Deck 7: Ocean Structure and Circulation

Question 1

A water mass at depth in the ocean has temperatures and salinities that are usually determined by the conditions present when the water mass was last at the sea surface.

Answer 1

True

Question 2

The pycnocline of the oceans is usually found at depths exceeding 2000 m.

Answer 2

False

Question 3

The density of Arctic Ocean water is controlled more by salinity than by temperature.

Answer 3

True

Question 4

Wind-driven surface water moves in a complex manner as a function of depth. This is called the ________.

Question 5

Isothermal water is stable and does not overturn.

Question 6

The pycnocline is an area where temperature changes rapidly with depth.

Question 7

Many combinations of salinity and temperature of seawater can produce the same density of seawater.

Question 8

Temperature affects density in the Arctic Ocean more than salinity.

Question 9

Meanders in the Gulf Stream current can pinch off to form warm and cold core ________.

Question 10

The properties of seawater at depth are determined by surface conditions in the area where the water sinks.

Question 11

Usually temperature, salinity, and pressure distributions cause ocean water density to increase with depth.

Question 12

The density of Mediterranean Intermediate Water is influenced more by salinity than temperature.

Question 13

In an area where surface currents converge, the water upwells.

Question 14

Antarctic bottom water has a very narrow range of both salinity and temperature; this water is nearly homogeneous.

Question 15

In the oceans, the zone where density of water changes rapidly with depth is called a pycnocline.

Question 16

Increasing temperature also increases density.

Question 17

Wind blowing across the sea surface can create paired right- and left-handed circulation cells knows as ________ cells, leading to parallel zones of surface convergence and divergence.

Question 18

Water of a lower density usually lies below water of a greater density.

Question 19

Increasing salinity increases density.

Question 20

The large ocean surface-current gyres centered on about 30°N ________.

A) rotate counterclockwise
B) do not rotate
C) have depressed surface elevations
D) rotate clockwise
E) alternate their direction of rotation with the seasons

Question 21

The South Equatorial current of the Pacific Ocean moves surface water from the Southern Hemisphere to the Northern Hemisphere.

Question 22

North Atlantic deep water ________.

A) flows to the south
B) rises toward the surface in the Southern Ocean
C) is formed off Labrador
D) All of these are correct.
E) None of these is correct.

Question 23

The coldest, deepest, densest water in the oceans ________.

A) is formed around Antarctica
B) flows north
C) is Antarctic bottom water
D) All of these are correct.
E) None of these is correct.

Question 24

If very warm and salty sea water is added on top of average seawater, ________.

A) the warm salty water will float at the surface
B) the warm salty water will sink to the bottom and stagnate
C) the warm salty water will sink and move rapidly out of the area
D) an overturn will begin
E) The answer cannot be determined unless the densities of the warm salty water and average sea water are known.

Question 25

The thermocline found in water above 500 m at temperate latitudes disappears and the water column becomes neutral in ________.

A) spring
B) summer
C) fall
D) winter
E) None of these is correct; it does not disappear.

Question 26

A water type having both high salinity and warm temperature but dense enough to be found at about 1000 m in the central North Atlantic has been formed ________.

A) in equatorial regions
B) in the Red Sea
C) in the Mediterranean Sea
D) near Greenland
E) in the Caribbean Sea

Question 27

A surface gyre system in the Southern Hemisphere ________.

A) promotes upwelling and surface depression if it rotates clockwise
B) promotes upwelling and surface elevation if it rotates counterclockwise
C) retards upwelling and decreases surface elevation if rotating counterclockwise
D) retards upwelling and increases surface elevation if rotating counterclockwise
E) Rotation in either direction does not affect upwelling.

Question 28

A good example of thermohaline circulation is found ________.

A) in equatorial regions
B) in the central South Pacific
C) close to Antarctica
D) along the east coast of the United States
E) in the Gulf of Mexico

Question 29

The water type occupying the greatest volume of the Atlantic Ocean is ________.

A) Antarctic bottom water
B) Antarctic intermediate water
C) circumpolar Antarctic water
D) North Atlantic deep water
E) surface water

Question 30

Thermohaline circulation is driven by changes in ________.

