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wind driven circulation- lecture?

Genie V 7 questions

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  1. 1the oceans droves the [blank_start]wids[blank_end] as they drive the pressure systems, bc stoes the [blank_start]solar[blank_end] energy, which in term drives the [blank_start]oceans[blank_end]
    as oceans warm there is more [blank_start]evaporation[blank_end], so more energy going to the atmosphere, so more h[blank_start]urrican[blank_end]es
    wind [blank_start]driven[blank_end] zones are where a lot of the b[blank_start]iolo[blank_end]gy happens
    [blank_start]corriolis[blank_end] is the f factor, other factors are called the fx s, eg ti[blank_start]de[blank_end]s and winds, winds are important not just in the surface- cause variability in upper layers of ocean- the layer above the [blank_start]thermocline[blank_end]
    seeing more wind and wave damage at higher [blank_start]latitudes[blank_end] bc more [blank_start]energy[blank_end] in the oceans.
    winds are important bc difficult to work with them stronger than a [blank_start]force[blank_end] 6
    wind driven [blank_start]upwelling[blank_end] zones of the oceans account for around 25% of worlds pr[blank_start]oductiv[blank_end]ity
    corriolis manly ffects things wich take longer, ie not plugholes bc the earth hasnt [blank_start]moved[blank_end] that much wilst its draining
    [blank_start]wind[blank_end] driven forcing is the biggest effect on the ice flow, goes to the right in the [blank_start]northern[blank_end] hemisphere
    make measurements through the water column-, used an Ekman current meter, which is an early form of the [blank_start]current[blank_end] meter, uses clockwork and a series of [blank_start]ball[blank_end] bearings which drop into little slots below it to get [blank_start]direction[blank_end]. The clockwork releases a certain number of balls per [blank_start]minute[blank_end] to tell you what the [blank_start]speeds[blank_end] doing, don’t refer to this as a method of contemporary current measurement.
    1. Awinds
    2. Bsolar
    3. Coceans
    4. Devaporation
    5. Eurrican
    6. Fiolo
    7. Gdriven
    8. Hcorriolis
    9. Ithermocline
    10. Jlatitudes
    11. Kenergy
    12. Lforce
    13. Mupwelling
    14. Noductiv
    15. Omoved
    16. Pwind
    17. Qcurrent
    18. Rdirection
    19. Sball
    20. Tminute
    21. Uspeeds
    22. Vde
    23. Wnorthern
  2. 2drag bw wind and surface of the ocean, energy transfer bw the 2 is bw 3-[blank_start]4[blank_end]% (if strong [blank_start]wind[blank_end] blowing at the surface)
    Surface currents are deflected [blank_start]45[blank_end] deg to the [blank_start]right[blank_end] of wind direction in the N hemisphere
    [blank_start]Frictional[blank_end] couplings down the water column bw layers, until eventually the wind effects disappear, this depth depends on many things, including the fe[blank_start]tc[blank_end]h, duration, and s[blank_start]pee[blank_end]d
    Need prolong spell of wind and a [blank_start]long[blank_end] fetch
    Depth may only be 50-60 m , max depth is 200-[blank_start]3[blank_end]00 m for wind driven circulation.
    [blank_start]net[blank_end] flow or transport is perpendicular to the wind, [blank_start]90[blank_end] deg, ie towards the east in the [blank_start]southern[blank_end] hemisphere, if a southerly flowing wind net d[blank_start]eflection[blank_end] will be to the west.
    there is a depth at which the flow is 180 deg to the wind forcing or to surface flow. get a reversal of flow due to f[blank_start]rictiona[blank_end]l decoupling as u go down through the water column plus the deflection
    Ekman depth = depth at which the flow is [blank_start]reversed[blank_end], limit of the ekman spiral, after which the flow is dispersed, it depends on the coefficient of [blank_start]turbulent[blank_end] viscocity, and f which = [blank_start]corriolis[blank_end] effect.
    the [blank_start]coeficcient[blank_end] of turbulent viscocity = how good is the [blank_start]link[blank_end] bw the layers, constNT OF THE ocean, depends on temp, salin, de[blank_start]nsit[blank_end]y, constnat for the [blank_start]open[blank_end] ocean, thre s aturbulent component too, which has units of [blank_start]meters[blank_end] squared per secondThe Ekman depth Ed = √(2Av/f)
    Where Av is the coefficient of turbulent [blank_start]viscosity[blank_end] (m2/[blank_start]s[blank_end]).
