Session SWR1 - Solar Sources of Space Weather
Judith de Patoul, onsite (Royal Observatory of Belgium, Belgium), Hebe Cremades (Uni. Mendoza and CONICET, Argentina), Barbara Perri, onsite (KU Leuven, Belgium)
The Sun is our superstar, shaping the near-Earth space environment and driving our (space) climate and space weather. Flares, Coronal Mass Ejections (CMEs), associated shock waves and Solar Energetic Particles (SEPs) are the main sources of major space weather disturbances at Earth and other planets. The strongest events originate from large, magnetically complex active regions. In addition, stealth CMEs and high-speed streams emanating from coronal holes can also unleash medium-sized storms.
In this session, we invite contributions on all topics relating to the build-up, origin, triggering and early dynamics of solar eruptive events, that provide us with a better characterization, diagnostics and deeper physical understanding of the solar sources of space weather events, which is key to improve space weather predictions. This covers both observational and modelling approaches, as well as new techniques and studies on the conditions for extreme events.
Thursday October 27, 08:30 - 13:30, Poster Area
Thursday October 27, 14:15 - 15:30, Water Hall
Friday October 28, 11:30 - 12:45, Water Hall
14:15 Investigating the Evolution of Flux Rope Properties in the Low Corona via Data-Driven Modelling on the Example of AR12473 Wagner, A et al. Oral
Andreas Wagner, Emilia K. J. Kilpua, Daniel J. Price, Jens Pomoell, Anshu Kumari, Farhad Daei, Ranadeep Sarkar
Department of Physics, University of Helsinki
The early evolution of erupting solar flux ropes (FR) is crucial for forecasting their space weather impacts. We therefore make use of the data-driven and time-dependent magnetofrictional model (TMFM) to simulate a FR through this early eruption phase. We develop a semi-automatized FR extraction algorithm to track the FR through the simulation domain and to calculate its various properties and investigate its temporal evolution. The tracking method is based on the twist parameter \textit{Tw}. We apply the extraction algorithm on a TMFM simulation of the active region AR12473 and track the movement of the FR footpoints and calculate the evolution of the magnetic flux. The footpoint movement is compared to the movement of EUV core dimmings from SDO's AIA instrument in the 211~{\AA} range and to the movement of brightenings in UV at 1600~{\AA} (also SDO AIA). We also perform a relaxation run, where we stop the driving of the TMFM and evolve the system with a zero-beta MHD approach instead. Comparison shows that the movement of modelled FR footpoints for both the TMFM and the MHD relaxation matches well with the movement of observationally derived features: In all investigated cases the footpoints or observational features receded from each other. We also find that the positive polarity footpoint exhibits a more dynamic evolution. The computed and experimentally derived toroidal fluxes through the footpoints show however the opposite trends: The computed fluxes show mainly a rising trend, while from the dimming analysis for this particular active region, we find a dominantly declining trend.
14:30 Partially Open Fields and Solar Eruptions Linker, J et al. Oral
Jon A. Linker[1], Cooper Downs[1], Ronald M. Caplan[1], Tibor Torok[1], Viacheslav Titov[1], Pete Riley[1]
[1]Predictive Science Inc. San Diego, CA USA
The solar magnetic field is recognized to be the energy source for major solar eruptions, such as flares and coronal mass ejections (CMEs). Specifically, it is believed to be the release of the free magnetic energy (energy above the potential field state) stored in the field prior to eruption. A key question for both predicting future eruptions and estimating their possible magnitude is, what is the bound to this energy? The Aly-Sturrock theorem shows that the energy of a fully force-free field cannot exceed the energy of the so-called open field. If the theorem holds, this places an upper limit on the amount of free energy that can be stored. The energy of a closely related field, the partially open field (POF), can in principle place a much tighter constraint than the energy of the fully open field. Unlike the fully open field, it is difficult to exactly calculate the POF for generalized configurations. Recently, we have developed techniques for estimating the energy of this field (POFE) for realistic solar fields (based on magnetograms). The estimates are based on potential-field like solves that we can compute rapidly using POT3D (Caplan et al. ApJ, 915, 2021). In this presentation, we demonstrate the application of the method to solar active regions that produced major solar eruptions, and we test the validity of the method to predict maximum energy release using MHD simulations of selected cases. We discuss the possible future space weather applications of the method. Research supported by NASA and NSF.
14:45 Coronal Waves Observed in EUV Images and Solar Energetic Particles Nitta, N et al. Oral
Nariaki Nitta, Neal Hurlburt, Steve Petrinec
Lockheed Martin Advanced Technology Center
Low-coronal signatures of coronal mass ejections (CMEs) include phenomena often referred to as coronal dimmings and EUV waves. Although EUV images from SDO/AIA significantly advanced our understanding of these phenomena, few studies have addressed a possible variety of their relationship with CMEs. Observationally, we note extended and fast CMEs that have a wide range of the relative strengths of dimmings and EUV waves, which may contain important information as to the initiation and early evolution of eruptions. There are also strong EUV waves with shallow dimmings that result in only a marginal CME in coronagraph data. In this study, we revisit the relation of EUV waves with SEPs both in ions and electrons. Systematic studies of SEP timings and EUV wave propagations were conducted for solar cycle 23 events, for which observations of EUV waves were compromised. In the SDO era, several studies have reached different conclusions as to the relevance of EUV waves in SEP events. The interest in recent years has been shifted to higher-order problems, for example, the relation of SEP intensities with the parameters of CME-driven shock waves as calculated with combinations of geometric fitting of CME fronts and MHD models for the ambient solar wind. We instead evaluate the possible role of EUV waves in producing and spreading SEPs to wide longitudes, comparing EUV and coronagraph images with SEP data at L1 and STEREO. We also ask whether and how the behaviors of EUV waves and coronal dimmings may affect SEP properties such as the electron-to-proton ratio, rise time, spectrum, composition, etc.
15:00 Operational flare forecasting with video-based deep learning Piana, M et al. Oral
Michele Piana[1], Sabrina Guastavino[1], Francesco Marchetti[2], Cristina Campi[1], Federico Benvenuto[1]
[1] MIDA, Dipartimento di Matematica, Università di Genova, Genova, Italy, [2] Dipartimento di Matematica, Università di Padova, Padova, Italy
From the machine/deep learning perspective, the design and implementation of algorithms for operational flare prediction is still an open issue and, even more importantly, there is still little discussion about how to develop neural networks for real-time flare forecasting and how to perform their validation and verification. This talk illustrates a convolutional neural network fed by means of videos of magnetograms and optimized by means of a training set generated according to a paradigm that accounts for the part of the solar cycle progression where the prediction is requested. The talk discusses results concerning the prediction of solar flaring storms occurred during solar cycle 24
15:15 A DEFT way to forecast solar flares Krista, L et al. Oral
Larisza Krista[1], Matthew Chih[2]
[1]University of Colorado/CIRES, NOAA/NCEI; [2]Marietta College
Solar flares have been linked to some of the most significant space weather hazards at Earth. These hazards, including radio blackouts and energetic particle events, can start just minutes after the flare onset. Therefore, it is of great importance to identify and predict flare events. The Detection and EUV Flare Tracking (DEFT) tool allows us to identify flare signatures and their precursors using high spatial and temporal resolution extreme-ultraviolet (EUV) solar observations. The unique advantage of DEFT is its ability to identify small but significant EUV intensity changes that may lead to solar eruptions. Furthermore, the tool can identify the location of the disturbances and distinguish events occurring at the same time in multiple locations. The algorithm analyzes high temporal cadence observations obtained from the Solar Ultraviolet Imager instrument aboard the GOES-R satellite. In a study of 61 flares of various magnitudes observed in 2017, the "main" EUV flare signatures (those closest in time to the X-ray start time) were identified on average 6 minutes early. The "precursor" EUV signatures (second-closest EUV signatures to the X-ray start time) appeared on average 14 minutes early. Our next goal is to develop an operational version of DEFT and to simulate and test its real-time use. A fully operational DEFT has the potential to significantly improve space weather forecast times.
