Solar-Wind Structures That Are Not Destroyed by the Action of Solar-Wind Turbulence

Frontiers in Astronomy and Space Sciences ◽

10.3389/fspas.2021.721350 ◽

2021 ◽

Vol 8 ◽

Author(s):

Joseph E. Borovsky

Keyword(s):

Solar Wind ◽

Magnetic Structure ◽

Solar Wind Plasma ◽

Ion Composition ◽

Mhd Turbulence ◽

Current Sheets ◽

Wind Structure ◽

Solar Wind Structure ◽

Wind Measurements ◽

Dominant Process

If MHD turbulence is a dominant process acting in the solar wind between the Sun and 1 AU, then the destruction and regeneration of structure in the solar-wind plasma is expected. Six types of solar-wind structure at 1 AU that are not destroyed by turbulence are examined: 1) corotating-interaction-region stream interfaces, 2) periodic density structures, 3) magnetic structure anisotropy, 4) ion-composition boundaries and their co-located current sheets, 5) strahl-intensity boundaries and their co-located current sheets, and 6) non-evolving Alfvénic magnetic structure. Implications for the solar wind and for turbulence in the solar wind are highlighted and a call for critical future solar-wind measurements is given.

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Current sheets from Ulysses observation

Annales Geophysicae ◽

10.5194/angeo-29-237-2011 ◽

2011 ◽

Vol 29 (2) ◽

pp. 237-249 ◽

Cited By ~ 33

Author(s):

B. Miao ◽

B. Peng ◽

G. Li

Keyword(s):

Solar Wind ◽

Current Sheet ◽

Solar Wind Plasma ◽

Mhd Turbulence ◽

Automatic Data ◽

Flux Tubes ◽

Current Sheets ◽

Solar Origin ◽

Turbulence Intermittency ◽

Solar Wind Magnetic Field

Abstract. Current sheet is a significant source of solar wind MHD turbulence intermittency. It has long been recognized that these structures can arise from non-linear interactions of MHD turbulence. Alternatively, they may also be relic structures in the solar wind that have a solar origin, e.g., magnetic walls of flux tubes that separate solar wind plasma into distinct parcels. Identifying these structures in the solar wind is crucial to understanding the properties of the solar wind MHD turbulence. Using Ulysses observations we examine 3-year worth of solar wind magnetic field data when the Ulysses is at low latitude during solar minimum. Extending the previous work of Li (2007, 2008), we develop an automatic data analysis method of current sheet identification. Using this method, we identify more than 28000 current sheets. Various properties of the current sheet are obtained. These include the distributions of the deflection angle across the current sheet, the thickness of the current sheet and the waiting time statistics between current sheets.

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Empirical inner boundary conditions and rotation rates for solar wind models

10.5194/egusphere-egu21-782 ◽

2021 ◽

Author(s):

Huw Morgan

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Boundary Conditions ◽

Coronal Magnetic Field ◽

Height Range ◽

Rotation Rates ◽

Wind Structure ◽

Solar Wind Structure ◽

Coronal Electron ◽

Made In

<p>To date, the inner boundary conditions for solar wind models are either directly or indirectly based on magnetic field extrapolation models of the photosphere. Furthermore, between the photosphere and Earth, there are no other direct empirical constraints on models. New breakthroughs in coronal rotation tomography, applied to coronagraph observations, allow maps of the coronal electron density to be made in the heliocentric height range 4-12 solar radii (Rs). We show that these maps (i) give a new empirical boundary condition for solar wind structure at a height where the coronal magnetic field has become radial, thus avoiding the need to model the complex inner coronal magnetic field, and (ii) give accurate rotation rates for the corona, of crucial importance to the accuracy of solar wind models and forecasts.</p>

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Solar cycle changes of large-scale solar wind structure

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309992912 ◽

2009 ◽

Vol 5 (S264) ◽

pp. 356-358 ◽

Cited By ~ 3

Author(s):

P. K. Manoharan

Keyword(s):

Solar Wind ◽

Solar Cycle ◽

Large Scale ◽

Interplanetary Space ◽

The Sun ◽

Wind Structure ◽

Level Of Activity ◽

Solar Wind Structure ◽

Current Minimum ◽

Inner Heliosphere

AbstractIn this paper, I present the results on large-scale evolution of density turbulence of solar wind in the inner heliosphere during 1985–2009. At a given distance from the Sun, the density turbulence is maximum around the maximum phase of the solar cycle and it reduces to ~70%, near the minimum phase. However, in the current minimum of solar activity, the level of turbulence has gradually decreased, starting from the year 2005, to the present level of ~30%. These results suggest that the source of solar wind changes globally, with the important implication that the supply of mass and energy from the Sun to the interplanetary space has significantly reduced in the present low level of activity.

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Evolution of the MHD turbulence properties in the inner heliosphere with the PSP/SolO alignment data

10.5194/egusphere-egu21-14585 ◽

2021 ◽

Author(s):

Daniele Telloni ◽

Keyword(s):

Solar Wind ◽

High Frequency ◽

Interplanetary Space ◽

Solar Wind Plasma ◽

Radial Dependence ◽

Physical Processes ◽

Temperature Anisotropy ◽

Mhd Turbulence ◽

Radial Evolution ◽

Inner Heliosphere

<p>Radial alignments between pairs of spacecraft is the only way to observationally investigate the turbulent evolution of the solar wind as it expands throughout interplanetary space. On September 2020 Parker Solar Probe (PSP) and Solar Orbiter (SolO) were nearly perfectly radially aligned, with PSP orbiting around its perihelion at 0.1 au (and crossing the nominal Alfv&#233;n point) and SolO at 1 au. PSP/SolO joint observations of the same solar wind plasma allow the extraordinary and unprecedented opportunity to study how the turbulence properties of the solar wind evolve in the inner heliosphere over the wide distance of 0.9 au. The radial evolution of (i) the MHD properties (such as radial dependence of low- and high-frequency breaks, compressibility, Alfv&#233;nic content of the fluctuations), (ii) the polarization status, (iii) the presence of wave modes at kinetic scale as well as their distribution in the plasma instability-temperature anisotropy plane are just few instances of what can be addressed. Of furthest interest is the study of whether and how the cascade transfer and dissipation rates evolve with the solar distance, since this has great impact on the fundamental plasma physical processes related to the heating of the solar wind. In this talk I will present some of the results obtained by exploiting the PSP/SolO alignment data.</p>

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