Oceanography Ch6,7,8

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Oceanography Ch6,7,8
2012-02-21 07:46:32

OEAS ch 6,7,8
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  1. What gives water a number of unique properties:
    • 1. Water becomes less dense when it freezes
    • 2. Water has unusually high boiling and melting points
    • 3. Water has very high capacity, latent heat of fusion, and latent heat of vaporization
    • 4. Water is a powerful solvent
    • 5. Water conducts electricity
    • 6. Water is slightly compressible
  2. What is heat?
    energy produced by the random vibrations of atoms or molecules
  3. What is temperature?
    an object's response to input or removal of heat
  4. What is Heat Capacity?
    a measure of the heat required to raise the temperature of 1g of a substance by 1C.
  5. Temperature Profiles in the Ocean:
    • 1. Surface layers are heated in summer and cool in winter
    • 2. Since the surface is warmer than the water below, it is less dense and does not mix downward easily.
    • 3. This results in a thermocline, a verticle temperature gradient
    • 4. The permanent thermocline refers to the thermocline not affected by the seasonal and diurnal changes in the surface forcing
  6. Surface cooling leads to ________
  7. Surface cooling increases ___ of surface water. Which allows it to _____.
    density; mix
  8. Surface water is no longer "stable", when it is cool, so it ____ due to buoyancy.
  9. Specific heat of Water:
    The specific heat is the amount of heat per unit mass required to raise the temperature by one degree Celsius.
  10. Qs:
    • Qs: Energy from sun
    • Qb: Longwave Radiation (blackbody radiation)
    • Qe: Latent heat (loss of heat for evap/gain of heat for condensation)
    • Qh: Sensible heat flux (air-sea temperature difference)
  11. Why is the Ocean Salty?
    • -Input by river water
    • -Dissolved gases lead to chemical weathering of continental rocks
  12. How are materials being put into the ocean?
    How are materials removed from the water?
    • Into: through river discharge, precipitation and hydrothermal activity
    • Removed: through sedimentation and biologic activity
  13. What is Residence time?
    Amount of element in the ocean/ rate at which the element is aded to the ocean
  14. What is mixing time?
    Time it takes for a substance to become uniformly distributed.
  15. Materials in the ocean will behave conservatively when?
    What will this maintain?
    When the residence time is much longer than the mixing time of the ocean. Will maintain constant proportionality.
  16. Short residence times lead to _____ behavior.
  17. Conductivity is a function of ____, ____, and _____.
    To measure salinity, you must measure C_____, T____ and D_____ (CTD).
    • temperature, salinity, pressure.
    • Conductivity, Temperature, Depth
  18. CTD is used for?
    primary tool for determining essential physical properties of sea water
  19. Adiabatic Temperature Changes:

    Adiabatic temperature changes occur because of the _____.
    changes in temperature that occur independently of any transfer of heat to or from the surrounding environment.

    compressibility of fluids
  20. Explain an example of Adiabatic temperature.
    • 1. As air rises, there is lower pressure so then it expands.
    • 2. The same # of molecules are now moving around in a much bigger volume. So this creates less energy
    • 3. The temp. falls even though no heat has been removed from the volume.
  21. Potential Temperature:
    the temperature a fluid would attain if brought adiabaticaly to a pressue of 1000 millibars
  22. Pycnocline can be a _____ and a ____.
    thermocline and halocline
  23. Any region of strong density gradient is called a _______.
  24. Surface mixed layer is seperated from dense deep layer by temperature is called?
  25. Surface mixed layer is seperated from dense deep layer by salinity is called?
  26. If water is denser than its surroundings there is a ______ buoyant force.
  27. If water is less dense than its surroundings there is a ______ buoyant force.
  28. In _____ flow, instabilities grow and then collapse, resulting in ____ mixing.
    turbulent, irreversible
  29. When will turbulence develop?

    Turbulence likely: Ri ? 0.25
    No active turbulence: Ri ? 0.25
    when instabilities in the flow driven by shear are greater than the stabilizing force of buoyancy.

    • Turbulence likely: Ri < 0.25
    • No active turbulence: Ri > 0.25
  30. Flow can either be Laminar or turbulent:
    What happens when there is a
    Low Re=?
    High Re=?

    Which is more effective at mixing? Turbulent diffusion or molecular diffusion
    • Low Re = Laminar Flow
    • High Re= Turbulent

    • Turbulent diffusion because salt coefficient is much greater.
    • Laminar flow does not result in any turbulent mixing, only molecular diffusion.
  31. Why is stratification and turbulence important?
    If there is no turbulence due to stratification, the exchange across the pycnocline will be very slow....where there is only molecular diffusion.
  33. The Continuity Equation states that a divergence or convergence of the flow in one direction must be _____ for by a _______ or ______ in one or both of the other directions so that the combined effects sums to ____.

    du + dv + dw = 0
    dx + dy + dz
    compensated; convergence or divergence; zero
  34. Review slide 7 in Ch7
  35. Newton's Second Law?
    • Force equals mass times acceleration
    • F=ma
    • F = force (kg m/s2)
    • m= mass (kg)
    • a= acceleration (m/s2)
  36. When objects move through viscous medum like air or water, the medium exerts a _____ that ____ the motion of the object relative to the medium.
    drag force, opposes
  37. What forces may cause motion in the ocean?
    • 1) Wind
    • 2) Atmospheric pressure
    • 3) Gravitation due to Earth, Moon, and Sun (tides)
    • 4) Seismic activity (tsunamis)
  38. Due to the _______ objects in the Northern Hemisphere appear to ______. In the Southern Hemisphere, objects appear to ________.
    Coriolis "force"; veer to the right; veer to the left
  39. 1) Distance covered by equator is much ____ than that cover near the ______, so the apparent speed of rotation is much higher at the ________.

