The turbulent density spectrum in the solar wind plasma

Shaikh, Dastgeer; Zank, G. P.

doi:10.1111/j.1365-2966.2009.15881.x

Cited by 21 publications

(16 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This result is comparable with in situ solar wind observations (Tu & Marsch 1994;Yao et al 2011) and previous simulation (Shaikh & Zank 2010). Also, in the inertial range, the spectra of P mag and P th are close, which indicates their amplitude change similarly over the various spatial scales.…”

Section: Numerical Resultssupporting

confidence: 80%

Multiscale Pressure-Balanced Structures in Three-dimensional Magnetohydrodynamic Turbulence

Yang

et al. 2017

ApJ

View full text Add to dashboard Cite

Observations of solar wind turbulence indicate the existence of multi-scale pressurebalanced structures (PBSs) in the solar wind. In this work, we conduct a numerical simulation to investigate multi-scale PBSs and in particular their formation in compressive MHD turbulence. By the use of a higher order Godunov code Athena, a driven compressible turbulence with an imposed uniform guide field is simulated. The simulation results show that both the magnetic pressure and the thermal pressure exhibit a turbulent spectrum with a Kolmogorov-like power law, and that in many regions of the simulation domain they are anti-correlated. The computed wavelet cross-coherence spectrum of the magnetic pressure and the thermal pressure, as well as their space series, indicate the existence of multi-scale PBSs, with the small PBSs being embedded in the large ones. These multi-scale PBSs are likely to be related with the highly obliquepropagating slow-mode waves, as the traced multi-scale PBS is found to be traveling in a certain direction at a speed consistent with that predicted theoretically for a slow-mode wave propagating in the same direction.

show abstract

Section: Numerical Resultssupporting

confidence: 80%

Multiscale Pressure-Balanced Structures in Three-dimensional Magnetohydrodynamic Turbulence

Yang

et al. 2017

ApJ

View full text Add to dashboard Cite

show abstract

“…According to the Morokovin hypothesis, which has been verified extensively via numerical simulations (e.g., Duan, Beekman & Martin 2011) a subsonic turbulent drag law is valid even for supersonic flows as long as the fluctuations in the turbulent boundary layer are incompressible, or subsonic. The turbulent fluctuations in the ambient solar wind are certainly incompressible to a very good approximation (e.g., Shaikh & Zank 2010). This is also evident from the small values of the density fluctuation ∆n/n in the ambient solar wind (e.g., Bisoi et al 2014).…”

Section: Drag Modelmentioning

confidence: 92%

Cme Propagation: Where Does Aerodynamic Drag “Take Over”?

Sachdeva

Subramanian

Colaninno

et al. 2015

ApJ

View full text Add to dashboard Cite

We investigate the Sun-Earth dynamics of a set of eight well observed solar coronal mass ejections (CMEs) using data from the STEREO spacecraft. We seek to quantify the extent to which momentum coupling between these CMEs and the ambient solar wind (i.e., the aerodynamic drag) influences their dynamics. To this end, we use results from a 3D flux rope model fit to the CME data.We find that solar wind aerodynamic drag adequately accounts for the dynamics of the fastest CME in our sample. For the relatively slower CMEs, we find that drag-based models initiated below heliocentric distances ranging from 15 to 50 R ⊙ cannot account for the observed CME trajectories. This is at variance with the general perception that the dynamics of slow CMEs are influenced primarily by solar wind drag from a few R ⊙ onwards. Several slow CMEs propagate at roughly constant speeds above 15-50 R ⊙ . Drag-based models initiated above these heights therefore require negligible aerodynamic drag to explain their observed trajectories.

show abstract

“…This leads us to the conclusion that observations of Type III solar radio burst sizes and durations, over a broad range of frequencies, require anisotropic scattering, in the entire heliosphere between the Sun and the Earth, with an anisotropy factor of around 3-4 and with the density fluctuations predominantly perpendicular to the radial direction. As discussed in Section 6, these observations provide essential density fluctuation anisotropy constraints for MHD turbulence models (Shaikh & Zank 2010;Zank et al 2012) over a wide range of locations between the Sun and the Earth.…”

Section: Introductionmentioning

confidence: 96%

Anisotropic Radio-wave Scattering and the Interpretation of Solar Radio Emission Observations

Kontar

Chen

Chrysaphi

et al. 2019

ApJ

147

View full text Add to dashboard Cite

The observed properties (i.e., source size, source position, time duration, decay time) of solar radio emission produced through plasma processes near the local plasma frequency, and hence the interpretation of solar radio bursts, are strongly influenced by propagation effects in the inhomogeneous turbulent solar corona. In this work, a 3D stochastic description of the propagation process is presented, based on the Fokker-Planck and Langevin equations of radio-wave transport in a medium containing anisotropic electron density fluctuations. Using a numerical treatment based on this model, we investigate the characteristic source sizes and burst decay times for Type III solar radio bursts. Comparison of the simulations with the observations of solar radio bursts shows that predominantly perpendicular density fluctuations in the solar corona are required, with an anisotropy factor ∼ 0.3 for sources observed at around 30 MHz. The simulations also demonstrate that the photons are isotropized near the region of primary emission, but the waves are then focused by large-scale refraction, leading to plasma radio emission directivity that is characterized by a half-width-half-maximum of about 40 degrees near 30 MHz. The results are applicable to various solar radio bursts produced via plasma emission.

show abstract

The turbulent density spectrum in the solar wind plasma

Cited by 21 publications

References 68 publications

Multiscale Pressure-Balanced Structures in Three-dimensional Magnetohydrodynamic Turbulence

Multiscale Pressure-Balanced Structures in Three-dimensional Magnetohydrodynamic Turbulence

Cme Propagation: Where Does Aerodynamic Drag “Take Over”?

Anisotropic Radio-wave Scattering and the Interpretation of Solar Radio Emission Observations

Contact Info

Product

Resources

About