Coronal holes (CH) are large, long-lived structures commonly observed in the solar corona as regions of reduced emission in EUV and X-ray wavelengths. They feature a characteristic open magnetic field configuration along which ionized electrons and atoms are accelerated into the interplanetary space. The resulting outflowing plasma is called high seed solar wind stream (HSS; see Cranmer 2009 and references therein). These HSSs are the major cause of minor to moderate geomagnetic activity at Earth (see Richardson 2018 and references therein).

To be able to predict the arrival and impact of those disturbances accurately, their origin and evolution need to be studied in detail. And to do so, it is imperative that CHs are accurately and reliably extracted, thus leading to the development of the Collection of Analysis Tools for Coronal Holes (CATCH). By using the intensity gradient across the CH boundary, it is possible to robustly extract CHs whose properties can then be analyzed. We find that the area of long-living CHs generally evolves by growing to a maximum before decaying. However, the associated magnetic field does not evolve equally. Depending on the CH, we find a correlation, an anti-correlation or even no correlation over the course of its lifetime. Therefore, we believe that the evolution of a CHs magnetic field is primarily driven by the large-scale connectivity changes in the Sun's global magnetic field. Further, we find that the plasma properties within CHs show a significant center to boundary gradient, which may justify the distance-to-boundary parameter used in some solar wind modeling.

To study the evolution of CHs in detail, a 360° view of the Sun is necessary; however, the magnetic far-side of the Sun still eludes. The few snapshots with Solar Orbiter provide only a fragmented picture of the magnetic field on the solar far-side. We found that by using EUV observations of the transition region (specifically using Stereo) it is possible to estimate the magnetic field density of CHs on the solar far side. In addition, we are currently investigating the incorporation of helioseismic observations into synoptic magnetograms to generate a maps that show the magnetic field of the whole Sun at a given time.

How to cite: Heinemann, S. G.: On the evolutionary aspects of solar coronal holes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8687, https://doi.org/10.5194/egusphere-egu23-8687, 2023.

Decades of observations have revealed that Coronal Mass Ejections (CMEs) come in a variety of forms. Some have a classic 3-part structure, whilst others can be fan shaped or jet-like. Some of these differences can be put down to projection effects, but differences in magnetic structure also play a key role. Observational and simulation studies are now highlighting that the path by which a CME flux rope traverses the solar corona, and in particular the magnetic structures it interacts with on the way, shape the ultimate characteristics of the CME further out in the heliosphere. Therefore, understanding the nature of CME flux rope interaction with the ambient corona is a key part of predicting their evolution through the heliosphere and ultimately their geoeffectiveness at Earth. In this talk I’ll discuss from a modelling perspective some recent efforts to understand this interaction process and what it tells us about CMEs on a range of scales.

How to cite: Wyper, P.: What impact does the pathway through the solar corona make on CMEs?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7312, https://doi.org/10.5194/egusphere-egu23-7312, 2023.

The problem of forecasting southward pointing magnetic fields in coronal mass ejections (CMEs) is closely tied to our ability to measure their magnetic field configuration between the Sun and 1 AU. I will review some of the ideas that have been developed to tackle this problem, from using solar proxies, heliospheric images, Faraday rotation and measuring the in situ magnetic field near the Sun Earth-line. Another way to make progress is to use the L1 data as boundary conditions for fast ensemble simulations, focusing on the flux rope parts inside CMEs. However, for any type of modeling and forecasting we need to better understand the global magnetic structure and shape of CME flux ropes from multi-spacecraft observations, now delivered by spacecraft such as Parker Solar Probe, Solar Orbiter, BepiColombo, STEREO-Ahead and Wind, ACE or DSCOVR. In the future, the PUNCH mission will allow for the first time to extract 3D information from heliospheric images, forming another trailblazer towards developing models for ESA's Vigil mission, and setting the stage for possible interplanetary fleets of small spacecraft.

How to cite: Möstl, C., Amerstorfer, U., Rüdisser, H. T., Weiss, A. J., Amerstorfer, T., Bauer, M., Davies, E. E., Bailey, R. L., and Reiss, M. A.: Forecasting southward pointing magnetic fields in solar coronal mass ejections, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7061, https://doi.org/10.5194/egusphere-egu23-7061, 2023.

Observations of the solar wind at the close to the Sun distances by the Parker Solar Probe (PSP) show most of the time very strongly variable solar wind plasma characteristics. Inspecting the PSP observations during first ten perihelion, together with this large variability, we have also found a significant number of intervals of enhanced solar wind velocity appearing simultaneously with the decrease of the solar wind density, which indicates that this solar wind is originating from the coronal holes. However, out of thirty such intervals only few of them show velocity above 500 km/s. Majority of the identified wind flows have velocity of only about 400 km/s indicating that this solar wind will not be clearly distinguished as a flow when observed at 1 au distances. Employing the magnetic connectivity tool (developed by ESA’s MADAWG group) to associate the solar wind observed by the PSP with their source regions on the Sun, we identified the sources of that enhanced solar wind observed by the PSP to be the small coronal holes.

In this study we present the characteristics of a solar wind flows originating from such small coronal holes at close to the Sun distances and compare them with the characteristics of the fast solar wind originating from the large coronal holes. We also discuss on the possible reasons why we do not find more intervals of the fast solar wind in the PSP observations and compare the characteristics of solar wind observed at close to the Sun distances and at 1 au.

How to cite: Magdalenic, J., Valliappan, S. P., and Rodriguez, L.: Solar wind originating from the small coronal holes , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9944, https://doi.org/10.5194/egusphere-egu23-9944, 2023.

Coronal mass ejections (CMEs) are the largest type of eruption seen on our Sun and the primary cause of geomagnetic disturbances and storms when they arrive at the Earth. Most geomagnetic storms are created by the impact of single CME yet in a significant fraction of cases they are caused by the interaction of multiple CMEs or CMEs with other transient phenomena. In this paper we implement a spheromak CME description within our 3-D heliospheric MHD model and self-consistently model their interactions with the pre-existing solar wind and with one another. We assess their geo-effectiveness at 1 AU through quantification of the relevant solar wind variables and an empirical measures based upon solar wind-magnetosphere coupling functions. We show how the orientation and handedness of a given CME can have a significant impact on its geoeffectivness due to a prolonged conservation of toroidal flux caused by differential interplay with the Parker Spiral, and how a large range of possible CME-CME interactions can produce a diverse range of geophysical impacts at the Earth.

How to cite: Desai, R., Koehn, G., Davies, E., Forsyth, R., Eastwood, J., and Poedts, S.: Successive interacting coronal mass ejections: Preconditioning, magnetic reconnection and flux erosion: How to create a perfect storm?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5740, https://doi.org/10.5194/egusphere-egu23-5740, 2023.

Our knowledge of the physical processes carrying information across Coronal Mass Ejections (CMEs), thereby controlling the way CME structures respond to external disturbances  in interplanetary space, is still incomplete. One prominent question is whether CMEs are “coherent” structures, i.e. potentially capable of responding in a uniform manner to external forces, and across what (macroscopic) spatial scales does such coherence exist. A necessary condition for different regions within a given CME to exhibit a coherent behavior is that they must be causally connected to the perturbation source. Past studies suggested interplanetary CMEs may behave as coherent structures only locally, and indicated that the spatial scale of coherence may be hampered by interactions with large-scale structures in the solar wind. Additionally, observational studies often assumed the correlation in the magnetic field profiles at different spacecraft locations as a proxy for coherence, but the physical link between correlation and coherence is still to be established. Characterizing the physical mechanisms mediating CME structural changes in different solar wind conditions at a fundamental level is therefore imperative to better understand their evolution and impact on space-borne and ground-based anthropic activities. 

In this study, we investigate the role of Alfvénic fluctuations (AFs) as mediators of coherence within interplanetary CMEs, and the physical relationship between correlation and coherence using multi-point observations near 1 au. In order to determine if and to what extent AFs alter CMEs at different spatial scales, we compare CME signatures at multiple spacecraft in terms of presence/absence of AFs, AF properties (if present), and correlation of magnetic signatures.  We contextualize the results in terms of the CME interaction history and the causal connection of different spacecraft observations. This study reveals how AFs affect the correlation of CME magnetic signatures across different spatial scales, and helps reconcile correlation scales within CMEs with their coherent behavior. 

How to cite: Scolini, C., Lugaz, N., Winslow, R., and Farrugia, C.: Multi-point Investigation of CME Alfvénicity and Coherence near 1 au, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7508, https://doi.org/10.5194/egusphere-egu23-7508, 2023.

