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arXiv · 1611.08245

Nature of the MHD and kinetic scale turbulence in the magnetosheath of Saturn: Cassini observations

L. Z. Hadid·F. Sahraoui·K. H. Kiyani·A. Retinò·R. Modolo·P. Canu·A. Masters·M. K. Dougherty
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Abstract

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 $\sim[10^{-4}, 1]$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 $\sim f^{-1}$ scaling at MHD scales followed by an $\sim f^{-2.6}$ 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.

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L. Z. Hadid, F. Sahraoui, K. H. Kiyani, A. Retinò, R. Modolo, P. Canu, A. Masters, M. K. Dougherty. 2016-11-24. Nature of the MHD and kinetic scale turbulence in the magnetosheath of Saturn: Cassini observations. https://doi.org/10.1088/2041-8205%2F813%2F2%2Fl29

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