Coronal mass ejections (CMEs) are large-scale eruptions of magnetized plasma from the Sun's lower atmosphere, significantly influencing space weather and planetary environments. To improve predictions of CME arrival and their impacts on Earth and its surroundings, a deeper understanding of their origins, initiation, and complex early evolution is crucial. While coronagraphic observations have been essential for studying the dynamics of CMEs, they cannot capture the initial, critical phase of CME development. Consequently, investigating indirect phenomena in the lower solar atmosphere has become essential. One of the most prominent indirect indicators associated with CMEs is coronal dimming. These are localized, sudden decreases in coronal emission observed at extreme ultraviolet and soft X-ray wavelengths, which evolve rapidly during the lift-off and early expansion phases of CMEs. Coronal dimmings have been interpreted both as “footprints” of the erupting magnetic structure and as indicators of coronal mass loss in the lower corona.
I will review recent advancements in using coronal dimmings to diagnose CMEs. Topics covered will include statistical studies linking dimming characteristics to CME mass and speed, the use of dimmings as early indicators of CME propagation direction, and insights into the magnetic topology and reconfiguration of the early CME stages based on dimming locations and fine structure. Additionally, the potential role of dimmings in the pre-event phase preceding CME onset will be discussed. Finally, I will highlight future research directions and underexplored areas in CME science, emphasizing the untapped potential of coronal dimmings in advancing our understanding of these dynamic solar events.
How to cite: Dissauer, K.: Footprints of Giants – Exploring Early Diagnostics of Coronal Mass Ejections Through Coronal Dimmings, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17289, https://doi.org/10.5194/egusphere-egu25-17289, 2025.
Understanding mesoscale structures in the solar wind background and coronal mass ejections (CMEs) is one of the science objectives of the PUNCH mission to be launched in early 2025. We do not fully understand what processes form these structures and where as well as how they evolve from the outer solar corona through the heliosphere. In anticipation of the detailed high-sensitive large field-of-view PUNCH imaging, MHD simulations capable of modeling the global inner heliosphere while simultaneously resolving structures at mesoscales can help predict what structures we can expect to form in certain CME-solar wind interaction scenarios. We use an efficiently parallelized and scalable physics-based MHD model with numerical algorithms featuring high resolving power to perform global inner heliosphere simulations with CMEs with a high resolution. Using the GAMERA-Helio inner heliosphere model coupled with the Gibson-Low CME model, we model the evolution of a wide and fast CME flux rope through a realistic solar wind background. The simulation resolves spatial scales down to ~0.1 solar radii (~10 Earth radii), enabling, to study mesoscale structures that form in the CME-solar wind interaction in a global context. We discuss the development of ripples and irregularities at the CME shock, compressions, and magnetic field fluctuations in the CME-driven sheath, and connect these structures with the interaction between the CME and background solar wind flows. By computing the total and polarized white light brightness from high-resolution GAMERA MHD simulations, we show how mesoscale structures that form at the CME-solar wind interface appear in synthetic images in the FOV of the PUNCH mission.
How to cite: Provornikova, E., Merkin, V., Samara, E., Braga, C., Malanushenko, A., McCubbin, A., and Gibson, S.: High-Resolution Simulations of CME-Solar Wind Interaction in The Heliosphere: A Focus On Mesoscale Structures For PUNCH, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14092, https://doi.org/10.5194/egusphere-egu25-14092, 2025.
Coronagraphic observations enable the monitoring of coronal mass ejections (CMEs) through scattered light from free electrons. These observations allow for the estimation of the density, velocity, and propagation direction of the ejected plasma, which is critical for space weather forecasting. However, determining the 3D plasma distribution from 2D imaging data is challenging due to the optically thin medium and the complex image formation processes based on scattered light.
We present a method for 3D tomographic reconstructions of the heliosphere using multi-viewpoint coronagraphic observations. Our method leverages Neural Radiance Fields (NeRFs) to estimate the electron density in the heliosphere through a ray-tracing approach. The model is optimized by iteratively fitting the time-dependent observational data, accounting for the underlying Thomson scattering of image formation. Typically, tomographic reconstructions based on a limited number of viewpoints are insufficient to constrain the 3D plasma distribution. To address this, we introduce additional physical constraints, including continuity, solar wind speed, and propagation direction, to enable a physics-informed tomographic reconstruction.
We utilize synthetic observations of CMEs based on GAMERA simulations to evaluate the model's performance with respect to viewpoint positions, physics-based constraints, and CME configurations. The results demonstrate that our method can reliably estimate the CME propagation direction and velocity using two viewpoints. Furthermore, we show that additional viewpoints can be seamlessly integrated, enhancing the reconstruction of the plasma distribution in the heliosphere and improving CME forecasting capabilities. This research underscores the value of physics-informed methods for 3D CME tomography, paving the way for advanced space weather monitoring.
How to cite: Jarolim, R., Hung, C.-M., Lamdouar, H., Sanner, M., Stevenson, E., Veitch-Michaelis, J., Bouri, I., Malanushenko, A., Ruzicka, V., and Urbina-Ortega, C.: Tomographic Reconstructions of Coronal Mass Ejections with Physics-Informed Neural Radiance Fields, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13105, https://doi.org/10.5194/egusphere-egu25-13105, 2025.
