AVHRR

AVHRR, short for Advanced Very High Resolution Radiometer, is a multi-spectral imaging radiometer carried on NOAA’s polar-orbiting satellites since the late 1970s. It is designed to provide near-global, daily coverage by scanning across the satellite’s track and collecting data in multiple spectral bands that span from visible to thermal infrared.

The instrument supports a range of meteorological and environmental applications. Reflectance data from visible and near-infrared bands are used for cloud detection, surface characterization, and vegetation monitoring (including indices such as NDVI). Thermal infrared channels enable estimates of land and sea surface temperatures, while additional bands support fire detection, aerosol studies, and other atmospheric observations.

AVHRR has undergone several generations, including AVHRR/1, AVHRR/2, and AVHRR/3, with improvements in radiometric calibration, noise reduction, and channel configurations. Common data products include reflectance in visible and near-infrared bands, vegetation and land surface monitoring metrics, and temperature-derived products from the thermal channels. Spatial resolution varies by band and sensor, typically on the order of 1 to 4 kilometers at nadir, with a wide scanning swath to achieve broad coverage.

Operational since 1978, AVHRR data have contributed to a long-running, near-real-time capability for weather forecasting, climate research, and environmental monitoring. Data are archived and distributed by NOAA, NASA, and partner agencies, and the instrument has influenced subsequent remote-sensing radiometers used in global Earth observation programs.