Session SWR2 - Interplanetary Coronal Mass Ejections and Solar Energetic Particles
Camilla Scolini, onsite (University of New Hampshire, USA), Luciano Rodriguez, onsite (Royal Observatory of Belgium, Belgium), Sergio Dasso (Universidad de Buenos Aires, Argentina)
Coronal mass ejections (CMEs) and their interplanetary counterparts (ICMEs) are of key interest in the field of solar-terrestrial relations. They are among the largest and most energetic transients in the heliosphere, and are main drivers of the most intense geomagnetic storms. CMEs and ICMEs can generate shock waves, even very low in the solar corona, producing significant fluxes of solar energetic particles (SEPs). They are also important drivers of relativistic electron enhancements in the radiation belts surrounding the Earth. Solar flares associated with CME eruptions can in turn have important impacts (UV radiation, particles) on the Earth's atmosphere. There is thus a strong need for realistic data-driven simulations of CMEs/ICMEs and their associated shocks and particle environment using a variety of theoretical, physics-based and semi-empirical models. Additionally, models can be complemented with the use of data from novel missions such as Parker Solar Probe and Solar Orbiter, wide-field heliospheric observations such as those provided by the STEREO mission, and enhanced catalogues such as HELCATS. In this session, we invite observational, theoretical, and modelling contributions on ICME-related topics, including ICME propagation in the heliosphere, the interaction of ICMEs with Earth and/or other planets, the link between CMEs and ICMEs, the generation and transport of SEPs by CME-driven shocks, and the forecasting of ICME and SEP occurrence and characteristics.
Poster ViewingMonday October 24, 09:00 - 14:00, Poster Area Talks Monday October 24, 13:45 - 15:00, Water Hall Monday October 24, 16:00 - 17:00, Water Hall Tuesday October 25, 13:30 - 14:45, Water Hall Click here to toggle abstract display in the schedule
Talks : Time scheduleMonday October 24, 13:45 - 15:00, Water Hall| 13:45 | Predicting the Bz magnetic field component in solar coronal mass ejections | Moestl, C et al. | Oral | | | C. Möstl [1], A. J. Weiss [1,2], R. L. Bailey [3], M. A. Reiss [4,5], T. Amerstorfer [1,5], U.V. Amerstorfer [1], M. Bauer [1], H. T. Rüdisser [1], D. Barnes [6], J. A. Davies [6], R. A. Harrison [6], R. Laker [7], T. Horbury [7], D. Heyner [8], S. Bale [9] | | | [1] Austrian Space Weather Office, Zentralanstalt für Meteorologie und Geodynamik, Graz, Austria, [2] Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, USA, [3] Conrad Observatory, Zentralanstalt für Meteorologie und Geodynamik, Graz, Austria, [4] Community Coordinated Modeling Center, Code 674, NASA GSFC, Greenbelt, MD 20771, USA, [5] Space Research Institute, Austrian Academy of Sciences, Graz, Austria, [6] RAL Space, Rutherford Appleton Laboratory, Harwell Campus, Didcot, UK, [7] Department of Physics, Imperial College London, London, UK, [8] Technical University of Braunschweig, Braunschweig, Germany, [9] Physics Department and Space Sciences Laboratory, University of California, Berkeley, CA, USA | | | I will present an overview of some recent advances concerning the "Bz problem“ in space weather forecasting, which consists in predicting the north-south magnetic field component at the Sun-Earth L1 point. The Bz field, together with the solar wind speed, determines geomagnetic storm strength. One 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. As a pre-requisite we need to better understand the global magnetic structure and shape of CME flux ropes and shocks from multi-spaceraft observations. By combining the in situ and remote sensing data from Solar Orbiter, Parker Solar Probe (PSP), BepiColombo, STEREO-Ahead and SOHO, ACE, Wind and DSCOVR we are now in a great position to make progress, given that solar activity is on the rise. In March 2022, the Solar Orbiter MAG instrument detected a CME event at 0.43 AU, allowing to forecast its Bz behavior at 1 AU near Earth in real time, showing the potential for solar wind monitors closer to the Sun that temporarily cross the Sun-Earth line for Bz forecasts. In the longterm, the goal is to regularly anticipate flux rope chirality, orientation and field strength from remote images. The upcoming 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.
| | 14:00 | Influence of the coronal mass ejection orientation on its propagation | Martinic, K et al. | Oral | | | Karmen Martinic [1], Mateja Dumbovic [1], Manuela Temmer [2], Astrid Veronig [2,3], Bojan Vršnak [1] | | | [1] Hvar Observatory, Faculty of Geodesy, University of Zagreb, Zagreb, Croatia, [2] Institute of Physics, University of Graz, Graz, Austria, [3] Kanzelhöhe Observatory for Solar and Environmental Research, University of Graz, Graz, Austria | | |
Configuration of the interplanetary magnetic field and related ambient solar wind features in the ecliptic and meridional planes are different. Therefore, one can expect that the coronal mass ejection (CME) inclination influences the propagation of the CME itself. This study aims to investigate the non-radial flow in the sheath region of the interplanetary CME (ICME) in order to provide the first proxy to relate the ICME orientation with its propagation. We investigated isolated CME-ICME events from the period 1997-2018. We obtained the CME tilt in the “near-Sun” environment by performing the ellipse fitting technique to the CME outer front as determined from the SOHO/LASCO coronagraph. In the “near-Earth” environment, we obtained the orientation of the corresponding ICME using in-situ plasma and field data and we investigated the non-radial flow in its sheath region. Most of the CME-ICME pairs under investigation were found to be characterized by a low inclination. For the majority of CME-ICME pairs, we obtain consistent estimations of the dominant inclination from remote and in situ data. The observed non-radial flows in the sheath region show a greater y-direction to z-direction flow ratio for high-inclination events, indicating that the CME orientation could have an impact on the CME propagation.
| | 14:15 | Estimating the magnetic vextors of ICMEs observed by radially aligned multiple spacecraft using INFROS model | Srivastava, N et al. | Oral | | | Nandita Srivastava[1], Ranadeep Sarkar[2], Emilia Kilpua[3] | | | [1]Udaipur Solar Observatory, Udaipur, India; [2]University in Helsinki, Finland | | | We have developed the Interplanetary flux rope simulator (INFROS) which is an observationally constrained analytical model dedicated for forecasting the strength of southward component (Bz) of magnetic field embedded in interplanetary coronal mass ejections (ICMEs). We validate the model for specific ICMEs which were sequentially observed by the radially aligned multiple spacecraft at two different heliocentric distances. The selected ICMEs events in this study include isolated ICMEs as well as those that include the interaction of the ICMEs with the high-speed streams (HSS) and high- density streams (HDS).
Our analysis reveals that For the isolated CMEs, the INFROS model output matches well with the in-situ observations. On the other hand, for the interacting CMEs, although the model is able to capture the CME evolution at the first spacecraft until the interaction occurs, however it under-estimates the field strength at the second spacecraft. This may be explained by the fact that the ICME evolution ceases to be self-similar due to its interaction with the HSS and HDS. Our results clearly demonstrate that INFROS model can be used as an efficient tool to forecast the magnetic vectors of ICMEs for the cases of isolated CMEs. We further conclude that the assumption of self-similar expansion provides the lower limit for the magnetic field strength estimated at any heliocentric distance, based on the remote sensing observations. | | 14:30 | Propagation of a magnetised ICME in minimum and maximum of solar activity | Perri, B et al. | Oral | | | Barbara Perri [1,2], Brigitte Schmieder [1,3], Pascal Démoulin [3], Stefaan Poedts [1,4] | | | [1] CMPA, KU Leuven, Leuven, Belgium [2] DAP, CEA AIM, Université Paris-Saclay, France [3] LESIA, Observatoire de Paris, Meudon, France [4] Institute of Physics, University of Maria Curie-Sklodowska, Lublin, Poland | | | The propagation of ICMEs in the heliosphere is influenced by a great number of physical phenomena, related both to the internal structure of the ICME but also to its interaction with the ambient solar wind and heliospheric current sheet. The understanding of such phenomena is crucial to be able to improve numerical modelling and provide better space weather forecasts for the time of arrival of perturbations at Earth. As individual structures of the solar wind such as helmet streamers of high-speed streams have begun to be discussed, the influence of the long-term variability of solar activity on transient events is still not clear. Indeed, the solar magnetic field is modulated by the 11-year dynamo cycle generated inside the Sun, and then affecting the entire heliosphere structure by means of the Parker spiral and its shaping of the solar corona. We know that there are more transient events at maximum of activity and that they are usually more intense, but the exact influence of solar activity on their propagation remains to be discussed. It is becoming even more important to assess these differences as solar cycle 25 is rising, and thus many models calibrated on the minimum of activity between cycles 24 and 25 may become less accurate.
We perform a theoretical study to try to answer these questions. We select two realistic background wind environments: the first corresponds a very quiet minimum of activity in December 2008, the other one to a maximum of activity during a solar eclipse as seen form Earth in March 2015. We then use the heliospheric propagator EUHFORIA to inject the same CME in those two backgrounds and quantify the differences. We use several models for the CME to study different interactions (cone for hydrodynamic, spheromak for magnetic). We also define what is an average CME at 0.1 AU, using both observations and numerical simulations, to have a representative statistical case. We explain how the flows and magnetic structures impact the propagation of the ICME towards Earth. We especially discuss the impact of the chirality of the ICME with respect to the heliospheric current sheet, and its consequence for geo-effectiveness.
