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Observing Climate - Remote Sensing

Observing Climate - Remote Sensing. Science Concepts Definition. Remote Sensing Observations Fundamental Principle Satellite Remote Sensing Components Types of Sensing Passive Sensing Active Sensing Fundamental Properties Radiometric Resolution Spectral Resolution

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Observing Climate - Remote Sensing

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  1. Observing Climate - Remote Sensing Science Concepts Definition Remote Sensing Observations Fundamental Principle Satellite Remote Sensing Components Types of Sensing Passive Sensing Active Sensing Fundamental Properties Radiometric Resolution Spectral Resolution Spatial Resolution

  2. Observing Climate - Remote Sensing View NOVA Mayan Movie

  3. Observing Climate - Remote Sensing Definition Science and art of obtaining information about an object, area or phenomenon through an analysis of data acquired by a device that is not in direct contact with the area, object or phenomenon under investigation Lillesand, Thomas M., and Ralph W. Kiefer, 1979, Remote Sensing and Image Interpretation, John Wiley and Sons, Inc., p. 1 What are some common examples of remote sensors?

  4. Observing Climate - Remote Sensing Galileo History • Telescope invented by spectical-maker Hans Lippershey (c1570-c1619) of Holland • Galileo introduced the telescope to astronomy in 1609 - Limited magnification - up to 30 times - and a narrow field of view - First to see the craters of the moon, discover sunspots, the four large moons of Jupiter, and the rings of Saturn http://www-groups.dcs. st-and.ac.uk/ ~history/Posters2/ Galileo.html

  5. Observing Climate - Remote Sensing History (Con’t) • 1858 — First aerial (balloon) photographer Gaspard Felix Tournachon, also known as Nadar; picture of Paris • 1903 — The Bavarian Pigeon Corps http://www. skyeyephotography. com/history.htm http://latteier.com/pigeoncam/ San Francisco from a kite, 1906 http://latteier.com/pigeoncam/ http://latteier.com/pigeoncam/

  6. Observing Climate - Remote Sensing History (Con’t) • 1908 — First photos from an airplane First flight, Wright Bros., Dec. 1903 • 1909 — Dresden International Photographic Exhibition • 1914-1918 — World War I

  7. Observing Climate - Remote Sensing History (Con’t) • Today — Many platforms - Ground based - Aircraft - Space shuttle - Satellite

  8. Observing Climate - Remote Sensing Fundamental Principle • Targets display discernible differences in emitted, reflected or transmitted energy - Target appearance changes with the wavelength with which it is observed - Dissimilar targets have differing appearances in a single wavelength (or band of wavelengths) Data Types • Photographic - Record one frame at a time on a physical medium • Digital - Record brightness (intensity) and convert to digital value one pixel at a time • Pixels - Picture elements

  9. Observing Climate - Remote Sensing Satellite Remote Sensing Components • Source of illumination • Atmosphere • Target • Sensing system • Data processing and analysis system • Output product Two Types of Sensing Systems • Passive • Active

  10. Observing Climate - Remote Sensing Passive Sensing • Satellite measures energy that is reflected, emitted or transmitted (i.e., not absorbed or reflected) from the object, i.e., after the radiation has interacted with the object - Human eye - Camera - Radiometer • Passive scanning geometry measuring Earth’s emitted radiation • Passive scanning geometry measuring Earth’s reflected solar radiation Image Output Sensor Transmitted Scattered Atmosphere Absorbed Processing & Analysis Source of Illumination and Target Sensor Target Source of Illumination

  11. Observing Climate - Remote Sensing Passive Sensing (Con’t) • Passive limb scanning geometry measuring atmosphere’s transmitted (not absorbed or reflected solar radiation Source of Illumination Sensing System Sun Target Atmosphere

  12. Observing Climate - Remote Sensing Active Sensing • Satellite emits energy and then measures return energy after the radiation has interacted with the Earth’s surface or atmosphere. - Radar - Sonar - Laser Sensor Image Output Reflected Energy Transmitted Energy Atmosphere Processing & Analysis Target

  13. Observing Climate - Remote Sensing Four Fundamental Properties For Design • Image depends on the wavelength response of the sensing instrument (radiometric and spectral resolution) and the emission or reflection spectra of the target (the signal). - Radiometric resolution - Spectral resolution • Image depends on the size of objects (spatial resolution) that can be discerned - Spatial resolution • Knowledge of the changes in the target depends on how often (temporal resolution) the target is observed - Temporal resolution

  14. Observing Climate - Remote Sensing Radiometric Resolution • Number of shades or brightness levels at a given wavelength • Smallest change in intensity level that can be detected by the sensing system

  15. 0.4 mm 0.7 mm Black & White Images Blue + Green + Red Observing Climate - Remote Sensing Spectral Resolution • Example: Black and white image - Single sensing device - Intensity is sum of intensity of all visible wavelengths Can you tell the color of the platform top? How about her sash?