Data-driven simulations of the solar corona have gathered traction in recent years for modelling the destabilisation of magnetic flux ropes (MFRs). To correctly apply and interpret results from these modelling efforts, it is crucial to understand how MFRs behave in such simulations and why they exhibit certain behaviour. For example, one aspect is to understand what effect does the evolution of the photospheric magnetic field have on the MFR system once it has reached an already unstable state. To probe the effect of data-driving, we first run a fully data-driven time-dependent magnetofrictional (TMF) simulation. Subsequently, we systematically relax the model (i.e., turn off the photospheric driving) at different times and analyse the MFRs' behaviour. In addition to the magnetofrictional relaxation, we also employ a zero-beta magnetohydrodynamics (MHD) model for the relaxation part of the analysis and compare the differences. To extract the simulated MFRs we use our novel Graphical User Interface for Tracking and Analysing flux Ropes (GUITAR). We find that even for MFRs that have been found to be eruptive in the relaxation simulations, MFR properties can greatly vary depending on the time of relaxation. Furthermore, there are striking differences between magnetofrictional and MHD relaxation simulations; not all initial TMF states which are eruptive in MHD are eruptive in the magnetofrictional relaxation. Furthermore, not only do the MFR properties significantly vary, but also the interpretation of which instability is at play varies between the two modelling prescriptions.
How to cite: Wagner, A., Price, D. J., Bourgeois, S., Daei, F., Pomoell, J., Poedts, S., Kumari, A., Barata, T., Erdélyi, R., and Kilpua, E. K. J.: Magnetic flux rope evolution and stability in data-driven coronal magnetic field simulations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1591, https://doi.org/10.5194/egusphere-egu25-1591, 2025.
Interplanetary coronal mass ejections often carry large-scale magnetic clouds, which display internal substructures and small-scale fluctuations. These complex multi-scale clouds represent the main drivers of geomagnetic storms at Earth, and the amplitude, coherence and variability of their magnetic field all contribute to their geoeffectivity.
We present high resolution simulations of a magnetic cloud interacting with turbulent fluctuations while propagating in the spherically expanding solar wind; we investigate the effects of turbulence on the internal dynamics and magnetic field variability. Our simulations employ the expanding box model, a semi-lagrangian numerical approach that allows to follow the evolution of a parcel of plasma in the spherical solar wind flow, decoupling the small-scale internal dynamics from the large-scale motion.
We recover observed features such as the radial expansion of the structure and the low-temperature and low-beta signatures of magnetic clouds, together with a quite rich internal dynamics. We also find that turbulent reconnection and field transport produce smaller secondary magnetic flux ropes, possibly enhancing the cloud's geoeffectivity; this behaviour might also account for the relatively small magnetic correlation lengths which have been estimated in interplanetary magnetic clouds.
How to cite: Sangalli, M., Verdini, A., Landi, S., and Papini, E.: The turbulent evolution of an interplanetary magnetic cloud in the expanding solar wind, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4434, https://doi.org/10.5194/egusphere-egu25-4434, 2025.
One of the major challenges in space weather forecasting is to reliably predict the magnetic structure of interplanetary coronal mass ejections (ICMEs) in the near-Earth space. In the framework of global MHD modelling, several efforts have been made to model the CME magnetic field from Sun to Earth. However, it remains challenging to deduce a flux-rope solution that can reliably model the magnetic structure of a CME. Aiming to improve the space-weather forecasting capability, we implement a new flux-rope model in “European heliospheric forecasting information asset” (EUHFORIA). Our flux-rope model includes an initially force-free toroidal flux-rope that is embedded in the low-coronal magnetic field. The embedding technique adds a significant novelty to the state-of-the-art as it preserves the continuity condition of the magnetic field at the flux-rope boundary and maintains the force-free solution of the flux rope. The dynamics of the flux rope in the low and middle corona are solved by a non-uniform advection constrained by the observed kinematics of the event. This results in a global non-toroidal loop-like magnetic structure that locally manifests as a cylindrical structure. At heliospheric distances, the evolution is modeled as a MHD process using EUHFORIA. We assess our model results on several ICMEs, including cases of interacting events. Comparing the model results with the in-situ magnetic field configuration of the ICME at 1 au, we find that the simulated magnetic field profiles of the flux-rope are in very good agreement with the in-situ observations. Therefore, the framework of toroidal model implementation as developed in this study could prove to be a major step-forward in forecasting the geo-effectiveness of CMEs.
How to cite: Sarkar, R., Pomoell, J., and Kilpua, E.: Modelling the Sun-to-Earth Propagation of CMEs Using a Novel Flux-Rope Model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11725, https://doi.org/10.5194/egusphere-egu25-11725, 2025.
