Gravity Wave Observations in the Polar Mesopause Region

The E-Region Wind Interferometer at the Polar Environment Atmospheric Research Laboratory (Eureka, Nu, 80 N) provides observations of airglow intensity and wind (using Doppler shifts in three airglow emissions (oxygen green line, hydroxyl and O₂)) in the Polar mesopause region. An all sky camera which images airglow intensity is co-located with the interferometer. Wind observations are taken in the vertical and four cardinal directions at three heights with a cadence of ~6 minutes and precisions of 1-2 m/s (oxygen green line and hydroxyl) and 4 m/s (O₂). These winds are volume emission rate weighted wind observations and hence waves with vertical wavelengths over ~6 km and periods greater than ~20 minutes can be resolved. Correlations between the wind signatures in opposite directions provide the means to diagnose the zonal and meridional wavelengths and horizontal phase velocity of waves. Vertical wavelengths are determined using correlations between winds from different heights (using different airglow emissions). The intensity signatures are analyzed for the same wave characteristics. In this paper, waves with periods in the range of an hour to 12 hours are described and interpreted in terms of linear gravity wave theory.