The Parker Solar Probe mission has been revolutionizing our understanding of the Sun for nearly half a solar cycle, providing unprecedented insights into its dynamic atmosphere. Having completed 22 of its planned 24 orbits during the mission's prime science phase, the spacecraft continues to deliver data of unmatched quality, captivating both the global scientific community and the public. Parker Solar Probe has already yielded paradigm-shifting discoveries, cementing its status as one of the most successful heliophysics missions to date. With the spacecraft and its instruments performing exceptionally well, the mission's future beyond the prime science phase looks exceedingly promising. I will provide an overview the mission's remarkable achievements and explore its potential as we move into the declining phase of solar cycle 25 and beyond.
How to cite: Raouafi, N. E.: Parker Solar Probe: From Exploration to Paradigm-Shifting Discoveries, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1180, https://doi.org/10.5194/egusphere-egu25-1180, 2025.
Last December the Parker Solar Probe attained the lowest perihelion distance of 9.8 solar radii for the mission. The Integrated Science Investigation of the Sun (ISʘIS), and the other instruments onboard, reported healthy status after the encounter and will transmit the collected data in February and March. ISʘIS measures energetic ions from ~20 keV to >100 MeV/nucand electrons from ~30 keV to 6 MeV and has provided unprecedented observations of solar energetic particle (SEP) events close to the Sun. Here we review the latest data and present some of the more striking results that have been obtained as solar cycle 25 approaches its maximum.
How to cite: Cohen, C.: Recent Results from the Integrated Science Investigation of the Sun on Parker Solar Probe, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14351, https://doi.org/10.5194/egusphere-egu25-14351, 2025.
We report observations of time-intensity profiles,pitch-angle distributions, spectral forms, and maximum energies of <500 keV/nucleon suprathermal (ST) H, He, O, and Fe ions in association with eleven separate crossings of the heliospheric current sheet (HCS) that occurred near perhelia during Parker Solar Probe (PSP) encounters E07-E21. We find that the ST ion observations fall into three categories, namely: 1) the E07 observations posed serious challenges for existing models of ST ion production in the inner heliosphere; 2) ST observations during 8 HCS crossings are consistent with a scenario in which the accelerated ions escape out of sunward-located reconnection exhausts; and 3) two HCS crossings (E14 & E20) when PSP traversed regions close to the reconnection exhaust and observed ST protons up to ~500 keV and >150 keV in energy. During the latter two crossings, PSP detected sunward-directed reconnection-generated plasma jets and sunward propagating energetic protons up to ~400 keV within the exhaust, thereby unambiguously establishing their origin from HCS-associated X-line located anti-sunward of PSP. We present detailed analysis of the evolution of the pitch-angle distributions and spectral properties during this crossing which have revealed, for the first time, important clues about the nature of ion acceleration via reconnection-driven mechanisms at the near-Sun HCS.
How to cite: Desai, M. and the Parker Solar Probe ISOIS, SWEAP, and FIELDS Science Teams: Ion Acceleration at the Near-Sun Heliospheric Current Sheet Crossings observed by Parker Solar Probe During Encounters 7-22, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2951, https://doi.org/10.5194/egusphere-egu25-2951, 2025.
Magnetic ejecta (ME) characterized by large-scale smoothly-rotating magnetic field lines inside interplanetary coronal mass ejections (ICMEs) may erode while interacting with the surrounding ambient solar wind plasma in the heliosphere. Erosion may occur while ICME-surrounding solar wind structures are in favorable conditions leading to magnetic reconnection with MEs. Erosion may peel off the outer layers of ME eventually leading to changes in their structures and magnetic properties. In this study, we analyze the erosion of three ICME events observed by very rare radial alignments of multiple spacecraft, where the spacecraft were within 3.5 degrees of angular separations. The three events were observed by pairs of spacecraft: (1) Parker Solar Probe (0.53 au) and Wind (0.997 au) on September 2023, (2) Solar Orbiter (0.85 au) and Wind (0.98 au) on November 2021, and (3) STEREO-A (0.95 au) and Wind (1.005 au) on August 2023. Analyzing the radial evolution of the magnetic, ion and supra-thermal electron properties and Alfvenicity inside the MEs, and reconnection exhausts at their boundaries, we assess the impact of erosion on the structures of ME and their geo-effectiveness. Thus, taking the opportunity of such rare spacecraft alignments, we comment on how erosion may impact ICME radial evolution and may lead space weather prediction operations to be more challenging in the heliosphere.
How to cite: Pal, S., Good, S., Jian, L., Nieves-Chinchilla, T., and Nicolaou, G.: Radial Evolution of Interplanetary Coronal Mass Ejections and Change of Their Geo-effectiveness Due to Erosion, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11303, https://doi.org/10.5194/egusphere-egu25-11303, 2025.
Observational analyses of the evolution and dynamics of coronal mass ejection (CME) case study events tend to employ a holistic approach that takes advantage of multi-point and multi-regime measurements. Ideally, well-observed CMEs can be followed from their eruption off the solar disc via multi-wavelength remote-sensing data, through their coronal and heliospheric evolution via white-light imagery, and up to their arrival at a spacecraft of interest via in-situ measurements at one or more locations. In practice, events that can be tracked consistently through multiple regimes and from multiple viewpoints are understandably rare, and most CME detections are characterised by some “missing pieces in the puzzle” and/or limited observational perspectives. In this presentation, we shall focus on an event that was imaged remarkably well in white light (by both coronagraphs and heliospheric imagers) but had its source region and eruption dynamics completely hidden from view.
On March 13, 2023 an exceptionally fast and energetic CME was released from the solar far side as seen from Earth. Alas, the two other spacecraft equipped with disc cameras—STEREO-A and Solar Orbiter—were also imaging mostly the Earth-facing Sun, leaving a critical observational gap into the source, topology, and onset of the eruption. On the other hand, the coronal and heliospheric evolution of the CME were well observed from these three viewpoints as well as by Parker Solar Probe, which was located closer in longitude to the eruption’s source region. We present a synthesis of available (off-limb) EUV and white-light remote-sensing observations that aims to infer the complex eruption and early evolution of the event as well as to contextualise in-situ measurements at Parker Solar Probe, which was impacted by the CME at a heliocentric distance of ~0.25 au. Finally, we highlight the importance of observing the far side of the Sun, which, among other advantages, can fill a crucial observational gap required for multi-viewpoint measurements of every CME.
How to cite: Palmerio, E., Hess, P., Bothmer, V., Jebaraj, I., Dresing, N., and Wijsen, N.: When Most of the Action is Hidden from View: A Synthesis of Observations of the Fast March 13, 2023 CME, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7400, https://doi.org/10.5194/egusphere-egu25-7400, 2025.
Energetic particles in the heliosphere are produced by flaring processes on the Sun or shocks driven by coronal mass ejections. These particles can be detected remotely through the electromagnetic radiation they generate (X-rays or radio emission) or in situ by spacecraft monitoring the Sun and the heliosphere. Here, we investigate the acceleration location, escape, and propagation directions of electron beams producing radio bursts observed with the Low Frequency Array (LOFAR), Parker Solar Probe (PSP) and Solar Orbiter (SolO) and compare it to hard X-ray (HXR) emission and in situ electrons observed at SolO. These observations are combined with a three-dimensional (3D) representation of the electron acceleration locations and results from a magneto-hydrodynamic (MHD) model of the solar corona in order to determine the connectivity to Solar Orbiter and relate the electrons observed remotely to in situ electrons. We observed a long-duration metric-decametric type II radio burst with good connectivity to Solar Orbiter, which also observed a significant in situ electron event. The injections times of the in situ electrons are simultaneous with the onset of the type II radio burst. The properties of the SolO electrons also indicate that shock acceleration is likely the main contributor to the observed fluxes, with a possible smaller contribution coming from the flare, given the presence of HXRs and type III radio bursts.
How to cite: Morosan, D., Dresing, N., Palmroos, C., Gieseler, J., Jebaraj, I., Pomoel, J., and Zucca, P.: Determining the possible acceleration regions of in situ electrons using space- and ground-based radio observations , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9971, https://doi.org/10.5194/egusphere-egu25-9971, 2025.
The Parker Solar Probe (PSP), launched in 2018, has already accumulated seven years of observations with the Wide-Field Imager for Solar Probe (WISPR), offering numerous opportunities to study different coronal structures in visible light, such as streamers, dynamic outflows of blobs, and expanding coronal mass ejections (CMEs). Their brightness profiles are of interest because they depend on the position of these coronal structures with respect to the Thomson Sphere (TS), defined as the sphere with a radius equal to the distance between the Sun and the observer (i.e., PSP). The same feature moving in the observer's line of sight will appear brighter when it is in the vicinity of the TS because it is closer to the Sun, hence its density and brightness are higher. A study by Nisticò et al. (2020) demonstrated how the brightness profiles of ray tracing simulated blobs in WISPR change depending on their position relative to the TS and their speed. We apply the same theoretical approach to simulated and actual observations of coronal streamers in WISPR. Their brightness variations help us to infer the dynamics, scattering angle, velocity, extension, and electron density of these structures. To validate our results, we use multiple approaches, including MHD modeling and triangulation techniques to determine the location and dynamics of coronal structures.
How to cite: Cappello, G., Temmer, M., Linton, M., Nisticò, G., Palmerio, E., Lienhart, A., Howard, R., Stenborg, G., Voulidas, A., Bothmer, V., and Liewer, P.: Investigating the Brightness of Coronal Rays with the Parker Solar Probe/WISPR Observations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13180, https://doi.org/10.5194/egusphere-egu25-13180, 2025.
Parker Solar Probe (Parker) is capable of making observations of type III radio bursts in their generation region. PSP recorded a type III radio burst with frequency decay down to the local Langmuir frequency and simultaneously slow electrostatic plasma waves near the Langmuir frequency, which often harmonics. From the electric field fluctuations, the k-value of the Langmuir wave is estimated to be 0.14 and kλd = 0.4 and the phase velocity of the Langmuir wave was <10000km/s. The oscillations on the main frequency and the first harmonics were also detected in magnetic field perturbations. We demonstrated the presence of the second rapid Langmuir wave seen in the observations as the addition of two waves, one of which has small frequency variations that arise because the wave travels through density irregularities. This wave-wave interaction guided by a dense electron beam in the presence plasma density irregularities leads to the generation of the electromagnetic waves observed as type III radio burst
How to cite: Agapitov, O., Mozer, F., Sauer, K., and Voshchepinets, A.: Generation of the Type III Radio Bursts: Comparison of the Model Results and Parker Solar Probe Observations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15565, https://doi.org/10.5194/egusphere-egu25-15565, 2025.
Type III solar radio emissions are intense wave phenomena originating from eruptive events in the solar corona. These emissions are produced by energetic electron beams traveling outward from the Sun along the magnetic Parker spiral. As these beams propagate, they generate intense electrostatic Langmuir waves, which are subsequently converted into freely propagating radio waves. These radio waves, characterized by their distinct dispersed signatures in the time-frequency domain, can be detected throughout the solar system.
However, their propagation is not straightforward. Local density variations in the solar wind plasma cause refraction and, in some cases, reflection of the waves. Such density variations between the source and the observer can obscure low frequency part of the emissions, limiting their propagation to frequencies above the local L-O cutoff frequency. Multi-point observations reveal that the spatial and temporal coincidence of type III emission sources and solar wind density structures modifies the lower-frequency boundary of the detected emissions.
Additionally, some emissions display stripe-like patterns, which are also attributed to local plasma density variations at their source. The fine structures of these low-frequency (<100 kHz) emissions can be resolved with the very high time-frequency resolution of the Radio and Plasma Wave (RPW) instrument onboard the Solar Orbiter. These observations provide valuable insights into the interaction between solar radio emissions and the solar wind plasma environment.
How to cite: Pisa, D., Souček, J., Santolík, O., Formánek, T., Taubenschuss, U., Maksimovic, M., Khotyaintsev, Y., and Boldu, J.: Fine structures of solar type III radio bursts observed in the inner heliosphere by Solar Orbiter, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8710, https://doi.org/10.5194/egusphere-egu25-8710, 2025.
The Parker Solar Probe and Solar Orbiter missions are uniquely equipped to study Type III solar radio bursts. Both spacecraft measure two components of the radio-frequency electric field with unprecedented time and frequency resolution. In addition, for the first time, both spacecraft are equipped with high-frequency magnetic sensors (up to 1 MHz), allowing direct measurements of the magnetic component of both Z-mode (slow extraordinary) and ordinary electromagnetic wave modes.
PSP repeatedly came closer to the source region than any other satellite before. This unique combination of capabilities provided exceptional data. The analysis of these wave data provided unambiguous evidence of the basic elements of the wave generation mechanisms: the initial generation of Langmuir or slow extraordinary waves, and the transformation of the primary waves into electromagnetic waves, producing fundamental and harmonic electromagnetic waves.
A major discovery is the determination of the polarization properties of these emissions: the fundamental emission is produced as a highly polarized ordinary wave, while the harmonic emission is produced as a much more diffuse, weakly polarized combination of ordinary and extraordinary waves. This discovery can be used to distinguish between fundamental and harmonic emissions.
These experimental studies were accompanied by theoretical and computer simulation studies, which allowed to determine the main physical mechanism of fundamental emission generation as a direct transformation of electrostatic waves into electromagnetic waves, and to confirm the generation of harmonic emission as a result of coupling of primary and reflected quasi-electrostatic waves.
The authors are greatful to ISSI for the support of the team "Beam Plasma Interaction and Type III Solar Radiobursts", and financial support by
NASA Grants: 80NSSC20K0697 and 80NSSC21K1770, and CNES Grants: “Parker Solar Probe” and “Solar Orbiter”
How to cite: Krasnosselskikh, V., Jebaral, I. C., Pulupa, M., Dudok de Wit, T., Voshchepynets, A., Larosa, A., Bale, S. D., Krafft, C., Volokitin, A., Agapitov, O., Cooper, T., Kretzschmar, M., and Balikhin, M.: Type III Solar Radio Bursts: recent progress due to PSP and Solar Orbiter measurements, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18165, https://doi.org/10.5194/egusphere-egu25-18165, 2025.
In a weakly magnetized and randomly inhomogeneous solar wind plasma where upper-hybrid wave turbulence is generated, electromagnetic radiation at plasma frequency is modeled theoretically and numerically. Owing to three independent approaches which lead to the same results (Particle-In-Cell simulations, theoretical and numerical modeling, as well as analytical calculations performed in the framework of weak turbulence theory extended to randomly inhomogeneous plasmas), electromagnetic emissions in the O-, X- and Z-modes, as well as their corresponding radiation rates, are calculated as a function of the ratio of the cyclotron to the plasma frequency ωc/ωp and the average level of random density fluctuations ΔN. These emissions are due to electrostatic waves transformations and mode conversion on random density fluctuations. In this view, the condition for appearance or absence of some modes, are discussed for the case of type III solar radio bursts.
How to cite: Krafft, C., Volokitin, A., Polanco-Rodriguez, F. J., and Savoini, P.: Electromagnetic wave radiation in turbulent magnetized and inhomogeneous plasmas : theory and simulations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6681, https://doi.org/10.5194/egusphere-egu25-6681, 2025.
The Sun is a prominent source of radio emission due to its proximity and solar activity. The most violent solar eruptive events, solar flares and coronal mass ejections (CMEs), can accelerate electrons, producing radio emissions often observed as bursts classified into different types. In particular, type IV radio bursts, which are routinely observed by the Parker Solar Probe (PSP), are associated with CMEs and electrons trapped within strong coronal magnetic fields. The distinct spectral and temporal features exhibited by these bursts enable inferences about the dynamics of CMEs and properties of the energetic particles. While spacecraft such as PSP provide valuable in-situ data supporting analysis of remotely obtained radio spectra, physics-based numerical models play a crucial role in enhancing our understanding of the mechanisms driving radio emissions.
