Phase coherence of foreshock MHD waves: wavelet analysis

Authors: Koga, Daiki; Hada, Tohru

Source: Space Science Reviews, Volume 107, Numbers 1-2, April 2003 , pp. 495-498(4)

Publisher: Springer

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Abstract:

The earth's foreshock is a region where particularly large amplitude MHD waves are commonly observed. They exhibit various waveforms, suggesting that nonlinear interaction between the waves is in progress. In a previous paper (Hada et al., 2003) we have introduced a method to quantitatively evaluate the strength of phase coherence among the waves from a given time series data. Here we further develop our method by applying wavelet filtering technique. From the analysis it was found that, although the turbulence is consisted of waves with a wide range of plasma rest frame frequencies, only those frequencies lower than the ion gyrofrequency are responsible for generating the phase coherence.

Keywords: MHD turbulence; phase coherence; wavelet analysis

Document Type: Research article

DOI: http://dx.doi.org/10.1023/A:1025510225311

Publication date: 2003-04-01