Japan Geoscience Union Meeting 2018

Presentation information

[EE] Oral

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

[P-EM15] Dynamics in magnetosphere and ionosphere

Sun. May 20, 2018 10:45 AM - 12:15 PM 303 (3F International Conference Hall, Makuhari Messe)

convener:Yoshimasa Tanaka(National Institute of Polar Research), Tomoaki Hori(Institute for Space-Earth Environmental Research, Nagoya University), Aoi Nakamizo(情報通信研究機構 電磁波研究所, 共同), Mitsunori Ozaki(Faculty of Electrical and Computer Engineering, Institute of Science and Engineering, Kanazawa University), Chairperson:Shinbori Atsuki(ISEE, Nagoya Univ.), Sato Yuka(National Institute of Polar Research)

11:30 AM - 11:45 AM

[PEM15-10] Pathway and conversion of solar wind energy to ionosphere: Global MHD simulation result

*Yusuke Ebihara1, Naoki Kamiyoshikawa1, Takashi Tanaka2 (1.Research Institute for Sustainable Humanosphere, Kyoto University, 2.Kyushu University)

Keywords:Substorm, Energy conversion and pathway, MHD simulation

A large amount of energy is consumed in the auroral ionosphere during the substorms. An immediate question is where the energy comes from. We analyzed the results of the global magnetohydrodynamics (MHD) simulation that is capable of reproducing sudden intensification of the Region 1-sense field-aligned current and subsequent auroral electrojet. The solar wind energy is converted to the electromagnetic energy in the cusp/mantle region when the interplanetary magnetic field is southward. The electromagnetic energy is transported to the ionosphere. We introduced an integral curve of the Poynting flux (S-curve) to show a pathway of the electromagnetic energy. The S-curve shows a spiral moving toward the ionosphere. Just before the expansion onset, the near-Earth reconnection initiates 3-dimensional redistribution of the magnetosphere. Flow shear in the near-Earth region results in the generation of the near-Earth dynamo and the onset FACs as well. In the near-Earth dynamo, the electromagnetic energy is converted to the thermal energy and the kinetic energy (known as bursty bulk flow), followed by the electromagnetic energy. About 1% of solar wind energy is converted to the electromagnetic energy in the cusp/mantle dynamo. About 25-33% of the electromagnetic energy generated in the cups/mantle dynamo is consumed in the ionosphere.