In this talk, we present a novel coupling of three numerical models to simulate gyrosynchrotron (GS) emission from energetic electrons deep in the solar corona. Using the data-driven magnetohydrodynamic (MHD) coronal model COCONUT, we solve the 3D ideal MHD equations to derive coronal background configurations from 1 to 21.5 solar radii, including a CME modelled as a Titov–Démoulin flux rope. Subsequently, we utilise the particle transport code PARADISE to propagate energetic electrons as test particles through the MHD snapshots by solving the focused transport equation stochastically, obtaining spatio-temporal electron intensities. Finally, we use the solar wind parameters from COCONUT and the electron energy and pitch angle distributions from PARADISE as input to the Ultimate Fast GS Code (Kuznetsov and Fleishman, 2021), which computes emission and absorption coefficients that can be integrated along a line of sight to obtain radio spectra directly comparable to spacecraft measurements. This coupled approach illustrates how varying electron injection spectra and CME properties affect the observed radio spectra, offering insights into the energetic particles and CMEs. Furthermore, we highlight the potential of our model in future studies incorporating observational data.
How to cite: Husidic, E., Wijsen, N., Jebaraj, I. C., Linan, L., Vainio, R., and Poedts, S.: Modelling Gyrosynchrotron Emission from Energetic Electrons in the Solar Corona, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18867, https://doi.org/10.5194/egusphere-egu25-18867, 2025.
The rapid rotation of sunspots is considered as one possible mechanism for triggering solar eruptions. The sunspot rotation may also contribute to the accumulation of magnetic helicity in solar active regions. Studying the sunspot rotation and the underlying mechanisms behind this motion is crucial for enhancing our understanding of solar eruptions. We aim to investigate the relationships between rotational sunspots and solar eruptions, including solar flares and coronal mass ejections (CMEs), in a larger sample. In this study, we have examined the full-disk HMI vector magnetograms with temporal resolution of one day from 2011 to 2019 and found 163 active regions that exhibit a near-bipolar configuration with single or pair of sunspots. To determine the sunspot rotation, we first employed the Differential Affine Velocity Estimator for vector magnetograms (DAVE4VM) to the HMI vector magnetogram to calculate the photospheric velocity field. We then applied the Automated Swirl Detection Algorithms (ASDA;Liu et al. 2019) to the velocity field to verify the presence of sunspot rotation. All 163 active regions were analyzed for five-days evolution to detect rotational sunspots. Some previous studies have doubted whether sunspot rotation represents an actual motion. Therefore, in this study, we only focus on the long-time rotation lasting for at least 10 hours. The results indicate that only 38 active regions are associated with rotational sunspots. We subsequently estimated the duration of rotation and the average rotational velocity for each sunspot. The rotational durations range from 16 hours to 100 hours and the average rotational velocities range from 1.00 to 4.73 deg per hour. Interestingly, not all rotational sunspots are associated with CMEs. About 16 active regions with rotational sunspots produced eruptive flares. The average rotation duration of sunspots with CMEs is approximately 10 hours longer than the sunspot without CMEs, while the average rotational velocities remain similar.
How to cite: Wang, W., Liu, R., Liu, J., and Wang, Y.: A statistical study of rotational sunspots in solar cycle 24: Comparing with solar flares and CMEs, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9297, https://doi.org/10.5194/egusphere-egu25-9297, 2025.
In standard 2D eruption models, the eruption of a magnetic flux rope is associated with magnetic reconnection occurring beneath it. However, in a 3D context, additional reconnection possibilities arise, particularly involving interactions between the flux rope and the overlying arcades. This process results in the drifting of the legs of the erupting flux rope.
We show examples of such magnetic reconnections between erupting filaments interacting with coronal arcades, called ar-rf (arcade + rope – rope + flare loop), using AIA/SDO and IRIS data.
To understand the physical processes behind observations, we perform data-inspired MHD numerical simulations, which reproduce such magnetic reconnection between flux rope and overlying magnetic fields. Our model clearly exhibits the slippage of flux-rope field lines and the remote heating and flare ribbons due to such external reconnection.
How to cite: Schmieder, B., Guo, J., Joshi, R., Dudik, J., and Poedts, S.: 3D Magnetic reconnection in solar eruptions: observations and MHD numerical simulations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1796, https://doi.org/10.5194/egusphere-egu25-1796, 2025.
Forecasting the arrival of Coronal Mass Ejections at Earth depends on accurate characterisation of their three-dimensional structure and kinematics. This is usually achieved via forward-modelling; applying an assumed model of the CME structure to white-light observations, which may be achieved using a small number of observing spacecraft. An alternative approach is inverse modelling, whereby white-light images are treated as two-dimensional projections of the Thomson-scattered light from the 3D plasma distribution. Inversion of images taken from multiple vantage points is purely mathematical and allows the three-dimensional CME density structure to be constrained. However, the method requires multiple observing spacecraft and, to-date, it has enjoyed limited success when applied to CMEs.
We establish the effectiveness of the tomographic inversion method using synthetic imagery produced by state-of-the-art magnetohydrodynamic simulations using the CORonal HELiospheric (CORHEL) model. This is performed for a fleet of spacecraft, such that various combinations can be combined and used to perform tomography on the synthetic imagery, with the goal of establishing the minimum requirements for successful 3D CME reconstruction. We demonstrate how the number of observing spacecraft influences the solution, how well the technique is augmented using polarised brightness measurements and the optimal orbital configuration, including out-of-ecliptic observers.
How to cite: Barnes, D., Palmerio, E., Amerstorfer, T., Asvestari, E., Barnard, L., Bauer, M., Čalogović, J., Hess, P., Kay, C., Kenny, K., and Cappello, G.: Tomographic Inversion of Synthetic White-Light Images: Observing Coronal Mass Ejections in 3D, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18793, https://doi.org/10.5194/egusphere-egu25-18793, 2025.
The physical role played by small-scale activity that occurs before the sudden onset of solar energetic events (SEEs, i.e., solar flares and coronal mass ejections) remains in question, in particular as related to SEE initiation and early evolution. It is still unclear whether such precursor activity, often interpreted as plasma heating, particle acceleration, or early filament activation, is indicative of a pre-event phase or simply on-going background activity.
In this contribution we investigate the uniqueness and causal connection between precursors and SEEs using paired activity-quiet epochs. We focus on transient brightenings (TBs) and present analysis regimes to study their role as precursors, including imaging of the solar atmosphere, magnetic field, and topology analysis using archive data from the Atmospheric Imaging Assembly and the Helioseismic and Magnetic Imager on the Solar Dynamics Observatory. Applying these methods qualitatively to three cases, we find that prior to solar flares, TBs 1) tend to occur in one large cluster close to the future flare location and below the separatrix surface of a coronal null point, 2) are co-spatial with reconnection signatures in the lower solar atmosphere, such as bald patches and null point fan traces and 3) cluster in the vicinity of strong-gradient polarity inversion lines and regions of increased excess magnetic energy density. TBs are also observed during quiet epochs (i.e., no SEE activity) of the same active regions, but they appear in smaller clusters not following a clear spatial pattern, although sometimes associated with short, spatially-intermittent bald patches and fan traces, but predominantly away from strong gradient polarity inversion lines in areas with little excess energy density.
How to cite: Dissauer, K., Barnes, G., Leka, K., and Wagner, E.: Investigating the Uniqueness and Causal Relationship of Precursor Activity to Solar Energetic Events, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17740, https://doi.org/10.5194/egusphere-egu25-17740, 2025.
Previous statistical studies revealed that the tangential component of the solar wind velocity is positive (co-rotating) in the vicinity of the Sun but it turns its sign at about 0.2 AU. After it, this negative value increases toward 0.3 AU and gradually relaxes to zero at distances in excess of 10 AU. Since the intervals of a large negative tangential velocity component exhibit also enhanced cross-helicity, outward propagating Alfven waves generated in the outer corona were suggested as the most probable source of the observed deviation. However, the weak point of this conclusion is that the waves would deviate the solar wind velocity in all directions with the same probability. For explanation of this caveat, we use all available data gathered by PSP and analyze factors that can affect the velocity direction like waves, stream interactions or magnetic reconnection. As a result, we suggest interchange reconnection of closed lines of coronal loops with the open lines from nearby coronal hole as a most probable driver of the observed velocity reversal. However, this type of reconnection is expected at the source regions of the slow wind whereas the negative tangential velocity component was observed in the fast wind and we discuss a scenario that can explain this objection.
