Download Oceanography Final Exam 6-10

Oceanography Notes
Midterm Corrections
o Lines of latitude measure north-south with respect to the equator
o Old, cold oceanic lithosphere more dense than:
 underlying warm aesthenosphere
 continental lithosphere
 younger oceanic lithosphere
o Continental Margin order: Shelf, Slope, Rise
o Oceanic crust floats lower on mantle because it is denser
o Free oxygen produced by photosynthesis
o Evaporation is a warming process
Chapter 6
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atmosphere and ocean interdependent
surface currents correlate with wind belts
interchangeable results b/w ocean/atmos
radiant energy from sun responsible for motion in atmos and ocean
ecliptic: the plane traced by earth’s orbit
earth tilts at 23.5%
earth axis is always pointing in same direction, toward Polaris [N Star]
 -causes seasons
vernal equinox: occur about 21 March, sun directly overhead along equator.
 -during this, all placed on earth experience same length night and day
 -N hemis, this is spring
summer solstice: june 21. sun at most northerly point in sky, directly above tropic
of cancer
 -at noon this day, sun seems to pause in sky.
Tropic of cancer: 23.5 degrees N lat
Autumnal equinox: sept 23. sun directly overhead along eq again.
 -also known as fall equinox in N hemis.
winter solstice: dec 22. directly overhead at tropic of Capricorn
 -S hemis seasons reversed, this is when S hemis most directly facing
sun. This is beginning of S hemis summer.
tropic of Capricorn: 23.5 degrees S lat
declination: angular distance from equatorial plane
 -sun’s declination varies b/w 23.5 degrees N and S lats on yearly cycle
tropics: region b/w Capricorn and Cancer
 -receive greater annual radiation that poles
N hemis: longest day-summer solstice, shortest day-winter solstice
Exceptions to daily cycles of light and dark:
 Arctic circle: 66.5 degrees N lat
 Antarctic Circle: 66.5 degrees S lat
 -during N hemis winter, area N of arctic circle experiences 6 months
darkness, area S of Antarctic circle experiences 6 months daylight
 half a year later, this situation reversed
sunlight strikes low lat at high angle; radiation concentrated in small area
sunlight strikes high lat at low angle; same amount of radiation spread over larger
area
atmosphere absorbs radiation, so less radiation at high lat, b/c passes through
more atmosphere
Albedo: percentage of incident radiation that is reflected back to space.
 -avg albedo of earth’s surface: 30%
 -ice has higher albedo than soil or vegetation so more radiation reflected
back into space at high lats
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-angle at which sunlight strikes ocean surface determines how much absorbed
and how much reflected
 -directly: 2% reflected
 -5 degree above horizon: 40% reflected
 -so, ocean reflects more radiation at high lats
 Elevation of sun above atmosphere:
90
60
30
15
5
 Reflected radiation [%]
2
3
6
20
40
 absorbed radiation [%]
98
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94
80
60
amount of radiation varies annually due to Earth’s seasons
amount of radiation varies daily b/c of day and night due to rotation
temperature difference b/w equatorial zone and poles remains the same, b/c
excess heat transferred from equatorial zone to poles [circulation atmos and
ocean]
Composition of dry air:
 Nitrogen 78.1%
 Oxygen 20.9%
 Argon .9%
 CO2 .037%
 Other trace
troposphere: surface-12km[7m]. all weather produced here. much atmospheric
mixing.
 -temperature is cooler with altitude in troposphere
air has density
higher temperature, lower density [for air]
 -warm air rises, cool air falls
convection cell: rising and sinking air moving in circular fashion
warm air holds more water vapor because it has more contact with water vapor
due to quick moving particles.
warm air moist, cool air dry
 -warm breezy air-evaporation
more water vapor in air=decreased density
atmospheric pressure= 1.o atmosphere [14.7lbs/sq inch] at sea lvl
 -decreases with increasing altitude [pressure depends on weight of air
column above]
column of cool dense air: high pressure at surface; leads to sinking air
 -movement toward surface and compression
column of warm, less dense air; low pressure at surface; leads to rising air
 -movement away from the surface and expansion
air always moves from high to low pressure areas
principles that drive physical movement of air remain same whether earth is
spinning or not
Coriolis Effect: changes the intended path of a moving body. Gaspard Hustave
de Coriolis [1835].
 does not influence the body’s speed [not a force]
 this effect causes moving objects on earth to follow curved paths
 N hemis; object goes right
 S hemis; object goes left
 the directions right and left are the viewer’s perspective looking I the
direction in which the object is traveling
 -ball thrown b/w two people will curve slightly to right in N hemis
from the thrower’s point of view
 -greater effect on objects going long-distance, especially N-S
 result of earth’s eastward rotation
 the difference in the speed of Earth’s rotation at difference lats causes
this effect
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maximized at poles and zero at the equator.
merry-go-round; fall off tangent to circle
Coriolis effect perspective; the one looking in direction object is moving
distance that a point must travel in a day shorter with increasing lat
1600 km/hr earth sping rate [0 at poles]
this change in velocity w/ lat is true cause of Coriolis effect
1400km/hr at 30 degrees lat N and S
missile launched straight at target will curve right [to the eye], but really,
that target [point on earth] has a faster or slower velocity that the launch
point
 friction not taken into account; has a great effect
 rate of change of rotational velocity [per degree of lat] increases as the
pole is approached from equator
 [from 200km/hr b/w eq and 30 deg N lat to 600km/hr b/w 30 deg
N lat and 60 deg N lat]
 60 deg N lat- N pole -> 800km/hr difference
 max Coriolis effect at poles, no Coriolis effect at equator
 Coriolis effect summary:
 -caused by earth rotation and resulting decrease in velocity with
increased latitude
 -influences all moving objects, esp those moving over large
distances
 -changes only direction, not speed
 -deflection to the right in N hemis, left in S hemis
 -O at equator; increases with increasing lat; strongest at poles.
Hadley Cells: George Hadley [1658-1768] circulation cells resulting from dry air
mass at equatorial zone traveling N or S of equator at 30 deg lat becoming dense
enough to sink and complete the loop
Ferrel cell: 30deg-60deg lat. William Ferrel [1817-1891]. Invented 3-cell [er hemis
model. Cell moves coinciding with adjacent cells.
Polar cells: 60deg-90deg lat.
subtropical highs: high rpessure cones caused by descending air at 30deg N and
S lat.
polar highs: high pressure regions caused by descending air at poles
 -both areas: warm under own weight; dry, clear, fair conditions. Not
necessarily warm
equatorial low: rising air causing a band of low pressure at the equator
subpolar low: rising air causing a band of low pressure at 60 deg lat.
