HR: 0830h
AN: SM41C-0587    [PDF]
TI: Observations of Particle Injection and Loss Processes in the Earth's Radiation Belts
AU: * Dotan, Y
EM: yaniv.dotan@notes.aero.org
AF: The Aerospace Corporation, P.O. BOX 92957 MS M2-255, Los Angeles, CA 90009-2957 United States
AU: Thorne, R M
EM: rmt@atmos.ucla.edu
AF: UCLA, Department of Atmospheric Sciences, 7127 MS P.O. BOX 951565 405 Hilgaurd ave, Los Angeles, CA 90095-1565 United States
AU: Fennell, J F
EM: joseph.f.fennell@notes.aero.org
AF: The Aerospace Corporation, P.O. BOX 92957 MS M2-255, Los Angeles, CA 90009-2957 United States
AU: Fennell, J F
EM: joseph.f.fennell@notes.aero.org
AF: University of New Hampshire, 410 Morse Hall, Durham, NH 03824 United States
AU: Jordanova, V K
EM: vania.jordanova@unh.edu
AF: University of New Hampshire, 410 Morse Hall, Durham, NH 03824 United States
AU: McNab, M C
EM: michael.c.mcnab@notes.aero.org
AF: The Aerospace Corporation, P.O. BOX 92957 MS M2-255, Los Angeles, CA 90009-2957 United States
AB: CEPPAD IPS data of positive ion pitch-angle distributions (PADs) with energies of 15-234 keV during the 1997 geomagnetic storms of January 10 and May 15 were analyzed for injection, scattering, and precipitation. These events were chosen for the particular orientation of the POLAR spacecraft orbit, which roughly covers the dusk-dawn and noon-midnight meridians respectively. During the course of the storms, the data showed extensive isotropic PADs over the dusk-to-midnight MLT sectors for L-shells between 5-10, indicating strong pitch-angle diffusion. Filled loss cones were also observed associated with the isotropic distributions, signifying the presence of intense precipitation in these regions. These findings were corroborated with data from Polar's CAMMICE MICS instrument. Tsyganenko's T01 model was used to trace the field line of in situ observations and derive mirror points, equatorial crossing points, and radii of curvature of the field line. Mappings of in situ PADs into the equatorial plane were then compared with magnetospheric model simulations. At lower L-shells the observed strong diffusion and precipitation was found to be in agreement with model simulations, which incorporate wave-particle interaction loss processes. However the radial profiles of trapped and precipitated particles as well as field line curvatures, points to a wide scattering source at higher L. These finding are interpreted as the signature of non-adiabatic pitch-angle scattering in the dusk and night side current-sheet. Unlike pitch-angle scattering induced by wave activity, which is a local effect at low L-shells, current-sheet scattering is associated with a much wider and extensive region.
DE: 2716 Energetic particles, precipitating
DE: 2720 Energetic particles, trapped
DE: 2778 Ring current
DE: 2788 Storms and substorms
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting