Propagation of a spheromak: 1. Some comparisons of cylindrical and spherical magnetic clouds

Vandas, M.; Fischer, S.; Pelant, P.; Dryer, M.; Smith, Z.; Detman, T.

doi:10.1029/97ja02257

Cited by 33 publications

(27 citation statements)

References 29 publications

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“…noted that associated with this acceleration, the density jump becomes smaller. Lugaz et al (2005b) performed an in-depth analysis of the changes in the shock properties, dividing the interaction into four main phases: (i) before any physical interaction, when the shock propagates faster than an identical isolated shock due to the smaller density in the solar wind, (ii) during the shock propagation inside the magnetic cloud, when the shock speed in a rest frame increases and its compression ratio decreases, confirming the findings of , (iii) during the shock propagation inside the dense sheath when the shock decelerates, as pointed out by Vandas et al (1997), and (iv) the shock-shock merging when, as predicted by MHD theory, a stronger shock forms followed by a contact discontinuity. If the shock is weak or slow enough, it may dissipate as it propagates into the region of higher magnetosonic speed inside the magnetic cloud (Xiong et al 2006;.…”

Section: Changes In the Shock Propertiessupporting

confidence: 75%

“…These observations and numerical simulations confirmed that the radial extent of the leading CME plateaus during the main phase (i.e. when the speed of both CMEs changes significantly) of interaction (Schmidt and Cargill 2004;Lugaz et al 2005bXiong et al 2006) and this is typically associated with a "pancaking" of the leading CME (Vandas et al 1997). In Lugaz et al (2005b), the authors discussed how the shock propagation through the leading CME is the main way in which the expansion slows.…”

Section: Compression and Reconnection Between Cmessupporting

confidence: 66%

“…Most of what is known about the changes in shock properties was learned from numerical simulations; however, there have been many reported detections of shocks propagating inside a magnetic cloud or magnetic ejecta at 1 AU (Wang et al 2003c;Collier et al 2007;Richardson and Cane 2010a;Liu et al , 2014cLugaz et al 2015. Vandas et al (1997) noted that a shock propagates faster inside a magnetic cloud due to the enhanced fast magnetosonic speed inside, which may result in shock-shock merging close to the nose of the magnetic cloud but two distinct shocks in the flanks. noted that associated with this acceleration, the density jump becomes smaller.…”

Section: Changes In the Shock Propertiesmentioning

confidence: 99%

“…The authors concluded that "the interaction between two fast flows, is in general a nonlinear process, and hence, a compound stream is more than a linear superposition of its parts". An early numerical investigation is that of Vandas et al (1997), who simulated the interaction of a shock wave with a magnetic cloud in 2.5-D MHD. The authors noted that the shock propagation results in a radial compression of the magnetic cloud, a change of its aspect ratio, and acceleration as well as heating of the cloud.…”

Section: Plasma Evolutionmentioning

confidence: 99%

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The Physical Processes of CME/ICME Evolution

et al. 2017

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As observed in Thomson-scattered white light, coronal mass ejections (CMEs) are manifest as large-scale expulsions of plasma magnetically driven from the corona in the most energetic eruptions from the Sun. It remains a tantalizing mystery as to how these erupting magnetic fields evolve to form the complex structures we observe in the solar wind at Earth. Here, we strive to provide a fresh perspective on the post-eruption and interplanetary evolution of CMEs, focusing on the physical processes that define the many complex interactions of the ejected plasma with its surroundings as it departs the corona and propagates through the heliosphere. We summarize the ways CMEs and their interplanetary CMEs (ICMEs) are rotated, reconfigured, deformed, deflected, decelerated and disguised during their journey through the solar wind. This study then leads to consideration of how structures originating in coronal eruptions can be connected to their far removed interplanetary counterparts. Given that ICMEs are the drivers of most geomagnetic storms (and the sole driver of extreme storms), this work provides a guide to the processes that must be considered in making space weather forecasts from remote observations of the corona.

