TY - JOUR
T1 - Comparison of gravity wave propagation directions observed by mesospheric airglow imaging at three different latitudes using the M-transform
AU - Perwitasari, Septi
AU - Nakamura, Takuji
AU - Kogure, Masaru
AU - Tomikawa, Yoshihiro
AU - Ejiri, Mitsumu K.
AU - Shiokawa, Kazuo
N1 - Funding Information:
Acknowledgements. The airglow imaging at Syowa was carried out by the Japanese Antarctic Research Expedition (JARE) of the Ministry of Education, Culture, Sports, Science and Technology (MEXT). The airglow imager in Tomohon is operated by the National Institute of Aeronautics and Space (LAPAN), Indonesia. The airglow imager in Shigaraki is operated by Institute for Space-Earth Environmental Research (ISEE), Nagoya University, in collaboration with the Research Institute for Sustainable Humanosphere, Kyoto University. This research was supported by JSPS KAKENHI grants (JP 15H02137, JP 15H05815, and JP 16H06286), projects KP-1 and KP-301 of the National Institute of Polar Research (NIPR), and by the JSPS Core-to-Core Program, B. Asia-Africa Science Platforms. This research was supported by the National Institute of Information and Communications Technology (NICT) Foreign Researcher Invitation Program. The MERRA-2 data used in this study have been provided by the Global Modeling and Assimilation Office (GMAO) at NASA Goddard Space Flight Center. This publication was supported by an NIPR publication subsidy.
Publisher Copyright:
© Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License.
PY - 2018/11/30
Y1 - 2018/11/30
N2 - We developed user-friendly software based on Matsuda et al.'s (2014) 3D-FFT method (Matsuda-transform, M-transform) for airglow imaging data analysis as a function of Interactive Data Language (IDL). Users can customize the range of wave parameters to process when executing the program. The input for this function is a 3-D array of a time series of a 2-D airglow image in geographical coordinates. We 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). The day-to-day variation of the phase velocity spectrum at the Syowa Station is smaller and the propagation direction is mainly westward. In Shigaraki, the day-to-day variation of the horizontal propagation direction is larger than that at the Syowa Station; the variation in Tomohon is even larger. In Tomohon, the variation of the nightly power spectrum magnitude is remarkable, which indicates the intermittency of atmospheric gravity waves (AGWs). The average nightly spectrum obtained from April-May shows that the dominant propagation is westward with a phase speed < 50ms-1 at the Syowa Station and east-southeastward with a phase speed of up to - 80ms-1 in Shigaraki. The day-to-day variation in Tomohon is too strong to discuss average characteristics; however, a phase speed of up to - 100ms-1 and faster is observed. The corresponding background wind profiles derived from MERRA-2 indicate that wind filtering plays a significant role in filtering out waves that propagate eastward at the Syowa Station. On the other hand, the background wind is not strong enough to filter out relatively high-speed AGWs in Shigaraki and Tomohon and the dominant propagation direction is likely related to the distribution and characteristics of the source region, at least in April and May.
AB - We developed user-friendly software based on Matsuda et al.'s (2014) 3D-FFT method (Matsuda-transform, M-transform) for airglow imaging data analysis as a function of Interactive Data Language (IDL). Users can customize the range of wave parameters to process when executing the program. The input for this function is a 3-D array of a time series of a 2-D airglow image in geographical coordinates. We 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). The day-to-day variation of the phase velocity spectrum at the Syowa Station is smaller and the propagation direction is mainly westward. In Shigaraki, the day-to-day variation of the horizontal propagation direction is larger than that at the Syowa Station; the variation in Tomohon is even larger. In Tomohon, the variation of the nightly power spectrum magnitude is remarkable, which indicates the intermittency of atmospheric gravity waves (AGWs). The average nightly spectrum obtained from April-May shows that the dominant propagation is westward with a phase speed < 50ms-1 at the Syowa Station and east-southeastward with a phase speed of up to - 80ms-1 in Shigaraki. The day-to-day variation in Tomohon is too strong to discuss average characteristics; however, a phase speed of up to - 100ms-1 and faster is observed. The corresponding background wind profiles derived from MERRA-2 indicate that wind filtering plays a significant role in filtering out waves that propagate eastward at the Syowa Station. On the other hand, the background wind is not strong enough to filter out relatively high-speed AGWs in Shigaraki and Tomohon and the dominant propagation direction is likely related to the distribution and characteristics of the source region, at least in April and May.
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U2 - 10.5194/angeo-36-1597-2018
DO - 10.5194/angeo-36-1597-2018
M3 - Article
AN - SCOPUS:85057615080
SN - 0992-7689
VL - 36
SP - 1597
EP - 1605
JO - Annales Geophysicae
JF - Annales Geophysicae
IS - 6
ER -