Account for variations in oceanic salinity and discuss its multi dimensional effects.
Salinity is the amount of saltiness present in water. In is expressed in parts per thousand. Average salinity is around 35. However, there is variation in salinity because of numerous factors such as
- The rate of evaporation,
- The amount of fresh water added and
- The degree of mixing of water by ocean currents.
In the water near the Trade wind deserts (between 20 and 30 N and S) salanity is high due to excess evaporation caused by high temperature and low humidity. In contrast, the temperate oceans have lower salinity due to less evaporation.
Fresh water is added into oceans by precipitation, streams and icebergs. Equatorial water has less salinity due to heavy rainfall (almost on a daily basis). Water near the mouth of huge rivers like Amazon, Ganga, Mekong, Congo and Irrawaddy has lower salinity due to dilution by fresh water.
Free mixing of water by surface and sub-surface currents result in constant salinity near average(35 parts per thousand). Partially or whole enclosed seas such as Caspian Sea, Red sea, Mediterranean Sea and the Persian Gulf have high salinity because of lack of proper mixing of water with the rest of oceans.
The variation in salinity has multidimensional effects on the ocean.
- The deep ocean currents are affected because of salinity. Water with higher salinity is denser and flows below the less dense low salinity water. These density differences can cause water to move and climate patterns to shift.
- Global weather patterns are also impacted by salinity patterns.
- The thermohaline circulation is the principal mechanism by which oceans store and transport heat. They have a overbearing impact on global climate.
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