| The National Oceanic and Atmospheric Administration (NOAA) operates the United States meteorological satellite programs. Improvements on the first U.S. polar orbiting satellite, known as TIROS (Television and Infrared Observational Satellite), eventually led to the launch of today's advanced weather satellites in this series, called NOAA satellites. |  |
Presently, there are four operational NOAA satellites in orbit: NOAA-10, NOAA-12, NOAA-14 and NOAA-15. These polar-orbiting spacecraft have orbital periods of approximately 102 minutes.
Each of these NOAA weather satellites carry an array of different sensors which can over the earth remotely with a resolution of approximately 1 km. The primary sensor on board is called the Advanced Very High-Resolution Radiometer—or AVHRR for short. (A radiometer is an instrument which measures the intensity of light.) The AVHRR can measure light reflected from the earth in 5 different wavelengths (or channels):
| Channel | Spectral Bandwidth | Types of Data Provided |
| Visible | 0.58 - 0.68 µm | daytime cloud cover, snow cover, ice |
| Near Infrared | 0.73 - 1.10 µm | daytime cloud cover, surface water, vegetation |
| Thermal Infrared | 3.55 - 3.93 µm | nighttime cloud cover, sea surface temperature, monitoring of volcanoes and forest fires |
| Thermal Infrared | 10.3 - 11.3 µm | daytime/nighttime cloud cover, land and sea temperatures |
| Thermal Infrared | 11.5 - 12.5 µm | daytime/nighttime cloud cover, land and sea temperatures, water vapor corrections when used with channel 4 |
The AVHRR data are transmitted down to an earth station capable of receiving High-Resolution Picture Transmission (or HPRT for short). The HPRT signal, which is broadcast at 1698.0 MHz, carries all 5 channels of data.
