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Using Electromagnetic Waves

Remote sensors use electromagnetic energy to determine information about the region of earth being scanned. The sensors measure the radiance of electromagnetic waves emitted from either the Sun, the objects being scanned or the sensor itself. Different objects absorb and reflect specific parts of the spectrum, creating a "spectral signature". Scientists then use this signature to differentiate between particular objects on the Earth.

Data Interpretation

Specific algorithms have been developed to interpret the original data collected by the sensors into more appropriate information. For example, chlorophyll concentration in oceans and large lakes can be measured using the spectral range over which chlorophyll absorbs light: visible Blue (~400 nm) to visible Red (~700 nm). Lake or Sea Surface Temperatures can be estimated using the Thermal Infrared region of the electromagnetic spectrum (~10microns).  

Transmitting Data

Images are formed from a composite of rows scanned as the satellite orbits. Stored images are converted to radio waves and broadcasted to receiving stations using specific frequencies. (The main receiving site we use for images of the Great Lakes is maintained by a government installation in Wallops Island, VA.) Once the radio signal is received by the station, it can be translated back into a digital file. Satellite data is then validated through ship-based water samples, optical and temperature data.  


Remote Sensing Analysis, http://www.csc.noaa.gov/products/nchaz/htm/ccap5.htm.

Great Lakes Web Site, http://www.geo.mtu.edu/great_lakes/lakersi/cgi-bin/rsi_kitie/home.html. Michigan Technological University

What is Remote Sensing, http://www.ccrs.nrcan.gc.ca/ccrs/learn/tutorials/fundam/chapter1/chapter1_1_e.html. Canada Centre for Remote Sensing.

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This site was created by Katie Kerfoot  
Email questions about the content of this web page to : Judy Budd