JpGU-AGU Joint Meeting 2017

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[EE] Oral

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

[P-EM14] [EE] Dynamics in magnetosphere and ionosphere

Sat. May 20, 2017 1:45 PM - 3:15 PM 105 (International Conference Hall 1F)

convener:Tomoaki Hori(Graduate school of Science, University of Tokyo), Yoshimasa Tanaka(National Institute of Polar Research), Aoi Nakamizo(Applied Electromagnetic Research Institute, National Institute of Information and Communications Technology), Mitsunori Ozaki(Faculty of Electrical and Computer Engineering, Institute of Science and Engineering, Kanazawa University), Chairperson:Motoharu Nowada(Shandong University), Chairperson:shun Imajo(Kyushu Univ.)

2:35 PM - 2:50 PM

[PEM14-04] Propagation and evolution of electric fields associated with solar wind pressure pulses based on spacecraft and ground-based observations

*Naoko Takahashi1, Yasumasa Kasaba1, Yukitoshi Nishimura2,3, Atsuki Shinbori4, Takashi Kikuchi4,5, Tomoaki Hori6, Yusuke Ebihara5, Nozomu Nishitani4 (1.Dep. Geophysics Graduate School of Science Tohoku University, 2.University of California, Los Angeles, 3.Boston University, 4.Institute for Space-Earth Environment Research, Nagoya University, 5.Research Institute for Sustainable Humanosphere, Kyoto University, 6.Department of Earth and Planetary Science, Graduate school of Science, The University of Tokyo)

We investigate spatial and temporal evolution of large-scale electric fields in the magnetosphere and ionosphere associated with sudden commencements (SCs) using multi-point equatorial magnetospheric (THEMIS, RBSP, GOES) and ionospheric (C/NOFS) satellites with radars (SuperDARN). A distinct SC event on March 17, 2013 and a statistical analysis of 130 SC events show that the magnetospheric electric field in the equatorial plane propagates from dayside toward nightside as a compressional wave. Estimated tailward propagation speed is about 1000–1100 km/s, which can be explained by a fast mode wave. The ionospheric electric field responds ~41 s after the onset of dayside magnetospheric electric field, which can be explained by the Alfvén wave speed. Tailward and downgoing field-aligned Poynting fluxes evaluated from THEMIS and RBSP data support these propagations. We also statistically derive a spatial distribution and time evolution of the magnetospheric electric field in the dawn-dusk direction (Ey). Our result shows that negative Ey (dawnward) propagates from noon toward the magnetotail, followed by positive Ey (duskward). At noon, negative Ey lasts for about 1 min, and positive Ey becomes dominant about 2 min after the SC onset. Negative Ey soon attenuates in the nightside region, while the positive Ey propagates fairly well to the pre-midnight or post-midnight regions while maintaining a certain amplitude. The enhancement of duskward electric field is affected by the evolution of the current system associated with the main impulse of SCs.