Impact of the solar activity on the propagation of ICMEs: Simulations of hydro, magnetic and median ICMEs at minimum and maximum of activity

The propagation of Interplanetary Coronal Mass Ejections (ICMEs) in the heliosphere is influenced by many physical phenomena, related to the internal structure of the ICME and its interaction with the ambient solar wind and magnetic field. As the solar magnetic field is modulated by the 11-year dynamo cycle, our goal is to perform a theoretical exploratory study to assess the difference of propagation of an ICME in typical minimum and maximum activity backgrounds. We define a median representative CME at 0.1~au, using both observations and numerical simulations, and describe it using a spheromak model. We use the heliospheric propagator European Heliospheric FORecasting Information Asset (EUHFORIA) to inject the same ICME in two different background wind environments. We then study how the environment and the internal CME structure impact the propagation of the ICME towards Earth, by comparison with an unmagnetized CME. At minimum of activity, the structure of the heliosphere around the ecliptic causes the ICME to slow down, creating a delay with the polar parts of the ejecta. This delay is more important if the ICME is faster. At maximum of activity, a southern coronal hole causes a northward deflection. For these cases, we always find that the ICME at maximum of activity arrives first, while the ICME at minimum of activity is actually more geo-effective. The helicity sign of the ICME is also a crucial parameter but at minimum of activity only, since it affects the magnetic profile and the arrival time of up to 8 hours.Comment: 25 pages, 16 figures, accepted in Ap

The Width of Magnetic Ejecta Measured Near 1 au: Lessons from STEREO-A Measurements in 2021--2022

Coronal mass ejections (CMEs) are large-scale eruptions with a typical radial size at 1 au of 0.21 au but their angular width in interplanetary space is still mostly unknown, especially for the magnetic ejecta (ME) part of the CME. We take advantage of STEREO-A angular separation of 20$^\circ$-60$^\circ$ from the Sun-Earth line from October 2020 to August 2022, and perform a two-part study to constrain the angular width of MEs in the ecliptic plane: a) we study all CMEs that are observed remotely to propagate between the Sun-STEREO-A and the Sun-Earth lines and determine how many impact one or both spacecraft in situ, and b) we investigate all in situ measurements at STEREO-A or at L1 of CMEs during the same time period to quantify how many are measured by the two spacecraft. A key finding is that, out of 21 CMEs propagating within 30$^\circ$ of either spacecraft, only four impacted both spacecraft and none provided clean magnetic cloud-like signatures at both spacecraft. Combining the two approaches, we conclude that the typical angular width of a ME at 1 au is $\sim$ 20$^\circ$-30$^\circ$, or 2-3 times less than often assumed and consistent with a 2:1 elliptical cross-section of an ellipsoidal ME. We discuss the consequences of this finding for future multi-spacecraft mission designs and for the coherence of CMEs.Comment: 21 pages, revision submitted to Ap

New Observations Needed to Advance Our Understanding of Coronal Mass Ejections

Coronal mass ejections (CMEs) are large eruptions from the Sun that propagate through the heliosphere after launch. Observational studies of these transient phenomena are usually based on 2D images of the Sun, corona, and heliosphere (remote-sensing data), as well as magnetic field, plasma, and particle samples along a 1D spacecraft trajectory (in-situ data). Given the large scales involved and the 3D nature of CMEs, such measurements are generally insufficient to build a comprehensive picture, especially in terms of local variations and overall geometry of the whole structure. This White Paper aims to address this issue by identifying the data sets and observational priorities that are needed to effectively advance our current understanding of the structure and evolution of CMEs, in both the remote-sensing and in-situ regimes. It also provides an outlook of possible missions and instruments that may yield significant improvements into the subject.Comment: White Paper submitted to the Heliophysics 2024-2033 Decadal Survey, 9 pages, 4 figure