Coronal mass ejections (CME) are one of the main drivers of space weather. However, quasi-realistic and efficient numerical modelling of the CME propagation and evolution process in the whole solar-terrestrial space, especially in the sub-Alfvénic corona, is still lacking. Recently, we have made some attempts to improve our ability to model CMEs. 1. We developed an efficient and quasi-realistic time-evolving MHD coronal model which can be used to provide inner-boundary conditions for the inner heliosphere models in practical space weather forecasting. 2. We developed an efficient and time-accurate MHD model of the solar corona and CME to timely and accurately simulate time-varying events in solar corona with low plasma β. 3. We developed an extended magnetic field decomposition strategy to improve the numerical stability of the time-evolving MHD coronal models in solving low-β issues. 4. We are conducting some faster-than-real-time CME simulations from the solar surface to 1 AU based on the work mentioned above. In this work, the solar-terrestrial space is covered by extending the coronal model to 1 AU or by coupling the coronal model with an inner heliosphere model. These MHD models are demonstrated to be very efficient and numerically stable and are promising to timely and accurately simulate time-varying events in solar-terrestrial space for practical space weather forecasting. I'd like to share our research work at EGU conference and call for more collaborations to perform more interesting research works.
How to cite: Wang, H., Poedts, S., Lani, A., Brchnelova, M., Linan, L., Baratashvili, T., Guo, J., Yang, L., Zhang, F., Zhou, Y., and Lin, R.: Efficient and Quasi-realistic Magnetohydrodynamic Modeling of Coronal Mass Ejection Propagation and Evolution, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15241, https://doi.org/10.5194/egusphere-egu25-15241, 2025.
Predicting the geo-effectiveness of CMEs relies on accurate modeling of their propagation and interaction with the solar wind. EUHFORIA (EUropean Heliospheric FORecasting Information Asset) is a state-of-the-art 3D magnetohydrodynamic (MHD) model designed to model the evolution of CMEs in the heliosphere. I will present the several advanced CME models implemented in EUHFORIA, including the spheromak model, Fri3D (Flux-Rope in 3D), spheromak, and two toroidal CME models (Soloviev and Miller-Turner based models). Additionally, a more recent deep learning-based model, PINN, has been developed and implemented in EUHFORIA to enable access to toroidal magnetic field distributions that are otherwise not analytically accessible or computationally expensive to obtain.
I will also present the latest advancement in EUHFORIA: its coupling with the global MHD coronal model COCONUT (COolfluid COroNal UnsTructured). While EUHFORIA injects CME models at 0.1 AU, this approach omits critical interactions occurring near the Sun, where the CME engages with the structured solar wind. COCONUT addresses this limitation by simulating the solar corona, starting from the solar surface and extending to 0.1 AU, using observed magnetograms to produce a realistic solar wind environment. This coupling enables us to track the propagation of a CME from its launch at the Sun’s surface through the corona and into the heliosphere. By aligning the outer boundary of COCONUT with the inner boundary of EUHFORIA, we ensure a seamless transfer of CME properties, including its magnetic field structure and plasma characteristics.
I will present the first results of this coupling, showcasing how different flux-rope CME models (e.g., Titov-Démoulin and RBSL) propagate dynamically through the coupled domain. This innovative integration marks a significant step forward in our ability to predict CME impacts and understand the physics driving space weather events.
How to cite: Linan, L., Baratashvili, T., Maharana, A., Guo, J., Lani, A., Schmieder, B., and Poedts, S.: Advanced flux-rope CME models in EUHFORIA and coupling with COCONUT, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17746, https://doi.org/10.5194/egusphere-egu25-17746, 2025.
CMEs interact with the solar wind and heliospheric magnetic field which influence their propagation, expansion as well as internal magnetic structure. We understand these processes on a global level, however we are still lacking a detailed qualitative and quantitative understanding of the CME evolution on a level that could result in a reliable forecast. Our limitations are influenced by uncertainties in measurements as well as uncertainties in associating remote-to-insitu events and observation-to-model comparison. These uncertainties affect not only inputs to our CME propagation models, but also evaluation of the outputs. As an example, we present the newly developed adaptation of the widely used drag-based model (DBM, Vrsnak et al., 2013) for 3D geometry, which should in theory provide more accurate forecast. However, we show that for an arbitrary evaluation sample it does not provide significantly different results from its 2D counterpart.
How to cite: Dumbovic, M.: Why doesn’t model improvement result in better forecast: the 3D drag-based model for CME propagation example, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12767, https://doi.org/10.5194/egusphere-egu25-12767, 2025.
The prevailing view of coronal mass ejections (CMEs) has long been that their magnetic field structure is best described by a highly twisted, circular cross-section magnetic flux rope model. This concept, which emerged from studies in the 1970s and 1980s, has become the foundation for most common CME depictions and has inspired various fitting models developed in the 1990s and 2000s. These models aim to provide three-dimensional visualizations of data from remote sensing and in situ measurements.
However, the landscape of CME research has evolved significantly since this paradigm's inception. A wealth of new data has emerged, including multi-point measurements, remote heliospheric observations, advanced physical models, and sophisticated numerical simulations. Collectively, these advancements have revealed that while the traditional paradigm explains certain CME characteristics, it falls short in capturing the full complexity of magnetic field structures in many instances.
