Vertical Distribution of Salinity

  • Salinity at the surface of the sea is decreased by the input of fresh waters or increased by the loss of water to ice or evaporation. Thus both the trends of increase and decrease of salinity with increasing depths have been observed
  • Salinity increases with increasing depth from 300 meters to 1000 meters in high latitudes i.e. there is positive relationship between the amount of salinity and depth because of denser water below but salinity becomes more or less constant beyond 1000 m depth
  • Salinity decreases between the depth zone of 300 meters to 1000 meters in the low latitudes but it becomes more or less constant beyond 1000 m depth
  • It appears from the above mentioned trends of vertical distribution of salinity that there is rapid rate of change of salinity (both increase and decrease) in the depth zone of 300m-1000m. This zone of steep gradient of salinity is called halocline
  • Maximum salinity is found in the upper layer of the oceanic water. Salinity decreases with increasing depth. Thus, the upper zone of maximum salinity and the lower zone of minimum salinity is separated by a transition zone which is called as halocline, on an average above which high salinity is found in the low latitudes while low salinity is found in the high latitudes

Vertical Distribution of Salinity