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Oceanography--Ocean Circulation
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90
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Undergraduate 3
10/10/2010

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Term
2 types of circulation in the ocean
Definition
wind-driven and thermohaline circulation
Term
wind blowing at the sea surface directly drives
Definition
wind-driven circulation
Term
thermohaline circulation is driven by
Definition
changing the density of water by changing temperature and/or salinity
Term
wind-driven circulation is mostly limited to
Definition
near-surface layer of the ocean
Term
thermohaline circulation is responsible for
Definition
ventilating the global ocean, impact is felt all the way at the bottom
Term
belowe surface layer
Definition
thermohaline dominates
Term
eckman transport moves near surface water to the right
Definition
(90) of the wind direction in the Northern hemisphere
Term
eckman transport moves near surface water to the left
Definition
(90) of the wind direction in the Souther Hemisphere
Term
in eckman layer, wind stress acting on the water particle is
Definition
balanced by coriolis force
Term
if a low atmosphereic pressure system is located over the open ocean, resulting eckman transport moves
Definition
near-surface water AWAY FROM the center of low pressure causing DIVERGENCE
Term
if a high atmospheric pressure system is located over the open ocean, resulting eckman transport moves
Definition
water TOWARD the center of the low pressure causing CONVEGENCE
Term
upwelling will result, bringing
Definition
sub-surface water toward surface
Term
downwelling will result
Definition
pushing down surface water toward subsurface
Term
winds blowing along a coast cuase either upwelling or downwelling depending on the
Definition
wind direction relative to the orientaion of the coast
Term
looking into the downward direction, if the land is located on your LEFT
Definition
the resulting eckman transport moves the warm near-surface water AWAY FROM the coast, cuasing coastal UPWELLING in the N. hemisphere
Term
looking into the downward direction, if the land is located to your RIGHT, the resulting eckman transport moves
Definition
the warm near-surface water TOWARD the coast, causing coastal DOWNWELLING in N. hempisphere
Term
In southern hemisphere, if the land is located to your RIGHT, the resulting eckman transport moves
Definition
the warmer near-surface water AWAY FROM the coast, causing coastal UPWELLING
Term
in the souther hemisphere, if the land is located to your LEFT, the resulting eckan transport moves the
Definition
warmer near surface water TOWARD the coast, causing coastal DOWNWELLING
Term
coast upwelling brings
Definition
colder nutrient-rich sub-surface water closer to the surface where sufficient sunlight is avaliable, brining about higher biological productivity
Term
eckman transport in response to the usual trade winds blowing from east to west near the equator
Definition
moves near-surface water away from the equator in both hemispheres, bringing colder and nutrient-rich sub-surface water closer to sea surface
Term
if the direction of the wind reverses, the resulting eckman transport moves
Definition
near-surface water toward the equator, causing downwelling
Term
often a tongue of cold surface water is found
Definition
in the eastern part of the atlantic and pacific ocean
Term
cold tongue is absent in western part of the asin is due to
Definition
the accumulation of warm near-surface water by the trade wind
the resulting warm surface water is very thick in the western basin
even equitorial upwelling can't bring colder sub-surface water very close to the surface
Term
( geostrophic adjustment) any distrubance in sea level field will undergo an adjustment process until
Definition
geostrophic current is achieved
Term
geostrophic current
Definition
when pressure gradient due to sea level slope is balanced by coloris force
Term
important to know sea level slope because
Definition
one can estimate current speed due to geostrophic current
Term
subtropical gyre
Definition
in subtropics, a subtropical high pressure system in the atmosphere is located
northern half= westerly winds
southern half= easterly trade winds
Term
eckman transport resulting from subtropical gyre wind pattern causes
Definition
convergence below this high pressure system
Term
eckman transport resulting from subtropical gyre wind pattern causes
Definition
convergence below this high pressure system
Term
resulting geosrophic current flows CLOCKWISE in the
Definition
NORTHERN hemisphere
Term
resulting geostrophic current flows COUNTERCLOCKWISE
Definition
in the SOUTHERN hemisphere
Term
eastern boundary currents and western boundary currents are generally
Definition
narrower, swifter
Term
western boundary currents are
Definition
stronger because magnitude of coloris force changes with latitute
Term
Antarctic circumpolar current (ACC)
Definition
steady unimpeded westerly wind blowing north of the Antarctic continent drives ACC which carries the largest transport of any currents
Term
ACC is also a geostrophic current responding to
Definition
the cooling near the antarctic
its deep
Term
water mass
Definition
volume of water with distinct temperature and salinity characteristics
Term
ocean atmosphere interaction at sea surface
Definition
controls thermohaline circulation
Term
tremendous cooling taking place near Antarctic continent produces
Definition
the heaviest water mass in the world, Antarctic Bottom Water
Term
Antarctic Bottom Water (ABW)
Definition
heaviest water mass in the world
mainly in the Weddell Sea and some over the continental self in the Ross Sea
Term
once formed, ABW flows northward following
Definition
the bottom contour
Term
strong winter-time cooling in the Norwegian Sea produces
Definition
North Atlantic Deep Water (NADW) partly due to the fact that surface water in the North Atlantic is relatively salty and when childded it becomes heavy