Redefining flux ropes in heliophysics

Magnetic flux ropes manifest as twisted bundles of magnetic field lines. They carry significant amounts of solar mass in the heliosphere. This paper underlines the need to advance our understanding of the fundamental physics of heliospheric flux ropes and provides the motivation to significantly improve the status quo of flux rope research through novel and requisite approaches. It briefly discusses the current understanding of flux rope formation and evolution, and summarizes the strategies that have been undertaken to understand the dynamics of heliospheric structures. The challenges and recommendations put forward to address them are expected to broaden the in-depth knowledge of our nearest star, its dynamics, and its role in its region of influence, the heliosphere.Fil: Nieves Chinchilla, Teresa. National Aeronautics and Space Administration; Estados UnidosFil: Pal, Sanchita. George Mason University. School Of Physics. Astronomy And Computational Sciences; Estados Unidos. National Aeronautics and Space Administration; Estados UnidosFil: Salman, Tarik M.. George Mason University. School Of Physics. Astronomy And Computational Sciences; Estados Unidos. National Aeronautics and Space Administration; Estados UnidosFil: Carcaboso, Fernando. Catholic University Of America; Estados Unidos. National Aeronautics and Space Administration; Estados UnidosFil: Guidoni, Silvina E.. American University. College Of Arts & Sciences. Physics Departament.; Estados Unidos. National Aeronautics and Space Administration; Estados UnidosFil: Cremades Fernandez, Maria Hebe. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Mendoza. Facultad de Ingenieria; ArgentinaFil: Narock, Ayris. National Aeronautics and Space Administration; Estados UnidosFil: Balmaceda, Laura Antonia. George Mason University. School Of Physics. Astronomy And Computational Sciences; Estados Unidos. National Aeronautics and Space Administration; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lynch, Benjamin J.. University of California at Berkeley; Estados UnidosFil: Al Haddad, Nada. University Of New Hampshire; Estados UnidosFil: Rodríguez García, Laura. Universidad de Alcalá; EspañaFil: Narock, Thomas W.. Goucher College; Estados UnidosFil: Dos Santos, Luiz F. G.. Shell Global Solutions; Estados UnidosFil: Regnault, Florian. University Of New Hampshire; Estados UnidosFil: Kay, Christina. Catholic University Of America; Estados Unidos. National Aeronautics and Space Administration; Estados UnidosFil: Winslow, Réka M.. University Of New Hampshire; Estados UnidosFil: Palmerio, Erika. Predictive Science Inc.; Estados UnidosFil: Davies, Emma E.. University Of New Hampshire; Estados UnidosFil: Scolini, Camilla. University Of New Hampshire; Estados UnidosFil: Weiss, Andreas J.. National Aeronautics and Space Administration; Estados UnidosFil: Alzate, Nathalia. National Aeronautics and Space Administration; Estados UnidosFil: Jeunon, Mariana. Catholic University Of America; Estados Unidos. National Aeronautics and Space Administration; Estados UnidosFil: Pujadas, Roger. Universidad Politécnica de Catalunya; España. National Aeronautics and Space Administration; Estados Unido

On the importance of investigating CME complexity evolution during interplanetary propagation

This perspective paper brings to light the need for comprehensive studies on the evolution of interplanetary coronal mass ejection (ICME) complexity during propagation. To date, few studies of ICME complexity exist. Here, we define ICME complexity and associated changes in complexity, describe recent works and their limitations, and outline key science questions that need to be tackled. Fundamental research on ICME complexity changes from the solar corona to 1 AU and beyond is critical to our physical understanding of the evolution and interaction of transients in the inner heliosphere. Furthermore, a comprehensive understanding of such changes is required to understand the space weather impact of ICMEs at different heliospheric locations and to improve on predictive space weather models

