Wave-number spectra and intermittency in the terrestrial foreshock region

Abstract

Wave-number spectra of magnetic field fluctuations are directly determined in the terrestrial foreshock region (upstream of a quasiparallel collisionless shock wave) using four-point Cluster spacecraft measurements. The spectral curve is characterized by three ranges reminiscent of turbulence: energy injection, inertial, and dissipation range. The spectral index for the inertial range spectrum is close to Kolmogorov’s slope, -5/3. On the other hand, the fluctuations are highly anisotropic and intermittent perpendicular to the mean magnetic field direction. These results suggest that the foreshock is in a weakly turbulent and intermittent state in which parallel propagating Alfvén waves interact with one another, resulting in the phase coherence or the intermittency.

BibTeX
@article{id909,
  author = {Narita, Y. and Glassmeier, K. and Treumann, R.},
  journal = {Physical Review Letters},
  language = {en},
  number = {19},
  title = {Wave-number spectra and intermittency in the terrestrial foreshock region},
  volume = {79},
  year = {2006},
}
EndNote
%O Journal Article
%A Narita, Y.
%A Glassmeier, K.
%A Treumann, R.
%J Physical Review Letters
%G en
%N 19
%T Wave-number spectra and intermittency in the terrestrial foreshock region
%V 79
%D 2006