Elementary Oceanography Chapter 7
Indian Ocean currents that are generated by seasonal changes in weather patterns are the __________ and __________ Currents.
Somali/Southwest Monsoon
The loss of heat from the ocean surface, resulting in a lowered temperature, causes ocean water to become __________.
denser
Deep ocean currents are driven primarily by ________ .
density differences
Converging surface waters are areas of ________ and ________ productivity.
downwelling; low
Equatorial currents that are part of the subtropical gyres flow ___. Equatorial counter currents between the gyres flow ___ .
east to west; west to east
A large system of rotating ocean currents, usually driven by the major wind belts, is called a(n) __________.
gyre
Which of the following currents is responsible for Peru becoming the largest producer of fish, from the sea, in the world?
humboldt current
Which process causes downwelling off the coast of Antarctica?
ice formation
Deep-water currents move ________ volumes of water and are much ________ than surface currents.
larger; slower
In the figure above, which of the labeled currents are eastern boundary currents?
- C - N - H
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.
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
One of the world's most powerful currents, located off the east coast of the United States, is the __________.
Gulf Stream
The current in the northwestern part of the North Atlantic Subtropical Gyre that transports warm water toward the North Atlantic is called the __________.
Gulf Stream
Which ocean current is the strongest and fastest ocean current in the world?
Gulf stream
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
The El Niño Southern Oscillation can best be described as:
the relationship between sea surface temperature and changing atmospheric pressure
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
The Gulf Stream is an example of which of the following types of currents?
western boundary current
The Kuroshio (Japan) Current is an example of which of the following types of currents?
western boundary current
Which subtropical boundary current is faster, narrower and deeper than its counterparts?
western boundary current
Warm core rings and cold core rings are associated with __________.
western boundary currents
What is the Southern Oscillation?
the swapping of high and low pressure zones in the South Pacific under El Niño conditions
Under which conditions are droughts and wildfires common in Australia?
under El Niño conditions
Surface ocean currents are driven primarily by ________ and modified by ________.
wind; the Coriolis effect and land
In the figure above, which of the labeled currents are warm water currents?
- B - E - F
Of the following surface currents, which one(s) transport large volumes of warm water to higher latitudes? Choose all that apply.
- Brazil Current - Kuroshio Current - the Gulf Stream
Of the following locations, where would upwelling be expected to occur? Choose all that apply.
- In areas of diverging surface currents - Where seamounts or tablemounts are present - Where there is a sharp bend in a coastline
In the figure above, which of the labeled currents are shallow, weak, and slow currents?
- N - H
The West Wind Drift is a part of which of the following subtropical gyres? Choose all that apply.
- South Pacific Subtropical Gyre - South Atlantic Subtropical Gyre - Indian Ocean Subtropical Gyre
Of the following gyres, which one(s) flow in a counterclockwise direction? Choose all that apply.
- South Pacific Subtropical Gyre - South Atlantic Subtropical Gyre - Indian Ocean Subtropical Gyre - Northern Hemisphere Subpolar Gyres
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.
What factor(s) drive(s) Ekman transport?
- Wind - Coriolis effect
Surface ocean currents ___. CHOOSE ALL THAT APPLY.
- are driven by winds - form large rotating gyres in the major ocean basins - are influenced by Coriolis effect
Which force(s) drive(s) water circulation in the deep ocean? Choose all that apply.
- differences in water density - differences in water temperature - differences in water salinity
Why does the west coast of South Africa have high biological productivity? Choose all that apply.
- high concentrations of nutrients in the surface water - lots of coastal upwelling
Which of the following conditions would be expected for the eastern Pacific during an El Niño event? Choose all that apply.
- sea level rise - floods - reversed Walker circulation - a deeper thermocline
Which of the following conditions would you expect to find off the coast of Peru under normal, or neutral, El Niño-Southern Oscillation (ENSO) conditions? Choose all that apply.
- shallow thermocline - abundant anchovies - dry, clear conditions
Which of the following conditions would be expected for the western Pacific during an El Niño event? Choose all that apply.
- wildfires - weaker trade winds - high atmospheric pressure
As shown in NASA satellite data, in what years were the two most recent strong El Niño events?
1997-1998 and 2015
In which direction does the surface current move in relation to the wind in the Southern Hemisphere?
45 degrees to the left
To produce a surface current of 1.6 knots in the open ocean, a steady wind of _____ knots would be required.
80
Which of the following is the only current that completely circumscribes Earth?
Antarctic Circumpolar
The arrangement of water masses in the southern Atlantic Ocean from the surface to the bottom is:
Atlantic Intermediate Water, North Atlantic Deep Water, Antarctic Bottom Water
Which of the following is a western boundary current?
Brazil Current
When a meander from the Gulf Stream pinches off into the warm water south of the current, the eddy is called a __________.
Cold core eddy or ring
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.
