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Observing and Modelling the Solar Wind and CMEs Through the Heliosphere

Coronal mass ejections (CMEs), in addition to corotating density structures and solar energetic particles (SEPs), are known to be the driving force behind significant space weather disturbances at Earth and other planets. Understanding their physical behaviour and making accurate predictions about their arrival times and properties is a difficult and ongoing issue in heliophysics. Remote-sensing and in-situ measurements from multiple vantage points, combined with ground-based observations and modelling efforts, are employed to study the solar wind plasma and CMEs from their onset to their arrival at planets and spacecraft throughout the heliosphere.

Recently launched spacecraft including Parker Solar Probe, Solar Orbiter, BepiColombo, in addition to existing missions such as STEREO and future missions to L1 and L5 present an ideal opportunity to test, validate and refine current knowledge in this field. We therefore encourage submissions with the aim of exploiting the latest observational and modelling efforts regarding CME and solar wind evolution during their propagation throughout the heliosphere.

Convener: David BarnesECSECS | Co-conveners: Erika PalmerioECSECS, Rui Pinto
| Mon, 23 May, 15:10–18:30 (CEST)
Room L1, Tue, 24 May, 08:30–10:00 (CEST)
Room L1

Mon, 23 May, 15:10–16:40

Chairpersons: David Barnes, Rui Pinto, Erika Palmerio


Luke Barnard et al.

Modelling the heliospheric evolution of Coronal Mass Ejections (CMEs) is challenging and fraught with uncertainty for a range of confounding reasons. For example, there are significant uncertainties in the boundary conditions of heliospheric numerical models and such models often use CME parameterisations which are known to be overly simplistic e.g. hydrodynamic perturbations without magnetic structure. Consequently, the uncertainty on modelled CME evolution remains high and simulations often struggle to accurately represent both in-situ and remotely sensed CME observations.

Data assimilation (DA) provides a framework for merging observations and a model of a system to return simulations that better represent the true state of a system. We are exploring how to use data assimilation techniques with the white-light Heliospheric Imager (HI) CME observations to generate CME simulations that better represent the observed evolution of CMEs.

Here we present the results of a set of Observing System Simulation Experiments that begin to quantify the potential gains from assimilating HI data into the HUXt solar wind model, using a particle filter data assimilation scheme based on Sequential Importance Resampling.

We explore several specific questions: 1) By how much does the HI DA improve the simulated kinematics profiles of CMEs. 2) From which observing location are HI data best able to improve simulations of Earth directed CMEs. 3) Is it necessary to assimilate the full HI image data, or is it sufficient to assimilate HI derived data products, such as the time-elongation profile of the CME front.

How to cite: Barnard, L., Owens, M., and Scott, C.: Assessing the potential of heliospheric imager data assimilation to improve CME modelling., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5613, https://doi.org/10.5194/egusphere-egu22-5613, 2022.

Camilla Scolini et al.

We present the first statistical analysis of complexity changes affecting the magnetic structure of interplanetary coronal mass ejections (ICMEs), with the aim of answering the following questions: how frequently do ICMEs undergo magnetic complexity changes during propagation? What are the causes of such changes? Do the in situ properties of ICMEs differ depending on whether they exhibit complexity changes? 

We consider multi-spacecraft observations of 31 ICMEs carried out by MESSENGER, Venus Express, ACE, and STEREO between 2008 and 2014 during periods of radial alignment. By analyzing their magnetic properties at the inner and outer observing spacecraft, we identify complexity changes which manifest as fundamental alterations in the ICME magnetic topology, or as significant re-orientations of the ICME magnetic structure. Plasma and suprathermal electron data at 1 au, as well as simulations of the ambient solar wind enable us to reconstruct the propagation scenario for each event, and to identify critical factors controlling their evolution. 

Results show that 65% of ICMEs change their complexity between Mercury and 1 au, and that the interaction with multiple large-scale solar wind structures is the main driver of these changes. Furthermore, 71% of ICMEs observed at large radial (>0.4 au) but small longitudinal (<15 degrees) separations exhibit complexity changes, indicating that the propagation over large distances strongly affects ICMEs. Results also suggest ICMEs may be magnetically coherent over angular scales of at least 15 degrees, supporting earlier theoretical and observational estimates. This work provides statistical evidence that magnetic complexity changes are consequences of ICME interactions with large-scale solar wind structures, rather than intrinsic to ICME evolution, and that such changes are only partly identifiable from in situ measurements at 1 au.

How to cite: Scolini, C., Winslow, R. M., Lugaz, N., Salman, T. M., Davies, E. E., and Galvin, A. B.: Magnetic complexity changes within interplanetary coronal mass ejections: insights from a statistical study based on radially-aligned spacecraft observations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2833, https://doi.org/10.5194/egusphere-egu22-2833, 2022.

Paul Geyer et al.

The interaction of interplanetary coronal mass ejections (ICMEs) and stream interaction regions (SIRs) gives rise to complex heliospheric plasma and magnetic field conditions. Considering the different magnetic configurations of both phenomena as well as the source regions in the solar corona, there is also the possibility of magnetic reconnection either at coronal heights or farther out in the heliosphere.

The event of February 7th, 2014 shows clear signatures of a qualitative alteration of the ICME structure in ACE plasma and magnetic field data. There is a significant drop of the magnetic field strength inside the FR simultaneously to an enhancement in temperature and a high variability of speed. The flow angle reversal expected to take place at the stream interface sharply coincides with the onset of the ICME magnetic field rotations and drop of temperature below expected temperature. The speed inside the flux rope, yet showing the aforementioned variations, overall features a decline from the front to the rear of the ICME. The launch site of the ICME is derived from SDO AIA data, showing its location to be 30° West from a N-S elongated coronal hole.

These results imply a deterioration of the FR due to magnetic reconnection, either caused by the proximity of CH and CME eruption site and favorable magnetic configurations, or the heliospheric interaction of the associated SIR and ICME. WSA-ENLIL simulations suggest that the ICME catches up with the SIR close to Earth, which, along with the in-situ signatures, implies the simultaneous occurrence of stream interface and flux rope onset. The declining speed profile that is characteristic for quiescent ICME spatial evolution suggests no high-speed stream is inhibiting expansion from behind. Due to its complexity, this event provides a great opportunity to study the interaction of ICMEs and SIRs.

How to cite: Geyer, P., Dumbovic, M., and Temmer, M.: Case study of interacting large-scale solar wind phenomena in the heliosphere, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5063, https://doi.org/10.5194/egusphere-egu22-5063, 2022.

Sanchita Pal et al.

The orbit of the Parker Solar Probe (PSP) during the 5th encounter with the Sun presented an opportunity for a multi-observation analysis including the observations of Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) coronagraphs and Large Angle and Spectrometric Coronagraph (LASCO) coronagraphs. Streamer-blowout coronal mass ejections (SBO-CMEs) are the dominant CME population during solar minimum. With the aid of extrapolated coronal fields and remote observations of the off-limb low corona, we study the initiation of an SBO-CME preceded by consecutive CME eruptions following a multi-stage sympathetic breakout scenario. The suprathermal electron pitch-angle distributions (PADs) and magnetic field observations by PSP suggest that draping of interplanetary magnetic field lines about the CME caused a curvature in the adjacent heliospheric current sheet, initiated magnetic reconnection with the CME flux rope about ~45 hours before it encountered PSP, and eroded ~38% of its initial poloidal magnetic flux at ~0.5 AU. This study covering inner heliospheric observation and analysis of SBO-CME magnetic content provides important implications for the origin of twisted magnetic field lines in SBO-CME flux ropes as the flux rope is not perturbed much by the interplanetary propagation. Also, the multi-spacecraft observations allowed us to estimate the distances where reconnection between the flux rope and its surroundings may be initiated. 

How to cite: Pal, S., Kilpua, E., Good, S., Lynch, B., Palmerio, E., Asvestari, E., Pomoell, J., and Stevens, M.: Eruption and Interplanetary Evolution of a Stealth Streamer-blowout CME Observed at ~0.5 AU , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5544, https://doi.org/10.5194/egusphere-egu22-5544, 2022.

Emma Davies et al.

We present a catalogue of 35 interplanetary coronal mass ejections (ICMEs) observed by the Juno spacecraft during its cruise phase to Jupiter in conjunction with at least one other spacecraft at heliocentric distances near or less than 1 AU (by MESSENGER, Venus Express, Wind, or STEREO). Previous ICME catalogues are used to find conjunctions between spacecraft, and events with magnetic field features that can be matched unambiguously across different spacecraft are selected. We conduct a multi-spacecraft analysis of ICME properties between 0.3 and 2.2 AU: we first investigate the global expansion of ICMEs by tracking the variation in magnetic field strength with increasing heliocentric distance of individual events, finding significant variability in magnetic field relationships for individual events in comparison with statistical trends. With the availability of plasma data at 1 AU, local and global expansion rates are compared; despite following expected trends, the local and global expansion rates are weakly correlated. Finally, for those events with clearly identifiable magnetic flux ropes, we investigate their magnetic complexity as they propagate; we find that 60% of events undergo at least one change in complexity between observations at the innermost spacecraft and Juno. The multi-spacecraft catalogue produced in this study provides a valuable link between ICME observations in the inner heliosphere and beyond 1 AU, contributing to our understanding of ICME evolution in situ. We intend the catalogue to be a useful resource for future studies of ICMEs and space weather research at Earth and other planets.

How to cite: Davies, E., Winslow, R., Scolini, C., Forsyth, R., and Möstl, C.: Multi-spacecraft Observations of Interplanetary Coronal Mass Ejections between 0.3 and 2.2 AU: Conjunctions with the Juno Spacecraft, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12423, https://doi.org/10.5194/egusphere-egu22-12423, 2022.

Christian Möstl et al.

We present the results of a search for multipoint in situ and imaging observations of interplanetary coronal mass ejections (ICMEs) with the Heliophysics System Observatory, from 2020 April to present day. This builds up on our recent publication in ApJ Letters introducing the living ICME lineup catalog available at https://helioforecast.space/lineups. We highlight a few new lineup events captured by those spacecraft from September to November 2021, when all were located within 50 degrees east of the Sun-Earth line. Multi-messenger observations of ICME flux ropes and shocks are much needed to make progress on the understanding of the global magnetic configuration of ICMEs, space weather forecasting, the magnetic connectivity of the solar wind to the Sun and the propagation of solar energetic particles.

How to cite: Möstl, C., Weiss, A. J., Reiss, M. A., Amerstorfer, T., Bailey, R. L., Bauer, M., Barnes, D., Davies, J. A., Harrison, R. A., Davies, E. E., Heyner, D., Horbury, T. S., and Bale, S. D.: Multipoint Interplanetary Coronal Mass Ejections Observed with Solar Orbiter, BepiColombo, Parker Solar Probe, Wind, and STEREO-A, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1964, https://doi.org/10.5194/egusphere-egu22-1964, 2022.

Laura Rodríguez-García et al.

Context. Late on 2013 August 19, a coronal mass ejection (CME) erupted from an active region located near the far-side central meridian from Earth’s perspective. The event and its accompanying shock were remotely observed by the STEREO-A, STEREO-B and SOHO spacecraft. The interplanetary (IP) counterpart (ICME) was intercepted by MESSENGER near 0.3 au, and by both STEREO-A and STEREO-B, near 1 au, which were separated by 78 degrees in heliolongitude.

Aims. The main objective of this study is to follow the radial and longitudinal evolution of the ICME throughout the inner heliosphere, and to examine possible scenarios for the different magnetic flux-rope (MFR) configuration observed on the solar disk, and measured in-situ at the locations of MESSENGER and STEREO-A, separated by 15 degrees in heliolongitude, and at STEREO-B, which detected the ICME flank.

Methods. Solar disk observations are used to estimate the ‘MFR type’, namely, the magnetic helicity, axis orientation and axial magnetic field direction of the MFR. The graduated cylindrical shell model is used to reconstruct the CME in the corona. The analysis of in-situ data, specifically, plasma and magnetic field, is used to estimate the global IP shock geometry and to derive the MFR type at different in-situ locations, which is compared to the type estimated from solar disk observations. The elliptical cylindrical analytical model is used for the in-situ MFR reconstruction.

Results. Based on the CME geometry and on the spacecraft configuration, we find that the MFR structure detected at STEREO-B belongs to the same ICME detected at MESSENGER and STEREO-A. The opposite helicity deduced at STEREO-B, might be due to the spacecraft intercepting one of the legs of the structure far from the MFR axis, while STEREO-A and MESSENGER are crossing through the core of the MFR. The different MFR orientations measured at MESSENGER and STEREO-A arise probably because the two spacecraft measure a curved, highly distorted and rather complex MFR topology. The ICME may have suffered additional distortion in its evolution in the inner heliosphere, such as the west flank is traveling faster than the east flank when arriving near 1 au.

