Factors affecting Oceanic currents : Oceanography

 Factors affecting Oceanic Currents

  • Factors related to Earth’s rotation and Insolation

    • Equatorial and Counter currents : As the earth rotates from west to east, there is net movement of water from east to west. This water creates a gradient which further initiates counter currents in equatorial regions.
    • Heating by solar energy causes the water to expand. That is why, near the equator the ocean water is about 8 cm higher in level than in the middle latitudes.

    • Coriolis effect : As every freely moving body on earth surface is influenced by Coriolis effect, the moving waters are deflected by Coriolis force, which is by product of earth's rotation.

  • Factors related to winds and atmospheric circulation.

    • Drift currents : Wind blowing on the surface of the ocean pushes the water to move. Friction between the wind and the water surface affects the movement of the water body in its course.
      • Eg : North Atlantic Drift Current is Gulf stream waters moving under the influence of Westerly winds.
    • Seasonal reversal of winds in Indian ocean associated with Monsoon resulted in formation of seasonal currents in the Ocean
      •  E.g. Northern Indian Ocean (currents largely controlled by wind direction)

  • Factors related to Ocean

    • Differences in oceanic temperature, salinity and thus the density will result in flow of water within the oceans. High density water will sink and flow as subsurface current while less denser water flows along the surface to compensate for the sinking.
      • Eg : Labrador current, East Green land current etc

    • Oceanic bottom reliefs result in modification and sudden changes in oceanic current directions. E.g.-The north Atlantic Drift deflected upon striking the Wyville Thompson ridge.

  • Factors related to continents

    • The shapes and physiography of the coastal regions modifies and affects the pattern of oceanic currents.
      • Eg: Brazilian current modified by shape of the coast as the equatorial current reaches the Latin American coast


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