scholarly journals The Evolution and Role of Solar Wind Turbulence in the Inner Heliosphere

2020 ◽  
Author(s):  
Christopher Chen ◽  
Keyword(s):  
Solar Wind ◽  
Kinetic Energy ◽  
Large Scale ◽  
Energy Levels ◽  
Turbulence Energy ◽  
Energy Fraction ◽  
Solar Wind Turbulence ◽  
Rate Of Increase ◽  
Wind Turbulence ◽  
Order Of Magnitude

<p>The first two orbits of the Parker Solar Probe (PSP) spacecraft have enabled the first in situ measurements of the solar wind down to a heliocentric distance of 0.17 au (or 36 Rs). Here, we present an analysis of this data to study solar wind turbulence at 0.17 au and its evolution out to 1 au. While many features remain similar, key differences at 0.17 au include: increased turbulence energy levels by more than an order of magnitude, a magnetic field spectral index of -3/2 matching that of the velocity and both Elsasser fields, a lower magnetic compressibility consistent with a smaller slow-mode kinetic energy fraction, and a much smaller outer scale that has had time for substantial nonlinear processing. There is also an overall increase in the dominance of outward-propagating Alfvenic fluctuations compared to inward-propagating ones, and the radial variation of the inward component is consistent with its generation by reflection from the large-scale gradient in Alfven speed. The energy flux in this turbulence at 0.17 au was found to be ~10% of that in the bulk solar wind kinetic energy, becoming ~40% when extrapolated to the Alfven point, and both the fraction and rate of increase of this flux towards the Sun is consistent with turbulence-driven models in which the solar wind is powered by this flux.</p>

scholarly journals Solar cycle changes in the geo-effectiveness of small-scale solar wind turbulence measured by Wind and ACE at 1 AU

2007 ◽  
Vol 25 (5) ◽  
pp. 1183-1197 ◽  
Author(s):  
M. L. Parkinson ◽  
R. C. Healey ◽  
P. L. Dyson
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Solar Minimum ◽  
Large Scale ◽  
Small Scale ◽  
Scaling Exponent ◽  
Mhd Turbulence ◽  
Scaling Exponents ◽  
Solar Wind Turbulence ◽  
Wind Turbulence

Abstract. Multi-scale structure of the solar wind in the ecliptic at 1 AU undergoes significant evolution with the phase of the solar cycle. Wind spacecraft measurements during 1995 to 1998 and ACE spacecraft measurements during 1997 to 2005 were used to characterise the evolution of small-scale (~1 min to 2 h) fluctuations in the solar wind speed vsw, magnetic energy density B2, and solar wind ε parameter, in the context of large-scale (~1 day to years) variations. The large-scale variation in ε most resembled large-scale variations in B2. The probability density of large fluctuations in ε and B2 both had strong minima during 1995, a familiar signature of solar minimum. Generalized Structure Function (GSF) analysis was used to estimate inertial range scaling exponents aGSF and their evolution throughout 1995 to 2005. For the entire data set, the weighted average scaling exponent for small-scale fluctuations in vsw was aGSF=0.284±0.001, a value characteristic of intermittent MHD turbulence (>1/4), whereas the scaling exponents for corresponding fluctuations in B2 and ε were aGSF=0.395±0.001 and 0.334±0.001, respectively. These values are between the range expected for Gaussian fluctuations (1/2) and Kolmogorov turbulence (1/3). However, the scaling exponent for ε changed from a Gaussian-Kolmogorov value of 0.373±0.005 during 1997 (end of solar minimum) to an MHD turbulence value of 0.247±0.004 during 2003 (recurrent fast streams). Changes in the characteristics of solar wind turbulence may be reproducible from one solar cycle to the next.

scholarly journals The Near-Sun Streamer Belt Solar Wind: Turbulence and Solar Wind Acceleration

2021 ◽  
Author(s):  
Christopher Chen ◽  
Benjamin Chandran ◽  
Lloyd Woodham ◽  
Shaela Jones ◽  
Jean Perez ◽  
...  
Keyword(s):  
Solar Wind ◽  
Turbulence Models ◽  
Heliospheric Current Sheet ◽  
Angular Distance ◽  
Slow Solar Wind ◽  
Turbulence Energy ◽  
Streamer Belt ◽  
Solar Wind Acceleration ◽  
Solar Wind Turbulence ◽  
Wind Turbulence

<p>The fourth orbit of Parker Solar Probe (PSP) reached heliocentric distances down to 27.9 Rs, allowing solar wind turbulence and acceleration mechanisms to be studied in situ closer to the Sun than previously possible. The turbulence properties were found to be significantly different in the inbound and outbound portions of PSP's fourth solar encounter, likely due to the proximity to the heliospheric current sheet (HCS) in the outbound period. Near the HCS, in the streamer belt wind, the turbulence was found to have lower amplitudes, higher magnetic compressibility, a steeper magnetic field spectrum (with spectral index close to -5/3 rather than -3/2), a lower Alfvenicity, and a "1/f" break at much lower frequencies. These are also features of slow wind at 1 au, suggesting the near-Sun streamer belt wind to be the prototypical slow solar wind. The transition in properties occurs at a predicted angular distance of ~4 degrees from the HCS, suggesting ~8 degrees as the full-width of the streamer belt wind at these distances. While the majority of the Alfvenic turbulence energy fluxes measured by PSP are consistent with those required for reflection-driven turbulence models of solar wind acceleration, the fluxes in the streamer belt are significantly lower than the model predictions, suggesting that additional mechanisms are necessary to explain the acceleration of the streamer belt solar wind.</p>

scholarly journals The Relationship Between Solar Wind Dynamic Pressure Pulses and Solar Wind Turbulence

2021 ◽  
Vol 9 ◽  
Author(s):  
Mengsi Ruan ◽  
Pingbing Zuo ◽  
Zilu Zhou ◽  
Zhenning Shen ◽  
Yi Wang ◽  
...  
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Dynamic Pressure ◽  
Solar Wind Dynamic Pressure ◽  
Occurrence Rate ◽  
Time Lags ◽  
Gaussian Distributions ◽  
Solar Wind Turbulence ◽  
Wind Turbulence ◽  
Pressure Pulses

Solar wind dynamic pressure pulses (DPPs) are small-scale plasma structures with abrupt and large-amplitude plasma dynamic pressure changes on timescales of seconds to several minutes. Overwhelming majority of DPP events (around 79.13%) reside in large-scale solar wind transients, i.e., coronal mass ejections, stream interaction regions, and complex ejecta. In this study, the intermittency, which is a typical feature of solar wind turbulence, is determined and compared during the time intervals in the undisturbed solar wind and in large-scale solar wind transients with clustered DPP events, respectively, as well as in the undisturbed solar wind without DPPs. The probability distribution functions (PDFs) of the fluctuations of proton density increments normalized to the standard deviation at different time lags in the three types of distinct regions are calculated. The PDFs in the undisturbed solar wind without DPPs are near-Gaussian distributions. However, the PDFs in the solar wind with clustered DPPs are obviously non-Gaussian distributions, and the intermittency is much stronger in the large-scale solar wind transients than that in the undisturbed solar wind. The major components of the DPPs are tangential discontinuities (TDs) and rotational discontinuities (RDs), which are suggested to be formed by compressive magnetohydrodynamic (MHD) turbulence. There are far more TD-type DPPs than RD-type DPPs both in the undisturbed solar wind and large-scale solar wind transients. The results imply that the formation of solar wind DPPs could be associated with solar wind turbulence, and much stronger intermittency may be responsible for the high occurrence rate of DPPs in the large-scale solar wind transients.

Large-scale structure of solar wind turbulence near solar activity minimum

2000 ◽  
Vol 25 (9) ◽  
pp. 1943-1946 ◽  
Author(s):  
M. Tokumaru ◽  
M. Kojima ◽  
Y. Ishida ◽  
A. Yokobe ◽  
T. Ohmi
Keyword(s):  
Solar Wind ◽  
Solar Activity ◽  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Solar Activity Minimum ◽  
Solar Wind Turbulence ◽  
Wind Turbulence

scholarly journals Evolution of turbulent kinetic energy during the entire sandstorm process

2021 ◽  
Author(s):  
Hongyou Liu ◽  
Yanxiong Shi ◽  
Xiaojing Zheng
Keyword(s):  
Energy Transfer ◽  
Kinetic Energy ◽  
Turbulent Kinetic Energy ◽  
Large Scale ◽  
Wall Turbulence ◽  
Turbulence Energy ◽  
Two Phase ◽  
Energy Fraction ◽  
Quadratic Phase ◽  
Non Stationary Signal