Origin and evolution of coronal mass ejections in the heliosphere

Les éjections coronales de masse interplanétaires (ICMEs, pour Interplanetary Coronal Mass Ejections en anglais) proviennent de l'éruption de structures magnétiques complexes dans l'atmosphère de notre étoile. Elles se propagent dans le milieu interplanétaire, où elles peuvent être analysées par des sondes spatiales. Les ICMEs sont connues pour générer des tempêtes géomagnétiques capables de perturber nos technologies sur Terre, c'est pour cela qu'elles constituent une source d'intérêt. L'étude des ICMEs pourrait donc nous permettre de prévoir et de réduire leur impact sur notre technologie. Lorsqu'elles sont assez rapides, les ICMEs peuvent accumuler suffisamment de plasma de vent solaire pour former une gaine turbulente devant elles. Elles sont donc constituées de deux sous-structures principales : une gaine et un éjecta magnétique (ME). L'éjecta magnétique est la partie principale d'une ICME où le champ magnétique est plus intense et plus régulier que celui du soleil ambiant. L'objectif de cette thèse est d'étudier les mécanismes physiques qui se produisent pendant la propagation d'une ICME dans le système solaire. Pour ce faire, nous effectuons d'abord une étude statistique, que l'on appelle la méthode des époques superposées, sur un catalogue de plus de 300 ICMEs où nous considérons les profils des paramètres physiques (tels que l'intensité du champ magnétique, la vitesse, la température, etc) des ICMEs vus à 1 au par la sonde spatiale ACE. En particulier, nous étudions différentes classifications possibles des ICMEs, par exemple en fonction de leur vitesse, de la phase du cycle solaire où elles sont détectées, et de la détection d'un nuage magnétique ou non (MC). Il s'agît d'un sous-ensemble des MEs avec une rotation claire du champ magnétique ainsi qu'une faible température du plasma par rapport au vent solaire. Nous montrons que les ICMEs ne sont pas distribuées en groupes distincts, mais plutôt dans un continuum dans leur espace de paramètres. Nous confirmons que les ICMEs lentes ont un profil plus symétrique que les ICMEs rapides, généralisant ainsi le travail effectué sur un échantillon de 44 ICMEs avec des nuages magnétiques clairement identifiés par Masias-Meza et al. 2016. Nous constatons également que les ICMEs rapides montrent des signes de compression à la fois dans leur éjecta magnétique et dans leur gaine. Parallèlement à cette étude, nous présentons également les résultats de la simulation de la propagation d'un ensemble de tubes de flux Titov-Démoulin (Titov et al. 2014) avec différents champs magnétiques et tailles au sein d'un vent solaire idéalisé. Ceci est réalisé avec le module MHD 3D du code PLUTO sur une grille AMR. Notre grille commence dans la basse couronne et va jusqu'à 2 unités astronomiques. Cela nous permet d'étudier l'effet de l'intensité du champ magnétique ou de la taille d'un tube de flux à l'initiation sur ses propriétés durant la propagation. Ceci met alors en évidence les processus physiques qui se produisent pendant la propagation. Nous constatons que les tubes de flux plus minces tournent différemment des tubes de flux plus épais durant les premières phases de propagation. L'évolution du champ magnétique du tube de flux au cours de sa propagation est en accord avec les lois d'évolution déduites des observations. Nous simulons ensuite les profils que les sondes spatiales auraient mesurés au niveau de Mercure et de la Terre dans nos simulations et nous comparons avec les résultats de Janvier et al. 2019 et Regnault et al. 2020. Les composantes magnétiques des tubes de flux simulés correspondent bien à ce que nous attendons de la théorie (Lundquist et al. 1950). Cette thèse présente ainsi les bases pour modéliser de manière auto-cohérente en 3D l'éruption et la propagation des ICMEs depuis la basse couronne jusqu'à l'orbite de la Terre.Interplanetary Coronal Mass Ejections (ICMEs) originate from the eruption of complex magnetic structures occurring in our star's atmosphere. They propagate in the interplanetary medium, where they can be probed by spacecraft. ICMEs are known to generate geomagnetic storms that can disturb our technologies on earth, this is why they are a subject of interest.Studying ICMEs could, therefore, allow us to predict and lower their impact in our technology. When they are fast enough, ICMEs can accumulate enough solar wind plasma to form a turbulent sheath ahead of them. They therefore consist of two main substructures : a sheath and a magnetic ejecta (ME). The magnetic ejecta is the main body of an ICME where the magnetic field is more intense and with less variance than that of the ambient solar wind. The aim of this PhD is to study the physical mechanisms that happen during the propagation of an ICME. To do so, we first run a statistical study using the superposed epoch analysis technique on a catalogue of more than 300 ICMEs where we consider the profiles of the physical parameters (like the magnetic field intensity, the speed, temperature, etc) of the ICMEs seen at 1~au by the ACE spacecraft. In particular, we investigate different possible classifications of ICMEs, for example based on their speeds, the phase of the solar cycle when they are detected, and the detection of an associated magnetic cloud (MC) or not. MCs are a subset of MEs with a clear rotation of the magnetic field as well as a low plasma temperature compared with the solar wind. We show that ICMEs are not distributed in distinct clusters but rather in a continuum in their parameter space. We confirm that slow ICMEs have a more symmetric profile than fast ICMEs, therefore generalizing the work made on a sample of 44 ICMEs with clearly identified magnetic clouds by Masias-Meza et al. 2016. We also find that fast ICMEs show signs of compression in both their magnetic ejecta and in their sheath. In parallel, we also present the simulation results of the propagation of a set of Titov-Démoulin flux ropes (Titov et al. 2014) with different magnetic fields and sizes within an idealized solar wind. This is done with the 3D MHD module of the PLUTO code on an AMR grid. Our grid starts in the low corona and goes up to 2 astronomical units. This allows us to study the effect of the magnetic field intensity or of the size of the flux rope at the initiation on its properties during the propagation, highlighting the physical processes happening during the propagation. We find that thinner flux ropes rotate differently than thicker ones in the initial phase of the propagation. The evolution of the magnetic field of the flux rope during the propagation agrees with evolution laws deduced from observations. We then simulate in situ profiles that spacecrafts would have measured at Mercury and at the Earth, and we compare with the results of Janvier et al. 2019 and Regnault et al. 2020. The magnetic components of the simulated flux rope match well with what we are expecting from theory (Lundquist et al. 1950). This thesis therefore presents the grounds for modelling self-consistently in 3D the eruption and propagation of ICMEs from the low corona up to the orbit of the Earth

Origine et évolution des éjections coronales de masse dans l'héliosphère

Interplanetary Coronal Mass Ejections (ICMEs) originate from the eruption of complex magnetic structures occurring in our star's atmosphere. They propagate in the interplanetary medium, where they can be probed by spacecraft. ICMEs are known to generate geomagnetic storms that can disturb our technologies on earth, this is why they are a subject of interest.Studying ICMEs could, therefore, allow us to predict and lower their impact in our technology. When they are fast enough, ICMEs can accumulate enough solar wind plasma to form a turbulent sheath ahead of them. They therefore consist of two main substructures : a sheath and a magnetic ejecta (ME). The magnetic ejecta is the main body of an ICME where the magnetic field is more intense and with less variance than that of the ambient solar wind. The aim of this PhD is to study the physical mechanisms that happen during the propagation of an ICME. To do so, we first run a statistical study using the superposed epoch analysis technique on a catalogue of more than 300 ICMEs where we consider the profiles of the physical parameters (like the magnetic field intensity, the speed, temperature, etc) of the ICMEs seen at 1~au by the ACE spacecraft. In particular, we investigate different possible classifications of ICMEs, for example based on their speeds, the phase of the solar cycle when they are detected, and the detection of an associated magnetic cloud (MC) or not. MCs are a subset of MEs with a clear rotation of the magnetic field as well as a low plasma temperature compared with the solar wind. We show that ICMEs are not distributed in distinct clusters but rather in a continuum in their parameter space. We confirm that slow ICMEs have a more symmetric profile than fast ICMEs, therefore generalizing the work made on a sample of 44 ICMEs with clearly identified magnetic clouds by Masias-Meza et al. 2016. We also find that fast ICMEs show signs of compression in both their magnetic ejecta and in their sheath. In parallel, we also present the simulation results of the propagation of a set of Titov-Démoulin flux ropes (Titov et al. 2014) with different magnetic fields and sizes within an idealized solar wind. This is done with the 3D MHD module of the PLUTO code on an AMR grid. Our grid starts in the low corona and goes up to 2 astronomical units. This allows us to study the effect of the magnetic field intensity or of the size of the flux rope at the initiation on its properties during the propagation, highlighting the physical processes happening during the propagation. We find that thinner flux ropes rotate differently than thicker ones in the initial phase of the propagation. The evolution of the magnetic field of the flux rope during the propagation agrees with evolution laws deduced from observations. We then simulate in situ profiles that spacecrafts would have measured at Mercury and at the Earth, and we compare with the results of Janvier et al. 2019 and Regnault et al. 2020. The magnetic components of the simulated flux rope match well with what we are expecting from theory (Lundquist et al. 1950). This thesis therefore presents the grounds for modelling self-consistently in 3D the eruption and propagation of ICMEs from the low corona up to the orbit of the Earth.Les éjections coronales de masse interplanétaires (ICMEs, pour Interplanetary Coronal Mass Ejections en anglais) proviennent de l'éruption de structures magnétiques complexes dans l'atmosphère de notre étoile. Elles se propagent dans le milieu