Generation of Bernstein waves by ion shell distributions in the auroral region

P. Janhunen (1) , A. Olsson (2) , A. Vaivads (2) , W. K. Peterson (3)

1 FMI - Finnish Meteorological Institute
2 IRF - Swedish Institute of Space Physics [Kiruna]
3 LASP - Laboratory for Atmospheric and Space Physics [Boulder]

Hot ion shell distributions could possibly contain enough free energy for waves that could power electron energisation above auroral inverted-V regions. Using both linear theory (WHAMP) and two-dimensional electrostatic simulations, we show that ion shell distributions can cause unstable ion Bernstein mode emissions with high temporal growth rates, as well as perpendicular and parallel e-folding distances, that are in accordance with the tranverse dimensions of auroral arcs and the parallel size of the energisation region, respectively. The phase velocities of the waves are in the proper range to give parallel energisation to electrons with a Landau resonance. The simulation shows that about 90% of the energy goes into electrons and 10% goes into cold ion perpendicular heating. An electron heating rate of ~ 80 eV/s is obtained.

Domaines: Océan, Atmosphère; Sciences de la Terre

P. Janhunen, A. Olsson, A. Vaivads, W. K. Peterson. Generation of Bernstein waves by ion shell distributions in the auroral region. Annales Geophysicae, 2003, 21 (4), pp.881-891. ⟨hal-00317040⟩