OCE CH 7

Recall that global winds impact the direction of surface ocean currents. Examine the following map showing the Atlantic Ocean off the west coast of Africa. The direction of the surface current and the prevailing wind do not coincide. What can explain this discrepancy?

-Because the current is located in the Southern Hemisphere, the subtropical gyre pulls the current in a counterclockwise direction. -The Coriolis effect deflects ocean currents in the Southern Hemisphere to the left due to Earth's rotation.

On a west coast in the Northern Hemisphere, what happens to surface waters when winds blow from the south? Choose all that apply.

-Downwelling occurs. -Surface waters move onshore.

Of the following methods, which are indirect methods for measuring currents? Choose all that apply.

-Dynamic topography -Pressure gradients -Doppler flow meter

Of the following conditions, which is/are related to strong El Niño events? Choose all that apply.

-Higher sea levels in the eastern Pacific Ocean associated with warmer water -Increased abundance of hurricanes in the eastern Pacific Ocean -Increase in sea-surface temperatures and destruction of coral reefs in the eastern Pacific Ocean

Which of the following statements is/are true regarding subtropical convergence? Choose all that apply.

-Subtropical convergence causes a bulge of surface water that can be as high as 2 meters. -Subtropical convergence produces a hill of piled up water in the center of each gyre in the northern hemisphere that is deflected towards the west. -Subtropical convergence is caused by the clockwise rotation of each gyre in the northern hemisphere.

On a west coast in the Northern Hemisphere, what happens to surface waters when winds blow from the north? Choose all that apply.

-Upwelling occurs. -Surface waters move offshore.

Of the following locations, where would upwelling be expected to occur? Choose all that apply.

-Where there is a sharp bend in a coastline -Where seamounts or tablemounts are present -In areas of diverging surface currents

Surface ocean currents ___. CHOOSE ALL THAT APPLY.

-are influenced by Coriolis effect -are driven by winds -form large rotating gyres in the major ocean basins

Which of the following are true of western boundary currents? Choose all that apply

-fast, as compared to eastern boundary currents -deep, as compared to eastern boundary currents

Actual geostrophic flow is created by which of the following? Choose all that apply.

-friction -gravity -Coriolis effect

Of the following gyres, which one(s) flow in a counterclockwise direction? Choose all that apply.

-indian Ocean Subtropical Gyre -Northern Hemisphere Subpolar Gyres -South Pacific Subtropical Gyre -South Atlantic Subtropical Gyre

Why does the west coast of South Africa have high biological productivity? Choose all that apply.

-lots of coastal upwelling -high concentrations of nutrients in the surface water

Which of the following are true of eastern boundary currents? Choose all that apply.

-wide, as compared to western boundary currents -they flow along the more gradual slope of the hill of water -weak, as compared to western boundary currents

What factor(s) drive(s) Ekman transport? Choose all that apply.

-wind -Coriolis effect

In which direction does the surface current move in relation to the wind in the Southern Hemisphere?

45 degrees to the left

Using the T-S diagram shown above, if a water mass has a density of 1.0280 g/cm3 and a salinity of 35.3 ppt, what is its temperature?

5 degrees Celsius

What percentage of an icebergs mass is below the waterline?

90%

Western intensification causes:

All the above effects are the result of western intensification.

Peru's residents are familiar with ENSO as it brings a warm current that reduces populations of which animal?

Anchovies

In locations where North Atlantic Deep Water, Antarctic Bottom Water, and Antarctic Intermediate Water are all found, how would they be arranged vertically in the water column?

Antarctic Bottom Water would be on the bottom, North Atlantic Deep Water would be in the middle, and Antarctic Intermediate Water would be on the top.

Which of the following is the only current that completely circumscribes Earth?

Antarctic Circumpolar

Which of the following currents contributes to the South Western United States being arid?

California Current

Which of the following is true for downwelling?

Carries dissolved oxygen to the deep-sea floor

Water with which of the following characteristics would be the densest?

Cold water with high salinity would be the densest.

Which conditions in the ocean promote high productivity?

Cold water, rich nutrients

Why do the lengths of the arrows in the Ekman spiral get shorter and shorter as you move deeper into the water column?

Deeper water moves at a slower speed due to friction.

Which method would be most appropriate for directly measuring the flow rate of the Gulf Stream?

Drift bottles

The California Current is an example of which of the following types of currents?

Eastern Boundary Current

The area in the enclosed rectangle in the false-color map of sea surface temperatures is an example of which of the following features?

Eddies

The world's two main iceberg-producing regions are ________.

Greenland and Antarctica

Which of the following currents contributes to the South Eastern United States being humid?

Gulf Stream

What is the Walker Circulation Cell?

It is the path that air takes as it moves from high to low pressure, and back to high pressure, in the South Pacific under normal conditions.

Which swift-flowing surface current in a major subtropical gyre transports a large volume of warm water from the equator toward the mid-latitudes?

Kuroshio Current

Which of the following water masses has the highest average salinity?

Mediterranean Intermediate Water

The North Atlantic Current is an example of which of the following types of currents?

Northern Boundary Current

Which of the following is a direct method for measuring surface currents?

Propeller flow meter

Which of the following methods are used to measure ocean surface currents directly?

Radio-transmitting float bottles

The West Wind Drift is an example of which of the following types of currents?

Southern Boundary Current

The deepest and densest water mass in the world ocean is formed in the __________________.

Southern Ocean

The observation of a hill of water within all subtropical gyres is an example of which of the following?

Subtropical convergence

What would you expect weather to be like on the eastern coast of Australia if the western coast of South America were experiencing unusually warm, wet weather?

The eastern coast of Australia would be experiencing unusually dry weather.

In a severe warm phase of the El Niño-Southern Oscillation (ENSO), fisheries' productivity on the west coasts of the Americas is dramatically reduced. Which stage of ENSO would come just before the fisheries' collapse?

The thermocline deepens in eastern boundary currents of the Pacific Ocean subtropical gyres.

Which of the following is true of surface water circulation near Antarctica?

Two circumpolar currents dominate it, one current that moves water to the east and one current that moves water to the west

What depth does Argo floats collect data?

Upper 2,000 meters

The Agulhas Current is an example of which of the following types of currents?

Western Boundary Current

In the figure above, if this is a western-facing coast of the Northern Hemisphere, which wind pattern would cause coastal downwelling?

Wind C

In the figure above, if this is a western-facing coast of the Southern Hemisphere, which wind pattern would cause coastal upwelling?

Wind C

Why does upwelling occur along the west coast of South America under normal conditions?

Winds moving westward in the South Pacific drive ocean currents toward the west; deep water rises to replace water driven westward.

The thermocline is _________________.

a steep temperature gradient in the ocean that separates deeper cold water from warmer upper water

Warm ocean currents ___.

are warmer than the surrounding water

Downwelling can result from __________.

converging surface currents

Deep ocean currents are driven primarily by ________ .

density differences

Equatorial currents that are part of the subtropical gyres flow ___. Equatorial counter currents between the gyres flow ___ .

east to west; west to east

Which direction do ocean currents in the South Pacific move under El Niño conditions?

eastward

During winter months, monsoon winds over the Indian Ocean ________.

flow from land to sea and are dry

Cool ocean currents ___.

generally flow from high latitudes towards the equator

Which type of current flow moves in a circular path around a subtropical convergence, reflecting Ekman transport, gravity, and the Coriolis effect?

geostrophic circulation

Deep-water currents move ________ volumes of water and are much ________ than surface currents.

larger; slower

What is the overall effect of the stronger than normal trade winds typical of La Niña conditions?

lowering of the South Pacific ocean temperature from normal conditions

Ocean surface currents transfer about ________ of the total amount of heat from the tropics to the poles.

one-third

The subtropical gyres ___.

play a large role in climate

Deep ocean currents ___.

result from changes in water density (due to temperature and salt content)

Records indicate that the ocean is warming faster in the Arctic polar regions than elsewhere. If that continues, a possible consequence could be __________.

slowing of deep-ocean circulation, resulting in lower oxygen levels in deep water

The thickness of sea ice is limited primarily by __________.

the insulating nature of the ice itself

The El Niño Southern Oscillation can best be described as:

the relationship between sea surface temperature and changing atmospheric pressure

What causes western intensification?

the rotation of Earth from west to east

What is the Southern Oscillation?

the swapping of high and low pressure zones in the South Pacific under El Niño conditions

The Ekman spiral is caused by:

the wind and the Coriolis effect

In the figure above, depicting a hypothetical wind direction in an ideal world. The iceberg broke off from the Greenland Ice Sheet and floated into the ocean. Under the prevailing wind conditions, in which direction would the iceberg be pushed?

toward D

Refer the figure above. In which direction would the entire surface current underneath the Greenland iceberg be expected to travel?

toward E

Equatorial currents are driven by the:

trade winds

Under which conditions are droughts and wildfires common in Australia?

under El Niño conditions

Surface waters are pushed away from land and replaced by nutrient-rich bottom water through:

upwelling.

Diverging surface waters are areas of ________ and ________ productivity

upwelling; high

Surface ocean currents are driven primarily by ________ and modified by ________.

wind; the Coriolis effect and land