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IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

Lecture 1 The basic concepts of oceanography. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography. Oceanography is a multi-discipline science studying the World ocean. It includes: Physical oceanography Marine geology Marine chemistry Marine biology

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IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

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  1. Lecture 1 The basic concepts of oceanography IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  2. Oceanography is a multi-discipline science studying the World ocean. • It includes: • Physical oceanography • Marine geology • Marine chemistry • Marine biology • Marine technology • etc. In this course, we restrict our study to the topics that include instruments, measuring ocean properties and mounted on earth-orbiting satellites. As such, we do not touch the problems of marine geology and chemistry, because satellite sensors cannot help much in these studies. Most satellite observations of the ocean are related to physical oceanography. Another topic of satellite oceanography is the measurements of ocean color, which can be used as assessments of phytoplankton biomass and are of great interest to marine biologists. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  3. The basic topic of physical oceanography is ocean circulation. This image of MODIS satellite illustrates a plume of polluted water discharged after rainstorm from the mouth of Santa Clara River and transported by coastal current to Santa Monica Bay. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  4. 1. What drives ocean currents? Two external forces influence the World Ocean generating ocean currents -gravitationandthe energy flux from the sun. Gravitation includestidal forcesresulting from the interaction of water mass with the moon and the sun, androtation of the Earth. The radiation flux from the sun results inwind stress, heating and coolingof the ocean surface, andevaporation and precipitationof water. A complex process of interaction between these forces results in a complex and variable pattern of ocean circulation. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  5. 1. What drives ocean currents? Solar heating is different at different latitudes, because equal amounts of sunlight are spread over a greater surface area near the poles than in the tropics. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  6. 1. What drives ocean currents? The amount of solar energy also varies with time, resulting from the annual rotation of the earth around the sun on an axis tilted by 23º27’ and earth diurnal rotation. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  7. 1. What drives ocean currents? Warm air rises and cool air sinks; a convection current forms in a room resulting from uneven heating and cooling. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  8. 1. What drives ocean currents? The amount of heat radiation is of maximum at the equator. The cold air at the poles is denser than the warm air at the equator; hence, air pressure at sea level is higher at the poles than at the equator. In other words, the pressure gradient at sea level is directed from the poles toward the equator, and the pressure gradient in the upper part of the atmosphere has the opposite sign. In fluid and gases pressure gradients produce flow from regions of high pressure to regions of low pressure. If the earth were not rotating, the response to these pressure gradients would be direct and simple. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  9. 1. What drives ocean currents? At the higher latitude each location travels a shorter path on the rotating Earth than at the equator. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  10. 1. What drives ocean currents? A cannonball shot north from the cannon located at the equator is also moving east at the speed of the Earth rotation at the equator and veers to the right from its northward path. A cannonball shot south travels over portions of the Earth that are moving increasingly faster in an eastward direction and also veers to the right. This effect is called “Coriolis effect”. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  11. 1. What drives ocean currents? The rotation of the Earth modifies the pattern of atmospheric circulation. As air moves toward the equator, the rotation of the earth shifts ocean and land eastward under it. The result is "easterly" winds (Polar Easterlies and Trade winds). Traveling from the equator to the pole air in the upper atmospheric layer cools. About 30ºN and 30ºS the air becomes dense enough to fall back to earth surface, forming two Hadley cells of atmospheric circulation. Similar cells are created between the poles and 60º latitude. The zones between 30º and 60º are called Ferrel cells, where "westerly" winds dominate. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  12. 1. What drives the ocean currents? Atmospheric circulation pattern is modulated by the difference between the heat balance over land and sea zones. During summer land accepts more heat and onshore wind dominates. During winter land is cooler than sea and offshore wind dominates. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  13. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  14. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  15. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  16. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  17. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  18. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  19. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  20. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  21. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  22. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  23. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  24. 1. What drives ocean currents? Surface winds over the World Ocean IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  25. 1. What drives the ocean currents? 1.2. Wind stress Wind stress t (kg m-1 s-2 or Newton per m2) is an important quantity in the process of wind driving ocean currents. |t | = Cd raU2, where Cd  is the dimensionless "drag coefficient" (about 0.0013), ra  is air density (about 1.2 kg m-2), U  is wind speed at 10 m above sea level (m s-1). IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  26. 1. What drives the ocean currents? Wind stress is a square function of wind speed because the wind forcing depends on wind speed and sea roughness, which in turn depends on wind speed. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  27. 1. What drives ocean currents? Horizontal circulation - Ekman drift The movement of water as influenced by the Coriolis effect and gravity. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  28. 1. What drives ocean currents? Horizontal circulation - Ekman drift The Ekman spiral. The top layer is driven forward be the wind, and each layer below is moved by friction. Each succeeding layer moves at a slower speed and at an angle to the layer above. The theoretical average direction of water flow is 90° to the right in the Northern Hemisphere. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  29. 1. What drives ocean currents? Horizontal circulation - Ekman drift The current moves at an angle to the wind (to right in the Northern Hemisphere), turning further away from the wind direction and becoming weaker with depth. Therefore, the wind-driven component of water transport is directed perpendicular to the mean wind stress to the right in the Northern Hemisphere. The magnitude (kg m-1 s-1) is |Me| = |t / f |,where t is wind stress and f is Coriolis force. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  30. 2. The heat flux through the ocean surface The heat flux is determined by the balance between four components: - incoming solar radiation; - outgoing back radiation; - heat loss from evaporation; - mechanical heat transfer between the ocean and the atmosphere. The three last components directly depend on sea surface temperature (SST), a basic ocean property measured from satellites. IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  31. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. January 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  32. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. February 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  33. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. March 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  34. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. April 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  35. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. May 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  36. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. June 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  37. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. July 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  38. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. August 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  39. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. September 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  40. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. October 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  41. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. November 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  42. 2. The heat flux through the ocean surface Solar radiation (W m-2) received at sea level. December 1985 IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  43. 2. The heat flux through the ocean surface depends on solar radiation and sea surface temperature incoming solar radiation incoming solar radiation outgoing back radiation IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  44. 2. The heat flux through the ocean surface January IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  45. 2. The heat flux through the ocean surface February IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  46. 2. The heat flux through the ocean surface March IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  47. 2. The heat flux through the ocean surface April IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  48. 2. The heat flux through the ocean surface May IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  49. 2. The heat flux through the ocean surface June IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

  50. 2. The heat flux through the ocean surface July IoE 184 - The Basics of Satellite Oceanography. 1. The Basic Concepts of Oceanography

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