Transcript Ocean Currents

Currents
 Giant streams of
water that flow in
the ocean
 2 major types
 Surface: caused
by wind
 Deep: caused by
density/gravity
Surface Currents
 Created and maintained by wind
 Generally move from east to west near the equator
 Move west to east nearer to the poles
 This results in
giant circular
patterns called
gyres
 Gyres rotate
clockwise in the
northern
hemisphere and
counterclockwise
in the southern
hemisphere
Surface Currents
 The Gulf Stream
 Carries water out of the Gulf of Mexico north along the shore of N.
America and then east across the far N. Atlantic
 The Kuroshio Current
 Carries water out of the
South China Sea north along
the shore of Asia and then
east across the far N. Pacific
Surface Currents
 North Pacific Drift
 Very slow current that carries water across the northern
part of the Pacific Ocean, from west to east.
 West Wind Drift
 Very slow current that carries water around the world in
the far southern hemisphere, from west to east
Surface Currents
 North Pacific Gyre
 General clockwise rotation of
the Pacific Ocean, north of the
equator. Near the center is
relatively calm, current free
water

There is NOT a giant garbage
island in the middle of this Gyre,
BUT there is a lot of microscopic
plastic pollutants in the water.
Surface Currents
 North Atlantic Gyre
 General clockwise rotation
of the Atlantic Ocean, north
of the equator. Near the
center is calm current free
water called the Sargasso
Sea

The Sargasso Sea is NOT a
solid mass of seaweed that
mysteriously clears ships of
their crews.
Deep Currents
 Very slow moving currents that are caused by
differences in density
 The deepest is the Antarctic Bottom Water
 Very cold water = very
dense water
 Freezing water off the
surface leaves very saline
water behind = very dense
water
 This super-dense water
sinks to fill the deepest
parts of the ocean
 This current is very slow
Deep Currents
 North Atlantic Deep Water
 Similar to the Antarctic Bottom water, but slightly less dense
 Floats on top of the Bottom water and the current carries it
down almost to Antarctica
 The deep currents
provide a foundation
of water for the
surface currents to
ride over.
 Movement of the
surface water causes
upwelling, which
brings the deep water
up to the surface.