HR: 09:45h
AN: SM21B-08    [Abstracts]
TI: Statistical Relationship between Large-scale Field-aligned Currents and Particle Precipitation
AU: * Ohtani, S
EM: Shin.Ohtani@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, United States
AU: Wing, S
EM: Simon.Wing@jhuapl.edu
AF: The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, United States
AU: Ueno, G
EM: gen@ism.ac.jp
AF: Institute of Statistical Mathematics, 4-6-7 Minami-Azabu, Tokyo, 106-8569, Japan
AU: Higuchi, T
EM: higuchi@ism.ac.jp
AF: Institute of Statistical Mathematics, 4-6-7 Minami-Azabu, Tokyo, 106-8569, Japan
AB: In this study we statistically examine how large-scale field-aligned currents (FACs) and particle precipitation are related. We use magnetic-field and particle data obtained from the DMSP-F7 and F12-15 spacecraft during a few hundreds of thousands of auroral oval crossings at various local times. It is found that the average electron energy is well correlated with the FAC density, especially for upward FACs. This is what one might expect from the well-known relationship between the upward FAC and auroral acceleration (Knight relation), but the present result suggests that a similar relationship also holds on a larger scale, that is, for R1 and R2 currents. In certain MLT sectors the average ion energy is positively correlated with the FAC intensity, rather than with the FAC density, irrespective of the polarity of FACs, which might be puzzling from the viewpoint of the M-I coupling. This result, however, can be attributed to the fact that both the FAC intensity and the average energy of magnetospheric ions are correlated with geomagnetic activity. We seek to examine systematically the relationship between the FAC density/intensity and the average energy and energy flux of precipitation in terms of local time and particle species..
DE: 2704 Auroral phenomena (2407)
DE: 2716 Energetic particles: precipitating
DE: 2721 Field-aligned currents and current systems (2409)
DE: 2736 Magnetosphere/ionosphere interactions (2431)
DE: 2788 Magnetic storms and substorms (7954)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting