<title>GOES Sounder overview</title>

Abstract

The GOES Sounder is similar in appearance, size, and design to the GOES Imager. It provides independent radiomen-ic sounding of the atmosphere from GOES-East and GOES-West (GOES 8 and 9), which was accomplished on previous GOES by a single instrument with responsibility split between the functions of imaging and sounding. With 19 channels ranging from 0.70 m to 14.71 m, the Sounder probes the atmosphere to measure radiance at different depths (altitudes) while also monitoring surface and atmospheric temperatures, ozone, water vapor content, and cloud cover by means of the calibration of radiance data at selected wavelengths.Like the Imager, the Sounder scans the full earth, and can be commanded to scan local regions of interest. The scan mirror steps across the disk of the earth in synchronization with a dead zone on a filter wheel. The filters defme 18 of the channels as they rotate on the wheel in the path of light split into three beams traveling to detectors divided into longwave, midwave, and shortwave arrays. For visible (0.70 m) sounding of cloud cover, energy is split off ahead of the filter wheel and passed to the 19th channel and also to star sensing detectors used for instrument navigation.

Thermal Analysis of Radiometer Onboard a Geostationary Satellite

“…The radiometer is required to operate 24 h a day in a very harsh thermal environment. During a single diurnal period, the optics are exposed to the direct view of the sun for approximately 4 h during the day and the deep space during the remaining periods [1][2][3][4]. Even with the highly reflective optical surfaces, the scan mirrors still experience large temperature excursions during the heating and cooling periods [5].…”