How to cite: Rodríguez-García, L., Nieves-Chinchilla, T., Gómez-Herrero, R., Zouganelis, I., Vourlidas, A., Balmaceda, L., Dumbovic, M., Jian, L., Mays, L., Carcaboso, F., Guedes-Dos Santos, L. F., and Rodríguez-Pacheco, J.: Evidence of a complex structure within the 2013 August 19 coronal mass ejection. Radial and longitudinal evolution in the inner heliosphere, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1017, https://doi.org/10.5194/egusphere-egu22-1017, 2022.

Consuelo Cid et al.

The solar storms happened in early August 1972 have been recently described as an example of a space weather event due to its technological impacts. Besides the interest of this event for the space weather community, these storms were extensively analyzed by the scientific community in 1970s and 80s due to their relevance considering the enhanced levels of solar activity and also their interplanetary consequences. The passage of several interplanetary shocks was observed in Pioneers 9 and 10 data and also in Pognoz-1, Prognoz-2 and HEOS-2 data, making this event particularly suitable for the study of the evolution of the solar ejections in the Heliosphere. This work starts reviewing the papers on the interplanetary scenario during this event. Then, we revisit their conclusions considering the scientific advances since that date and finally go ahead in the analysis of the event. 

How to cite: Cid, C., Saiz, E., and Flores-Soriano, M.: Revisiting the solar-interplanetary connection of the early August 1972 solar storms, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12553, https://doi.org/10.5194/egusphere-egu22-12553, 2022.

Gabriel Muro and Huw Morgan

High-resolution spectral diagnostic data gathered from the total solar eclipse in Neuquen, Argentina provided a rare glimpse of Fe X, XI, XIV ions approximately ~110 minues after the initial plasma eruption that led to a near side coronal mass ejection (CME). The iron ion spectral data represents equilibrium temperatures from 0.9 to 1.9 MK and lower Mg I prominences were also observed. We present a well constrained temperature map of both sides of the corona, where the CME occurred and opposite side which is relatively unperturbed.

A geometric simulation based upon Doppler mapping from our spectrometer, perpendicular motion from other cameras, and LASCO velocity estimates is utilized to find critical CME propagation parameters that extend from the low corona until secondary detection at several solar radii. This data fills the gap of spectral measurements from other space telescopes.

How to cite: Muro, G. and Morgan, H.: Post-CME spectroscopic observations during the 2020 total solar eclipse, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12699, https://doi.org/10.5194/egusphere-egu22-12699, 2022.

Virendra Verma

In the present paper, we have studied the relationship between the Extreme Ultraviolet Imaging Telescope (EIT) waves phenomena with solar flares, coronal holes, solar winds, and coronal mass ejections (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 CMEs phenomena, we find that corresponding to 58 EIT wave events, no CMEs 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 CMEs 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), 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 CMEs 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 relationship of EIT wave phenomena with other solar phenomena, in the present scenario of solar heliophysics phenomena.




Thompson, B. J. & Myers, D. C. (2009) APJS, 183, 225.
Verma, V. K. & Pande, M. C. (1989) Proc. IAU Colloq. 104 Solar and Stellar Flares (Poster Papers), Stanford University, Stanford, USA, p.239.
Verma, V. K.(1998) Journal of Geophysical Indian Union, 2, 65.
Verma, V. K. & Mittal, N.(2019) Astronomy Letters, 45, 164-176.

How to cite: Verma, V.: On Relation Between EIT Waves Phenomena with Other Solar Phenomena, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-56, https://doi.org/10.5194/egusphere-egu22-56, 2022.


Mon, 23 May, 17:00–18:30

Chairpersons: David Barnes, Rui Pinto, Erika Palmerio

Johannes Z. D. Mieth et al.

Based on measurements of the magnetometer MPO-MAG on board the spacecraft BepiColombo on its way to Mercury, we present a statistical overview on Alfvénic structures in the interplanetary magnetic field (IMF) in the inner solar system between approx. 0.3 – 1 AU and their implication on the offset calibration accuracy of space-borne magnetometers.
Different properties of the Alfvén waves are examined and statistically compared to each other, as are for example: orientation of the wave plane, orientation of the main magnetic field.
In addition to the spatial properties, the temporal properties like stability, occurrence rate and typical timescales of Alfvén Waves are also studied.
To highlight possible differences of the IMF between the inner Solar System and at Earth-distance, results are then compared to measurements of the Moon-orbiting ARTEMIS probes.

How to cite: Mieth, J. Z. D., Hilgers, Y., Heyner, D., Glassmeier, K.-H., and Plaschke, F.: Statistics on Alfvénic Structures of the Solar Wind in the inner Solar System, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6941, https://doi.org/10.5194/egusphere-egu22-6941, 2022.

Keiichi Ogasawara et al.

The velocity distribution functions (VDFs) of pickup He+ ions near a Coronal Mass Ejection (CME) are expected to be extremely variable due to the specific source particle distributions and the interactions with the shock passage, turbulence, and large scale magnetic structures. One of the most eminent examples is the shock injection process. Around interplanetary (IP) shocks, significant abundance enhancements of He+ pickup ions over He++ ions of solar wind origin (e.g., Chotoo et al., 2000) provided compelling evidence that the source population for the energetic particle population is not the solar wind itself, but rather the pickup ion population that contains more particles beyond the injection threshold due to the difference in VDF. However, due to the lack of high-resolution measurements of pickup ion’s energy and phase space densities, their kinetics are not well understood.

In this study, VDFs of He+ pickup ions are investigated for a typical quasi-perpendicular shock observed in the heart of the helium focusing cone. In order to calculate the VDFs of helium ions, pulse height information from each ion event in the PLasma And SupraThermal Ion Compostion (PLASTIC) instrument (Galvin et al., 2008) on the Solar Terrestrial Relations Observatory (STEREO) was utilized. During each electrostatic analyzer energy-per-charge (E/q) step (128 steps, 435.6 ms each), PLASTIC stores 512 raw pulse height events including E/q, time-of-flight, total energy, and arrival direction. This allows us to reproduce partial 3-dimensional VDFs for various ion species with ~2° angular resolution (Taut et al., 2018). Moreover, the concentration of He+ ions in the helium focusing cone increased the count rate significantly, and provided enough counting statistics to achieve 10 min cadence.

