Notes on “Ocean Currents”
Earth/Space
S.W.B.A.T.
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Explain how winds and the Coriolis
effect influence surface currents
Discuss the temperatures of coastal
waters
Describe density currents and how
they affect Earth
Surface Currents
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Ocean currents are
like rivers within the
oceans
Surface Currents water that moves
horizontally or
parallel to Earth’s
surface by wind
Surface Currents
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Only a few hundred
meters of surface
water is moved
Some seeds and plants
are carried between
continents by surface
currents
Major Surface Currents of Earth’s Oceans
Surface Currents
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Because Earth rotates west to east
surface winds causes water to shift
Coriolis Effect - shifting of winds &
waters due to Earth’s rotation
Surface Currents
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Wind and surface currents will
deflect to the right (or “clockwise”) in
the northern hemisphere and to the
left (counter-clockwise) in the
southern hemisphere
Coriolis Effect or “Force”
Video (2:12) “Coriolis Effect Explained”
Surface Currents
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Gulf Stream – flows
up the U.S. east coast
and keeps Britain &
Northern Europe’s
climate mild
The Gulf Stream is
the world’s most
powerful ocean
surface current
Surface Currents
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Satellites can track currents based on
ocean temperature
Surface currents can also be tracked
by using messages in bottles and other
flotation devices
Ocean Surface Temperatures - Satellite Data
Surface Currents
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Warm currents (red) originate near
the equator and flow towards the poles
This distributes heat into the
atmosphere and influences climate
Cold currents (blue) flow towards the
equator & heats up creating a cycle
Upwelling
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Upwelling occurs
when deep, cold
ocean water is
brought to the
surface
Winds along some
coasts will move
warm water away
from the surface
Upwelling
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Cold bottom water will rise up to take
the place of the warmer water
This water contains organisms that
have died, sank to the bottom and
decayed
Nutrients from upwelling attract fish
Areas of Upwelling (in Red) and Major
World Fisheries
Density Currents
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Density currents – when a mass of
seawater circulates because of density
differences
Density increases with higher salinity
Density also increases with a decrease in
temperature
Also known as “thermohaline” currents
(“thermo” = temperature; “haline” =
salinity)
Density Currents
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Changes in temperature
and salinity work
together to create
density currents
These currents move
very slowly and can
take many years to
circulate
Density Currents
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Global Ocean Conveyor Belt – starts in
the winter in the arctic regions
Seawater freezes leaving behind highsalinity water that sinks
This deep-ocean conveyor belt takes
about 1000 years to circulate the Earth
once!
Deep-Water Global Ocean Conveyor Belt
Video (2:40) “Ocean Odyssey: Density
Current”
Density Currents
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Mediterranean water is very high in
salinity due to a warm climate and
evaporation
This causes an intermediate layer to form
on top of the cold water in the Atlantic
Density Currents
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Thermohaline (density) currents are very
important in replenishing nutrients from
warmer surface waters
These currents also help in regulating
global climate
Global warming may affect density
currents causing further climate change
Class Activity
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A river flows into the ocean
Predict what will happen to this
layer of fresh-water
Explain your prediction