  16. 0.4 mm 0.7 mm Color Images BlueGreenRed Observing Climate - Remote Sensing Spectral Resolution (Con’t) • Example: Color image - Color images need least three sensing devices, e.g., red, green, and blue; RGB Using increased spectral resolution (three sensing wavelengths) adds information In this case by “sensing” RGB can combine to get full color rendition

  17. Observing Climate - Remote Sensing Spectral Resolution (Con’t) • Example - What do you believe the image would look like if you used a blue only sensitive film? - What do you believe the image would look like if you used a green only sensitive film? - What do you believe the image would look like if you used a red only sensitive film?

  18. Observing Climate - Remote Sensing Spectral Resolution (Con’t) • Example (Con’t) - Blue only sensitive film - Green only sensitive film - Red only sensitive film

  19. Observing Climate - Remote Sensing Spectral Resolution (Con’t) • Example (Con’t) - What do you believe the image would look like if you used a thermal infrared sensitive film? Blinded in the darkness, he extended his arms, felt around for obstacles, both to avoid and to hide behind. The men wearing infrared monocular night-vision units, the lenses strapped against their eyes by means of a head harness and helmet mount, were doubtless also carrying handguns. The others had rifles fitted with advanced infrared weapon sights. Both allowed the user to see in total darkness by detecting the differentials in thermal patterns given off by animate and inanimate objects. Ludlum, Robert, 2000: The Prometheus Deception, p. 96.

  20. Observing Climate - Remote Sensing Spectral Resolution (Con’t) • Example (Con’t) - What do you believe the image would look like if you used a thermal infrared sensitive film?

  21. Heat - Energy Transfer (Con’t) What do you see if you look in the thermal infrared wavelength, i.e., around 10 microns? Visible range from 0.4 to 0.7 microns Infrared range around 10 microns

  22. Observing Climate - Remote Sensing Spectral Resolution (Con’t) • Example - Thermal infrared view Note warmer objects are brighter

  23. Observing Climate - Remote Sensing Spectral Resolution (Con’t) • Example - What do you believe the image would look like if you used near and middle infrared sensitive film? Near and middle infrared wavelengths, wavelengths between the visible and the thermal infrared (~10 microns) http://observe.arc.nasa.gov/nasa/education/reference/reflect/ir.html

  24. Observing Climate - Remote Sensing Spectral Resolution (Con’t) • Example - What do you believe the image would look like if you used near and middle infrared sensitive film?

  25. Observing Climate - Remote Sensing Spectral Resolution (Con’t) • Spectral response depends on target • Leaves reflect green and near IR • Water reflects at lower end of visible range

  26. Observing Climate - Remote Sensing Spectral Resolution (Con’t) • Example of sampling wavelengths

  27. Observing Climate - Remote Sensing Spatial Resolution • 40 X 40

  28. Observing Climate - Remote Sensing Spatial Resolution (Con’t) • 80 X 80

  29. Observing Climate - Remote Sensing Spatial Resolution (Con’t) • 320 X 320 Image depends both on spatial resolution and on radiometric resolution of the optical instrument

  30. Observing Climate - Remote Sensing Spatial Resolution (Con’t) • GOES sounder – temporal resolution every hour; spatial resolution (10 km) • MODIS instrument on the polar orbiting platforms - up to four passes a day, two daytime and two nighttime; spatial resolution (1 km) GOES LST 2 AM CST AQUA MODIS 24 JAN 2004

  31. Observing Climate - Remote Sensing Spatial Resolution (Con’t) • In addition, MODIS observes 36 separate frequencies of radiation, ranging from visible to infrared. GOES detects only five frequencies. http://science.nasa.gov/headlines/y2004/09jan_sport.htm

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