|
|
 |
|
|
Ann. Geophys., 23, 3339-3349, 2005
www.ann-geophys.net/23/3339/2005/
© European Geosciences Union 2005
Statistical phase propagation and dispersion analysis of low frequency waves in the magnetosheath
S. Schäfer1, K.-H. Glassmeier1, Y. Narita1, K. H. Fornaçon1, I. Dandouras2, and M. Fränz3
1Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Germany
2Centre d’Etude Spatiale des Rayonnements, Toulouse, France
3Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany
Abstract. We present the results of a statistical analysis of low-frequency
fluctuations in the high latitude regions of the dayside magnetosheath
using CLUSTER as a wave telescope. Magnetic field observations are used to
determine wave propagation directions and wave numbers for selected
frequencies. Using observations of the plasma flow velocity we correct for
the Doppler shift, in order to calculate frequencies and phase velocities
in the plasma rest frame. This provides us with the possibility to perform
a statistical dispersion analysis and to investigate various wave
properties, such as the phase velocity and the propagation angle between
k and B. The analysis of dispersion distributions and
Friedrichs diagrams results in the identification of different wave
populations. We find a multiplicity of standing structures (mirror modes)
convected with the plasma flow and a large number of Alfvénic waves.
The results confirm previous magnetosheath wave studies, such as ISSE or AMPTE
spacecraft observations, but we also find a small number of mirror
mode-like waves that have propagation speeds up to the local Alfvén
velocity, quasi-perpendicular to the magnetic field.
Full Article in PDF (689 KB) |
|
|
