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

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.

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(Non)-radial propagation of the solar wind flow

10.5194/egusphere-egu2020-2736 ◽

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

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.

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The evolution of inverted magnetic fields through the inner heliosphere

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa951 ◽

2020 ◽

Vol 494 (3) ◽

pp. 3642-3655 ◽

Cited By ~ 2

Author(s):

Allan R Macneil ◽

Mathew J Owens ◽

Robert T Wicks ◽

Mike Lockwood ◽

Sarah N Bentley ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Radial Distance ◽

Occurrence Rate ◽

Slow Solar Wind ◽

The Sun ◽

Radial Evolution ◽

In Transit ◽

The Magnetic Field ◽

Inner Heliosphere

ABSTRACT Local inversions are often observed in the heliospheric magnetic field (HMF), but their origins and evolution are not yet fully understood. Parker Solar Probe has recently observed rapid, Alfvénic, HMF inversions in the inner heliosphere, known as ‘switchbacks’, which have been interpreted as the possible remnants of coronal jets. It has also been suggested that inverted HMF may be produced by near-Sun interchange reconnection; a key process in mechanisms proposed for slow solar wind release. These cases suggest that the source of inverted HMF is near the Sun, and it follows that these inversions would gradually decay and straighten as they propagate out through the heliosphere. Alternatively, HMF inversions could form during solar wind transit, through phenomena such velocity shears, draping over ejecta, or waves and turbulence. Such processes are expected to lead to a qualitatively radial evolution of inverted HMF structures. Using Helios measurements spanning 0.3–1 au, we examine the occurrence rate of inverted HMF, as well as other magnetic field morphologies, as a function of radial distance r, and find that it continually increases. This trend may be explained by inverted HMF observed between 0.3 and 1 au being primarily driven by one or more of the above in-transit processes, rather than created at the Sun. We make suggestions as to the relative importance of these different processes based on the evolution of the magnetic field properties associated with inverted HMF. We also explore alternative explanations outside of our suggested driving processes which may lead to the observed trend.

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Cluster-C1 observations on the geometrical structure of linear magnetic holes in the solar wind at 1 AU

Annales Geophysicae ◽

10.5194/angeo-28-1695-2010 ◽

2010 ◽

Vol 28 (9) ◽

pp. 1695-1702 ◽

Cited By ~ 27

Author(s):

T. Xiao ◽

Q. Q. Shi ◽

T. L. Zhang ◽

S. Y. Fu ◽

L. Li ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Geometrical Structure ◽

Occurrence Rate ◽

Geometrical Shape ◽

Magnetic Field Data ◽

Magnetic Field Magnitude ◽

The Relationship ◽

Plasma Measurements ◽

The Magnetic Field

Abstract. Interplanetary linear magnetic holes (LMHs) are structures in which the magnetic field magnitude decreases with little change in the field direction. They are a 10–30% subset of all interplanetary magnetic holes (MHs). Using magnetic field and plasma measurements obtained by Cluster-C1, we surveyed the LMHs in the solar wind at 1 AU. In total 567 interplanetary LMHs are identified from the magnetic field data when Cluster-C1 was in the solar wind from 2001 to 2004. We studied the relationship between the durations and the magnetic field orientations, as well as that of the scales and the field orientations of LMHs in the solar wind. It is found that the geometrical structure of the LMHs in the solar wind at 1 AU is consistent with rotational ellipsoid and the ratio of scales along and across the magnetic field is about 1.93:1. In other words, the structure is elongated along the magnetic field at 1 AU. The occurrence rate of LMHs in the solar wind at 1 AU is about 3.7 per day. It is shown that not only the occurrence rate but also the geometrical shape of interplanetary LMHs has no significant change from 0.72 AU to 1 AU in comparison with previous studies. It is thus inferred that most of interplanetary LMHs observed at 1 AU are formed and fully developed before 0.72 AU. The present results help us to study the formation mechanism of the LMHs in the solar wind.