The IP shock that we focus on was driven by a coronal mass ejection producing a fast mode shock. Our study focuses on two regions: (1) VDFs within the CME sheath in the shock downstream, and (2) VDFs in the magnetic cloud. VDFs are analyzed in terms of particle heating/cooling, acceleration/deceleration, and pitch angle diffusion. The connectivity to the shock will also be investigated. In the far downstream region, correlation between the VDFs and the ambient magnetic field activities (the power spectra and the Alfvénic activity) are discussed in terms of how they modify the He+ pitch angle distributions.


Chotoo, K., et al. (2000), The suprathermal seed population for corotating interaction region ions at 1 AU deduced from composition and spectra of H+, He++, and He+ observed on Wind, doi:10.1029/1998JA000015.

Taut, A., et al. (2018), Challenges in the determination of the interstellar flow longitude from the pickup ion cutoff, doi: 10.1051/0004-6361/201731796.

Galvin, A.B., Kistler, L.M., Popecki, M.A. et al. The Plasma and Suprathermal Ion Composition (PLASTIC) Investigation on the STEREO Observatories. Space Sci Rev 136, 437–486 (2008). https://doi.org/10.1007/s11214-007-9296-x


How to cite: Ogasawara, K., Klecker, B., Kucharek, H., Dayeh, M., and Ebert, R.: The pickup He+ velocity distributions embedded in a CME structure, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10425, https://doi.org/10.5194/egusphere-egu22-10425, 2022.

Angelo Valentino and Jasmina Magdalenic

We present the evolution of the CME/flare event observed on 2021, October 28 . The GOES X1.1 class flare originated from the active region NOAA AR 2887, situated at the moment of eruption close to the central meridian. The full halo CME had also on disc signatures, i.e. the EIT wave and coronal dimming and was associated with the white light shock and the type II radio burst. The CME propagated with the projected line of the sight speed of about 1100 km/s and it seemed to be Earth directed.

However, only the associated shock wave was observed by the DSCOVR in-situ instruments, in the morning of October 31. The observations indicate that the CME’s propagation direction had a strong southward component, which induced only glancing blow and not a direct impact to Earth.

We reconstructed the CME, using SOHO/LASCO and STEREO/COR observations, and modeled it’s propagation in the inner heliosphere employing recently developed heliospheric model EUHFORIA (EUropean Heliospheric FORecasting Information Asset, Pomoell & Poedts, 2018).  After accurately modeling the observed CME we also made the ensemble runs with EUHFORIA to study how the changes of the propagation direction of the CME influence its impact to Earth.

How to cite: Valentino, A. and Magdalenic, J.: Modeling of the CME on 2021 October 28, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8017, https://doi.org/10.5194/egusphere-egu22-8017, 2022.

Marcel Ayora Mexia and Teresa Nieves-Chinchilla

In heliophysics, a flux rope could be defined as a confined magnetized plasma within magnetic field lines wrapping around an axis in a twisting but not necessarily a monotonic way. Nieves-Chinchilla et al. 2016, 2018 describes a flux rope model built on the flexibility of a non-orthogonal coordinate system that adds complexity in the magnetic structure with the  incorporation of current density components that are generalized in a polynomial series. This work aims to develop a methodology to explore the current density distribution within the helispheric flux ropes that will serve as constraint to the flux rope modeling and 3D reconstruction as well as to add understanding on the flux rope formation and evolution in the solar wind. 

How to cite: Ayora Mexia, M. and Nieves-Chinchilla, T.: Studying the internal topology of Heliospheric Flux-ropes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-434, https://doi.org/10.5194/egusphere-egu22-434, 2022.

Samuel Capellas Coderque and Teresa Nieves-Chinchilla

Heliospheric magnetic flux ropes (MFRs) are usually considered to be the magnetic structure that dominates the transport of mass and energy from the Sun into the heliosphere. They entrain a confined plasma within a helically organized magnetic topology, transporting magnetic flux and helicity into the heliosphere, as well as being the main driver of geomagnetic activity.

Following the methodology introduced by Florido-Llinas. et. al. (Sol. Phys. 295, 118, 2020) we carry out a further study to evaluate the effect of distortions in MFR stability in the heliosphere. This way, we gain an insight in the understanding of the dynamical processes ruling the propagation and evolution of MFRs in the interplanetary medium, in a view to improve our space weather forecasting capability.

How to cite: Capellas Coderque, S. and Nieves-Chinchilla, T.: Study of heliospheric magnetic flux rope instabilities driven by distortions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-435, https://doi.org/10.5194/egusphere-egu22-435, 2022.

Jordi Jumilla Lorenz and Teresa Nieves-Chinchilla

Heliospheric magnetic flux ropes (MFRs) are usually considered to be the magnetic structures in the solar wind confining plasma in a static or dynamic equilibria. They are also associated with the internal structure of the Coronal Mass Ejections (CMEs), the main drivers of geomagnetic activity. In the Heliosphere, MFRs can be described as straight axial-symmetric geometry with a variation with radius and angle of pressure and magnetic field.

Several missions such as STEREO or Solar Orbiter provide in-situ measurements of such magnetic structures. A well-known method to analyse them is the Grad-Shafranov reconstruction technique. In this article we provide a detailed overview, review of its variations and improvements and analysis of new events using this technique. Both quantitative and qualitative classification of such MFRs is done according to its orientation, shape and magnetic field and pressure profiles.

Based on the flux rope model described by Nieves-Chinchilla et al. (2018), we also investigate the physical characteristics and the underlying basic equilibrium state.

How to cite: Jumilla Lorenz, J. and Nieves-Chinchilla, T.: The Grad-Shafranov reconstruction technique: overview, improvements and analysis, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-437, https://doi.org/10.5194/egusphere-egu22-437, 2022.

Chin-Chun Wu et al.

Geomagnetic storms are one of the most important terrestrial space weather events and often commence in association with the arrival of coronal mass ejections (CMEs). When a CME is explosively released into the heliosphere, a shock wave can be formed in front of the dense, supersonic CME material. Thus, the first indication of the arrival of a CME at the Earth is a sudden increase in the global magnetic intensity due to magnetospheric compression by the CME-driven shock. Predictions of the arrival of the shock are a key element in space weather forecasting. Several different variety of methods, including numerical simulations, have been applied to predict the shock arrival time but with mediocre results, with an average uncertainty of ~10 hr. In this study we will use magnetohydrodynamic (MHD) simulations (Wu et al., 2020) to examine a number of input parameters such as the CME initial speed and release time in MHD simulation of CMEs and demonstrate their effect on the shock arrival time. We also explore effects of CME-CME interactions on the propagation of the CME/shock events. The multiple CME events that occurred during 6-29 July 2012 are simulated to highlight the importance of these factors on the prediction of shock arrival time using MHD simulations.