This work provides a comprehensive review of four decades of continuous observations and ongoing research since the introduction of the highly twisted circular cross-section flux rope model. It proposes a more nuanced and realistic representation that better reflects the true intricacy of magnetic ejecta within CMEs. It also propses a new method to visualizing and quantifying the magnetic confuguration through the extraction of the magnetic helicity of CMEs during their journey to 1 AU, utilizing 3-D magneto-hydrodynamical (MHD) simulations.
How to cite: Al-Haddad, N., Lugaz, N., Berger, M., and Farrugia, C.: On the Complex Magnetic Topology of Coronal Mass Ejections: An Enhanced Paradigm, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19089, https://doi.org/10.5194/egusphere-egu25-19089, 2025.
Due to high solar activity, since the launch of Solar Orbiter about 5 years ago, at least 50 solar coronal mass ejection (CME) events have been observed at multiple spacecraft in situ, and more than 70 with at least one in situ and one imaging instrument. This type of measurement is of high importance for several reasons, which are relevant to improve both our basic understanding of the general nature of CMEs and to enhance our space weather forecasting capabilities. I will give an overview of the most important results so far using CME multipoint observations. They have been enabled by especially combining the in situ magnetic field observations made by Solar Orbiter, Parker Solar Probe, BepiColombo, near-Earth spacecraft at L1 and STEREO-A. We demonstrate how observations in the inner heliosphere allow us to create a power law for CME evolution seamlessly covering 0.07 to 5.4 au. We discuss results on flux rope coherence in interplanetary space, which is exceedingly relevant for understanding the 3D magnetic flux rope shape, and the applicability of upstream monitors for CME forecasting. Our living catalogs ICMECAT and LineupCAT for single and multipoint CME observations by various spacecraft are presented and are encouraged to be used by the research community. The most recent addition to the fleet of spacecraft enabling these groundbreaking observations is the PUNCH mission planned to be launched in February 2025, which enables polarized heliospheric imaging from Earth orbit. Here, new possibilities to derive the CME 3D structure in combination with in situ magnetic field observations of the same CME emerge.
How to cite: Möstl, C., Weiler, E., Davies, E. E., Rüdisser, H. T., Amerstorfer, U. V., Amerstorfer, T., Le Louëdec, J., Bauer, M., Horbury, T. S., and Lugaz, N.: Multipoint coronal mass ejection events in solar cycle 25, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13215, https://doi.org/10.5194/egusphere-egu25-13215, 2025.
Solar Energetic Particles (SEPs) represent a natural hazard for the Earth environment, from the instruments on board spacecraft to the electricity networks and astronauts life. These events are produced by solar eruptions such as flares and Coronal Mass Ejections (CMEs) that spread into the interplanetary space. In this study, we analyze energetic particle fluxes at CME-driven shocks measured in-situ by multiple satellites at different radial distances and longitudes and derive the parameters of the shocks such as the compression ratio, the angle between the magnetic field and the normal to the shock, and the Mach numbers. When it is possible, we compare these quantities with the shock parameters computed at the coronal sources using remote-sensing observations. Following the evolution of the parameters characterizing the CMEs from the source to space will help space weather models to improve predictions on the arrival of SEPs at the Earth. Magnetic field turbulence is also investigated by calculating the power spectral density, the autocorrelation function, in order to derive the turbulence correlation length and the level of magnetic intermittency. This study is achieved in the context of the research project “Data-based predictions of solar energetic particle arrival to the Earth” funded by the Italian Ministry of Research under the grant scheme PRIN-2022-PNRR.
How to cite: Chiappetta, F., Perri, S., Nisticò, G., Pucci, F., Malara, F., Sorriso-Valvo, L., and Zimbardo, G.: Analysis of the CME-driven shocks detected through in-situ measurements and remote-sensing observations by multi-spacecraft , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12587, https://doi.org/10.5194/egusphere-egu25-12587, 2025.
We conducted a comprehensive statistical analysis of the evolution of coronal mass ejections (CMEs) and their embedded magnetic obstacles with and without driving a sheath. Specifically, we explored the thermal and magnetic pressure within the different CME regions, alongside with the open solar flux (OSF) through various solar cycles. Preliminary results indicate significant differences in the fluctuations of the mean and standard deviation of the magnetic field between solar cycles 23 and 24. The analysis reveals that the sheath total pressure is higher than that of magnetic obstacles, with a notable decrease in pressure from solar cycle 23 to 24. Likewise, the OSF shows a decrease from solar cycle 23 to 24, correlating with the observed CME pressure trends. These findings suggest that the characteristics of ICME sheath regions and magnetic obstacles vary depending on the ambient solar wind conditions present during each individual cycle. This research represents an initial step towards a more comprehensive understanding of the dynamics and variability of ICME sheaths, with implications for space weather forecasting and modeling.
How to cite: Larrodera, C., Temmer, M., and Owens, M.: Investigating the Dynamics and Variability of ICME Sheaths and Magnetic Obstacles Across Solar Cycles, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6729, https://doi.org/10.5194/egusphere-egu25-6729, 2025.
