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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Discussion papers | Copyright
https://doi.org/10.5194/angeo-2018-107
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Regular paper 20 Sep 2018

Regular paper | 20 Sep 2018

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This discussion paper is a preprint. It is a manuscript under review for the journal Annales Geophysicae (ANGEO).

Comparison of gravity wave propagation direction observed by mesospheric airglow imaging at three different latitudes by using M-transform

Septi Perwitasari1,3, Takuji Nakamura1,2, Masaru Kogure2,1, Yoshihiro Tomikawa1,2, Mitsumu K. Ejiri1,2, and Kazuo Shiokawa4 Septi Perwitasari et al.
  • 1National Institute of Polar Research, Tokyo, 190-8518, Japan
  • 2Department of Polar Science, SOKENDAI (The Graduate University for Advanced Studies), Tokyo, 190-8518, Japan
  • 3National Institute of Aeronautics and Space (LAPAN) of Indonesia, Bandung, 40173, Indonesia
  • 4Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, 464-8601, Japan

Abstract. We have developed a user-friendly software based on Matsuda et al. (2014) 3D-FFT method (M-Transform) for airglow imaging data analysis, as a function on Interactive Data Language (IDL), in which users can customize the range of wave parameters to process when executing the program. Input of this function is 3D array of a time series of 2D airglow image in geographical coordinate. We have applied this new function to mesospheric airglow imaging data with slightly different observation parameters obtained for the period of April-May at three different latitudes; Syowa Station, the Antarctic (69°S, 40°E), Shigaraki, Japan (35°N, 136°E), and Tomohon, Indonesia (1°N, 122°E). Day-to-day variation of phase velocity spectrum at Syowa Station was smaller and propagation direction was mainly westward. At Shigaraki, the day-to-day variation of horizontal propagation direction was larger than at Syowa Station, and the variation at Tomohon was even larger. At Tomohon variation of nightly power spectrum magnitude was remarkable, which suggests intermittency of atmospheric gravity waves (AGWs). The average of nightly spectrum in April–May showed that at Syowa Station dominant propagation was westward with phase speed <50m/s, and at Shigaraki east/south-eastward propagation with phase speed up to ~80m/s was prevailing. A Tomohon, day-to-day variation was too strong to discuss about average characteristics, however it showed a phase speed up to ~100m/s and faster. The corresponding background wind profiles derived from MERRA-2 indicated that at Syowa Station, wind filtering played significant role in filtering out waves propagated eastward. On the other hand, at Shigaraki and Tomohon, the background winds were not strong enough to filter out the relatively high speed AGWs and that the dominant propagation direction was likely more related to the distribution/characteristic of the source region, at least in April and May.

Septi Perwitasari et al.
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Short summary
We have developed user-friendly program that can efficiently deal with extensive amounts of airglow data. We have applied this new program to airglow data obtained at different latitudes in polar, mid-latitude and equatorial region and demonstrated distinct difference of atmospheric gravity waves (AGWs) propagation characteristics and energy distribution. We aim to encourage other AGWs research groups to use the program and do comparison to reveal AGWs characteristics on more global scale.
We have developed user-friendly program that can efficiently deal with extensive amounts of...
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