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GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L01105, doi:10.1029/2007GL032009, 2008

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

C. Cattell

School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota, USA


J. R. Wygant

School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota, USA


K. Goetz

School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota, USA


K. Kersten

School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota, USA


P. J. Kellogg

School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota, USA


T. von Rosenvinge

NASA Goddard Space Flight Center, Greenbelt, Maryland, USA


S. D. Bale

Space Sciences Laboratory, University of California, Berkeley, California, USA
Department of Physics, University of California, Berkeley, California, USA


I. Roth

Space Sciences Laboratory, University of California, Berkeley, California, USA


M. Temerin

Space Sciences Laboratory, University of California, Berkeley, California, USA


M. K. Hudson

Department of Physics, Dartmouth College, Hanover, New Hampshire, USA


R. A. Mewaldt

Downs Laboratory, California Institute of Technology, Pasadena, California, USA


M. Wiedenbeck

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA


M. Maksimovic

Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Observatoire de Paris, Meudon, France


R. Ergun

Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado, USA


M. Acuna

NASA Goddard Space Flight Center, Greenbelt, Maryland, USA


C. T. Russell

Institute for Geophysics and Planetary Physics, University of California, Los Angeles, California, USA


Abstract

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.

Received 13 September 2007; accepted 6 December 2007; published 12 January 2008.

Keywords: whistler waves; electron energization; radiation belt.

Index Terms: 2774 Magnetospheric Physics: Radiation belts; 2772 Magnetospheric Physics: Plasma waves and instabilities (2471); 7846 Space Plasma Physics: Plasma energization; 7867 Space Plasma Physics: Wave/particle interactions (2483, 6984).


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Citation: Cattell, C., et al. (2008), Discovery of very large amplitude whistler-mode waves in Earth's radiation belts, Geophys. Res. Lett., 35, L01105, doi:10.1029/2007GL032009.