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10. The Equatorial Counter Currents

Expedition Menu

1. Introduction
2. Tracking Drifters
3. Drifters Pacific
4. Drifters Atlantic
5. Drifters Indian
6. Velocity Pacific
7. Velocity Atlantic
8. Velocity Indian
9. Global Circulation
10. Counter Currents
11. Boundary Currents
Notice the counter currents along the equator, in orange, which flow in the opposite direction of each gyre. CURRENTS_small.gif (49032 bytes)
Image from Matthias Tomczak and copyright-protected

  • The counter currents exist along the equator where winds are quite weak, thereby allowing water pushed westward by the north and south equatorial currents to flow back eastward across the ocean basin.

  • Think of it this way.....the northern and southern equatorial currents, pushed westward by the trade winds, pile up water in the western portion of each ocean basin. For example, the sea surface is about 0.5 meter (20 inches) higher in the western Pacific near Indonesia than it is in the eastern Pacific near South America. At some point, gravity will cause this pile of warm water to flow back across the ocean basin where the winds are weak, which is along the equator.  This current is especially strong during years of the El Nino climatic event. 

  • The currents on the western and eastern sides of the gyres are called boundary currents, because they flow along the boundary between the ocean and the continents.

 
Last Updated on
July 1, 2011
Send to Don Reed
Department of Geology
San José State University

What direction do the counter currents along the equator flow in relation to the gyres?

a) With the flow of the gyres
b) Opposite the flow of the gyres near the equator
c) Both a and b