A new shock-capturing tool is introduced to study the coronal mass ejection-driven shock originating from the low solar corona. Multi-spacecraft observations, including SOHO, SDO, GOES, ACE near Earth, and STEREO-A/B, are used for model-data comparison and validation. We show the simulated observables, including extreme ultraviolet and white-light images, shock properties, as well as proton time-intensity profiles and energy spectra, and compare them to observations. Our simulation results demonstrate the efficient integration of the Poisson bracket scheme with a particle solver in the Space Weather Modeling Framework (SWMF) for simulating a practical SEP event, as well as the capability of capturing a time-evolving shock surface in the SWMF.
How to cite: Liu, W., Gombosi, T., Sokolov, I., and Zhao, L. and the CLEAR Team: Not All Shocks Are Created Equal: Shock Acceleration During the 2013 April 11 Solar Energetic Particle Event, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3351, https://doi.org/10.5194/egusphere-egu25-3351, 2025.
We investigate the effects of interplanetary coronal mass ejections (ICMEs) on the interplanetary (IP) medium, namely the solar wind (SW) and the interplanetary magnetic field (IMF). Our objective is to quantify how ICMEs alter the properties of the IP medium and to determine the degree of preconditioning. The latter occurs when ICMEs modify the IP medium in a way that enables subsequent ICMEs to propagate more efficiently, experience reduced deceleration, and retain higher energy over greater distances. This phenomenon has been proposed in the past to explain some of the shortest ICME travel times, the most intense geomagnetic storms, and the highest-energy ICME ever observed in situ.
Our analysis is based on a statistical study of a carefully curated sample of events. We examine the IP medium during 48-hour intervals before and after the passage of ICMEs. On average, the post-ICME solar wind exhibits reduced density and dynamic pressure, along with increased total velocity. Meanwhile, the trailing IMF becomes more intense and displays a stronger radial alignment. These findings indicate that even relatively moderate ICMEs can significantly precondition the IP medium, potentially influencing the behavior and impact of subsequent events.
How to cite: Kajdic, P., Temmer, M., and Blanco-Cano, X.: Statistical Analysis of Preconditioning in the Interplanetary MediumInduced by Isolated ICMEs, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7448, https://doi.org/10.5194/egusphere-egu25-7448, 2025.
In this work, we use multispacecraft observations and a high-resolution numerical simulation to understand the CME event on 2021 December 4, with an emphatic investigation of its three-part structure and rotation. This event is observed as a partial halo CME from the back side of the Sun by coronagraphs and reaches the BepiColombo spacecraft and the MAVEN/Tianwen-1 as a magnetic flux-rope-like structure. It is disclosed that in the solar corona the CME, with no signatures of a prominence at the beginning, evolves into a three-part morphology. The moving and expanding CME produces the high-density front, and the CME’s differential expansion rates lead to the distinct rarefaction rates of the plasma, which results in the formation of the low-density cavity and the high-density core. It is also found that when CME arrives in the interplanetary space, the downside and the right flank of the CME moves with the fast solar wind, and the upside does in the slow-speed stream. The different parts of the CME with different speeds generate the nonidentical displacements of its magnetic structure, resulting in the rotation of the CME in the interplanetary space. These results provide new insight into interpreting CMEs ’ structures and dynamics during their traveling through the solar corona into the heliosphere.
How to cite: Yang, L., Ma, M., Shen, F., Feng, X., Shen, C., Chi, Y., Wang, Y., Xiong, M., Zhou, Y., Zhang, M., and Zhao, X.: Three-part Structure Formation & Interplanetary Rotation of Mars-Directed Coronal Mass Ejection on 2021 December 4, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14219, https://doi.org/10.5194/egusphere-egu25-14219, 2025.
Coronal mass ejections (CMEs) undergo multiple evolutionary processes during their propagation through the heliosphere, such us deformation, rotation, and erosion. These processes may result from interactions with the ambient solar wind or with other large-scale structures. However, due to the limitation of single-point measurements of solar wind plasma or interplanetary magnetic field (IMF) properties, it is extremely challenging to infer their topology or evolutionary processes that may have undergone.
Suprathermal electrons are continuously emerging from the solar corona along the IMF. They travel faster than the solar wind, and when comparing their intensity to the direction of the IMF (i.e. analysing their pitch-angle distributions, PADs), we can extract fundamental information about the IMF topology and the conditions of the solar wind plasma. Therefore, understanding the behaviour of suprathermal electron PADs during CME encounters sheds light on the IMF that these particles travelled through, which presumably corresponds to their global structure.
Extracting the information from long periods of observations of suprathermal electron PADs, however, can be challenging. Recently, Carcaboso et al. (2020) introduced a robust method to compute large number of suprathermal electron PADs from distinct missions and derive different properties from their shape. This method can, among others, characterise salient features, automatically identify various PAD types –such as bidirectional, isotropic, simple strahl, loss cone, and pancake–, and quantify the degree of anisotropy.
