What Are Surface Currents Driven By?

Surface ocean currents span the globe in a complex pattern.

Though unseen by the casual observer, surface currents are powerful ocean forces that play vital roles in everything from the health of marine ecosystems to ocean temperatures to climate changes.

Definition

Ocean currents are continuous flows of ocean water that follow a definitive course. Surface currents are currents that occur in the top 400 meters, or about 1,300 feet, of the ocean's surface.

Features

Surface currents flow in large circular patterns called gyres. Individual currents can be narrow or broad, fast or slow, deep or shallow.

Wind

Surface currents are mainly driven by recurrent global wind patterns that move the water in specific directions.

Coriolis Effect

Because of the Earth's rotation, winds--and consequently surface currents--are deflected to the right or left instead of moving straight up and down, causing clockwise gyres in Northern Hemisphere oceans and counterclockwise gyres in Southern Hemisphere oceans. This phenomenon is known as the Coriolis effect.

Benefits

Surface currents bring warm water to cooler places, regulating ocean temperatures and regional climates. They also bring colder, nutrient-rich water into warmer places, which feeds ocean plants and animals.

References

• University Corporation for Atmospheric Research (UCAR): Surface Ocean Currents
• NASA SeaWifs Project and Smithsonian Ocean Planet: Ocean Currents
• NOAA's National Ocean Education: Currents