This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No.~870405 (EUHFORIA 2.0) and the ESA project "Heliospheric modelling techniques“ (Contract No. 4000133080/20/NL/CRS). | | 14:45 | Refined halo CME forecast | Yordanova, E et al. | Oral | | | Emiliya Yordanova [1], Mateja Dumbović [2], Manuela Temmer [3], Camilla Scolini [4,5], Evangelos Paouris [6,7], Elisabeth Werner [1] and Andrew P. Dimmock [1] | | | [1]Swedish Institute of Space Physics, Uppsala, Sweden, [2] Hvar Observatory, Faculty of Geodesy, University of Zagreb, Croatia, [3] Institute of Physics, University of Graz, Graz, Austria, [4] University of New Hampshire, NH, USA, [5] University Corporation for Atmospheric Research, Boulder, CO, USA, [6] George Mason University, Fairfax, VA 22030, USA, [7] Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723, USA | | | Earth-directed halo coronal mass ejections (CMEs) can drive intense geomagnetic storms. The forecast of their arrival time at L1 is prone to large errors, because 1) the estimation of halo CMEs’ kinematics is difficult due to projection effects in plane-of-sky, and 2) their propagation can be greatly affected by the state of the plasma in the lower corona and the one of the ambient solar wind in which the CMEs evolves on-route to Earth. In this study, we have used a unified set of twelve halo CMEs from solar cycle 24 with similar characteristics: large initial speeds (> 1000 km/s) and wide half-angles; source region in the central area of the solar disk; and high geoeffectivity. We have modeled the propagation of the CMEs using four different models – Drag-Based Model (DBM), Effective Acceleration Model (EAM), EUropean Heliospheric Forecasting Information Asset (EUHFORIA) and ENLIL. The same CME parameters have been used in all models and the resulting predictions of the time of arrival and impact speed have been compared with the observations at L1. The performance assessment of the different models has been based on the application of the same metrics. Furthermore, we have applied a refined input to the models taking into account the properties of the background solar wind which lead to improved forecast in both CME arrival time and impact speed. |
Monday October 24, 16:00 - 17:00, Water Hall| 16:00 | Spheromak tilting and drifting in the context of coronal mass ejection reconstruction | Asvestari, E et al. | Oral | | | Eleanna Asvestari[1], Tobias Rindlisbacher[2], Jens Pomoell[1], Emilia Kilpua[1], Ranadeep Sarkar[1] | | | [1] Faculty of Science, Department of Physics, University of Helsinki, Finland, [2] Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Switzerland | | | In recent efforts to achieve more accurate space weather predictions, spheromaks have been employed to model coronal mass ejections as magnetised structures. The spheromak is an axisymmetric, force-free configuration within which plasma is confined by a twisted magnetic field that fills a spherical volume. When the magnetic moment of a spheromak is at an angle with the ambient magnetic field in which it is inserted, then the structure experiences a torque, causing it to tilt – rotate – to reduce its magnetic potential energy. The result of the tilting is a change in the spheromak’s orientation, compared to how it was inserted. In addition, the spheromak can also experience a magnetic net-force, which causes it to undergo additional drift. Tilt and drift are sensitive to the initial conditions for spheromak and ambient solar wind, which can have implications when comparing the model output to observations. In our study, using the EUHFORIA space weather model, we investigate in detail the physics behind the spheromak tilting and its dependency on the spheromak input parameters and the properties of the ambient magnetic field. This is done by utilizing geometric, magnetic, and thermodynamic characteristics of spheromak structures to automatically monitor their position and orientation. In all cases considered in our study the spheromak has undergone rotation and often ended up with a significantly different orientation compared to the one it had during insertion. It is, therefore, crucial to take this phenomenon into consideration when comparing model output to observations. | | 16:15 | On the role of spheromak density to mitigate its rotation effect in global MHD models for space weather forecasting | Sarkar, R et al. | Oral | | | Ranadeep Sarkar [1], Jens Pomoell [1], Emilia Kilpua [1], Eleanna Asvestari [1], Nicolas Wijsen [2], Anwesha Maharana [2], Stefaan Poedts [2] | | | [1] University of Helsinki, Department of Physics, Helsinki, Finland [2] KU Leuven, Belgium | | | One of the major challenges in space weather forecasting is to reliably predict the north-south magnetic field component (Bz) of interplanetary coronal mass ejections (ICMEs) at near-Earth space. Utilizing the state-of-the art global heliospheric MHD models that widely use the spheromaks to characterize the magnetic structure of a CME, several efforts have been made to simulate the CME magnetic field from Sun-to-Earth. However, the recent studies (Asvestari et al. 2021) have reported that the spheromak tends to rotate due to its interaction with the ambient medium, resulting in a large uncertainty in modelling the magnetic vectors of a ICME at 1 AU.
In this work, we study the spheromak rotation and its dependence on the initial density, by modelling a 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 at the front as compared to the low-density ones. Using the higher order density values, we find that the uncertainty in Bz prediction significantly reduces in absence of any large rotation of the spheromak.
This research has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 870405 (EUHFORIA 2.0). | | 16:30 | Propagation of a flux rope in the coronal model COCONUT | Linan, L et al. | Oral | | | Luis Linan[1], Florian Regnault[2], Barbara Perri[1], Michaela Brchnelova[1], Blazej Kuzma[1], Andrea Lani[3], Stefaan Poedts[1][4] | | | [1]Centre for mathematical Plasma Astrophysics, KU Leuven, Leuven, Belgium, [2]Space Science Center, University of New Hampshire, Durham, New Hampshire, United States, [3]Von Karman Institude For Fluid Dynamics, Brussels, Belgium, [4]Institute of Physics, University of Maria Curie-Sklodowska, Lublin, Poland | | | The EUropean Heliosphere FORecasting Information Asset (EUHFORIA) is an innovative tool for space weather predictions. EUHFORIA is divided into two parts : a semi-empirical coronal model currently used to create the boundary conditions for the background solar wind, and a magnetohydrodynamics (MHD) heliospheric model. The Coronal Mass Ejections (CMEs) are injected at 0.1 AU and therefore are not connected to their source of emission. To go beyond this limitation, currently being used model will be replaced by a full magnetohydrodynamic coronal model called COCONUT (COolfluid COroNal UnsTructured). Within COCONUT, we insert a magnetic flux rope following the modified Titov-Démoulin model (TDm) flux rope and track its propagation from the solar surface to 0.1 AU. Hence, within the realistic corona configuration reconstructed by COCONUT from the GONG magnetic map of the 1st of August 2008, we study the evolution of the TDm flux rope with different initial geometrical and physical parameters. In addition, we anchor the torus at different locations to determine how the surrounding field affects the propagation. We found that our results reflect dynamic expected by the standard flare model with features such as presence of post-flare loops and the pinching of the CME's legs. We have also highlighted that the more the system is initially unstable, the more important and faster its radial expansion is. All these results are consistent with those obtained by following the evolution of the same flux rope in the dipolar magnetic field of the coronal PLUTO model. Once reached 0.1 AU, the thermodynamic and magnetic properties of our CME will be used as initial condition for the 3D time-dependent ideal MHD heliospheric domain of EUFHORIA in order to quantify its potential geo-effectiveness at Earth. | | 16:45 | Global MHD simulations of solar wind structures in the inner heliosphere | Wu, C et al. | Oral | | | Chin-Chun Wu[1], Kan Liou[2], Brian E. Wood[1] | | | [1]Naval Research Laboratory, Washington, DC 20375, USA; [2]Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland, USA | | | The global three-dimensional (3-D), time-dependent, magnetohydrodynamic (MHD) simulation model (G3DMHD; Wu et al. 2020, Solar Physics) is an alternative to the Enlil and many other physics-based models for studying solar wind dynamics in the inner heliosphere and for space weather forecasting. Here we will present current capability of the G3DMHD by presenting some of our recent simulation results on the time profiles of the solar wind structures at 1 AU. These structures include the heliospheric current sheet (HCS), co-rotation interaction region (CIR), interplanetary coronal mass ejection (ICME) and its driven shock, and slow/fast solar wind. We will pay particular attention on the dynamics of ICME-driven shocks and their interac-tion with the HCS. We will also discuss the performance of our model and directions for future developments. |
Tuesday October 25, 13:30 - 14:45, Water Hall| 13:30 | Energetic electron event on October 9, 2021 observed by Solar Orbiter | Jebaraj, I et al. | Oral | | | Immanuel. C. Jebaraj[1,2], Athanasios Kouloumvakos[3], Nina Dresing[4], Alexander Warmuth[5], Jan Gieseler[4], Christian Palmroos[4], Thomas Wiegelmann[6], Nicolas Wijsen[2], Jens Pomoell[7], Vratislav Krupar[8,9], Jasmina Magdalenic[1,2], Rami Vainio[4] | | | [1]Solar–Terrestrial Centre of Excellence—SIDC, Royal Observatory of Belgium, 1180 Brussels, Belgium; [2]Center for mathematical Plasma Astrophysics-CmPA, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium; [3]The Johns Hopkins University Applied Physics Laboratory, 11101 Johns Hopkins Road, Laurel, MD 20723, USA; [4]Department of Physics and Astronomy, University of Turku, Finland; [5]Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany; [6]Max-Planck-Institut fur Sonnensystemforschung, Max-Planck-Strasse 2, 37191 Katlenburg-Lindau, Germany; [7]Department of Physics, University of Helsinki, Finland; [8]Goddard Planetary Heliophysics Institute, University of Maryland, Baltimore County, Baltimore, MD 21250, USA; [9]Heliospheric Physics Laboratory, Heliophysics Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA | | | Solar eruptive events, such as flares and coronal mass ejections (CMEs) can drive shock waves, and accelerate particles to energies ranging from a few tens of keVs to several GeVs. The origin of solar energetic particles (SEPs) measured in-situ has been a long-standing debate, mainly due to the difficulty in distinguishing between several possible mechanisms of particle acceleration. Especially, in the case of high energy electrons, the role of shock waves is not yet fully understood.