Abstract. An adaptive segmented stationary method for non-stationary signal is proposed to reveal the turbulent kinetic energy evolution during the entire sandstorm process observed at the Qingtu Lake Observation Array. Sandstorm which is a common natural disaster is mechanically characterized by a particle-laden two-phase flow experiencing wall turbulence, with an extremely high Reynolds number and significant turbulent kinetic energy. Turbulence energy transfer is important to the understanding of sandstorm dynamics. This study indicates that large-/very-large-scale coherent structures originally exist in the rising stage of sandstorms with a streamwise kinetic energy of 75 % rather than gradually forming. In addition to carrying a substantial portion of energy, the very-large-scale-motions are active structures with strong nonlinear energy transfer. These structures gain energy from strong nonlinear interaction. As sandstorm evolves, these large structures are gradually broken by quadratic phase coupling, with the energy fraction reducing to 40 % in the declining stage. The nonlinear process in the steady and declining stages weakens and maintains a balanced budget of energy. The systematic bispectrum results provide a new perspective for further insight of sandstorms.

Observational Test for a Random Sweeping Model in Solar Wind Turbulence

2016 ◽  
Vol 116 (12) ◽  
Author(s):  
C. Perschke ◽  
Y. Narita ◽  
U. Motschmann ◽  
K. H. Glassmeier
Keyword(s):  
Solar Wind ◽  
Observational Test ◽  
Solar Wind Turbulence ◽  
Wind Turbulence

Large-scale Structure and Turbulence Transport in the Young Solar Wind – Comparison of Parker Solar Probe Observations with a Global 3D Reynolds-averaged MHD Model

2021 ◽  
Author(s):  
Rohit Chhiber ◽  
Arcadi Usmanov ◽  
William Matthaeus ◽  
Melvyn Goldstein ◽  
Riddhi Bandyopadhyay
Keyword(s):  
Solar Wind ◽  
Large Scale ◽  
Transport Equations ◽  
Turbulence Energy ◽  
Reynolds Stresses ◽  
Mean Flow ◽  
Coulomb Collisions ◽  
Flow Equations ◽  
Simulation Results ◽  
Turbulence Transport

<div>Simulation results from a global <span>magnetohydrodynamic</span> model of the solar corona and the solar wind are compared with Parker Solar <span>Probe's</span> (<span>PSP</span>) observations during its first several orbits. The fully three-dimensional model (<span>Usmanov</span> <span>et</span> <span>al</span>., 2018, <span>ApJ</span>, 865, 25) is based on Reynolds-averaged mean-flow equations coupled with turbulence transport equations. The model accounts for effects of electron heat conduction, Coulomb collisions, Reynolds stresses, and heating of protons and electrons via nonlinear turbulent cascade. Turbulence transport equations for turbulence energy, cross <span>helicity</span>, and correlation length are solved concurrently with the mean-flow equations. We specify boundary conditions at the coronal base using solar synoptic <span>magnetograms</span> and calculate plasma, magnetic field, and turbulence parameters along the <span>PSP</span> trajectory. We also accumulate data from all orbits considered, to obtain the trends observed as a function of heliocentric distance. Comparison of simulation results with <span>PSP</span> data show general agreement. Finally, we generate synthetic fluctuations constrained by the local rms turbulence amplitude given by the model, and compare properties of this synthetic turbulence with PSP observations.</div>

Erratum: “3D Anisotropy of Solar Wind Turbulence, Tubes, or Ribbons?” (2018, ApJ, 853, 85)

2018 ◽  
Vol 867 (2) ◽  
pp. 168 ◽  
Author(s):  
Andrea Verdini ◽  
Roland Grappin ◽  
Olga Alexandrova ◽  
Sonny Lion
Keyword(s):  
Solar Wind ◽  
Solar Wind Turbulence ◽  
Wind Turbulence

scholarly journals Kinetic Cascade in Solar-wind Turbulence: 3D3V Hybrid-kinetic Simulations with Electron Inertia

2017 ◽  
Vol 846 (2) ◽  
pp. L18 ◽  
Author(s):  
Silvio Sergio Cerri ◽  
Sergio Servidio ◽  
Francesco Califano
Keyword(s):  
Solar Wind ◽  
Electron Inertia ◽  
Solar Wind Turbulence ◽  
Wind Turbulence
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