Ocean Circulation Currents and Causes

What is a Current? Ocean water that moves in ‘streams’ or ‘rivers’ based on similar characteristics Two main types Surface Deep-water

Surface Currents Caused by winds Trade winds (N/S of Equator) Westerlies (mid latitudes)

Surface Currents These currents move horizontally in the upper part of the ocean’s surface. Develops from friction between ocean surface and wind blowing across it.

Surface Currents Upwelling When warm water is ‘blown’ away and cold nutrient rich water rises to the surface La Nina conditions - normal El Nino is when the upwelling becomes downwelling

Surface Currents Gyres Huge circular moving current systems that dominate the surfaces of the oceans.

Gyre:

Surface Currents Coriolis Effect is the deflection away from their original course as a result of Earth’s rotation.

Deep-Water Currents Density Current Moves vertically Results from density differences among the water masses

Deep-Water Currents Density Current Can be caused by a decrease in temperature or an increase in salinity

Deep-Water Currents Density Current Cold water from the poles sinks Can take thousands of years to make a complete cycle around the ocean floor

Conveyor Belt Model

Key Currents to Know Gulf Stream Warm Off east coast of US California Current Cold Off west coast of US