How to cite: Nemecek, Z., Durovcova, T., and Safrankova, J.: Evolution of solar wind velocity direction in the inner heliosphere, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4774, https://doi.org/10.5194/egusphere-egu25-4774, 2025.
In preparation for the PUNCH mission which is planned to be launched in 2025, we construct synthetic white light (WL) images of the inner heliosphere based on GAMERA 3D MHD output. GAMERA is a 3D MHD code whose capabilities have been extended to perform time-dependent solar wind simulations by frequently updating the input magnetograms and thus the boundary conditions at the inner boundary of the code, offering a much more realistic reconstruction of the solar wind propagation and evolution. By employing this capability, we explain the phenomena and structures of the solar wind we see in the synthetic WL images from multiple view points (ACE, STEREO, PUNCH) and compare with the traditional steady state MHD approach.
How to cite: Samara, E., Malanushenko, A., Provornikova, E., Arge, C. N., and Merkin, V.: The importance of time-dependent MHD solar wind simulations in the frame of the PUNCH mission , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13918, https://doi.org/10.5194/egusphere-egu25-13918, 2025.
The remote observations of braided solar coronal magnetic fields, together with in situ interplanetary measurements of (a) intermittent fluxes of energetic solar particles due to a large scale flaring magnetic field as well as (b) sustained small-scale magnetic fields reversals in the solar wind opens a new venue for interpretation of a wide range of heliospheric phenomena. The standard description of magnetic fields as a set of simple, (distorted) field lines is generalized to strongly structured topological features. Combining mathematical considerations, remote images and in situ satellite observations, we construct new characteristics of those topological magnetic structures, applying Braid and Knot Theory to physical configurations, deducing their topological invariants and constraining their evolution and stability, delineating the relaxation path to magnetized equilibria. The 3-dimensional interconnection between the mathematical braids and knots are applied to the topologically non-trivial magnetized structures from solar corona to the interplanetary medium. The analysis results in conjectures regarding (i) braids’ stability under oscillations and successive appearance and decay of magnetic loops, (ii) reconfiguration of braided structures into magnetic knotted configurations, (iii) their large-scale expansion into the solar wind resulting in the intermittent observation of the solar flare ions and (iv) emission of small-scale compound magnetic knots by solar wind resulting in switchback structures. Future high-quality missions are expected to delineate in higher resolution the structure and evolution of all these topological forms together with the required constrains for their appearance.
How to cite: Roth, I.: Topological features of the heliospheric magnetic fields., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2064, https://doi.org/10.5194/egusphere-egu25-2064, 2025.
This research will explore solar wind parameters and present evidences of additional acceleration of particles in 3D reconnecting current sheet formed in the interplanetary magnetic field. The observational results will be compared with simulations of particle acceleration in 3D reconnecting current sheet using particle-in-cell approach. We also show the variations of electron pitch-angle distribution (PAD) during spacecraft crossing reconnecting current sheets (RCSs) with magnetic islands. The energy gains and the PADs of particles would change depending on the specific topology of magnetic fields. Besides, the observed PADs also depend on the crossing paths of the spacecraft. When the guiding field is weak, the bi-directional electron beams (strahls) are mainly present inside the islands and located closely above/below the X-nullpoints in the inflow regions. The magnetic field relaxation near X-nullpoint converts the PADs towards 90◦. As the guiding field becomes larger, the regions with bi-directional strahls are compressed towards small areas in the exhausts of RCSs. Mono-directional strahls are quasi-parallel to the magnetic field lines near the X-nullpoint due to the dominant Fermi-type magnetic curvature drift acceleration. Our results link the electron PADs to local magnetic structures and directions of spacecraft crossings derived from in-situ observations by WIND, ACE and Parker Probe.
How to cite: Zharkova, V., Khabarova, O., and Malandraki, O.: Additional acceleration of solar wind particles in the heliosphere and diagnostics from space observations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20306, https://doi.org/10.5194/egusphere-egu25-20306, 2025.
JUICE was launched in April 2023, and it is now in its cruise phase to Jupiter, where it is scheduled to arrive in July 2031. JUICE carries a radiation monitor, namely the RADiation hard Electron Monitor (RADEM) to measure protons, electrons, and ions, detecting particles coming from the anti-Sun direction. On 2024 May 13, a large solar energetic particle (SEP) event took place in association with an eruption close to the western limb of the Sun as seen from Earth. Providentially, at that time JUICE was very closely located to STEREO-A, namely the difference in location was 0.13 au in radial distance, 0.3° in latitude, and 1.6° in longitude.
We analysed the interplanetary context through which the particles propagated using the ENLIL model combined with in-situ plasma measurements. We studied the proton anisotropies measured by near-Earth spacecraft and STEREO-A and focused on an isotropic period during the decay phase of the SEP event to compute the proton energy spectrum. We fit the STEREO-A spectrum and compared it to that measured by JUICE to estimate energy-dependent intercalibration factors.
The proton spectral indices measured by JUICE and STEREO-A were similar. The proton fluxes measured at the effective energy channels of 6.8 MeV, 22.2 MeV, and 31.6 MeV by the radiation monitor onboard JUICE agree within 15% with the STEREO-A measurements. The differences were slightly higher for the 14.0 MeV channel, which agrees within 30%.
How to cite: Rodríguez-García, L., Palmerio, E., Pinto, M., Dresing, N., Cohen, C., Gómez-Herrero, R., Gieseler, J., Santos, F., Espinosa Lara, F., Cernuda, I., Witasse, O., and Altobelli, N.: Comparing observations of the closely located JUICE and STEREO-A spacecraft during the widespread solar energetic particle event of 2024 May 13, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6498, https://doi.org/10.5194/egusphere-egu25-6498, 2025.
In this presentation we update the community on the current status of the Interstellar Mapping and Acceleration Probe (IMAP), the latest mission in the Solar Terrestrial Probes (STP) program of NASA’s Science Mission Directorate Heliophysics Division, which is slated to launch in September of 2025. With ten instruments, IMAP provides the complete set of observations to investigate two intimately coupled and vitally important research areas of Heliophysics: 1) the acceleration of energetic particles expelled from the Sun and 2) the interaction of the solar wind and energetic particles with the local interstellar medium. IMAP simultaneously examines particle injection and acceleration processes at 1 AU, while remotely imaging the global heliospheric interaction and its response to particle populations generated earlier through the aforementioned acceleration processes. That remote imaging is possible via the detection of Energetic Neutral Atoms (ENAs) that are being emitted when the charged particles expelled from the sun, and after they have been accelerated, interact with interstellar neutrals when they reach the heliospheric boundary. In addition to in-situ acceleration and remote ENA observations, IMAP instruments directly sample both interstellar neutral atoms and interstellar dust drifting into the heliosphere; interstellar pickup ions; solar wind ions, electrons, and magnetic field; and the Sun’s three-dimensional hydrogen “helioglow.” In addition to periodically downlinking the full science data, a subset of real time space weather data is continuously broadcast back to Earth from L1. For more information about IMAP and the great contributions from all of our 25 institutions, see https://imap.princeton.edu/. Please also Follow, Like, and Share us on Facebook.com/IMAPMission and Instagram@IMAPSpaceMission.
How to cite: Gkioulidou, M., McComas, D., Schwadron, N., and Christian, E.: IMAP Mission in the Runup to Launch , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12678, https://doi.org/10.5194/egusphere-egu25-12678, 2025.
The Sun is currently traversing the local interstellar medium at a relative velocity of approximately 26 km s−1. Due to the Sun’s motion, interstellar dust grains from the interstellar medium are transported trough the heliosphere’s boundary, from the upwind direction.
Dust grains in a space environment are subject to a variety of charging mechanisms, which result in an overall equilibrium charge on their surface. In the interstellar medium and in the solar wind, the primary charging mechanisms are plasma collection, secondary electron emission, and photoelectric emission. The charge acquired by a dust grain depends on a number of factors, including the size, composition, and structure of the dust grain itself, as well as on the characteristics of the surrounding environment.
The magnetic field that the dust grains encounter when approaching the heliosphere, starts to change into the heliospheric magnetic field. Hence, the motion of individual grains near the heliospheric interface changes due to the influence of the Lorentz forces. The amount of trajectory deflection depends on the charge-to-mass ratio of a grain. Consequently, not all interstellar dust grains enter the solar system.
