Oceans Midterm #2 | Chapter 9

Countercurrents or undercurrents: Flow on the surface in the opposite direction from the main current.

Countercurrents

Equatorial currents are typically accompanied by __________________________ (countercurrents or undercurrents).

Countercurrents

What gyre is a series of four interconnecting currents with different flow characteristics and temperatures?

North Atlantic gyre

In the _____________________ (Northern or Southern) hemisphere, coastal upwelling can be caused by winds from the north blowing along the west coast of a continent.

Northern

Equatorial upwelling is most pronounced where?

Pacific

Equatorial upwelling happens during a. El Nino Year b. Non-El Nino Year

B

High atmospheric pressure south of Alaska blocks the storm track. a. El Nino Year b. La Nina Year

B

Cold-cored eddies rotate _____________________ (clockwise or counterclockwise).

Counterclockwise

Of the six great circular currents in the world's ocean, how many are geostrophic gyres?

5

Seawater flows in how many great surface circuits (gyres)?

6

Distribute nutrients and scatter organisms. a. Surface currents b. Thermohaline currents

A

In the Northern Hemisphere, surface currents flow to the ________ of wind direction; in the Southern Hemisphere, surface currents flow to the ________. a. right; left b. right; right c. left; left d. left; right

A

Influence weather and climate. a. Surface currents b. Thermohaline currents

A

Low atmospheric pressure south of Alaska allows storms to move unimpeded to the Pacific coast. a. El Nino Year b. La Nina Year

A

Surface waters of the central and eastern Pacific become warmer, and storms over land may increase. a. El Nino Year b. Non-El Nino Year

A

The Westerlies drive which current? a. North Atlantic Current b. North Equatorial Current

A

The circulation of water at great depths is driven by: a. density. b. temperature only. c. surface winds. d. salinity only.

A

The flow direction of surface ocean currents is due primarily to: a. the wind. b. the sun. c. gravity. d. the moon.

A

The resulting weather is wet and cool to the south and warm and dry to the north. a. El Nino Year b. La Nina Year

A

The upward motion of water. This motion brings cold, nutrient rich water towards the surface. a. Upwelling b. Downwelling

A

These are warm, narrow, deep, fast currents found at the western boundaries of ocean basins. a. Western Boundary currents b. Eastern boundary currents

A

Transfer heat from tropical to polar regions. a. Surface currents b. Thermohaline currents

A

Warm water flows to a. Higher latitudes b. Low latitudes

A

When the Southern Oscillation develops, the trade winds diminish and then reverse, leading to an eastward movement of warm water along the equator. a. El Nino Year b. Non-El Nino Year

A

Wind driven movement of the uppermost water in the ocean primarily above the pycnocline. a. Surface currents b. Thermohaline currents

A

What forms in the center of a gyre?

A hill of water (2 m high)

Do bottom currents flow around or over obstructions?

Around

Density driven currents that are slow, deep currents affecting the vast bulk of the seawater below the pycnocline. a. Surface currents b. Thermohaline currents

B

Downward motion of water. It supplies the deeper ocean with dissolved gases. a. Upwelling b. Downwelling

B

Eastern boundary currents: a. are relatively deep, narrow and fast. b. carry cold water toward the equator. c. are located east of the continents. d. are difficult for sailors to navigate.

B

Normally the air and surface water flow westward, the thermocline rises, and upwelling of cold water occurs along the west coast of Central and South America. a. El Nino Year b. Non-El Nino Year

B

Of the great current circuits in the world ocean, there are ________ in the Northern Hemisphere and ________ in the Southern. a. 3; 3 b. 2; 4 c. 4; 2 d. 6; 6

B

The Trade Winds drive which current? a. North Atlantic Current b. North Equatorial Current

B

These currents are cold, shallow, broad, slow, and their boundaries are not well defined. a. Western Boundary currents b. Eastern boundary currents

B

Winds veer north, lose their warmth over Canada, and sweep down as cold blasts. The Pacific Northwest gets its usual rain, but the southwest suffers drought. a. El Nino Year b. La Nina Year

B

Western boundary currents: a. are relatively shallow, broad and slow. b. carry cool polar water toward the equator. c. transport enormous volumes of water. d. transport water in a diffuse, ill defined stream.

C

Where do water masses butt against each other?

Convergence zones

Does the heavier water slide on top of or beneath the lighter water?

Beneath

Where is the densest water?

Bottom

What do bottom currents follow?

Bottom topography

In the southern hemisphere, the great currents (gyres) move in a _________________ pattern. a. Figure-eight b. Clockwise c. Counterclockwise d. Random

C

The flow direction of surface ocean currents is due primarily to: a. the moon. b. gravity. c. the wind. d. the sun.

C

The most important current for promoting water exchange among all three oceans is the: a. South Pacific Gyre. b. Gulf Stream. c. Antarctic Circumpolar Current. d. Arctic Convergence.

