Discovery of very large amplitude whistler-mode waves in Earth's radiation belts

C. Cattell (1) , J. R. Wygant (1) , Keith Goetz (1) , K. Kersten (1) , P. J. Kellogg (1) , T. Von Rosenvinge (2) , Stuart D. Bale (3) , I. Roth (4) , M. Temerin (4) , M. K. Hudson (5) , R. A. Mewaldt (6) , M. Wiedenbeck (7) , Milan Maksimovic (8, 9) , R. Ergun (10) , M. Acuña (2) , Christopher T. Russell (11)

1 School of Physics and Astronomy, University of Minnesota
2 GSFC - NASA Goddard Space Flight Center
3 Department of Physics, Le Conte Hall, University of California
4 SSL - Space Sciences Laboratory [Berkeley]
5 Department of Physics, Dartmouth College
6 Downs Laboratory, California Institute of Technology
7 JPL - Jet Propulsion Laboratory
8 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
9 Physique des plasmas
10 LASP - Laboratory for Atmospheric and Space Physics [Boulder]
11 Institute for Geophysics and Planetary Physics, University of California, Los Angeles

During a passage through the Earth's dawn-side outer radiation belt, whistler-mode waves with amplitudes up to more than ~240 mV/m were observed by the STEREO S/WAVES instrument. These waves are an order of magnitude larger than previously observed for whistlers in the radiation belt. Although the peak frequency is similar to whistler chorus, there are distinct differences from chorus, in addition to the larger amplitudes, including the lack of drift in frequency and the oblique propagation with a large longitudinal electric field component. Simulations show that these large amplitude waves can energize an electron by the order of an MeV in less than 0.1s, explaining the rapid enhancement in electron intensities observed between the STEREO-B and STEREO-A passage during this event. Our results show that the usual theoretical models of electron energization and scattering via small-amplitude waves, with timescales of hours to days, may be inadequate for understanding radiation belt dynamics.

Domaines: Astrophysique [astro-ph]

C. Cattell, J. R. Wygant, Keith Goetz, K. Kersten, P. J. Kellogg, et al.. Discovery of very large amplitude whistler-mode waves in Earth's radiation belts. Geophysical Research Letters, 2008, 35, pp.01105. ⟨10.1029/2007GL032009⟩. ⟨hal-03785427⟩