Horizontal Distribution of Salinity

Salinity distribution in Surface waters


  • On an average, salinity decreases from equator towards the poles. However, it is important to note that the highest salinity is seldom recorded near the equator though this zone records high temperature and evaporation but high rainfall reduces the relative proportion of salt. Thus, the equator accounts for only 35‰ salinity
  • The highest salinity is observed between 20° N and 40° N (36‰) because this zone is characterized by high temperature, high evaporation but relatively low rainfall
  • The average salinity of 35‰ is recorded between 100 -300 latitudes in the southern hemisphere
  • The zone between 40 deg -60 deg latitudes in both the hemispheres records low salinity where it is 31‰ and 33‰ in the northern and the southern hemispheres respectively.
  • Salinity further decreases in the polar zones because of influx of Glacial melt-water. On an average, the northern and the southern hemispheres record average salinity of 35‰ and 34‰ respec­tively