Characteristics of mesospheric gravity waves over Antarctica observed by Antarctic Gravity Wave Instrument Network imagers using 3‐D spectral analyses

• Published in: Journal of geophysical research. Atmospheres 2017-09, Vol.122 (17), p.8969-8981
• Main Authors: Matsuda, Takashi S., Nakamura, Takuji, Ejiri, Mitsumu K., Tsutsumi, Masaki, Tomikawa, Yoshihiro, Taylor, Michael J., Zhao, Yucheng, Pautet, P.‐Dominique, Murphy, Damian J., Moffat‐Griffin, Tracy
• Format: Article
• Language: English
• Subjects: Airglow; airglow imaging; ANGWIN; Antarctica; Atmospheric pressure; critical level filtering; Direction; Filtration; Fourier transforms; Geophysics; Gravitational waves; Gravity; Gravity waves; Inertia; mesospheric gravity wave; Mesospheric gravity waves; Phase velocity; Spectra; spectral analysis; Statistical analysis; Statistical methods; Temporal variations; Velocity; Wave energy; Wave generation; Wave period; Wave power; Wave propagation; Wind effects; Wind measurement
• ISSN: 2169-897X; 2169-8996
• DOI: 10.1002/2016JD026217

We have obtained horizontal phase velocity distributions of the gravity waves around 90 km from four Antarctic airglow imagers, which belong to an international airglow imager/instrument network known as ANGWIN (Antarctic Gravity Wave Instrument Network). Results from the airglow imagers at Syowa (69°S, 40°E), Halley (76°S, 27°W), Davis (69°S, 78°E), and McMurdo (78°S, 167°E) were compared, using a new statistical analysis method based on 3‐D Fourier transform (Matsuda et al., 2014) for the observation period between 7 April and 21 May 2013. Significant day‐to‐day and site‐to‐site differences were found. The averaged phase velocity spectrum during the observation period showed preferential westward direction at Syowa, McMurdo, and Halley, but no preferential direction at Davis. Gravity wave energy estimated by I′/I was ~5 times larger at Davis and Syowa than at McMurdo and Halley. We also compared the phase velocity spectrum at Syowa and Davis with the background wind field and found that the directionality only over Syowa could be explained by critical level filtering of the waves. This suggests that the eastward propagating gravity waves over Davis could have been generated above the polar night jet. Comparison of nighttime variations of the phase velocity spectra with background wind measurements suggested that the effect of critical level filtering could not explain the temporal variation of gravity wave directionality well, and other reasons such as variation of wave sources should be taken into account. Directionality was determined to be dependent on the gravity wave periods. Key Points Various variabilities of the mesospheric gravity waves are found for the first time by an airglow network observation in the Antarctic The phase velocity spectrum that indicated wind filtering effect of gravity waves is significant over Syowa, Halley, and McMurdo Over Davis, however, no preferential propagation direction is found, which could be because of secondary wave generation