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					GEF2610 Physical Oceanography
                        Course content
The physical structure and circulations of the oceans, and the
physical processes influencing them.


                       Learning outcomes
The students shall have knowledge about the physical properties of
ocean waters, understand concepts like stability and potential
density, and be able to describe the energy exchange with the
atmosphere. They shall know how the standard instruments are
functioning and understand the meaning of observations presented
in a T-S diagram. The students shall have a good overview of the
general oceanic circulation, understand the driving forces and
mechanisms behind the different types of circulation, and know
where in the world oceans bottom water is formed and where
upwelling occurs.
•   Ocean dimensions and extensions
•   Physical properties of ocean water
•   Chemical components of ocean water
•   Standard instruments
•   Forces; Equation of Motion
•   Energy exchange with the atmosphere
•   Physical structure of the oceans
•   General oceanic circulation
•   Waves
•   Tides
Ocean dimensions and extensions


 • Names of the different oceans
 • Topography of the different oceans
Sand waves
Relative dimensions of atmosphere
            and oceans
Physical properties of ocean waters
     •   Temperature, salinity, density
     •   Compressibility
     •   Potential temperature and density
     •   Freezing point
     •   Specific heat (heat capacity)
     •   Latent heat of evaporation
     •   Latent heat of freezing
     •   Optical properties
     •   Acoustical properties
Translational motion in gases
Light in the sea

Snell’s Law of Refraction
          4
   sin i  sin j
          3

  Vertical attenuation

   E ( z )  E0 e   K z
Fig. 3.9 Optical pathways to an ocean color sensor
              (from Robinson, 1983).
Fig. 3.10 Global chlorophyll concentration in mg/m3 for the
    ocean and Normalized Difference Vegetation Index
   (-1 to +1) for the land surface for Sept. 97 – Aug. 98.
Sound in the sea
 Snell’s Law of Refraction

    sin i sin j
         
     vi    vj
   Spherical attenuation
               2
             R c ( R  R )
 ( R )  0   0
               e
               2
                           0


             R
Chemical composition of ocean
           water


  •   Principal constituents
  •   Constant relative composition of seawater
  •   Gases in seawater (O2)
  •   Methods for determination of salinity
  •   Methods for determination of density
    Standard instruments
•   Reversing thermometers
•   Water samplers (e.g. NIO bottles)
•   ST electronic bridges
•   CTD sensors
•   Irradiance meters
•   Secchi disk
•   Echo sounders
•   Current meters
 Equation of Motion
     
a b c  F  g T
    Simplified models
   •Hydrostatic equilibrium
   •Geostrophic current
   •Ekman spiral
   •Equilibrium tide
 Hydrostatic equilibrium –
   hydrostatic pressure
             
          0bg

          h

p (h)  g   ( z ) dz  p (0)  g  h
          0
Geostrophic current
        
  0  b c  g

     g
  v  tan( )
     f
Ocean dynamic topography
Tuva
Ekman spiral – wind current

          
       0cF
Wind speed
Equilibrium tide


       
 0  b  g T
     Energy exchange with the
           atmosphere


• Kinetic energy (currents, waves)
• Radiative energy (shortwave, longwave)
• Heat exchange (latent heat of evaporation,
  latent heat of freezing, heat conduction)
         Budgets


•   Heat budgets
•   Volume budgets
•   Salt budgets
•   Knudsen’s Relations
   General oceanic circulation
• Surface currents
• Interaction between atmospheric wind and
  pressure systems and the major oceanic gyres
• Estuarine circulation
• Upwelling
• El Niño (ENSO)
• Thermohaline circulation
• Vertical convection
• Bottom and deep-water formation
Polarfront
          Estuaries


•   Estuaries
•   Fjords
•   Estuarine circulation
•   Deep water exchange in fjords
Front: brackish water / sea water
                          Gåsøyrenna: T and S 04.04.2008

                                    salinity
             0   5   10        15              20   25     30   35
         0




        10




        20




        30
                                                                     S-Gaasoy
Depth




                                                                     S-Gaasoy-feb
                                                                     T-Gaasoy
                                                                     T-Gaasoy-feb
        40




        50




        60




        70
                            Gåsøyrenna: Density 04.04.2008


                                 Density - 1000
             19   20   21      22            23              24   25   26
         0




        10




        20




        30
Depth




                                                                            Gaasoy
                                                                            Gaasoy-feb

        40




        50




        60




        70
 Global distribution of temperature,
        salinity, and density

• Relationship between temperature,
  salinity and the large-scale pressure and
  wind systems at the surface
• Typical vertical profiles at low, middle and
  high latitudes
Waves
               Wind waves
     Significant wave height :
     the average height of the highest
     third of the waves.

  Wave height depends on:
• speed (the force of the wind);
• duration (the time the wind has been blowing);
• fetch (the length of the area the wind is blowing
  over).
Wave height definition for a regular
             wave
Wave height definition for an
   irregular sea surface
Histogram of wave heights
Wave speed (phase velocity)
• Short waves (deep water waves)

          1.25m 0.5 s 1  L  1.56 m s 2 T
      gL
 c
      2

• Long waves (shallow water waves)
  including tsunamies and tides

        c     g h  3.15m     0.5
                                      s   1
                                                  h
Wave height
Storm
Typhoon Wipha
Earth – Moon Orbit
                Tides




• Equilibrium tide (spring and neap tide,
  diurnal inequality)
• Real tides in the ocean
M2 amplitude
Bay of Fundy; High Tide
Bay of Fundy; Low Tide
         Saltstraumen;
mean speed 4-5 m/s, max speed 10 m/s?
    Ice in the sea

•   Slush, grease ice
•   Pancake ice
•   Pack ice
•   Hummocs
•   Icebergs
Grease and pancake ice
Pancake ice
Pack ice
Iceberg
Iceberg
GLACIER

				
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