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 °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 upperatmosphere neutral wind and temperature fields over a large region (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.