Observations of short-period waves with an all-sky camera in the infrared airglow above Yakutsk

Abstract

The parameters of internal gravity waves detected based on the variations in the hydroxyl molecule emission are statistically analyzed. The wave structures were registered with an all-sky infrared camera at Maimaga optical station (ϕ = 63° N, λ = 129.5° E). The data obtained in the winter period of 1998–2002 are analyzed. In total, 162 waves, the majority of which propagated westward, were recorded. The wavelengths vary from 15.4 to 100 km (the average value is ∼31 km); the observed horizontal phase velocities change from 19 to 166 m/s (the average value is ∼60 m/s), and the estimated periods are 9–90 min (the average value is ∼11 min). The statistical characteristics of the waves do not differ from those of similar waves at middle and low latitudes. The azimuthal dependence of the wave propagation direction is consistent with the theory of wave filtration by a background wind in the middle atmosphere. Probable sources of the waves are mountain ranges located at a distance of 200 km east of the observation site. Somewhat greater values of the mean wavelength and wave propagation velocities than those recorded at lower latitudes may be due to the lower loss of energy and velocity of the waves during their propagation from the source to the mesosphere, although other causes are not ruled out. Ripple-type waves have the same direction of propagation as band-type waves.