HR: 15:25h
AN: SM43E-07    [Abstracts]
TI: Variations in the ring current and inner-magnetospheric electric field deduced from data assimilation of IMAGE/HENA data
AU: * Nakano, S
EM: shiny@ism.ac.jp
AF: The Institute of Statistical Mathematics, 4-6-7 Minami-Azabu, Minato, Tokyo, 106-8569, Japan
AU: * Nakano, S
EM: shiny@ism.ac.jp
AF: Japan Science and Technology Agency, Risona-Maruha Bldg. 18F, 1-1-2 Ote-machi, Chiyoda, Tokyo, 100-0004, Japan
AU: Ueno, G
EM: gen@ism.ac.jp
AF: The Institute of Statistical Mathematics, 4-6-7 Minami-Azabu, Minato, Tokyo, 106-8569, Japan
AU: Ueno, G
EM: gen@ism.ac.jp
AF: Japan Science and Technology Agency, Risona-Maruha Bldg. 18F, 1-1-2 Ote-machi, Chiyoda, Tokyo, 100-0004, Japan
AU: Ebihara, Y
EM: ebihara@stelab.nagoya-u.ac.jp
AF: Institute of Advanced Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464- 8601, Japan
AU: Fok, M
EM: mei-ching.h.fok@nasa.gov
AF: NASA Goddard Space Flight Center, NASA GSFC, Code 673, Greenbelt, MD 20771, United States
AU: Ohtani, S
EM: Shin.Ohtani@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MDq 20723-6099, United States
AU: Brandt, P C
EM: pontus.brandt@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MDq 20723-6099, United States
AU: Mitchell, D G
EM: don.mitchell@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MDq 20723-6099, United States
AU: Keika, K
EM: kunihiro.keika@oeaw.ac.at
AF: Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, Graz, A- 8042, Austria
AU: Higuchi, T
EM: higuchi@ism.ac.jp
AF: The Institute of Statistical Mathematics, 4-6-7 Minami-Azabu, Minato, Tokyo, 106-8569, Japan
AU: Higuchi, T
EM: higuchi@ism.ac.jp
AF: Japan Science and Technology Agency, Risona-Maruha Bldg. 18F, 1-1-2 Ote-machi, Chiyoda, Tokyo, 100-0004, Japan
AB: We examine the relationship between the temporal variation of the ring current and that of the inner- magnetospheric electric field during a magnetic storm by using data assimilation of ENA observations into a kinetic ring current simulation. Since the dynamics of ring current ions are strongly controlled by the electric field, it is important to know the electric field in the inner magnetosphere in order to discuss the ring current evolution. However, due to the lack of direct observations, it is basically difficult to know the global distribution of the electric field for each storm event. By applying a data assimilation technique to a kinetic ring current model, we can estimate not only the ring current distribution but also the electric potential distribution and some other parameters on the basis of both observations and physical laws described by the kinetic code. We assimilated ENA observations from the IMAGE satellite into a kinetic ring current model developed by Fok et al. (2001) using the merging particle filter algorithm, and the distributions of the ring current and electric potential provided by this ENA data assimilation was examined. It is indicated that a westward electric field appears around the post- midnight and that it feeds high energy ions into the ring current region. It is also suggested that the variation of this westward electric field substantially controls the high-energy part of the ring current. The possible implications of the results are also discussed.
DE: 2730 Magnetosphere: inner
DE: 2753 Numerical modeling
DE: 2778 Ring current
DE: 2788 Magnetic storms and substorms (7954)
DE: 7959 Models
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting