OCE chapter 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.

Of the following conditions, which is/are related to strong El Niño events?

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

Of the following gyres, which one(s) flow in a counterclockwise direction?

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

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

-Upwelling occurs. -Surface waters move offshore.

Of the following locations, where would upwelling be expected to occur?

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

Why does the west coast of South Africa have high biological productivity?

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

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. Submit

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

Gulf Stream

The thermocline is _________________.

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

Warm ocean currents ___.

are warmer than the surrounding water

Waters along the California coast are colder than those along the mid-Atlantic shore of the U.S. because ______________________ occurs as surface waters move away from the coast.

coastal upwelling

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

Subtropical convergence

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.

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

Western Boundary Current

Deep ocean currents are driven primarily by ________ .

density differences

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

Freezing seawater at ____________ leads to increases in salinity and density.

high latitudes

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

Using this image of the waters adjacent to the East Coast of the United States, match the correct letter to each of the following.

1. D: Warm core ring(s) 2. C: Color for warm water 3. B: Cold core ring(s) 4. A: Color for cold water

What percentage of an icebergs mass is below the waterline?

90%

What depth does Argo floats collect data?

Upper 2,000 meters

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

-Downwelling occurs. -Surface waters move onshore.

Surface ocean currents ___.

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

Which of the following are true of western boundary currents?

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

Which of the following are true of eastern boundary currents?

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

What factor(s) drive(s) Ekman transport?

-wind -Coriolis effect

Use the map of Pacific and Atlantic Ocean currents shown below to correctly identify the following ocean currents and gyres.

1. A: Subpolar gyre 2. H: Antarctic Circumpolar Current (West Wind Drift) 3. I: Brazil Current 4. E: California Current 5. B: Subtropical gyre 6. G: Peru Current 7. F: Canary Current 8. C: Gulf Stream Current 9. D: Benguela Current

The following block diagram shows coastlines in the Northern Hemisphere that are influenced by coastal winds (not shown). Based on the flow of surface waters due to Ekman transport, identify the correct coastal wind direction in each diagram.

1. B: Wind blowing parallel to the coast and toward the bottom of the diagram 2. A: Wind blowing parallel to the coast and toward the top of the diagram

The diagram below shows a generalized cross-sectional view across the Atlantic Ocean. Correctly match the letters with the corresponding water masses and associated features.

1. D: Antarctic Bottom Water 2. C: Seasonally warm water 3. G: Upwelling 4. A: Thermocline and pycnocline 5. E: Antarctic Intermediate Water 6. F: North Atlantic Deep Water 7. B: Warmest water

The image below is a block diagram showing the Pacific Ocean during an El Niño event. Correctly match the letters with the corresponding features.

1. D: Low atmospheric pressure 2. A: Thermocline 3. E: Pacific Warm Pool 4. C: High atmospheric pressure 5. B: Walker Circulation Cell (reversed direction)

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

Western intensification causes:

All the above effects are the result of western intensification. Submit

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. Submit

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

Greenland and Antarctica

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

Palm trees associated with the subtropics can be found at the northern tip of the British Isles in Scotland. This is due to the transfer of heat from the ________________.

North Atlantic current.

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

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

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. Submit

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.

_____________________ is caused by density changes near the poles and equator.

Thermohaline circulation

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

Downwelling can result from __________.

converging surface currents

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

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