Summary
Atmospheric gravity waves (AGWs), which are generated in the lower atmosphere, transport significant amount of energy andmomentum into the mesosphere and lower thermosphere and cause the mean wind accelerations in the mesosphere. This momentumdeposit drives the general circulation and affects the temperature structure. Among many parameters to characterize AGWs,horizontal phase velocity is very important to discuss their vertical propagation. Airglow imaging is a useful technique for investigatingthe horizontal structures of AGWs around mesopause. An international airglow imager (and other instruments) networkin the Antarctic, named ANGWIN (Antarctic Gravity Wave Imaging/Instrument Network) was started in 2011. Its purpose is tounderstand characteristics of mesospheric gravity waves and their impacts on the Mesosphere and Lower Thermosphere (MLT)environment over Antarctica.In this study, we compared distributions of horizontal phase velocities of gravity waves at around 90 km altitude over differentlocations using our new statistical analysis method based on 3-D Fourier transform, developed by Matsuda et al. (2014). Thecomparison has been carried out for airglow imagers at four stations, that are, Syowa (69S, 40E), Halley (76S, 27W), Davis (69S,78E) and McMurdo (78S, 156E), out of the ANGWIN imagers, for the observation period between April 6 and May 21 in 2013.Not only horizontal propagation characteristics, gravity wave energies can also be quantitatively compared, indicating a smallerGW activity in higher latitudes. The presentation will be focused on showing the performance of the new statistical techniquefor studying gravity waves.
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