AIRBORNE SCANNING SPECTROMETER FOR REMOTE-SENSING OF CLOUD, AEROSOL, WATER-VAPOR, AND SURFACE-PROPERTIES

An airborne scanning spectrometer was developed for measuring reflecte d solar and emitted thermal radiation in 50 narrowband channels betwee n 0.55 and 14.2 mu m. The instrument provides multispectral images of outgoing radiation for purposes of developing and validating algorithm s for the remote sensing of cloud, aerosol, water vapor, and surface p roperties from space. The spectrometer scans a swath width of 37 km, p erpendicular to the aircraft flight track, with a 2.5-mrad instantaneo us field of view. Images are thereby produced with a spatial resolutio n of 50 m at nadir from a nominal aircraft altitude of 20 km. Nineteen of the spectral bands correspond closely to comparable bands on the M oderate Resolution Imaging Spectroradiometer (MODIS), a facility instr ument being developed for the Earth Observing System to be launched in the late 1990s. This paper describes the optical, mechanical, electri cal, and data acquisition system design of the MODIS Airborne Simulato r and presents some early results obtained from measurements acquired aboard the National Aeronautics and Space Administration ER-2 aircraft that illustrate the performance and quality of the data produced by t his instrument.