Wind-driven circulation

Question 1

2 main factors in producing ocean currents

Answer 1

winds and density differences

Question 2

Ekman spiral

Answer 2

top layer driven forward by wind
each layer moved by friction
each succeeding layer moves more slowly and at an angle that the layer above
occurs until water motion becomes negligible

Question 3

Ekman transport

Answer 3

the net flow of water over the Ekman spiral is at
90 deg to the RIGHT of prevailing wind in N hem
90 deg to the LEFT … in S hem

Question 4

upwelling

Answer 4

upward movement of water associated with divergence at surface
illustrates mass continuity

Question 5

downwelling

Answer 5

downward movement of water associated with convergence at surface
illustrates mass continuity

Question 6

Equatorial upwelling

Answer 6

South Equatorial Current diverges around Equator due to Coriolis Effect
- water N of Equator verges N (right) and water S verges S (left)
most pronounced in Pacific
Upwelling waters rich in nutrients

Question 7

Southern Ocean upwelling

Answer 7

Upwelling around 60 deg S

Due to divergence of W and E winds

Question 8

Coastal upwelling and downwelling

Answer 8

Winds blowing parallel to coast cause coastal upwelling and downwelling
Due to Coriolis effect, Ekman transport is offshore or shoreward
winds blowing offshore or shoreward can also cause coastal upwelling

Question 9

Doming and depression of ocean surface

Answer 9

Ekman transport an cause divergent and convergent flows
can cause a pressure gradient force
water pressure higher where water piles up - force of gravity pulls water down the slope (against pressure gradient)
coriolis effect balances pgf
= geostraphic balance and current

Question 10

Geostrophic balance

Answer 10

pressure gradient force vs coriolis effect
prevents spiraling
geostrophic gyres form little hills

Question 11

Western intensification

Answer 11

symmetry between atm and oceanic circulations
asymmetry between E ans W sides of ocean basins with major differences between E and W boundary currents (western offset) and doming of ocean surface on W side

Question 12

Six great current circuits

Answer 12

North Atlantic gyre
North Pacific gyre
South Atlantic gyre
South Pacific gyre
Indian Ocean gyre
ACC ( not a gyre because it doesn't flow around the periphery of a basin)

Question 13

W vs E boundary currents

Answer 13

see table

Question 14

Transverse currents

Answer 14

due to wind stress in tropics and mid lats
westward flow driven by trade winds
easterward flow bt mid lat westerlies
links E and W boundary currents
shallow and broad

Question 15

Impact of surface currents on weather and climate

Answer 15

warm water from tropics toward high lats
at high lats, heat transferred to atm
water cools and moves back to low lats
cyclical
at low lats on ocean’s E boundaries, cold waters flow along coast
wind direction and relative temp between ocean and air influence coastal climates