What is remote sensing

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What is remote sensing?
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Collection of information about an object without
being in direct contact with the object
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Medical examples
Cat-scans
X-rays
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A photograph
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An aerial photograph
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A satellite image
Lake Erie
Downtown Cleveland
Cleveland International Airport

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Highest resolution data available to the public
QuickBird 0.61m pixel
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Before we could fly
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How do imaging satellites work?
Satellite sensors see reflected and emitted
radiation
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Principles of remote sensing

• Energy is detected by a sensor
• All sensors are sensitive to specific areas of
  the electromagnetic spectrum
• The spectrum consists of electromagnetic
  radiation that occurs in various wavelengths
• Areas of the electromagnetic spectrum can be
  sensed bands
• Broad bands
• Narrow bands

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THE ELECTROMAGNETIC SPECTRUM
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The spectrum of visible light

• Violet 0.4 - 0.446 mm
• Blue 0.446 - 0.500 mm
• Green 0.500 - 0.578 mm
• Yellow 0.578 - 0.592 mm
• Orange 0.592 - 0.620 mm
• Red 0.620 - 0.7 mm

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Whats so special about satellite imagery?
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Satellites

• Satellites are man-made vehicles that orbit the
  earth and possess sensors that detect energy that
  is emitted from the Earth
• Geostationary satellites
• Orbit at 35,784 km above the Earths surface with
  an orbit time of 23 hours, 56 minutes, and 4
  seconds
• Includes TV satellites, communications
  satellites, and some weather satellites
• Low Earth Orbit (LEO) satellites
• Orbit at lower altitudes typically between 700
  km and 3,000 km
• Includes GPS satellites, pole to pole orbiting
  satellites

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Geostationary satellites

• Move in-sync with the Earths movements
• TV satellites
• Weather satellites

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Low Earth Orbit Satellites

• Includes pole to pole orbiting satellites
• Earth spins under the orbiting satellite
• Satellites typically sun-synchronous
• Orbit southward in daylight
• Illuminated zone of Earth

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Satellites discussed at this institute are all
LEO satellites

• Landsat 30 m 8 bands
• MODIS 1 km 36 bands
• SeaWifs 1.1 km 8 bands
• Topex/Poseidon 50 km satellite altimeter
• AVHRR 1.1 km 5 bands

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How do satellites collect data?
Along-track scanners
Across-track scanners whiskbroom
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ExamplePole to pole orbiting satelliteLandsat-7

• 705-km altitude
• 16-day repeat cycle
• 185 km swath width
• Whisk-broom scanner
• Pixel resolution 30m
• 8 bands

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Spectral curves of Earth materials
Soil
Vegetation
Water
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Landsat bands 1-4 and spectral curves
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Soil
Vegetation
Water
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• Healthy
• Some air cavities in the mesophyll begin to
  collapse, results in a drop in IR, no change yet
  in visible
• Chloroplast deterioration increases red
  reflectance. Green reflectance decreases by a
  small amount. The overall effect is the
  yellowing of the leaf. Reflectance also
  decreases in the IR.
• Leafs cell structure collapses, red reflectance
  increases, the green peak disappears. Leaves
  appear brown

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http//science.nasa.gov/Realtime/jtrack/3d/JTrack3
d.html
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Some satellite applications

• Global
• Environmental monitoring
• Climate monitoring
• Regional
• Climate and weather
• Vegetation studies
• Urban growth
• Deforestation
• Geology

• Local
• Urban heat islands
• Precision farming
• Land use
• Infrastructure mapping

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Ocean temperature derived from NOAA-14 AVHRR -
Thermal infrared data
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Satellite ApplicationsWeather
Cloud temperature
coldest
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Weather Visible satellite image of Hurricane
Charley, Aug. 13, 2004
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Doppler radar image of Charley after landfall,
Aug 13th 2004
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Satellite ApplicationsGeology
Wind River, Wyoming
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Satellite ApplicationsEnvironmente.g. water
quality
Lake Erie
The Ohio River
Little Blue Run
Downtown Cleveland
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SeaWifs true color image of Great Lakes
Superior
Huron
Toronto
Michigan
Ontario
Detroit
Erie
Cleveland
Toledo
Pittsburgh
Chicago
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Chlorophyll A concentration from SeaWifs
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Satellite ApplicationsPrecision Farming
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Some websites

• Low resolution
• http//www.goes.noaa.gov/
• Moderate resolution
• http//landsat.gsfc.nasa.gov/
• http//landsat.gsfc.nasa.gov/earthasart/
• http//asterweb.jpl.nasa.gov/gallery/
• High resolution
• http//www.spaceimaging.com
• http//www.digitalglobe.com/