Oceanography-Chapter 09
The ____________ Current is the shallow eastern boundary current of the North Atlantic.
Canary
____________ ____________ currents have diffuse boundaries and move cold water equatorward.
Eastern boundary
____________ ____________, caused by winds from the north, moves water offshore, allowing coastal upwelling to replace surface water along the west coast shore in the Northern Hemisphere.
Ekman transport
Downwelling can have direct effects on the climate of an adjacent coast.
False
During major ENSO events, sea level rises in the western Pacific and water temperatures also increase.
False
Langmuir circulation consists of slowly twisting cells of windows, or convergences where seaweed, debris, and foam accumulate, that operates in the surface layer, as well as below the pycnocline.
False
Surface currents flow vertically in the uppermost 400 meters of the water column.
False
The Ekman spiral is similar to an eddy in that the water spirals downward like a whirlpool.
False
The Pacific's Equatorial Currents are driven eastward by westerly winds and flow faster than the westward flowing currents driven by the trades.
False
Western boundary currents move cold water poleward in each of the gyres.
False
Who was the first to record the observation of currents?
Pytheas
____________ ____________ are wind-driven movements of water at or near the ocean's surface.
Surface currents
____________ ____________ transport the North Equatorial Current and South Equatorial Current in the Atlantic and Pacific westward.
Trade winds
Countercurrents are also known as undercurrents.
True
During a non-El Niño year, the air and surface water flow westward to the western Pacific, the thermocline rises, and upwelling of cold water occurs along the west coast of Central and South America.
True
Gyres tend to collect seaweed and trash as their centers.
True
Sir John Murray observed that the temperature of the ocean's surface water was almost always higher than the temperature of deep water.
True
Surface currents distribute tropical heat worldwide. The winters in Scotland, Ireland, and England are relatively mild due to the energy transported by the North Atlantic Current and the Gulf Stream.
True
The North Atlantic Intermediate Water and the Antarctic Intermediate Water are both produced by caballing.
True
The westward intensification is driven by the Coriolis effect.
True
Recent research suggests that warm- and cold-core eddies may be responsible for slowly moving abyssal storms, which leave ripple marks in deep sediments.
True
The ____________ ____________ ____________ is the greatest of all ocean currents, and flows eastward driven by westerly winds.
West Wind Drift; Antarctic Circumpolar Current
The process of ____________ occurs when two masses of water merge and their combined density is greater than either of their separate densities.
caballing
Gyres in balance between the pressure gradient and the Coriolis effect are called ____________ gyres.
geostrophic
The Coriolis effect causes gyres to flow to the ____________ in the Northern Hemisphere.
right
The movement of water due to differences in density is ____________ ____________.
thermohaline circulation
The ____________ currents flow east to west and west to east, linking the eastern and western boundary currents.
transverse
How long does an ENSO event typically last?
1 year
How much of the water in the world ocean is involved in surface currents?
10%
What is the residence time of most deep waters?
200 to 300 years
What describes the theoretical direction of Ekman transport in the Southern Hemisphere?
90° to the left of wind direction
What water mass is the densest in the world ocean?
Antarctic Bottom Water
An eastern boundary current
Benguela Current
The boundary between which two water masses in tropical latitudes is the most pronounced and abrupt?
Central water and intermediate water
Which is an example of coastal upwelling affecting weather onshore?
Cold water is brought to the surface that chills the air above, inducing cool, wet weather.
An undercurrent
Cromwell Current
_____ currents flow equatorward and are shallow and broad.
Eastern boundary
The "hill" of water that occurs as a result of westward intensification due to the Coriolis effect is formed by _____.
Ekman transport
What is true about the Coriolis effect?
It is absent at the equator.
A western boundary current
Kuroshio Current
Shallow wind-driven helical vortices are produced by ____________ ____________ with windows of convergences where seaweed accumulates.
Langmuir circulation
What is true of density, salinity, and temperature?
Many combinations of temperature and salinity can yield the same density.
What water mass is the most saline in the world ocean?
Mediterranean Deep Water
Equatorial upwelling occurs worldwide, but where is it most pronounced?
Pacific Ocean
Current that slows during ENSO events
Peru Current
Equatorial upwelling occurs in what current?
South Equatorial Current
The change in atmospheric pressure and wind direction that occurs in the Pacific Ocean every 3 to 8 years is known as the ____________ ____________.
Southern Oscillation
What changes are caused by the Southern Oscillation in the Pacific Ocean?
Trade winds blow from west to east.
What can be caused by ENSO events in the eastern Pacific?
Upwelled water is nutrient-depleted, causing loss of productivity.
Wind-induced vertical circulation is also known as ____.
Upwelling/downwelling
What is the largest current?
West Wind Drift
A transverse current
West Wind Drift
The centers of gyres tend to be ____.
calm and support relatively little life
Wind blowing from the south along a Northern Hemisphere west coast for a prolonged period can result in ____________, producing areas that are often low in nutrients and have low biological productivity.
downwelling
What current is associated with upwelling?
eastern boundary currents
The flow of water around the periphery of an ocean basin driven by winds and the Coriolis effect is called a(n) ____.
gyre
Langmuir circulation occurs only ____.
in the top 20 meters of water
The two gyres in the North and South Pacific (and in the North and South Atlantic) converge at the ____________ equator.
meteorological
The transport of heat and energy by surface currents throughout the ocean can have influences on climate and weather. Where does the greatest amount of heat transfer by surface currents occur?
mid-latitudes
Which currents are the slow, deep currents that affect seawater beneath the pycnocline?
thermohaline
The trade winds and westerlies drive what geostrophic currents?
transverse currents
The fastest and deepest geostrophic currents are ____.
western boundary currents
The Gulf Stream is the largest of what type of current?
western boundary currents
What currents carry the highest volume of water?
western boundary currents
Surface currents are driven mainly by ____.
wind friction
