Salinity is directly positively related to seawater density.On an average, seawater density increases with increasing salinity and vice versa.E.g. Density of pure water is 1.00 g/cm3 and density of water with 35% salinity is 1.028 g/cm3.
The amount of insolation received varies from latitude to latitude. The Regions within the equator and 40° N and S latitudes are energy surplus regions because they receive abundant sunlight and hence more heat will be gained than lost.The Regions beyond 40° N and S latitudes are energy deficit regions because they lose more heat than that gained from sunlight.