HR: 13:55h
AN: NG33A-02 [Abstracts]
TI: Radial (L) profiles of MHD wave power and energetic electron flux during high-speed streams: dependence on IMF Bz
AU: Koepke, M
EM: mark.koepke@mail.wvu.edu
AF: West Virginia University, Department of Physics
Hodges Hall
Box 6315, Morgantown, WV 26506-6315,
AU: * Vassiliadis, D
EM: dimitris.vassiliadis@mail.wvu.edu
AF: West Virginia University, Department of Physics
Hodges Hall
Box 6315, Morgantown, WV 26506-6315,
AU: Baker, D
EM: daniel.baker@lasp.colorado.edu
AF: University of Colorado, LASP
1234 Innovation Drive, Boulder, CO 80309,
AU: Weigel, R
EM: rweigel@gmu.edu
AF: George Mason University, Department of Computer and Data Sciences
Research 1 Bldg, Fairfax, VA 22030-4444,
AU: Zhang, J
EM: jiez@scs.gmu.edu
AF: George Mason University, Department of Computer and Data Sciences
Research 1 Bldg, Fairfax, VA 22030-4444,
AU: Poomvises, W
EM: wpoomvis@gmu.edu
AF: George Mason University, Department of Computer and Data Sciences
Research 1 Bldg, Fairfax, VA 22030-4444,
AB:
During the passage of solar wind high-speed streams, normally characterized by a weak IMF, historic
observations [e.g. Rostoker et al., JGR 1998] have shown that a peak of both ULF wave power and electron flux is
formed at high L (5-6), measurable from geosynchronous orbit (6.6). Recurrence of the streams leads to a driven
oscillation in the magnetospheric field and particle distributions between an excited and a quiet state, with a delay
time of 2 days following the solar wind speed.
Here we show that, in the presence of Southward IMF Bz, the new peak will form instead at low L (~3) and in
some events within the slot L range (2-3). In addition to the change in the magnetospheric configuration resulting
from a steady IMF BSouth, it is the fluctuations in the field power and therefore in the wave-particle interaction that
are significant in changing the wave power and particle flux profiles. The timescale for those interactions is
reduced from 2 days to several hours or tens of minutes. The effect is compared both to effects during low-IMF
high-speed streams and to interplanetary coronal mass ejections (Vassiliadis et al., submitted to GRL).
DE: 4400 NONLINEAR GEOPHYSICS (3200, 6944, 7839)
SC: Nonlinear Geophysics [NG]
MN: 2007 Fall Meeting