How to cite: Wu, C.-C., Liou, K., and Wood, B.: Magnetohydrodynamic simulation of multiple coronal mass ejection (CME) events: Effects of input parameters and CME-CME interactions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10862, https://doi.org/10.5194/egusphere-egu22-10862, 2022.

Keiji Hayashi et al.

One of the important challenges in the field of space weather study is to predict the arrival time of the shocks associated with the interplanetary coronal mass ejections (ICMEs). In many Sun-to-Earth magnetohydrodynamic (MHD) simulations, a numerical perturbation mimicking the initial stage of the CME/ICME event is given at a position of corresponding coronal event in a steady state of the solar corona and/or solar wind. Then, the temporal evolution of the perturbed solar corona and solar wind are simulated. The numerical perturbation is a critical component in this kind of CME simulation model.

Recently we have developed a new model suite combining our two existing MHD models, one is for the solar corona (Hayashi, 2005 ApJ 161:480) and the other is for solar wind (Wu+, 2012 Solar Physics 295:25; Wu+ 2020 JASTP 201:105211). In this model suite, plasma perturbations expressed with Gaussian spatial distribution and several parameters are given to initiate the CME/ICME simulation. For better simulating the Sun-Earth CME and ICME propagation, we made an iterative Newton-Raphson type minimization module for optimizing the perturbation parameters such that the differences in the CME speed within r < 30 Rsun and the arrival time of the CME-driven shocks at the Earth between the observation and simulation will be reduced simultaneously. We will report the results, in particular, which kinetic, thermal, and/or magnetic parameters are most important for numerically reproducing the ICMEs propagation from corona to 1 AU in this analysis study.

How to cite: Hayashi, K., Wu, C.-C., and Liou, K.: Optimization of parameters of CME initiation in the MHD simulation suite, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-899, https://doi.org/10.5194/egusphere-egu22-899, 2022.

Tibor Torok et al.

As suggested by Isenberg and Forbes (2007) and demonstrated numerically by Kliem et al. (2012), the Lorentz forces stemming from the interaction of the axial current in an erupting magnetic flux rope (MFR) with an ambient magnetic-field component that has the same orientation as the initial MFR axis leads to a rotation of the top part of the MFR about its rise direction. In principle, the same mechanism can be applied to CMEs that propagate in a unipolar radial field in the corona or inner heliosphere. In such cases, however, the corresponding forces should not lead to a rotation, but to a deflection of the CME front, thereby significantly altering the CME's magnetic orientation. Apart from a brief consideration in Lugaz et al. (2011), such deflections have, to the best of our knowledge, not yet been studied systematically. 

Here we employ three-dimensional (3D) idealized magnetohydrodynamic (MHD) simulations to investigate this effect in background fields of increasing complexity. We first consider a freely expanding toroidal MFR in a uniform background field, as well as the propagation of a compact, line-tied MFR in a unipolar radial field. In both cases, we find significant deflections. We then use a more realistic setup, in which we erupt an MFR from a localized, bipolar source region into a global dipole field and solar wind, which allows for a significant expansion of the MFR before it encounters open field. We perform a parametric study in which we vary the location and magnetic orientation of the source region, as well as the handedness (helicity sign) of the MFR. In this presentation, we discuss the influence of these parameters on the CME trajectory.

How to cite: Torok, T., Ben-Nun, M., Downs, C., Titov, V. S., Caplan, R. M., and Lionello, R.: Deflection of CMEs in Different Background Magnetic Fields , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2040, https://doi.org/10.5194/egusphere-egu22-2040, 2022.

Talwinder Singh et al.

Coronal mass ejections (CMEs) are responsible for extreme space weather which has many undesirable consequences to our several space-based activities. The arrival time prediction of CMEs is an area of active research. Many methods with varying levels of complexity have been developed to predict CME arrival. However, the mean absolute error in the predictions have remained above 12 hours even with the best methods. In this work, we develop a method for CME arrival time prediction that uses magnetohydrodynamic simulations of a data constrained flux rope-based CME model which is introduced in a data driven solar wind background. We found that for 6 CMEs studied in this work, the mean absolute error in arrival time was 8 hours. We further improved the arrival time predictions by using ensemble modeling and comparing the ensembles with STEREO A and B heliospheric imager data by creating synthetic J-maps from our simulations. A machine learning method called lasso regression was used for this comparison. Our mean absolute error was reduced to 4.1 hours after using this method. This is a significant improvement in the CME arrival time prediction. Thus, our work highlights the importance of using machine learning techniques in combination of other models for improving space weather predictions.

How to cite: Singh, T., Benson, B., Raza, S., Kim, T., and Pogorelov, N.: Improving the Arrival Time Prediction of Coronal Mass Ejections using Magnetohydrodynamic Ensemble Modeling, Heliospheric Imager data and Machine Learning, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13167, https://doi.org/10.5194/egusphere-egu22-13167, 2022.

Andreas Wagner et al.

To better predict the impacts of solar eruptions on Earth, understanding the low-corona evolution of CMEs is crucial because this influential early phase is highly dynamic. We therefore investigate the evolution of CME properties, such as the evolution of flux rope footpoints as well as the magnetic flux enclosed in the flux rope, during this stage of the eruption. To simulate the eruption we make use of the data-driven time-dependent magnetofrictional method (TMFM), which has been proven to accurately capture a flux rope's early evolution and lift-off. We then developed a semi-automatized method for identifying the flux rope and extracting these flux ropes from 3D data cubes and tracking their evolution in time. The extraction algorithm is based on the twist parameter Tw in a 2D plane close to the polarity inversion line as a proxy for the flux rope and its temporal evolution. It is then applied to TMFM simulations of the active region AR12473, which produced an eruption on 28th of December 2015 (see e.g., Price et al, 2020). This CME was also accompanied by an M1.9 flare, that peaked at about 12:45 UT. The extracted flux rope footpoints are then compared against observational data from SDO's AIA instrument in the 1600 Å wavelength. This comparison yields a very good match with coverage parameters (see Asvestari et al, 2019) in the range of 60-70 %. The magnetic flux is extracted from the footpoints that are rooted in one specific polarity region. 