 -both areas: cloudy with much precipitation, because rising air cools and
cannot hold its water vapor
trade winds: massed of air moving from subtropical high pressure belts to
equatorial low pressure belts
 -steady winds named from “to blow trade” [to blow in regular course]
 -if earth did not rotate, trade winds blow NS
 N hemis; northeast trade winds: curve to right; from NE to SW
 S hemis; southeast trade winds: curve to left; from SE to NE
 -the coriolis effect curves these winds
prevailing westerly wind belts: some of descdending air in subtrops moves along
surface to highest lat
 -SW to NE in N hemis; NW to SE in S hemis
polar easterly wind belts: air moving away from high pressure at poles
 -Coriolis effect at poles strongly deflects winds
 -blow from: NE in N hemis, SE in S hemis.
When polar easterlies collide with prevailing westerlies at subpolar low pressure
belts [60 deg lat], the warmer, less dense air of westerlies rises above.
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doldrums: boundary between trade belts. Lack of winds here.
Intertropical Convergence Zone [ITCZ]: doldrums. Between where trade winds
converge.
Horse latitudes: boundary between prevailing westerlies and trade winds [30 deg
lat]
 -high pressure, clear, dry, fair conditions
 -air is sinking and surface winds are light and variable [not much rain]
polar front: boundary between westerlies and easterlies [60 deg lat]
 -cloudy, much precipitation. Battelground for different air masses
poles are cold deserts [not much precipitation]
Ferrel 3-cell idea is only general. Other factors:
 1] tilt of earth’s rotational axis, producing seasons
 2] low heat capacity of continental rock: colder winter, hotter summer
than over oceans
 3] Uneven distribution of land, particularly affecting N hemis patterns
during winter on continent: atmospheric high pressure, summer: low pressure.
such seasonal atmospheric pressure over Asia causes Monsoon Winds.
Christopher Columbus: Italian navigator. Toscanelli: astronomer
 -reached canary islands Aug 3, 1942
 -called West Indies inhabitants “Indians” because he thought they were
near India
 -1498; South America 1502; Central America
Chapter 6 Lecture
Solar energy creates winds
Example of interactions: El Nino, Greenhouse Effect
Theory: Earth tilt due to Mar’s affect.
35degN-35degS->heat gained
Other lats, heat lost
Heat gained moves to poles
troposphere: 60degC-50degC at min temp
Topopause-Stratosphere-Ozone layer-Mesosphere
dry air and cool air sink <-more dense
moist air and warm air rise<-less dense
-moist air less dense than dry air because water has less mass than N2+O2
high pressure->air coming down; low pressure->air rising
deserts have cool/dry air coming down
cool dense air, higher surface pressure
Chapter 6 cont…
o weather: conditions in atmosphere at given time and place
o climate: long-term average of weather
o cyclonic flow: CCW flow of air around low pressure cells as a result of Coriolis
effect on air moving from high to low pressure curving it to the right [N hemis]
o anticyclonic flow: air leaving high pressure region and curves right, establishes
CW flow of air around high pressure cells [N hemis]
o low pressure->clouds high pressure->sun
o winter high pressure cells replaced by summer low pressure over continents, so
continental wind patterns often reverse themselves seasonally.
o land breeze: cool air sinking, blowing over ocean in early morning hours.
 -due to cool sinking air over continents at night as a results of continents
having low heat capacity
o sea breeze: warm air rising, blowing cool air from ocean over continent in
afternoon.
 -due to warm air rising over/above continents during day as a result of
continental low heat capacity.
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Region
0-5
5-30
30-60
60
60-90
Poles
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Wind Belts and Boundaries:
Name
Pressure
Doldrums
L
Characteristics
Light variable wind. Cloudy/Precip.
Hurricanes breed here
Trade Winds
Strong, steady winds generally from E
Horse Latitudes
H
Light, variable wind. Dry, clear, fair. Little
precip. Major deserts here
Prevailing W
Winds generally from W. Brings USinfluencing storms
Polar Front
L
Variable wind. Stormy/cloudy year-round
Polar E
Cold, dry winds generally form E
Polar High
H
Variable winds. Clear, dry, fair, cold
Pressure
temp, min precip. Cold deserts here.
Very high and very low lats, little daily and minor seasonal change in weather
midlatitudes: where storms are common
storms: atmosphere disturbances: strong wind, precip, thunder/lightning
air masses: large volumes of air: definite area of origin, distinctive characteristics.
 -polar and tropical air masses influence US
 -most originate over sea. those from land are drier
 -US influenced more by: polar air masses in winter/tropical air masses in
summer
 -[c]continental [m]maritime [T]tropical [A]arctic [P]polar
warm front: contact between warm air mass moving into area of cold air
 -as air masses move to midlats, they move E some
cold front: contact between cold air mass into warm-air area
jet stream: narrow, fast, Eastward-flowing air mass. Causes fronts.
 -above mid lats just below top of troposphere, 6miles high
 -follows wavy path; causes unusual weather by steering [P] or [T] too far
N or S
warm always rises above cold
temperature difference across cold front greater than warm front
 -so, rain of cold front usually heavier, briefer
Tropical cyclones: huge, rotating masses of low pressure: strong wind, torrential
rain
 -largest systems on Earth
 -no associated with fronts
hurricanes: name in N, S America
typhoons: W N Pacific ocean
cyclones: Indian ocean
energy of single hurricane greater than all that created in US in 20 years.
tropical cyclone begins as low pressure cells break from equatorial low pressure
belt, grows as heat energy from ocean picked up
 -the surface winds feed moisture [water vapor] into storm
 -the release of vast amounts of water’s latent-heat of condensation
power tropical cyclone.
Tropical cyclone classification:
 tropical depression: winds below 38mph
 tropical storm: 38<winds<74mph
 tropical cyclone: 74mph<winds
Saffir-Simpson Scale: hurricane intensity; further classifies; wind speed, dmg
250mph a high
100 tropical cyclones each year. conditions to create:
 ocean water temperature > 25C -> for evaporation
 warm/moist air -> supplies latent heat
 Coriolis effect; cyclone spin CCW in N hemis, CW in S hemis
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No cyclone directly on equator, because Coriolis is zero.
Happens on equator once every 300-400 years
June 1-Nov 30 “hurricane season” [not limited to this time frame]
hurricanes typically remain in tropics. Driven by trade winds so they move E to
W. Last 5-10 days.
If more over land, energy source is lost, so they dissipate
diameter avg 124miles but can be 500+
eye of the hurricane: low pressure center: air here spirals upward; usually calm
spiral rain bands compose hurricanes; several inches of rainfall per hour
storm surge: responsible for most of a hurricane’s dmg. [90% deaths]. Hill of
water
 -low pressure center produces hill up to 40ft high.
 -hill where wind blowing shoreward climbs shallow water onto shore.
Very bad at high tide.
 -dramatic increase in sea lvl at shoer
 -where onshore winds further pile water hit most severely
Galveston Texas, 1900; 7000 dead. Category 4.
Category 5 3x; 1935[Keys], 1969[Mississippi], 1992[Andrew FL]
Mitch [Central America 11k dead]
most of world’s tropical cyclone formed in water N of equator in West pacific
ocean.
