Japan Geoscience Union Meeting 2015

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International Session (Oral)

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

[P-EM07] Space Weather, Space Climate, and VarSITI

Mon. May 25, 2015 9:00 AM - 10:45 AM 302 (3F)

Convener:*Ryuho Kataoka(National Institute of Polar Research), Yusuke Ebihara(Research Institute for Sustainable Humanosphere, Kyoto University), Yoshizumi Miyoshi(Solar-Terrestrial Environement Laboratory, Nagoya University), Toshifumi Shimizu(Institute of Space and Astronautical Science, JAXA), Ayumi Asai(Unit for Synergetic Studies of Space, Kyoto University), Hidekatsu Jin(National Institude of Information and Communications Technology), Tatsuhiko Sato(Japan Atomic Energy Agency), Kanya Kusano(Solar-Terrestrial Environment Laboratory, Nagoya University), Hiroko Miyahara(College of Art and Design, Musashino Art University), Takuji Nakamura(National Institute of Polar Research), Kazuo Shiokawa(Solar-Terrestrial Environment Laboratory, Nagoya University), Kiminori Itoh(Graduate School of Engineering, Yokohama National University), Chair:Kazuo Shiokawa(Solar-Terrestrial Environment Laboratory, Nagoya University)

10:30 AM - 10:45 AM

[PEM07-12] Properties of large amplitude geomagnetic sudden commencement (SC)

*Tohru ARAKI1, Atsuki SHINBORI2 (1.Polar Research Institute of China, 2.Research Institute for Sustainable Humanosphere, Kyoto University)

Keywords:geomagnetic sudden commencement(SC), interplanetary shock, LT variation, large amplitude

Araki [2014; EPS] confirmed that SC occurred on March 24, 1940 was largest since 1868. The amplitude is 310nT at Alibag and more than 273nT at Kakioka. Using the experimental relationship between SC amplitude dH and dynamic pressure Pd associated with interplanetary shock (IPS) [Siscoe et al. ; 1968], dH = A*d(Pd^0.5), the corresponding Pd increase was estimated as 400-500nPa.
When the magnetosphere is compressed by IPS, field aligned currents (FACs) and ionospheric currents (ICs) are induced in addition to the primary magnetopause current (MPC). The LT variations of SC amplitude is produced by them which should be taken into account in estimation of Pd using Siscoes relationship.
When Pd is larger than about 30nPa, the magnetopause enters into the inside of the geosynchronous orbit. At that time the configuration of the MPC, FAC and IC might be different and contribute differently to the LT variation of SC amplitude. Thus it is important to examine the LT variation of large SCs and reflect the result in estimation of Pd associated with IPS.
Here we study properties of large amplitude SC including its LT variation. .