Search Publications
Revisiting Algorithms for Generating Surrogate Time Series
Papadakis, I. E.; Brinkmann, W.; Gliozzi, M. +1 more
The method of surrogates is one of the key concepts of nonlinear data analysis. Here, we demonstrate that commonly used algorithms for generating surrogates often fail to generate truly linear time series. Rather, they create surrogate realizations with Fourier phase correlations leading to nondetections of nonlinearities. We argue that reliable s…
Nonaxisymmetric Anisotropy of Solar Wind Turbulence as a Direct Test for Models of Magnetohydrodynamic Turbulence
Chapman, S. C.; Turner, A. J.; Gogoberidze, G.
Single point spacecraft observations of the turbulent solar wind flow exhibit a characteristic nonaxisymmetric anisotropy that depends sensitively on the perpendicular power spectral exponent. We use this nonaxisymmetric anisotropy as a function of wave vector direction to test models of MHD turbulence. Using Ulysses magnetic field observations in…
Coupling Between Whistler Waves and Ion-Scale Solitary Waves: Cluster Measurements in the Magnetotail During a Substorm
Le Contel, O.; Cornilleau-Wehrlin, N.; Tenerani, A. +4 more
We present a new model of self-consistent coupling between low frequency, ion-scale coherent structures with high frequency whistler waves in order to interpret Cluster data. The idea relies on the possibility of trapping whistler waves by inhomogeneous external fields where they can be spatially confined and propagate for times much longer than t…
Comment on ``Effect of Current Sheets on the Solar Wind Magnetic Field Power Spectrum from the Ulysses Observation: From Kraichnan to Kolmogorov Scaling''
Perri, S.; Carbone, V.
A Comment on the Letter by G. Li et al., Phys. Rev. Lett.PRLTAO0031-9007 106, 125001 (2011)10.1103/PhysRevLett.106.125001. The authors of the Letter offer a Reply.
Gyrokinetic Simulations of Solar Wind Turbulence from Ion to Electron Scales
Quataert, E.; Howes, G. G.; Schekochihin, A. A. +4 more
A three-dimensional, nonlinear gyrokinetic simulation of plasma turbulence resolving scales from the ion to electron gyroradius with a realistic mass ratio is presented, where all damping is provided by resolved physical mechanisms. The resulting energy spectra are quantitatively consistent with a magnetic power spectrum scaling of k-2.8
Plasma Jet Braking: Energy Dissipation and Nonadiabatic Electrons
André, M.; Vaivads, A.; Owen, C. J. +2 more
We report in situ observations by the Cluster spacecraft of wave-particle interactions in a magnetic flux pileup region created by a magnetic reconnection outflow jet in Earth’s magnetotail. Two distinct regions of wave activity are identified: lower-hybrid drift waves at the front edge and whistler-mode waves inside the pileup region. The whistle…
Electron Temperature Gradient Scale at Collisionless Shocks
Krasnoselskikh, Vladimir; Schwartz, Steven J.; Henley, Edmund +1 more
Shock waves are ubiquitous in space and astrophysics. They transform directed flow energy into thermal energy and accelerate energetic particles. The energy repartition is a multiscale process related to the spatial and temporal structure of the electromagnetic fields within the shock layer. While large scale features of ion heating are known, the…
Kinetic Structure of the Electron Diffusion Region in Antiparallel Magnetic Reconnection
Egedal, J.; Daughton, W.; Chen, L. -J. +2 more
Strong electron pressure anisotropy has been observed upstream of electron diffusion regions during reconnection in Earth’s magnetotail and kinetic simulations. For collisionless antiparallel reconnection, we find that the anisotropy drives the electron current in the electron diffusion region, and that this current is insensitive to the reconnect…
Anisotropic Third-Moment Estimates of the Energy Cascade in Solar Wind Turbulence Using Multispacecraft Data
Dasso, S.; Matthaeus, W. H.; Wan, M. +2 more
The first direct determination of the inertial range energy cascade rate, using an anisotropic form of Yaglom’s law for magnetohydrodynamic turbulence, is obtained in the solar wind with multispacecraft measurements. The two-point mixed third-order structure functions of Elsässer fluctuations are integrated over a sphere in magnetic field-aligned …
Effect of Current Sheets on the Solar Wind Magnetic Field Power Spectrum from the Ulysses Observation: From Kraichnan to Kolmogorov Scaling
Li, G.; Hu, Q.; Qin, G. +1 more
The MHD turbulence theory developed by Iroshnikov and Kraichnan predicts a k-1.5 power spectrum. Solar wind observations, however, often show a k-5/3 Kolmogorov scaling. Based on 3 years worth of Ulysses magnetic field data where over 28 000 current sheets are identified, we propose that the current sheet is the cause of the …