We study the solar energetic particle (SEP) event observed on October 9, 2021, by multiple spacecraft including Solar Orbiter (SolO). The event was associated with an M3.7 flare, a coronal mass ejection (CME) and a shock wave. During the event, high-energy protons and electrons were recorded by multiple instruments located within a narrow longitudinal wedge. An interesting aspect of the event was the multi-stage particle energization during the flare impulsive phase and also what appears to be a separate phase of electron acceleration detected at SolO after the flare maximum.
We utilize SEP electron observations from the Energetic Particle Detector (EPD) and hard X-ray (HXR) observations from the Spectrometer/Telescope for Imaging X-rays (STIX) on-board SolO, in combination with radio observations at a broad frequency range. We focus on establishing an association between the energetic electrons and the different HXR and radio emissions associated with the multiple acceleration episodes.
Our first results show that the flare was able to accelerate electrons for at least 20 minutes during the non-thermal phase observed in the form of five discrete HXR pulses. We also show evidence which points at the possibility of the shock wave accelerating electrons during and after the impulsive flare phase. The detailed analysis of EPD electron data shows that there was a time difference in the release of low- and high-energy electrons and also that the electron anisotropy characteristics were different during the separate phases of electron energization.
| | 13:45 | Simulating the gradual SEP event of 15 March 2013 with PARADISE | Niemela, A et al. | Oral | | | Antonio Niemela [1], Nicolas Wijsen[1], Angels Aran [3], Luciano Rodriguez[2], Jasmina Magdalenic[1,2], Stefaan Poedts[1,4] | | | [1]Centre for mathematical Plasma Astrophysics, Dept. of Mathematics, KU Leuven, Belgium. [2]Solar-Terrestrial Centre of Excellence—SIDC, Royal Observatory of Belgium, Belgium [3]Departament d$'$Astronomia i Meteorologia, Facultat de Física, Universitat de Barcelona, Spain.[4]Institute of Physics, University of Maria Curie-Skłodowska, Poland | | | In this work, we model the gradual solar energetic particle (SEP) event that was observed by near-Earth spacecraft on March 15, 2013. We employed the PARADISE model (PArticle Radiation Asset Directed at Interplanetary Space Exploration), which simulates the transport of SEPs through non-nominal solar wind configurations generated by the magnetohydrodynamic (MHD) model EUHFORIA (EUropean Heliospheric FOrecast Information Asset).
This gradual SEP event starts with a long duration GOES M 1.1 X-ray flare originating from the NOAA active region 11692 and with peak intensity registered at 06:58 UT. The M-class flare was associated with the earth-directed asymmetric halo CME that erupted from the Sun at 07:12UT (as seen by the coronagraphs aboard SOHO and STEREO). The halo CME was preceded by few slower and narrower CMEs. On March 16, the particle counts at L1 started increasing. A first sudden increase was registered, for energies up to 80 MeV, at around 20:00 UT and almost 6 hours after, the bulk of the particles arrived and the flux remained enhanced until the ICME ended on March 17, at around 06:00 UT.
The several CMEs that occurred in the days prior to the solar eruption of March 15 disturbed the solar wind. Such disturbed conditions may have affected the interplanetary transport of the SEPs, potentially explaining the delayed onset of the SEP event at Earth. In this work we aim to show that the SEP forecasting strongly depends on the background solar wind estimation by presenting results at different virtual spacecraft, with different connectivity to the sources of particles.
We acknowledge 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)
| | 14:00 | Modelling the early acceleration of SEPs with STAT and multi-spacecraft validation | Palmerio, E et al. | Oral | | | Erika Palmerio[1], Jon Linker[1], Ronald Caplan[1], Matthew Young[2], Nathan Schwadron[2], Tibor Török[1], Cooper Downs[1], Christina Cohen[3] | | | [1]Predictive Science Inc., San Diego, CA, USA, [2]University of New Hampshire, Durham, NH, USA, [3] California Institute of Technology, Pasadena, CA, USA | | | Large solar energetic particle (SEP) events are usually associated with strong eruptions that produce fast coronal mass ejections (CMEs). The early acceleration phase of SEPs is believed to take place at solar flare sites and/or at the shock fronts driven by fast CMEs in the low corona (at heights of a couple of solar radii). There are numerous examples of SEP events that are observed over broad longitudes across the heliosphere, thus showing that—at least in some cases—shock–observer connectivity alone cannot explain the wide distribution of enhanced particle fluxes that is observed. In this presentation, we show modelling results of widespread SEP events with the Solar Particle Event (SPE) Threat Assessment Tool (STAT) model, which combines the Magnetohydrodynamic Algorithm outside a Sphere (MAS) CME code with the Energetic Particle Radiation Environment Model (EPREM) that uses the focussed transport equation to simulate the early phase of SEP events. We also validate the resulting particle fluxes at different points throughout the inner heliosphere with multi-spacecraft data, including measurements from more recent missions such as Parker Solar Probe and Solar Orbiter. | | 14:15 | Relationship Between Proton Flux Fluence Spectra at L1 and Selected Parameters of Associated ICMEs and Forbush Decreases | Savić, M et al. | Oral | | | Mihailo Savić, Nikola Veselinović, Aleksandar Dragić, Dimitrije Maletić, Dejan Joković, Vladimir Udovičić, Radomir Banjanac, David Knežević | | | Institute of Physics Belgrade | | | By combining in-situ measurements by space borne instruments with ground-based cosmic ray observations, we investigate the relationship between proton flux measured at L1, selected solar activity indices, and intensity measurements of cosmic rays during transient decreases of cosmic ray intensity, also known as Forbush decreases. We present cross-correlation study done using proton flux data from SOHO/ERNE instrument, as well as data collected by world-wide network of neutron monitor detectors, during some of the strongest Forbush decreases over the last two completed solar cycles. We fitted in-situ measured protons fluence spectra with double power law and used power exponents from these fits to parameterize the shape of fluence spectra. Through correlative analysis, we have demonstrated the connection between the shape of proton fluence spectra and several interplanetary coronal mass ejection and Forbush decrease parameters. We discuss the possibility of these power exponents to be used as valuable new parameters in future studies of mentioned phenomena, especially in the case of strong Forbush decreases. | | 14:30 | An upgrade of the ESPERTA forecast model for Solar Proton Events through machine learning | Laurenza, M et al. | Oral | | | Laurenza Monica[1], Stumpo Mirko[1,2], Benella Simone[1], Alberti Tommaso[1]; Consolini Giuseppe[1], Marcucci Maria Federica[1] | | | [1]Institute of Space Astrophysics and Planetology - INAF, Via del Fosso del Cavaliere, 00133 Rome, Italy; [2]Department of Physics, University of Rome Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Rome, Italy | | | Several techniques have been developed in the last two decades to forecast Solar Proton Events (SPEs), mainly based on the statistical association between the >10 MeV proton flux and precursor parameters. Among them, the Empirical model for Solar Proton Events Real Time Alert (ESPERTA) provides a timely prediction for the occurrence of SPEs (>10MeV proton flux ≥10 pfu), typically addressed by such techniques, as well as additional prediction for the more geoeffective SPEs which have a >10 MeV flux threshold of 100 pfu. Here, we upgrade the ESPERTA model by applying a novel machine learning algorithm to flare-based parameters to provide early warnings of SPE occurrence together with a fine-tuned radiation storm level. Moreover, we perform a validation by using different metrics over flare and SPE data the last two solar cycles and discuss the performance of the method. |
Posters| 1 | Investigating residual Magnetosheath Jets during Coronal Mass Ejections | Koller, F et al. | Poster | | | Florian Koller [1], Ferdinand Plaschke [2], Luis Preisser [3], Manuela Temmer [1], Owen W. Roberts [3], Stefan Weiss [1], Zoltan Vörös [3] [4] | | | [1] Institute of Physics, University of Graz, Austria [2] Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Germany [3] Space Research Institute, Austrian Academy of Sciences, Graz, Austria [4] Institute of Earth Physics and Space Science, ELRN, Sopron, Hungary | | | The terrestrial magnetosheath consist of shocked and turbulent solar wind (SW) plasma. Dynamic pressure enhancements are frequently observed within this region. We call these enhancements magnetosheath jets. They travel anti-sunward from the bow shock to the Earth’s magnetopause, where they can be geoeffective. Jets can cause reconnection after impacting the magnetopause and they can also trigger substorms. They therefore constitute a significant coupling effect between the solar wind and the magnetosphere of the Earth. The majority of jets are linked to processes at the quasi-parallel bow shock and the foreshock. We analyze, how these jets are related to large-scale SW structures, in particular coronal mass ejections (CMEs). In our analysis we use jets detected by the THEMIS spacecraft as well as OMNI SW data between 2008 and 2021. A recent study showed that the number of detected jets is lowered during the passing of CMEs compared to quiet SW times. We find that jets are unlikely to appear during simultaneous occurrences of low Alfvénic Mach numbers and high IMF cone angles, which are SW conditions often found during CMEs and their associated sheaths. These conditions may inhibit the formation of a well-defined foreshock and therefore negatively affecting the jet generation. We analyze the differences between jets and the jet origin mechanisms during CMEs compared to jets during quiet solar wind times. | | 2 | Differences of Forbush decreases produced by ICMEs and SIRs | Dasso, S et al. | Poster | | | Sergio Dasso[1,2], Gutierrez Christian [1,2] | | | [1]Instituto de Astronomía y Física del Espacio (IAFE) - CONICET - UBA - Argentina; [2]Departamento de Ciencias de la Atmósfera y los Océanos (DCAO) - FCEN - UBA - Argentina. | | | The transport of galactic cosmic rays (GCRs) in the heliosphere depends on the interplanetary conditions. Interplanetary coronal mass ejections (ICMEs) and stream interaction regions (SIRs) are the two major solar wind transient structures, causing severe GCRs transport distortions and causing Forbush decreases (FDs). In this study we analyze a set of ICMEs and SIRs occurred in the period 1998-2017 and their consequences on the GCR flux measured by neutron monitors at MC Murdo, located at the Antarctica. In particular, we focus the study on the main differences between FDs produced by ICMEs and SIRs, using a Superposed Epoch Analysis (SEA) to obtain typical FD profiles produced by both structures, distinguishing different sub-structures. | | 3 | Drag-based kinematics of ICMEs: the impact of virtual mass and magnetic erosion and towards application to real events | Stamkos, S et al. | Poster | | | Sotiris Stamkos[1], Spiros Patsourakos[1], Angelos Vourlidas[2], Ioannis Daglis[3] | | | [1]University of Ioannina; [2]Johns Hopkins University; [3]National and Kapodistrian University of Athens | | | To improve our understanding of the dynamic interactions of Interplanetary Coronal Mass Ejections (ICMEs) with the ambient solar wind and interplanetary magnetic field, we investigate the impact of magnetic erosion on the aerodynamic drag force acting on fast ICMEs. In particular, we first develop empirical equations for the basic physical parameters of non-eroded ICMEs, assuming a cylindrical morphology. Furthermore, we examine the impact of the virtual mass on the equation of motion by essentially studying a variable mass system. We quantify the effect of the magnetic reconnection process, which erodes part of the structure's azimuthal magnetic flux and outer-shell mass, on the drag acting on ICMEs and determine its impact on the time and speed of arrival of those transients at 1 AU. Ultimately, we describe our first steps towards implementing our model in a "real" ICME subject to magnetic erosion, aiming to compare its kinematics with and without erosion. | | 4 | On the magnetosheath jet production during a CME passage: A case study | Preisser, L et al. | Poster | | | L. Preisser[1], F. Plaschke[2], F. Koller[2], M. Temmer[3], O. Roberts[1], Z. Vörös[1] | | | [1]Space Research Institute/Austrian Academy of Sciences, Graz, Austria. [2]Institut für Geophysik und extraterrestrische Physik, TU Braunschweig, Germany. [3]Institute of Physics, University of Graz, Austria | | | Jets are localized enhancements in dynamic pressure observed through the Earth’s magnetosheath (EMS), being able to impact the magnetopause. Consequently, jets can be geoeffective depending on the amount of mass, momentum and the energy they transport. Coronal Mass Ejections (CMEs) by the other hand are large scale solar wind events considered that are the main driver of severe geomagnetic activity and space weather phenomena.
As the CME crosses the EMS, its structure (upstream side - shock - sheath - magnetic ejecta) changes the magnetosheath environment. How these changes in the EMS region affect the production of jets is a topic just recently explored by Koller et al. 2021. Based on this recent statistical work we characterize the jets observed by THEMIS spacecraft during the passage of a CME. Comparing WIND and THEMIS data, we discuss how these differences can be associated with different jet generation mechanisms as a consequence of the passage of the CME and how the different characteristics of the jets observed as each part of the CME crosses the Earth's magnetosheath are in accordance with the statistical study by Koller et al. 2021.
| | 5 | Scales of Magnetic Complexity and Coherence within ICMEs: Insights from Spacecraft Swarms in Global Heliospheric Simulations | Scolini, C et al. | Poster | | | Camilla Scolini[1,2], Réka M. Winslow[1], Noé Lugaz[1], Stefaan Poedts[2,3] | | | [1] Space Science Center, University of New Hampshire, Durham, NH, USA, [2] University Corporation for Atmospheric Research, Boulder, CO, USA, [3] Centre for mathematical Plasma Astrophysics, KU Leuven, Leuven, Belgium, [4] Institute of Physics, University of Maria Curie-Skłodowska, Lublin, Poland | | | Many aspects of the three-dimensional (3-D) structure and evolution of Interplanetary Coronal Mass Ejections (ICMEs) remain unexplained. A prominent open question is whether they are magnetically-coherent objects, and at which scales such coherence exists. Recent studies also highlighted the ever-changing nature of their magnetic complexity during propagation, primarily as a consequence of interactions with other large-scale solar wind structures. Yet, no comprehensive investigation on the spatial distribution of magnetic complexity and its evolution with heliocentric distance has been attempted. Pursuing a novel approach, in this work we perform numerical simulations using the EUHFORIA heliospheric model, and exploit its 3-D capabilities to address the following questions: (1) What is the spatial distribution of magnetic complexity within ICME flux ropes? (2) Across what spatial scales might ICME flux ropes behave as magnetically coherent objects? (3) How do complexity and coherence depend on the heliocentric distance and the specific evolution history of an ICME flux rope? We simulate ICMEs interacting with different solar winds using the linear force-free spheromak model incorporated into the EUHFORIA model. We place a swarm of ~20000 spacecraft in the 3-D simulation domain, and characterize ICME magnetic complexity and coherence at each spacecraft based on simulated time series.
Our simulations indicate ICMEs retain a lower complexity and higher coherence along their magnetic axis, but that a characterization of their global complexity requires crossings along both the axial and perpendicular directions. For an ICME that does not interact with other large-scale solar wind structures, global complexity can be characterized by as little as ~7 spacecraft, but the minimum number of spacecraft rises to ~50-65 when interactions occur. Without interactions, the coherence scale of the magnetic field strength around a reference observer extends through the whole structure, while it may be significantly smaller for the magnetic field components. The coherence scale is lower (higher) in the ICME west (east) flank due to Parker spiral effects, and is reduced by up to a factor of 6 due to interactions with solar wind structures. Our findings help constrain some of the critical scales controlling the evolution of ICME magnetic structures, and provide indications on the appropriate spatial configuration for future dedicated multi-spacecraft missions. | | 6 | Comparing flux rope CME models in EUHFORIA | Maharana, A et al. | Poster | | | Anwesha Maharana[1],Luis Linan[1],Stefaan Poedts[1,2] | | | [1]Centre for mathematical Plasma Astrophysics, KU Leuven, Belgium; [2]Institute of Physics, University of Maria Curie-Skłodowska, Lublin, Poland | | | Coronal mass ejections are giant expulsions of magnetized plasma from the Sun that manifest a flux rope structure in the interplanetary medium. These flux ropes are modeled with different types of geometry and internal magnetic field structures, and thus they possess different capabilities for operational space weather forecasting. Flux rope CME models such as the spheromak model with spherical geometry and the FRi3D model with a global CME geometry are already functional in studying CME evolution and propagation in the heliosphere with EUropean Heliosphere FORecasting Information Asset (EUHFORIA). Although the realistic flux rope geometry of FRi3D is an upgrade over the spheromak model, its complex geometrical transformations stand as a drawback in its implementation in EUHFORIA for faster simulations.
In this study, we try to find an optimal setup where the geometry is better than the spherical plasma blob and the simulations are still fast enough for operational forecasting setup. Therefore, we tried a torus geometry for our novel flux rope CME model. In this toroidal CME, we adopt the analytical constant alpha force-free magnetic field configuration of Miller and Turner (1981). The practical implementation advantage of Miller-Turner CME over FRi3D is that it is an analytical model which means it can be implemented via time-dependent boundary conditions. Moreover, it can be pushed completely through the inner boundary and it thus is not interfering with the following CMEs. We apply the Miller-Turner flux-rope model to an observed CME event and compare the related geo-effectiveness predictions with the geo-effectiveness obtained with spheromak and FRi3D CMEs. With this novel analytical CME model, we explore its potential for the improvement of the computation time of high-resolution EUHFORIA runs and the strength of magnetic field components at Earth.
This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870405 (EUHFORIA 2.0) | | 7 | Validation of the magnetized ICME model in Icarus | Baratashvili, T et al. | Poster | | | Tinatin Baratashvili[1], Benjamin Grison[2], Brigitte Schmieder [1][3][4], Stefaan Poedts[1][5] | | | [1]Centre for Mathematical Plasma Astrophysics, Dept. of Mathematics, KU Leuven, 3001 Leuven, Belgium, [2]Institute of Atmospheric Physics CAS, Dept of Space Physics, 14100 Prague, Czech Republic, [3]LESIA, Observatoire de Paris, 5 place Jules Janssen, 92190 Meudon, France, [4]SUPA, School of Physics & Astronomy, University of Glasgow, G12 8QQ, UK, [5]Institute of Physics, University of Maria Curie-Skłodowska, ul. Radziszewskiego 10, 20-031 Lublin, Poland | | | 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 AMR criteria 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 multiple spacecraft. We examine the capabilities of the model in different CME 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.
With different AMR criteria the complex structure of the magnetic field can be simulated with higher accuracy. Higher resolution is especially important for the spheromak model, because the internal magnetic field configuration affects the CME evolution and its interaction with the heliospheric wind significantly. 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). | | 8 | Solar Energetic Particle Environment Modelling (SEPEM) Reference Data Set (RDS) - Version 3 | Jiggens, P et al. | Poster | | | Piers Jiggens[1], Osku Raukunen[2], Ingmar Sandberg[3], Shannon Mutch[1], Rami Vainio[4], Daniel Heynderickx [5], Juan Rodriguez[6], Angels Aran[7], Marco Vuolo[1], Sigiava Aminalragia-Giamini[3] | | | 1] ESA/ESTEC, [2] Aboa Space Research Oy, [3] Space Applications & Research Consultancy, [4] University of Turku, [5] DH Consultancy, [6] NOAA/NCEI, [7] University of Barcelona | | | For the past decade ESA’s Solar Energetic Particle Environment Modelling (SEPEM) system has maintained a Reference Data Set (RDS) - a contiguous dataset of SEP measurements from the 1970s to the present day. This is intended to take benefit of monitor data which rarely saturates and science data with their finer energy resolution. The dataset is based on data from the GOES series of satellites (and the precursor SMS satellites) cross-calibrated, where appropriate, with data from IMP-8/GME. The dataset now has an extended energy range from 5 MeV up to 1 GeV protons courtesy of data from the HEPAD instruments and from 5 to 95 MeV/nucleon for helium.
Version 3 of the RDS will come with 4 versions enabling users to reproduce results and allowing them to apply their own algorithms in place of those from the SEPEM team. V3.0 includes the correction of data caveats (spikes and gaps) and is published with the calculated effective and bow-tie energies, this includes the high-energy HEPAD data. Version 3.1 includes new signal extraction and background subtraction routines which are critical for analysis of particles of only solar origin, Version 3.2 provides homogenous interpolated spectra and Version 3.3 is a space weather version of the dataset in which contamination from higher energy particles during solar particle event onsets are corrected.
The SEPEM RDS v3 will be of use to scientists and engineers working in specification modelling and space weather forecasting applications. The presentation will include a review of the detectors exploited and the methodologies applied at each step of the process plus how to access the data.
| | 9 | Wave observations in the solar wind during the September 2017 solar flares and coronal mass ejection events | Loto'aniui, P et al. | Poster | | | Paul T.M. Loto'aniu[1,2] | | | [1]CIRES-University of Colorado, [2]NCEI-NOAA | | | The NOAA DSCOVR spacecraft went operational in July 2016 at the 1st Lagrange point (L1) and provides continuity for NOAAs space weather solar wind observations. The magnetometer onboard DSCOVR samples the interplanetary magnetic field at 50 samples/second presenting unique opportunities to study plasma waves and turbulence in the solar wind up to the instruments 25 Hz Nyquist. In this study, we present Alfven wave observations during the September 2017 solar flares and coronal mass ejection events. The waves were observed mainly between the 4-6th and 10-12th September, with wave frequency mostly below 10 Hz. We will present the wave properties including frequency range, wave power and polarization. In addition, we discuss possible generation mechanisms and any connections between the waves and particle acceleration including the solar energetic proton enhancements that occurred during these periods. We also present validation of the DSCOVR solar wind parameters against Wind and ACE observations and discuss the importance of multi-spacecraft solar wind observations. Finally, we explain how users can access this distinctive full high-resolution magnetic field dataset through the NOAA-NCEI DSCOVR portal. | | 10 | Effect of Alfven Wave Turbulence on the Decay Phase of SEP Events | Tenishev, V et al. | Poster | | | Valeriy Tenishev, Lulu Zhao, Igor Sokolov | | | University of Michigan | | | Understanding the radiation environment due to solar energetic particles in the heliosphere and the Earth’s magnetosphere is a challenging and practically important task. The most vulnerable are exploratory missions when outside of the Earth’s magnetosphere.
In this work, we investigate the effect of pitch angle scattering on the decay phase of SEP events. We model the transport of solar energetic particles moving along magnetic field lines by solving the focused transport equation. The length of these magnetic field lines extends up to 5 AU to capture the effect of possible pitch angle scattering when energetic particles are beyond 1 AU. The latter could have a significant impact on the decay of a SEP event. Modeling the transport of SEPs is coupled with simulating the solar wind dynamics, interplanetary magnetic field, and parameters of the Alfven wave turbulence.
This presentation discusses the integrated modeling approach employed in this study and the effect of the pitch angle scattering at large heliocentric distances on the dynamics of the decay phase of SEP events.
| | 11 | Study of propagation of CME in the heliosphere using SWASTi framework | Mayank, P et al. | Poster | | | Prateek Mayank[1], Bhargav Vaidya[2] | | | [1]Indian Institute of Technology Indore | | | Coronal Mass Ejections (CMEs) are the central components of solar eruptions and are observed as magnetized plasma structures expanding in the solar wind (SW). SW streams, acting as a background, govern the propagation of CMEs in the heliosphere and drive geomagnetic storm activities. Therefore, the accuracy of SW parameters is very crucial for forecasting CME properties and its arrival time at Earth. Here, we present an indigenous MHD-based SW and CME model. The SW model is based on a two-domain approach; a semi-empirical coronal domain and an MHD-based inner-heliospheric domain. The CMEs are injected into the ambient solar wind model using the cone model, with their initial parameters obtained from the DONKI catalogue. In particular, the implementation and initial results of the new CME module of the Space Weather Adaptive SimutaTion (SWASTi) framework will be presented. The SWASTi framework is based on the PLUTO code and uses GONG/HMI magnetograms as input data. In addition to a detailed modelling methodology, the initial validation results will be shown by comparing the simulation results at L1 with OMNI data. Furthermore, we will demonstrate the effect of ambient SW and stream interaction regions (SIRs) on the propagation of CME in the heliosphere. Conclusively, we will show that SIR does play a significant role in affecting the azimuthal expansion of magnetic clouds corresponding to CMEs. | | 12 | A new reconstruction of solar energetic particle fluence for GLE events | Koldobskiy, S et al. | Poster | | | Sergey Koldobskiy[1], Osku Raukunen[2], Rami Vainio[2], Gennady Kovaltsov[1], Ilya Usoskin[1] | | | [1]University of Oulu; [2]University of Turku | | | A ground-level enhancement (GLE) is defined as a strong event with high-energy solar energetic particles (SEPs) detected by the network of ground-based neutron monitors. Until now, 73 GLEs have been registered. In this work, we report a new reconstruction of the event-integrated spectra (fluences) of SEPs
during 59 moderate and strong GLE events detected by NM network and satellite experiments. The reconstructions of SEP fluences are based on the “bow-tie” method employing the latest advances in NM
data analysis (time-dependent GCR background and the use of the altitude-dependent NM yield function directly verified with the AMS-02 experiment data) and a detailed study of different uncertainties. As a result of this work, we obtained fluences of SEPs in the energy range from 30 MeV to a few GeV for GLE
events since 1956, which were fitted with the modified Band-function (a double power-law function with two exponential cutoffs). An easy-to-use presentation of SEP fluences in the form of an analytical expression makes a solid basis for new studies in various fields, such as the influence of SEPs on the atmosphere and a statistical study of extreme solar activity. | | 13 | Galactic Cosmic Ray Variation Caused by Interacting Earth-Impacting Coronal Mass Ejection | Maričić, D et al. | Poster | | | Filip Šterc, Darije Maričić, Ivan Romštajn, Dragan Roša, Damir Hržina | | | Zagreb Astronomical Observatory, Opaticka 22, 10000 Zagreb, Croatia | | | We investigate the distribution of galactic cosmic ray (GCR) caused by interacting Earth-impacting interplanetary coronal mass ejections (ICMEs). Observations from different satellites are used to determine whether each CME under study is Earth directed or not. For Earth-directed CMEs, a kinematical study was performed to estimate the CME arrival time at 1 AU and to link the CMEs with the corresponding in situ solar wind counterparts. Based on the extrapolated CME kinematics, we identified isolated CMEs, which are excluded from further analysis. Applying this approach, a set of 26 interacting Earth-impacting CMEs was unambiguously identified and related to the in situ measurements recorded by the Wind spacecraft. Interacting Earth-impacting CMEs were analyzed in more detail considering the magnetic field strength, the plasma characteristics and variation of the GCR flux within an whole complex internal structure of the disturbance.Furthermore, analysis revealed well-defined correlations between variations of the GCR and the variation of the magnetic field strength, DB, bulk solar wind speed, Dv and proton thermal speed Dvth. All three correlations have high correlation coefficients cc = 0.64, 0.71 and 0.66, respectively. A mathematical model, capable of describing the distribution of the cosmic-ray density in interacting Earth-impacting CMEs is considered. | | 14 | Forecasting CMEs by addressing class imbalance using several machine learning models | Raju, H et al. | Poster | | | Hemapriya Raju, Saurabh Das,Srijani Mukherjee | | | [1]Indian Institute of Technology Indore; [2]University of Kalyani | | | Coronal Mass ejections and flares are part of the continuous physical process that happens in the solar atmosphere. Though flares and CMEs don’t drive each other, yet they have magnetic reconnection as an underlying physical process for eruptions. Forecasting such eruptions is necessary in this era of technology to avoid damages to satellites, blackouts to telecommunication systems. In this work, we evaluated the performance of 8 Machine Learning models (SVM,Linear Discriminant analysis, Random Forest, Decision Trees, Logistic Regression,Adaboost,Xgboost, Gradient Boost) in attempt of CME forecasting prior 4-48 hours of the actual event. SHARP features derived from HMI patches are utilized as input parameters for the prediction. The output is binary classification to forecast whether a flare will be accompanied by CMEs or not. Since the distribution of samples are biased towards the flare only class, we tried to address the class imbalance through different sampling techniques such as cost weight, Random Oversampling, Random undersampling, synthetic minority Sampling technique(SMOTE). We carefully separated the test set from sampling, and tested the model’s performance by sampling the training data set. We evaluated the confidence score through cross validation. We found that for 36 hour time lag, Random Oversampling(ROS) enhances the model performance of SVM and LDA. SVM with costweight fares True Skill Score(TSS) of 0.79±0.1, whereas with SVM with ROS sampling, tss score has improved to 0.83±0.04. LDA shows significant improvement in the Tss score of 0.8±0.05 at 36th hour after ROS sampling. LDA is able to achieve a lower False positive rate than SVM. Additionally, we observe that the SVM and LDA model’s TSS score increases significantly when change information, where the difference between 24 and 36 hour is included in the existing features. The change information of the features MEANSHR, SHRGT45, MEANGBH, MEANGAM, MEANALP plays a significant role in improving the prediction. | | 15 | Study of the propagation of the solar wind and coronal mass ejections: numerical MHD simulations and the comparison with observations | González, J et al. | Poster | | | J. J. González-Avilés [1], P. Riley [2], Michal Ben-Nun [3] | | | [1] Investigadores por México-CONACYT, SCIESMEX-LANCE, IGUM, UNAM, Morelia, Michoacán, México, [2] Predictive Science Inc., San Diego CA, USA. | | | In this work, we present a study of the dynamics of the propagation of solar wind (SW) currents and coronal mass ejections (CMEs) in the interplanetary medium using numerical MHD simulations in three spherical dimensions. Additionally, we show results for the SW's speed, density, and the magnetic field near the terrestrial environment (~1 AU). We also compare the results of the numerical simulations with the in situ measurements obtained by ACE, WIND, STEREO-A, Parker Solar Probe, and Solar Orbiter. Finally, we provide examples of forecasting the SW properties, the potential CME arrival at the Earth, and their implications in Space Weather. | | 16 | Sensitivity of model estimates of CME propagation and arrival time to inner boundary conditions when constrained by spacecraft data. | James, L et al. | Poster | | | Lauren James[1], Christopher Scott[1], Luke Barnard[1], Mathew Owens[1], Matt Lang[1]. | | | [1] University of Reading, Reading, United Kingdom | | | Forecasting the arrival of coronal mass ejections (CMEs) is important for enabling the mitigation of socio-economic risks associated with space weather. Through modelling of the event estimates of arrival time are provided. However, multi-view spacecraft observations are often not used to assess or improve model performance. The Heliospheric Imager (HI) camera onboard NASA's STEREO mission provides observations of enhanced plasma density during CME propagation through the heliosphere from two viewpoints outside the Sun-Earth line. Frequently, multiple enhanced plasma regions are identified in this data and here we present these ghost fronts as different features of the CME leading edge.
For the December 12th 2008 Earth-directed CME, we simulate the propagation with the simplified-physics HUXt model and explore how the time-elongation profiles of enhanced plasma density can be used to describe the location of the CME nose and flank. By computing an ensemble, we then investigate how model performance correlates to the arrival time error. Therefore, seeking to find out if using multiple fronts to confine models could improve the hindcast uncertainty.
By showing that distortion of an event from a simple geometric shape is true to nature, we then explore the impact of allowing a CME to distort from a lower inner boundary on model performance, and as a result, the arrival time accuracy.
| | 17 | High time resolution shock and CME observations with Solar Orbiter’s Heavy Ion Sensor | Alterman, B et al. | Poster | | | B. L. Alterman[1], Stefano Livi[1], Christopher Owen[2], Philippe Louarn[3], Roberto Bruno[4], A. Fedorov[5], George Ho[6], Susan Lepri[7], Jim Raines[7], Antoinette Galvin[8], Frederic Allegrini[1], Keiichi Ogasawara[1], Peter Wurz[9], Ryan Dewey[7], Yeimy Rivera[10], Sarah Spitzer[7], Christopher Bert[7], Kylie Sullivan[11], Tim Horbury[12], Domenico Trotta[12], Heli Hietala[13], Milan Maksimovic[14], Andrew Dimmock[15], Yuri Khotyaintsev[15], Virginia Angelini[12], Ed Fauchon-Jones[12], Helen O’Brien[12] | | | [1]Southwest Research Institute; [2]Mullard Space Science Laboratory; [3]IRAP/University of Toulouse-France/CNRS; [4]INAF - IAPS Rome; [5]CESR; [6]JHU/APL; [7]University of Michigan; [8]University of New Hampshire; [9]Univerity of Bern; [10]Center for Astrophysics | Harvard & Smithsonian; [11]University of Texas at San Antonio; [12]Imperial College London; [13]Blackett Laboratory, Imperial College London; [14]Paris Observatory; [15]Swedish Institute of Space Physics | | | Solar Orbiter launched in February 2020. It carries the Heavy Ion Sensor (HIS), a time-of-flight mass spectrometer. HIS resolves ion composition and charge states at resolution comparable to ACE/SWICS at better than 10-minute resolution, an order or magnitude faster. With these observations, we gain unprecedented insight into CMEs, shocks, suprathermal ions, and the background state of the solar wind.
This poster covers two different HIS topics. First, we discuss HIS operations and capabilities. Second, we provide a high-level overview of different CMEs and shocks that the HIS team is currently investigating as part of our data validation and delivery efforts. These results illustrate the type of insights HIS can yield, including the complex structure of CMEs and flux ropes along with solar wind heating and suprathermal acceleration at shocks. | | 18 | Simulations of SEP events with the novel ICARUS+PARADISE model | Husidic, E et al. | Poster | | | Edin Husidic[1,2], Nicolas Wijsen[3], Tinatin Baratashvili[1], Stefaan Poedts[1,4], Rami Vainio[2] | | | [1]Centre for mathematical Plasma-Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium, [2]Department of Physics and Astronomy, University of Turku, 20014 Turku, Finland, [3]NASA, Goddard Space Flight Center, Heliophysics Science Division, USA, [4]Institute of Physics, University of Maria Curie-Sklodowska, Pl. M. Curie-Sklodowska 5, 20-031 Lublin, Poland | | | Coronal mass ejections (CMEs) are large eruptions of solar mass and magnetic field into space, representing the most violent manifestation of solar activity. During their propagation, fast CMEs generate shock waves that can efficiently accelerate so-called solar energic particles (SEPs) to energies of deka-MeV and beyond. Since SEPs can pose a significant hazard to astronauts and spacecraft, there is great interest in numerical simulations that can realistically model and predict the acceleration and transport of SEPs. We simulate SEP events in the inner heliosphere with the novel coupled model ICARUS+PARADISE. Using the MPI-AMRVAC-based ICARUS code that implements adaptive mesh refinement, we generate realistic background solar wind configurations at heliocentric distances from 0.1 au onward and include superposed transients. To study the propagation of SEPs, we use the PARADISE (PArticle Radiation Asset Directed at Interplanetary Space Exploration) code. PARADISE takes solar wind configurations obtained from ICARUS as input to calculate energetic particle distributions by solving the focused transport equation in a stochastic manner. Recent results of these simulations are presented. | | 19 | Electron beam plasma instabilities and their multiple implications in the space weather context | Lazar, M et al. | Poster | | | Marian Lazar[1,2], Rodrigo A. Lopez[3], Shaaban M. Shaaban[4], Stefaan Poedts[1,5] | | | [1]Centre for mathematical Plasma Astrophysics, KU Leuven, Belgium; [2]Theoretical Physics IV, Ruhr University Bochum, Germany; [3]Departamento de Fisica, Univ. de Santiago de Chile, Usach, Chile; [4]Physics Department, Mansoura University, Egypt; [5]University of Maria Curie-Skłodowska, Lublin, Poland | | | Wave instabilities driven by electron (counter)beams are thought to be at the origin of radio emissions from interplanetary shocks, including those associated with CME events, planetary bow shocks, and even auroral sources in planetary magnetospheres. In this case, the most plausible scenarios invoke the instabilities of Langmuir electrostatic waves, which can be generated by high-energy electron (counter)beams, with energies > 100 keV. However, the electron (counter)beams are often observed at much lower energies, around 1 keV or even less, and with a large thermal spread. These plasma conditions have been less investigated, being favorable to other instabilities of different nature, but similar to electron heat-flux instabilities studied in the context of high-speed (fast) solar winds. We show that these instabilities can be involved in the generation of radio emissions, but can also be responsible for the erosion and isotropization of electron beams. Decoding the regimes of these instabilities helps to understand the origin of different radio emissions, but also the mechanisms that contribute to the transfer/dissipation of energy from large to small scales. | | 20 | Monte Carlo Markov Chain inference of the Probabilistic Drag Based Model’s parameters for Coronal Mass Ejection propagation | Francisco, G et al. | Poster | | | Simone Chierichini [1,2], Teresa Barata[3], Enrico Camporeale [4,5], Joao Fernandes [6], Raffaello Foldes [7,8], Gregoire Francisco [2,9], Giancarlo de Gasperis [2,10], Luca Giovannelli [2], Dario Del Moro [2], Ronish Mugatwala [1,2], Gianluca Napoletano [2], Jannis Teunissen [11] | | | [1] School of Mathematics and Statistics, University of Sheffield, [2] Department of Physics, University of Rome Tor Vergata, [3] University of Coimbra, Instituto de Astrofísica e Ciências do Espaço, [4] CIRES, University of Colorado, Boulder, CO, USA, [5] NOAA Space Weather Prediction Center, Boulder, CO, USA, [6] University of Coimbra, Centre for Earth and Space Research, [7] Dipartimento di Scienze Fisiche e Chimiche, Universita degli studi dell’Aquila, [8] Laboratoire de Mecanique des Fluides et d’Acoustique, CNRS, Ecole Centrale de Lyon, Universite Claude Bernard Lyon 1, [9] University of Coimbra, [10] INFN sezione di Roma2, [11] Centrum Wiskunde & Informatica, Amsterdam, The Netherlands | | | With an increasing dependence of the world on technological infrastructure, our societies became more vulnerable to space weather phenomena. Coronal Mass Ejections (CMEs) are violent eruptions of plasma and magnetic fields from the corona and are one of the space weather events most likely to cause disturbances in the Earth's technosphere. To mitigate the risk these events represent, we model the way CMEs propagate in the heliosphere in order to accurately forecast their arrival on earth. The drag-based model (DBM) is one such model. DBM describes the propagation of the CMEs in the interplanetary solar wind as analogous to an aerodynamic drag. The DBM is based on the so-called drag-based approximation which consists in considering that forces other than the solar wind drag are negligible. This approximation results in a simple analytical model characterized by the drag parameter $\gamma$ and the solar wind speed $w$ from which the CME transit time can be estimated with a low computational cost. The probabilistic drag-based model (P-DBM) has been recently proposed as an extension of the DBM to quantify the uncertainty associated with the predictions resulting from the model. We further investigate the P-DBM by inferring the a-posteriori probability distribution functions (PDFs) of the $\gamma$ and $w$ parameters of the DBM, using Monte Carlo Markov Chains (MCMC) as a Bayesian inference method. Our results show that a common posterior $\gamma$ PDFs can be inferred for CMEs travelling either in fast or slow solar wind speed. This common $\gamma$ distribution and the inferred solar wind speed posteriors PDFs for CMEs travelling in either fast or Sdw Solar Wind allows for robust operational application of the P-DBM to forecast CME arrival times and velocities in real-time.
| | 21 | Energetic Storm Particle events: proton energy spectra and relation with magnetic turbulence nearby IP shocks | Chiappetta, F et al. | Poster | | | Federica Chiappetta[1], Monica Laurenza[2], Fabio Lepreti[1], Giuseppe Consolini[2], Simone Benella[2] | | | [1]University of Calabria, Rende, Italy; [2]INAF-IAPS, Roma, Italy | | | Most of the energetic particles observed in the heliosphere are accelerated by shock waves propagating in the interplanetary space. In order to have information on the acceleration processes of particles at the shocks associated with energetic storm particle events (ESP), we analyzed kinetic energy spectra of proton flux enhancements. We considered ESP events occurring either in association with or in absence of solar energetic particles (SEPs), by using data from particle instruments aboard STEREO A spacecraft in the energy range from 84.1 keV to 100 MeV. For the ESP events associated with SEPs for quasi-perpendicular shocks, the Weibull distribution provides good fits to the spectra, over the whole energy range for some events, and only at high energies for the others, being lower energies explained by the power law predicted by the DSA. Instead, the SEP spectra at quasi-parallel shocks are better described by a double power law. For ESP events not associated with SEPs, the Ellison-Ramaty form fits the observed spectra, as expected from the DSA. We found also a significant correlation of the downstream magnetic field intensity fluctuations with the proton flux enhancements in the intermediate energy range 4-6 MeV for all the ESP events associated with SEPs, and with the Weibull parameters for quasi-perpendicular shocks. Our results suggest that the downstream turbulence is a relevant factor in particle acceleration and that stochastic acceleration can be a plausible mechanism for re-acceleration at interplanetary shocks.
“This research has been carried out in the framework of the CAESAR project, supported by the Italian Space Agency and the National Institute of Astrophysics through the ASI-INAF n. 2020-35-HH.0 agreement for the development of the ASPIS prototype of scientific data centre for Space Weather.” | | 22 | A study of a M4.0 flare followed by a CME and a type II radio emission recorded at Solar Observatory Bucharest | Dumitru, L et al. | Poster | | | Octavian Blagoi, Liliana Dumitru, Cristian Danescu | | | Astronomical Institute of the Romanian Academy | | | We studied the M4.0 - class solar flare produced on March 28, 2022 (11:28 UTC), by active region (AR) 12975. A radio burst type II and an Earth direction Coronal Mass Ejection (CME) followed. The type II radio burst was detected by the CALLISTO radio spectrometer installed at Solar Observatory from Astronomical Institute of the Romanian Academy, a custom device for this kind of radio observations. Using a nonlinear force-free field (NLFFF) method we calculated the unsigned magnetic flux and extrapolated the configuration of the 3D coronal magnetic field using the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO), more specifically, photospheric magnetic parameters extracted from the Space-weather HMI Active Region Patch (SHARP) vector magnetogram. | | 23 | Galactic cosmic rays as signatures of coronal mass ejections | Kramarić, L et al. | Poster | | | Luka Kramaric[1], Mateja Dumbovic[1], Bojan Vrsnak[1], Bernd Heber[2], Ilona Benko[1], Malte Horlock[2], Karmen Martinic[1] | | | [1] Hvar Observatory, Faculty of Geodesy, University of Zagreb; [2] Department of Extraterrestrial Physics, Christian-Albrechts University in Kiel | | | Coronal mass ejections (CMEs) are eruptions of plasma and magnetic field from Sun's Corona. CMEs are observed with coronagraphs moments after erupting. CME's counterpart Interplanetary coronal mass ejection (ICME) shows several signatures in magnetic field and plasma data and is often followed by a sudden decrease in galactic cosmic ray (GCR) count (i.e. Forbush decrease). We looked for ICMEs followed by a distinct Forbush decrease and matched them with their CME counterparts. To confirm the ICME-CME association we used Drag-based model (DBM) that gives us the timeframe in which CME observed near Sun struck the Earth. By using ForbMod we made the best-fit function for ICME related Forbush decreases. After that we applied the best-fit function on our dataset and compared it to observed measurements from SOHO/EPHIN. As a result we got a corelation coefficient of 0.8 which is encouraging considering that our dataset consists of Forbush decreases of varying qualities including ones with unclear boundaries. Unclear boundaries present a problem because they have to be precisely determined in order to achieve the best results. | | 24 | Validation of the EUHFORIA model for cone and spheromak CME runs | Rodriguez, L et al. | Poster | | | Luciano Rodriguez [1],Daria Shukhobodskaia [1],Antonio Niemela [2,1],Anwesha Maharana [2,1],Christine Verbeke [1],Evangelia Samara[1,2],Jasmina Magdalenic [1,2],Robbe Vansintjan [1],Marilena Mierla [1,3],Ranadeep Sarkar [4],Emilia Kilpua [4],Eleanna Asvestari [4],Stefaan Poedts [2,5] | | | [1]Royal Observatory of Belgium, [2]KU Leuven, [3]Institute of Geodynamics of the Romanian Academy, [4]University of Helsinki, [5]University of Maria Curie Skłodowska | | | EUHFORIA is a 3D MHD solar and heliospheric model that simulates the solar wind and the evolution of Coronal Mass Ejections (CMEs). This work deals with the validation of this model using a dataset of 17 CMEs that arrived at the Earth (ICMEs). We show how the results of the validation for arrival times and geomagnetic impact, using the cone and spheromak CME models within EUHFORIA. We compare the output of the model with solar wind data measured at the L1 point. EUHFORIA provides good estimates in terms of arrival times and number of correctly predicted ICME arrivals and misses. This work is being carried out in the framework of the H2020 project EUHFORIA 2.0 (grant agreement No 870405), that aims at making significant improvements in CME flux rope modelling and integrate the state-of-the-art SEP emission and transport models in EUHFORIA and to couple this novel tool to ground and radiation effects models. | | 25 | Assessment of the near-sun axial magnetic field of a Coronal Mass Ejection observed by the Solar orbiter on 11 March 2022 | Koya, S et al. | Poster | | | Shifana Koya[1,2,3], Spiros Patsourakos[2], Manolis K Georgoulis[1], Alexander Nindos[2] | | | [1]Academy of Athens, Athens, Greece; [2]University of Ioannina, Ioannina, Greece; [3]University of Maria Curie-Skłodowska (UMCS), Lublin, Poland | | | On 10 March 2022, ESA/NASA mission SOHO observed an earth-directed CME (Coronal Mass Ejection) around 19:00 UT. Late on 11 March 2022, the CME arrived at the Solar Orbiter (SolO ) and was detected by the SolO’s magnetometer (MAG). SolO’s Solar Wind Analyser (SWA) instrument also recorded the event as a change in the properties of the solar wind. On 13 March, this CME finally passed over the L1 point and it was detected by NASA’s Wind spacecraft. An hour later, the CME interacted with the terrestrial magnetosphere, triggering polar aurorae. Tracing the CME back to the Sun, we found that it originated from NOAA solar active region (AR) 12962. We present here preliminary work based on a recently developed, method, that relies on the principle conservation of magnetic helicity, which supplies estimates of the near-Sun axial magnetic field of CMEs using photospheric vector magnetograms of the source region and applied it to the observed CME. The geometrical parameters of the CME, as required by our method are obtained by fitting the GCS magnetic flux rope model in STEREO/SECCHI and SOHO/LASCO observations. This study is useful for constraining a maximum likelihood estimation of the near-sun magnetic field of potentially geo-effective CMEs and can be incorporated into the initial conditions of inner-heliospheric MHD CME propagation models.
