HR: 17:30h
AN: SM14B-07    [Abstracts]
TI: Observations of Very High Amplitudes of Whistler-Mode Chorus: Consequences for Nonlinear Trapping of Energetic Electrons in the Outer Radiation Belt
AU: * Santolik, O
EM: os@ufa.cas.cz
AF: IAP ASCR, Bocni II 1401, Prague, 14131, Czech Republic
AU: * Santolik, O
EM: os@ufa.cas.cz
AF: Charles University, V Holesovickach 2, Prague, 18000, Czech Republic
AU: Gurnett, D A
EM: donald-gurnett@uiowa.edu
AF: University of Iowa, Department of Physics & Astronomy, Iowa City, IA 52242, United States
AU: Pickett, J S
EM: pickett@uiowa.edu
AF: University of Iowa, Department of Physics & Astronomy, Iowa City, IA 52242, United States
AB: Whistler mode chorus has recently regained attention as a possible agent in acceleration of electrons to relativistic energies in the outer Van Allen belt. As theoretical and simulation studies show, sufficiently high amplitudes of chorus wave packets are needed. We present analysis of observations of high resolution magnetic field waveforms by the four Cluster spacecraft. The results show that chorus can reach amplitudes of several nT but only for a very small fraction of wave packets. We systematically analyze a large data set of measured waveforms to verify signatures of nonlinear wave trapping of energetic electrons. Fine structure embedded in the chorus elements mainly reflects simultaneous presence of waves at different frequencies (sidebands) although separate wave packets are also observed. The observed frequency differences (time scales of subpackets) as a function of wave amplitude are compared to theoretical estimates of the nonlinear trapping frequency.
UR: http://os.matfyz.cz/papers/agu2007/
DE: 2772 Plasma waves and instabilities (2471)
DE: 6939 Magnetospheric physics (2700)
DE: 6984 Waves in plasma (7867)
DE: 7839 Nonlinear phenomena (4400, 6944)
DE: 7867 Wave/particle interactions (2483, 6984)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting