[P-EM12] 大気圏ー電離圏結合

[PEM12-20] 多地点・長期に得られた夜間大気光画像の3次元FFT解析に基づく中間圏・電離圏波動の緯度経度特性の研究

★招待講演

*塩川 和夫¹、大塚 雄一¹、中村 卓司² (1.名古屋大学宇宙地球環境研究所、2.国立極地研究所)

キーワード：大気光、大気重力波、伝搬性電離圏擾乱

In this presentation, we review recent results obtained by the 3-dimentional Fast Fourier Transform (FFT) analysis of multi-point airglow images reported by Takeo et al. (2017) and Tsuchiya et al. (2018; 2019; 2020). We used the airglow images taken by the Optical Mesosphere Thermosphere Imagers (OMTIs) at Shigaraki (SGK) (35^oN, 136^oE, 1999-2017) and Rikubetsu (RIK) (44^oN, 144^oE, 1999-2017), Japan, Athabasca (ATH), Canada, (55^oN, 247^oE, 2005-2017), and Magadan (MGD), Russia (60^oN, 151^oE, 2008-2017). First we estimated phase-velocity spectra of mesospheric gravity waves in 557.7-nm airglow images and medium-scale traveling ionospheric disturbances (MSTIDs) in 630.0-nm airglow images. For all the stations, mesospheric gravity waves in 557.7-nm airglow images tend to propagate poleward in summer and equatorward in winter (except for MGD). The summer-time poleward waves may be caused by duct propagation of gravity waves from tropospheric convection source. Wind filtering effect by mesospheric jet is clearly seen over Japan (SGK and RIK), while it becomes less evident at high latitudes in ATH and MGD. For MSTIDs in 630.0-nm airglow images, southwestward-propagating waves are dominant at SGK, RIK, and ATH (except for summer), while they are not evident at MGD. Clear anti-correlation of MSTID power (amplitudes) and 11-year solar activity can be found at SGK, RIK, and ATH. We also show wavenumber spectra of gravity waves and MSTIDs at these stations. Weak positive correlations were obtained between the daily wave power of gravity waves in 557.7-nm images and MSTIDs in 630.0-nm images, suggesting that the MSTIDs in the thermosphere may be partially generated by the gravity waves from the mesopause region.



References:

Takeo et al., JGR, 10.1002/2017JA023919, 2017.

Tsuchiya et al., JGR, 10.1029/2018GL080222, 2018.

Tsuchiya et al., JGR, 10.1029/2019JA026783, 2019.

Tsuchiya et al., JGR, 10.1029/2019JA026807, 2020.