interplanétaire, où elles peuvent être analysées par des sondes spatiales. Les ICMEs sont connues pour générer des tempêtes géomagnétiques capables de perturber nos technologies sur Terre, c'est pour cela qu'elles constituent une source d'intérêt. L'étude des ICMEs pourrait donc nous permettre de prévoir et de réduire leur impact sur notre technologie. Lorsqu'elles sont assez rapides, les ICMEs peuvent accumuler suffisamment de plasma de vent solaire pour former une gaine turbulente devant elles. Elles sont donc constituées de deux sous-structures principales : une gaine et un éjecta magnétique (ME). L'éjecta magnétique est la partie principale d'une ICME où le champ magnétique est plus intense et plus régulier que celui du soleil ambiant. L'objectif de cette thèse est d'étudier les mécanismes physiques qui se produisent pendant la propagation d'une ICME dans le système solaire. Pour ce faire, nous effectuons d'abord une étude statistique, que l'on appelle la méthode des époques superposées, sur un catalogue de plus de 300 ICMEs où nous considérons les profils des paramètres physiques (tels que l'intensité du champ magnétique, la vitesse, la température, etc) des ICMEs vus à 1 au par la sonde spatiale ACE. En particulier, nous étudions différentes classifications possibles des ICMEs, par exemple en fonction de leur vitesse, de la phase du cycle solaire où elles sont détectées, et de la détection d'un nuage magnétique ou non (MC). Il s'agît d'un sous-ensemble des MEs avec une rotation claire du champ magnétique ainsi qu'une faible température du plasma par rapport au vent solaire. Nous montrons que les ICMEs ne sont pas distribuées en groupes distincts, mais plutôt dans un continuum dans leur espace de paramètres. Nous confirmons que les ICMEs lentes ont un profil plus symétrique que les ICMEs rapides, généralisant ainsi le travail effectué sur un échantillon de 44 ICMEs avec des nuages magnétiques clairement identifiés par Masias-Meza et al. 2016. Nous constatons également que les ICMEs rapides montrent des signes de compression à la fois dans leur éjecta magnétique et dans leur gaine. Parallèlement à cette étude, nous présentons également les résultats de la simulation de la propagation d'un ensemble de tubes de flux Titov-Démoulin (Titov et al. 2014) avec différents champs magnétiques et tailles au sein d'un vent solaire idéalisé. Ceci est réalisé avec le module MHD 3D du code PLUTO sur une grille AMR. Notre grille commence dans la basse couronne et va jusqu'à 2 unités astronomiques. Cela nous permet d'étudier l'effet de l'intensité du champ magnétique ou de la taille d'un tube de flux à l'initiation sur ses propriétés durant la propagation. Ceci met alors en évidence les processus physiques qui se produisent pendant la propagation. Nous constatons que les tubes de flux plus minces tournent différemment des tubes de flux plus épais durant les premières phases de propagation. L'évolution du champ magnétique du tube de flux au cours de sa propagation est en accord avec les lois d'évolution déduites des observations. Nous simulons ensuite les profils que les sondes spatiales auraient mesurés au niveau de Mercure et de la Terre dans nos simulations et nous comparons avec les résultats de Janvier et al. 2019 et Regnault et al. 2020. Les composantes magnétiques des tubes de flux simulés correspondent bien à ce que nous attendons de la théorie (Lundquist et al. 1950). Cette thèse présente ainsi les bases pour modéliser de manière auto-cohérente en 3D l'éruption et la propagation des ICMEs depuis la basse couronne jusqu'à l'orbite de la Terre

