Correlations Between Coherent Waveforms and Particle Distribution Functions Observed in the Near-Earth Magnetotail by the Wind Spacecraft

M. O. Fillingim1, C. Salem1, A. Mangeney2, and S. D. Bale1

1Space Sciences Laboratory, University of California, Berkeley
2Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique (LESIA), Observatoire de Paris, Meudon

Presented at the 2006 Western Pacific Geophysics Meeting, Beijing, China, 24 - 27 July 2006


Abstract

We present an analysis of simultaneously observed electromagnetic waveforms and ion and electron distribution functions measured by the WAVES and the 3-D Plasma experiments onboard the Wind spacecraft during a perigee pass through the near-Earth magnetotail. The WAVES experiment is composed of state-of-the-art high-time resolution spectral receivers and waveform analyzers sampling electric and magnetic signals up to 120000 samples/sec. The 3-D Plasma experiment provides measurements of the full three-dimensional ion and electron distribution functions covering energies from 10 eV to 20 keV. The dataset analyzed here comes from one Wind perigee pass through the magnetotail at radial distances between 5 and 8 Earth radii during a magnetically quiet period. Analysis of the data show several types of coherent waveforms between 50 Hz and a few hundred kHz such as quasi-monochromatic waves with frequencies close to the electron cyclotron frequency, solitary-like structures, low frequency whistlers, electron Bernstein waves, as well as coherent burts of Langmuir waves or upper-hybrid waves. In addition very peculiar particle distribution functions are observed at times of wave activity. We discuss the nature and detailed properties of the observed wavemodes. We also look for correlations between the waves and particular features in the ion and electron distribution functions in an attempt to identify the source(s) of the waves and understand the plasma micro-instability process(es) leading to these coherent fluctuations. Correlations between wave activity and auroral and magnetospheric activity are also investigated.



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Matt Fillingim
matt at ssl dot berkeley dot edu
University of California, Berkeley
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