    2) Moving off the equator always results in entering a region with ____ apparent speed of rotation.

    3) As a result the Coriolis frequency is only ____ for motion along the equat or.
    • 1) bigger; poles; equator
    • 2) slower
    • 3) zero
  40. ____- momentum equation :

    du = Pressure Gradient + coriolis - friction
    X- momentum equation
  41. ____- momentum equation :
    dv = Pressure Gradient + coriolis - friction
  42. ____- momentum equation :
    dw = Pressure Gradient

    Where is Friction and Coriolis?

    Friction and Coriolis are much smaller in the vertical direction and can be ignored.
  43. Hydrostatic:
    Water at rest but, even when water is not at rest the _____ can be neglected. This is called?

    This is called hydrostatic approximation
  44. Barotropic Pressure Gradient is....
    A pressure gradient that is caused by differences in sea surface height
  45. Baroclinic Pressure Gradient is...
    A pressure gradient that is caused by density difference.
  46. In a ____ flow momentum is exchange between fast and slow moving water by ______.
    turbulent; turbulent eddies
  47. Horizontal Momentum Equation:

    du- fv = dP + d K du
    dt dx dz dz
    • du/dt = acceleration
    • -fv = coriolis
    • dP/dx = Pressure Gradient
    • d/z K du/dz = friction
  48. Flux of momentum is a stress at the surface is called?
    the surface stress or wind stress
  49. consider the balance of forces acting on the surface of the water when wind blows.
    What happens to the ocean?
    t= T1; wind begins to blow toward the north?
    t= T2; wind continues to blow?
    • t=0 no wing, no motion
    • t=T1 imbalance between wind stress and friction drag cause flow to accelerate
    • t=T2 friction increases to balance wind stress, no more acceleration
  50. Wind stress acts to _____ the parcel ro the _____.
    Friction drag always acts ______ of the direction of motion.
    Coriois always acts to ______ of motion.
    • accelerate; north
    • opposite
    • right
  51. Result of all forces in balance due to deflection to the ____ is _____ to the ___ of the wind.
    right; 45 degrees; right
  52. Ekman Spiral:
    1. The top layer is driven forward by the wind and each layer below is moved by friction (momentum flux)

    • 2. Each layer gets slower than the overlying layer.
    • 3. Each layer gets momentum from the layer above, just like how the wind giving momentum to the surface layer.
  53. The _____ and the ___ are the two winds that drive the ocean's currents.

    ____ is near the poles
    ____ is near the equator.
    westerlies; trade winds

    • Westerlies
    • Trade winds
  54. % of water in ocean;
    Surface zone:
    Deep zone:
    • Surface zone:2% water
    • Deep zone: 80% water
    • Pycnocline: 18% water
  55. About ___% of the water in the world ocean is involved in ______, water flowing horizontally in the uppermost 400 meters of the ocean's surface, driven mainly by _____.
    10%; surface currents; wind friction
  56. Gyres are formed by a combination of?
    surface winds, sun's heat, the coriolis effect and gravity
  57. The Northern Hemisphere's gyre circulates _______.
    The Southern Hemi circulates _______.
    • clockwise
    • counter- clockwise
  58. The flow around a gyre is approximately in _____ Balance.
  59. Pressure Gradient in x-direction is ______ by rotation acting on the flow in the _____.
    • "balanced"
    • y-direction
  60. Geostrophic gyres:

    Of the six great currents how many are geostrophic gyres?
    are gyres in balanc between the pressure gradient and the Coriolis effect.

  61. Western boundary currents:
    Eastern boundary currents:
    West: these are narrow, deep, fast currents found in the western boundaries of ocean basins.

    East: These currents are cold, shallow and broad....boundaries are not well defined.
  62. Why are Western Boundary Currents Intensified?

    Hints: Coriolis
    1. coriolis force varies with latitude. It is stronger near the poles.

    2. As a result, the northern portion of the gyre turns south muh sooner than the souther portion turns north.

    • 3. so the center of the pile of water in the middle of the gyre is offset to the west. this results in a stronger pressure gradient on the west side of basin.
    • 4. Strength of a geostrophic current is directly proportional to the pressure gradient.
  63. Upwelling:
    Up: upward motion of water caused by surface divergence. brings cold, nutrient rich water to the surface.

    Down: downward motion of water caused by surface convergence. Supplies the deeper ocean with dissolved gases.
  64. What leads to upwelling and downwelling?
    Rotation and wind driven circulation which leads to convergence or divergence.....which results in verticle velocity.
  65. Coastal upwelling:
    In the northern hemisphere, coastal upwelling can be caused by winds from the north blowing along the west coast of a continent. Water that is moved offshore due to Ekman transport is replaced by cold, deep, nutrient-rich water.
  66. Coastal Downwelling:
    Wind blowing from the south along a Northern Hemisphere west coast for a prolonged period can result in downwelling. These areas are low in nutrients.
  67. Coastal Upwelling leads to _____ biological productivity.
  68. Gap winds lead to strong upwelling?
  69. The largest surface currents are organized into huge circuits called?
  70. Gyres are in _____ balance.
    geostrophic balance
  71. Geostrophic balance is...
    the balance between Pressure Gradient and coriolis force.
  72. The pressure gradient results from water that piles up in the center of a gyre due to _______ by ___ transport.
    convergence; ekman transport
  73. Currents on the western boundaries of gyres are deeper and faster.
  74. Upwelling and Downwelling describe the ____ movements of water masses.