WINDII, THE WIND IMAGING INTERFEROMETER ON THE UPPER-ATMOSPHERE RESEARCH SATELLITE

The WIND imaging interferometer (WINDII) was launched on the Upper Atm osphere Research Satellite (UARS) on September 12, 1991. This joint pr oject, sponsored by the Canadian Space Agency and the French Centre Na tional d'Etudes Spatiales, in collaboration with NASA, has the respons ibility of measuring the global wind pattern at the top of the altitud e range covered by UARS. WINDII measures wind, temperature, and emissi on rate over the altitude range 80 to 300 km by using the visible regi on airglow emission from these altitudes as a target and employing opt ical Doppler interferometry to measure the small wavelength shifts of the narrow atomic and molecular airglow emission lines induced by the bulk velocity of the atmosphere carrying the emitting species. The ins trument used is an all-glass field-widened achromatically and thermall y compensated phase-stepping Michelson interferometer, along with a ba re CCD detector that images the airglow limb through the interferomete r. A sequence of phase-stepped images is processed to derive the wind velocity for two orthogonal view directions, yielding the vector horiz ontal wind. The process of data analysis, including the inversion of a pparent quantities to vertical profiles, is described.