Definition of Ocean Currents: Ocean currents refer to the large-scale movement of water from one location to another.
Measurement: They are often measured in meters per second or knots (1 knot = 1.85 km/h or 1.15 miles/h).
Causes: Wind, density changes in water, and tides are primary factors driving ocean currents.


Tidal Currents

  • Mechanism: Tides cause strong currents along beaches, bays, and estuaries. These are known as tidal currents.
  • Predictability: Tidal currents follow consistent patterns and can be predicted for future dates.

Wind-Driven Currents

  • Surface Currents: Winds drive currents at or near the ocean’s surface.
  • Coastal Upwelling: Winds near coastlines can cause local currents leading to phenomena such as coastal upwelling.

Thermohaline Circulation

Density Changes: Driven by temperature (thermo) and salinity (haline) fluctuations, this process creates deep and shallow ocean currents that move more slowly than tidal or surface currents.

Impact on Human Activities

  • Climate Influence: Ocean currents affect climate patterns, such as cool waters along the west coasts of continents at tropical and subtropical latitudes, leading to relatively modest temperatures with limited fluctuations.
  • Marine Climate: Warm waters along the west coasts at middle and higher latitudes create a marine climate with pleasant summers and generally warm winters.
  • Rainy Climates: Warm currents parallel to east coasts in tropical and subtropical latitudes result in warm and rainy climates.
  • Fishing Grounds: The mixing of warm and cold currents replenishes oxygen, promoting plankton growth, which supports fish populations. The best fishing grounds are found in these mixing zones.


  • AMOC Instability: Recent studies indicate that the Atlantic Meridional Overturning Circulation (AMOC) is losing its stability.
  • AMOC Role: AMOC, part of the ocean conveyor belt or Thermohaline Circulation (THC), distributes heat and nutrients across the world’s oceans.
  • Process: AMOC carries warm surface waters from the tropics towards the Northern Hemisphere, where they cool and sink, then return to the tropics and South Atlantic as a bottom current.
Legacy Editor Changed status to publish July 2, 2024