1970 [Bangladesh 40ft Storm Surge killed 1 million] another in 1972; 500k dead.
’91; 200k
ocean climate patterns run E-W, are stable. modified by ocean surface currents.
equatorial: region spanning equator. abundance solar radiation. Major air
movement upward.
 -storms form here.
tropical: regions N/S to cancer, Capricorn. Strong trade winds. NE in N hemis,
SE in S hemis. Rough seas.
 -storms gain energy here.
subtropical: regions beyond tropics. High surface salinity. belts of high pressure.
little precipitation, much evaporation. Winds weak, currents sluggish. strong
boundary currents N-S, particularly along west margins.
temperate: regions [midlats] strong westerly winds; from SW in N hemis, NW in S
hemis. severe storms, heavy precip. winter esp
subpolar: regions; extensive precip due to subpolar low. sea-iced-covered in
winter, melts in summer. icebergs common, surface temp rarely greater than
41F in summer
polar: region; temps remain at or near freezing. covered with ice, most of year.
No sun in winter, all sun in summer
sea ice: masses of frozen ice. low temp/high lat
icebergs: break off [calve] from glaciers that originate on land
pancake ice: forming slush into thin sheet broken by wind and waves
ice floes: layer of ice when further freezing occurs to pancakes
rate of ice form slows as it thickens, because top ice insulates water below
calm water and low temp aid ice formation
most of dissolved substances remain in water, notice. Salinity increases under
ice.
 -decreases the freezing point of water
 -ice becomes ink below surface-> lower surface salinity water freezes in
place
17% decrease in overall ice extent
accelerated melting at interior poles
 -due to shifts in N hemis atmosphere circulation patterns
most breaking-up [calving] occurs in summer high temps
icebergs from in Greenland narrow valleys to ocean.
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 -E and W Greenland current carry bergs into N Atlantic shipping lanes
 -may take years to melt
shelf ice: thick floating sheets of ice formed at edges of glaciers in Antarctica
 [B-15 4250 sw mile iceberg from shelf ice breaking off]
 90% icebergs mass below sea lvl
 flat tops up to 650ft high. Most below 530ft high
 Larsen ice shelf decreased by 40% since 1997
 rate of warming; .5C per decade
Argo located Titanic 1985 Robert Ballard
World average temp Earth and troposphere: 15c [59F]
greenhouse effect: keeps Earth’s surface and lower atmosphere warm.
most of sun energy that reaches earth surface: short wavelength, visible almost
longer-wavelength infrared radiation; heat; short-wavelength energy converted to
this energy when it strikes the surface.
energy trapped in atmosphere by ozone layer
heat budget: 100 units shortwave solar radiation reflected, absorbed, scattered
by various components of Earth
 47% of solar radiation absorbed by oceans and continents
 23% absorbed by atmosphere and clouds
 20% reflected to space by backscatter, clouds, and Earth’s surface
peak of intensity of energy of sun; .0002inch wavelength, within visible spectrum
earth materials that absorb energy reradiate it back to space as longer
wavelengths: infrared [heat. .004 inch long]
rates of absorption and reradiation are equal
greenhouse effect produced by heat-trapping gases trapping reradiated heat,
and reradiating this heat once more.
change of wavelength from visible to infrared is the key to understand how
greenhouse effect works
solar radiation received at the surface is retained for a time in the atmosphere;
moderates temp day/night/seasons
water vapor contributes more to greenhouse effect more than any other gas.
 unaffected by human activity
CO2 concentration increase 30% over 200years
 -increase by 1.2ppm/yr
the other greenhouse gases, though lesser concentrations, are important,
because they absorb far more infrared radiation per molecule than CO2. But still,
not as important as CO2.
Melting glaciers, early springs, species distribution shift, rise in average temp all
indications
Avg temp up .6C in last 130yrs.
Possible effects:
 -higher sea-surface temp [more tropical storms, alteration in deep water
currents]
 -most severe drought, more intense precip
 -water contamination [larger outbreaks disesase]
 -longer/more intense heat waves
 -shift in distribution of life
 -melting ice caps [rising sea lvl]
possible that ice caps enlarge. how?: Warmer temp->more evp->more precip on
land->potentially increasing snowfall for creation of ice caps->lower sea lvl
some positives: increased growing season some places, plant like flourish w/
CO2
CO2 estimates prior to 1958 estimated from air bubbles in ice cores
Intergov’l Panel on clamate change [IPCC] 1988; 200 scientists begin studying
human effects on global warming; conclude that human impact exists.
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sedimentary rock and forests are natural storage places for organic CO2; being
released.
Kyoto Protocol: 1997; 60 nations; voluntary reduce emissions. US to reduce
emissions 7% below 1992 emissions by 2007: WE FUCKING WITHDREW! Also
to transfer technology to other countries with them becoming producers of much
greenhouse gas
2nd IPCC: 2001: 1.4-5.8C temp increase between 1990-2100
Oceans absorb lots of CO2
CO2 30x more soluble in water than other gases
more CO2 found in ocean than in atmosphere
 most of this CO2 incorporated into organisms ->photosynthesis
ocean acts as sink for CO2; soaks it up, deposits it as sea floor deposits.
by removing more CO2 from ocean, it can absorb more
iron hypothesis: John Martin 1987; productivity low in tropical regions because
absence of iron, he proposed fertilizing ocean with iron.
adding iron to ocean increase productivity up to 30x
long term effects adding iron and CO2 to ocean are unknown
 fear of oxygen depletion in these areas. some companies filed patents
pump emissions into deep-ocean reservoirs
SOFAR channel: layer of ocean at 1000m caused by temperature and pressure
conditions causing sounds from above and below to become bent in layer. Sound
is trapped, transmitted long distances
Walter Munk: to use channel to detect global warming. ATOC exp
speed of sound in seawater increase as temp increase.
Lecture Chapter 6 continued
o Low pres; CCW rot
o high pres ; CW rot
o more evaporation over low pressure
o most weather generated at seas
o hurricane wind speed: at least 74mph
o air exiting eye of hurricane comes out at left, but then once free, curves right
o Coriolis affect ocean and atmosphere:
 causes Hadley cells
 causes W ocean basin current intensity [Gulf Stream]
 causes CCW; tornadoes, hurricanes
o “Fixed Reference Frame” -> “intertial frame”
o gravity does not affect direction
Wrong Answers from Site
o Air rises at 60 degrees latitude and falls at 30 and 90.
o Sun is directly over equator at both vernal and autumnal equinox
o Water vapor contributes the most to greenhouse warming
o Land breeze flows from land to sea
o Wind belts created by lowermost portion of circulation cell
o Surface winds of anticyclone in S hemis go CCW
o most abundant gas in atmos is nitrogen
o least abundant gas is carbon dioxide
o polar easterlies between 60-90 degrees
o polar front at about 60 degrees
o increase earths tilt; warmer summers, cooler winters
o Coriolis; CW rot around high, CCW rot around lows
o air moves in and up in low pressure areas
o surface winds in tropics [trade] blow W and toward equator
o midlat storms: contrasting air masses, jet stream, westerlies, polar front
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cause hurricanes: trade winds, warm ocean, water vapor rich warm air, jet
stream
more intense storms maybe with global warming
Chapter 7
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ocean current: masses of ocean water from one place to another. Any mass, Any
depth, simple or complex.