Coronal Mass Ejections (CMEs) are the main drivers of interplanetary shocks and space weather disturbances. Strong CMEs directed towards Earth can have a severe impact on our planet and their timely prediction can enable us to mitigate (part of) the damage they cause. One of the key parameters that determine the geo-effectiveness of a CME is its internal magnetic configuration.

The novel heliospheric wind and CME propagation model Icarus (Verbeke et al. 2022) which is implemented within the framework of MPI-AMRVAC (Xia et al., 2018) introduces new capabilities for better and faster space weather forecasts. Advanced numerical techniques, such as solution adaptive mesh refinement (AMR) and radial grid stretching are implemented. The different refinement and coarsening conditions and thresholds are controlled by the user. These techniques result in optimized computer memory usage and a significant execution speed-up, which is crucial for forecasting purposes. 

In this study we validate a new magnetized CME model in Icarus by simulating  interplanetary coronal mass ejections (ICMEs).  We chose particular CME events observed at different radial distances from the Sun by MESSENGER and ACE. We aim to model two CME events, to examine the capabilities of the model in different configurations. We identify the originating active region for the CME of interest, reconstruct its characteristic parameters and initiate the CME propagation inside Icarus with a spheromak CME model. We focus on estimating the accuracy of the arrival time, the shock strength and the magnetic field components of the CME model in Icarus. Using observations of different satellites we can track the propagation of the CMEs in the heliospheric domain and assess the accuracy of the model at different locations.

Different AMR criteria are used to achieve higher spatial resolutions at propagating shock fronts and in the interiors of the ICMEs. This way the complex structure of the magnetic field and the deformation and (plasma and magnetic flux) erosion can be simulated with higher accuracy due to the advantage of AMR. Higher resolution is especially important for the spheromak model, because the internal magnetic field configuration affects the CME evolution and its interaction with the magnetized heliospheric wind significantly. We assess the capabilities of AMR at different locations in Icarus. Finally, the obtained synthetic time-series of plasma quantities at different satellite locations are compared to the available observational data. As a result, Icarus allows us to model CMEs with higher accuracy, yet efficiently.

TB acknowledges support from the European Union’s Horizon 2020 research and innovation program under No 870405 (EUHFORIA 2.0) and the ESA project “Heliospheric modeling techniques” (Contact No. 4000133080/20/NL/CRS).

How to cite: Baratashvili, T., Grison, B., Schmieder, B., and Poedts, S.: Validation of the magnetized ICME model with a multi-spacecradt study in Icarus, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3579, https://doi.org/10.5194/egusphere-egu23-3579, 2023.

Data-driven coronal models are attracting increasing attention for their ability to accurately capture the pre-eruption magnetic field configuration of active regions. However, the degree to which the current modelling techniques are able to provide information on the loss of stability and initial dynamics of the eruptions remains unclear. An interesting avenue for probing this is by employing time-dependent modelling such that the dynamic data-driving is switched-off at a given time. In this study, we investigate what we can learn from this relaxation procedure about the eruption itself and the instability that ultimately triggers it for at least two different active regions. To this effect, we use the time-dependent data-driven magnetofrictional model (TMFM) and perform multiple runs with varying relaxation times (i.e., time instances when the driving is switched off). Furthermore, we use two different physical models to simulate the coronal evolution after this point in time: the standard magnetofrictional method and a zero-beta MHD (magnetohydrodynamics) approach. In case of an eruption being triggered, the detailed evolution is characterised by tracking the associated magnetic flux rope which is extracted from the simulation data with a semi-automatic extraction algorithm. This flux rope detection and tracking procedure makes use of the twist number T_w, as well as the morphological gradient. For a further improvement of the extraction procedure, various mathematical morphology algorithms are performed to accurately extract the flux rope field lines. The properties of the extracted flux ropes are compared against their observational low-coronal manifestation in SDO/AIA data. 

How to cite: Wagner, A., Kilpua, E. K. J., Price, D. J., Pomoell, J., Poedts, S., Bourgeois, S., Kumari, A., Daei, F., and Sarkar, R.: Investigating Flux Rope Eruptivity via Time-dependent Data-driven Modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8506, https://doi.org/10.5194/egusphere-egu23-8506, 2023.

