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

Démoulin, P.; Janvier, Miho; Masías-Meza, J. J.; Dasso, S.

doi:10.1051/0004-6361/201628164

Cited by 17 publications

(15 citation statements)

References 77 publications

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“…As we saw earlier, attempts to take into account the curvature at the CME front (as deduced by 3D reconstructions) are not always successful in improving ToA and/or SoA [10,20]. Theoretical models, based on compilations of extensive sets of in situ observations, relating CME/shock shapes at 1 AU with coronal properties such as their width exist [50], and should be compared with actual observations. A recent evaluation of different shapes in the MHD modelling of a single (and rather simple) event demonstrated the importance of that parameter for SWx forecasting [51].…”

Section: (G) Hit/missmentioning

confidence: 99%

Predicting the geoeffective properties of coronal mass ejections: current status, open issues and path forward

Vourlidas

Patsourakos

Savani

2019

Phil. Trans. R. Soc. A.

109

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Much progress has been made in the study of coronal mass ejections (CMEs), the main drivers of terrestrial space weather thanks to the deployment of several missions in the last decade. The flow of energy required to power solar eruptions is beginning to be understood. The initiation of CMEs is routinely observed with cadences of tens of seconds with arc-second resolution. Their inner heliospheric evolution can now be imaged and followed routinely. Yet relatively little progress has been made in predicting the geoeffectiveness of a particular CME. Why is that? What are the issues holding back progress in medium-term forecasting of space weather? To answer these questions, we review, here, the measurements, status and open issues on the main CME geoeffective parameters; namely, their entrained magnetic field strength and configuration, their Earth arrival time and speed, and their mass (momentum). We offer strategies for improving the accuracy of the measurements and their forecasting in the near and mid-term future. To spark further discussion, we incorporate our suggestions into a top-level draft action plan that includes suggestions for sensor deployment, technology development and modelling/theory improvements. This article is part of the theme issue ‘Solar eruptions and their space weather impact’.

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Section: (G) Hit/missmentioning

confidence: 99%

Predicting the geoeffective properties of coronal mass ejections: current status, open issues and path forward

Vourlidas

Patsourakos

Savani

2019

Phil. Trans. R. Soc. A.

109

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“…Then, using statistical tools on these catalogs allows investigating generic features of ICMEs in details. In recent papers, Janvier et al (2014Janvier et al ( , 2015 and Démoulin et al (2016) investigated the generic shape of the MC axis as well as that of the shock at the forefront of ICMEs, by using lists of reported orientations of MC axis Another technique is the so-called superposed epoch analysis (SEA or Chree analysis, Chree, 1914), which allows one to superpose time series of parameters within well-delimited structures (at least, bounded by one clear frontier such as a discontinuity). This technique has been used in a variety of cases, in particular in the SW for the investigation of corotating interaction regions (Yermolaev et al, 2015), ICMEs (Janvier et al, 2019), and MCs (Masías-Meza et al, 2016;Rodriguez et al, 2016).…”