Impact of the Solar Activity on the Propagation of ICMEs: Simulations of Hydro, Magnetic and Median ICMEs at the Minimum and Maximum of Activity

International audienceAbstract The propagation of interplanetary coronal mass ejections (ICMEs) in the heliosphere is influenced by many physical phenomena, related to the internal structure of the ICME and its interaction with the ambient solar wind and magnetic field. As the solar magnetic field is modulated by the 11 yr dynamo cycle, our goal is to perform a theoretical exploratory study to assess the difference of propagation of an ICME in typical minimum and maximum activity backgrounds. We define a median representative CME at 0.1 au, using both observations and numerical simulations, and describe it using a spheromak model. We use the heliospheric propagator EUropean Heliospheric FORecasting Information Asset to inject the same ICME in two different background wind environments. We then study how the environment and the internal CME structure impact the propagation of the ICME toward Earth, by comparison with an unmagnetized CME. At minimum of activity, the structure of the heliosphere around the ecliptic causes the ICME to slow down, creating a delay with the polar parts of the ejecta. This delay is more important if the ICME is faster. At maximum of activity, a southern coronal hole causes a northward deflection. For these cases, we always find that the ICME at the maximum of activity arrives first, while the ICME at the minimum of activity is actually more geoeffective. The sign of the helicity of the ICME is also a crucial parameter, but at the minimum of activity only, since it affects the magnetic profile and the arrival time up to 8 hr

The Two-step Forbush Decrease: A Tale of Two Substructures Modulating Galactic Cosmic Rays within Coronal Mass Ejections

International audienceInterplanetary coronal mass ejections (ICMEs) are known to modify the structure of the solar wind as well as interact with the space environment of planetary systems. Their large magnetic structures have been shown to interact with galactic cosmic rays (GCRs), leading to the Forbush decrease (FD) phenomenon. We revisit in the present article the 17 yr of Advanced Composition Explorer spacecraft ICME detection along with two neutron monitors (McMurdo and Oulu) with a superposed epoch analysis to further analyze the role of the magnetic ejecta in driving FDs. We investigate in the following the role of the sheath and the magnetic ejecta in driving FDs, and we further show that for ICMEs without a sheath, a magnetic ejecta only is able to drive significant FDs of comparable intensities. Furthermore, a comparison of samples with and without a sheath with similar speed profiles enable us to show that the magnetic field intensity, rather than its fluctuations, is the main driver for the FD. Finally, the recovery phase of the FD for isolated magnetic ejecta shows an anisotropy in the level of the GCRs. We relate this finding at 1 au to the gradient of the GCR flux found at different heliospheric distances from several interplanetary missions

Pétropolitiques aux Suds

En considérant le pétrole comme un fait social total, ce dossier thématique étudie ce que le pétrole fait aux pays pétroliers des Suds, en Afrique et Amérique latine, selon trois axes de réflexion : la soutenabilité des modèles politiques, économiques et sociaux des pays producteurs et exportateurs, les savoirs spécifiques développés dans et par ces pays, et la transformation des territoires, luttes sociales et politiques qui découlent de la dépendance économique à une énergie fossile. This thematic dossier considers oil as a total societal fact and focuses on what oil is doing to oil-producing countries in the South, in Africa and Latin America, following three lines of analysis: the sustainability of the political, economic and social models of the producing and exporting countries, the specific knowledge and skills developed in and by these countries, and the transformation of the geographical contexts, social and political issues that result from economic dependency on fossil energy. Considerando el petróleo como un hecho social total, este dossier temático estudia los impactos del petróleo en los países petroleros del Sur, en África y en América Latina partiendo de tres líneas de reflexión: la sostenibilidad de los modelos políticos, económicos y sociales de los países productores y exportadores, los conocimientos específicos desarrollados en y por estos países, y la transformación de los territorios, luchas sociales y políticas resultantes de la dependencia económica a una energía fósil