HR: 1340h
AN: SM13A-1198    [Abstracts]
TI: Modeling of Radiation Belts Dynamics - Development of time dependent model and comparison with satellite data -
AU: * Miyoshi, Y S
EM: miyoshi@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Laboratory, Nagoya University, 3-13 Honohara, Toyokawa, 442-8507 Japan
AU: Jordanova, V K
EM: vania.jordanova@unh.edu
AF: University of New Hampshire, 39 College Road, Durham, NH 03824 United States
AU: Morioka, A
EM: morioka@pparc.geophys.tohoku.ac.jp
AF: Planetary Plasma and Atmospheric Research Center, Tohoku University, Aramaki Aoba, Sendai, 980-8578 Japan
AU: Obara, T
EM: T.Obara@nict.go.jp
AF: National Institute of Information and Communications Technology, 4-2-1 Nukui-Kitamachi, Koganei, 184-8795 Japan
AU: Reeves, G D
EM: reeves@lanl.gov
AF: Los Alamos National Laboratory, MS D-466, Los Alamos, NM 87544 United States
AU: Matsumoto, H
EM: matsumoto.haruhisa@jaxa.jp
AF: Japan Aerospace Exploration Agency, 1-1, Sengen 2chome, Tsukuba, 305-8505 Japan
AU: Goka, T
EM: goka.tateo@jaxa.jp
AF: Japan Aerospace Exploration Agency, 1-1, Sengen 2chome, Tsukuba, 305-8505 Japan
AB: Drastic changes of the relativistic electron population in the radiation belt during magnetic storms have been observed for many years. Typically, the relativistic electron flux decreases during the main phase of the storm, and then recovers and increases from late main phase to the recovery phase. Although many mechanisms for flux variation including both adiabatic and non-adiabatic process have been proposed, identification of the dominant process is difficult because many physical processes occur simultaneously. Thus, the development of the dynamical model based on physical processes is necessary for quantitative understanding of the radiation belts. In order to investigate physical processes in the radiation belts, we develop 1D, time-dependent, physical model for the radiation belts. In the model, we solve the Fokker-Planck equation for radial diffusion. Several loss processes such as wave-particle interactions and Coulomb collisions inside plasmasphere and strong diffusion and EMIC/chorus loss outside plasmasphere are included as life times. The model can calculate time variation of the radiation belts using time-dependent radial diffusion coefficient and the data from SOPA instrument on the geosynchronous LANL satellites as the outer boundary conditions. The energy spectrum data derived from SOPA instrument are parameterized by relativistic double Maxwellian. Firstly, we reproduced the equilibrium structure of the radiation belts; inner belt, slot region, and outer belt. Next, we calculate time variation of the radiation belts and compare with data of JAXA/MDS-1 (Tsubasa) satellite. From 2002 to 2003, the MDS-1 satellite measured the energetic electron distribution with geosynchronous transfer orbit, and we can discuss temporal and spatial variation together with spectrum hardness of relativistic electrons for all regions of the radiation belts. In order to evaluate the variation of the outer boundary condition and time dependent radial diffusion coefficient, we perform numerical experiment with varying parameters in the model. As an initial result, the time dependent boundary condition is important for the flux decrease during the main phase and increase in the outer portion. However, the time dependent boundary condition does not affect the variation of the inner portion. On the other hand, the time dependent radial diffusion coefficient is effective for flux variation of slot region and inner portion of the outer belt. Furthermore, it is reveled that the simulated flux is smaller than the observed. It is expected that further processes such as internal process is necessary in the outer radiation belt.
DE: 2700 MAGNETOSPHERIC PHYSICS
DE: 2720 Energetic particles, trapped
DE: 2730 Magnetosphere--inner
DE: 2753 Numerical modeling
DE: 2788 Storms and substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting