The Global Ocean Conveyor Belt
Oceanography is the study of the physical, chemical, and biological features of the ocean. Ocean currents are a critical component, acting as a global heat distribution system.
Surface Currents
Driver: Primarily driven by global wind patterns. The friction between the wind and the ocean surface drags the water along.
Influence: The direction of these currents is influenced by the Coriolis effect and the shape of the ocean basins.
Gyres: The Coriolis effect deflects the currents, causing them to form large, circular patterns called gyres. These gyres flow clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere.
Example: The Gulf Stream is a powerful warm surface current in the Atlantic Ocean that carries warm water from the tropics towards Northern Europe, significantly moderating its climate.
Deep Ocean Currents (Thermohaline Circulation)
Driver: Driven by differences in water density, which is determined by temperature (thermo) and salinity (haline).
Mechanism:
1.Near the poles, surface water becomes very cold and salty (as sea ice forms, it leaves the salt behind in the remaining water).
2.This cold, salty water is very dense and sinks to the deep ocean floor.
3.This sinking water pushes deep water along, creating a slow-moving global 'conveyor belt' that circulates water throughout all the world's oceans. A full cycle can take around 1,000 years.
Salinity
Salinity is the measure of the total amount of dissolved salts in water. The average ocean salinity is about 35 parts per thousand (ppt).
Factors that Increase Salinity: Evaporation (removes fresh water, leaves salt behind) and the formation of sea ice.
Factors that Decrease Salinity: Precipitation (rain/snow), runoff from rivers, and the melting of glaciers and sea ice.
Climate Regulation
Ocean currents play a vital role in regulating the Earth's climate by transporting vast amounts of heat from the equator towards the poles. Without this distribution system, the tropics would be much hotter and the polar regions much colder.