Comparison of force-free flux rope models with observations of magnetic clouds

Vandas, M.; Romashets, E.; Watari, Shinichi; Geranios, A.; Antoniadou, E.; Zacharopoulou, O.

doi:10.1016/j.asr.2004.11.026

Cited by 29 publications

(29 citation statements)

References 15 publications

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“…We therefore believe that this is a correct and proper time-dependent generalization of the widely used stationary Lundquist model (Lundquist 1950). Vandas et al (2006Vandas et al ( , 2009 compared the generalized Lundquist model with observations and found good agreements between this classic model and the experimental data.…”

Section: Discussionmentioning

confidence: 99%

Investigation of dynamics of self-similarly evolving magnetic clouds

Dalakishvili

Rogava

Lapenta

et al. 2010

A&A

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Context. Magnetic clouds (MCs) are "magnetized plasma clouds" moving in the solar wind. MCs transport magnetic flux and helicity away from the Sun. These structures are not stationary but experience temporal evolution. Simplified MC models are usually considered. Aims. We investigate the dynamics of more general, radially expanding MCs. They are considered as cylindrically symmetric magnetic structures with low plasma β. Methods. We adopt both a self-similar approach method and a numerical approach. Results. We demonstrate that the forces are balanced in the considered self-similarly evolving, cylindrically symmetric magnetic structures. Explicit analytical expressions for magnetic field, plasma velocity, density, and pressure within MCs are derived. These solutions are characterized by conserved values of magnetic flux and helicity. We also investigate the dynamics of self-similarly evolving MCs by means of the numerical code "Graale". In addition, their expansion in a medium of higher density and higher plasma β is studied. It is shown that the physical parameters of the MCs maintain their self-similar character throughout their evolution. Conclusions. After comparing different self-similar and numerical solutions, we are able to conclude that the evolving MCs are quite adequately described by our self-similar solutions -they retain their self-similar, coherent nature for quite a long time and over large distances from the Sun.

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Section: Discussionmentioning

confidence: 99%

Investigation of dynamics of self-similarly evolving magnetic clouds

Dalakishvili

Rogava

Lapenta

et al. 2010

A&A

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“…(f) Marubashi and Lepping (2007) include curvature into the classic model. rope (Owens, Merkin, and Riley, 2006;Vandas and Romashets, 2003;Vandas et al, 2006;Démoulin and Dasso, 2009); non-cylindrical flux rope fitting (Mulligan and Russell, 2001;Owens et al, 2012); torus fitting Marubashi and Lepping, 2007). The Grad-Shafranov reconstruction technique (Hu and Sonnerup, 2002;) assumes a structure in magneto-hydrostatic (MHS) equilibrium with an invariant direction, and uses the Grad-Shafranov equation to describe the magnetic field in the structure.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Field Configuration Models and Reconstruction Methods for Interplanetary Coronal Mass Ejections

et al. 2013

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This study aims to provide a reference to different magnetic field models and reconstruction methods for interplanetary coronal mass ejections (ICMEs). In order to understand the differences in the outputs of those models and codes, we analyze 59 events from the Coordinated Data Analysis Workshop (CDAW) list, using four different magnetic field models and reconstruction techniques; force-free fitting (Goldstein, 1983; Burlaga, 1988;Lepping, Burlaga, and Jones, 1990), magnetostatic reconstruction using a numerical solution to the Grad-Shafranov equation (Hu and Sonnerup, 2001), fitting to a self-similarly expanding cylindrical configuration (Marubashi and Lepping, 2007) and elliptical, non-force free fitting (Hidalgo, 2003). The resulting parameters of the reconstructions for the 59 events are compared statistically, as well as in selected case studies. The ability of a method to fit or reconstruct an event is found to vary greatly: the Grad-Shafranov reconstruction is successful for most magnetic clouds (MCs) but for less than 10% of the non-MC ICMEs; the other three Al-Haddad et al methods provide a successful fit for more than 65% of all events. The differences between the reconstruction and fitting methods are discussed, and suggestions are proposed as to how to reduce them. We find that the magnitude of the axial field is relatively consistent across models but not the orientation of the axis of the ejecta. We also find that there are a few cases for which different signs of the magnetic helicity are found for the same event when we do not fix the boundaries, illustrating that this simplest of parameters is not necessarily always well constrained by fitting and reconstruction models. Finally, we look at three unique cases in depth to provide a comprehensive idea of the different aspects of how the fitting and reconstruction codes work.

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“…All of these considered a cylindrical cloud with circular (Cid et al 2002) or elliptical (Mulligan and Russell 2001) cross sections. Vandas et al (2006) proposed an elliptical cross section model with a force-free configuration. To date, there is no single model which can produce all the observed features of MCs.…”

Section: Interplanetary Spacementioning

confidence: 99%

Space Weather: Physics, Effects and Predictability

2010

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The time varying conditions in the near-Earth space environment that may affect space-borne or ground-based technological systems and may endanger human health or life are referred to as space weather. Space weather effects arise from the dynamic and highly variable conditions in the geospace environment starting from explosive events on the Sun (solar flares), Coronal Mass Ejections near the Sun in the interplanetary medium, and various energetic effects in the magnetosphere-ionosphere-atmosphere system. As the utilization of space has become part of our everyday lives, and as our lives have become increasingly dependent on technological systems vulnerable to the space weather influences, the understanding and prediction of hazards posed by these active solar events have grown in importance. In this paper, we review the processes of the Sun-Earth interactions, the dynamic conditions within the magnetosphere, and the predictability of space weather effects on radio waves, satellites and ground-based technological systems today.

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Comparison of force-free flux rope models with observations of magnetic clouds

Cited by 29 publications

References 15 publications

Investigation of dynamics of self-similarly evolving magnetic clouds

Investigation of dynamics of self-similarly evolving magnetic clouds

Magnetic Field Configuration Models and Reconstruction Methods for Interplanetary Coronal Mass Ejections

Space Weather: Physics, Effects and Predictability

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