Recent missions like Parker Solar Probe or Solar Orbiter enable us to observe CMEs at varying heliocentric distances during the ongoing solar cycle (SC25), which is crucial to understand their evolution and topology from the initial stages to more advanced phases. This provides a unique opportunity for a thorough analysis of suprathermal electron PADs at different heliocentric distances, offering insights into how CMEs evolve and interact with the solar wind.
By applying the suprathermal electron PAD analysis method introduced by Carcaboso et al. (2020) to the unique data from the most recent heliospheric missions, this work aims to enhance our understanding of CME evolution and global topology.
Carcaboso, F., Gómez-Herrero, R., Lara, F. E., Hidalgo, M. A., Cernuda, I., & Rodríguez-Pacheco, J. (2020). Characterisation of suprathermal electron pitch-angle distributions-Bidirectional and isotropic periods in solar wind. Astronomy & Astrophysics, 635, A79
How to cite: Carcaboso, F., Verniero, J., Lario, D., Espinosa Lara, F., Szabo, A., and Gómez-Herrero, R.: What can suprathermal electron tell us about the topology and evolution of CMEs?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14429, https://doi.org/10.5194/egusphere-egu25-14429, 2025.
In the present paper, to understand the role of solar winds in the origin of the coronal mass ejections (CMEs) Phenomena we have studied the relationship between the Extreme Ultraviolet Imaging Telescope (EIT) waves phenomena with solar flares, coronal holes, solar winds, and CMEs events. The EIT/ SOHO instrument recorded 176 EIT events during the above period (March 25, 1997-June 17, 1998) and the EIT waves list was published by Thompson & Myers (2009). After temporal matching of EIT wave events with CME phenomena, we find that corresponding to 58 EIT wave events, no CME events were recorded and thus we excluded 58 EIT wave events from the present study. Out of 176 EIT wave events, only 106 are accompanied by CME phenomena. The correlation study of the speed of EIT wave events and CMEs events of 106 events shows poor correlation r= 0.32, indicating that the EIT waves and CMEs events do not have a common mechanism of origin and also indicate that some other factor is working in the formation of CMEs from EIT waves. Further, we have also matched the spatial matching EIT wave sources as indicated by Thomson & Myers (2009) with CHs and flares and found that CMEs appear to be associated with EIT wave phenomena and CHs. Earlier Verma & Pande (1989) and [3] Verma (1998) indicated that the CMEs may have been produced by some mechanism in which the mass ejected by solar flares or active prominences gets connected with the open magnetic lines of CHs (source of high-speed solar wind streams) and moves along them to appear as CMEs. Most recently Verma & Mittal (2019) proposed a methodology to understand the origin of CMEs through magnetic reconnection of CHs open magnetic field and solar flares. In the present paper, we proposed a scenario/ 2-dimensional model in which the origin of CMEs through reconnection of EIT waves and solar winds coming from the CHs and also found that the calculated CMEs velocity after reconnection of EIT waves and solar winds coming from the CHs are in very close to the observed CMEs linear velocity. We also calculated the value of the correlation coefficient between the observed linear velocity of CME events and the calculated value of CME velocity after reconnection and found the value as r=0.884. The value of correlation as r=0.884 is excellent and supports the proposed methodology. Finally, we have also discussed the role of solar wind phenomena in the formation of CMEs phenomena with other solar phenomena, in the latest scenario of solar heliophysics phenomena.
REFERENCES
Thompson, B. J. & D. C. Myers, D. C. (2009) Astrophys. J. Suppl. 183, 225.
Verma, V. K. & Pande, M. C. (1989) Proc. IAU Colloq. 104 (Poster Papers) , p.239.
Verma, V. K. (1989) J. Geophys Indian Union, 2, 65
Verma, Virendra & Mittal, N. (2019) Astronomy Letters, 45, 164-176.
How to cite: Verma, V.: Relationship among EIT Waves, Coronal Mass Ejections, Solar Flare, Coronal Holes, and Solar Wind Phenomena , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1798, https://doi.org/10.5194/egusphere-egu25-1798, 2025.
Coronal mass ejections (CMEs), originating from the sun's corona, are large-scale eruptions of plasma and magnetic flux that propagate into interplanetary space, and are capable of significantly influencing the dynamic environment of the inner solar system. Previous studies have established that CMEs exhibit turbulent behavior, characterized by energy cascades from larger to smaller scales through the formation of eddies. This study investigates the turbulence properties at different stages of a CME evolution. We divide the CME event into three intervals, characterised by the arrival of the CME shock and the magnetic cloud region. The magnetic field signal was decomposed using the method of empirical mode decomposition (EMD) into intrinsic mode functions (IMFs), which capture inherent oscillatory modes within the data. For each magnetic field component (Bx, By, Bz), we generated Fourier power spectra and Hilbert-Huang spectra, representing the power distribution across frequencies within the three intervals. These spectra can provide insights into the turbulent nature of the magnetic field during the different stages of CME evolution.
How to cite: Dagore, A., Prete, G., and Carbone, V.: Analysing Turbulence in Coronal Mass Ejections Using Empirical Mode Decomposition , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15115, https://doi.org/10.5194/egusphere-egu25-15115, 2025.