Term
salty surface water in north atlantic is due to
Definition
strong evaporation in the north atlantic and a salty water flowing out of mediterranean sea
Term
north pacific ocean where no deep water is formed because
Definition
north pacific receives excess precipitation (fresher surface water)
Term
NADW flows
Definition
southward
Term
once meeting ABW coming from the south
Definition
NADW rides over ABW
Term
Antartctic Intermediate Water (AIW)
Definition
north of antarctic continent,
cooling at the sea surface produces AIW which sinks to intermediate depth because it is not heavy enough to reach deep depths
Term
once AIW sinks, it will move
Definition
northward
Term
AIW is characterized by
Definition
higher dissolved oxygen content (formed at sea surface)
Term
Arctic Intermediate Water
Definition
Counterpart of AIW in the northern hemisphere
Term
global thermohaline circulation
Definition
starting from north atlantic
reaches north pacific
Term
takes approximately 100 years for NADW to travel from
Definition
the formation region in the north atlantic to the north pacific
Term
Great ocean conveyor
Definition
return journey of NADW
Term
dating of water masses
Definition
measuring concentrations of man-made chemicals tracers such as freon and radioactive tracers such as tritium
Term
north atlantic is
north pacific is
indian ocean
Definition
saltiest
freshest
somewhere bewteen
Term
average temperature of all ocean water is close to
Definition
3.5 degree celcius
Term
oceanic eddies or rings are
Definition
oceanic counterpart of weather systems in the atmostphere
Term
oceanic eddies are much ______ than atmospheric eddies
Definition
smaller
Term
first systematic large scale field experiment to study turbulent nature of ocean was
Definition
MODE (Mid-Ocean Dynamics Experiemtn) in North Atlantic
Term
often gulf stream becomes unstable and develops
Definition
meanders and subsequently forms rings (or eddies)
Term
rings formed to the north of the gulf stream are called
Definition
warm core rings (contain warm water of sargasso sea)
Term
rings formed to the south of the gulf stream are called
Definition
cold core rings (contain cold water coming from the north of the gulf stream)
Term
eddies play important role in mixing
Definition
different water masses and transfer heat away from the tropics
Term
driving forces for both types of circulation are located at the
Definition
sea surface
Term
coriolis force balances
Definition
wind stress
Term
divergence at the sea surface leads to
Definition
upwelling of colder water
Term
convergence at the sea surface leads to
Definition
downwelling of warm surface water
Term
coastal downwelling
Definition
eckman transport moves water toward the coast
Term
coastal upwelling
Definition
eckman transport moves water away from the coast
Term
how to figure out coastal upwelling/downwelling
Definition
1: identify location
2: identify the direction of eckman transport
3: toward the cost or away from coast
Term
easterly trade winds force
Definition
equatorial upwelling
Term
cold tongue in eastern equatorial pacific contributes signifcantly toward
Definition
global biological productivity
Term
wind blowing at the sea surface creates
Definition
undulations in the sea surface
Term
strong currents such as the gulf stream often are unstable and form
Definition
meanders. some meanders become eddies and rings
Term
because of the presence of the coriolis force it is difficult to mix
Definition
different water masses in the ocean and different air masses in the atmosphere
Term
role of oceanic eddies
Definition
similar to atmospheric eddies
contribute toward poleward heat transport
contribute toward mixing of water masses across fronts
contribute toward global water budget
Term
loop current often forms
Definition
loop current rings which migrates to the western gulf of mexico and eventually decays there
Term
sub surface currents
Definition
subtropical--ocean dominated by subtropical gyre
maintained by subtropical high pressure system and its associated with wind
higher sea level in the middle of a basin
Term
powerful western boundary currents flow along
Definition
the western boundaries of ocean basins in both hemispheres
Term
what currents are found within gyres
Definition
western boundary current
eastern boundary current
Term
western boundary current
Definition
narrow, deep fast currents found at western boundaries of ocean basins
Term
eastern boundary currents
Definition
cold, shallow and broad and boundaries aren't well defined
Term
water mass is always formed at
Definition
sea surface
Term
each water mass has distinct characteristics including
Definition
temperature, salinity and other water properties
Term
ocean is density stratified with the densest water
Definition
at the bottom
Term
5 common water masses
Definition
surface water
central water
intermediate water
deep water
bottom water
Term
deep zone comes into contract with atmosphere in the
Definition
polar region where heavy cold water filling the deep zone is formed
Term
spreading of various water masses can be traced by
Definition
man-made tracers such as tritium and CFCs used a coolants in refrigerators and air conditions
Term
why the pacific ocean is not becoming fresher while the atlantic ocean is not becoming saltier
Definition
large scaled ocean circulation redistributes excess freshwater and salt
ocean circulation moves the salty water from atlantic and eventually to pacific
in return it moves the fresher water from pacific and eventually into atlantic
indian ocean lies in the passage way between these two
Term
in the deepest part of any major ocean basin
Definition
the heaviest water is found (ABW) antarctic bottom water
Term
role of oceanic circulation
Definition
contribute toward global heat budget
contribute toward global freshwater budget
affect global climate
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