P. J. Minnett, Brookhaven National Laboratory
The Advanced Very High Resolution Radiometer Mk. 2 (AVHRR/2) is a five-channel imaging device which forms part of the payload of the TIROS-N (Television Infrared Operational Satellite) series of polar-orbiting weather satellites operated by the U.S. National Oceanic and Atmospheric Administration (NOAA). The five channels comprise two in the visible-near infrared, one in the mid-infrared, and two in the thermal infrared. The channels (Table 1) are situated in regions of the spectrum where the atmosphere is relatively transparent and so most of the signal registered by the instrument originates from the ocean or land surface, or from the tops of clouds. The infrared channels of the radiometer are calibrated using an on-board blackbody calibration target, the radiometric measurements of which are used in conjunction with measurements of cold space in a linear calibration procedure.