Multiple, distant (40°) in situ observations of a magnetic cloud and a corotating interaction region complex

Farrugia, C. J.; Berdichevsky, D. B.; Möstl, Christian; Galvin, A. B.; Leitner, M.; Popecki, M. A.; Simunac, K. D. C.; Opitz, A.; Lavraud, B.; Ogilvie, K. W.; Veronig, Astrid; Temmer, Manuela; Luhmann, J. G.; Sauvaud, J. A.

doi:10.1016/j.jastp.2010.09.011

Cited by 64 publications

(96 citation statements)

References 73 publications

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“…The assumption of invariance along the cloud axis is also made in all the other fitting techniques used in this article. Other recent observations pointing towards a more complicated geometry of ICMEs at 1 AU have been made by Kahler, Krucker, and Szabo (2011) and Farrugia et al (2011).…”

Section: Introductionmentioning

confidence: 85%

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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Section: Introductionmentioning

confidence: 85%

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

et al. 2013

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“…1). As such, we do not consider nonplanar MC axis, as suggested by Farrugia et al (2011) for the observations of one MC by three spacecraft. This would require a A50, page 8 of 13 Fig.…”

Section: Methodsmentioning

confidence: 99%

Global axis shape of magnetic clouds deduced from the distribution of their local axis orientation

Janvier

Démoulin

Dasso

2013

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Context. Coronal mass ejections (CMEs) are routinely tracked with imagers in the interplanetary space, while magnetic clouds (MCs) properties are measured locally by spacecraft. However, both imager and in situ data do not provide any direct estimation of the general flux rope properties. Aims. The main aim of this study is to constrain the global shape of the flux rope axis from local measurements and to compare the results from in-situ data with imager observations. Methods. We performed a statistical analysis of the set of MCs observed by WIND spacecraft over 15 years in the vicinity of Earth. We analyzed the correlation between different MC parameters and studied the statistical distributions of the angles defining the local axis orientation. With the hypothesis of having a sample of MCs with a uniform distribution of spacecraft crossing along their axis, we show that a mean axis shape can be derived from the distribution of the axis orientation. As a complement, while heliospheric imagers do not typically observe MCs but only their sheath region, we analyze one event where the flux rope axis can be estimated from the STEREO imagers.Results. From the analysis of a set of theoretical models, we show that the distribution of the local axis orientation is strongly affected by the overall axis shape. Next, we derive the mean axis shape from the integration of the observed orientation distribution. This shape is robust because it is mostly determined from the overall shape of the distribution. Moreover, we find no dependence on the flux rope inclination on the ecliptic. Finally, the derived shape is fully consistent with the one derived from heliospheric imager observations of the June 2008 event. Conclusions. We have derived a mean shape of MC axis that only depends on one free parameter, the angular separation of the legs (as viewed from the Sun). This mean shape can be used in various contexts, such as studies of high-energy particles or space weather forecasts.

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“…Indeed, recent studies led by different authors have reached different conclusions on the axis shape even when analysing the same multi-spacecraft data of a MC observed with favorable conditions. For example, the opposite results of Farrugia et al (2011) and Ruffenach et al (2012) on the axis shape are compared in Fig. 3 of Démoulin (2014).…”

Section: Quantitative Generic Icme Structurementioning

confidence: 99%

Quantitative model for the generic 3D shape of ICMEs at 1 AU

Démoulin

Janvier

Masías-Meza

et al. 2016

A&A

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Context. Interplanetary imagers provide 2D projected views of the densest plasma parts of interplanetary coronal mass ejections (ICMEs) while in situ measurements provide magnetic field and plasma parameter measurements along the spacecraft trajectory, so along a 1D cut. As such, the data only give a partial view of their 3D structures. Aims. By studying a large number of ICMEs, crossed at different distances from their apex, we develop statistical methods to obtain a quantitative generic 3D shape of ICMEs. Methods. In a first approach we theoretically obtain the expected statistical distribution of the shock-normal orientation from assuming simple models of 3D shock shapes, including distorted profiles, and compare their compatibility with observed distributions. In a second approach we use the shock normal and the flux rope axis orientations, as well as the impact parameter, to provide statistical information across the spacecraft trajectory. Results. The study of different 3D shock models shows that the observations are compatible with a shock symmetric around the Sunapex line as well as with an asymmetry up to an aspect ratio around 3. Moreover, flat or dipped shock surfaces near their apex can only be rare cases. Next, the sheath thickness and the ICME velocity have no global trend along the ICME front. Finally, regrouping all these new results and the ones of our previous articles, we provide a quantitative ICME generic 3D shape, including the global shape of the shock, the sheath and the flux rope.Conclusions. The obtained quantitative generic ICME shape will have implications for several aims. For example, it constrains the output of typical ICME numerical simulations. It is also a base to develop deeper studies of the transport of high energy solar and cosmic particles during an ICME propagation, as well as for modeling and forecasting space weather conditions near Earth.

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Multiple, distant (40°) in situ observations of a magnetic cloud and a corotating interaction region complex

Cited by 64 publications

References 73 publications

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

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

Global axis shape of magnetic clouds deduced from the distribution of their local axis orientation

Quantitative model for the generic 3D shape of ICMEs at 1 AU

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