Ocean Currents Lecture Notes (Topic 9A) – page 1
Ocean Currents Lecture Notes
Surface Currents
Ocean Currents (What is an ocean current? How is a current different from a wave?)
The water in an ______________________________ travels from place to place, like a river.
The water below a __________________ goes in small circles, and
thus does not really go anywhere.
What is a gyre?
Ocean currents that travel in a big ___________________________________ that
goes _________________ in some places and __________________ in some places.
Why does the water move in gyres? (What is required? What is necessary?)
Global __________________ push ocean water ______________ at some latitudes and
______________ at other latitudes. If the water runs into ___________, it has to move north
or south to make room for water that the winds keep pushing to the coast. Eventually the
water reaches a latitude where it is pushed away from the coast and back the way it came.
Note: The currents do NOT always move in the same direction as the Ekman Transport.
The winds TRY to push the water in the directions shown by Ekman Transport arrows,
but other things (e.g., land, water, other ocean currents) get in the way, so the water
often moves is a different direction than the Ekman Transport.
Ocean Currents Lecture Notes (Topic 9A) – page 2
Ocean Circulation Activity
On the maps below, sketch the overall motion
of the water (e.g., gyre) given the winds in map.
If there is no gyre, sketch the currents that
would be created.
Note: “NH” indicates that the winds
blow in the northern hemisphere,
while “SH” indicates that the winds
blow in the southern hemisphere.
Then, explain why the ocean currents go in the directions that you sketched.
In other words, explain what pushes the water in the directions that you indicated on the map.
Note: Do NOT show the Ekman transport (the direction that the water is pushed by the wind);
instead, show the overall currents that result from the Ekman transport.
Ocean Currents Lecture Notes (Topic 9A) – page 3
Review Questions
Which way should the gyre go?
(Southern Hemisphere)
a. clockwise
b. counterclockwise
c. no gyre
What kind of boundary current flows
along the east coast of South America?
a. Eastern B.C.
b. Western B.C.
What is the direction of the current
along the east coast of South America?
Does it carry warm water or cold water?
a. north, warm water
b. north, cold water
c. south, warm water
d. south, cold water
Ocean Currents Lecture Notes (Topic 9A) – page 4
Currents and Life
Effects of Upwelling
Temperature the Surface of the Ocean:
Salinity of the Surface of the Ocean:
Life at the Surface of the Ocean:
Upwelling Locations (Where is upwelling common?)
Coast of California
Equator
Land
California
Land
Equator
Ocean Currents Lecture Notes (Topic 9A) – page 5
Review Questions
Which of the following are examples of upwelling?
a. Two ocean currents come together, and the water “piles up.”
b. Water comes up to replace water pushed away from a coast by winds.
c. Wave orbitals stir up water from below.
In which of the following places would you expect to find upwelling?
a. middle of Antarctic Ocean
b. middle of Arctic Ocean
c. center of subtropical gyres
d. east coast of South America
e. on the Equator
f. west coast of Africa
Ocean Currents Lecture Notes (Topic 9A) – page 6
Upwelling & Downwelling Activity
On the maps below, sketch the direction(s)
that water will be pushed by the winds in map.
In other words, sketch the Ekman Transport.
Note: “NH” indicates that the winds
blow in the northern hemisphere,
while “SH” indicates that the winds
blow in the southern hemisphere.
Circle any areas of upwelling or downwelling (if there are any), and label your circles.
(In other words, write “upwelling” or “downwelling” on them).
How can you tell that upwelling or downwelling is happening in these places?
Explain your reasoning.
Then, explain how or why upwelling or downwelling happens under these conditions.
Ocean Currents Lecture Notes (Topic 9A) – page 7
Practice Questions: Ocean Currents at specific latitudes and longitudes
a. What is the direction of the ocean current along the east coast of Greenland at 65oN? _____________
b. What is the direction of the current in the middle of the Atlantic Ocean at 45oN?
_____________
c. What is the direction of the current along western coast of Africa at 30oN?
_____________
d. What is the direction of the current in the middle of the Atlantic Ocean at the Equator? ____________
e. What is the direction of the current along the west coast of South America at 30oS?
_____________
f. What is the direction of the ocean current in the middle of the Pacific Ocean at 55oS? _____________
g. What is the direction of the ocean current in the middle of the Pacific Ocean at 65oS? _____________
Ocean Currents Lecture Notes (Topic 9A) – page 8
Practice Questions: Ocean Current Patterns
Given the winds shown below, sketch the ocean currents that would flow in each map.
NH indicates a location in the northern hemisphere.
SH indicates a location in the southern hemisphere.
Ocean Currents Lecture Notes (Topic 9A) – page 9
Practice Questions: Upwelling Patterns
Given the winds shown below, sketch the direction of Ekman Transport for each wind belt.
NH indicates a location in the northern hemisphere.
SH indicates a location in the southern hemisphere.
Ocean Currents Lecture Notes (Topic 9A) – page 10
Practice Questions: Ocean Current Patterns – Answer Key
Practice Questions: Upwelling Patterns – Answer Key