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On the magnetic characteristics of magnetic holes in the solar wind between Mercury and Earth

10.5194/angeo-2019-127 ◽

2019 ◽

Cited By ~ 1

Author(s):

Martin Volwerk ◽

Charlotte Goetz ◽

Ferdinand Plaschke ◽

Tomas Karlsson ◽

Daniel Heyner

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Occurrence Rate ◽

Magnetic Characteristics ◽

The Earth ◽

The Magnetic Field

Abstract. The occurrence rate of linear and pseudo magnetic holes has been determined during MESSENGER's cruise phase starting from Earth (2005) and arriving at Mercury (2011). It is shown that the occurrence rate of linear magnetic holes, defined as a maximum of 10° rotation of the magnetic field over the hole, slowly decreases from Mercury to Earth. The pseudo magnetic holes, defined as a rotation between 10° and 45° over the hole, have mostly a constant occurrence rate, with a slight increase in front of the Earth and a decrease around the Earth. The width and depth of these structures seem to strongly differ depending on whether they are inside or outside of Venus's orbit.

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Investigation of the magnetic field between the shock wave and the obstacle in the solar wind flow around a planet

Advances in Space Research ◽

10.1016/0273-1177(81)90092-2 ◽

1981 ◽

Vol 1 (1) ◽

pp. 101-104

Author(s):

V.B. Boranov ◽

E.G. Eroshenko ◽

M.D. Kartalev ◽

I.P. Mastikov

Keyword(s):

Magnetic Field ◽

Shock Wave ◽

Solar Wind ◽

Wind Flow ◽

Solar Wind Flow ◽

The Magnetic Field

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On the magnetic characteristics of magnetic holes in the solar wind between Mercury and Earth

10.5194/egusphere-egu2020-22 ◽

2020 ◽

Author(s):

Martin Volwerk ◽

Charlotte Goetz ◽

Ferdinand Plaschke ◽

Tomas Karlsson ◽

Daniel Heyner

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Occurrence Rate ◽

Magnetic Characteristics ◽

The Earth ◽

The Magnetic Field

The occurrence rate of linear and pseudo magnetic holes has been determined during MESSENGER&#8217;s cruise phase starting from Earth (2005) and arriving at Mercury (2011). It is shown that the occurrence rate of linear magnetic holes, defined as a maximum of 10&#226;&#151;&#166; rotation of the magnetic field over the hole, slowly decreases from Mercury to Earth. The pseudo magnetic holes, defined as a rotation between 10&#226;&#151;&#166; and 45&#226;&#151;&#166; over the hole, have mostly a constant occurrence rate, with a slight increas in front of the Earth and a decrease around the Earth. The width and depth of these structures seem to strongly differ depending on whether they are inside or outside of Venus&#8217;s orbit.

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An optimization principle for computing stationary MHD equilibria with solar wind flow

10.5194/egusphere-egu2020-3029 ◽

2020 ◽

Author(s):

Thomas Wiegelmann ◽

Thomas Neukirch ◽

Dieter Nickeler ◽

Iulia Chifu

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Coronal Magnetic Field ◽

Field Vector ◽

Source Surface ◽

Solar Chromosphere ◽

Wind Flow ◽

Solar Wind Flow ◽

Nonlinear Force ◽

The Magnetic Field

Knowledge about the magnetic field and plasma environment is important for almost all physical processes in the solar atmosphere. Precise measurements of the magnetic field vector are done routinely only in the photosphere, e.g. by SDO/HMI. These measurements are used as boundary condition for modelling the solar chromosphere and corona, whereas some model assumptions have to be made. In the low-plasma-beta corona the Lorentz-force vanishes and the magnetic field is reconstructed with a nonlinear force-free model. In the mixed-beta chromosphere plasma forces have to be taken into account with the help of a magnetostatic model. And finally for modelling the global corona far beyond the source surface the solar wind flow has to be incorporated within a stationary MHD model. To do so, we generalize a nonlinear force-free and magneto-static optimization code by the inclusion of a field aligned compressible plasma flow. Applications are the implementation of the solar wind on global scale. This allows to reconstruct the coronal magnetic field further outwards than with potential field, nonlinear force-free and magneto-static models. This way the model might help in future to provide the magnetic connectivity for joint observations of remote sensing and in-situ instruments on Solar Orbiter and Parker Solar Probe.

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Plasma processes at comet Churyumov–Gerasimenko: Expectations for Rosetta

Journal of Plasma Physics ◽

10.1017/s0022377813001116 ◽

2013 ◽

Vol 79 (6) ◽

pp. 1067-1070 ◽

Cited By ~ 1

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.

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