huge current system dominates surfaces, transfer heat from warmer to cooler
areas.
transfer 1/3 of heat, wind belts transfer 2/3
sun drives surface currents
closely follow windbelt patterns
cold currents flowing toward equator on W sides of continents produce arid
conditions
warm currents flowing poleward on E sides of continents produce warm, humid
conditions
ocean currents contribute to mild climate of N Europe and Iceland; conditions at
similar lats along Atlantic coast of N America much colder.
currents deliver ocygen in cold, dense water, and they helped prehistoric peoples
travel
currents either wind or density driven
surface currents: caused by wind belts parallel to the surface. Horizontal
deep currents: caused by cold, dense water sinking. vertical
surface currents rarely flow in same direction at same rate
 -measuring is difficult: can be measured directly or indirectly
 -some consistency exists in overall surface current pattern
Direct measurement:
 1]floating device placed into current; tracked through time
 2]place device in current from fixed position
Indirect measurement:
 1]determine the internal distribution of density and the corresponding
pressure gradient across an area of the ocean
 2] radar altimeters [TOPEX/Poseidon satellite 1992]: determine bulge’s
in sea surface which are results of the shape of the underlying sea floor
and current flow. dynamic topographic maps produced from this data that
show speed/direction of surface currents
 3]Doppler flow meter to transmit low-frequency sound signals through
the water. measures shift in frequency between the sounds water
emitted and those backscattered by particles in the watter to determine
current movement.
deep current measurement:
 -more difficult to measure because of depth
 -mapped by:
 -device carried with current
 -tracking telltale chemical tracers
 -some traces absorb into seawater, other intentionally added
 -useful tracers [tritium from atom bomb
tests][chlorofluorocarbons freons and other gases]
 -measure temp/salin characteristics of deep ocean currents
surface currents occur within/above pycnocline to a depth of 1km
surface currents only affect 10% of ocean water
due to friction with wind
2% of winds energy transferred to ocean surface. 50-knot wind produces a 1knot current
if not continents, surface currents would follow major wind belts.
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-interaction between trade winds and prevailing westerlies creates
circularmoving loops of water in Atlantic ocean
gyre: large, circular-moving loops of water driven by major windbelts.
subtropical gyres: 1]North Atlantic 2]South Atlantic 3]North Pacific 4]South Pacific
5]Indian Ocean [mostly S]
 -coincide with subtropics at 30 N, S lats
 -CCW in S hemis. CW in N hemis
Each composed of 4 mains currents that flow into one another:
 equatorial currents: motion trade winds b/w tropics. From SE in S hemis,
NE in N hemis.
 -travel westward along equator: form equatorial boundary current
of subtropical gyre.
 western boundary currents: caused by coriolis effect deflecting the
equatorial currents that have reached a continent away from the equator.
 -Western boundary of subtrop gyres
 Northern/Southern boundary currents: B/w 30 and 60 lat: caused by
prevailing westerlies from NW in S hemis and SW in N hemis. Direct
currents easterly.
 -comprise Northern for N subtrop gyres, visa verse for S
 eastern boundary currents: Coriolis effect and continental barriers turn
currents toward equator when they flow back across the ocean basins
 -eastern boundaries of subtrop gyres
equatorial countercurrents: water on western margins flowing downhill under
influence of gravity due to avg sea lvl at westward margins being as much as 2m
higher than on eastern side.
 -flow east
 -apparent in pacific
 -affected by shape of continents in Atlantic
 -strongly influenced by monsoons in Indian ocean.
subpolar gyres: currents [of prevailing westerlies] moving westerly by polar
easterlies
 -at 60 lat
 -rotate opposite the adjacent subtrop gyre
 -smaller and fewer than subtrop gyres
Fridtjof Nansen: 1861-1930; Norwegian explorer; voyage in unexplored Arctic
Fram: his ship. 39m. wooden; designed to be pushed to surface by freezing
water
nansen bottle: for collecting water samples at depth
Arctic ocean ice moves 20-40 to the right of wind blowing across its surface
 -in S hemis, surface currents move to the left of wind direction
V. Walfrid Ekman: [1874-1954]; Swedish physicist; developed:
Ekman Sprial: explains Nansen’s observations in accordance with Coriolis effectl
describes speed/direction of flow of surface waters at various depths
o -assumes a uniform column of water set in motion by wind blowing
across surface
o -N hemis: immediate surface water flow 45 to right of wind [S hemis left]
o -as surface water moves, it sets in motion other “layers” beneath it
current speed decreases with incrasing depth, and coriolis effect increase
curvature to right
at same depth, water may move exactly opposite the direction the wind that
started it is going.
deep enough water, friction consumes energy of wind and there’s no motion:
normally occurs at 100meters.
Ekman Transport: All layers combine to create new water movement that is 90
from the direction of the wind. 90 right of wind in N hemis, left in S hemis
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-nothing is ideal: Ekman Transport in open ocean is typically 70, nearly
same direction as wind in shallow coastal waters
subtropical convergence: water in middle of a gyre, causing water to literally pile
up in center of subtrop gyre. caused by Ekman transport causing CW rotation
within ocean basin
 -resulting in all subtrop gyres having a 2meter high hill
geostrophic current: when coriolis effect and gravity balance, causing the water
wanting to fall down the hill to move around it.
 -path of the ideal geostrophic flow
 -hill has a steeper westward slope
 -path of actual geostrophic flow: friction results in this current eventually
downhill
El nino event affects currents greatly
S Pacific less intense than other gyres, because large area, many islands.
there is a narrow and strong flow to north on western side of subtrop gyres in N
hemis.
narrow strong flow to South in S hemis [still on W boundary of gyre]
general: western boundaries of subtrop gyres faster, narrower, deeper
 -due to apex being closer to W side
 -Kuroshio 15x faster, 20x narrower, 5x as deep as Cali current
western intensificiation: this phenomenon: currents affected by this are western
intensified
 -ALL W boundaries of subtrop gyres are western intensified
 -Coriolis effects eastward, high lat water, making it turn toward equator
more strongly;
 -causes wide, slow, shallow flow of water toward equator across
subtrop gyres [picture a funnel]
-surface currents directly influence climate of adjoining landmasses
 -warm current; warm air; rain over continent
 -continental margins with warm offshore currents typically have humid
climate [E coast]
 -temperature migrate N-S with seasons
 -continental margins with cold offshore currents typically have drier
climate [W coast]
Upwelling: vertical movement of cold, deep, nutrient-rich water to surface
Downwelling: surface water -> deeper
productivity: presence of microscopic algae
 -cold water= better productivity supports larger marine life
downwelling less productivity, but carries oxygen dissolved to deep-ocean life
current divergence: surface water away from an area on ocean’s surface:
equator
geographical equator: 0 lat
meteorlogical equator: ~5lat N
equatorial upwelling: caused by trade winds causing current divergence ->
Ekman transport causes surface water N of equator to veer right [Northward] and
water south of equator to veer left [southward]: divergence of surface current
along geographical equator
 -high productivity
current convergence caused by currents movement toward each other
 ex] N Atlantic; Gulf Stream, Labrado, E Greenland currents come
together
water piles, sinks
coastal winds can cause either welling due to Ekman transport
coastal upwelling: caused by coastal wind from the S [in S hemis] causing
Ekman transport to move coastal water to the left, away from coast [on a western
coast of continent] Water from below rises to replace this water
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 -W coast US experience this. Natural air conditioner in the summer
coastal downwelling: just the opposite.