A) viscosity
B) surface tension
C) convection
D) pressure
E) density

Question 31

Which of the following are affected by the density of the surface water?

A) Transparency
B) Density layering
C) Convective overturn
D) Density layering and convective overturn
E) All of these are correct.

Question 32

Deep-ocean water in the Atlantic Ocean flows mainly ________.

A) east-west
B) north-south
C) to the right
D) to the left
E) None of these is correct; there is no deep-water flow.

Question 33

If extremely cold fresh water is added on top of seawater, ________.

A) the cold water will float at the surface
B) the cold water will sink to the bottom and stagnate
C) the cold water will sink and move rapidly out of the area
D) an overturn will begin immediately
E) the wind will control the surface mixing

Question 34

In areas of downwelling, a near-surface ________ is unlikely.

A) halocline.
B) pycnocline.
C) thermocline.
D) All of these are correct.
E) None of these is correct.

Question 35

Sigma-t is the oceanographers short-hand for the density of seawater. It is defined as (density − 1.0) × . If the density of seawater is 1.02925 g/cm³, the sigma-t value is

A) 25.29.
B) 2.9925.
C) 0.2925.
D) 29.25.
E) 0.02529.

Question 36

Order the following water bodies from highest to lowest salinity.

A) Mediterranean intermediate water, North Atlantic deep water, Antarctic bottom water
B) North Atlantic deep water, Mediterranean intermediate water, Antarctic bottom water
C) Antarctic bottom water, Mediterranean intermediate water, North Atlantic deep water
D) Mediterranean intermediate water, Antarctic bottom water, North Atlantic deep water
E) Antarctic bottom water, North Atlantic deep water, Mediterranean intermediate water

Question 37

A rapid change in temperature with depth is called a ________.

A) halocline
B) thermocline
C) photic level
D) midwater current
E) pycnocline

Question 38

If two surface water types with the same density but different salinities and temperatures mix, the resulting water will be ________.

A) denser than both parent types
B) less dense than both parent types
C) denser than the more dense parent type
D) less dense than the less dense parent type
E) the same density as the parent types

Question 39

If the density of the water increases with depth, the water column is ________.

A) stagnant
B) unstable
C) stable
D) neutral
E) well mixed

Question 40

Layering in the ocean occurs because ________.

A) surface processes form water layers of differing combinations of salinity and temperature
B) processes at depth add and subtract salt and heat
C) atmospheric processes control conditions at the surface
D) surface processes form water layers of differing combinations of salinity and temperature and atmospheric processes control conditions at the surface
E) All of these choices are correct.

Question 41

Upwelling along the coast of Peru is very seasonal, due to the continually shifting wind patterns.

Question 42

Upwelling occurs along the coast of California when winds blow from the north.

Question 43

The Ekman Spiral causes current speed to increase with depth.

Question 44

Eddies are found at all depths of the oceans.

Question 45

Downwellings occur at surface convergences.

Question 46

Currents in the northern Indian Ocean change direction seasonally.

Question 47

The Indian Ocean gyre rotates counterclockwise.

Question 48

Geostrophic flow occurs when the Coriolis deflection is balanced by an opposite gravitational flow.

Question 49

Prevailing westerly winds cause easterly currents.

Question 50

The clockwise gyre of the Arctic Ocean is driven by the polar easterlies.

Question 51

Southern Hemisphere winds move surface water 90 degrees to the left of the direction of the wind.

Question 52

A convergence of water occurs at the eastern side of each of the main ocean basins as a result of Ekman transport.

Question 53

The highly productive seas along the equator are the result of the tropical convergence located there.

Question 54

Surface eddies can be tracked by satellites.

Question 55

A south wind produces a ________ surface current in the Northern Hemisphere.

A) northern
B) southwest
C) northwest
D) southeast
E) northeast

Question 56

In the Northern Hemisphere, the water surface of the open ocean moves ________.

A) at right angles to the wind
B) against the wind
C) parallel to the wind
D) 45 degrees to the right of the wind
E) 45 degrees to the left of the wind

Question 57

Downwelling is produced by diverging surface currents.

