2016/11/24 by L. Z. Hadid, F. Sahraoui, K. H. Kiyani +5 · 1 citation
Physics and Astronomy · #physics.space-ph #astro-ph.EP #physics.plasm-ph
paper · pdf · doi:10.1088/2041-8205/813/2/l29
arxiv created 2016/11/24 · arxiv updated 2016/11/28
Low frequency turbulence in Saturn's magnetosheath is investigated using in-situ measurements of the Cassini spacecraft. Focus is put on the magnetic energy spectra computed in the frequency range ∼[10-4, 1]Hz. A set of 42 time intervals in the magnetosheath were analyzed and three main results that contrast with known features of solar wind turbulence are reported: 1) The magnetic energy spectra showed a ∼ f-1 scaling at MHD scales followed by an ∼ f-2.6 scaling at the sub-ion scales without forming the so-called inertial range; 2) The magnetic compressibility and the cross-correlation between the parallel component of the magnetic field and density fluctuations C(δn,δB||) indicates the dominance of the compressible magnetosonic slow-like modes at MHD scales rather than the Alfvén mode; 3) Higher order statistics revealed a monofractal (resp. multifractal) behaviour of the turbulent flow downstream of a quasi-perpendicular (resp. quasi-parallel) shock at the sub-ion scales. Implications of these results on theoretical modeling of space plasma turbulence are discussed.