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EG1106 geographic information: a primer

EG1106 geographic information: a primer. Introduction to remote sensing 24 th November 2004. TOPICS. What is remote sensing? The electromagnetic spectrum Types of platform Satellite remote sensing in detail Proxy variables produced by RS Applications of remote sensing

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EG1106 geographic information: a primer

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  1. EG1106geographic information: a primer Introduction to remote sensing 24th November 2004

  2. TOPICS • What is remote sensing? • The electromagnetic spectrum • Types of platform • Satellite remote sensing in detail • Proxy variables produced by RS • Applications of remote sensing • Practical feedback today - reminder!

  3. What is Remote Sensing? A Definition: Remote sensing is the practice of deriving information about the earth’s land and water surfaces using images acquired from an overhead perspective, using electromagnetic radiation in one or more regions of the electromagnetic spectrum, reflected or emitted from the earth’s surface. Campbell, 1996

  4. What is Remote Sensing? Milestones in RS history: 1800: Discovery of infrared by Sir William Herschel 1839: Beginnings of photography 1850: Aerial photography using balloons 1909: Photography from aircraft 1972: Launch of Landsat 1970s - 1990s: Rapid development of digital image processing and launch of high resolution satellite sensors

  5. Physical Objects Sensor Data Extracted Information Applications Land use Geology Hydrology Vegetation Soils Human Health

  6. The electromagnetic spectrum • All objects above absolute zero (-273.15ºC or 0ºK) emit electromagnetic radiation • ER is produced by mechanisms such as: • Changes in energy levels of electrons • Acceleration of electrical charges • Radioactive decay • Thermal motion of atoms and molecules

  7. The electromagnetic spectrum • Nuclear reactions occur within the Sun which emits ER across a broad range of wavelengths called a spectrum • Some regions of this spectrum are visible (visible light) and some are invisible (infrared or ultraviolet) • Remote sensing relies on the measurement of this radiation

  8. Radiation from the Sun has a short wavelength (shortwave). Radiation from the Earth has a long wavelength (longwave)

  9. Types of platform • Aircraft • Satellite • Balloon • Rocket • Orbiting spacecraft • Most common is the satellite

  10. Satellite remote sensing in detail • Orbiting satellites have different strategies according to their purpose • Polar orbiters provide high resolution imagery for local studies • Geostationary satellites provide high temporal resolution for large area studies

  11. Satellite remote sensing in detail GEOSTATIONARY POLAR ORBITER Updates every hour updates twice a day Low spatial resolution High spatial resolution Used for weather prediction Used for monitoring Sees only portion of Earth Global coverage

  12. Geostationary Polar Orbiter

  13. Proxy variables produced by RS • RS produces continuous surface information (a raster layer within GIS) • Environmental variables may be derived from satellite information - but we call these proxies of the variable as they are only inferred from radiation measurements

  14. Proxy variables produced by RS • Temperature • from radiance measurements (TIR) • Rainfall • From Cold Cloud Duration (TIR) • Wind speed • From analysis of water vapour (WV) • Humidity • Tropospheric data (WV)

  15. Proxy variables produced by RS • Vegetation • NDVI (RED and NIR) • Albedo • Reflectance in visible region of ES

  16. AVHRR 29/11/01 13:39 < VIS IR >

  17. Meteosat: 29/11/2001 at 12:00z

  18. Aerial photograph: Liverpool docks area

  19. Landsat Thematic Mapper (TM): Liverpool

  20. Applications of RS • Environmental monitoring • Commercial agriculture • Petrochemical • Health • Hydrology and geology • Pollution monitoring • Climate change

  21. Practical Feedback Today Groups A2, B1 & B2 2 – 3:30pm Groups A1, C1 & C2 3:30 - 5pm NOTE: Bring ALL three pracs for marking & return Next week will be D1, D2, E1 & E2 ONLY These are the FINAL practical sessions for this term!!

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