Landmass

The water masses a term being used in oceanographic literature has been borrowed from meteorology. The water masses of specific characteristics are formed in different regions of the oceans by the processes occurring at the surface of the oceans, and ocean-atmosphere interactions at specific locations and sink from the surface to subsurface depths. They move from the region of formation and spread out to different oceans, and deep mixing eventually pulls them up through the thermocline over large areas of the ocean. It is this upward mixing that drives the deep circulation. The water mass distribution is controlled by density gradients. The two key parameters governing these differences are temperature and salinity and are routinely used to characterize it. The salinity maximum and minimum are used in a temperature – salinity (T – S) graph to distinguish a water mass in a certain area of the ocean. This method of water mass identification was introduced first time by Helland and Hansen (1916). A salinity maximum or minimum is defined as that point on a T-S curve 2 which has a salinity greater than or less than the value obtained by the mixing of the water above and below it on the curve (Stewart, 2003).