Question 58

The sea surface at the center of the Sargasso Sea is depressed.

Question 59

The North Atlantic gyre rotates counterclockwise.

Question 60

Ocean currents are deflected to a greater degree by the Coriolis effect than by wind systems.

Question 61

The speed of the Florida current is high because ________.

A) the winds are strong at this latitude
B) the water has a high salinity
C) the channel through which it flows is narrow
D) the Coriolis effect is large
E) None of these is correct; it is a slow current.

Question 62

The North Atlantic current is produced by the ________.

A) northeast trade winds
B) southeast trade winds
C) prevailing westerlies
D) polar easterlies
E) seasonal monsoon

Question 63

Which current moves cold water to warm latitudes?

A) Gulf Stream
B) Kuroshio
C) Peru
D) Agulhas
E) Brazil

Question 64

A current meter measures water's ________.

A) speed
B) viscosity
C) direction
D) speed and viscosity
E) speed and direction

Question 65

Currents are more intense on the ________ side of the North Pacific and North Atlantic Oceans.

A) northern
B) southern
C) eastern
D) western
E) None of these is correct; they are not more intense on one side.

Question 66

Currents are less intense on the ________ side of the North Pacific and North Atlantic oceans.

A) north
B) south
C) east
D) west
E) None of these is correct; they are not more intense on one side.

Question 67

A zone of surface divergence is an area of ________ and ________ biological productivity.

A) upwelling; high
B) upwelling; low
C) downwelling; high
D) downwelling; low
E) no vertical motion; average

Question 68

The Gulf Stream forms eddies, or rings, with cold water cores at the ________ edge of the Gulf Stream current.

A) northern
B) southern
C) eastern
D) western
E) either eastern or western

Question 69

When geostrophic flow is achieved, the ________ force is balanced by the ________ force.

A) centrifugal; centripetal
B) Coriolis; centrifugal
C) Coriolis, gravitational
D) gravitational; centrifugal
E) centripetal; centrifugal

Question 70

In the Southern Hemisphere, the speed of the wind-driven water ________ with depth and the water moves to the ________ of the wind.

A) increases; right
B) increases; left
C) decreases; right
D) decreases; left
E) does not change; left

Question 71

The current at the eastern boundary of the Sargasso Sea is the ________ Current.

A) Gulf Stream
B) North Equatorial
C) Canary
D) Greenland
E) Labrador

Question 72

Which current flows south along the west coast of the United States?

A) North Pacific
B) California
C) Japanese
D) Gulf Stream
E) Kuroshio

Question 73

The southeast trade winds directly produce the ________ current.

A) Gulf Stream
B) Equatorial Counter
C) South Equatorial
D) West Wind Drift
E) East Australia

Question 74

A seasonal north wind blowing along the west coast of a landmass in the Northern Hemisphere produces ________.

A) downwelling in winter
B) downwelling in summer
C) upwelling in winter
D) upwelling in summer
E) overturn in all seasons

Question 75

The Atlantic prevailing westerlies drive the ________.

A) Gulf Stream and Canary currents
B) North Atlantic and West Wind Drift
C) Brazil and Benguela currents
D) North and South Equatorial currents
E) None of these is correct.

Question 76

Which current flows north to south along the northeast coast of the United States?

A) Gulf Stream
B) Labrador
C) Canary
D) North Equatorial
E) North Atlantic

Question 77

The average movement of all water affected by the wind is ________ degrees to the ________ of the wind motion in the Southern Hemisphere.

A) 45; right
B) 45; left
C) 90; right
D) 90; left
E) 180; no direction

Question 78

A south wind produces a ________ flowing surface current in the Southern Hemisphere.

A) northwest
B) northeast
C) south
D) southwest
E) southeast

Question 79

A doppler current meter shows an increase in sound frequency if the water flow is ________.

A) moving away from the meter
B) moving toward the meter
C) moving around the meter
D) increasing
E) decreasing

Question 80

Prevailing ________ winds are needed to provide the net movement of surface water seaward along the west coast of North America.

A) northerly
B) easterly
C) westerly
D) southerly
E) seasonal coastal