Earth Science > Ocean currents and waves > Flashcards

Ocean currents and waves Flashcards

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1
Q

Thermohaline currents

A

caused by density differences / salinity and temperature differences in deep layer
Sink toward equator with high density then
Spread horizontally to even out pressure

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2
Q

current layers

A

surface
Pycnocline
Deep
Cold dense salty sinking water
Sea bottom

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3
Q

pycnocline

A

boundaries between two water layers of different density

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4
Q

surface current

A

winds

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5
Q

Polar water (isothermal, isopycnal)

A

cold and denser than rest.
When it sinks it spreads across bottoms of all oceans- making it deep water now
Deep water and polar water are not seperated by pycnolcine

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6
Q

isohaline

A

when deep water and polar surface water have same salinity
Summer- fresher less salt water

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7
Q

Equator and tropics and subtropics

A

surface waters heated
Pycnocline
Less dense
Salinity decreases
Subtropics- ALOT saltier than polar water
Equator- a little more saltier

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8
Q

mid latitudes - seasonal pycnocline

A

summer- heat and seperate from deep water
Making Pycnocline
Winter- isopycnal depth - surface and deep waters mix

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9
Q

why mixing matters

A

biological productivity
Phytoplankton- seafloor decomposition ->
Pycnocline-> nutrients trapped at depth, risking their population

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10
Q

Depth and travel across Pycnocline

A

changes density and temperature
Density and salinity - more at each Pycnocline going downwards
Halocline= pycnocline for salt
Thermocline= for temperature
Temperature- colder going down, becomes isothermal farthest down, no change

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11
Q

AAIW

A

antartic intermediate water
North of antartica
Goes below antlantic, pacific and Indian
Sits atop all other thermohaline and less dense
Surface currents push water towards each other- water pile- downwelling below pycnocline goes towards deep equator water
Warmer and fresher than water beneath it

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12
Q

deepest densest water- Antartic bottom water

A

antartic bottom water
Antartic circum polar current= Surface current that isolates it from surrounding weather and currents (colder)
Coldest

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13
Q

arctic water

A

surrounded by cont shelves- doesnt enter all oceans
Sink and spread southwards and ride over antartic bottom water
Then toward antartica where surface water gaps exisst and allows it to get upwelled

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14
Q

Mediterranean Sea

A

Intermediate current to Atlantic Ocean
High evaporation adn slaty warm dense water
Isolates this water and piles up, exists than sinks and spreads under Pycnocline
Sits at Atlantic Ocean bathtub

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15
Q

North Atlantic central surface water

A

least dense (Warm temperature)
Hottest
salty

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16
Q

AAIW

A

low density
Fresh adn cold

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17
Q

North Atlantic deep water

A

less fresh than antartic bottom water
more cold

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18
Q

Ekman spiral

A

wind blows on surface
Currents - forward velocity, wind transfers energy, water pushes forward 45 degrees to right or left of wind direction
Not straight with the wind- coriolis effect
Water beneath it even moves it but slighting away from direction above that= spiraling motion
Goes slower and more rotated going down

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19
Q

Ekman transport

A

all current layers summed
90 degrees to right of wind direction in northern hemisphere
All motions of 45 degree separation summed up = net water/ ekman transport

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20
Q

surface objects

A

45 degree angel to wind
Entire packet of water = 90 degree

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21
Q

westerlies and trade winds

A

90 degrees water blows
Trades- left in southern
Westerlies- Right in northern
Water pile domes at center between them

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22
Q

coriolis on dome center

A

water pushed towards center by coriolis affect
Gravity pulls it back out
Earth rotation off enters it
Continents trap motion in a basin

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23
Q

Result of winds and coriolis and gyre

A

water in northern hemi, move in clockwise circle (gyre)
Counter-clockwise in southern hem
2 for Atlantic
2 for pacific
1 for Indian

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24
Q

highest centers for sea surface

A

water moving around gyres
Along western boundary and moves towards poles= western boundary current
Runs eastern boundary towards equator = eastern boundary current
Westward along equator= equatorial current
Eastward along top = transverse current

