Spheroidal models of magnetic clouds and their comparison with spacecraft measurements

Vandas, M.; Fischer, S.; Pelant, P.; Geranios, A.

doi:10.1029/93ja00055

Cited by 54 publications

(31 citation statements)

References 13 publications

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“…Chen, 1996;Kumar and Rust, 1996;Vandas et al, 1993), it is numerical simulations that have shed the most light on the dynamics of ICMEs. We focus here on such simulations.…”

Section: Results From Numerical Modelsmentioning

confidence: 99%

Modelling interplanetary CMEs using magnetohydrodynamic simulations

Cargill

Schmidt

2002

Ann. Geophys.

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Abstract. The dynamics of Interplanetary Coronal MassEjections (ICMEs) are discussed from the viewpoint of numerical modelling. Hydrodynamic models are shown to give a good zero-order picture of the plasma properties of ICMEs, but they cannot model the important magnetic field effects. Results from MHD simulations are shown for a number of cases of interest. It is demonstrated that the strong interaction of the ICME with the solar wind leads to the ICME and solar wind velocities being close to each other at 1 AU, despite their having very different speeds near the Sun. It is also pointed out that this interaction leads to a distortion of the ICME geometry, making cylindrical symmetry a dubious assumption for the CME field at 1 AU. In the presence of a significant solar wind magnetic field, the magnetic fields of the ICME and solar wind can reconnect with each other, leading to an ICME that has solar wind-like field lines. This effect is especially important when an ICME with the right sense of rotation propagates down the heliospheric current sheet. It is also noted that a lack of knowledge of the coronal magnetic field makes such simulations of little use in space weather forecasts that require knowledge of the ICME magnetic field strength.

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“…Chen, 1996;Kumar and Rust, 1996;Vandas et al, 1993), it is numerical simulations that have shed the most light on the dynamics of ICMEs. We focus here on such simulations.…”

Section: Results From Numerical Modelsmentioning

confidence: 99%

Modelling interplanetary CMEs using magnetohydrodynamic simulations

Cargill

Schmidt

2002

Ann. Geophys.

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“…Some of these models obtained a better fit of the field intensity in a MC/flux rope than the Lepping et al (1990) model; for other recent MC/flux rope models see Sonnerup (2001, 2002); Hidalgo et al (2002); Hidalgo (2003); Li et al (2001); Mulligan et al (1999);and Vandas et al (2005a, b). The cylindrical force free flux rope model for MCs has been challenged via comparison with spheroidal models (spherical, oblate, and prolate) by Vandas et al (1993). In particular, they found that for 14 structures considered, primarily from IMP data, the spheroidal model fits were of comparable accuracy to the cylindrical model fits, but the estimated diameters were generally larger for the spheroidal models.…”

Section: Summary and Discussionmentioning

confidence: 99%

A summary of WIND magnetic clouds for years 1995-2003: model-fitted parameters, associated errors and classifications

Lepping¹,

Berdichevsky²,

Wu³

et al. 2006

Ann. Geophys.

189

267

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Abstract.Interplanetary magnetic clouds (MCs) have been identified for the first 8.6 years of the WIND mission, and their magnetic field structures have been parameter-fitted by a static, force free, cylindrically-symmetric model ) with various levels of success. This paper summarizes various aspects of the results of the model fitting by providing: seven estimated model fit-parameter values for each of the 82 MCs found, their objectively determined quality estimates, closest approach vectors (in two coordinate frames), fit-parameter errors for the cases of acceptable quality (50 cases, or 61%), axial magnetic fluxes, axial current densities, and total axial current -as well as some examples of MC profiles for various conditions and "categories" for each case (e.g. B z : N→S or S→N, etc.). MC quality is estimated from a quantitative consideration of a large set of parameters, such as the chi-squared of the model fit, degree of asymmetry of the B profile, and a comparison of two means of estimating radius. This set of MCs was initially identified by visual inspection of relevant field and plasma data. Each resulting MC candidate is then tested through the use of the MC parameter model, for various adjusted durations to determine the best fit, which helps to refine the boundarytimes. The resulting MC set is called Set 1. Another, larger, set (Set 2) of MCs is identified through an automated program whose criteria are based on general MC plasma and field characteristics at 1 AU determined through past experience. Set 1 is almost fully contained within Set 2, whose frequency of occurrence better matches that of the sunspot cycle than Set 1. The difference-set (Set 2-Set 1) is referred to as the magnetic cloud-like (MCL) set, whose members do not very well represent good flux ropes through modeling. We present a discussion of how a MC's front boundary isCorrespondence to: R. P. Lepping (ronald.p.lepping@nasa.gov) specifically identified in terms of multi-parameter considerations (i.e. any one or more of: increase in B, directional discontinuity, magnetic hole in B, drop in proton plasma beta, B-fluctuation level change, proton temperature drop, etc.), as well as through the application of the flux rope model. Also presented are examples of unusual MCs, as well as some commonly occurring relationships, such as the existence and frequency (approx. 1/2 the time) of upstream interplanetary shocks, and less frequent internal shocks.

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“…15d. Spheroidal models can fit the magnetic field data as well as the flux rope models and capture many com- Marubashi and Lepping (2007), copyright by the authors; panel (d) from Vandas et al (1993), copyright by AGU plexities of the magnetic field profiles, such as sinusoidal, double peaked and plateau type profiles (e.g., Vandas et al 1993). However, as mentioned above, observations give strong support for flux ropes curving back and being attached to the Sun, and as shown before, when the expansion and elliptical cross-sections are allowed, flux rope models can also explain many of the asymmetries.…”

Section: Global Structure Of Magnetic Clouds From Modellingmentioning

confidence: 99%

Coronal mass ejections and their sheath regions in interplanetary space

Kilpua

Koskinen

Pulkkinen

2017

Living Rev Sol Phys

359

360

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Interplanetary coronal mass ejections (ICMEs) are large-scale heliospheric transients that originate from the Sun. When an ICME is sufficiently faster than the preceding solar wind, a shock wave develops ahead of the ICME. The turbulent region between the shock and the ICME is called the sheath region. ICMEs and their sheaths and shocks are all interesting structures from the fundamental plasma physics viewpoint. They are also key drivers of space weather disturbances in the heliosphere and planetary environments. ICME-driven shock waves can accelerate charged particles to high energies. Sheaths and ICMEs drive practically all intense geospace storms at the Earth, and they can also affect dramatically the planetary radiation environments and atmospheres. This review focuses on the current understanding of observational signatures and properties of ICMEs and the associated sheath regions based on five decades of studies. In addition, we discuss modelling of ICMEs and many fundamental outstanding questions on their origin, evolution and effects, largely due to the limitations of single spacecraft observations of these macro-scale structures. We also present current understanding of space weather consequences of these large-scale solar wind structures, including effects at the other Solar System planets and exoplanets. We specially emphasize the different origin, properties and consequences of the sheaths and ICMEs.

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Spheroidal models of magnetic clouds and their comparison with spacecraft measurements

Cited by 54 publications

References 13 publications

Modelling interplanetary CMEs using magnetohydrodynamic simulations

Modelling interplanetary CMEs using magnetohydrodynamic simulations

A summary of WIND magnetic clouds for years 1995-2003: model-fitted parameters, associated errors and classifications

Coronal mass ejections and their sheath regions in interplanetary space

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