NTE Praxis: Oceanography Salinity


It is defined as the ratio between the weight of the dissolved material and the weight of sample sea water.

  • Generally salinity is defined as the total amount of solid material in gm. Contained in one kg. Of sea water and is expressed at part 1000 means 30 gm.

  • The average salinity of 35% is recorded between 10° 30° latitude in the southern hemisphere.

  • The zone between 40° 60° latitude in both the hemisphere records lowest salinity where it is 31%-33%

Pacific Ocean

  • Near the equator, salinity is 34.85%

  • It increases to 35% between 15° 20° latitude in the north hemisphere; But in the southern hemisphere, it increases to 36% i.e.. More than sea

  • Besides salt, silver, gold and radium also occur but in minute proportion in sea water.

  • These elements are 0.3 (silver), 0.006 (gold) and 0.0000002 mg/metric tonne or part/1000 million.

Atlantic Ocean

  • average salinity is 35.67%

  • highest is between 15° 20° latitude

  • in 5° North latitude, salinity is 34.98% and in 15° North, it is 36%

  • in 15° South, salinity is 37.77%.

Indian Ocean

  • from 0° 10° North latitude, salinity is 35%

  • 10° 30° North, the salinity is 33.5%

  • near Persian Gulf, 40%; highest is in Red sea, 3641% (In the landlocked sea, lowest salinity js in Caspian sea, i.e.. 14% in the northern part. But in the Kara Bnpa? bav salinity is highest i.e.. 170%).

  • near Salt Lake (US), salinity is 220%. In Red sea, salinity is 240%, in Dead sea, it is 238%.

Distribution of Salinity

The average salinity in the oceans and the sea is 35%.

Horizontal Distribution: On an average, salinity decreases from equator towards tne poles. The equator accounts only 35% of salinity.

  • The highest salinity is observed between 20° 40° N. Because this zone has high temperature, high evaporation, but low rainlall least i.e.. 31%, near Manchurian, it is 34%, this salinity in Manchuria is severe because of Oyashio current coming from Berring Strait.

  • in the Southern hemisphere, lowest is near the Peruvian and Chilean coast i.e.. 33%.