both upwelling and downwelling common in high latitudes
absence of pycnocline allows lots of vertical mixing
upwelling also caused by: offshore winds, seafloor obstructions, sharp bend in
coast.
Chapter 7 Lecture
o Most productivity in coastal areas
o summer in Arabian sea, wind blows SW->NW with respect to India
o eastern boundary currents greatly affected by coriolis effect
o ice dam cold water into oceans would hinder N Atlantic circulation
Chapter 7 cont…
Antarctic circulation dominated by movement of water mass South of 50 S lat
anarctic Circumpolar Current [West Wind Drift]: main Antarctic current; encircle antarctica
W->E at 50 S lat, but varies b/w 40 and 65 S lat directed from Antarctica
subtropical convergence: 40 S lat; N boundary of ACC
ACC powered by prevailing westerly wind belt “Roaring Forties, Furious Fifties,
Screaming Sixties”
Antarctic Convergence [Antarctic Polar Front]: 50 S lat: cold dense Antarctic meets and
sinks below warm less-dense sub-antarctic waters. Marks N boundary of southern/Antarctic
ocean
East Wind Drift: surface current propelled by polar easterlies. E->W
-most developed in Wedell and Ross seas.
-directed toward Antarctica. closer to cont than ACC
Antarctic divergence: around Antarctica where East wind drift scrapes ACC
-much marine life during S hemis summer b.c of upwelling created here
Gulf Stream: N along US coast. Best studied of all ocean currents. W-boundary current.
31-47m wide. Fastest in world. W boundary of gulf stream is abrupt. E boundary not so much.
Sargossa Sea: the water that circulates round rotation center of N atlantic gyre.
“stagnant eddy”
transport off Chespeak bay 100 sverdrups [ more than 100x great than combined
flow of all world rivers]: water from Sargossa sea combining with Florida current
-this water from Sargossa sea returns at Newfoundland.
meanders: snaked-like bends in current which often disconnect from gulf Stream
and form large rotating masses of water called vortexes, eddies, or rings.
-mechanisms that produce the dramatic water loss as Gulf S moves N yet to be
determined
warmcore rings: warm Sargossa sea water surrounded by cooler water. Shallow
bowl-shaped, 1k deep. 68m wide. These spin off the Gulf Stream to the North, rotating CW
coldcore rings: cold nearshore ring. cone-shaped. 2.2m deep. 310+ miles wide,
increasing with depth, sometimes reaching sea floor. These spin off of Gulf Stream to the South,
CCW. move SW 2-4m/day; often rejoin GS at Cape Hateras. Impact sea floor sed.
-both rings: unique temp chars, biological pops; warm-water organism in cold
ocean and visa versa; can survive as long as ring does, 2yrs sometimes.Coldcore rings last
longer, and have more life.
Ben Franklin postmaster discovered Gulf Stream.
Labrador current: with the gulf stream form much fog in N atl, then break into
Irminger current along Iceland’s W coast and Norweigan current moving N on Norway’s coast
North Atlantic Current: crosses N atlantic. turns south to become canary current.
Gulf Stream moderates E coast temp and N Europe temp, so temps across
atlantic in Europe much higher even though on same lat, b/c of heat transfer from GS to Europe.
Spain, Portugal at same lat as NE states.
-as much as 20F warmer
-the difference b/w S and N temp on E coast much greater than b/w N and S
coasts of Europe.
equatorial counter current of pacific better developed in pacific
Walker Circulation Cell: in equatorial S pac: caused by pressure difference between W
and E pacific. SE trade winds blow across pacific.
-1920 effect first describe; Sir Gilbert Walker.
Normal conditions: walker cell rotates CW. Low pressure in the West, high pressure in
the E
pacific warm pool: warm water flowing in equatorial regions creating a wedge of warm
water on the western pacific. Thermocline below 100m
-thermocline in E is generally within 30m of surface
El Nino: current equatorial around Christmas: intense rainfall. CC air rotation
southern oscillation: name given to phenomenon of E-W pressure seesaw accompanying
the warm current.
El Nino South Oscillation [ENSO]
o El Nino; low pressure along equatorial regions in S America. SE trade winds
diminish, sometimes reverse. CCW air rotation
 -warm pool flows back from west
 -begins to move in sept: at S American in dec/jan
 -water off S American coast up to 18F warmer than normal
 -sea lvl increase as much as 8in [thermal expansion along coast]
 -increases number of tropical storms
 -thermocline flattens; more horizontal
 -downwelling sometimes occurs
 -productivity diminishes, life reduced
 -high pressure replace Indonesian low; dry conditions
-La nina [cool phase]
-closer to normal conditions
-stronger walker cell instead of reverse one
-stronger trade winds
-more upwelling
-shallower thermocline in e pac
-band of cooler than norm water stretch across equatorial S pac
-commonly occur right after Nino
ENSO Index: show alternating conditions since 1950 between Nina, Nino.
-Calculated by atmospheric pressure, winds, sea surface temp
-possitive numbers=Nino negative numbers=Nina zero=normal conds
El Nino occurs avg every 2-10 years. Irregular pattern
-lasts 12-18 months
-some can last for years
-more El Ninos in early 22nd century
-most severe in 20th: 1982-1983
Pacific Decadal Oscillation [PDO]: lasts 20-30 yrs. Influence Pac surface temps
-pac in warm stage of PDO from 1977-1999, just having entered cool phase
[Marine Galapagos Iguanas shrink]
-mild nino affect only S pac ocean. severe affect world temp
-difficult to predict
-can result in: flooding, erosion, droughts, fires, tropical storms, and effect marine life.
La Nina sea surface temp and weather opposite of Nino
El Nino events do occur in ocean basins
Tropical Ocean-Global Atmosphere [TOGA]: 1985 study how El Nino event develop.
predict el nino 1 yr
Tropical Atmosphere and Ocean [TAO]: After TOGA: continues to monitor. 70 moored
buoys.