| | 26 | Numerical diffusion-expansion Forbush decrease model, ForbMod | Kirin, A et al. | Poster | | | Anamarija Kirin[1], Mateja Dumbović[2], Bojan Vršnak[2], Slaven Lulić[1] | | | [1]Karlovac University of Applied Sciences, Croatia, [2]Hvar Observatory, Faculty of Geodesy, University of Zagreb, Croatia | | | An analytical diffusion-expansion Forbush decrease (FD) model, ForbMod, first presented in Dumbović et al. (2018) provides a method to calculate FD amplitude from the parameters of the flux rope (FR) part of the ICME. In this model, FR has a cylindrical shape and it is initially free of cosmic ray (CR) particles. FR moves with a constant velocity and expands in an interplanetary space while the magnetic field inside it decreases. It's radius is a function of time and it expands self-similarly slowly filling with CR particles by perpendicular diffusion. We first modified the original ForbMod to include particles of all energies. Then we used it to obtain the values of power-law indices for the radius and magnetic field changes from the observed FD amplitudes in the center of the FR. Since power-law indices need to be calculated numerically, we test the numerical method and examine the range of values of FR parameters which would result in power-law indices being in the expected range. We apply the model to several events and analyse the results. | | 27 | A study of focused transport of particles using Monte Carlo simulation | Annie john, L et al. | Poster | | | Lidiya Annie John, Rami Vainio | | | University of Turku, Finland | | | Solar energetic particles (SEPs) are considered serious solar radiation threats to space technologies and humans in orbit. The sources of SEPs are solar eruptions on the Sun caused by solar flares and coronal mass ejections (CMEs). SEP events are classified as impulsive and gradual events. Gradual events are considered more threatening events due to their large size and long duration. In gradual events, solar particles are accelerated by diffusive shock acceleration processes in CME-driven coronal shocks. We used Monte Carlo simulations to model solar particle acceleration in coronal shocks. Many properties of relativistic particles can be observed through the study of focused transport of particles, including particle focusing in a divergent magnetic field and particle scattering by pitch angle diffusion. The velocity and spatial distribution of particles obtained at different simulation times are studied. We present the results obtained by modelling the focused transport of particles with various parameters and comparing them with theoretical results. | | 28 | Revised database of Coronal Mass Ejection characteristics from in-situ and remote observations | Mugatwala, R et al. | Poster | | | Ronish Mugatwala[1][2], Gregoire Francisco[1][3], Simone Chierichini[2][1], Gianluca Napoletano[4][1], Raffaello Foldes[4][6], Dario Del Moro[1], Robertus Erdelyi[2], Luca Giovannelli[1], Giancarlo de Gasperis[1], Enrico Camporeale[5] | | | [1]University of Rome 'Tor Vergata' , [2]University of Sheffield, [3]University of Coimbra, [4] University of L'aquila, [5]NOAA Space weather prediction center, Boulder,USA, [6]Laboratoire de Mecanique des Fluides et d'Acostique,CNRS, Universite Claude Bernard Lyon | | | One of the goals of Space Weather studies is to reach a better understanding of impulsive phenomena, such as Coronal Mass Ejections (CMEs), in order to improve our ability to forecast them and reduce the risk to our technological society. To do this, it is crucial to assess the application of theoretical models or even to create models that are entirely data-driven. The quality and availability of suitable data are of paramount importance. We have already merged public data about CMEs from both in-situ and remote instrumentation in order to build a database (DB) of CME properties. To evaluate the accuracy of such a DB and confirm the relationship between in-situ and remote observations, we have employed the drag-based model (DBM). DBM is an analytical model that assumes the aerodynamic drag caused by the surrounding solar wind to be the primary factor in the interplanetary propagation of CMEs. In fact, we explored the parameter space for the drag parameter and solar wind speed using a Monte Carlo approach to see how well the DBM described the propagation of each CME. With this method, we can validate or correct the initial hypotheses about solar wind speed, and also yield additional information about CMEs. Using a data-driven approach, this procedure allows us to present a homogeneous, reliable, and robust dataset for the investigation of CME propagation.
| | 29 | Radial Sizes and Expansion Behavior of ICMEs in Solar Cycles 23 and 24 | Doshi, U et al. | Poster | | | Urmi Doshi 1,2, Wageesh Mishra 3, Nandita Srivastava 4 | | | 1 Department of Physics, The M S University of Baroda, Vadodara, India 2 M P Birla Institute of Fundamental Research, Bengaluru, India 3 Indian Institute of Astrophysics, Bengaluru, India 4 Udaipur Solar Observatory, Physical Research Laboratory, Udaipur, India | | | We attempt to understand the influence of the heliospheric state on the expansion behavior of coronal mass ejections (CMEs) and their interplanetary counterparts (ICMEs) in solar cycles 23 and 24. Our study focuses on the distributions of the radial sizes and duration of ICMEs, their sheaths, and magnetic clouds (MCs). We find that the average radial size of ICMEs (MCs) at 1 AU in cycle 24 is decreased by ∼33% (∼24%) of its value in cycle 23. This is unexpected as the reduced total pressure in cycle 24 should have allowed the ICMEs in cycle 24 to expand considerably to larger sizes at 1 AU. To understand this, we study the evolution of radial expansion speeds of CME-MC pairs between the Sun and Earth based on their remote and in situ observations. We find that radial expansion speeds of MCs at 1 AU in solar cycles 23 and 24 are only 9% and 6%, respectively, of their radial propagation speeds. Also, the fraction of radial propagation speeds as expansion speeds of CMEs close to the Sun are not considerably different for solar cycles 23 and 24. We also find a constant (0.63 ± 0.1) dimensionless expansion parameter of MCs at 1 AU for both solar cycles 23 and 24. We suggest that the reduced heliospheric pressure in cycle 24 is compensated by the reduced magnetic content inside CMEs/MCs, which did not allow the CMEs/MCs to expand enough in the later phase of their propagation. Furthermore, the average radial sizes of sheaths are the same in both cycles, which is also unexpected, given the weaker CMEs/ICMEs in cycle 24. We discuss the possible causes and consequences of our findings relevant for future studies. | | 30 | Energy spectra of protons above 50 MeV obtained by the Electron Proton Helium INstrument (EPHIN) aboard SOHO. | Heber, B et al. | Poster | | | Bernd Heber[1], Malte Hörlöck[1], Stefan Jensen[1], Andreas Klassen[1], Patrick Kühl[1], Holger Sierks[2], Robert Wimmer[2] | | | [1]Christian-Albrechts-Universität Kiel; [2]Max-Planck-Institut für Sonnensystemforschung, Göttingen | | | A Ground Level Enhancement (GLE) measured by a neutron monitor is caused by ions especially protons with energies above 1 GV that need to be accelerated by the event. Energy spectra of protons covering from a few MeV up to several hundreds of MeV can only be measured from Space as for example by the Electron Proton Helium INstrument (EPHIN) onboard SOHO that is a particle telescope, consisting of a stack of 6 silicon semiconductor detectors surrounded by an anticoincidence detector. The instrument nominally measures protons and helium from 4 MeV/nucleon up to energies of 51 MeV/nucleon by the dE/dx-E-method. At higher energies these particles penetrate the telescope. As shown previously EPHIN provides sufficient information to obtain the flux of protons up to an energy of about a GeV. However, with the loss of a second detector it was thought that we lost the capability to obtain proton fluxes at these energies. Here we investigate a proxy that allow us to recover the information in a limited energy range up to about 700 MeV using the dE/dx-dE/dx-method allowing the investigation near relativistic proton events.
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