A Model for the MHD Turbulence in the Earth’s Plasma Sheet: Building Computer Simulations

Borovsky, Joseph E.

doi:10.1007/1-4020-2768-0_13

Cited by 7 publications

(4 citation statements)

References 84 publications

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“…To determine the necessary elongation of the simulation volume in the z direction, we consider the correlation length of the velocity field in each direction. We measure a correlation length of the velocity field in the z direction, L c,|| , that is larger than in the x and y directions, in agreement with previous studies, (e.g., Boldyrev, 2005;Chandran, 2008;Cho et al, 2002). To accommodate this larger L c,|| within our simulation volume, we elongate the simulation volume in the z direction, so that the condition on the box length in the z direction L z ≫ L c,|| is satisfied.…”

Section: Direct Numerical Simulations For Lagrangian Single-particle Diffusion and Two-particle Dispersionsupporting

confidence: 86%

“…In the solar wind, ion foreshock, and magnetosheath, ranges have been reported such that the macroscopic magnetic field is between 1 and 2.5 times the RMS fluctuations (Zimbardo et al, 2010). In Earth's plasma sheet the macroscopic magnetic field is on the order of two times the RMS fluctuations of the turbulent magnetic field (

B_{0} \approx 2 B_{sans-serifR sans-serifM sans-serifS}

) (Borovsky, 2005). In the magnetotail, observational data indicate that the magnetic field is stronger, between three and five times the RMS fluctuations (see Table 1 of Zimbardo et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Lagrangian Statistics for Dispersion in Magnetohydrodynamic Turbulence

2020

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Measurements in the heliosphere and high-resolution fluid simulations give clear indications for the anisotropy of plasma turbulence in the presence of magnetic fields. How this anisotropy affects transport processes like diffusion and dispersion remains an open question. The first efforts to characterize Lagrangian single-particle diffusion and two-particle dispersion in incompressible magnetohydrodynamic (MHD) turbulence were performed a decade ago. We revisit those pioneering results through updated simulations performed at higher Reynolds number. We present new investigations that use the dispersion of many Lagrangian tracer particles to examine the extremes of dispersion and the anisotropy in direct numerical simulations. We then point out directions in which Lagrangian statistics need to be developed to address the fundamental problem of anisotropic MHD turbulence and transport in solar and stellar winds.

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Section: Direct Numerical Simulations For Lagrangian Single-particle Diffusion and Two-particle Dispersionsupporting

confidence: 86%

B_{0} \approx 2 B_{sans-serifR sans-serifM sans-serifS}

) (Borovsky, 2005). In the magnetotail, observational data indicate that the magnetic field is stronger, between three and five times the RMS fluctuations (see Table 1 of Zimbardo et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Lagrangian Statistics for Dispersion in Magnetohydrodynamic Turbulence

2020

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“…In fluid dynamics, all high‐Reynolds‐number flows are turbulent [ Schlichtng , 1979; Novopashin and Muriel , 2002; Ben‐Dov and Cohen , 2007]. Determining the Reynolds number of a plasma flow in the magnetosphere is complicated owing to electrodynamic coupling of the plasma to the ionosphere, which can act at a distance on magnetospheric flows in addition to internal “fluid” processes [ Borovsky and Funsten , 2003; Borovsky , 2004]. Treating the internal fluid processes first, the Reynolds number of the drainage‐plume flow is estimated as follows.…”

Section: Discussionmentioning

confidence: 99%

A statistical look at plasmaspheric drainage plumes

2008

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[1] The properties of plasmaspheric drainage plumes are examined using cold-plasma measurements in geosynchronous orbit. During high-speed stream-driven storms, 210 plume crossings are collected and statistically analyzed. Plumes that persist for 4 days are common, which was the duration of our search. Plumes weaken with age, becoming narrower in local time with plasma that becomes less dense. Cold-plasma flow velocities are sunward in the plumes, with flow speeds decreasing as the storms progress. Plumes transfer typically 2 Â 10 26 ions/sec (1.2 ton/hr of protons) when they are young, and the rate of transport decreases with plume age. A total of approximately 2 Â 10 31 ions (34 tons of protons) are transported via plumes in the life of a storm. About half of the outer plasmasphere is drained in the first 20 hours of a storm. Large density fluctuations in the plumes indicate that the drainage plumes are lumpy, and large velocity fluctuations of the plasma flow indicate that the drainage plumes may be turbulent. Because of their persistence, drainage plumes are anticipated to be a regular feature of any ongoing geomagnetic storm.

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“…Evidence of turbulence in the Earth's magnetosphere has been found by various spacecraft observations (Nykyri et al, 2006;Sundkvist et al, 2005;Zimbardo et al, 2008), and several authors have studied magnetospheric MHD turbulence (see, e.g., Borovsky, 2004;Hwang et al, 2011;El-Alaoui et al, 2012). However, given the large number of degrees of freedom, simulation of turbulent systems has a large computational cost, which has led to the development of analytical models, which, while sharing statistical properties of the systems under study, depend only on a few degrees of freedom (Chapman et al, 1998;Valdivia et al, 2006).…”

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confidence: 99%

Evolution of fractality in space plasmas of interest to geomagnetic activity

Muñoz

Domínguez

Valdivia

et al. 2018

Nonlin. Processes Geophys.

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Abstract. We studied the temporal evolution of fractality for geomagnetic activity, by calculating fractal dimensions from the Dst data and from a magnetohydrodynamic shell model for turbulent magnetized plasma, which may be a useful model to study geomagnetic activity under solar wind forcing. We show that the shell model is able to reproduce the relationship between the fractal dimension and the occurrence of dissipative events, but only in a certain region of viscosity and resistivity values. We also present preliminary results of the application of these ideas to the study of the magnetic field time series in the solar wind during magnetic clouds, which suggest that it is possible, by means of the fractal dimension, to characterize the complexity of the magnetic cloud structure.

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A Model for the MHD Turbulence in the Earth’s Plasma Sheet: Building Computer Simulations

Cited by 7 publications

References 84 publications

Lagrangian Statistics for Dispersion in Magnetohydrodynamic Turbulence

Lagrangian Statistics for Dispersion in Magnetohydrodynamic Turbulence

A statistical look at plasmaspheric drainage plumes

Evolution of fractality in space plasmas of interest to geomagnetic activity

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