Deck 7: Ocean Structure and Circulation

Question 1

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

Answer 1

True

Question 2

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.

Answer 2

D

Question 3

Isothermal water is stable and does not overturn.

Answer 3

True

Question 4

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

Question 5

Increasing salinity increases density.

Question 6

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

Question 7

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

Question 8

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

Question 9

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

Question 10

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 11

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

Question 12

Temperature affects density in the Arctic Ocean more than salinity.

Question 13

Increasing temperature also increases density.

Question 14

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

Question 15

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

Question 16

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

Question 17

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

Question 18

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

Question 19

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

Question 20

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

Question 21

In areas of downwelling, there is not likely to be a near-surface

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

Question 22

A water type having both high salinity and warm temperature but dense enough to be found at about 1000m 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 23

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 24

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

Question 25

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 are correct.

Question 26

A rapid change in temperature with depth is called a

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

Question 27

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) All of these are correct.
E) surface processes form water layers of differing combinations of salinity and temperature and atmospheric processes control conditions at the surface.

Question 28

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 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

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 31

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 32

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 in creases surface elevation if rotating counterclockwise.
E) Rotation in either direction does not affect upwelling.

Question 33

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 are correct.

Question 34

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 35

Sigma-t is the oceanographer's short-hand for the density of seawater. It is defined as (density - 1.0) × 103. If the density of seawater is 1.02925g/cm³, the sigma-t value is

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

Question 36

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 37

Thermohaline circulation is driven by changes in

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

Question 38

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 U.S.
E) in the Gulf of Mexico.

Question 39

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 are correct; there is no deep-water flow.

Question 40

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

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

Question 41

Eddies are found at all depths of the oceans.

Question 42

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

Question 43

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

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

Question 44

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

Question 45

The Ekman spiral causes current speed to increase with depth.

Question 46

Prevailing westerly winds cause easterly currents.

Question 47

Downwellings occur at surface convergences.

Question 48

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

Question 49

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

Question 50

The North Atlantic gyre rotates counterclockwise.

Question 51

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

Question 52

Downwelling is produced by diverging surface currents.

Question 53

Surface eddies can be tracked by satellites.

Question 54

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 55

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

Question 56

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

Question 57

Currents in the northern Indian Ocean change direction seasonally.

Question 58

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

Question 59

The Indian Ocean gyre rotates counterclockwise.

Question 60

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

Question 61

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 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 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 65

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 are correct; it is a slow current.

Question 66

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 is correct.

Question 67

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 68

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

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

Question 69

Which current flows south along the west coast of the U.S.?

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

Question 70

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

Question 71

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 72

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 73

The North 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 are correct.

Question 74

A current meter measures water

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

Question 75

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 are correct; they are not more intense on one side.

Question 76

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 77

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 78

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 79

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 80

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 are correct; they are not more intense on one side.