ALL-SKY DOPPLER INTERFEROMETER FOR THERMOSPHERIC DYNAMICS STUDIES

An efficient, all-sky input optical system has been mated to a 100-mm-aperture Fabry-Perot interferometer that employs a cooled (-150 degrees C) CCD as a photon detector to create an all-sky Doppler interferometer. The instrument is capable of simultaneously measuring Doppler shifts and widths of nightglow emission lines from many different points in the sky, thereby providing determinations of upper-atmosphere neutral wind and temperature fields over a large region (to approximate to 2000 km in extent). For OI 630-nm (thermosphere) and OH 799.6-nm (mesopause) nightglow emissions, exposure times of 5-15 min provide good-quality interferometric images. The capability of the all-sky Doppler interferometer is illustrated by examples of thermospheric wind and temperature fields measured over Millstone Hill, Massachusetts.