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

2019 ◽  
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.

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

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

<p>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 10â—¦ rotation of the magnetic field over the hole, slowly decreases from Mercury to Earth. The pseudo magnetic holes, defined as a rotation between 10â—¦ and 45â—¦ 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<br>or outside of Venus’s orbit.</p>

scholarly journals On the magnetic characteristics of magnetic holes in the solar wind between Mercury and Venus

2020 ◽  
Vol 38 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Martin Volwerk ◽  
Charlotte Goetz ◽  
Ferdinand Plaschke ◽  
Tomas Karlsson ◽  
Daniel Heyner ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Occurrence Rate ◽  
Magnetic Characteristics ◽  
The Magnetic Field

Abstract. The occurrence rate of linear and pseudo magnetic holes has been determined during MESSENGER's cruise phase starting from Venus (2007) 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 Venus. The pseudo magnetic holes, defined as a rotation between 10 and 45∘ over the hole, have mostly a constant occurrence rate.

scholarly journals The evolution of inverted magnetic fields through the inner heliosphere

2020 ◽  
Vol 494 (3) ◽  
pp. 3642-3655 ◽  
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.

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

2010 ◽  
Vol 28 (9) ◽  
pp. 1695-1702 ◽  
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.

scholarly journals Statistical study of foreshock cavitons

2013 ◽  
Vol 31 (12) ◽  
pp. 2163-2178 ◽  
Author(s):  
P. Kajdič ◽  
X. Blanco-Cano ◽  
N. Omidi ◽  
K. Meziane ◽  
C. T. Russell ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Statistical Study ◽  
Low Frequency ◽  
Bow Shock ◽  
Occurrence Rate ◽  
Time Intervals ◽  
Distinct Structure ◽  
Wide Range ◽  
The Magnetic Field

Abstract. In this work we perform a statistical analysis of 92 foreshock cavitons observed with the Cluster spacecraft 1 during the period 2001–2006. We analyze time intervals during which the spacecraft was located in the Earth's foreshock with durations longer than 10 min. Together these amount to ~ 50 days. The cavitons are transient structures in the Earth's foreshock. Their main signatures in the data include simultaneous depletions of the magnetic field intensity and plasma density, which are surrounded by a rim of enhanced values of these two quantities. Cavitons form due to nonlinear interaction of transverse and compressive ultra-low frequency (ULF) waves and are therefore always surrounded by intense compressive ULF fluctuations. They are carried by the solar wind towards the bow shock. This work represents the first systematic study of a large sample of foreshock cavitons. We find that cavitons appear for a wide range of solar wind and interplanetary magnetic field conditions and are therefore a common feature upstream of Earth's quasi-parallel bow shock with an average occurrence rate of ~ 2 events per day. We also discuss their observational properties in the context of other known upstream phenomena and show that the cavitons are a distinct structure in the foreshock.

scholarly journals Steepening of magnetosonic waves in the inner coma of comet 67P/Churyumov–Gerasimenko

2021 ◽  
Vol 39 (4) ◽  
pp. 721-742
Author(s):  
Katharina Ostaszewski ◽  
Karl-Heinz Glassmeier ◽  
Charlotte Goetz ◽  
Philip Heinisch ◽  
Pierre Henri ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Interaction Region ◽  
Occurrence Rate ◽  
Solar Wind Interaction ◽  
Background Magnetic Field ◽  
The Waves ◽  
Comet 67P ◽  
The Magnetic Field ◽  
Field Enhancements

Abstract. We present a statistical survey of large-amplitude, asymmetric plasma and magnetic field enhancements detected outside the diamagnetic cavity at comet 67P/Churyumov–Gerasimenko from December 2014 to June 2016. Based on the concurrent observations of plasma and magnetic field enhancements, we interpret them to be magnetosonic waves. The aim is to provide a general overview of these waves' properties over the mission duration. As the first mission of its kind, the ESA Rosetta mission was able to study the plasma properties of the inner coma for a prolonged time and during different stages of activity. This enables us to study the temporal evolution of these waves and their characteristics. In total, we identified ∼ 70 000 steepened waves in the magnetic field data by means of machine learning. We observe that the occurrence of these steepened waves is linked to the activity of the comet, where steepened waves are primarily observed at high outgassing rates. No clear indications of a relationship between the occurrence rate and solar wind conditions were found. The waves are found to propagate predominantly perpendicular to the background magnetic field, which indicates their compressional nature. Characteristics like amplitude, skewness, and width of the waves were extracted by fitting a skew normal distribution to the magnetic field magnitude of individual steepened waves. With increasing mass loading, the average amplitude of the waves decreases, while the skewness increases. Using a modified 1D magnetohydrodynamic (MHD) model, we investigated if the waves can be described by the combination of nonlinear and dissipative effects. By combining the model with observations of amplitude, width and skewness, we obtain an estimate of the effective plasma diffusivity in the comet–solar wind interaction region and compare it with suitable reference values as a consistency check. At 67P/Churyumov–Gerasimenko, these steepened waves are of particular importance as they dominate the innermost interaction region for intermediate to high activity.

Magnetospheric response to solar wind driving

2021 ◽  
Author(s):  
Tatiana Výbošťoková ◽  
Zdeněk Němeček ◽  
Jana Šafránková
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Electric Field ◽  
Geomagnetic Storms ◽  
Interplanetary Space ◽  
Time Lags ◽  
Interplanetary Shocks ◽  
Geomagnetic Indices ◽  
The Earth ◽  
The Magnetic Field

<p>Interaction of solar events propagating throughout the interplanetary space with the magnetic field of the Earth may result in disruption of the magnetosphere. Disruption of the magnetic field is followed by the formation of the time-varying electric field and thus electric current is induced in Earth-bound structures such as transmission networks, pipelines or railways. In that case, it is necessary to be able to predict a future state of the magnetosphere and magnetic field of the Earth. The most straightforward way would use geomagnetic indices. Several studies are investigating the relationship of the response of the magnetosphere to changes in the solar wind with motivation to give a more accurate prediction of geomagnetic indices during geomagnetic storms. To forecast these indices, different approaches have been attempted--from simple correlation studies to neural networks.</p><p>We study the effects of interplanetary shocks observed at L1 on the Earth's magnetosphere with a database of tens of shocks between 2009 and 2019. Driving the magnetosphere is described as integral of reconnection electric field for each shock. The response of the geomagnetic field is described with the SYM-H index. We created an algorithm in Python for prediction of the magnetosphere state based on the correlation of solar wind driving and magnetospheric response and found that typical time-lags range between tens of minutes to maximum 2 hours. The results are documented by a large statistical study.</p>

scholarly journals Steepening of magnetosonic waves in the inner coma of comet 67P/Churyumov-Gerasimenko

2020 ◽  
Author(s):  
Katharina Ostaszewski ◽  
Karl-Heinz Glassmeier ◽  
Charlotte Goetz ◽  
Philip Heinisch ◽  
Pierre Henri ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Interaction Region ◽  
Occurrence Rate ◽  
Solar Wind Interaction ◽  
Plasma Properties ◽  
Background Magnetic Field ◽  
The Waves ◽  
Comet 67P ◽  
The Magnetic Field

Abstract. We present a statistical survey of large amplitude, asymmetric plasma, and magnetic field enhancements at comet 67P/Churyumov-Gerasimenko from December 2014 to June 2016. The aim is to provide a general overview of these structures' properties over the mission duration. At comets, nonlinear wave evolution plays an integral part in the development of turbulence and in particular facilitates the transfer of energy and momentum. As the first mission of its kind, the ESA Rosetta mission was able to study the plasma properties of the inner coma for a prolonged time and during different stages of activity. This enables us to study the temporal evolution of steepened waves and their characteristics. In total, we identified ~70000 events in the magnetic field data by means of machine learning. We observe that the occurrence of wave events is linked to the activity of the comet, where events are primarily observed at high outgassing rates. No clear indications of a relationship between the occurrence rate and solar wind conditions were found. The waves are found to propagate predominantly perpendicular to the background magnetic field, which indicates their compressive nature. Characteristics like amplitude, skewness, and width of the waves were extracted by fitting a skew normal distribution to the magnetic field magnitude of individual events. With increasing massloading the average amplitude of steepened waves decreases while the skewness increases. Using a modified 1D MHD model it was possible to show that such solitary structures can be described by the combination of nonlinear, dispersive, and dissipative effects. By combining the model with observations of amplitude, width, and skewness we obtain an estimate of the effective plasma viscosity in the comet-solar wind interaction region. At 67P/Churyumov-Gerasimenko steepened waves are of particular importance as they dominate the innermost interaction region for intermediate to high activity.

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.

Nanoscale Dust Production at 1 Au; Identification and Tracking with 12 Spacecraft

2020 ◽  
Author(s):  
Hairong Lai ◽  
Yingdong Jia ◽  
Martin Connors ◽  
Christopher Russell
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Enhancement ◽  
Solar Radius ◽  
The Sun ◽  
The Earth ◽  
Complete Test ◽  
Spacecraft Data ◽  
The Magnetic Field ◽  
Field Enhancements

<p>Interplanetary Field Enhancements are phenomena in the interplanetary magnetic field, first discovered near Venus, during an extremely long duration (12 hours) and large size (about 0.1 AU) passage across the Pioneer Venus spacecraft. Three and a half hours later and 21 x 10<sup>6</sup> km farther from the Sun, this structure, somewhat weaker and off to the side of the expected radial path of any solar initiated disturbance, was seen by first Venera 13 and then Venera 14, trailing behind V13. Since this discovery, many smaller such disturbances have been observed and attributed to collisions of small rocks in space at speeds of about 20 km/s at 1 AU and faster, closer to the Sun. All sightings with magnetometers and other space plasma instruments give very precise measurements of the radial structure (of usually the magnetic field), but the scale transverse to the solar radius is poorly defined, as is the temporal evolution of the structure from single spacecraft data.</p><p>On January 16, 2018, near Earth, 12 spacecraft equipped with plasma spectrometers and magnetometers observed the passage of a single Interplanetary Field Enhancement. The magnetic field profiles at the four 1 AU spacecraft were very similar. The profiles were obtained at different times appropriate to their locations. The 4 Cluster spacecraft were closer to the Earth and in a region in which the solar wind had slowed down because of the Earth’s bow wave (shock) in the solar wind. The disturbance in the shocked solar wind occurred at the time expected if the IFE structure had not been slowed by the plasma, but rather had proceeded with the momentum it had prior to the shock crossing. If the disturbance causing particles are small bits of rock (not protons), then they should have kept most of their momentum in crossing the bow shock. We view this as a complete test of the dust producing collisional origin of these Interplanetary Field Enhancements, and a clear demonstration of how the solar wind clears out the dust in the inner solar system produced by the continuing destructive collisional process.</p>

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