Marine Currents – Concept, types and causes

We explain what marine currents are and the types that exist. In addition, the causes of its formation and the main marine currents.

What are ocean currents?

It is called Ocean currents or ocean currents to a type of characteristic movement of the waters that constitute the oceans and the most extensive seas, and that are due to a multitude of factors, both to the earth’s rotation, to the winds and the location of the continents.

Sea currents often involve both cold and warm bodies of water, which connect various climatic bands of the globe, traveling both superficially and underwater:

• The warm currents. They are surface waters that originate in the oceans of the intertropical zone and that migrate from the eastern coasts of the continents towards the middle and high latitudes, against the Earth’s rotation and only in the northern hemisphere.
• The cold currents. They are waters of low temperature and great depth, which start from the intertropical or subtropical zone, and compensate the effect of the warm ones when they reach the western coasts of the continents. They are particular to the Arctic regions, since in the Antarctic area there is hardly a circular current around the pole.

The constant displacement of these ocean currents throughout the world allows to maintain an energy and caloric cycle on the planet, which results in a set of more or less fixed climates in certain regions, such as dry climates on the western coasts of the intertropical or subtropical zone, and warmer and more humid climates on the western coasts of the continents in mid-latitudes and high. The same occurs with salinity levels in ocean waters. This joint cycle is known as Circulation thermohaline world.

Types of ocean currents

We can talk about the following types of currents, according to their characteristics:

• Ocean currents. They present a constant movement generated by the Earth’s rotation, generally in an east-west direction in the intertropical zone, or in the opposite direction in the middle or high latitudes.
• Tidal currents. Periodic currents of daily cycle, which produce the attraction of the Moon and the Sun on the surface of the waters, that is, in warm waters. They displace huge amounts of water from the northern hemisphere to the south and vice versa.
• Wave currents. Produced by winds, especially storms or hurricanes, they occur on the surface of the waters and have a limited impact.
• Coastal drift currents. They are due to the meeting of the currents with the outline of the relief of the coasts, which forces them to modify their orientation or direction.
• Density currents. Those that originate in the contact zone between two bodies of water with different densities, such as those more and less saline, or more and less warm. They usually occur in straits between different seas and oceans, along the equatorial axis, or along the Arctic Circle.

Causes of ocean currents

The three most important physical causes of ocean currents are:

• Earth movements. Both the translation and the rotation of the planet cause constant movements of the water masses, although in many cases they move in the opposite direction to the Earth’s rotation.
• The planetary winds. It is not true that winds directly cause tides, but they do contribute to it, by displacing not only surface waters (as in waves), but also by mobilizing the atmosphere to circulate heat energy from the environment, which has an impact on the water.
• The emergence of cold waters. Deep ocean waters are cold because they are denser and have less energy. These waters rise to the surface in specific areas of the intertropical zone, pushing the warm waters in their path.

Major ocean currents in the world

The main known marine currents are, according to the Ocean:

• Arctic Ocean.
  • West Greenland Current.
  • East Greenland Current.
  • Norway stream.
• Atlantic Ocean.
  • West Indies Stream.
  • North Atlantic current.
  • South Atlantic current.
  • Benguela current.
  • Current of Brazil.
  • Cape Horn Current.
  • Canary current.
  • Caribbean current.
  • North Equatorial Current.
  • South Equatorial Current.
  • Gulf Stream.
  • Guinea current.
  • Labrador Stream.
  • Madagascar current.
  • Malvinas current.
  • Current of the north of Brazil.
  • Portugal current.
  • Spitzbergen current.
• Pacific Ocean.
  • Alaska Stream.
  • Aleutian Stream.
  • Eastern Australian Current.
  • California Stream.
  • Cromwell current.
  • Humboldt current.
  • Kamchatka Stream.
  • Kuroshio or Japan current.
  • Mindanao Stream.
  • Child stream.
  • Oyashio current.
  • North Pacific Current.
• Indian Ocean.
  • Current of the Needles.
  • Western Australian Stream.
  • South Equatorial Current.
  • Eastern stream of Madagascar.
  • Leeuwin current.
  • Madagascar current.
  • Monsoon Stream.
  • Mozambique current.
  • Somalia Stream.
• Antartic Ocean.
  • Antarctic current.
  • Antarctic Circumpolar Current.
  • Spin Wedell.