(Non)-radial propagation of the solar wind flow

2020 ◽  
Author(s):  
Zdeněk Němeček ◽  
Tereza Ďurovcová ◽  
Jana Šafránková ◽  
Jiří Šimůnek ◽  
John D. Richardson ◽  
...  
Keyword(s):  
Solar Wind ◽  
Radial Velocity ◽  
Orbital Motion ◽  
Wind Flow ◽  
The Sun ◽  
Mars Express ◽  
The Earth ◽  
Solar Wind Flow ◽  
Magnetospheric Tail ◽  
Radial Propagation

<p>The solar wind aberration due to non-radial velocity components and the Earth orbital motion is important for the overall magnetosphere geometry because the magnetospheric tail is aligned with the solar wind flow. This paper investigates an evolution of non-radial components of the solar wind flow along the path from the Sun to 6 AU. A comparison of observations at 1 AU and closer to or further from the Sun based on measurements of many spacecraft at different locations in the heliosphere (Wind, ACE, Spektr-R, THEMIS B and C, Helios 1 and 2, Mars-Express, Voyager 1 and 2) shows that (i) the average values of non-radial components vary with the distance from the Sun and (ii) they differ according to solar wind streams.</p>

scholarly journals Occurrence rate of magnetic holes between 0.72 and 1 AU: comparative study of Cluster and VEX data

2011 ◽  
Vol 29 (5) ◽  
pp. 717-722 ◽  
Author(s):  
O. A. Amariutei ◽  
S. N. Walker ◽  
T. L. Zhang
Keyword(s):  
Solar Wind ◽  
Occurrence Rate ◽  
Wind Flow ◽  
The Sun ◽  
Common Features ◽  
The Earth ◽  
Magnetic Field Magnitude ◽  
Solar Wind Flow ◽  
Stable Plasma ◽  
The Magnetic Field

Abstract. Localised depressions in the magnetic field magnitude, or magnetic holes, are common features in many regions of solar system plasma. Two distinct mechanisms for their generation have been proposed. The first proposed that the structures are generated locally, close to the point of observation. The alternative has been proposed by Russell et al. (2008), who suggest that the observed magnetic holes represent nonlinear mirror structures that can be carried by the solar wind over vast distances of mirror stable plasma. According to Russell et al. (2008), magnetic holes are created in the vicinity of the sun and are convected by the solar wind outward. Periods of Cluster 1 and VEX data when both spacecraft were connected by the solar wind flow have been considered in this study, in order to determine the evolution of the magnetic holes occurrence rate. The comparison of the magnetic holes occurrence near the Venus and the Earth supports the Russell et al. (2008) premise that they are generated closer to the Sun most likely somewhere within the orbit of Mercury.

Plasma processes at comet Churyumov–Gerasimenko: Expectations for Rosetta

2013 ◽  
Vol 79 (6) ◽  
pp. 1067-1070 ◽  
Author(s):  
D. A. MENDIS ◽  
M. HORÁNYI
Keyword(s):  
Solar Wind ◽  
Solar Radiation ◽  
Bow Shock ◽  
Short Paper ◽  
Wind Flow ◽  
The Sun ◽  
Cometary Plasma ◽  
Variable Nature ◽  
Solar Wind Flow ◽  
Comet 67P

AbstractThe Rosetta–Philae mission to comet 67P/Churyumov–Gerasimenko in 2014 will provide a unique opportunity to observe the variable nature of the interaction of a comet with the solar radiation and the solar wind, as the comet approaches the Sun. In this short paper we will focus on the varying global structure of the cometary plasma environment. Specifically we make predictions on the varying locations of the two basic transitions in the global, contaminated solar wind flow toward the comet: the outer bow shock and the ionopause.