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25
shapes of domes
tight wind movement on west and east West= speed, force and depth East= wide , slow and shallow
26
Equatorial counter currents
east along equator Between normal ones Small From water buildup Carry water west Moves towards pole or currents carry back to equator
27
antartic circumpolar current - west wind drift
casued by westerly winds from west to east Carries largest volume
28
Northern Atlantic polar currents
mixes surface of northern Atlantic with the Atlantic
29
ocean mixing
poles- easy, no Pycnocline Breaking through when surface areas piles up and down wells to mix Surface water pulled away, upwells deep water to mix upward
30
Surface currents converge
causes water piles Causes AAIW At western equatorial currents converge with land
31
current diverge
North Atlantic deep water rises around antartica, south to zones of convergence Equatorial pacific- leave hole in water. And upwelling
32
california coastal upwelling
winds from south Water pulled away from shoreline (coriolis deflection) Deep water upwells Wind from north- Water pushed up onto beach Downwelling Coastline bends inland- water pulled south where deep water can well up On down current sides
33
seamounts collisions
upwelling on nearby surface Marine life
34
upwells and coastline
Cold and nutrient Marine autotrophs Birds Increases humidity with fog banks and rain Upwelling zones showed underwater seamounts
35
foamlines and Langmuir cells
Strong winds across water for a long time Local limited upwelling Zones collide - local limited downwelling Floating sea foam collect along convergence Mix surface waters
36
pollutants and garbage patches
floating- oil and plastics Collect in still waters Garbage patches- two zones of convergence in center of North Pacific gyre
37
El niño oscillation
sways from nino to Nina
38
normal
trade- across equatorial from high pressure east to low pressure to west (equatorial current) This warm water dome move through world’s gyres Some go eastward (counter current) Is weak and small in comparison to equatorial currents Result of all this surface water being removed from eastern side where there isn’t a dome of warm water -> biggest upwelling nutrient zone
39
la nina
trade wind pressures increase Land dry in east Wind greater in west Upwelling greater
40
El Niño
Pressure reverses the trade winds from westward to eastward Intensifying countercurrent Moisturizing deserts in eastern pacific Increased waves and erosion Upwelling and nutrients stop Western pacific rainforests lose water
41
oscilaltion (ENSO)
eastern equatorial pacific Nino- warm surface waters Nina- colder than normal (more upwelling) Very frequently 1-7 years
42
California and ENSO
nino- warmer surface water, upwelling stops Weak trade winds - rainstorms Warm water along equator that changes fish populations- weakening predators
43
Waves
transferred energy No net motion of water Returns to original position
44
Chop sea waves
made locally Sea storm Winter storm
45
swells
from far off storms Regular ordered sets of wave trains Have same height, length and period
46
tides
most common Differences in gravitational forces (sun and moon)
47
wave formation
move along boundaries Restoring and generating forces
48
generating and restoring force
Pushes water across air boundary (up) Along layers Pycnocline waves- affect submarines Pulls it back for balance Surface tension of hydrogen bonded skin
49
Generating force stops
water stills
50
capillary waves
surface tension of water restores the water shape like gelatin bounces lightly
51
Gravity waves (restoring)
when generating force breaks the hydrogen bonds Gravity restores the water to its original shape
52
wind
increased intensity changes it from capillary to gravity Capillary, chop, swell, seiche
53
types of generative forces
wind, splash displacement, uneven gravitational forces
54
Seiche
can be created by landslides, earthquakes, splash events But mostly tsunamis are these things
55
tallest waves
swell Tides
56
Longest wave lasting
tide (24 hours) Tsunamis
57
Amplitude
vertical distance from its still water line (equilibrium surface)
58
Crest and trough
high and low equally distanced from amplitude
59
wave height
crest and trough distance
60
wave length
crest to crest Trough to trough Spot to spot
61
wave base
under wave depth where there’s no motion felt Descending the distance of the wavelength from the still water line Energy just stops after that point Moving energy, not moving water Energy extends downwards, but the waves have a limit, only to oscillate balancing enegry, not penetrate entirely Is half the wavelength
62
standing wave - seiches
limited space Small lagoons and bays Sloshes over basin and floods areas
63
tidal seiche -
largest standing wave Gravitational differences Sloshing back and forth
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tsunamis and wind generated= progressive waves
Move away from original location Generating force goes away after time Transverse- earthquakes, sideways, along land surface Compressional longitudinal waves- earthquake, sound, compress and expand air, as wave travel from source to place
65
Orbits
move eveyrthing in it in Same motion
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Wave period/ duration
seconds per wavelength
67
Wave speed
distance = wavelength over period
68
deep water waves
move through water deeper onto their wave base
69
shallow water waves
erosion, frictional slow at base of wave Wavelengths decrease Heightens Circular orbit to olliptical Same period
70
transitions between being shallow or deep wave
depends on how close the seafloor is Wavelength As long as they feel the bottom or not
71
Biggest waves
strongest winds Longest periods Longest fetch (area with no path blockages) Antartica southern ocean Strong westerlies Infinite fetch
72
Wave interference
Tall waves from different storm systems interfere with each other Constructive- Crest combination adds upon each other Destructive- crest to trough- when they meet out of phase - wave gets smaller
73
Rogue wave- episodic
constructive waves Most damage
74
Wave differentiation
Different storm systems Same storm, waves reflected and collide Waves bend and collide
75
Refraction
waves collide witch beaches Waves that feel the bottom first slow down Deeper water wave speeds forward \ Causes bend inward towrads headland (beach) or anything rocky Eroding anythything there (energy centered)= refraction Diffraction- waves go outwards, gentle
76
reflection
bounces back off something
77
steep waves
they break Wave height divided by wave length Must be 7 times longer than height 1/7th
78
tsunamis- splash waves
landlside under water Vertical displacement of seafloor by earthquake - subduction zones super flat
79
Pacific Ocean tsunamis
crescent city Santa Cruz
80
Trough arrives first in tsunami
removes water from beach
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2nd or 3rd crest hits
highest amplitude
82
Under tow
orbital motion of breaking waves
83
Rip currents
Water piles up along shore Moves toward each other and back to ocean Moves off beach and toward ocean Forces through oncoming waves
84
cusp
thick sand where waves deflect left and right
85
longshore current
water and sand pushed in opposite from which they come
86
Tidal datum
the mean lower low water MLLW Average height of lowest low waters in a year
87
troughs
2 in one day One is higher- higher low water low tide One is lower- lower low water low tide
88
tidal period
12 hours and 25 minutes 2 waves- eveyr 24 hours and 50minutes
89
Tidal range
height Vertical distance from crest and trough When they vary- from highest crest to lowest trough
90
Slackwater
not rising or falling
91
then flood current
rises slowly Then super fast- flood current Then high tide slackwater
92
Then ebb current
goes away from coastline super fast Then slackwater at low tide Another flood current- then high tide slackwater
93
Semidiurnal mixed pattern
2 flood currents 2 ebb current Water levels are different
94
Diurnal pattern
1 high 1 low 24 hours 50 Highest range
95
semidiurnal pattern
same but instead fo variation, the water levels are the same
96
2 week patterns
neap tides and spring tides Every 2 week Neap - highest lows, lowest highs Spring- highest highs, lowest lows Small tidal range
97
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