posted on Feb, 12 2011 @ 05:21 PM
Okay folks, I'm doing my homework:
The Advanced Very High Resolution Radiometer (AVHRR) is a space-borne sensor embarked on the National Oceanic and Atmospheric Administration (NOAA)
family of polar orbiting platforms (POES). AVHRR instruments measure the reflectance of the Earth in 5 relatively wide (by today's standards)
spectral bands. The first two are centered around the red (0.6 micrometer, 0.5 THz) and near-infrared (0.9 micrometer, 0.3 THz) regions, the third one
is located around 3.5 micrometer, and the last two sample the thermal radiation emitted by the planet, around 11 and 12 micrometers, respectively.
The primary purpose of these instruments is to monitor clouds and to measure the thermal emission (cooling) of the Earth. These sensors have proven
useful for a number of other applications, however, including the surveillance of land surfaces, ocean state, aerosols, etc. AVHRR data are
particularly relevant to study climate change and environmental degradation because of the comparatively long records of data already accumulated
(over 20 years). The main difficulty associated with these investigations is to properly deal with the many limitations of these instruments,
especially in the early period (sensor calibration, orbital drift, limited spectral and directional sampling, etc).