Magnetic helicity is an important concept in solar physics, with a number of theoretical statements pointing out the important role of magnetic helicity in solar flares and coronal mass ejections (CMEs). Here we construct a sample of 47 solar flares, which contains 18 no-CME-associated confined flares and 29 CME-associated eruptive flares. We calculate the change ratios of magnetic helicity and magnetic free energy before and after these 47 flares. Our calculations show that the change ratios of magnetic helicity and magnetic free energy show distinct different distributions in confined flares and eruptive flares. The median value of the change ratios of magnetic helicity in confined flares is -0.8%, while this number is -14.5% for eruptive flares. For the magnetic free energy, the median value of the change ratios is -4.3% for confined flares, whereas this number is -14.6% for eruptive flares. This statistical result, using observational data, is well consistent with the theoretical understandings that magnetic helicity is approximately conserved in the magnetic reconnection, as shown by confined flares, and the CMEs take away magnetic helicity and energy from the corona, as shown by eruptive flares.
How to cite: Wang, Q., Zhang, M., Yang, S., Yang, X., and Zhu, X.: Change Ratios of Magnetic Helicity and Magnetic Free Energy During Major Solar Flares , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5088, https://doi.org/10.5194/egusphere-egu25-5088, 2025.
The connection between coronal mass ejections (CMEs) and solar flares has been studied statistically, but the details of this relationship remain largely unknown. Soft X-rays provide us a unique depiction of eruption dynamics due to the coronal first ionization potential (FIP) bias: abundances of low FIP elements are observed to peak at flare onset, and decrease abruptly towards photospheric values during the impulsive phase before recovery. Recovery times have been linked to the time when the plasma is trapped within the magnetic field, suggesting that CMEs delay abundance recovery. This provides a useful tool for studying the characteristics and dynamics of flares and CMEs and their effects on each other.
This study aims to connect flare characteristics to CME properties using soft X-ray spectroscopy and hard X-ray imaging. The temporal evolution of plasma parameters and elemental abundances during the eruption event are analyzed with soft X-ray data from the SUNSTORM 1 X-ray Flux Monitor for CubeSats (XFM-CS). Evolution of the X-ray loop emission source is investigated with a time-series analysis of image reconstructions utilizing The Spectrometer Telescope for Imaging X-rays (STIX) instrument on board Solar Orbiter. CME kinematics are analyzed with a variety of remote-sensing data. The resulting study shows that emission from a post-CME looptop source significantly affects eruption dynamics by slowing down abundance recovery, and relates this evolution to the flare profile.
How to cite: Takala, S., Lehtolainen, A., Kilpua, E., Palmroth, M., Mitchell, J., Warmuth, A., and Huovelin, J.: Quantifying CME effects on plasma parameters and elemental abundance recovery during a flare event with X-ray spectroscopy, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8335, https://doi.org/10.5194/egusphere-egu25-8335, 2025.
Magnetic clouds (MCs) are closed magnetic structures embedded in interplanetary coronal mass ejections (ICMEs). They have physical interest by their own, and, more recently, by their Earth magnetosphere effects.
Data from the period 2008-2014 Stereo A and B (MAG, PLASTIC and SWEA PAD sensors) and from different ICME catalogues have been used to elaborate an exhaustive list of MCs.
To establish the boundaries of those MCs we have used six criteria, like a low-beta plasma or higher magnetic field intensity than the values in calm solar wind conditions.
In this presentation we show the orientation of the axis (latitude and longitude) of all MCs in that period of time as determined by the well-known Hidalgo model for their magnetic topology.
How to cite: Jiménez Cuenca, J. J., Arrazola Pérez, D., Blanco Ávalos, J. J., and Hidalgo Moreno, M. Á.: Orientation of the axis of MCs observed by STEREOs in time period 2008-2014, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11530, https://doi.org/10.5194/egusphere-egu25-11530, 2025.
The Eruptive Event Generator – Gibson-Low (EEGGL) generates an unstable 3D flux rope from a given synoptic solar magnetogram that can be inserted into magnetohydrodynamic (MHD) coronal simulations for coronal mass ejection (CME) initiation. This model has been used extensively for CME simulation, both for studying the evolution of the CME itself and for generation of solar energetic particles that propagate throughout the heliosphere. EEGGL relies on empirical fitting of test events to find the relationship between the magnetogram, CME parameters, and flux rope geometry and strength. As part of the CLEAR NASA Center of Excellence at the University of Michigan, validation and enhancement of EEGGL is a key deliverable. In this presentation, we provide results from the updated EEGGL with improvements to enhance the robust nature of the code. A statistical validation is performed comparing synthetic white-light coronal images generated by the simulation to coronagraph observations, focusing on CME speed and strength. While past publications have occasionally optimized the flux rope based on a priori knowledge, we use larger statistics from agnostic runs to evaluate model performance. Such steps prepare the model for running in a fully-automated low-latency configuration.
How to cite: Keebler, T., Zhao, L., Jin, M., Sokolov, I., and Sachdeva, N.: Evaluation of the Gibson-Low flux rope generation method in coronal mass ejection simulations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13015, https://doi.org/10.5194/egusphere-egu25-13015, 2025.
