Consider the following factors:

1. Rotation of the Earth

2. Air pressure and wind

3. Density of ocean water

4. Revolution of the Earth

Which of the above factors influence the ocean currents?

The correct answer is 1, 2 and 3.

Factors affecting Ocean Currents-

• Density-
  • Varying density caused by temperature and salinity in oceans led to vertical currents in oceans. 
• Air pressure and wind-
  • Monsoon winds are responsible for the seasonal reversal of ocean currents in the Indian Ocean.
  • Further influence of atmospheric pressure and insolation causes variation in winds movements which affects ocean currents eventually.
• Rotation of Earth-
  • The Coriolis effect is a result of the rotation of the earth. 
  • Coriolis force causes the mater to move right in the northern hemisphere and left in the southern hemisphere.
• Revolution of Earth
  • The Revolution of the earth does not influence the ocean currents.

Important Points

• The primary forces that influence the currents are:
  • heating by solar energy;
  • wind;
  • gravity;
  • Coriolis force.
• The secondary forces that influence the currents are:
  • Temperature difference;
  • Salinity difference