    (varies from 20m – [blank_start]1[blank_end]50m, shallowest at [blank_start]poles[blank_end], deepest towards 0°)
    1. A4
    2. Bwind
    3. C45
    4. Dright
    5. EFrictional
    6. Ftc
    7. Gpee
    8. Hlong
    9. I3
    10. Jnet
    11. K90
    12. Lsouthern
    13. Meflection
    14. Nrictiona
    15. Oreversed
    16. Pturbulent
    17. Qcorriolis
    18. Rcoeficcient
    19. Slink
    20. Tnsit
    21. Uopen
    22. Vmeters
    23. Ws
    24. Xviscosity
    25. Y1
    26. Zpoles
  3. 3flows are described as where they are flowing [blank_start]to[blank_end],
    a wind is described as where it is flowing [blank_start]from[blank_end]
    so a northerly wind is from the [blank_start]north[blank_end], a northerly flow goes to the [blank_start]north[blank_end]
    upwelling in the Northern Hemisphere blows surface waters to the [blank_start]right[blank_end], dragging water away from the coast,
    offshore flow at the surface is replaced by [blank_start]colder[blank_end], (generally speaking its) [blank_start]nutrient[blank_end] rich water from deeper down.
    therefore high productivity at the [blank_start]surface[blank_end]
    this is why the sea is cold off Portugal and morocco and along the I[blank_start]beria[blank_end]n coast
    southerly wind = transport is on shore- blows wind onto coast, as [blank_start]water[blank_end] piles up it starts [blank_start]sinking[blank_end] and flows offshore, piling up warm but nutrient [blank_start]poor[blank_end] water against the coastline
    so v warm but [blank_start]low[blank_end] productivity
    drives it to the [blank_start]lower[blank_end] layers of coastal seas
    [blank_start]drags[blank_end] water away from the [blank_start]centre[blank_end], draws the main th[blank_start]ermoclin[blank_end]e up, in some cases it can break the surface, sometimes called ekman [blank_start]pumping[blank_end], creating a nutrient [blank_start]rich[blank_end] environment
    more commonly, if you look at the mean win patterns, tend to get [blank_start]anticyclonic[blank_end] winds, eg [blank_start]trade[blank_end] winds, westerlies etc eg the Indian ocean gyre, n and s pacific gyres, n Atlantic gyre, we get transport is to the right of the wind again, piling water up into the middle of it, getting surface [blank_start]convergence[blank_end], so d[blank_start]ownwellin[blank_end]g, dip in the th[blank_start]ermocline[blank_end], pushing it [blank_start]down[blank_end], surface convergence, nutrient [blank_start]poor[blank_end] centre of gyres, centre of [blank_start]sargasso[blank_end] sea, in the n Atlantic, only thing that lives there is the [blank_start]sargasso[blank_end] weed- bc it doesn’t need that much [blank_start]nutrients[blank_end],
    … pacific garbage patch- accumulates there- although wont actually fond a patch- has a 40% exit rate for every circulation
    southern hemisphere can tell bc a southerly wind is being deflected to the [blank_start]left[blank_end], causing upwelling, eg off the coast of Chile, and parts of peru
    (ekman transport is to the [blank_start]left[blank_end]- therefore giveaway it is the Southern hemisphere)
    1. Ato
    2. Bfrom
    3. Cnorth
    4. Dnorth
    5. Eright
    6. Fcolder
    7. Gnutrient
    8. Hsurface
    9. Iberia
    10. Jwater
    11. Ksinking
    12. Lpoor
    13. Mlow
    14. Nlower
    15. Ocentre
    16. Permoclin
    17. Qanticyclonic
    18. Rtrade
    19. Sconvergence
    20. Townwellin
    21. Uermocline
    22. Vdown
    23. Wpoor
    24. Xsargasso
    25. Ysargasso
    26. Znutrients
    27. AAleft
    28. ABleft
    29. ACpumping
    30. ADrich
    31. AEcyclonic winds drag
  4. 4Doldrums are at the [blank_start]equator[blank_end], Horse latitudes are at [blank_start]30[blank_end] deg n and s, polar systems are past [blank_start]60[blank_end] deg.
    get strong warming from mainly the [blank_start]ocean[blank_end] but also the [blank_start]land[blank_end] at the equator, creates an [blank_start]upwards[blank_end] moving airmass in terms of the ver[blank_start]tica[blank_end]l, in the atmospheric system, drives a rising air mass which moves towards the [blank_start]poles[blank_end], as it moves it starts to [blank_start]cool[blank_end] bc its high up, loosing moisture, it then falls.
