NOAA, The National Oceanic and Atmospheric Administration, has helped pioneer environmental uses for satellite technology. You see their work on the nightly TV News with up to the minute displays of weather patterns. They have developed and maintained a series of Earth-watching spacecraft since 1960 and maintain a database of millions of images and data sets. AVHRR and its derivative products, the vegetative indices (NVI or NDVI, etc.), are useful in Earth monitoring. The agency has been particularly useful in snow monitoring since it has frequent and large scale coverage. Image analysis can discern if the snow fields are melting and how thick they are by differing tones in the AVHRR image. It is also used for flood monitoring, regional drainage analysis, vegetation mapping, regional soil moisture content analysis, wildfire fuel mapping, fire detection, dust and sandstorm monitoring and some geologic and physiographic mapping projects.
There are several channels in the AVHRR image. The most commonly used are the first and second channels. The images you see on this CD-ROM have a 2-1-1 arrangement for the RGB (Red, Green and Blue) components. The first channel is from .58 to .68 micrometers (10-6m or ┬╡m) which corresponds roughly to the red visible spectrum of our vision. The second channel spans a portion of the near infrared wavelength (.72-1.10 micrometers) and indicates vegetation types and vigor, biomass, bodies of water, and soil moisture.
Image databases are available to the general public. Images may be ordered from NOAA/NEDIS/NCDC; Satellite Data Services Division; Room 100 Princeton Executive Center; Washington, D.C. 20233