How to cite: Wagner, A., Kilpua, E., Price, D. J., Pomoell, J., Kumari, A., Daei, F., and Sarkar, R.: Data-driven modelling of the evolution of CME properties in the low-corona: AR12473, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3474, https://doi.org/10.5194/egusphere-egu22-3474, 2022.

Andreas Weiss et al.

We present our most recent results for an analytical flux rope model that includes the effects of curvature and torsion on the magnetic field. Our analytical model consists of a cylindrical flux rope that can be bent or twisted in any manner under the condition of axial and poloidal flux conservation. We can furthermore configure our model to exhibit any arbitrary radial twist distribution but we do not necessarily assume the structure to be force-free. The approach can serve as a first stepping point to better model the deformations of ICME flux ropes that are expected to occur due to longitudinal velocity differentials in the solar wind. It is briefly discussed how this model can be implemented in real-world simulations and how it can be extended to non-cylindrical shapes.

How to cite: Weiss, A., Nieves-Chinchilla, T., Möstl, C., Reiss, M., Hinterreiter, J., Amerstorfer, T., and Bailey, R.: Analytical Modelling of Curved Cylindrical Flux Ropes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8406, https://doi.org/10.5194/egusphere-egu22-8406, 2022.


Tue, 24 May, 08:30–10:00

Chairpersons: David Barnes, Rui Pinto, Erika Palmerio

Barbara Perri et al.

Space weather has the difficult task to try to anticipate the propagation of eruptive events such as coronal mass ejections (CMEs) in order to assess their possible impact on the Earth’s space environment. This requires an accurate description of the background in which CMEs propagate, mainly the continuum ejecta of particles that is the solar wind and the dynamo-generated heliospheric magnetic field. This proves challenging as the solar wind and dynamo magnetic field are interacting with each other depending on the activity cycle of our star, both at large and small scales. To be able to model accurately such a wide variety of scales and parameter regimes, the approach used by the EUHFORIA 2.0 project is to use a chain of models, taking advantage of existing codes to combine their strengths through numerical coupling across the heliosphere. The first step of this chain is the data-driven modeling of the inner corona, from photosphere measurements up until 0.1 AU, and it proves especially critical as it serves as boundary condition for the rest of the models.


In that regard, we will present here two coronal MHD models implemented as an alternative to the semi-empirical WSA and SCS models used so far in EUHFORIA. By using the COOLFluiD framework, we developed a new coronal model with implicit solving methods and unstructured meshes, which proves faster than traditional explicit methods on regular grids. We used the coronal code Wind-Predict to benchmark this new model for the simple polytropic approximation in the first place, and we present the similarities and differences obtained for data-driven configurations and compare them with observations (white-light images, coronal hole boundaries, in-situ data at 1 AU after coupling with EUHFORIA). We then present the improvements foreseen for each codes, especially for the heating terms: Wind-Predict will incorporate self-consistent Alfvén waves while COOLFluiD will use ad-hoc heating terms and a multi-species treatment. We will finally discuss the implications for the coupling with EUHFORIA and the CME propagation between 0.1 and 1 AU.

How to cite: Perri, B., Leitner, P., Brchnelova, M., Baratashvili, T., Kuzma, B., Zhang, F., Lani, A., Poedts, S., Kochanov, A., Samara, E., Brun, A. S., and Strugarek, A.: Multi-ensemble MHD coronal modeling to improve background wind for CME propagation for EUHFORIA 2.0, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1124, https://doi.org/10.5194/egusphere-egu22-1124, 2022.

Benjamin Lynch et al.

We present a comprehensive analysis of the three-dimensional magnetic flux rope structure generated during the Lynch et al. (2019, ApJ 880, 97) magnetohydrodynamic (MHD) simulation of a global-scale, 360 degree-wide streamer blowout coronal mass ejection (CME) eruption. We create both fixed and moving synthetic spacecraft to generate time series of the MHD variables through different regions of the flux rope CME. Our moving spacecraft trajectories are derived from the spatial coordinates of Parker Solar Probe’s past Encounters 7 and 9 and future Encounter 23. Each synthetic time series through the simulation flux rope ejecta is fit with three different in-situ flux rope models commonly used to characterize the large-scale, coherent magnetic field rotations observed in a significant subset of interplanetary CMEs (ICMEs). We present each of the in-situ flux rope model fits to the simulation data and discuss the similarities and differences in the model flux rope spatial orientations, field strengths, and magnetic flux content. We compare in-situ model properties to those calculated with the MHD data for both classic bipolar and unipolar ICME flux rope configurations as well as more problematic profiles such as those with a significant radial component to the flux rope axis orientation or profiles obtained with large impact parameters. We find general agreement among the in-situ flux rope fitting results for the classic profiles and much more variation among results for the problematic profiles. We also present a comparison between the MHD simulation data and the in-situ model flux ropes in a hodogram representation of the magnetic field rotation. We conclude that the in-situ flux rope models are generally a decent approximation to the field structure, but all the caveats associated with in-situ flux rope models will still apply (and perhaps moreso) at distances below 30Rs. We discuss our results in the context of future PSP observations of CMEs in the extended corona.

How to cite: Lynch, B., Al-Haddad, N., Yu, W., Palmerio, E., and Lugaz, N.: On the utility of flux rope models for CME magnetic structure below 30Rs, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6205, https://doi.org/10.5194/egusphere-egu22-6205, 2022.

Fan Zhang et al.

Space weather forecasting requires precise estimation of the arrival time of eruptive events, which typically propagate through and interact with the solar atmosphere and solar wind. Therefore, the arrival time estimation depends on the accuracy of modelling the solar atmosphere and the complex interactions. For instance, the EUHFORIA 2.0 project expects an accurate and efficient coronal model that covers the region from the surface of the Sun up to 0.1AU, serving as the inner boundary condition for the heliospheric model.

Based on the open-source code COOLFluiD, we have developed a fully implicit MHD coronal model. The model has been validated by data-driven coronal simulations, and the fully implicit temporal solution significantly accelerates the numerical simulations. More physical mechanisms, e.g., the heating term(s), and numerical techniques, e.g., high-order schemes, are being developed to improve this model further. In this work, we specifically focus on the numerical flux schemes (Lax-Friedrichs, HLL, etc.) of the finite-volume MHD solver used by the coronal model, and evaluate their performance and impact on the coronal simulations. Both the internal structures and the quantities at the outer boundary are quantitatively compared.

