3-dimensional anisotropic k-spectra of turbulencein the bow shock region

【摘要】：With observations of the Cluster satellites of short separations (about 100 km) we use the k-filtering method to get 3-dimensional (3D) k-spectra of magnetic turbulence in the upstream and downstream of the bow shock region. Based on the events during the year of 2002, we obtain the statistical characteristic of the 3-D anisotropy of magnetic field energy distribution and the power index of k- spectra. The energy distribution shows that the fluctuations should be composed of two populations, i.e. the major population extending toward the perpendicular coordinate and the minor one extending along the coordinate parallel to mean magnetic field. The power index of k-spectra is close to -2.0 in the upstream of the bow shock region, differently in the downstream of the bow shock the power index is close to -3/2 which is predicted by Iroshnikov and Kraichnan. Finially, we discuss the difference of the power index.