Coronal mass ejections (CMEs) interact with large-scale solar wind structures and other CMEs during their propagation in the heliosphere and undergo erosion, deflection, and deformation. In this work, we aim to quantify the erosion of the CMEs in different solar wind backgrounds using 3D MHD simulations. The EUropean Heliosphere FORecasting Information Asset (EUHFORIA; Pomoell and Poedts, 2018) is employed to create a relaxed solar wind background and evolve a CME on top of it between 0.1 au and 2 au. The LFF spheromak model is used to model the CME. Initially, we assume a simple dipolar background wind mimicking a solar minimum condition. CMEs with different geometric and magnetic field parameters (geometrical size, chirality, polarity, and magnetic flux) are evolved, and the evolution of the CME mass and the magnetic flux contained in the magnetic cloud is tracked to quantify mass and flux erosion. We also quantify the deformation of the CME during its evolution by parameterizing the separatrix surface of the magnetic cloud. The same experiment is repeated in the presence of a stream interaction region (SIR) interacting with the CME. We characterise the deformation of the different sides of the CME (with and without the interaction with SIR). In addition, we explore the adaptive mesh refinement and stretched grid features of the upgraded EUHFORIA heliospheric wind model, i.e., the newly developed ICARUS model (Verbeke et al., 2022) to resolve the CME shock and magnetic cloud and find the conditions to improve the modelling of the sheath region. Although the analysis of CME erosion has been carried out in 2.5D (axisymmetric) in previous works (Hosteaux et al., 2021), we explore the differences in 3D, which is required to fully quantify the erosion and deformation, and investigate their effect on the CME arrival time and geo-effectiveness at Earth.

How to cite: Maharana, A., Vanwalleghem, Y., Baratashvili, T., and Poedts, S.: Quantifying the effect of CME erosion on geo-effectiveness using EUHFORIA, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3444, https://doi.org/10.5194/egusphere-egu23-3444, 2023.

Coronal Mass Ejections~(CMEs) are extremely dynamical large scale events in which plasma-not only the coronal plasma-is ejected into the interplanetary space. Their interplanetary counterparts measured in-situ are Interplanetary Coronal Mass Ejections (ICMEs), which is also an important part of space weather.

Even though the kinetic properties of the plasma might change because of dynamic effects occurring during the expansion of the CME, the heavy ion characteristics remain unchanged after it leaves the low corona. Charge states of heavy ions reflect important information about the coronal temperature profile due to the freeze-in effect, while elemental abundances indicate potential source regions of the plasma.

With the help of the Pulse Height Analysis (PHA) data from the Solar Wind Ion Composition Spectromet (SWICS) on board the Advanced Composition Explorer (ACE), combined with a newly developed multi-population model, we are able to conduct a high time resolution (12 minutes) case study on a complex ejecta detected by ACE in May 2005. This case lasted more than 80 hours and caused a strong geomagnetic response, with a Dst index at -247.

Multiple discontinuous periods with highly charged heavy ions are identified, elemental abundances also differ during those ”hot” periods. Heavy ion characteristics provide us an unique opportunity to see the boundaries of different parts of an ICME.

How to cite: Gu, C., Heidrich-Meisner, V., and Wimmer-Schweingruber, R. F.: Variations of high time resolution heavy ion characteristics in the complex May 2005 ICME, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2841, https://doi.org/10.5194/egusphere-egu23-2841, 2023.

Coronal Mass Ejections (CMEs) carry large amounts of magnetized plasma into the heliosphere at very high speeds. Their interplanetary counterparts, or Interplanetary CMEs (ICMEs), create adverse space weather conditions around planets. These interplanetary structures have the potential to cause hazardous space weather and impact space- and ground-based technologies on Earth. At CESSI we have developed a 3D magnetohydrodynamic STORM Interaction (CESSI-STORMI) module to simulate the interactions between ICMEs and planets with and without a global magnetosphere. In this talk, I shall discuss our data-driven simulations to assess ICME impact on the Earth’s magnetosphere and  present a methodology to estimate their geo-effectiveness. We validate this module with observations and find a good match with the observed values of the Dst index for past events. In addition, we also present a qualitative study of the global magnetosphere under the influence of ICMEs. Our work allows us to estimate the severity of geomagnetic storms based on early, data-driven inputs of ICME flux rope profiles gleaned from near-Sun or in-situ observations. Thus our work has the potential to significantly extend the time window for predicting the severity of geomagnetic storms - which remains a grand challenge in heliophysics.

How to cite: Roy, S. and Nandy, D.: A magnetohydrodynamic modelling approach to simulate CME-forced planetary magnetospheres and predict geomagnetic impacts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16801, https://doi.org/10.5194/egusphere-egu23-16801, 2023.