C

The global pattern of deep circulation resembles a vast what?

Conveyor belt

The effect of Edman spiraling and the Coriolis effect cause the water within a gyre to move in what type of pattern?

Circular

Warm-cored eddies rotate ______________________ (clockwise or counterclockwise).

Clockwise

Water turns ________________ (clockwise or counterclockwise) to form the dome, then descends, depressing the thermocline.

Clockwise

Areas of downwelling are often low in nutrients and therefore relatively low in biological productivity.

Coastal downwelling

Wind blowing from the south along a Northern hemisphere west coast for a prolonged period can result in downwelling.

Coastal downwelling

What are bottom currents called?

Contour currents

Surface currents extend to what depth in the ocean? a. 10 meters (33 feet) b. 100 meters (330 feet) c. 200 meters (660 feet) d. 400 meters (1,300 feet)

D

The surface ocean gyres: a. have water moving in the same direction from the sea surface to the bottom. b. are confined on all sides by the continents. c. have the strongest currents on their eastern sides. d. are primarily the result of wind patterns.

D

When pressure differences in the western and eastern Pacific cause the trade winds to reverse it is called: a. El Niño. b. Corriente del Niño. c. La Niña. d. Southern Oscillation.

D

Which one is evidence that strong, localized bottom currents exist? a. Ripple marks in sediments b. Scour lines c. Erosion of rocky outcrops on deep-ocean floors d. All of the above

D

A body of water can be thought of as a set of layers. The top layer is driven forward by the wind, and each layer below is moved by friction.

Ekman spiral model

What is the hill formed by?

Ekman transport

The great quantities of dense water sinking at polar ocean basin edges must be offset by what?

Equal quantities of water rising elsewhere

Nutrient-rich water rises near the what?

Equator

True or false: The surface currents on the eastern side of the oceans are faster than the currents on the western sides.

False

True or false: The vertical movement of water due to changes in temperature and salinity is called Ekman transport.

False

Bottom currents are relatively _____________ (fast or slow) and dense.

Fast

What do water masses do when they meet?

Flow above or below each other

Gyres in balance between the pressure gradient (hill) and the Coriolis effect.

Geostrophic gyres

Each succeeding layer moves with a _____________ (slower or faster) speed and at an angle to the layer immediately above it.

Slower

Water masses of the Atlantic move ___________ (slowly or fast), propelled by gravity.

Slowly

Why doesn't it all flow to the center of the gyre and pile up into a hill?

Some of it does but this is resisted by the gravity-powered movement of water down this pressure gradient

What are the two major types of ocean currents?

Surface and thermohaline

What are the 5 common water masses in temperate and tropical latitudes?

Surface water, central water, intermediate water, deep water, bottom water

What are the four forces that make up a gyre?

Surface winds, sun's heat, Coriolis effect, gravitiy

Where is density stratification of the ocean the most pronounced?

Temperate and tropical latitudes

Name a Eastern boundary current.

The California Current

Name a Western boundary current.

The Gulf Stream

The movement of water due to differences in density is called ______________________ ____________________.

Thermohaline circulation

Surface currents distribute what worldwide?

Tropical heat

True or false: Contour currents speed varies but can be as slow as 1 to 2 meters per day or as fast as surface currents.

True

True or false: Current flow in the center of gyres is minimal.

True

True or false: Eddies form at the boundary between swift current and the quiet adjacent waters.

True

True or false: Hundreds of years can pass before water masses complete a circuit or blend to lose their identities.

True

True or false: In reality, this deflection barely reaches 45 degrees.

True

True or false: In the North Pacific (Northern Hemisphere), Gyre surface currents flow in a clockwise direction.

True

True or false: In the Northern Hemisphere, the water surface of the open ocean moves 45° to the right of the wind.

True

True or false: Most of Earth's surface wind energy is concentrated in the Trade Winds and Westerlies.

True

True or false: Not all thermohaline circulation is so slow.

True

True or false: The densest water in the world is formed in the Antarctic.

True

True or false: The name of the current that flows from north to south along the west coast of North America is the California current.

True

True or false: The ocean is density stratified.

True

True or false: Thermohaline circulation affects all the ocean's water.

True

True or false: Water masses don't often mix when they meet.

True

True or false: Water moved offshore by Ekman transport is replaced by cold, deep, nutrient-laden water.

True

Countercurrents or undercurrents: Countercurrents that exist beneath surface currents. They can be quite large.

Undercurrents

Surface currents affect what two things?

Weather and climate

What currents are found within gyres?

Western boundary currents and eastern boundary currents

What can cause vertical movement of ocean water?

Wind

What can induce upwelling near coasts?

Wind

Vertical movement induced by wind-driven horizontal movement of water.

Wind induced vertical cirucaltion