Ocean Circulation

Question 1

Boundary currents=
Give 2 examples

Answer 1

very large ocean currents that run along a continent
eg
- gulf stream (North America’s east coast)
- kuroshio current (Japan- pacific ocean)

Question 2

What are gyres? Where are the main 4?

Answer 2

massive circular or spiraling circulation patterns thousands of km in diameter that are bordered by permanent boundary currents
- 2 in atlantic, 2 in pacific

Question 3

Eddies=

Answer 3

smaller circular pockets of water that break off from a boundary current
- can also be seen in rivers!)

Question 4

T/F for each:
1. eddies are temporary
2. Eddies are always cold water
3. Eddies are important for dispersal of animals and plankton

Answer 4

1. true
2. false- they can be warm or cold, it depends in the boundary current
3. true

Question 5

Give an example of why gyres are so important

Answer 5

loggerhead sea turtles
- they stay within the north Atlantic subtropical gyre because the water is warmer

where would they go if there wasn’t a gyre!

Question 6

where do drifting plastics end up in the ocean?

Answer 6

in doldrums, where there’s little wind
- gyres push it all to a central location

Question 7

t/f

the circumpolar current around Antarctica is a boundary current

Answer 7

false
it’s not!

Question 8

___ drives the ocean currents
how?

Answer 8

the sun

because it warms the earth unequally, which drives atmospheric circulation (winds), which drives ocean currents

Question 9

there is a ___ of radiation between 40 deg S and 40 deg N and a ____ poleward of there
What does this cause?

Answer 9

surplus (near the equator)
deficit (poles)

Causes winds (earth wants to be at equilibrium)

Question 10

Explain the 3 circulation pattern cells on earth

Answer 10

Hadley cell: hot air rises at equator, moves toward poles, and sinks as it cools

Ferrel Cell: air moves northward along the surface, then rises (hits polar cell) and moves back south

Polar Cell: at the poles. Cold air sinks at the very top (furthest south or north) and rises when it reaches the ferrel cell

Question 11

Where there’s rising air, what pressure will the surface experience?

Answer 11

rising warm air= low pressure (rising air ‘takes pressure off of the earth”)

Question 12

What 3 things cause the Coriolis force?

Answer 12

1. earth’s rotation- objects @ equator move faster than objects at the poles
2. gravity- objects are pulled towards earth by gravity
3. centrifugal force- spins objects quickly around the earth

Question 13

in the northern hemisphere, the coriolis force apparently deflects moving objects to the ____

Answer 13

right

Question 14

in the southern hemisphere, the coriolis force apparently deflects moving objects to the ____

Answer 14

left

Question 15

winds travel from ___ to ___ pressure

Answer 15

high to low

Question 16

the equator is a region of ____, meaning:

Answer 16

convergence
winds come together, causes lots of rani and clouds at the equator

Question 17

the __ drives oceanic circulation through the circulation of the ____

Answer 17

sun
atmosphere (winds)

Question 18

t/f
Ekman transport leads to downwelling

Answer 18

false

leads to upwellings! brings cold water up

Question 19

Ekman transport is caused by ___, and causes a net __ degree shift (to the __ in N hemi, and ___ in S hemi)

Answer 19

friction (b/w wind/ water and water/ water)

90 degree

right in N
left in S

Question 20

a wind along a coast generates an ekman transport vector ____

Answer 20

offshore

can happen anywhere in the ocean but more noticeable along the coast

Question 21

Explain why phytoplankton blooms happen where ekman transport is occurring

Answer 21

ekman transport occurs and nutrient-rich deep water moves to surface to replace the water transported offshore (upwelling)

add sunlight, and these nutrient rich waters feed phytoplankton blooms

Question 22

t/f

enso can result in a 5m difference in sea level on east or west pacific

Answer 22

false

1m difference

Question 23

What is the ENSO cycle?

Answer 23

a periodic change in the strength of the equatorial current (every 2-7 years, but quite erratic) in the winter

Question 24

In a ‘normal’ year (La Nina):
- warm water in the equatorial current moves _____
- this causes strong ___ off peru
- there is a steep ____, meaning cold water is brought to the surface
- deep water brings ____ to the surface
- this generates ____ ____, which increases ____, which increases _____

Answer 24

• westward, towards AUS
• upwelling (ekman)
• thermocline
• nutrients
• phytoplankton blooms, zooplankton, fish (=good fisheries in peru!)

Question 25

In an El Nino year:

• the equatorial current ____
• warm water stays in the eastern pacific and slooshes back across to ___
• this causes ___ of the water
• no ____= no nutrients brought to the surface= bad fisheries

Answer 25

• slackens (we don’t know why)
• peru
• stratification (layers are very shallow/ no thermocline/ mixing)
• upwelling

Question 26

thermohaline circulation is driven by ____ and _____ difference

Answer 26

temperature and salinity

Question 27

high latitude surface waters have ___ salinity and ___ temperature= ___ density

Answer 27

high salinity

low temp

high density

Question 28

waters at the poles ___ and move to lower latitudes at depth. What does this form?

Answer 28

sink

a massive ocean river from arctic to Antarctic and back = global conveyor belt