We discuss the dust charging with a particular focus on the influence of the space environment conditions that are expected at different locations throughout the heliosphere, including its boundary regions and including short-term and long-term variations of space environment conditions due to solar activity. These are necessary to calculate the dust trajectories in particular at the heliospheric interface. The results will help to explain the physical processes occurring at the boundary of the heliosphere.
How to cite: Arnet, T. and Sterken, V. J.: Charging and Dynamics of Interstellar Dust at the Heliospheric Interface, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-923, https://doi.org/10.5194/egusphere-egu25-923, 2025.
The Plasma Wave Subsystem (PWS) onboard the Voyager spacecraft have continuously recorded dust impacts over the past ~50 years, from the inner solar system to the very local interstellar medium. Not originally intended for this measurement, PWS detects a large surge in voltage when a dust particle impacts the spacecraft body, is vaporized and ionized, and becomes an expanding cloud of charge which is measured by the electric field antenna. While Voyager 2 lost the ability to measure dust impacts after it experienced a waveform receiver failure around 60 AU, Voyager 1 has recorded impacts along its entire trajectory. Dust impacts are very characteristic within the waveform data and can be automatically selected, although a human-in-the-loop method needs to be used to verify each dust impact signal. The rate of dust impacts has varied throughout the Voyager 1 flight. At a radial distance of 30 AU, Voyager 1 measured dust at a rate of 3 +/- 1 impacts per hour. At 70 AU, that increased to a peak of 6 +/- 3 impacts per hour, then started to fall off again after passing the Termination Shock and again after crossing the Heliopause. The last group of measurements showed impact rates of about 3 +/- 2 per hour. Converting to flux units gives values in the range of what Ulysses obtained for interstellar dust, indicating the Voyager impacts are of the same origin. We present the full set of dust impact measurements as well as compare with New Horizons measurements over radial distance and model simulations that utilize different dust grain size distributions to bring more insight to the Voyager dust data set.
How to cite: Jaynes, A., Kurth, W., Gurnett, D., and Granroth, L.: 50 years of Interstellar Dust Measurements from Voyager 1, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20516, https://doi.org/10.5194/egusphere-egu25-20516, 2025.
Solar type III radio bursts are amongst the most intense emissions found within Solar System. The bursts are generated by the relativistic electron beams ejected from the Sun as they propagate through the corona and solar wind. One the key parameters that can control beam plasma interactions is level of the density fluctuations. The density fluctuations can change the local phase velocity of the Langmuir waves generated by the beam instability, resulting in changes of the resonant conditions of wave-particle interaction. Changes in the wave phase velocity during the wave propagation can be described in terms of probability distribution function determined by distribution of the density fluctuations. This enables an approach that describes beam-plasma interaction with a system of equations, similar to well known quasi-linear approximation, but with the conventional velocity diffusion coefficient and the wave growth rate are replaced by the averaged in the velocity space. This approach, known as probabilistic model, allows to describe generation of the Langmuir waves in randomly inhomogeneous solar wind in self-consistent manner. Although previous version of the probabilistic model could explain some of the observational features of the emission, it had significant limitation, as it did not include time of flight effects. Here we present results of the numerical simulation based on an updated set of equations that can describe generation of the Langmuir waves by the electron beam as it propagates from the source region up to 10 Solar radii.
How to cite: Voshchepynets, A., Krasnoselskikh, V., and Jebaraj, I.: Simulation of the beam plasma interaction in randomly inhomogeneous solar wind, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19891, https://doi.org/10.5194/egusphere-egu25-19891, 2025.
The self-consistent generation of type III radio emissions and their morphological features has been an open problem since the 1950s. Using data from the Parker Solar Probe, namely the radio frequency spectrometer (RFS) to analyze type III fine structures (striae) and link them to the statistical properties of density fluctuations from 13 to 60 solar radii obtained using the floating potential technique. We find that the average level of density fluctuations decreases with distance from the Sun, while the intermittency is high at the characteristic scales of the striae. Our findings demonstrate that the probabilistic model of beam-plasma interaction describes, step by step, the self-consistent generation of type III radio bursts, from the excitation of Langmuir waves to electromagnetic wave emission.
How to cite: Jebaraj, I. C., Voshchepynets, A., Krasnoselskikh, V., De Wit, T. D., Sioulas, N., Larosa, A., Colomban, L., Agapitov, O., Chen, C., Hlebena, M., Balikhin, M., and Bale, S.: Evolution of Randomly Inhomogeneous and Intermittent Plasma: Effects on Langmuir Wave Generation and Type III Radio Emission, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13125, https://doi.org/10.5194/egusphere-egu25-13125, 2025.
Type III solar radio emissions originate from a mode conversion of electrostatic Langmuir waves generated by an energetic electron beam. This electron beam creates a bump-on-tail instability in the electron velocity distribution function, generating Langmuir waves as the electrons propagate along the magnetic field lines in the solar wind. The Solar Orbiter spacecraft enables us to study Type III radio emissions and the Langmuir waves locally generated in the solar wind with a very high temporal resolution. Using electron velocity distribution measurements obtained by the Solar Wind Analyser (SWA) and Energetic Particle Detector (EPD) instruments, we model the plasma environment and numerically solve the dispersion relation. After deriving the dispersion relation for the generalized Langmuir/Z-mode, we successfully match the waveform data observed by the Radio and Plasma Waves (RPW) instrument with the theoretical prediction. Furthermore, we analyse the wave polarization properties, including a coherent high frequency magnetic component. Combining the solution of the dispersion relation and observations, we constrain the wave vector and provide valuable insights into the wave polarisation properties.
How to cite: Formanek, T., Santolik, O., Soucek, J., Pisa, D., Zaslavsky, A., Maksimovic, M., Kretzschmar, M., Owen, C., and Rodriguez-Pacheco, J.: Polarisation Analysis of in-situ observations of Langmuir/Z-Mode Waves by Solar Orbiter, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8896, https://doi.org/10.5194/egusphere-egu25-8896, 2025.
The existing fleet of spacecraft at 1 AU represents an important opportunity for multi-mission, multi-spacecraft direct investigations of heliospheric plasmas.
In this work, we focus on a strong interplanetary (IP) shock which crossed Wind, ACE, DSCOVR, THEMIS B and THEMIS C on 3 Nov 2021. Further, the shock was observed by well radially aligned Solar Orbiter at 0.8 AU. Such spacecraft configuration was used in a previous study to constrain the extent of the shock upstream populated by compressive structures (shocklets).
Here, we study the acceleration of protons up to 5 MeV energies and focus on the variability of energetic particle production. By cross-correlating energetic particle fluxes for the different vantage points, we find that the production of low energy (up to 100 keV) protons is strongly influenced by the local shock conditions, while high energy ones (up to 1 MeV) respond to the average shock conditions. At higher energies, we find that the energetic particle fluxes are modulated by large-scale structuring in the shock surroundings.
This study is relevant for IMAP, which will soon join such spacecraft fleet, and yield novel measurements of energetic particles at Lagrange point L1.
How to cite: Trotta, D., Horbury, T. S., and Giacalone, J.: Multi-spacecraft observations of particle acceleration in the near-Earth environment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5514, https://doi.org/10.5194/egusphere-egu25-5514, 2025.
Small-scale solar wind structures, consistently impacting Earth, provide a fundamental energy transfer from the Sun to the Geospace. However, what we measure at L1 might not be consistent with structures arriving at Earth. We explore how well OMNI data resemble direct near-Earth measurements using THEMIS. We focus on variations in large-scale solar wind structures such as coronal mass ejections (CMEs) and stream interaction regions (SIR) with their distinct substructures. Our study is based on existing CME/SIR lists of events defined by Koller et al. [2022] in OMNI data. For the given time ranges, we compare the timing and appearance of the structures in the solar wind plasma and magnetic field parameters as probed by OMNI and THEMIS. We find that, on average, correlations between the structures measured at OMNI and THEMIS increase with the length of the measured structure. In addition, we find shifts between the structure measurements of a few minutes. Moreover, for CMEs that could form a sheath, we found an above-average coverage in the THEMIS measurements. By providing a more comprehensive understanding of solar wind dynamics and the relationships between their substructures measured at different locations, this research will significantly contribute to the field of space weather and heliospheric physics.
