VISSR Atmospheric Sounder (VAS)

P. J. Minnett, Brookhaven National Laboratory

The VISSR (Visible and Infrared Spin-Scan Radiometer) Atmospheric Sounder (VAS) is a combined imaging and sounding device on the GOES (Geostationary Operational Environmental Satellite) series of geosynchronous satellites operated by the U.S. National Oceanic and Atmospheric Administration (NOAA). VAS has one channel in the visible part of the spectrum (0.55 m - 0.75 m). This channel comprises signals from eight detectors and six infrared detectors, which, by using a filter-wheel, make up 12 channels. The spectral positions of the channels are designed to permit the measurement of atmospheric profiles of temperature and humidity, as well as surface temperature. In addition, the vertical flux divergence of infrared radiation, the cooling-rate profile, can be estimated (Smith and Woolf 1983). 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.