This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 870405 (EUHFORIA 2.0).


How to cite: Zhang, F., Perri, B., Brchnelova, M., Baratashvili, T., Kuźma, B., Leitner, P., Lani, A., and Poedts, S.: Evaluations of Numerical Flux Schemes of a Coronal MHD Model, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6012, https://doi.org/10.5194/egusphere-egu22-6012, 2022.

Michaela Brchnelova et al.

Global magnetohydrodynamic (MHD) computational fluid dynamics (CFD) simulations have become an important tool for solar weather research. These simulations use solar magnetogram data to compute structures in the solar corona. We have developed one such model based on the COOLFLuiD platform and validated it through comparison with other state-of-art codes and observations (Leitner et al., 2022, submitted). Currently, further physics is added to the solver to move it from ideal MHD to full MHD, such as radiation, coronal heating or conduction. Description of this physics and its results is what is most usually discussed in papers concerning coronal MHD CFD. 

However, physics is only one part of the solution when CFD is used. Actually, it is the numerics that is oftentimes the limiting factor, setting constraints on the accuracy and speed of these solvers. Many different problems can arise due to the finite discretisation of the domain or even due to the solver working with simplified ideal MHD equations instead of the full ones. It is rarely discussed what type of a computational grid should be used depending on the type of the simulations at hand, and it is mentioned even less often what type of errors and inaccuracies such an inappropriate grid type can cause. An unsuitable grid can also cause convergence problems and decrease the speed of the solver considerably (Brchnelova et al., 2022, submitted).

In our work, we investigate the sources of inaccuracies and errors which can compromise the global coronal MHD CFD results. We have observed that due to the large ranges of density magnitudes involved, spurious numerical fluxes can result on mesh cell interfaces when these cells are either highly skewed or the boundaries otherwise non-orthogonal. These spurious fluxes can create local errors of up to 40% in the velocity field in the most deformed portions of the computational grid. Further inaccuracies were observed also in the sharpness of the resulting velocity structures, this time due to artificially generated electric fields during the simulation. 

Thus, in our talk, we will summarize the most important of the issues observed, their causes and potential means of their mitigation. For controlling the errors due to the spurious fluxes while simultaneously optimizing the performance of the solver, we will show a trade-off between different grid topologies and what to expect in the results. Similarly, to enhance the sharpness of the features, it will also be discussed how to mitigate the generation of artificial electric fields via careful formulation of the initial state and boundary conditions.

How to cite: Brchnelova, M., Zhang, F., Perri, B., Lani, A., and Poedts, S.: Of mesh artefacts and electric fields: the bane of numerical global coronal modelling, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12255, https://doi.org/10.5194/egusphere-egu22-12255, 2022.

Emanuele Cazzola et al.

In this work we present some results from 3D hybrid simulations of the interaction between extreme solar events, such as Coronal Mass Ejections (CMEs) or Co-rotating Interaction Regions (CIRs), and a 3D Earth-like geo-environment. The events are generated and let evolve self-consistently in order to represent their typical realistic Earth-hitting characteristics as described by the averaged profiles obtained from decades of observations at 1 AU. Both shock-less and shock-driven configurations are considered to highlight the differences between the two scenarios in terms of their kinetic dynamics, as well as in terms of the effects on the Bow-Shock / Magnetosheath / Magnetosphere system.

How to cite: Cazzola, E., Fontaine, D., and Savoini, P.: 3D Hybrid Simulations of the Interaction between Self-Consistently Generated Extreme Solar Events and the Terrestrial Geo-Environment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2755, https://doi.org/10.5194/egusphere-egu22-2755, 2022.

Evangelia Samara et al.

Coronal models, usually extending between the solar photosphere and ~30 Rs, are an integral part of many space weather forecasting tools. They reconstruct the magnetic field in the solar corona and provide the necessary plasma conditions for initiating heliospheric models such as EUHFORIA or Enlil. A big gap in literature is identified when it comes to the validation of such models because of lack of observations, especially in situ. Nevertheless, the launch of the Parker Solar Probe (PSP) has provided, for the first time, in situ observations very close to the Sun that can help with the evaluation of such models. In this work, we aim to calibrate the Wang-Sheeley-Arge (WSA) semi-empirical formula used in EUHFORIA for the reconstruction of plasma and magnetic parameters at 0.1 AU. We exploit PSP in situ measurements between 0.1 – 0.4 AU obtained from the first 8 perihelia. We show how a parametric study of the WSA formula influences the velocity and density distributions very close to the Sun, how the modeled distributions are compared to PSP observations and present the relevant forecasting results at PSP and Earth.

How to cite: Samara, E., Arge, C. N., Pinto, R. F., Poedts, S., Magdalenic, J., and Rodriguez, L.: Calibrating the WSA velocity in EUHFORIA based on PSP observations, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9583, https://doi.org/10.5194/egusphere-egu22-9583, 2022.

Alexandros Koukras et al.

Although the sources of the fast solar wind are known (the coronal holes), the exact acceleration mechanism of the fast solar wind is still not fully understood. An important factor that can improve our understanding is the combination of remote sensing and in-situ measurements.

In order to combine them, it is necessary to accurately identify the source location of the in-situ solar wind with a process called back-mapping. Back-mapping consists mainly of two parts.
The first one is the ballistic mapping where the solar wind radially draws the magnetic field into the Parker Spiral, down to a point in the outer corona.
The second one is the magnetic mapping where the solar wind follows the magnetic field line topology down to the solar surface. The magnetic field in this region is derived from a global model, like the potential field source surface extrapolations (PFSS).

In this study we focus on this back-mapping of the fast solar wind and try to determine all the uncertainties and sources of error that can affect the final location deduced on the solar surface. We compare different models for the ballistic mapping and also for the magnetic mapping and explore which free parameters have the greatest effect in the back-mapped locations.
Finally, we provide an uncertainty estimation for the back-mapped footpoints and compare our results with existing frameworks, like the Connectivity-Tool of IRAP.

How to cite: Koukras, A., Keppens, R., and Dolla, L.: Estimating uncertainties in the back-mapping of the fast solar wind, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10570, https://doi.org/10.5194/egusphere-egu22-10570, 2022.

