ERWIM - AN E-REGION WIND INTERFEROMETER

A field-widened Michelson interferometer designed to measure upper atm ospheric winds at three altitudes near the mesopause by using airglow emissions from (OS)-S-1, OH, and O-2 is described. Avery large path di fference (11 cm) is used to suppress the fringes from the hot F-region emission of (OS)-S-1 and to facilitate accurate measurements. Field w idening and thermal compensation are achieved over the large spectral range (557.7-866.0 nm) by the use of three types of glass in the inter ferometer's arms. The instrument was installed at Resolute Bay, Canada (74.3 N, 94.5 W), in November 1992 and has been operated remotely fro m Toronto for four winter seasons. Some examples of data are shown to illustrate ERWIN's performance. (C) 1996 Optical Society of America