16:30 Deciphering the evolution of pre-eruptive CME structures during the slow rise Xing, C et al. Oral
Chen Xing[1,2], Guillaume Aulanier[1,3], Xin Cheng[2,4], Mingde Ding[2]
[1]Laboratoire de Physique des Plasmas (LPP), École Polytechnique, IP Paris, Sorbonne Université, CNRS, Observatoire de Paris, Université PSL, Université Paris Saclay, Paris, France; [2]School of Astronomy and Space Science, Nanjing University, Nanjing, China; [3]Rosseland Centre for Solar Physics (RoCS), Universitetet i Olso, Oslo, Norway; [4]Max Planck Institute for Solar System Research, Göttingen 37077, Germany
Coronal mass ejections (CME), the largest scale eruptions of plasmas in the solar corona, have great impact on the variation of the space weather. Many observations show that the pre-eruptive CME structure slowly rises and is significantly heated when approaching the onset of the eruption. However, the mechanisms behind these phenomena are still puzzling. In this work, we aim to explore these mechanisms by combing observations and numerical simulations. Based on the observation of an eruptive event, we find that a moderate magnetic reconnection, evidenced by the weak thermal-dominated hard X-ray emission, occurs before the eruption. This reconnection forms the hot M-shaped threads and cusp-shaped loops, and contributes to the slow rise and the heating of the pre-eruptive CME structure. In a zero-beta three-dimensional (3D) magnetohydrodynamic (MHD) simulation performed by OHM, we find similar M-shaped field lines in the pre-eruptive CME flux rope. Further analysis demonstrates that the Lorentz force within the flux rope, especially its tension component, drives the slow rise. We also perform a thermal 3D MHD simulation of a pre-eruptive CME structure by MPI-AMRVAC, successfully reproducing the slow rise and the heating phenomena. In this more complex simulation, we are able to further study the effects of instability, magnetic reconnection, thermal pressure gradient and gravity on the slow rise, and also the contributions of resistive dissipation, viscous dissipation, compression and thermal conduction to the heating. All of the above results will give us a better understanding of how the pre-eruptive CME structure gradually transitions from a quasi-static state to an explosive state, and will open a new window to predicting the CME eruption and the associated space weather.
16:45 Multi-wavelength observations of filament eruptions. Wauters, L et al. Oral
Laurence Wauters, Marie Dominique
Royal Observatory of Belgium
Filament eruptions are very often associated to coronal mass ejections (CMEs) and sometimes to flares, which are both primary drivers for space weather. Depending on the situation, filament eruptions can show very different signatures in full-Sun irradiance time series, in particular in terms of the wavelengths in which they can be detected. We recently reported on observations of filament eruptions that cannot be seen in coronal wavelengths and are therefore not associated to any flare reported by GOES, while they show a clear signature in PROBA2/LYRA Lyman-alpha emission. In this presentation, we propose a more systematic analysis of observational characteristics in multiple wavelengths (SXR, 304 A, Lyman-alpha) of a set of filaments, and try to draw some conclusions about the underlying eruption mechanism.
17:00 Coronal dimmings - a proxy for the directivity of CMEs? Chikunova, G et al. Oral
Galina Chikunova[1], Tatiana Podladchikova[1], Karin Dissauer[2,3], Astrid Veronig[3,4], Mateja Dumbović[5], Manuela Temmer[3], Ewan Dickson[3]
[1]Skolkovo Institute of Science and Technology, Space Center, Russian Federation; [2]NorthWest Research Associates, Boulder, USA; [3]Institute of Physics, University of Graz, Graz, Austria; [4]Kanzelhohe Observatory for Solar and Environmental Research, University of Graz, Treffen, Austria; [5]Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kaciceva 26, HR-10000 Zagreb, Croatia
Coronal dimmings are regions in the solar corona that represent a sudden decrease of the coronal EUV and SXR emission, which is interpreted as a density depletion caused by the evacuation of plasma due to the CME eruption. This study presents a detailed analysis of the coronal dimming associated with the halo coronal mass ejection (CME)/filament eruption event on 2021 October 28. We aim to establish a relationship between the evolution of the dimming areas and the CME propagation direction. First, we define the dominant direction of the dimming propagation by separating the solar surface into sectors and tracking the cumulative dimming parameters (total area, brightness) within the defined sectors using SDO/AIA 193Å data. We also describe the importance of correcting the dimming area estimation by calculating the double integral over the surface. Second, we define the flux rope propagation direction during the early CME evolution. For that we perform 3D reconstructions of the eruptive filament, increasing in height from 150±2 to 295±2 Mm within 15 minutes. Using stereoscopic EUV data from SDO and STEREO-A, we derive the average velocity of the erupting filament at around 160 km/s. Our results reveal that orthogonal projections of the filament heights onto the solar surface are located in the sector of the dominant dimming growth. At the same time, the dimming morphology is in good agreement with the GCS reconstructions of the observed CME. These findings suggest that the evolution and morphology of dimmings may serve as an indicator of the early evolution of the CME/flux rope propagation direction even before the event is observed by coronagraphs along the Sun-Earth line. The information on CME propagation direction is a crucial parameter in Space Weather forecasting models. In particular, for Earth-directed CMEs, the dimming evolution might serve as valuable proxy-enhancing predictions.
