Wilbert R. Skinner, Paul B. Hays, Heinz J. Grassl, David A. Gell, Mark D. Burrage, Alan R. Marshall and Julie Kafkalidis (1996) The High Resolution Doppler Imager: Instrument perfromance in orbit since late 1991 Proc. SPIE 2830, 202-214 (1996)

Abstract:

The High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Satellite has been providing measurements of the wind field in the stratosphere, mesosphere and lower thermosphere since November 1991. Mesospheric temperatures, ozone and 0(D), as well as stratospheric aerosol extinctions, are also recovered. The instrument characteristics have been carefully monitored during the nearly five years of operation. The instrument thermal and long-term drifts can be removed from the data and wind biases are less than about 2 m/s. The interferometer sensitivity has varied by about 3%, most likely due to changes in the parallelism of one of the etalons. There is no indication that either the radiator or thermal blankets have shown any significant degradation. Recently, the azimuth slew rate of the telescope has displayed some variation, which may indicate an increase of bearing friction.