. Similarly, cooling and evaporation both make seawater more dense."