[P-EM12] Coupling Processes in the Atmosphere-Ionosphere System

[PEM12-P14] First simultaneous observation of nighttime medium-scale traveling ionospheric disturbance (MSTID) by a ground airglow imager and the Arase satellite in the inner magnetosphere

*Kouki Kawai¹, Kazuo Shiokawa¹, Yuichi Otsuka¹, Yoshiya Kasahara², Fuminori Tsuchiya³, Ayako Matsuoka⁴, Yasumasa Kasaba³, Kazushi Asamura⁴, Satoshi Kasahara⁶, Yoshizumi Miyoshi¹, Shin-ichiro Oyama^1,7,8, Yoichi Kazama⁵ (1.Institute for Space-Earth Environmental Research, Nagoya Univ, Japan, 2.Kanazawa Univ, Japan, 3.Tohoku Univ, Japan, 4.Japan Aerospace Exploration Agency, 5.Academia Sinica, 6.Tokyo Univ, Japan, 7.Oulu Univ, Finland, 8.National Institute od polar Research)

Keywords:Medium-Scale Traveling Ionospheric disturbance (MSTID), Arase satellite, Optical Mesosphere thermosphere Imagers (OMTIs), Plasma Wave Experiment (PWE), Electric Field Detector (EFD), high Frequency Analyzer

Medium Scale Traveling Ionospheric Disturbance (MSTID) is the propagation of the electron density fluctuation in the ionospheric F-layer. The mechanism of MSTID generation is based on the theories of atmospheric gravity waves from the ground and ionospheric E-F coupling and Perkins instability. It is known by simultaneous observation of airglow imagers in both hemispheres that the MSTID has a mirror image structure at the magnetic conjugate hemisphere. If the MSTID is generated by the E-F coupling and Perkins instabilities and grow up with E×B drift, the polarization electric field associated with the growth of the MSTID should propagate along the magnetic field lines. So, we are expected to observe the electric field variations by the Arase satellite flying in the inner magnetosphere. This observation has never been reported. Therefore, in this study, we have analyzed the MSTID observed at 06:00:00-06:30:00 UT on November 3, 2018, in detail by the airglow camera at Gakona (62.39 N, 214.78 E), Alaska, and the Arase satellite in the inner magnetosphere. The purpose of this study is to understand the correspondence between the MSTID structure in the ionosphere and the electromagnetic field and plasma in the conjugate inner magnetosphere. The electric field observed by the electric field detector (EFD) and the electron density observed by the high frequency analyzer (HFA) of plasma wave experiment (PWE) on board the Arase satellite fluctuated associated with the structure of the MSTID, when the satellite footprint in the ionosphere crossed almost perpendicularly to the phase surface of the MSTID. We projected the electric field variations observed by the satellite onto the ionosphere. We found that the electric field variations were nearly perpendicular to the phase surface of the MSTID. This variation indicates the polarization field that causes the MSTID through E×B drift. We also inferred the direction of the possible Pedersen current and the background electric field from the observed direction of the propagation and the electric field variations in the ionosphere, though we could not obtain direct evidences of these current and electric field from the current observation. We discuss these observation results in relation to the generation and growth mechanisms of MSTIDs.