    atmospheric gasses are composed of n2 and o2, most gasses occur in [blank_start]pairs[blank_end] of atoms, so have a higher molecular weight of [blank_start]H2O[blank_end]
    h2O has a lower molecular density than the above, so moist air has a [blank_start]lower[blank_end] density than dry air at the same pressure, so get a v rapid [blank_start]rise[blank_end] of warm moist air,
    so as moist warm air rises it expands bc less [blank_start]pressure[blank_end], it cools, water vapour condenses, (cools bc ad[blank_start]iabat[blank_end]ic effect) hence us getting v strong storms along the e[blank_start]quato[blank_end]r, as water vapour condenses to water droplets,
    falls at [blank_start]30[blank_end]deg n and s
    horse latitudes is sudden drop/downwelling of atmospheric masses towards the surface, relatively d[blank_start]r[blank_end]y at this point
    this is what drives hurricanes, rapid warming of [blank_start]surface[blank_end] layer, and evaporating rapidly, in the case of the Atlantic winds pushing air away from A[blank_start]frican[blank_end] coastline,
    causes rapid evaporation, bc d[blank_start]r[blank_end]y and w[blank_start]arm[blank_end], as air rises over several [blank_start]days[blank_end] it spins, so get a strong cyclone building up, as it moves across the ocean it picks up more [blank_start]heat[blank_end] energy and more moisture, bw 27 deg and 27.[blank_start]2[blank_end] deg, why you get it on the west not east side of the atlantic as they move across the ocean with the atmospheric s[blank_start]ystem[blank_end] they pick up the energy and moisture
    rely on moisture to drive them so don’t go over[blank_start]land[blank_end], even if just passing over a small land mass, eg Cuba, it will drop from a five to a four or three. It can then pick up again, eg if crosses the gulf of m[blank_start]exico[blank_end].
    key thing here is that winds are partly driven by the o[blank_start]ceans[blank_end], so is a two way thing
    1. Aequator
    2. B30
    3. C60
    4. Docean
    5. Eland
    6. Fupwards
    7. Gtica
    8. Hpoles
    9. Icool
    10. Jpairs
    11. KH2O
    12. Llower
    13. Mrise
    14. Npressure
    15. Oiabat
    16. Pquato
    17. Q30
    18. Rr
    19. Ssurface
    20. Tfrican
    21. Ur
    22. Varm
    23. Wdays
    24. Xheat
    25. Y2
    26. Zystem
    27. AAland
    28. ABexico
    29. ACceans
  5. 5chlorophyl has evolved to best to absorb peak of light at 4[blank_start]8[blank_end]5 nm ([blank_start]blue[blank_end] light), so
    algae look green bc its taken the blue out, as its absorbed, red light is taken out by the [blank_start]ocean[blank_end], so look at blue green ratios can v accurately measure levels.
    There are [blank_start]anticyclonic[blank_end] wind systems in north the N an S Atlantic, dragging water beneath them, at surface the drag is about [blank_start]45[blank_end] deg to the wind, pushing it towards the m[blank_start]iddle[blank_end] of the gyre. the net transport through 50, 150m to the right so piling [blank_start]water[blank_end] up in the midle, so the actual surface currents are dominated by the [blank_start]win[blank_end]ds,
    large dead areas, eg the [blank_start]sargasso[blank_end] sea and the south Atlantic gyre, same in the pacific, v [blank_start]low[blank_end] chlorophyl,
    pick up energy off c[blank_start]arriabean[blank_end], trade winds coming across and also Westerlies. top one is [blank_start]clock[blank_end]wise, ekman [blank_start]pumping[blank_end], piling water up in the middle, by iberia and n [blank_start]we[blank_end]st African coast is strong upwelling
    same past s africa and namibia, get, [blank_start]Ben[blank_end]guelas current particularly as we go up to the equator.
