Tidal variability of the geomagnetic polar cap mesopause above Resolute Bay



Variability in the geomagnetic polar cap neutral wind near the mesopause above Resolute Bay, Canada (74.9°N, 94.9°W) has been observed by a Fabry-Perot Interferometer, using a circle-to-line detection technique (FPI/CLIO) to observe the OH Meinel emission. We present an analysis of the 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 oscillations (defined herein as oscillations with periods which are sub-harmonics of a solar day). Daily spectral analysis, using 50 relatively clear days showed that oscillations between, and including, 12 h and 8 h were frequent throughout the winter season in both the meridional and the zonal winds. 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.