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 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. Ocean Currents Lecture Notes (Topic 9A) page 2 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 Equator California Land
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
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. Ocean Currents Lecture Notes (Topic 9A) page 6 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 65 o N? b. What is the direction of the current in the middle of the Atlantic Ocean at 45 o N? c. What is the direction of the current along western coast of Africa at 30 o N? 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 30 o S? f. What is the direction of the ocean current in the middle of the Pacific Ocean at 55 o S? g. What is the direction of the ocean current in the middle of the Pacific Ocean at 65 o S?
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.
Practice Questions: Ocean Current Patterns Answer Key Ocean Currents Lecture Notes (Topic 9A) page 10 Practice Questions: Upwelling Patterns Answer Key