How to cite: Blüthner, G., Stadlober-Temmer, M., Koller, F., and Volwerk, M.: Solar wind structures – correlation between OMNI and THEMIS data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5604, https://doi.org/10.5194/egusphere-egu25-5604, 2025.
Solar wind features a latitudinal structure that evolves during the solar activity cycle. The only in-situ measurements of the solar wind speed and density available so far were performed by Ulysses at the turn of the 20th and 21st centuries. They showed that when the solar activity is low, the wind is fast and rare, with an equatorial band filled with a slower but denser outflow. During epochs of high activity, the band of slow wind expands to all latitudes. However, details of possible north/south asymmetries and regular structure evolution at shorter time scales could not be established because the measurements were performed in-situ along a highly elliptical orbit with a period of the order of half of the solar cycle.
Complementary methods of monitoring the solar wind latitudinal profiles include remote-sensing observations such as interplanetary scintillations (IPS) and hydrogen Lyman-α backscatter glow observations. Existing analyses of IPS and helioglow observations returned somewhat conflicting conclusions. Helioglow maps observed by SOHO/SWAN suggested that the solar wind flux temporarily features flux maxima at mid-latitudes. Analysis of IPS observations for equivalent times did not reveal such maxima in the solar wind speed.
Insight from Ulysses resulted in a hypothesis that the energy flux of solar wind is latitudinally invariant, which cannot be verified without additional observations. A confirmation of this invariance would be an important milestone in the understanding of the solar wind emission mechanism and provide a handy tool supporting retrieval of the solar wind structure from observations of either IPS or the helioglow.
GLObal solar Wind Structure (GLOWS) is a Lyman-α photometer onboard Interstellar Mapping and Acceleration Probe (IMAP), dedicated to helioglow observations aimed at retrieval of the solar wind structure. We present how GLOWS observations can be interpreted to resolve the helioglow/IPS solar wind structure dilemma and to verify the hypothesis of latitudinal invariance of the solar wind energy flux.
How to cite: Kowalska-Leszczynska, I., Bzowski, M., Porowski, C., Strumik, M., and Kubiak, M.: How GLOWS will reveal the latitudinal structure of the solar wind, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3612, https://doi.org/10.5194/egusphere-egu25-3612, 2025.
Many proxies for assessing the eruptive activity of solar active regions (ARs) have been suggested, mostly based on measurements of the photospheric magnetic field. Here we test the usefulness of DC/RC (ratio of photospheric direct to return current) for assessing the ability of ARs to produce CMEs, and compare it with the amount of shear along the eruptive section of the polarity inversion line (PIL). We find that all source regions of eruptive flares have DC/RC > 1.63 and PIL shear > 45° (3.2 and 68° on average), tending to be larger for stronger events. Both quantities are on average smaller for source regions of confined flares (2.2 and 46°), albeit with substantial overlap. Many source regions, especially those of eruptive X-class flares, exhibit elongated direct currents (EDCs) bracketing the eruptive PIL segment, typically coinciding with areas of continuous PIL shear > 45°. However, a small subset of confined flares have DC/RC close to unity, very low PIL shear (< 38°), and no clear EDC signatures, rendering such regions less likely to produce a CME. A simple quantitative analysis reveals that DC/RC and PIL shear are almost equally good proxies for assessing CME-productivity, and comparable to other proxies suggested in the literature. We also demonstrate that an inadequate selection of the current-integration area typically yields a substantial underestimation of DC/RC.
How to cite: Torok, T., Liu, Y., Titov, V. S., Leake, J. E., Sun, X., and Jin, M.: Non-Neutralized Electric Currents and Eruptive Activity in Solar Active Regions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4170, https://doi.org/10.5194/egusphere-egu25-4170, 2025.
Direct observations in the inner heliosphere have been limited due to the large gravitational potential differences, leaving many aspects of the physical processes governing the propagation of interplanetary coronal mass ejections (ICMEs) and solar energetic particles (SEPs) unresolved. Recent multi-point observations by spacecraft such as BepiColombo (Benkhoff et al., 2021; Murakami et al., 2020), Parker Solar probe (Fox et al., 2016) and Solar Orbiter (Müller et al., 2020) offer unique opportunities to explore the radial and longitudinal evolution of solar ejecta in unprecedented detail (e.g. Hadid et al., 2021; Mangano et al., 2021).
In this study, we utilized the Solar Particle Monitor (SPM) aboard BepiColombo/Mio, a non-scientific housekeeping radiation monitor for scientific observations. SPM’s ability to measure higher energetic particles makes it particularly effective for studying phenomena such as SEPs and galactic cosmic rays. We developed a novel inversion method based on response functions derived from Geant4 (Allison et al., 2016) radiation simulations, and reconstructed the primary energy and flux of incident particles from SPM data (Kinoshita et al., 2025, JGR).
This method was applied to an SEP event observed in March 2022, when BepiColombo and STEREO-A were aligned along the same Parker spiral magnetic field line. The energy spectra from BepiColombo/SPM, BERM (Pinto et al., 2022) and STEREO-A/HET (Von Rosenvinge et al., 2008) showed remarkable similarity, suggesting a common origin. Additionally, SPM detected a Forbush Decrease (FD) event following the SEP, marking the arrival of an ICME. This ICME also reached Earth, where FD signatures were recorded by ground neutron monitors. A comparison of FD profiles such as shapes and depth between BepiColombo and the Earth provided insights into the spatio-temporal evolution of the ICME as it propagated in the inner heliosphere.
Our findings contribute to a deeper understanding of SEP acceleration mechanisms and ICME dynamics in the inner heliosphere. Moreover, they demonstrate the potential of repurposing housekeeping instruments for scientific applications, paving the way for expanding solar observation networks with ongoing and future missions.
How to cite: Kinoshita, G., Ueno, H., Murakami, G., Pinto, M., Yoshioka, K., Miyoshi, Y., and Saito, Y.: Unveiling SEP Acceleration and ICME Evolution in the Inner Heliosphere using Housekeeping Radiation Data Acquired by BepiColombo, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4776, https://doi.org/10.5194/egusphere-egu25-4776, 2025.
One of the commonly observed features of the solar wind is the simultaneous streaming of two different proton populations, one of which is the dominant denser core, and the other is the less dense and faster-propagating, minor population called the beam. The proton beam relative abundance is typically 10-20%, and the proton beam moves relative to the core along the interplanetary magnetic field at about 1.2 local Alfven speed. The origin and evolution of the proton beam is not yet fully understood. A previous study based on data from the Helios mission suggests that the seed of the proton beam forms close to the Sun, leading to the observed correlation between the relative abundance of the proton beam and alpha particles. The Parker Solar Probe (PSP) mission, which has already achieved its closest approach to the Sun, gives us an opportunity to study the proton beam parameters near the solar wind source regions. We focus on the non-thermal features of the ion velocity distribution functions (VDFs) observed near the Sun by PSP. We investigate the mechanisms that change the proton beam parameters both in the initial phase of the solar wind expansion and on its way towards the Earth.
How to cite: Satyasmita, S., Durovcova, T., Nemecek, Z., and Safrankova, J.: Study of the Proton Beam Parameters near the Sun, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6362, https://doi.org/10.5194/egusphere-egu25-6362, 2025.
Analyzing multi-instrument, multi-mission in-situ space physics data presents significant challenges, hindering scientific progress. The SCIentific Qt application for Learning from Observations of Plasmas (SciQLop) addresses these challenges by providing a comprehensive tool suite for simplified data discovery, retrieval, visualization, and analysis. SciQLop facilitates access to data from remote servers like CDAWeb and AMDA via tools like Speasy. Crucially, SciQLop integrates with event catalogs through TSCat and its associated GUI, allowing users to define and search for specific events and then seamlessly access the corresponding data across multiple instruments and missions. This poster demonstrates how SciQLop facilitates massive in-situ data analysis and event-based studies, empowering researchers to focus on scientific interpretation and accelerate discovery in space physics.