17:15 Geo-effectiveness of Radio-loud and Radio-quiet Coronal Mass Ejections Kharayat, H et al. Oral
Hema Kharayat[1], Bhuwan Joshi[2], Ramesh Chandra[3]
[1]Indian Institute od Astrophysics, Bangalore, India; [2]Udaipur Solar Observatory, Physical Research laboratory, Udaipur, India; [3]DSB Campus, Kumaun University, Nainital, India
Coronal mass ejections (CMEs) largely influence the space weather and cause geomagnetic perturbations. Hence, the statistical studies pertaining to the occurrence of CMEs over the solar cycles and their consequence at the near-Earth region are extremely important. For an in-depth understanding, such studies need to be carried out considering various observational aspects of CMEs. With this motivation, here we present a statistical study of radio-loud (RL) and radio-quiet (RQ) CMEs during solar cycles 23 and 24. We also assess their geo-effectiveness and analyze their influence on cosmic ray intensity (CRI). The RL and RQ CMEs constitute 40% and 60% cases, respectively, of the total population of CMEs that arrive the near-Earth region at 1 AU. The mean speed of RL CMEs ($\approx$1170 km/s) was found to be significantly higher (almost twice) than the mean speed of RQ CMEs ($\approx$519 km/s) in the low corona while their speed became comparable ($\approx$536 km/s for RL and $\approx$452 km/s for RQ CMEs) at near-Earth region. The yearly-averaged speeds of Earth-reaching CMEs follow solar cycle variations. The CRI and geomagnetic Dst index are found to have good negative correlation with speed of Earth-reaching CMEs. RL CMEs were found to be more effective in producing CRI depressions and geomagnetic storms (GSs) in comparison to RQ CMEs; in about 70% cases RL CMEs produced CRI depression and GSs earlier than the RQ CMEs. Superposed epoch analysis suggests strongest depression in CRI occurs 2-5 days and 4-9 days after the onset of RL and RQ CMEs, respectively. Further, GS events show a time-lag of 1-5 days and 3-8 days, respectively, with respect to RL and RQ CMEs.
17:30 Is there a Dynamic Difference between Stealthy and Standard CMEs? Bemporad, A et al. Oral
Beili Ying[1,2], Alessandro Bemporad[3], Li Feng[1,2], Nariaki Nitta[4], Weiqun Gan[1,2]
[1]Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences,210023 Nanjing, China, [2]School of Astronomy and Space Science, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China, [3]INAF-Turin Astrophysical Observatory, via Osservatorio 20, 10025 Pino Torinese (TO), Italy, [4]Lockheed Martin Solar and Astrophysics Laboratory, Department A021S, Building 252, 3251 Hanover Street, Palo Alto, CA 94304, USA
Stealthy Coronal Mass Ejections (CMEs), lacking low coronal signatures, can result in significant geomagnetic storms. However, the mechanism of the stealthy CME is still highly debated. In this work, we investigate whether there is a dynamic difference between the stealthy and standard CMEs. This work selects seven stealthy and eight standard CMEs with slow speed. We obtain two-dimensional speed distributions of CMEs based on the cross-correlation method, rather than the unidimensional speed, and further acquire more accurate distributions and evolution of CME mechanical energies. Then we derive the CME driving powers and calculate the correlation between the driving powers and CME parameters (mass, average speed, and acceleration) for standard and stealthy CMEs, respectively. Besides, we quantitatively estimate CMEs' driving forces, including Lorentz forces and drag forces due to the ambient solar wind near the Sun. The results reveal that both the standard and stealthy CMEs are propelled by the combined action of the Lorentz force and drag force in the inner corona. The drag force is comparable with the Lorentz force. However, the impact of these two forces on the global expansion of the stealthy CMEs is significantly weaker than that of the standard CMEs.