Modelling the evolution of CMEs and their shocks through different solar wind structures

2020 ◽  
Author(s):  
Erika Palmerio ◽  
Christina Lee ◽  
Leila Mays ◽  
Dusan Odstrcil
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Vantage Point ◽  
Angular Width ◽  
Wind Flow ◽  
The Sun ◽  
Ambient Wind ◽  
Fast Wind ◽  
Solar Wind Flow ◽  
Ambient Solar Wind

<p>The evolution of coronal mass ejections (CMEs) as they travel away from the Sun is one of the major issues in heliophysics and space weather. After erupting, CMEs propagate outwards through the background solar wind flow, which in turn may significantly affect CME evolution by means of e.g. acceleration, deflection, and/or rotation. In order to determine to which extent the ambient wind can alter the speed, trajectory, and orientation of a CME, we run a series of 3D magnetohydrodynamics simulations (using the coupled solar–heliospheric WSA–Enlil model) to conduct a multi-vantage point study of the radial and longitudinal evolution of CME structures as they propagate up to Earth’s (1 AU) and Mars’ (1.5 AU) orbits. We explore a broad range of input CME parameters (initial radial speed, angular width) and ambient solar wind conditions (slow versus fast wind) to investigate the different evolutionary behaviours of CMEs and their driven shocks and sheath regions. To study the radial and longitudinal evolution for the modelled CME ejecta and shock events, we examine the resulting magnetic field and plasma time series at different heliocentric distances (0.5 AU, 1 AU, and 1.5 AU) and heliolongitudes (in 30° increments). This work will help establish a set of expected CME behaviours at Earth’s and Mars’ radial distances, which can be used for analysing real CME events.</p>

Evolution of the Solar Wind Direction through the Heliosphere

2021 ◽  
Author(s):  
Zdeněk Němeček ◽  
Tereza Ďurovcová ◽  
Jana Šafránková ◽  
John D. Richardson ◽  
Jiří Šimůnek ◽  
...  
Keyword(s):  
Solar Wind ◽  
Radial Velocity ◽  
Radial Direction ◽  
Solar Wind Plasma ◽  
Coronal Magnetic Field ◽  
The Sun ◽  
Transient Phenomena ◽  
Solar Wind Flow ◽  
The Difference ◽  
Outer Corona

<p>The solar wind non-radial velocity components observed beyond the Alfvén point are usually attributed to waves, the interaction of different streams, or other transient phenomena. However, Earth-orbiting spacecraft as well as monitors at L1 indicate systematic deviations of the wind velocity from the radial direction. Since these deviations are of the order of several degrees, the calibration of the instruments is often questioned. This paper investigates for the first time the evolution of non-radial components of the solar wind flow along the path from ≈ 0.17 to 10 AU. A comparison of observations at 1 AU with those closer to or farther from the Sun based on measurements of many spacecraft at different locations in the heliosphere (Parker Solar Probe, Helios 1 and 2, Wind, ACE, Spektr-R, ARTEMIS probes, MAVEN, Voyagers 1and 2) shows that (i) the average values of non-radial components are not zero and vary in a systematic manner with the distance from the Sun, (ii) their values significantly depend on the solar wind radial velocity, (iii) the deviation from radial direction well correlates with the cross-helicity, and (iv) the values of non-radial components peaks at 0.25 AU and gradually decreases toward zero in the outer heliosphere. Our results suggest that the difference in the propagation direction between the faster and slower winds is already established in the solar corona and is connected with the forces emitting solar wind plasma from the coronal magnetic field. The correlation with cross-helicity probably points to outward propagating Alfven waves generated in outer corona as the most probable source of observed deviations.</p>

scholarly journals A review of the SCOSTEP’s 5-year scientific program VarSITI—Variability of the Sun and Its Terrestrial Impact

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Kazuo Shiokawa ◽  
Katya Georgieva
Keyword(s):  
Solar Wind ◽  
Interplanetary Space ◽  
Solar Wind Plasma ◽  
The Sun ◽  
Scientific Program ◽  
Solar Cycles ◽  
Grand Minimum ◽  
The Earth ◽  
Earth Connection ◽  
Near Future

