Ocean Currents and Circulation

Ocean Currents

• Definition: The movement of ocean water in a specific direction, driven by several factors such as wind, tides, and the Coriolis force.
• Types:
  • Surface currents: driven by wind and occur in the top 400-500 meters of the ocean.
  • Deep-water currents: driven by density differences and occur below 400-500 meters.
• Characteristics:
  • Speed: varies from 0.05 to 5 km/h.
  • Depth: ranges from surface to abyssal zones.

Wind-driven Circulation

• Definition: The movement of ocean water driven by wind stress.
• Mechanisms:
  • Ekman transport: wind-driven water movement at the surface, resulting in a 90-degree deflection to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
  • Ekman spiral: a helical pattern of ocean currents, with the surface current deflected to the right/left, and the deep-water current deflected to the left/right.
• Effects:
  • Creates large-scale circulation patterns, such as gyres.
  • Influences ocean temperature, salinity, and nutrient distribution.

Upwelling

• Definition: The upward movement of deep, nutrient-rich water to the surface.
• Causes:
  • Wind-driven Ekman transport.
  • Coastal geometry and bathymetry.
• Effects:
  • Increases ocean productivity and supports marine life.
  • Affects coastal climate and weather patterns.
  • Impacts ocean chemistry and carbon sequestration.

Meridional Overturning

• Definition: The poleward flow of ocean water at the surface, with a return flow at depth.
• Characteristics:
  • Thermohaline circulation: driven by density differences between warm, salty water and cold, fresh water.
  • Meridional overturning circulation: a component of the thermohaline circulation, involving the exchange of water between the equator and the poles.
• Effects:
  • Regulates global climate by transporting heat and nutrients.
  • Influences ocean chemistry and carbon sequestration.

Thermohaline Circulation

• Definition: The deep-water circulation driven by differences in temperature and salinity.
• Mechanisms:
  • Formation of deep water: occurs at high latitudes, where water is cooled and sinks.
  • Deep-water flow: driven by density differences, with cold, fresh water sinking and warm, salty water rising.
• Effects:
  • Regulates global climate by transporting heat and nutrients.
  • Influences ocean chemistry and carbon sequestration.
  • Plays a critical role in the global ocean's carbon cycle and ocean acidification.

Ocean Currents

• Ocean currents are driven by wind, tides, and the Coriolis force.
• There are two types of ocean currents: surface currents (driven by wind, occurring in the top 400-500 meters) and deep-water currents (driven by density differences, occurring below 400-500 meters).

Wind-driven Circulation

• Wind-driven circulation is the movement of ocean water driven by wind stress.
• Ekman transport and Ekman spiral are two mechanisms of wind-driven circulation.
• Ekman transport causes a 90-degree deflection to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
• The Ekman spiral is a helical pattern of ocean currents, with the surface current deflected to the right/left, and the deep-water current deflected to the left/right.
• Wind-driven circulation creates large-scale circulation patterns, such as gyres, and influences ocean temperature, salinity, and nutrient distribution.

Upwelling

• Upwelling is the upward movement of deep, nutrient-rich water to the surface.
• Upwelling is caused by wind-driven Ekman transport and coastal geometry and bathymetry.
• Upwelling increases ocean productivity, supports marine life, affects coastal climate and weather patterns, and impacts ocean chemistry and carbon sequestration.

Meridional Overturning

• Meridional overturning is the poleward flow of ocean water at the surface, with a return flow at depth.
• Thermohaline circulation is driven by density differences between warm, salty water and cold, fresh water.
• Meridional overturning circulation regulates global climate by transporting heat and nutrients, and influences ocean chemistry and carbon sequestration.

Thermohaline Circulation

• Thermohaline circulation is the deep-water circulation driven by differences in temperature and salinity.
• Formation of deep water occurs at high latitudes, where water is cooled and sinks.
• Deep-water flow is driven by density differences, with cold, fresh water sinking and warm, salty water rising.
• Thermohaline circulation regulates global climate by transporting heat and nutrients, influences ocean chemistry and carbon sequestration, and plays a critical role in the global ocean's carbon cycle and ocean acidification.