    equator appears to be quite productive- due to [blank_start]ekman[blank_end] transport,
    uneven distribution of land and sea bw n and s hemisphere therefore the meteorological [blank_start]equator[blank_end], along with the wind systems etc are shifted to the north, [blank_start]5[blank_end] deg n is the meteorological equator, MEANS south east tradewinds blow across the equator, gentle air stream blows at the meteorological equator
    south of the equator the wind is giving a weak net ekmans transport to the left of surface water,
    as the wind crosses the equator it switches to the [blank_start]right[blank_end] hand transport, so either side of equator is a [blank_start]div[blank_end]ergence, causes [blank_start]up[blank_end]welling along the equator,
    1. A8
    2. Bblue
    3. Cocean
    4. Danticyclonic
    5. E45
    6. Fiddle
    7. Gwater
    8. Hwin
    9. Isargasso
    10. Jlow
    11. Karriabean
    12. Lpumping
    13. Mclock
    14. Nwe
    15. OBen
    16. Pekman
    17. Qequator
    18. R5
    19. Sright
    20. Tdiv
    21. Uup
  6. 6El Nino - either a [blank_start]weakening[blank_end] or complete reversal of normal wather systems
    Normally: [blank_start]low[blank_end] pressure system over coast of [blank_start]Australia[blank_end], or at least Indonesia, [blank_start]high[blank_end] pressure system over south America, weak [blank_start]corriolis[blank_end] effect bc close to equator, so surface winds in a [blank_start]westerly[blank_end] direction,
    moist air [blank_start]rises[blank_end], its warm, so normally get lots of rain over indonesia, moderate over austalia, wamr water along [blank_start]wewst[blank_end] of pacific, [blank_start]upwelling[blank_end] in s american coast, in pacific- anchovies fisheries
    in an El Nino year the low pressure system shifts to the [blank_start]middle[blank_end] of the pacific, get a [blank_start]higher[blank_end] air pressure system over Indonesia. This changes the [blank_start]structure[blank_end] of the [blank_start]wind[blank_end] driven circulation of the pacific, it [blank_start]weakens[blank_end] the winds that blow up the coastline of S.America, and weakens the strength of the winds blowing offshore, so [blank_start]more[blank_end] of a downwelling scenario, at the least it just [blank_start]stops[blank_end] the upwelling,
    In Australia and Indonesia get some [blank_start]upwelling[blank_end], change the structure there,
    [blank_start]high[blank_end] pressure putting the low off or is the low bringing in high air- debated
    the warm seas along the coast of s America [blank_start]evaporate[blank_end] more readily, rapid rise in the amount of moisture going into the atm, doesn’t affect Peruvian coast, pushes it over the [blank_start]Andes[blank_end] into [blank_start]brazil[blank_end], meaning brazil gets [blank_start]flooded[blank_end] in el nino years
    decimates coffee crops and anchovies fisheries in s [blank_start]america[blank_end]
    in austrailia get forest fires, bush fires, [blank_start]drought[blank_end]
    this causes wobbles in the atlantic which propagates round the globe over periods of 1-[blank_start]2[blank_end] yrs,
    1. Aweakening
    2. Blow
    3. CAustralia
    4. Dhigh
    5. Ecorriolis
    6. Fwesterly
    7. Grises
    8. Hwest
    9. Iupwelling
    10. Jmiddle
    11. Khigher
    12. Lstructure
    13. Mwind
    14. Nweakens
    15. Omore
    16. Pstops
    17. Qupwelling.
    18. Rhigh.
    19. Sevaporate
    20. TAndes
    21. Ubrazil
    22. Vflooded
    23. Wamerica
    24. Xdrought
    25. Y2
    26. Z5
    27. AA3
    28. ABChile
    29. ACVenezuela
  7. 7Langmuir Circulation - [blank_start]local[blank_end] small scale effect, scales of [blank_start]meters[blank_end] - no effect of [blank_start]corriolis[blank_end] force
    circulation pattern is a series [blank_start]counter[blank_end]- rotating of 'helical' vortices in [blank_start]surface[blank_end] waters
    • alternating [blank_start]clockwise[blank_end] and counter-clockwise flow, short term, stop within [blank_start]minutes[blank_end] of wind stoping, to do with [blank_start]viscosity[blank_end], [blank_start]frictional[blank_end] forces of the water mass, the resistance of water to move, relatively [blank_start]shallow[blank_end], 4-[blank_start]6[blank_end] m, surface layer, wind rows are separated by 10-[blank_start]50[blank_end] m, so get zones of con and di vergence, stops within minutes of wind stopping, [blank_start]doesnt[blank_end] impact on ocean circulation or upwelling or nutrients, purley redistributing things like [blank_start]foam[blank_end] and rubbish,
    • results in surface [blank_start]convergence[blank_end] and divergence zones
    • surface manifestation of Langmuir convergence is foam lines [blank_start]parallel[blank_end] to the wind
    1. Alocal
    2. Bmeters
    3. Ccorriolis
    4. Dcounter
    5. Esurface
    6. Fclockwise
    7. Gminutes
    8. Hviscosity
    9. Ifrictional
    10. Jshallow
    11. K6
    12. L10
    13. M5
    14. N20
    15. O50
    16. P15
    17. Q25
    18. R30
    19. Sdoesn't
    20. Tdoes
    21. Ufoam
    22. Vconvergence
    23. Wparallel
    24. Xadjacent
    25. Yhorizontal

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Description
Degree Introduction to Oceanography Quiz on wind driven circulation- lecture?, created by Genie V on 19/04/2018.
Author
Genie V
Language
English
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