How to cite: Jeandet, A., Renard, B., Aunai, N., Ghisalberti, A., Génot, V., André, N., and Bouchemit, M.: SciQLop: A Tool Suite for Multi-Mission High-Resolution In-Situ Data Analysis in the Heliophysics Community, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10101, https://doi.org/10.5194/egusphere-egu25-10101, 2025.
Large-scale coronal waves, also called EIT waves (named after the Extreme Ultraviolet Imaging Telescope on the SOHO satellite they were first observed with), or extreme ultra violet (EUV) waves are fast magnetosonic magnetohydrodynamic waves caused by the fast lateral expansion of coronal mass ejections (CMEs). They may detach from their driver and are observed as bright fronts crossing large areas of the solar disk. As their initial speed can exceed the local magnetosonic speed, they can develop into large-amplitude waves or even shock fronts, which may be responsible for accelerating solar energetic particle (SEPs).
The EU Horizon project SOLER investigates energetic solar eruptions starting from three perspectives: fast CMEs, strong flares, and large SEP events to improve our understanding on how the eruptive phenomena are linked, how they interact with each other, and how they result in acceleration of high energy particles and their release from the solar corona into interplanetary space. In this study we present a tool for the analysis of large-scale coronal waves, and demonstrate its outcomes for several events during the May 2024 high activity period.
The Python tool automatically derives the speed and the amplitude evolution of the waves based on perturbation profiles. In order to analyze the imprints of large-scale coronal waves on the lower atmosphere layers, we need to extract the distance of the wave front from its origin for each time step. To do so, the solar full-disk image is split it equidistant circles on the spherical surface around the center of the wave. As estimate of the wave center, we use the position of the associated flare following previous studies. Since large-scale coronal waves usually reveal a non-isotropic propagation, these rings are split up further along the azimuthal direction into different sectors. The analysis is performed on base ratio images (where each image is divided by the same pre-event image), and for each segment the mean intensity value of the pixels is calculated. The segments along each considered propagation direction are combined into intensity profiles along great circles which originate at the flare position, so-called perturbation profiles. A peak finding algorithm marks the peaks and fronts of these perturbation profiles for the wave tracing algorithm. The wave tracing algorithm checks for continuously moving peaks, and applies linear fits to the obtained time-distance profiles to derive the wave speed.
We present the results for multiple waves that were associated with eruptive X- class flares that occurred between the 9th of May and the 15th of May 2024, observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory. The average wave propagation speeds obtained are in the range from 300 – 800 km/s, with the peaks of the perturbation amplitudes up to 1.4 in the AIA 211 Å filter.
This project has received funding from the European Union's Horizon Europe research and innovation program under grant agreement No 101134999. As part of the grant agreement the tool will be made public.
How to cite: Baumgartner-Steinleitner, M., Veronig, A., and Dissauer, K.: Demonstration of a new python tool for semiautomatic tracing of large-scale coronal waves on the events between May 9th and May 15th 2024, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17300, https://doi.org/10.5194/egusphere-egu25-17300, 2025.
Solar type III radio bursts are common radio emissions generated by energetic electron beams traveling through the solar corona. These serve as important remote sensing tools for studying plasma and electron beams in the solar wind. In this work, we aim to combine observations from both the Parker Solar Probe (PSP) and Solar Orbiter (SolO) spacecrafts in order to study solar type III radio bursts from different point of view and distances. In particular, we investigate observed differences in the fine structures, such as striae, as well as in the radio spectrum fluctuations to gain a deeper understanding of the physical mechanisms influencing the propagation of electrons beams.
How to cite: Thepthong, P., Kretzschmar, M., Maksimovic, M., and Pesini, A.: Joint Analysis of Solar Type III Radio bursts with Parker Solar Probe and Solar Orbiter, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10692, https://doi.org/10.5194/egusphere-egu25-10692, 2025.
The heliospheric current sheet (HCS) is observed as a sector boundary in the ecliptic plane, and its orientation and structure have been intensely studied. It divides the heliosphere into regions with opposite magnetic polarities. Analysis of its local structure at 1 AU let to study the HCS as a magnetic directional discontinuity supported by a current sheet (CS).
HYTARO+ is an analytical model development to evaluate the influence of the solar magnetic dipole in the topology of the local structure of the HCS. Using multipole expansion, HYTARO+ analyzes the contribution of the dipolar and quadrupolar magnetic field in the HCS. HYTARO+ deepens the study of the background magnetic field present in the analyzed current sheet crossings.
A preliminary analysis, evaluating the influence of the solar magnetic dipole in the topology of the local structure of the HCS, is summarized. The data provided by the Parker Solar Probe (PSP) and Solar Orbiter (SolO) instrumentation have allowed us to advance in the analysis of the multipole components of the IMF by performing location-dependent studies.
How to cite: Arrazola Pérez, D., Blanco Ávalos, J. J., Hidalgo Moreno, M. Á., and Jiménez, J. J.: Influence of the solar magnetic dipole in the topology of the local structure of the HCS, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16148, https://doi.org/10.5194/egusphere-egu25-16148, 2025.
The solar wind is permeated by Alfvénic fluctuations across a broad range of scales, with fluctuations that have an anti-sunward sense of propagation typically dominating. Recent studies have shown that cross helicity, which can be used to measure the difference between the sunward and anti-sunward fluctuation power, is more balanced inside interplanetary coronal mass ejections (ICMEs) than in the solar wind generally. A possible cause of balanced cross helicity in ICMEs is their closed magnetic field structure, with a closed loop connected at both ends to the Sun being able to support a more balanced population of Alfvénic fluctuations. To test this hypothesis, we have performed a statistical study that compares cross helicity with electron strahl signatures for a large number of ICMEs at 1 au. Bidirectional electrons are a well-established signature of closed magnetic field structures in ICMEs. A moderate correlation between bidirectional electrons and balanced cross helicity has been identified, supporting the closed-field hypothesis as an origin of the balanced cross helicity found in ICMEs.
How to cite: Good, S., Franc, A., Pal, S., and Kilpua, E.: Cross helicity and electron strahl signatures in interplanetary coronal mass ejections, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10642, https://doi.org/10.5194/egusphere-egu25-10642, 2025.
Coronal magnetic field models have to rely on extrapolation methods using photospheric magnetograms as boundary conditions. In recent years, due to the increased resolution of observations and the need to resolve non-force free lower regions of the solar atmosphere, there have been increased efforts to use magnetohydrostatic (MHS) field models instead of force-free extrapolation methods. Although numerical methods to calculate MHS solutions can deal with non-linear problems and hence provide more accurate models, analytical three-dimensional MHS equilibria can also be used as a numerically relatively “cheap” complementary method.
We discuss an extrapolation method based on a family of analytical MHS equilibria that allows for a transition from a non-force-free region to a force-free region. The solution involves hypergeometric functions and while routines for the calculation of these are available, this can affect both the speed and the accuracy of the calculations. We have looked into the asymptotic behaviour of this solution to approximate it by exponential functions which improves the numerical efficiency. We present results with boundary conditions based on artificial magnetograms to test the method, and also the application of the model to observational data.
How to cite: Nadol, L. and Neukirch, T.: Three-Dimensional Solar Magnetic Field Extrapolation Using Analytical Magnetohydrostatic Equilibrium Solutions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6910, https://doi.org/10.5194/egusphere-egu25-6910, 2025.
The Dynamic Eclipse Broadcast (DEB) Initiative is a network of volunteer citizen science telescope-observing teams that was initiated to observe the Annular Solar Eclipse of October 2023 and the Total Solar Eclipse of April 2024. 82 teams composed of amateur astronomers, university students, high school students, and astronomy enthusiasts were formed across North America. Teams participated in training events and practice sessions to be ready for the 2023 and 2024 solar eclipses. Weather permitting, each team collected a series of science and calibration images before, during, and after the eclipses with identical portable solar telescopes. The data collected by those teams during the 2024 Total Solar Eclipse is being processed to observe changes in the inner solar corona that occurred during the time that the Moon’s shadow moved across North America.
The project is now moving into a new phase, with teams using their equipment to observe and record white light high energy X-class solar flares. The high levels of activity on the Sun during solar maximum and the large geographic area covered by this telescope network have allowed the team to collect sub-second cadence data on four X-flares to date with preliminary analysis showing a white light flare signature in the highest energy X4.5 flare.
