Ocean Circulation
What Causes Ocean Circulation?
- Ocean circulation systems are driven by differences in temperature and salinity
- The resulting difference in water density drives the ocean conveyor belt, which distributes heat around the world and thus affects climate
Ocean Conveyor Belt
- Ocean currents redistribute heat energy around the globe
- The currents (warm or cold) act a bit like 'rivers' of water in the sea
- Cold currents move towards the equator and warm currents towards the poles
- Each ocean has its own pattern of currents
- E.g. the warm Atlantic Ocean waters of the low latitudes are moved to high latitudes via the North Atlantic Drift
- All ocean currents are triggered by the prevailing surface winds created by global atmospheric circulation
- Ocean circulation is also maintained through convection currents driven by cold water freezing into ice at the poles
- The polar cold waters contain denser, saltier sea water, which sinks to the ocean floor
- Water then flows in above it at the surface, which forms a current
- The deep ocean currents then flow towards Antarctica along the western Atlantic basin, before splitting off into the Indian and Pacific Oceans where the water begins to warm up
- The warming makes the water less dense so it loops back up to the ocean surface in the South and North Atlantic Ocean
- The warmed surface waters continue to flow around the globe and eventually return to the North Atlantic, where the cycle begins again
- This movement of water is known as the thermohaline circulation and drives the ocean conveyor belt
The ocean conveyor belt transports heat and energy around the world, affecting climate
