There is no definite trend in the distribution of salinity along the depth. However.
some trends emerge from the distribution of salinity in the vertical plane:
1. In the polar region, salinity is low on the surface and it increases towards the depth. Salinity remains low on the surface due to the supply of clean melt water from glaciers.
2. In the mid latitudes, salinity increases till the depth of 400 meters. After this, the amount of salinity reduces along with the depth. It happens due to more evaporation and low availability of clean water on the surface.
3. In the equatorial region, salinity is low on the surface, it increases till the depth of one thousand meters, and after that, it again starts reducing.