The DEB Initiative plans to continue its work, broadening its network across the planet by recruiting teams from around the world. Continued efforts are planned to observe solar flares as well as to collect another series of white light coronal images during the August 2, 2027, Total Solar Eclipse which will sweep across North Africa.
How to cite: Brevik, C., Baer, R., Penn, M., Mandrell, C., Henson, H., and Simões, P.: The Dynamic Eclipse Broadcast (DEB) Initiative: A network of volunteer citizen scientists observing the Sun, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14720, https://doi.org/10.5194/egusphere-egu25-14720, 2025.
Our heliosphere is surrounded by the Local Interstellar Medium. Their interactions lead to a range of observable phenomena such as energetic neutral atoms from the outer regions of the heliosphere and the influx of some interstellar neutrals into the inner solar system. Hydrogen is the dominant neutral species in the Local Interstellar Medium, but due to ionization and radiation pressure only a fraction of the interstellar neutral hydrogen atoms reach the inner solar system. Observing this signal therefore offers a reality check for our assumptions on the Local Interstellar Medium and on solar-activity dependent loss processes inside the heliosphere. So far, the IBEX-Lo instrument onboard the Interstellar Boundary Explorer in Earth orbit has been the only instrument to directly measure interstellar neutral hydrogen atoms.
This presentation shows the maps of 15 years of IBEX-Lo observations of the interstellar neutral hydrogen signal, covering more than one solar cycle and including two solar minima where the signal in IBEX-Lo is strongest. Despite the very intense interstellar neutral helium signal, the hydrogen signal can be retrieved with appropriate knowledge of the instrument, choice of optimum observation season, and supporting modeling. As expected, the retrieved interstellar neutral hydrogen signal is anti-correlated with solar activity. On the other hand, the discrepancy, known from earlier studies, between observed and predicted energy of the interstellar hydrogen atoms persists.
How to cite: Galli, A., Swaczyna, P., Bzowski, M., Kubiak, M. A., Kowalska-Leszczynska, I., Wurz, P., Rahmanifard, F., Schwadron, N. A., Möbius, E., Fuselier, S. A., Sokol, J. M., Gasser, J., Heerikhuisen, J., and McComas, D. J.: 15 years of interstellar neutral hydrogen observed with the Interstellar Boundary Explorer, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3201, https://doi.org/10.5194/egusphere-egu25-3201, 2025.
The Sun manifests its activity across different temporal scales and via transient phenomena that start from solar flares and, through energetic particles, coronal mass ejections, and solar wind, impact the whole heliosphere. The understanding of the causality of this chain of events is hampered by the fact that several open issues still bother a full comprehension of the trigger of such chain, i.e., solar flares. The present talk aims to shed some light on two specific aspects of these elusive phenomena characterizing the active Sun: the determination of the volume of a thermal flaring emission, and the estimate of its effectiveness as particle accelerator. For the first problem, we will show that computer vision applied to hard X-ray observations provided by STIX on-board Solar Orbiter and HXI on-board ASO-S is able to provide the three-dimensional reconstruction of the solar flare thermal emission. For the second problem, the application of an inversion method to STIX visibilities will contribute to settle the long-standing issue concerning the determination of the acceleration rate associated with magnetic reconnection.
How to cite: piana, M., volpara, A., massa, P., palumbo, B., ryan, D., su, Y., emslie, G., massone, A. M., benvenuto, F., and krucker, S.: The elusive solar flares: characterizing the trigger of the Sun-heliosphere connection, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19097, https://doi.org/10.5194/egusphere-egu25-19097, 2025.
Understanding the mechanisms that generate information flow in dynamical systems is crucial for advancing causal inference and dependency characterization in natural and engineered systems. Information flow is defined as the exchange of predictive or uncertainty-reducing knowledge between variables in a coupled system, arising when fluctuations in one component influence the variability in another. This study establishes that information flow emerges as a direct result of trajectory divergence in phase-space, an effect encoded in the generalized dynamics of probability density functions. We show that when the divergence of flow fields in phase-space is non-zero, it induces temporal changes in the entropic structure of the system. This expands the traditional Liouville equation to non-conservative systems. This divergence creates, rather than merely propagates, informational dependencies among system components, highlighting the dynamic nature of mutual and multivariate information in such systems.
Our results reveal that in conservative systems, where phase-space volume is preserved, the system entropy remains invariant, and informational dependencies are determined solely by initial conditions. In contrast, dissipative systems—exemplified by the damped harmonic oscillator and the Lorenz system—exhibit significant entropic and informational evolution driven by non-zero divergence. The mathematical framework presented quantifies the role of divergence in shaping joint, marginal, and conditional entropy, as well as bivariate and higher-order mutual information. This approach provides a comprehensive understanding of how phase-space dynamics underpin the flow and transformation of information.
The findings have profound implications across multiple domains, including environmental science, climate dynamics, and engineered systems, where causal relationships often arise from interactions between variables in complex networks. By bridging physical principles with information theory, the work offers a new lens for exploring the dynamics of natural and artificial systems, with potential applications in predictive modeling, data assimilation, and the design of resilient systems under uncertainty.
This investigation not only addresses a longstanding question about the origin of information flow in coupled systems but also lays the groundwork for future studies incorporating time-lagged dependencies and higher-order interactions in both theoretical and applied contexts. The framework proposed herein enables a more refined analysis of information flow in complex systems, advancing our ability to interpret, predict, and engineer their behavior.
How to cite: Kumar, P.: Phase-Space Divergence as the Driver of Information Flow in Dynamical Systems, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5249, https://doi.org/10.5194/egusphere-egu25-5249, 2025.
Nonlinear wave interactions as well as wave transformation processes on random plasma density inhomogeneities are thought to play a central role in electromagnetic wave radiation during type III solar radio bursts, in particular by generating radio waves at both the plasma frequency ωp and its harmonic 2ωp. Large-scale and long-term 2D Particle-In-Cell (PIC) simulations involving an electron beam generating upper-hybrid wave turbulence have been shown (e.g. Krafft et al. 2024 ApJL 967 L20) to be an efficient tool to study mechanisms as electrostatic decay, electromagnetic decay, wave coalescence, or conversion of modes at constant frequency. Here a local and a global approach are combined to evidence such mechanisms in weakly magnetized solar wind plasmas, and to study their properties as a function of plasma parameters as the cyclotron frequency ωc, the average level of random density fluctuations ΔN, and the ion-to-electron temperature ratio Ti/Te.
How to cite: Polanco-Rodriguez, F. J., Krafft, C., and Savoini, P.: Wave processes during type III solar radio burts : 2D PIC simulations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6736, https://doi.org/10.5194/egusphere-egu25-6736, 2025.
Posters virtual: Thu, 1 May, 14:00–15:45 | vPoster spot 3
EGU25-14886 | Posters virtual | VPS27
Circularly Polarized Type III Storms Observed with PSPThu, 01 May, 14:00–15:45 (CEST) | vP3.23
During the active phase of solar cycle 25, the Parker Solar Probe (PSP) spacecraft frequently observes circularly polarized Type III radio storms. The most intense and longest duration event occurred following a large coronal mass ejection (CME) on 5 September 2022. For several days following the CME, PSP observed a storm of Type III radio bursts. The polarization of the storm started as left hand circularly polarized (LHC) and switched to right hand circularly polarized (RHC) at the crossing of the heliospheric current sheet.
We analyze properties of this Type III storm. The drift rate of the Type IIIs indicates a constant beam speed of ~0.1c, typical for Type III-producing electron beams. The sense of polarization is consistent with fundamental emission generated primarily in the o-mode.
In addition to this prototypical event, we present a survey of radio observations throughout the PSP mission, demonstrating that the majority of encounters contain Type III storms, that the storms are typically strongly (but not completely) circularly polarized, and that the sense of polarization and the sign of the radial magnetic field are consistent with o-mode emission.
How to cite: Pulupa, M., Bale, S., Jebaraj, I., Romeo, O., and Krucker, S.: Circularly Polarized Type III Storms Observed with PSP, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14886, https://doi.org/10.5194/egusphere-egu25-14886, 2025.
