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www.nonlin-processes-geophys.net/14/361/2007/
doi:10.5194/npg-14-361-2007
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Observations of linear and nonlinear processes in the foreshock wave evolution
1Institute of Geophysics and Extraterrestrial Physics, Technical University of Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany
2Max-Planck-Institute for Solar System Research, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany
3Department of Earth System Science and Technology, Kyushu University, 816-8580, Kasuga, Japan
Abstract. Waves in the foreshock region are studied on the basis of a hypothesis that the linear process first excites the waves and further wave-wave nonlinearities distribute scatter the energy of the primary waves into a number of daughter waves. To examine this wave evolution scenario, the dispersion relations, the wave number spectra of the magnetic field energy, and the dimensionless cross helicity are determined from the observations made by the four Cluster spacecraft. The results confirm that the linear process is the ion/ion right-hand resonant instability, but the wave-wave interactions are not clearly identified. We discuss various reasons why the test for the wave-wave nonlinearities fails, and conclude that the higher order statistics would provide a direct evidence for the wave coupling phenomena.
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Citation: Narita, Y., Glassmeier, K.-H., Fränz, M., Nariyuki, Y., and Hada, T.: Observations of linear and nonlinear processes in the foreshock wave evolution, Nonlin. Processes Geophys., 14, 361-371, doi:10.5194/npg-14-361-2007, 2007. Bibtex EndNote Reference Manager XML
