HR: 18:05h
AN: SM24A-08 INVITED     [Abstracts]
TI: Energisation of Radiation Belt Electrons by ULF waves: Role of the Plasmapause and Heavy Ions
AU: * Mann, I R
EM: imann@phys.ualberta.ca
AF: University of Alberta, Mailstop 615, Department of Physics, University of Alberta, Edmonton, AB T6G 2G7, Canada
AU: Ozeke, L G
EM: lozeke@phys.ualberta.ca
AF: University of Alberta, Mailstop 615, Department of Physics, University of Alberta, Edmonton, AB T6G 2G7, Canada
AU: Degeling, A
EM: degeling@phys.ualberta.ca
AF: University of Alberta, Mailstop 615, Department of Physics, University of Alberta, Edmonton, AB T6G 2G7, Canada
AU: Rankin, R
EM: rankin@phys.ualberta.ca
AF: University of Alberta, Mailstop 615, Department of Physics, University of Alberta, Edmonton, AB T6G 2G7, Canada
AU: Dent, Z C
EM: zdent@phys.ualberta.ca
AF: University of Alberta, Mailstop 615, Department of Physics, University of Alberta, Edmonton, AB T6G 2G7, Canada
AB: Recent theoretical studies have demonstrated how ULF waves can energise radiation belt electrons via inward transport through the drift-bounce resonance mechanism. The long-timescale behaviour is usually described as a diffusive inward transport in ULF wave fields. Given that ULF wave propagation is governed by the ambient mass density, the penetration of ULF wave fields to low-L in the radiation belts is influenced by the location of the plasmapause as well as heavy ion populations. We show examples from Halloween 2003 storms which demonstrate that changes to the background Alfven continnum, most likely resulting from the injection of heavy ions outside the plasmapause, can generate conditions preferential to the penetration of ULF power deep into the radation belts. Modelling of the drift resonant interaction demonstrates how time-limited ULF wavetrains can also lead to coherent electron transport on timescales much faster then expected through diffusion. During stormtimes, the ring current also penetrates to the heart of the outer radiation belt and can become dominated by 100's keV O+ ions outside the depleted plasmapause. We show that it is possible for moderately high azimuthal wavenumber (m) ULF waves to be driven by drift-bounce resonanace mechansism with these energetic ions. Under conditions of a depleted plasmasphere, these ring current ion excited ULF waves can resonate with radiation belt electrons. This provides an exciting potential pathway for the transfer of energy from the storm-time ring current into the radiation belts via the intermediary of ULF waves.
DE: 2730 Magnetosphere: inner
DE: 2752 MHD waves and instabilities (2149, 6050, 7836)
DE: 2772 Plasma waves and instabilities (2471)
DE: 2774 Radiation belts
DE: 2788 Magnetic storms and substorms (7954)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Joint Assembly