Indian counter current flow between 2 and 8 S of equator instead of N b/c Indian ocean
is mostly in S hemis.
monsoon: N Indian ocean wind pattern
northeast monsoon; atmospheric masses off Asian continent into Indian ocean. From NE>SW during winter
because of low heat capacity of land, continent heats faster than ocean in summer,
creating low pressure area, resulting in the winds reversing: southwest monsoon: thought of as
continuation of SE trade winds across equator.
North equatorial current gone during summer, replaced by southwest monsoon current W
to E
Agulhas current: S along African coast, joins ACC
Aghulas Retroflection: abrupt turn as current collide [ACC]
deep ocean current affect 90% of ocean water. moves more water slower 6-12 miles per
year.
take 1 year for 1 hr travel of surface current for deep current
thermohaline circulation: deep ocean circulation because differences in temperature and
salinity cause dense differences
density and salinity remain mostly unchanged in deep ocean
temperature-salinity diagram: identify deep water masses by temperature, salinity, and
density.
isothermal water column makes for easier up and down welling.
Antarctic bottom water: formed under sea ice in s subpolar lats in Antarctic continental
margins. Sink down Antarctica continental slope. Densest water in open ocean. spreads into all
ocean basins. returns to surface in 1000yrs.
North Atlantic Deep Water: from: Irminger Sea, Labrador Sea, Med Sea, Norwegian sea.
moves to all ocean basins. less dense; sits on top of Antarctic bottom water
no sinking at subtrop convergences
arctic convergences: mass sinking occurs
antartic intermeiate water: formed sinking at Antarctic convergence. ;east studied water
mass.
no vertical mixing at low lat, much vertical much at high lat
ocean common waters: mix of antarctic bottom water and north atlantic deep water. lines
basins of Indian and pacific oceans because no access to N hemis deep water.
surface water of pac to salin to sink, Indian too warm to sink
difficult to identify where verticle flow to surface occurs. every liter water that sinks much
rise
supposedly greater in low lat areas
also, deep water moving along rugged topography produces upwelling
most intense deep water flow along western side due to coriolis and bathymetric features
conveyer belt circulation: model combing deep and surface currents
cold water dissolve more oxygen than warm water.
in past, warm water probably was more a part of deep water
conveyer belt circulation initiated in Atlantic.
Chapter 7 Online Wrong
o ocean currents driven and energized by solar heat
o transfer 30% heat from tropics to poles
o West Wind Drift part of: North pac gyre, S Atl gyre, Indian gyre
o Surface water does NOT move at angle to wind direction
o Ekman transport results in water piling at center of gyre
o areas with well-developed pycnocline have little downwelling
o NOT result of El Nino climate:
 inc water temp/destruction coral in E pac
 inc sea lvl E pac
 more hurricanes E pac
o cold downwelling water=100 amazon river volumes.
Chapter 8
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disturbing force: energy that cause ocean waves
 -rock thrown into pond: release of eng causes waves
wind generates most waves; radiate in all directions
waves created between fluids [water, air] and within them
ocean waves: air-water interface [movement air across ocean]
atmospheric waves: air-air interface. movement of different air masses. common
at cold fronts. ripple-like clouds
internal waves: water-water. movement of different water densities, along
boundaries. associated with pycnocline. larger than ocean waves. can be seen
from space. dangerous for submarines. can’t “break” except in essence. created
by tidal movement, turbidity currents, wind stress, passing ships.
sea floor movement->large waves
waves are energy in motion. the energy moves within them but does not affect
their movement.
progressive waves: oscillate uniformly, travel without breaking: longitudinal,
traverse, orbital
 longitudinal waves: [push-pull waves] particles push and pull in same
direction the the energy travel
 sound is longitudinal waves
 longitudinal can be in all forms of matter
 traverse waves: [side to side] eng travel at right angles to direction of
vibrating particles
 rope to doorknob, wave rope up and down to produce waves
 traverse only through solids
 longitudinal and traverse waves called body waves
 ocean waves are body waves, and since they involve aspects of
longitudinal waves and traverse waves, they are orbital waves
sine waves: idealized waveforms that do not exist in nature
crests: high parts of waves
trophs: low parts of waves
still water lvl: halfway b/w crest and troph. zero energy lvl. lvl of water if not
waves
wave height [H]: verticle distance b/w crest and troph
wavelength [L]: crest to crest. troph to troph.
wave steepness: ratio of height to wavelength-> H/L
 exceeds 1/7, wave breaks, b/c it cannot support itself
 1/7 is also the maximum height
wave period [T]: time for 1 wavelength to pass a fixed position. typically 6-16s
frequency: 1/T
circular orbital motion: water moving in a circular motion to pass wave energy
along
floating objects move up and back as crest approached
up and forward as it passes
down and forward after it passes
down and back as troph approaches.
so, object moves in a circle to return to a spot slightly forward of its original
position
wave drift: orbit in the troph is slower than at the crest. accounts for slight forward
movement.
water particles orbit but waves more forward
circular orbit of an object at surface has diameter=wavelength
wave base: where circular orbital movement is negligible= L/2, measured from
still water lvl.
longer the wave, deeper the base
easier to swim below waves than to fight them at the surface
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deep water waves: if water depth [d]> L/2. have no interference with ocean
bottom
wave speed [S]: rate at which a wave travels L/T. celerity
 celerity used only in relation to waves no mass moving, just wave form
 speed depends on wavelength
 longer the wavelength, faster the wave travels
 so, fast wave not neceissarily have great height, b/c S only dependent on
L
shallow water waves: wave with d<1/20 of L. long waves S=d/T
 ocean floor interferes with their orbital motion
 speed of these waves influenced by gravitational acceleration [g] and
depth [d]. mostly by depth
 deeper the water, faster the wave
 include: tsunami, tides, and wind-generated waves moved into shallow
nearshore areas.
 tsunami, tides very long L [greater so than ocean depth]
 particle movement: flat elliptical orbit
transitional waves: some characteristics of shallow and deep water waves. L b/w
2 and 20 times the water depth. Speed depends on L and d.
wind creates pressure, stress
capillary waves: L-1.74cm. ripples. small, rounded, v-shaped troph
restoring force: destroy capillary waves, restore smooth surface. Capillarity
dominant
gravity waves: symmetric waves with L>1.74cm. gravity more dominant restoring
force. L is 15-35x their height. trochoidal waveform.
“Sea”: where wind-driven waves are generated. choppy, many direc.
energy in waves: 1] wind speed 2] duration [of wind in 1 direction] 3]fetch
[distance wind blows]
whitecaps: open ocean breakers
Beaufort Wind Scale: describes all appearances of sea
 sir Francis Beaufort of British Navy
Ramapo and wave H 1935
fully developed sea: equilibrium condition. when waves can no longer grow
swells: long-crested part of “sea.” waves that have traveled out of their area of
origination
 reason for waves at windless shore
wave trains: groups of waves that follow out of the sea area the faster waves
wave dispersion: the sorting of waves by their L
longer waves outrun shorter waves
decay distance: distance waves change from choppy sea to uniform swell. can
be hundred miles
as train moves, front wave disappears over and over, but # of waves remain, b/c
new wave forms in back of train
train moves at ½ velocity of any individual wave in group, b/c of this progression
interference patterns: swells from different storms run together. sum of
disturbance that each wave would have produced individually.
 constructive interference; wave with same L->crest to crest, troph to
troph-> height increases
 destructive interference: wave with same L->crest to troph->height
decreases
 mixed interference: different L
 surf beat: varied sequence of high and lower waves
surf zone: zone of breaking wave at continental margins
shoaling: becoming shallower
any sunken obstacle causes waves to lose energy
breaking wave indicates shallow water
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wave speed decreases as water shoal. L decreases. H increases. increase wave
steepness [breaks at 1/7]
swell from far off storm break near shore. parallel lines of uniform breakers
local wind waves not swell break further off shore; rough, choppy, irregular
depth of water where waves breaking is 1.33x breaker height
waves break in surf zone because particle motion at bottom of wave restricted
 bottom wave slower than top, which subsequently topples over
rogue waves: unusually large waves
spilling breaker: turbulent mass of air and water running down slope of wave. low
overall eng. result at gently sloped ocean bottoms. long, boring surfing.
plunging breaker: curling crest move over air pocket. particles in crest outrun the
wave. form on steep beach slopes.
surging breaker: build up and break right at shoreline. caused by abrupt slope.
refraction: bending of each wave crest as wave approaches shore
waves bend almost parallel to shore
refratction of waves along irregular shoreline distributes wave energy unevenly
along shore
orthogonal lines: wave rays. indicate direction waves travel: spread so that
energy between lines is equal at all time.
 -converge on headlands jutting into sea
 -diverge in bays
wave reflection¨: wave reflected back into ocean with min loss of eng. reflected
most often at angle.
the wedge: W of jetty that protects harbor entrance at Newport, Cali.
standing waves: stationary wave. produced by waves reflecting at 90 deg. sum of
2 waves with ame L traveling in dir directions. no circular motion.
nodes; no movement. horizontal
antinodes; movement. vertical
tsunami: large destructive waves. NOT tidal waves. seismic sea waves
 most cause by fault movement; vertical, not horizontal displacement.
splash waves: above water landslides or meteor impact tsunamis
tsunami L-125miles avg can be felt 62 miles deep. S=435mph in opean ocea.
5meteres high
they are more like an increase/decrease in sea lvl than a breaking wave
typically are a series of waves. largest surface in generally the later surge
extremely large/destructive every 15-20years. 57 noticeable tsunami per decade.
86% in pacific.
 Krakatu eruption [1883] 36k dead from tsunami.
Pacific Tsunami Warning Center [PTWC]: coordinates infor from 25 pacific rim
countries. HQ in hawii. 50 measuring stations
tsunamigenic->capable of producing tsunami
transform faults do not create tsunami
best to move ships out to sea open ocean
10 megawatts per .6m of shoreline with wave power harnessing
LIMPET 500: 1st commercial wave power plant. 2000
more wave energy along W coast than E coast. largest waves associated with
prevailing westerlies.
Chapter 8 Wrong
o internal wave occur at strong steady pycnocline most
o tsunami from Hawaii 5 hours to reach W coast.
o surf zone is where waves are actively breaking
o velocity of wave decreases once it touches bottom
o wave fronts of storms are beyond the “limit of the storm”
o storms and tidal movements are also disturbing forces
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ocean waves cannot: be described by the way they form, be described by T, L,
H, and not by the way they form
Orbital waves=Swell!!!!!
ocean waves are oribital waves
body waves: longitudinal and traverse
1 meter high tsunami with a bigger wave base than 1000m long wave
we can determine S if we know L, T, F
either interferences [destruc, construc] caused by either refraction or reflection
Chapter 9
tides: periodic raising and lower of avg sea lvl.
450 BC Hertodotus observe tides in writing.
Issac Newton 1642-1727 universal law gravitation
barycenter: 1k miles beneath surface earth. earth and moon rotate around these.
gravity pulls all water on earth to moon and sun
tides generated by forces imposed on earth generated by combination of gravity and
motion among earth, moon and sun
gravitational force: derived from Newton’s law: every particle of mass in the universe
attracts every other particle
if mass increases, gravitational force increases
if distance increases, gravitational force greatly decreases
the greater the mass of objects and the closer they are, the greater they attract
zenith: pt closest to moon, greatest grav attraction
nadir: pt furthest from moon, weakest grav attraction
at angles. causing grav attraction b/w each particle and moon be slightly different
centripetal force: required to keep planets in orbit. inward center-seeking force. provided
by grav attraction b/w planets and sun
broken string, ball flies tangent to orbital pattern
gravity supplies centripetal force
particles identical mass rotate in identical sized paths due to E moon rot sys
each req identical centrip force to maintain circular path
supplied force: [gravitational attraction between particle and moon] dif from
required force [b/c grav att varies with ditance from moon]
resultant forces: b/c of above difference. the mathematical dif between two sets of arrows
[centripetal force=req force; gravitational force=supplied force]
red arrow to black area at pt of beginning
avg 1 million the magn E grav
if res force vertical; at nadir and zenith arrow outward, and along “equator” N and
S arrows downward. no tide effect
tide-generating forces: if resultant force significant horizontal to E surface: produce tidal
bulges. small forces, but max at 45deg relative to NS “equator”
gravitational attraction inversely proportionate to the square of the distance
between two masses.
tide-gen force inversely proporationate to the ccube of the distance between
each point on earth and center of moon or sun
distance more highly weighed variable for tide-gen force
tide-gen force pushes water into bulges oat zenith and nadir [Lunar bulges]
side facing moon bulge is because grav force>centripetal. side away
from moon is because centripetal>grav force.
bulges are equal. all pts on earth experience 2 tides per day except the
poles
atmospheric tides: can be miles high. solid-body/Earth tides: within interior of Earth;
stretch skin of earth by centimeters
there is tide in glass of water
tidal period: time b/w each tide [2 per day] 12 hours ideally at equator
lunar day: 24hr 50m, moon overhead to overhead
solar day: 24hr, sun overhead to overhead
moon rises 50min later each day, high tides occur 50 mins later each consecutive day.
solar bulges: caused by sun; at closest and furthest distance from thereof
sun 27mx bigger than moon
sun tidal attract is less than moon because sun is 390x farther from earth
solar bulges 46% of lunar bulges
flood tide: tides appear move toward shore
ebb tide: away shore
but; earth’s rotation carries various location into and out of the tidal bulges, which are
fixed relative to sun and moon
monthly tidal cycle 29.5 days; this is how long it take moon to orbit earth
new moon: moon between earth and sun; can’t be seen at night/ conjunction
full moon: moon opposite side of sun. fully visible. opposition
quarter moon: half lit half dark. moon at 90 deg angles with E relative to sun
tidal range: vertical difference between high and low tides
very large at new and full moons
spring tide: max tidal range. 2x per month
syzygy: call the moon during full and new.
at quarter moon, lunar/solar tide working at right angles
neap tide: small tidal range; destructive interference
quadrature: call the moon at quarter moon
time b/w spring tides or neap tides is ½ monthly lundar cycle: 2 weeks
time b/w spring and neap tides is ¼ monthly lunar cycle: 1 week
waxing crescent: new moon to first quarter moon
waxing gibbous: first quarter moon to full moon
waning gibbous: full moon to third-quarter
waning crescent: third quarter to new moon
moon has synchronous rotation: identical periods of rotation
“blue moon” once every 2.72 years.
declination: angular distance of sun or moon above or below Earth’s equatorial plane
ecliptic: imaginary plane containing the invisible ellipse on which E revolves around the
sun.
max declination of sun relative to Earth’s equator is 23.5
plane of moon’s orbit tilted 5deg with respect to ecliptic
so, max declination of moons orbit relative to Earths equator= 28.5
changes dec from N to S during the miltiple lunar cycles within 1 year
so, tidal bulges are rarely aligned with the equator [as is ideal]
earth 92.2million miles from sun during N hemis winter. 94.5 million miles during summer
distance b/w E and sun varies 2.5% over course of year
perihelion: earth nearest to sun. tidal ranges large. January
aphelion: earth furthest from sun. tidal ranges small
greatest tidal ranges in Jan each year
moon around earth elliptical, E-M distance varies 8%
perigee: moon closest to earth. largest tidal ranges
apogee: moon furthest from earth. smallest tidal ranges
moon cycle: perigee, apogee, back to perigee every 27.5 days
proxigean: spring tide coincide with perigee. especially high tides. storms heavy dmg
now.
also, spring tide graeter range during N hemis winter
max spring tide once every 1600 yrs
declination of moon determines position of tidal bulges
neither the 2 high or 2 low tides of same H b/c of declination of moon and sun
tidal moves more as forced waves with their speed determined by ocean depth
435mph avg.
bulges don’t exists, because they’re too slow
cells: what ocean tides break up into instead
amphidromic point: near center of each cell, around which crests and trophs of tide wave
rotate.
no tidal range here
cotidal lines: radiate from amphidromic point: connects point where high tide occurs
simultaneously.
tide wave rotates CCW in N hemis, CW in S hemis
wave complete 1 rotation during tidal period [12 lunar hours] limits size of cells.
low occurs 6 hrs after high in amph cell
high on “10” cotidal line, low must be occurring on “4” cotidal line of cell
inc turbulence and mixing strongly affect tides. tidal waves breaking conts produces
internal waves
over 150 factors affect tides at given coast
effect: high tide rarely occurs when moon at apogee. vary place to place
mathematical model beyond limits of scientists
diurnal tidal pattern: single high and low tide each lunar day. tidal period= 24hr 50m.
common in shallow inland seas
semidiurnal tidal pattern: 2 high and low tides each luner day. H of successive H and L
tides approx the same, NEVER exactly. tidal period: 12hr, 25m
common along atlantic coasts of us
mixed tidal pattern: character of both above. successive H and L very different H
[condition called diurnal inequality]. Tidal period typically 12hr 25m, but can exhibit diurnal period
too.
most common type; pac coast N America
bay of Fundy: largest tidal range
rotary current: produced by current rotation CCW in N hemis basin. In open portion of
basin
reversing current: moves into and out of restricted passages along coast. caused by
increased friction in nearshore shoaling waters. once a rotary current.
rotary currents less .6mph. reversing currents up to 28mph in restricted channels.
rev currents in mouths of bays
flood current: produced when water rush into bay/river with incoming high tide.
ebb current: produced when water drains from bay/river because low tide approaching
high slack water: occurs at peak of each high tide
low slack water: peak of each low tide
during these times, no currents occur more some minutes
reversing currents cause navigational hazards, but prevent sed build-up and replenish
bay nutrients
tidal current significant even at depths
whirlpool/vortex: rapidly spinning body of water. cause by rev currents.
most common in shallow passages connecting 2 large bodies water with
difference tidal patterns/cycles
up to 10 mph
Maelstrom off N coast Norway is strongest in world
Datum: MLLW; avg of 2 low slack waters
tidal bore: wall of water that moves up low-lying rivers due to incoming tide.
to 5m high/14 mph. develop where large tidal range, loww-lying river exists.
due to resistance of river flow. Chientang River [China] has the largest bore.
grunion: slender silvery fish that spawns on land.
Chapter 9 Wrong
no neap tide during solar eclipse
open ocean tidal current rotary
strongest gravitational force=highest tide
go collecting during spring tide [great tidal range]
ideal high tide interval; 12hr 25m
force of gravity not related to velocity
plane of solar system= eclictic plane
moon over equator will not describe tropical tides
tidal waves are thousands of kilometers, and are deep water waves
centripetal force act perpendicular to the solar gravitational force
side of earth closest to sun, high tides not form due to gravitational forces
tidal forces not greatest at sygyzy
semidiurnal tides result in 2 predicatable lows every day
Chapter 10
US 80% pop coastal
waves crash on most coasts 10k per day
shore: zone between lowest tide lvl and highest elevation on land affected by storm
waves
coast: inland from shore as far as ocean-related features can be found
shore and coast greatly vary
coastline: boundary between shore and coast
backshore: above high tide shoreline-> water covered only during storms
foreshore: submerged at high tide, exposed at low tide.
shoreline: water’s edge. follows tide
nearshore: seaward from low tide shoreline to low tide breaker line
-never exposed. affected by waves
offshore zone: beyond low-tide breakers. waves rarely affect bottom
beach: a deposit of the shore area
wave-cut bench: flat, wave-eroded surface
bench is the entire active area of coast that experience changes due to breaking waves
recreational beach: area of beach above shoreline
berm; dry, gently sloping region at foot of coastal cliffs or dunes.
beach face: wet, sloping surface extend from berm to shoreline
more exposed low tide. also called low tide terrace
longshore bars: beyond beach face: 1 or more; sand bars parallel coast. these “trip”
water
longshore troph: separate longshore bar from beachface.
notch: between coastline and berm.
order: coastline-notch-berm-high tide shoreline-beach face-low tide shoreline-wace cut
bench-longshore troph-longshore bar-low tide breaker line
beach sediment finer from rivers that drain lowland areas than highland areas
mud coasts: Suriname, SW India
beaches: material in transit along shoreline
movement parallel and perpendicular to coast
swash: water from broken wave running up beach face. soaks in.
backwash: drains back. picking up sed
whichever is dominant dictates deposition or erosion
light wave activity – more swash. wide, developed beach
heavy wave activity-less swash, more backwash. New wave swash on top of old
wave backwash. removed sand creates bars
Chapter 10 wrong
a beach on low relief tropical island made mostly of calcium carbonate
isostatic rebound CANNOT produce global sea lvl rise
barrier flat is the woodland above the salt marshes, which are closest to lagoon
shore includes from low tide line to notch
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