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GEF2610 Physical Oceanography

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

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GEF2610 Physical Oceanography

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  1. 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.

  2. 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

  3. Ocean dimensions and extensions • Names of the different oceans • Topography of the different oceans

  4. Sand waves

  5. Relative dimensions of atmosphere and oceans

  6. 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

  7. Translational motion in gases

  8. Light in the sea Snell’s Law of Refraction Vertical attenuation

  9. Fig. 3.9 Optical pathways to an ocean color sensor (from Robinson, 1983).

  10. 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.

  11. Sound in the sea Snell’s Law of Refraction Spherical attenuation

  12. 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

  13. Standard instruments • Reversing thermometers • Water samplers (e.g. NIO bottles) • ST electronic bridges • CTD sensors • Irradiance meters • Secchi disk • Echo sounders • Current meters

  14. Equation of Motion • Simplified models • Hydrostatic equilibrium • Geostrophic current • Ekman spiral • Equilibrium tide

  15. Hydrostatic equilibrium – hydrostatic pressure

  16. Geostrophic current

  17. Ocean dynamic topography

  18. Tuva

  19. Ekman spiral – wind current

  20. Wind speed

  21. Equilibrium tide

  22. 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)

  23. Budgets • Heat budgets • Volume budgets • Salt budgets • Knudsen’s Relations

  24. 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

  25. Polarfront

  26. Estuaries • Estuaries • Fjords • Estuarine circulation • Deep water exchange in fjords

  27. Front: brackish water / sea water

  28. 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

  29. Waves

  30. 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).

  31. Wave height definition for a regular wave

  32. Wave height definition for an irregular sea surface

  33. Histogram of wave heights

  34. Wave speed (phase velocity) • Short waves (deep water waves) • Long waves (shallow water waves) including tsunamies and tides

  35. Wave height

  36. Storm

  37. Typhoon Wipha

  38. Earth – Moon Orbit

  39. Tides • Equilibrium tide (spring and neap tide, diurnal inequality) • Real tides in the ocean

  40. M2 amplitude

  41. Bay of Fundy; High Tide

  42. Bay of Fundy; Low Tide

  43. Saltstraumen; mean speed 4-5 m/s, max speed 10 m/s?

  44. Ice in the sea • Slush, grease ice • Pancake ice • Pack ice • Hummocs • Icebergs

  45. Grease and pancake ice

  46. Pancake ice

  47. Pack ice

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