Turbulence and Waves in the Solar Wind

Roberts, D. A.; Goldstein, M. L.

doi:10.1002/rog.1991.29.s2.932

Cited by 56 publications

(24 citation statements)

References 197 publications

(211 reference statements)

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“…This is consistent with the scaling predicted by the GS95 model [ Boldyrev , 2005]. Furthermore, observational evidence indicates that inertial range solar wind fluctuations are anisotropic [e.g., Matthaeus et al , 1990; Bieber et al , 1996; Leamon et al , 1998; Dasso et al , 2005; Osman and Horbury , 2007; Hamilton et al , 2008] and that the one‐dimensional magnetic field spectrum exhibits Kolmogorov scaling [e.g., Roberts and Goldstein , 1991; Goldstein et al , 1995; Horbury et al , 2005]. This two‐component model was fitted to the example data interval discussed in section 4 using slab spectral indexes of both 5/3 and 2.…”

Section: Turbulent Field Modelsupporting

confidence: 83%

Quantitative estimates of the slab and 2‐D power in solar wind turbulence using multispacecraft data

Osman

Horbury

2009

J. Geophys. Res.

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[1] A quantitative estimate of the field-aligned anisotropy of magnetohydrodynamic inertial range turbulence is obtained by comparing multispacecraft data with a fully threedimensional turbulent magnetic field numerical model. The simulated turbulence is a superposition of slab fluctuations parallel to the mean field and 2-D fluctuations perpendicular to it. This model is fitted to spatial autocorrelation functions, computed from measurements made by the four Cluster spacecraft in the solar wind, by varying the slab-2-D fraction. The mean power in the 2-D fluctuations, 81 ± 3%, is consistent with solar wind fluctuations being anisotropic with energy mainly in wave vectors perpendicular to the large-scale mean magnetic field. Eight intervals of multipoint magnetic field data are analyzed, and a large degree of variation in the anisotropy estimates about the mean is observed. The origin of this variability is unclear. However, variations in the anisotropy estimates are correlated between different field components.Citation: Osman, K. T., and T. S. Horsbury (2009), Quantitative estimates of the slab and 2-D power in solar wind turbulence using multispacecraft data,

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Section: Turbulent Field Modelsupporting

confidence: 83%

Quantitative estimates of the slab and 2‐D power in solar wind turbulence using multispacecraft data

Osman

Horbury

2009

J. Geophys. Res.

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“…Since observations and simulations of RDs with small to moderate 8• suggest significant in situ evolution, it is possible that a significant number of RDs are formed locally in the solar wind. Such in situ evolution in the solar wind has been identified for the Alfv6nic fluctuations [e.g., Roberts and Goldstein, 1991], and so perhaps RDs evolve in a way intimately related to this dominant component beyond the corona.…”

Section: Because Nonlinearity Has a Weaker Influence On Fight Helicitymentioning

confidence: 81%

“…Burlaga [ 1971 ] showed that RDs in the solar wind do not cluster in stream interaction regions, and so the majority of RDs do not originate there. Instead, because most RDs propagate outwards are irregular in structure, propagate and evolve in a turbulent and nonuniform medium, where their structures are modified by spherical expansion, shear and compression as they are convected away from the Sun [Roberts and Goldstein, 1991]. Presumably, all this also occurs to RDs, but these factors have not been taken account in explaining RD formation, and the answer may lie among them.…”

Section: Evolution Of Rds With Other Values Of L and • _mentioning

confidence: 99%

A wave model interpretation of the evolution of rotational discontinuities

Vasquez¹,

Cargill²

1993

J. Geophys. Res.

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The evolution of rotational discontinuities (RDs) is followed using a hybrid numerical code. An extensive parameter variation is carried out, with particular emphasis on β, Ti/Te, θB (the angle between the normal and total magnetic field), and the helicity of the RD. The RD structure is shown to have features in common with the evolution of both strongly modulated, nonlinear wave packets and linear dispersive wave propagation in oblique magnetic fields. For small θB, the RD disperses linearly giving fast and Alfvén waves upstream and downstream, respectively, and the familiar S‐shaped hodograms. At larger θB (≈ 30°), nonlinearity becomes important and strong coupling to a compressional (sonic) component can occur in the main current layer. When the ions are cold, there is a critical value of βe(=β*) when the intermediate wave train moves from the downstream side of the RD to the upstream and is replaced on the downstream side by slow modes. This is reflected in the hodograms by a change of the wave polarization on both sides, and represents an important modification to the original Goodrich and Cargill (1991) wave model of RDs. As Ti/Te increases, the spreading rate of the current layer increases for moderate θB. For large θB(≈ 60°), RDs with electron (ion) sense of rotation show increased (decreased) spreading with increasing Ti/Te. These results are applied to RDs observed in the solar wind and at the magnetopause.

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“…The slow solar wind, on the other hand is highly variable in its flow parameters and therefore dynamically active from the time it leaves the corona. Its turbulence parameters show that it is highly evolved by 1 AU [ Bavassano et al , 1982b; Denskat and Neubauer , 1982] and that it evolves at a decreasing rate beyond 1 AU [ Roberts et al , 1987; Roberts and Goldstein , 1991].…”

Section: Introductionmentioning

confidence: 99%

Turbulence and intermittency in the heliospheric magnetic field in fast and slow solar wind

et al. 2009

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We study the nonuniform solar wind turbulence using high‐resolution Ulysses magnetic field data measured at different solar activity level, heliospheric latitudes, and distance. We define several types of solar wind dependent of the coronal region of origin and also of the dynamical behavior of the different streams, namely, “pure” fast wind, fast streams, “pure” slow wind, and slow streams. The turbulent properties of the solar wind types were investigated in terms of their scaling properties and spatial inhomogeneity. A clear trend in the power spectrum of the solar wind magnetic field magnitude is observed: the “pure” fast wind has a slope ∼−1.33 (1/f‐like), the fast streams ∼−1.48 (Kraichnan‐like), the “pure” slow wind ∼−1.67 (Kolmogorov‐like), and the slow streams ∼−1.72. We find that the “pure” fast wind in the polar heliolatitudes is less intermittent than the other types: “pure” slow wind and both slow and fast streams, which is because of the absence of dynamical interactions between streams with different speeds. On the other hand, fast streams are more intermittent than the “pure” fast wind, and slow streams are less intermittent than the “pure” slow winds. A clear radial and latitudinal evolution of the intermittency is observed only for the “pure” fast wind, while in the equatorial plane, the fast streams, the “pure” slow wind, and the slow streams do not show evolution either in heliolatitude or in heliocentric distance.

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Turbulence and Waves in the Solar Wind

Cited by 56 publications

References 197 publications

Quantitative estimates of the slab and 2‐D power in solar wind turbulence using multispacecraft data

Quantitative estimates of the slab and 2‐D power in solar wind turbulence using multispacecraft data

A wave model interpretation of the evolution of rotational discontinuities

Turbulence and intermittency in the heliospheric magnetic field in fast and slow solar wind

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