Section: 1029/2020ja028150mentioning

confidence: 99%

Section: Research Articlementioning

confidence: 99%

20 Years of ACE Data: How Superposed Epoch Analyses Reveal Generic Features in Interplanetary CME Profiles

et al. 2020

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Interplanetary coronal mass ejections (ICMEs) are magnetic structures propagating from the Sun's corona to the interplanetary medium. With over 20 years of observations at the L1 libration point, ACE offers hundreds of ICMEs detected at different times during several solar cycles and with different features such as the propagation speed. We investigate a revisited catalog of more than 400 ICMEs using the superposed epoch method on the mean, median, and the most probable values of the distribution of magnetic and plasma parameters. We also investigate the effects of the speed of ICMEs relative to the solar wind, the solar cycle, and the existence of a magnetic cloud on the generic ICME profile. We find that fast-propagating ICMEs (relatively to the solar wind in front) still show signs of compression at 1 au, as seen by the compressed sheath and the asymmetric profile of the magnetic field. While the solar cycle evolution does not impact the generic features of ICMEs, there are more extreme events during the active part of the cycle, widening the distributions of all parameters. Finally, we find that ICMEs with or without a detected magnetic cloud show similar profiles, which confirms the hypothesis that ICMEs with no detected magnetic clouds are crossed further away from the flux rope core. Such a study provides a generic understanding of processes that shape the overall features of ICMEs in the solar wind and can be extended with future missions at different locations in the solar system. Plain Language Summary Interplanetary coronal mass ejections (ICMEs) are magnetized clouds of solar material expelled from the Sun's atmosphere into the interplanetary medium. In the present article, we use plasma and magnetic data from the NASA ACE mission positioned at the Lagrange 1 point and perform statistical studies over the 400 ICMEs detected over the last 20 years. Such an approach, called a superposed epoch analysis, provides a temporal description of the generic features of ICMEs. In particular, we find that ICMEs that propagate faster than their surrounding solar wind still show compressed regions of plasmas and stronger magnetic field. While we find that the 11-year solar cycle does not affect the generic properties of ICMEs, we observe more extreme events during the active phase. Finally, we also find that a subset of ICMEs, called magnetic clouds and often associated with a stronger and more coherent magnetic field, have the same properties as other ICMEs. This confirms that most ICMEs may be magnetic clouds but which detection is limited by the spacecraft crossing. Such a study, based on long-term heliospheric missions, allows us to probe physical processes that occur during the propagation of ICMEs, which can help better predict space weather and its consequences.

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“…FRs store and transport magnetic energy and helicity (H) (e.g. Gosling 1990;Dasso 2009;Nakwacki et al 2011;Démoulin et al 2016a;Kilpua et al 2017), and the distribution of twist is one major key for determining H. Moreover, the twist distribution has consequences on the propagation of energetic particles inside MCs, in particular because the amount of twist modifies the field line length. Larson et al (1997) determined the length of the field lines in an MC as a function of the FR radius from both solar and in situ observations by tracking energetic particles.…”

Section: Introductionmentioning

confidence: 99%

Magnetic twist profile inside magnetic clouds derived with a superposed epoch analysis

Lanabere

Masías-Meza

Rodriguez

et al. 2020

A&A

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Context. Magnetic clouds (MCs) are large-scale interplanetary transient structures in the heliosphere that travel from the Sun into the interplanetary medium. The internal magnetic field lines inside the MCs are twisted, forming a flux rope (FR). This magnetic field structuring is determined by its initial solar configuration, by the processes involved during its eruption from the Sun, and by the dynamical evolution during its interaction with the ambient solar wind. Aims. One of the most important properties of the magnetic structure inside MCs is the twist of the field lines forming the FR (the number of turns per unit length). The detailed internal distribution of twist is under debate mainly because the magnetic field (B) in MCs is observed only along the spacecraft trajectory, and thus it is necessary to complete observations with theoretical assumptions. Estimating the twist from the study of a single event is difficult because the field fluctuations significantly increase the noise of the observed B time series and thus the bias of the deduced twist. Methods. The superposed epoch applied to MCs has proven to be a powerful technique, permitting the extraction of their common features, and removing the peculiarity of individual cases. We apply a superposed epoch technique to analyse the magnetic components in the local FR frame of a significant sample of moderately asymmetric MCs observed at 1 au. Results. From the superposed profile of B components in the FR frame, we determine the typical twist distribution in MCs. The twist is nearly uniform in the FR core (central half part), and it increases moderately, up to a factor two, towards the MC boundaries. This profile is close to the Lundquist field model limited to the FR core where the axial field component is above about one-third of its central value.

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

Cited by 17 publications

References 77 publications

Predicting the geoeffective properties of coronal mass ejections: current status, open issues and path forward

Predicting the geoeffective properties of coronal mass ejections: current status, open issues and path forward

20 Years of ACE Data: How Superposed Epoch Analyses Reveal Generic Features in Interplanetary CME Profiles

Magnetic twist profile inside magnetic clouds derived with a superposed epoch analysis

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