Successful modeling of Coronal Mass Ejections (CMEs) is an important step towards accurately forecasting their space weather impact. Therefore, it is crucial to improve the various models, techniques and tools to reconstruct CMEs while validating simulations with observations of the solar corona and the inner heliosphere at various heliospheric distances with multi-viewpoint observations.

The Space Weather Modeling Framework (SWMF) includes MHD modeling of the solar wind and CMEs from the Sun to the Earth and beyond. The Alfven Wave Solar atmosphere Model (AWSoM) is a 3D extended-MHD solar corona model within SWMF that reproduces the solar wind background into which CMEs can propagate. The Eruptive Event Generator (EEG) module within SWMF is used to obtain flux-rope parameters to model realistic CMEs within AWSoM using different flux-rope configurations.

In this work supported by the NSF SWQU and LRAC programs, we use an ensemble of solar wind backgrounds to obtain the best solar wind plasma environments into which CMEs can be launched. We vary the flux-rope parameters within a fixed range and obtain an ensemble of CME simulations to match the model reconstructed results with remote coronagraph observations near the Sun (LASCO C2/C3 and STEREO COR1/COR2) as well as with in-situ observations of solar wind plasma at 1 au. The ensemble modeling is a step forward towards improving the accuracy of the tools that provide flux-rope parameter estimates as well as the uncertainty quantification of CME modeling.

How to cite: Sachdeva, N., Toth, G., Manchester, W., van der Holst, B., Jivani, A., and Chen, H.: Ensemble modeling of CMEs to reconstruct remote and in-situ observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8641, https://doi.org/10.5194/egusphere-egu23-8641, 2023.

Propagation of interplanetary (IP) shocks, particularly those driven by coronal mass ejections (CMEs), is still an outstanding question in heliophysics and space weather forecasting. Here we address effects of the ambient solar wind on the propagation of two CME-driven shocks from Sun to Earth. The two CME-driven shock events (CME03: April 3, 2010 and CME12: July 12, 2012) have the following properties: (1) driven by a halo CME (i.e., source location is near Sun-Earth line), (2) a southern hemispheric CME source location, (3) similar propagation speed (e.g., took ~2 days reach the Earth), (4) occurred in the non-quiet solar period, and (4) leading to a severe geomagnetic storm. What is interesting is that the initial (near the Sun) propagation speed, as measured by coronagraph images, of CME03 was slower (~300 km/s) than CME12, but it took about same time for both events to reach the Earth. According to in-situ solar wind observations from Wind, the CME03-driven shock was associated with a faster solar wind upstream of the shock than the CME12. This is also demonstrated in our global MHD simulations. This study emphasizes the importance of the background solar wind in the propagation of CME-driven shocks. Not only the initial propagation speed near the Sun but also the ambient solar wind speed is the key to timing the arrival of CME events. The present study also demonstrated that global MHD simulations with realistic solar wind inputs is able to precisely predict the arrival of CME events.

How to cite: Wu, C.-C., Liou, K., wood, B., and Hutting, L.: Effects of background solar wind on the propagation of coronal mass ejection driven shock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7390, https://doi.org/10.5194/egusphere-egu23-7390, 2023.

It is widely known that the fast solar wind originates mainly from coronal holes (CHs) in the solar corona. Associations between the CH characteristics and the properties of the fast solar wind in situ have been studied throughout the years from different authors leading to diverse degrees of correlation (Nolte et al. 1976; Vršnak et al. 2007; Karachik et al. 2011; Rotter et al. 2012a; Hofmeister et al. 2018; Heinemann et al. 2020). In this work, we introduce and quantify the geometrical complexity of CHs, a parameter that has been neglected so far in similar studies. For a particular CH sample, we explore how complexity affects the peak speed of the fast solar wind at Earth and its association with other CH properties. We further compare observations of fast solar wind at Earth with forecasts from EUHFORIA. We evaluate our results, and present the efforts and restrictions we encounter towards improving our prediction capabilities by exploiting recent PSP observations.

How to cite: Samara, E., Magdalenic, J., Rodriguez, L., Poedts, S., Georgoulis, M. K., Pinto, R. F., Arge, C. N., Heinemann, S. G., and Hofmeister, S. J.: The fast component of the solar wind: origins, correlations and modeling with EUHFORIA, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9486, https://doi.org/10.5194/egusphere-egu23-9486, 2023.