Tidal variability of the geomagnetic polar cap mesopause above Resolute Bay

Variability in the geomagnetic polar cap neutral wind near the mesopause ab ove Resolute Bay, Canada (74.9 degrees N, 93.9 degrees W) has been observed by a Fabry-Perot Interferometer, using a circle-to-line detection techniqu e (FPI/CLIO) to observe the OH Meinel emission. We present an analysis of t he first wind measurements obtained with the FPI/CLIO from December 1995 to March 1996. The OH(7,3) (892.0 nm) Doppler winds were analyzed for tidal o scillations (defined herein as oscillations with periods which are sub-harm onics of a solar day). Daily spectral analysis, using 50 relatively clear d ays showed that oscillations between, and including, 12 h and 8 h were freq uent throughout the winter season in both the meridional and the zonal wind s. A non-linear least squares fit, performed on the data from the Jan 22-30 interval, revealed that a 12 h tidal feature was dominant. Observations of the OH neutral winds show variations indicating strong tidal wave activity at the mesopause.