The Advanced Very High Resolution Radiometer (AVHRR) instrument was flown on the first and subsequent TIROS-N series of polar orbiting spacecraft beginning in October of 1978. The satellite orbits the earth about 14 times each day and consecutive equatorial crossings are separated by about 25 degrees of longitude. The AVHRR generates data in three different modes, and data from each mode is ... available in a variety of formats. GAC (Global Area Coverage) data has a resolution of 4km that is derived from 1km resolution data. A non-board processor averages four out of every five pixels along every third scan line, and stores the data for subsequent transmission. GAC digital image data is available in mapped mosaics, orbital swaths and brightness composties. Some GAC derived products are Sea Surface Temperatures, Vegetation Indices and Heat Budget data. The AVHRR is a 4/5 channel radiometer with spectral bands in the visible, near infrared, and thermal infrared.