The temperature-salinity diagram, introduced by Helland-Hansen has become very important in Physical Oceanography for the study of water masses of the Oceans. But the seasonal and local variations of these parameters restrict the use of the T-S diagrams for the topmost layers of the Sea. Thus it has become necessary to describe the characteristics of the upper layers of the sea both in time and space. Though the seasonal variation below 20 m is not very prominent, localities influenced by processes like upwelling, local variations are very important. It is so because the surface layer will be completely replaced by the subsurface water. In such instances it is desirable to use a consistent nomenclature for the water masses identified to avoid confusion

water masses, temperature, salinity, depth, season, South eastern Arabian Sea