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trends of the 20th century:

• globalization (interregionalization)
• interdisciplinarization
• speeding up access to information

The Challenge:

To develop the capability to predict those changes that will occur in the next decade to centruy, both naturally and in response to human activity.
• global observations
• information systems and models
• worldwide political awareness

"To advance our understanding of the causes and effects of global change, we need new observations of the Earth. These measurements must be global and synoptic, tey must be long-term, and different processes such as atmospheric winds, ocean currents and b iological productivity e measured simultaneously. We have learned that major advances in h sciences have come from synthesis of new ideas dwn from such global synoptic observations. The synthesis of plate tectonics from large-scale data is a major step in understanding how the solid Earth works; the undof the dynamics of large-scale circulation of the atmosphereat comes from global observations has permitted a significant increasein the accuracy of weather predictions. ... Until the advent of satellites, we had no techniques that could satisfy the needs for long-term, global, synoptic measurement of different proceses on the Earth. Now we areon the verge of ... achieving signit advances in understanding the state of the Ear th, its changes, feedbacks, interactionsnd global trends on timescales of years to centuries." ResearcBriefings, 1985. Committee on Sciee, Engineering and Public Policy, National Academy of Sciences, Washington, DC.

EARTH SYSTEM SCIENCE MEASUREMENT PROGRAMS

• soild Earth:
  • plate motion and mantle operties
  • magnetic field
  • geological records
• fluid and biological Earth:
  • physical climate system
  • biogeochemical cycles
  • global moistur

EXAMPLES of proposed measurements:

• - wind stress
• - sea surface topography
• - ocean clorophyll concentration
• - global moise content
• - biome extent and productivity
  

• describing change: global observations
• understanding change: pattern to process
• simulating change: system models
• predicting change: decades to centuries

GLOBAL POSITIONING SYSTEM (GPS)

• latitude, longitude in real-time
• navigation on air, sea, land
• approximate costs:

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  ACCURACY (m)              RECEIVER COST ($)
  100                          1,000
   10                          5,000
    1                          5,000
    0.1                       10,000
    0.01                      20,000
  

CONSTELLATION

21 satellites with 3 operational sparesm 6 orbital planes, 55 degree inclination, 20,200 km, 12 hour orbit

MEASUREMENT SCHEME

GPS naviagtion is based on accurate measurement of time. Accuracy depends on the number of satellites seen (duration) and additional information on control points

GPS GROUND CONTROL

REMOTE SENSING of the ENVIRONMENT

Earth resources satellites
• - LANDSAT-1 (1972)
• - LANDSAT-5
  • sensors: MSS and TM
• - SPOT
  • sensors:HRV-P and HRV-MS
• - SEASAT (100 days)
• - RADARSAT (to be launched NOW!)

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WHAT IS REMOTE SENSING ABOUT?

working definition: "inference on physical, biological, chemical and/or geographical characteristics of planetary features based on interactions with electromagnetic radiation, and their measurement"

ELECTROMAGNETIC RADIATION
• spectrum [wavelength/frequency]
  • optical: visible + NIR
  • thermal IR
  • microwave
• reflect, transmit, absorb
• blackbody/greybody [Lambert]
• solar radiation characteristics
  • spectral density
  • atmospheric windows
  • scattering

MEASUREMENT OF EM-RADIATION
• spatial resolution: 10-1000 m
• temporal resolution: 1-18 days
• spectral resolution: 1-200 channels

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SPECTRAL CHARACTERISTICS
• matter-energy interaction

  REFLECTANCE

• finding (a limited number of) spectral intervals (bands) to discriminate/identify/recognize Earth surface features
• the quantitative approach

  CLASSIFICATION

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IMAGING
• pixels

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GEOGRAPHICAL INFORMATION SYSTEMS

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