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Section: Changes In the Shock Propertiessupporting

confidence: 75%

Section: Compression and Reconnection Between Cmessupporting

confidence: 66%

Section: Changes In the Shock Propertiesmentioning

confidence: 99%

Section: Plasma Evolutionmentioning

confidence: 99%

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The Physical Processes of CME/ICME Evolution

et al. 2017

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“…According to the formulas given in this reference, the radius of curvature of the ICME nose in this case must be ∼ < 0.1 AU for each of the X and Y ICME dimensions with any Mach number M > 1. This radius of curvature is consistent with the ICME geometry discussed in the preceding paragraph and the conclusion of Vandas et al (1997) related to a spheromak.…”

Section: Interplanetary Datasupporting

confidence: 73%

A Challenging Solar Eruptive Event of 18 November 2003 and the Causes of the 20 November Geomagnetic Superstorm. IV. Unusual Magnetic Cloud and Overall Scenario

et al. 2014

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The geomagnetic superstorm of 20 November 2003 with Dst = −422 nT, one of the most intense in history, is not well understood. The superstorm was caused by a moderate solar eruptive event on 18 November, comprehensively studied in our preceding Papers I -III. The analysis has shown a number of unusual and extremely complex features, which presumably led to the formation of an isolated right-handed magnetic-field configuration. Here we analyze the interplanetary disturbance responsible for the 20 November superstorm, compare some of its properties with the extreme 28 -29 October event, and reveal a compact size of the magnetic cloud (MC) and its disconnection from the Sun. Most likely, the MC had a spheromak configuration and expanded in a narrow angle of ≤ 14• . A very strong magnetic field in the MC up to 56 nT was due to the unusually weak expansion of the disconnected spheromak in an enhanced-density environment constituted by the tails of the preceding ICMEs. Additional circumstances favoring the superstorm were (i) the exact impact of the spheromak on the Earth's magnetosphere and (ii) the almost exact southward orientation of the magnetic field, corresponding to the original orientation in its probable source region near the solar disk center.

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Magnetohydrodynamic simulation of interplanetary propagation of multiple coronal mass ejections with internal magnetic flux rope (SUSANOO‐CME)

2016

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Coronal mass ejections (CMEs) are the most important drivers of various types of space weather disturbance. Here we report a newly developed magnetohydrodynamic (MHD) simulation of the solar wind, including a series of multiple CMEs with internal spheromak‐type magnetic fields. First, the polarity of the spheromak magnetic field is set as determined automatically according to the Hale‐Nicholson law and the chirality law of Bothmer and Schwenn. The MHD simulation is therefore capable of predicting the time profile of the southward interplanetary magnetic field at the Earth, in relation to the passage of a magnetic cloud within a CME. This profile is the most important parameter for space weather forecasts of magnetic storms. In order to evaluate the current ability of our simulation, we demonstrate a test case: the propagation and interaction process of multiple CMEs associated with the highly complex active region NOAA 10486 in October to November 2003, and present the result of a simulation of the solar wind parameters at the Earth during the 2003 Halloween storms. We succeeded in reproducing the arrival at the Earth's position of a large amount of southward magnetic flux, which is capable of causing an intense magnetic storm. We find that the observed complex time profile of the solar wind parameters at the Earth could be reasonably well understood by the interaction of a few specific CMEs.

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Propagation of a spheromak: 1. Some comparisons of cylindrical and spherical magnetic clouds

Cited by 33 publications

References 29 publications

The Physical Processes of CME/ICME Evolution

The Physical Processes of CME/ICME Evolution

A Challenging Solar Eruptive Event of 18 November 2003 and the Causes of the 20 November Geomagnetic Superstorm. IV. Unusual Magnetic Cloud and Overall Scenario

Magnetohydrodynamic simulation of interplanetary propagation of multiple coronal mass ejections with internal magnetic flux rope (SUSANOO‐CME)

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