AbstractThe Sun is a variable active-dynamo star, emitting radiation in all wavelengths and solar-wind plasma to the interplanetary space. The Earth is immersed in this radiation and solar wind, showing various responses in geospace and atmosphere. This Sun–Earth connection variates in time scales from milli-seconds to millennia and beyond. The solar activity, which has a ~11-year periodicity, is gradually declining in recent three solar cycles, suggesting a possibility of a grand minimum in near future. VarSITI—variability of the Sun and its terrestrial impact—was the 5-year program of the scientific committee on solar-terrestrial physics (SCOSTEP) in 2014–2018, focusing on this variability of the Sun and its consequences on the Earth. This paper reviews some background of SCOSTEP and its past programs, achievements of the 5-year VarSITI program, and remaining outstanding questions after VarSITI.

Solar wind flow past Venus and its implications for the occurrence of the Kelvin–Helmholtz instability

2007 ◽  
Vol 55 (12) ◽  
pp. 1793-1803 ◽  
Author(s):  
H.K. Biernat ◽  
N.V. Erkaev ◽  
U.V. Amerstorfer ◽  
T. Penz ◽  
H.I.M. Lichtenegger
Keyword(s):  
Solar Wind ◽  
Wind Flow ◽  
Helmholtz Instability ◽  
Flow Past ◽  
Solar Wind Flow

Effects on the Jovian magnetosheath arising from solar wind flow around nonaxisymmetric bodies

1996 ◽  
Vol 101 (A5) ◽  
pp. 10665-10672 ◽  
Author(s):  
N. V. Erkaev ◽  
C. J. Farrugia ◽  
H. K. Biernat
Keyword(s):  
Solar Wind ◽  
Wind Flow ◽  
Solar Wind Flow

scholarly journals Cellular automata model of magnetospheric-ionospheric coupling

2003 ◽  
Vol 21 (9) ◽  
pp. 1931-1938 ◽  
Author(s):  
B. V. Kozelov ◽  
T. V. Kozelova
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Cellular Automata ◽  
Interplanetary Magnetic Field ◽  
Control Parameter ◽  
Energy Content ◽  
Nonlinear Phenomena ◽  
Cellular Automata Model ◽  
The Earth ◽  
Magnetospheric Tail

Abstract. We propose a cellular automata model (CAM) to describe the substorm activity of the magnetospheric-ionospheric system. The state of each cell in the model is described by two numbers that correspond to the energy content in a region of the current sheet in the magnetospheric tail and to the conductivity of the ionospheric domain that is magnetically connected with this region. The driving force of the system is supposed to be provided by the solar wind that is convected along the two boundaries of the system. The energy flux inside is ensured by the penetration of the energy from the solar wind into the array of cells (magnetospheric tail) with a finite velocity. The third boundary (near to the Earth) is closed and the fourth boundary is opened, thereby modeling the flux far away from the tail. The energy dissipation in the system is quite similar to other CAM models, when the energy in a particular cell exceeds some pre-defined threshold, and the part of the energy excess is redistributed between the neighbouring cells. The second number attributed to each cell mimics ionospheric conductivity that can allow for a part of the energy to be shed on field-aligned currents. The feedback between "ionosphere" and "magnetospheric tail" is provided by the change in a part of the energy, which is redistributed in the tail when the threshold is surpassed. The control parameter of the model is the z-component of the interplanetary magnetic field (Bz IMF), "frozen" into the solar wind. To study the internal dynamics of the system at the beginning, this control parameter is taken to be constant. The dynamics of the system undergoes several bifurcations, when the constant varies from - 0.6 to - 6.0. The Bz IMF input results in the periodic transients (activation regions) and the inter-transient period decreases with the decrease of Bz. At the same time the onset of activations in the array shifts towards the "Earth". When the modulus of the Bz IMF exceeds some threshold value, the transition takes place from periodic to chaotic dynamics. In the second part of the work we have chosen as the source the real values of the z-component of the interplanetary magnetic field taken from satellite observations. We have shown that in this case the statistical properties of the transients reproduce the characteristic features observed by Lui et al. (2000).Key words. Magnetospheric physics (magnetosphere-ionosphere interactions) – Space plasma physics (nonlinear phenomena)

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