[P-EM12] Dynamics of the Inner Magnetospheric System

[PEM12-P32] Plasma waves causing 20 Hz intensity modulation of pulsating aurora: High-speed Tjörnes-Arase-Syowa conjugate observation

*Herbert Akihito Uchida¹, Ryuho Kataoka^2,1, Kiyoka Murase¹, Shoya Matsuda³, Yoshiya Kasahara⁴, Masafumi Shoji⁵, Yoshizumi Miyoshi⁵, Iku Shinohara³, Ayako Matsuoka⁶, Satoshi Kurita⁷, Keisuke Hosokawa⁸, Shun Imajo⁵ (1.The Graduate University for Advanced Studies, 2.National Institute of Polar Research, 3.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 4.Kanazawa University, 5.Institute for Space–Earth Environmental Research, Nagoya University, 6.Kyoto University, 7.Research Institute for Sustainable Humanosphere, Kyoto University, 8.University of Electro-Communications)

Keywords:Pulsating aurora, Chorus waves, High-speed observation

We show the evidence of the simultaneously observed ~20 Hz intensity modulation of the auroral luminosity and the chorus wave intensity, and the evolution of pulsating aurora in terms of the transition of on and off of the pulsating patch, patch size, and pulsating period in different timescales. Pulsating auroras were observed by ground-based high-speed imagers after an auroral breakup at Tjörnes in Iceland and at its magnetic conjugate station, Syowa Station in Antarctica simultaneously on 22 September 2018. Two identical all-sky imagers at both stations and a narrow field-of-view imager at Syowa station were used to elucidate the hierarchical structure of the modulation in the auroral luminosity and the evolution of pulsating patches at different time scales. A few minutes before the main pulsation start, a fast intensity modulation of ~20 Hz was identified by the narrow field-of-view imager with ~3 Hz modulation in a small aurora patch. The foot-print of the Arase satellite was located within the all-sky field of view at that time, and the Plasma Wave Experiment onboard the Arase satellite observed chorus emissions whose intensity was modulated at the same period of the auroral fast intensity modulation. The patch size and the pulsation period evolved in time at both hemispheres and the period settled in the period of main pulsation. The pulsating patches differ in its shape and period between both hemispheres although several synchronized patches were also observed when the pulsating aurora drifted away from the all-sky field-of-view.