Rui Pinto

The solar wind is an uninterrupted flow of highly ionised plasma that is accelerated in the low solar corona and expands into the interplanetary space. Wind streams develop and are accelerated at different places of the strongly magnetised low solar atmosphere, before propagating through the less magnetically-dominated heliosphere. A wide range of space weather phenomena depend strongly on the structure and geometry of the solar wind flow, as well as on specific properties of the magnetic field that it crosses.
Determining the impacts of solar wind phenomena on Earth or at spacecraft locations require being able to causally link remote observations to in-situ measurements, or to predict Sun-to-spacecraft connectivity with accuracy.
I will discuss the impact of uncertainties in the determination of the magnetic field structure, of the solar wind acceleration profiles and of the rotational state of the corona as well as of mild coronal variablity. I will also highlight undergoing developments that aim at improving these tools, both on a physics-oriented perspective and in the frame of data-driven real-time monitoring.

How to cite: Pinto, R.: On combining background solar wind models and sun-to-spacecraft connectivity in the Parker Solar Probe and Solar Orbiter era, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10573, https://doi.org/10.5194/egusphere-egu22-10573, 2022.

Anwesha Maharana et al.

Coronal mass ejections (CMEs) are large scale magnetized plasma eruptions from the Sun that propagate to Earth and cause disruptions in space and ground-based technologies. While propagating through the heliosphere, they undergo interaction with other CMEs, as well as structures in the solar wind like high-speed streams, and co-rotating/stream interaction regions. We present a case-study of two Earth-directed interacting CMEs that erupted from the Sun on September 8, 2014, and September 10, 2014, respectively. While the first CME was a side hit, it is the second CME which is the focus of this study. With remote observations of the CME helicity and tilt, the second CME was predicted to be geoeffective. However, a mismatch in the tilt of the second CME was observed close to Earth, pointing to CME rotation during its propagation. Unexpectedly, the ejecta resulted in positive Bz but a geoeffective sheath was developed during the evolution and the interaction in the heliosphere that resulted in a minimum Dst ~ -100nT at Earth. Hence, the geoeffectiveness of the various sub-structures involved in this event was mispredicted. 

It is challenging to capture the complete picture of the CME and solar wind dynamics with in-situ observations taken at sparse localized points in the heliosphere. Therefore, we perform 3D MHD simulations that provide a global picture, making it convenient to probe into the interesting phenomena of this event. With the EUropean Heliosphere FORecasting Information Asset (EUHFORIA), we model the background solar wind in 3D, launch the flux rope CMEs in it and let the CME evolve till Earth. In this work, we aim to reproduce the observed plasma and magnetic field properties, especially the negative Bz of the sheath and the positive Bz of the ejecta at Earth. We address the possible factors and processes responsible for the development of geoeffectiveness from the CME rotation, the interplay of the two CMEs and the heliosphere. 

This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870405 (EUHFORIA 2.0)

How to cite: Maharana, A., Scolini, C., Schmiede, B., and Poedts, S.: Modelling CME rotation during propagation in the heliosphere with EUHFORIA, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5935, https://doi.org/10.5194/egusphere-egu22-5935, 2022.

Ranadeep Sarkar et al.

Coronal mass ejections (CMEs) are one of the major sources for space weather disturbances. If the magnetic field inside an Earth-directed CME, or its associated sheath region, has a southward-directed north-south magnetic field component (Bz), then it interacts effectively with the Earth’s magnetosphere, leading to severe geomagnetic storms. Therefore, it is crucial to predict the strength and direction of Bz inside Earth-impacting interplanetary CMEs (ICMEs) in order to forecast their geo-effectiveness. Since the magnetic field of solar eruptions cannot reliably be measured via remote means, and direct continuous measurements of the Earth impacting solar transients are routinely available only very close to our planet, modelling of magnetic properties is paramount. The state-of-the art global heliospheric MHD models typically use the spheromak to characterize the magnetic structure of a CME and simulate its evolution from Sun-to-Earth. However, recent studies (Asvestari et al. 2021) have reported that the spheromak tends to rotate due to its interaction with the ambient medium, posing a great challenge in space weather forecasting.  

In this work, we study the spheromak rotation by modelling a realistic CME event on 2013 April 11 using the “European heliospheric forecasting information asset” (EUHFORIA). We found that when using the default density value in EUHFORIA, the axis of symmetry of the spheromak undergoes approximately 90 degrees of rotation and nearly aligns to the propagation direction of the CME. However, if we constrain the spheromak density using the observational data, we find an order of magnitude higher density value as compared to the default one. Interestingly, the spheromak rotation is observed to be reduced for higher densities. However, we note that the high-density spheromaks undergo significant compression as compared to the low-density ones. Using the observationally constrained density values, we obtain good agreement between the model result and in-situ observation. The simulation is also able to capture the overall magnetic structure of the associated sheath region ahead of the CME flux rope. These results are promising towards forecasting of Bz in near real time inside both ICME and sheath regions.  

This research has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 870405 (EUHFORIA 2.0). 

How to cite: Sarkar, R., Pomoell, J., Kilpua, E., Asvestari, E., Wijsen, N., Maharana, A., and Poedts, S.: Studying the spheromak rotation for realistic CME modelling with EUHFORIA and its dependency on initial model parameters , EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11208, https://doi.org/10.5194/egusphere-egu22-11208, 2022.

David Barnes

The Heliospheric Expert Service Centre (H-ESC), part of ESA’s space weather service network, serves to provide existing heliophysics models for the provision of alerts and forecasts of space weather conditions at Earth and throughout the heliosphere. This is achieved by means of remote sensing and in-situ measurements of space weather transients, including Coronal Mass Ejections and high-speed solar wind streams, combined with advanced MHD modelling to predict their arrival times at points of interest in the heliosphere. Two such models include the European Heliospheric Forecasting Information Asset (EUHFORIA) and the ENLIL model operated by the UK Met Office, both of which are currently federated through the H-ESC portal. As a means to test both models, we perform daily runs of the EUHFORIA model using the same inputs (GONG magnetograms and CME cone-files) as the Met Office ENLIL simulations since the beginning of 2019, which are compared to real solar wind observations near Earth. We employ well-established model validation methodology by deriving contingency tables and the associated skill scores for both models as a means to assess their ability to make accurate space weather forecasts during this period of parallel operation.

How to cite: Barnes, D.: Assessment and Validation of Daily Enlil and EUHFORIA Simulations During 2019–2021, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5676, https://doi.org/10.5194/egusphere-egu22-5676, 2022.