Stationarity of magnetohydrodynamic fluctuations in the solar wind

Matthaeus, W. H.; Goldstein, M. L.

doi:10.1029/ja087ia12p10347

Cited by 139 publications

(114 citation statements)

References 17 publications

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“…Those broadband spectra in frequency are believed to be inherited from the Kolmogorov type spectra of turbulence in wavenumber. A ''frozen-in'' hypothesis can be invoked to relate both type of spectra [Matthaeus and Goldstein, 1982]. Estimated high Reynolds numbers further support the turbulent scenario.…”

Section: Introductionmentioning

confidence: 87%

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Discrete modes and turbulence in a wave‐driven strongly magnetized plasma

Dmitruk

Matthaeus

Lanzerotti³

2004

Geophysical Research Letters

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[1] We show the coexistence of discrete modes and t u r b u l e n c e i n n u m e r i c a l e x p e r i m e n t s o f magnetohydrodynamics with a strong background magnetic field. The particular system we consider is a model of an open magnetic region which we have previously used in coronal heating studies. In the simulations shown here, Alfven waves at discrete frequencies with values corresponding to solar g-modes and p-modes are injected at the boundary (although the question of how those modes could generate Alfven waves is not addressed). Numerical probes are used to compute the magnetic field fluctuations at the output. The frequency spectra obtained from those probes are broadband, but with peaks at the driving frequencies. The perpendicular (to the mean magnetic field) wavenumber energy spectrum is of a turbulent Kolmogorov-like type, and formation of small scale structures is observed. This shows, numerically, the possibility of persistence of discrete modes in a turbulent system.

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Section: Introductionmentioning

confidence: 87%

“…Magnetohydrodynamic (MHD) turbulence is observed in many space and astrophysical plasmas, like the solar wind [Coleman, 1968;Burlaga and Mish, 1987;Matthaeus and Goldstein, 1982;Goldstein et al, 1995;Marsch et al, 1996]. Evidence is shown on the form of continuous (power law) frequency spectra of magnetic field fluctuation time series.…”

Section: Introductionmentioning

confidence: 99%

Discrete modes and turbulence in a wave‐driven strongly magnetized plasma

Dmitruk

Matthaeus

Lanzerotti³

2004

Geophysical Research Letters

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“…Nevertheless, we went beyond the ergodicity test and a considerable more restrictive condition was imposed on the data samples before and after the CIR, where¯uctuations are clearly larger in the quasi-parallel direction than in the perpendicular direction. The condition corresponds to¯uctu-ations that are completely uncorrelated for times t > T 0 , where the autocorrelation function is R(t > T 0 ) » 0, and may be expressed as: Matthaeus and Goldstein, 1982b).…”

Section: Resultsmentioning

confidence: 99%

“…The test of ergodicity as represented by the autocorrelation function being a Lanczos type function guarantees that the time average of the IMF data samples over an interval T ([B] T ) converge to the ensemble average b, where b is independent of time (Matthaeus and Goldstein, 1982b). Nevertheless, we went beyond the ergodicity test and a considerable more restrictive condition was imposed on the data samples before and after the CIR, where¯uctuations are clearly larger in the quasi-parallel direction than in the perpendicular direction.…”

Section: Resultsmentioning

confidence: 99%

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Study of the magnetic turbulence in a corotating interaction region in the interplanetary medium

Valdés-Galicia

Caballero

1999

Ann Geophysicae

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Abstract. We study the geometry of magnetic¯uctua-tions in a CIR observed by Pioneer 10 at 5 AU between days 292 and 295 in 1973. We apply the methodology proposed by Bieber et al. to make a comparison of the relative importance of two geometric arrays of vector propagation of the magnetic ®eld¯uctuations: slab and two-dimensional (2D). We found that inside the studied CIR this model is not applicable due to the restrictions imposed on it. Our results are consistent with Alfvenic uctuations propagating close to the radial direction, con®rming Mavromichalaki et al.'s ®ndings. A mixture of isotropic and magnetoacoustic waves in the region before the front shock would be consistent with our results, and a mixture of slab/2D and magnetoacoustic waves in a region after the reverse shock. We base the latter conclusions on the theoretical analysis made by Kunstmann. We discuss the reasons why the composite model can not be applied in the CIR studied although the¯uctuations inside it are two dimensional.

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Active current sheets and candidate hot flow anomalies upstream of Mercury's bow shock

et al. 2014

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Hot flow anomalies (HFAs) represent a subset of solar wind discontinuities interacting with collisionless bow shocks. They are typically formed when the normal component of the motional (convective) electric field points toward the embedded current sheet on at least one of its sides. The core region of an HFA contains hot and highly deflected ion flows and rather low and turbulent magnetic field. In this paper, we report observations of possible HFA-like events at Mercury identified over a course of two planetary years. Using data from the orbital phase of the MESSENGER mission, we identify a representative ensemble of active current sheets magnetically connected to Mercury's bow shock. We show that some of these events exhibit magnetic and particle signatures of HFAs similar to those observed at other planets, and present their key physical characteristics. Our analysis suggests that Mercury's bow shock does not only mediate the flow of supersonic solar wind plasma but also provides conditions for local particle acceleration and heating as predicted by previous numerical simulations. Together with earlier observations of HFA activity at Earth, Venus, Mars, and Saturn, our results confirm that hot flow anomalies could be a common property of planetary bow shocks and show that the characteristic size of these events is controlled by the bow shock standoff distance and/or local solar wind conditions.

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Stationarity of magnetohydrodynamic fluctuations in the solar wind

Abstract: Solar wind research and studies of charged particle propagation often assume that the interplanetary magnetic field represents a stationary random process.In this paper we investigate the ,extent to %bich ensemble averages of the

Cited by 139 publications

References 17 publications

Discrete modes and turbulence in a wave‐driven strongly magnetized plasma

Discrete modes and turbulence in a wave‐driven strongly magnetized plasma

Study of the magnetic turbulence in a corotating interaction region in the interplanetary medium

Active current sheets and candidate hot flow anomalies upstream of Mercury's bow shock

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