Observations of Alfvén and Slow Waves in the Solar Wind Near 1 Au

Shi, Mijie; Xiao, Chijie; Li, Q. S.; Wang, H. G.; Wang, X. G.; Li, H.

doi:10.1088/0004-637x/815/2/122

Cited by 27 publications

(23 citation statements)

References 46 publications

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“…The compressive perturbations and non-compressive perturbations are along different slices. He et al 2015;Shi et al 2015). As the current model lacks realistic descriptions of kinetic solar wind processes, the slow magnetosonic waves are identified here.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…A complex mixture of compressible and incompressible fluctuations is involved in the solar wind turbulence, with compressible fluctuations usually as a minor but significant component. The compressibility of solar wind fluctuations usually manifests itself as a slow-mode nature (Burlaga 1968;Tu & Marsch 1994;Hnat et al 2005;Kellogg & Horbury 2005;Yao et al 2011Yao et al , 2013aYao et al , 2013bHowes et al 2012;Klein et al 2012;Zhao et al 2014;He et al 2015;Narita & Marsch 2015;Shi et al 2015Shi et al , 2017Wang et al 2016;Verscharen et al 2017). As the quasi-parallel slow-mode magnetosonic waves are believed to be strongly damped, e.g., can be damped to be less than 1/e of original amplitude within three wavelengths of propagation in the solar corona (Ruan et al 2016), the slow-mode-like compressible fluctuations have often been interpreted as pressure-balanced structures (PBSs; Tu & Marsch 1995).…”

Section: Introductionmentioning

confidence: 99%

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Coexistence of Slow-mode and Alfvén-mode Waves and Structures in 3D Compressive MHD Turbulence

Yang

Zhang

et al. 2018

ApJ

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The compressible component of solar wind turbulence displays a slow-mode feature. However, the nature of the slow-mode fluctuations remain open. In this work, based on numerical simulations of the driven compressible magnetohydrodynamic (MHD) turbulence with a uniform mean magnetic field, we use polarization of the MHD modes to decompose turbulent velocity and magnetic fields into Alfvén modes, slow modes, and fast modes. The numerical results with different cross-helicity, plasma beta β, and Alfvén Mach number note that fast modes are a marginal component among the three decomposed modes, and the compressible component of the MHD turbulence behaves mainly as the slow modes. Both of the decomposed slow modes and Alfvén modes exhibit a Kolmogorov-like power-law spectrum and evident anisotropy, with wavevectors mainly distributing around the directions perpendicular to the uniform mean field. For the first time, it is found that the propagating slow magnetosonic waves as well as the non-propagating slow-mode structures are combined to contribute to the compressible fluctuations, and the propagating Alfvén waves as well as the non-propagating Alfvén-mode structures coexist for the non-compressible fluctuations. However, there is unlikely a one-to-one match between the identified slow waves and Alfvén waves, or between the identified slow-mode structures and Alfvén-mode structures. These findings provide a new perspective on our understanding of the compressible and noncompressible fluctuations.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Coexistence of Slow-mode and Alfvén-mode Waves and Structures in 3D Compressive MHD Turbulence

Yang

Zhang

et al. 2018

ApJ

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“…Our results show that slow MHD waves are generated during the PDI. We propose that this mechanism can explain some of recent observations of slow waves in the solar wind (e.g., Howes et al 2012;Yao et al 2013;He et al 2015;Shi et al 2015).…”

Section: Discussionmentioning

confidence: 68%

“…Yao et al (2013) found that some of the pressure balanced structures (Burlaga & Ogilvie 1970) in the solar wind are driven by oblique propagating slow waves, because oblique propagating slow waves suffer less from Landau damping (Barnes 1979) and may survive in the solar wind. Shi et al (2015) identified some slow wave cases in the solar wind by dispersion relation comparison. He et al (2015) observed the interaction between Alfvén waves and slow waves, and their effects on ion heating.…”

Section: Introductionmentioning

confidence: 99%

The Parametric Decay Instability of Alfvén Waves in Turbulent Plasmas and the Applications in the Solar Wind

Shi

Xiao

et al. 2017

ApJ

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We perform three dimensional (3D) ideal magnetohydrodynamic (MHD) simulations to study the parametric decay instability of Alfvén waves in turbulent plasmas and explore its possible applications in the solar wind. We find that, over a broad range of parameters in background turbulence amplitudes, the parametric decay instability of an Alfvén wave with various amplitudes can still occur, though its growth rate in turbulent plasmas tends to be lower than both the theoretical linear theory prediction and that in the non-turbulent situations. Spatial -temporal FFT analyses of density fluctuations produced by the parametric decay instability match well with the dispersion relation of the slow MHD waves. This result may provide an explanation of the generation mechanism of slow waves in the solar wind observed at 1 AU. It further highlights the need to explore the effects of density variations in modifying the turbulence properties as well as in heating the solar wind plasmas.

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“…Альвеновские волны выделялись по трем критериям: (1) абсолютное значение коэффициента корреляции флуктуаций магнитного поля и скорости превышает 0.9; (2) среднеквадратичное значение флуктуаций модуля магнитного поля составляет не более 0.05 от средней величины B; (3) указан-ные выше условия выполняются для интервала времени длиной 30 мин или более. Обработка данных показала, что доля времени, когда в околоземном СВ наблюдаются альвеновские волны, возрастает с ростом солнечной активности (что согласуется с результатами [7]), причем в быстром СВ альвеновские волны наблюдаются вдвое чаще, чем в медленном.…”

Section: Doi: 1031725/0552-5829-2018-157-160unclassified

Characteristics of Arc-Polarized Alfven Waves in Near-Earth Solar Wind

Erofeev¹

2018

Proceedings of the 22nd All-Russia Conference on Solar and Solar-Terrestrial Physics

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Observations of Alfvén and Slow Waves in the Solar Wind Near 1 Au

Cited by 27 publications

References 46 publications

Coexistence of Slow-mode and Alfvén-mode Waves and Structures in 3D Compressive MHD Turbulence

Coexistence of Slow-mode and Alfvén-mode Waves and Structures in 3D Compressive MHD Turbulence

The Parametric Decay Instability of Alfvén Waves in Turbulent Plasmas and the Applications in the Solar Wind

Characteristics of Arc-Polarized Alfven Waves in Near-Earth Solar Wind

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