Japan Geoscience Union Meeting 2018

Presentation information

[EE] Oral

P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM16] Dynamics of Earth's Inner Magnetosphere and Initial Results from Arase

Tue. May 22, 2018 10:45 AM - 12:15 PM 303 (3F International Conference Hall, Makuhari Messe)

convener:Danny Summers(Memorial University of Newfoundland), Yoshizumi Miyoshi(Institute for Space-Earth Environmental Research, Nagoya University), Keisuke Hosokawa(電気通信大学大学院情報理工学研究科, 共同), Yusuke Ebihara(Research Institute for Sustainable Humanosphere, Kyoto University), Chairperson:Hosokawa Keisuke(The University of Electro-Communications)

11:15 AM - 11:30 AM

[PEM16-27] Azimuthally propagating ionospheric flow fluctuations during storm times as seen from satellite-radar conjunctions

★Invited Papers

*Tomoaki Hori1, Nozomu Nishitani1, Simon G. Shepherd2, J. M. Ruohoniemi3, Martin G Connors4, Mariko Teramoto1, Shin'ya Nakano5, Kunihiro Keika6, Kanako Seki6, Naoko Takahashi6, Satoshi Kasahara6, Shoichiro Yokota7, Takefumi Mitani8, Takeshi Takashima8, Nana Higashio9, Ayako Matsuoka8, Kazushi Asamura8, Yoichi Kazama10, Shiang-Yu Wang10, Sunny W. Y. Tam11, Yoshizumi Miyoshi1, Iku Shinohara8 (1.Institute for Space-Earth Environmental Research, Nagoya University, 2.Dartmouth College, 3.Virginia Tech, 4.Athabasca University, 5.Institute of Statistical Mathematics, 6.University of Tokyo, 7.Graduate school of Science, Osaka University, 8.ISAS, JAXA, 9.TKSC, JAXA, 10.Institute of Astronomy and Astrophysics, Academia Sinica, Taiwan, 11.Institute of Space and Plasma Sciences, National Cheng Kung University, Taiwan)

The recent Super Dual Auroral Radar Network (SuperDARN) observations show that ionospheric flow fluctuations of the mHz or lower frequency range appear even in the subauroral to mid-latitude region during magnetic storm times. An intriguing feature of the flow fluctuations is that they appear to propagate azimuthally either westward or eastward, and occasionally bifurcate toward the both directions. Taking a closer look with high spatial resolution measurements provided by the radars reveals that those flow fluctuations consist of meso-scale patchy structures of ionospheric convection with a significant latitudinal flow component and a longitudinal scale of ~1h MLT. The azimuthal propagation properties strongly suggest that westward-drifting ions and eastward-drifting electrons of tens of keV in the inner magnetosphere can be the moving sources responsible for excitation of the flow fluctuations seen at the ionospheric height. Recent observations in the inner magnetosphere by the Arase satellite and the Van Allen Probes have provided excellent evidence for it as well as a good opportunity to examine their magnetospheric counterpart in further detail. The close conjugate observations of the radars and the satellites reveal that multiple drifting clouds of ions and electrons can be mapped to the electric field fluctuations propagating westward and eastward, respectively, in the ionosphere. The most likely interpretation for it would be that meso-scale pressure gradients carried by drifting ring current ions and electrons distort field lines one after another as they drift through the inner magnetosphere.