Numerical modeling of the solar wind and Coronal Mass Ejections (CMEs) is a vital tool for both space weather predictions as well as improving the understanding of CME evolution in the solar wind. We utilize the state-of-the-art 3D MHD model - Alfven Wave Solar atmosphere Model (AWSoM) and a self-consistent CME model - STITCH (Statistical Injection of Helicity Condensation) to simulate the global background solar wind plasma and initiate a CME eruption on the Sun. The STITCH method forms sheared arcades through helicity injection driven purely by photospheric magnetic field observations. These models are utilized to perform a detailed study of the structure and evolution of a CME propagating in the solar wind from the Sun to the Earth using 3D simulation results to probe multiple viewpoints in the corona and the inner heliosphere.
How to cite: Sachdeva, N., van der Holst, B., Antiochos, S., Manchester, W., Huang, Z., and Toth, G.: Evolution of Coronal Mass Ejections in the Solar Wind using Data-Driven Numerical Models, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13899, https://doi.org/10.5194/egusphere-egu25-13899, 2025.
Coronal mass ejections (CMEs) are the leading driver of space weather and it is vital for space weather forecasting to benefit from a comprehensive understanding of the conditions in which CMEs are initiated. The rotation of sunspots around their umbral center has long been considered an important condition leading to CMEs. To unveil the underlying mechanisms, we carried out a data-driven MHD simulation for the event of a large sunspot with a rotation of days in a solar active region, NOAA 12158, which produced two homologous halo CMEs. Our simulation successfully follows the long-term quasi-static evolution of the active region and the eruptions, with magnetic field structure being highly consistent with the observed coronal emission. The onset time of the simulated eruption is a very good match to the observations. The simulation shows that through the successive rotation of the sunspot, the coronal magnetic field is sheared with a vertical current sheet created progressively. Once fast reconnection sets in at the current sheet, the eruption is instantly triggered, with a highly twisted flux rope originating from the eruption, forming the CME. This data-driven simulation stresses magnetic reconnection as the key mechanism in CMEs resulting from sunspot rotation.
How to cite: Jiang, C.: Data-driven MHD simulation of a sunspot-rotating active region leading to homologous CMEs, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14094, https://doi.org/10.5194/egusphere-egu25-14094, 2025.
Filament eruptions are one of the most e ective methods for generating coronal mass ejections (CMEs) and solar flares. Consequently, understanding their triggering mechanisms and eruption dynamics is a key focus in solar activity research. This study presents a statistical analysis of filament eruption events and draws the following conclusions: 1) Quiescent filaments (QSFs) are rarely triggered by the reconnection process. When QSFs do experience reconnection, they are typically found in stronger magnetic environments. 2) Reconnection-triggered filaments produce faster CMEs compared to non-reconnection-triggered filaments, affecting both active region filaments (ARFs) and other filaments. Among these, reconnection-triggered intermediate filaments (IFs) exhibit the highest average CME velocity, surpassing ARFs. 3) Most QSFs undergo a prolonged slow rise phase without significant observable signals. The exact underlying mechanism remains unclear, but the helicity condensation theory is proposed as a possible explanation. 4) The average velocity of eruptive QSFs associated with detectable flares is higher than that of ARFs. This suggests that in weaker magnetic environments, reconnection can significantly enhance CME propagation, whereas in active regions, stronger reconnection is required to achieve similar effects.
How to cite: Zou, P.: A statistical study of solar lament eruptions based on the kinetic evolution, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14222, https://doi.org/10.5194/egusphere-egu25-14222, 2025.
Coronal Mass Ejections (CMEs) are the major sources of severe space weather events, causing potential damages to orbital and ground assets including satellites, space stations and power grids. To avoid the huge economic losses, it is crucial to understand the propagation of CMEs and derive physical parameters especially in 3-dimension for better prediction of CME propagation. We have developed an algorithm to automatically reconstruct CME structure based on double view-point observations and machine learning technique. The algorithm consists of three steps: region acquirement, model construction, function optimization. First, we train two Convolutional Neural Networks (CNNs) to identify the CME in visual observations from the Large Angle Spectrometric Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO) and the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) COR-2 Coronagraph onboard the Solar TErrestrial RElations Observatory (STEREO), respectively. The CME region information is then leveraged with the Principal Component Analysis algorithm and Otsu's method. Next, we establish the Graduated Cylindrical Shell (GCS) model and project it into the field of view of the coronagraphs. In the final step, we construct a function to measure the difference between the image of the GCS model and the CME region. Then the optimal 3D CME parameters can be obtained. Several CME events are chosen to show the accuracy and effectiveness of our method. We also conduct a statistical analysis on 127 CME events from 2007 to 2014 to investigate the 2D and 3D parameters of CMEs. Our method can be used to provide CME initial parameters in magnetohydrodymic simulations for accurate prediction and understanding of CME.
How to cite: Lin, R., Yang, Y., and Shen, F.: An algorithm to derive CME 3D parametersbased on machine learning and double view-point observation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4695, https://doi.org/10.5194/egusphere-egu25-4695, 2025.
