exam4 Flashcards
western boundary currents better defined and flow faster in comparison to eastern boundary currents due to…
Western Intensification
2 reasons why western boundary currents flow faster are
1- Water that is moved westward across ocean by easterly trade winds piles up against continents then must rapidly move northward. In contrast westerlies do not converge so water spreads out before hit contintental boundaries
2 - EARTHS ROTATION - Moves hill of water westward - water must squeeze along western edge of hill
what is el nino
warm water moves into eastern pacific ocean
what is la nina
very cold water moves into eastern pacific ocean
what are the possible causes of enso
1982 reuption of volcano in mexico, El Chicon
EPR heats water
Changes in sea ice off of antartica
Dont know…
Normal conditions of El Nino?
Trade winds, east to west
High- P over East. Pacific, Low-Power Western Pacific
Trade winds move warm water westward along equator
PERU = UPWELL
Cold water east pacific, warm water in west pacific
ENSO
Reversed Conditions of El Nino?
OPPOSITE
High P in West Pacific, Low P east pacific
Trade winds weaken, possibly reverse
WARM WATER INTO EAST PACIFIC
review page 151
page 151
wind produces what kind of horizontal water circulation?
horizontal water circulation and causes vertical circulation
what does upwelling do
bring cold deep nutrient rich water to surface
what are the 2 areas of upwelling
coastal and equatorial
what is downward water movement
downwelling
what is equatorial upwelling
when water mves on either side of geographic equator deflected slightly towards poles by eckman transport. then replaced by deeper colder nutrient rich water
where does equatorial upwelling occur
in westward flowing equatorial surface currents
what are abundant in equatorial pacific
radiolaria
what is coastal upwelling
wind blowing parallel to shore or offshore
When does coastal upwelling occur
deep water replaces coastal water
upwelling important forrrr
peru
what is downwelling
water driven toward coastline by wins
downwelling has…
no direct effect on climate or biological activity along coast
review page 153
review page 153
what are thermohaline circulation
horizontal & vertical currents below pycnocline
deep circulation in thermohaline circulation is driven by wind energy?
nah density differences
what is the density stratification of oceans?
high density near bottom
low density at surface
where is density stratification strongest?
at tropical temperate latitudes
ABW =
Antartic Bottom Water
the most distinctive deep water mass
charaacteristics of ABW
Temp - -0.5
Density - 1.0279 gm/cc
Highest density of world’s oceans
Very mobile
why does ABw form
seawater freezes off coast of antartica, wedell sea
what is the deep circulation in the thermohaline circulation driven by
differences in density
is the entire ocean undergoing a slow thermohaline circulation
ya
explain the formation and downwelling of ABW
water sinks rapdily in small area in cold ocean
rises slowly across large area in temperate & tropical zones
returns slowly poleward to repeat cycle
T or F
Forams are smart critters they have figured out that ekman transport is responsible for equatorial upwelling in the tropical pacific ocean. The upwelling brings cold, nutrient-rich water to the surface for their dining pleasure. This is why they have moved there
True
What is the following considered, Upwelling or downwelling?
West coast of the chile where surface water moves onshore because water turns to the left as a southerly wind causes Ekman transport to occur
Upwelling
Average conditions in the w pacific are warm water and low pressure
False
One possible cause of the 82 - 83 enso was the eruption of el chichon volcano
ya
average conditions in the east pacific is a strong downwelling along the coast of peru
false
what is classifications of waves based on
1 - disturbing force creates wave
2 - restoring force flattens / destroys wave
3 - lambda (wavelength)
AND DISTURBING FORCE
what is disturbing force
energy that causes ocean waves to form
what are some examples of disturbing forces
wind storm surge eqs, volcanic eruptions gravitational forces earths rotation
waves moving thru water deeper than lambda/2 = what kind of waves
Circular orbits
Deep water wave
waves moving thru near-shore water where depth < lambda/20
elliptical orbits
Shallow water waves
characteristics of common wind waves
deep water
period < 20 seconds
lambda < 600 meters
speed < 112 kph
characteristics of shallow water waves
tsunami
period < 20 minutes
lambda = 100 - 200 km
speed ~ 850 kph
what are 3 factors that affect growth of wind waves
wind strength
wind duration
fetch
what is fetch
uninterrupted stance over which wind moves without significant change in direction
what is the ratio of wave height to wavelength
1:7
wave separation =
dispersion
look at drawing of swell
its on page 164 smooth undulations of ocean surface
look at the drawing of dispersion
to left many different lambdas
and to the right there is a single lambda
explain dispersion
waves from storm sort themselves into groups with similar wave length and velocity
they disperse
then they swell
what is interference
a usual situation in open ocean in which multiple sets of wave trains moving all dirctions from different sotrms interact with each other
interaction =???
interference
constructive interference occurs btn waves of different lambda’s of
big waves
destructive waves interference btn waves of different lambda’s of
no or little waves
review constructive interference pic
page 166
simliar large waves for both sets
the resulting swell is largest
review the destructive interference pic
page 166
swells mirror each other for both sets
the resulting swell is nothing
wave story time
Storms bring wind/ energy
Brings many diff wave lenghts
dispersion occurs
deep water waves swell and theres a single wave length
wave train happens
approach the coast
bottom of the wave touches the bottom = shallow
friction with bottom of ocean bottom of wave slows
crest continues ahead, lambda shortens
violates 1:7 ratio and wave breaks
energy goes into surf zone ; erode the coast or transport sediment
what is wave diffraction
propagation of a wave around obstacle, wave changes direction due to obstacle not velocity
what is wave refraction
waves approach shore @ angle than head on
wave bends or refracts due to change in velocity
slowing and bending of waves in shallow water
longer lambda waves more faster or slower
moves faster