In the figure above, which shows a cross section of the Atlantic Ocean extending from Greenland (north) to Antarctica (south). Which labeled layer represents a cold-water mass mixing with warmer water to create a water mass with intermediate density?
E
The false-color map of sea surface temperatures shown below is an example of which of the following features?
El Nino conditions
Which current that flows along the equator is driven by a difference in sea level caused by ocean circulation patterns?
Equatorial Countercurrent in the Pacific Ocean
Which of the following methods are used to measure deep ocean currents directly?
Free-drifting Argo floats
In the figure above, which shows a cross section of the Atlantic Ocean extending from Greenland (north) to Antarctica (south). Which labeled layer has the highest density?
G
Which of the following two factors cause geostrophic circulation within a gyre?
Gravity and the Coriolis Effect
During La Niña, what happens to the Pacific Warm Pool?
It gets pushed farther west.
Why is Antarctic Bottom Water so dense?
It is cold and salty.
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.
Based on the graph, which of the following has the highest salinity?
Mediterranean Intermediate Water (MIW)
The Gulf Stream transports warm water into the __________.
North Atlantic
Based on the graph, which of the following has the highest temperature?
North Atlantic Central Surface Water (NACSW)
Based on the graph, which of the following has the lowest density?
North Atlantic Central Surface Water (NACSW)
A deep and powerful southward subsurface current that flows under the Gulf Stream in the North Atlantic is the __________.
North Atlantic Deep Water
Which of the following methods are used to measure ocean surface currents indirectly?
Pressure gradients
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.
About what percent of the wind's energy is transferred to the ocean surface?
Two
The largest of the great ocean surface currents is the __________.
West Wind Drift
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.
What common household item is used in this video to demonstrate the Ekman spiral?
a deck of playing cards
The thermocline is _________________.
a steep temperature gradient in the ocean that separates deeper cold water from warmer upper water
To what depth in the ocean does the Ekman spiral extend?
about 100 meters (330 feet)
Warm ocean currents ___.
are warmer than the surrounding water
Compared to western boundary currents, eastern boundary currents are:
broad and slow
Which of the following currents contributes to the South Western United States being arid?
california current
When a meander from the Gulf Stream pinches off and isolates a body of water within the North Atlantic gyre, the body of water is called a:
cold core ring
An increase in seawater density can be caused by a ________ in temperature or a/an ________ in salinity.
decrease; increase
The California Current is an example of which of the following types of currents?
eastern boundary current
The Peru (Humboldt) Current is an example of which of the following types of currents?
eastern boundary current
Which direction do ocean currents in the South Pacific move under El Niño conditions?
eastward
Ocean frontal systems that spin off from currents such as the Gulf Stream, akin to atmospheric storms, are known as __________.
eddies
Coastal winds can cause upwelling or downwelling due to which of the following?
ekman transport
The observation that ships and icebergs in the southern hemisphere float to the left of the wind direction is an example of which of the following?
ekman transport
The North Equatorial Current is an example of which of the following types of currents?
equatorial current
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 circulation brings oxygen from the surface to the deep ocean because of:
greater dissolution of oxygen in colder water than warmer water
Which of the following currents contributes to the South Eastern United States being humid?
gulf stream
Fluctuations in the flow of the Gulf Stream current result in curving loops of water known as __________.
meanders
The Sargasso Sea is the water that circulates around the rotation center of the ________ gyre.
north atlantic
The North Atlantic Current is an example of which of the following types of currents?
northern boundary current
The North Pacific Current is an example of which of the following types of currents?
northern boundary current
Ocean surface currents transfer about ________ of the total amount of heat from the tropics to the poles.
one-third
Which ocean condition(s) would result in downwelling?
onshore Ekman transport
The subtropical gyres ___.
play a large role in climate
Warm currents flowing ________ on the ________ sides of continents produce warm, humid conditions.
poleward; eastern
Deep ocean currents ___.
result from changes in water density (due to temperature and salt content)
In the Northern Hemisphere, the Ekman spiral moves layers of water to the _____ of the wind direction and Ekman transport (the overall direction of water movement) is to the _____.
right; right
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
Between summer and winter, which of the following currents reverses its flow direction?
somali current
Sources of deep water in the ocean include all of the following except:
subtropical convergences
Which of the following statements is true of surface ocean currents?
surface currents form circular patterns in the major ocean basins called 'gyres'
Thermohaline circulation in the ocean is driven primarily by differences in __________ and __________ among water masses.
temperature; salinity
In comparison to wind energy, ocean currents can generate more clean, renewable energy because __________.
the density of water is greater than that of air
The Ekman spiral is caused by:
the wind and the Coriolis effect.
Deep ocean current movement is also known as __________.
thermohaline flow
In the southern hemisphere, the direction of Ekman transport is always:
to the left of the wind direction
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
Cold currents flowing ________ on the ________ sides of continents produce arid conditions.
toward the equator; western
Equatorial currents are driven by the:
trade winds
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