Anisotropic Turbulent Spectra in the Terrestrial Magnetosheath as Seen by the Cluster Spacecraft
Publication date: 24 February 2006
Authors: Sahraoui, F. et al.
Journal: Physical Review Letters
Volume: 96
Year: 2006
Copyright: The American Physical Society
DOI: 10.1103/PhysRevLett.96.075002
Here we report the first three-dimensional spatial spectrum of the low frequency magnetic turbulence obtained from the four Cluster spacecraft in the terrestrial magnetosheath close to the magnetopause. We show that the turbulence is compressible and dominated by mirror structures, its energy is injected at a large scale k × rho ~ 0.3 (l~2000 km) via a mirror instability well predicted by linear theory, and cascades nonlinearly and unexpectedly up to k × rho ~ 3.5 (l~150 km), revealing a new power law in the inertial range not predicted by any turbulence theory, and its strong anisotropy is controlled by the static magnetic field and the magnetopause normal.