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Which currents appear to
have the most effect on the coasts of North
America?Think Critically0
0 2000 kilometers2000 miles60 °S30 °S0 °30 °N
60 °N60 °S30 °S0 °30 °N60 °N(^) West Wind Drift^
South Indian
Equatorial
Current
South Atlantic
Equatorial Current
North
Pacific Drift
North Pacific
Equatorial Current
North Atlantic
Equatorial
Current
North
Pacific
Equatorial
Current
North
Pacific
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Gulf Stream
North
Carolina
0
0
1 cm
190 km (118 mi)
Courtesy NASA
Adapted from Figure 12.5A on p. 347 in Murck, B.W.,
B.J. Skinner, and D. Mackenzie. Visualizing Geology,
Hoboken NJ: John Wiley and Sons, Inc. (2008).
a. Surface–Ocean Currents. Winds
largely cause the basic pattern of ocean
currents. The main ocean current flow—
clockwise in the Northern Hemisphere
and counterclockwise in the Southern
Hemisphere—results partly from the
Coriolis effect.
b. The Ocean Conveyor Belt. This loop consists of deep-ocean
currents that flow in the opposite direction from surface
currents, transferring heat and salt. Vertical motions associated
with the meridional overturning circulation drive the conveyor:
Cold, salty water near Antarctica and the Arctic Ocean sinks and
eventually flows northward into the Pacific Ocean, where it wells
up, eventually becoming warmer and fresher. Cold, salty, deep
water in the Atlantic Ocean comes from the Arctic Ocean. The
ocean conveyor belt affects regional and global climate.
c. The Gulf Stream. The Gulf Stream is a well-known
regional link in the ocean conveyor belt. In this satellite
image, the colors represent the water’s surface
temperature: red = warmest, and blue = coolest. The Gulf
Stream flows northeast along the North Carolina coast
and then out to sea, toward Europe.
The Global Ocean 275