11:30 Hemispheric sunspot numbers starting from 1876 and their use for solar cycle predictions Veronig, A et al. Oral
A. M. Veronig[1,2], T. Podladchikova[3], S. Jain[3], W. Pötzi[2], F. Clette[4], O. Sutyrina[3], M. Dumbovic[5]
[1]Institute of Physics, University of Graz, Austria; [2]Kanzelhöhe Observatory for Solar and Environmental Research, University of Graz, Austria; [3]Skolkovo Institute of Science and Technology, Moscow, Russia; [4]World Data Center SILSO, Royal Observatory of Belgium, Brussels, Belgium; [5]Hvar Observatory, University of Zagreb, Croatia
Solar cycle predictions are a key parameter for medium- and long-term predictions of our space weather. It is well established that the solar cycle shows significant north-south asymmetries for various features and indicators of solar activity, which suggests some decoupling between the two hemispheres over the solar cycle evolution, in agreement with dynamo theories. However, for the most important solar activity index, the sunspot numbers, only limited data on their hemispheric distribution was available. We created a continuous series of daily and monthly hemispheric sunspot numbers (HSNs) from 1874 to 2020 (Veronig et al. 2021), which can be seamlessly expanded in the future with the HSNs provided by SILSO. The HSNs are reconstructed from the hemispheric Greenwich sunspot area data, validated against the direct HSN data available since 1945, and are consistent with the newly calibrated International Sunspot Numbers (ISN; Clette et al., 2014). The data are provided in the form of a tabulated catalogue of daily, monthly mean, and 13-month smoothed monthly mean HSNs for the time range 1874-2020, fully covering solar cycles 12 to 24 (https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/652/A56). Relating the ISN and HSN peak growth rates during the cycle rise phase with the cycle amplitude reveals higher correlations when considering the two hemispheres individually, with r ≈ 0.9. In a subsequent study, Podladchikova et al. (2022) developed a solar cycle amplitude prediction method based on the maximal growth rate of sunspot activity, and demonstrated that separate consideration of the two hemispheres using the HSN provides more accurate predictions than that using the total sunspot numbers.
11:45 Differences in physical properties of coronal hole and quiet Sun coronal bright points and their ALMA counterparts Matković, F et al. Oral
Filip Matković[1], Roman Brajša[1], Manuela Temmer[2], Stephan G. Heinemann[3], Hans G. Ludwig[4], Steven H. Saar[5], Caius L. Selhorst[6], Ivica Skokić[1], Davor Sudar[1]
[1]Hvar Observatory, Faculty of Geodesy, University of Zagreb, Croatia; [2]Institute of Physics, University of Graz, Austria; [3]Max-Planck-Institut für Sonnensystemforschung, Germany; [4]Landessternwarte, Zentrum für Astronomie der Universität Heidelberg, Germany; [5]Harvard-Smithsonian Center for Astrophysics, USA; [6]NAT - Núcleo de Astrofísica, Universidade Cidade de São Paulo, Brazil
Coronal bright points (CBPs) are a fundamental class of solar activity phenomenon. They represent a set of small-scale loops in the low corona that have an enhanced ultraviolet (UV)/extreme-ultraviolet (EUV) and X-ray emissions. CBPs are found in- and outside of coronal holes (CHs), and with that can be used as proxy to investigate low coronal characteristics of CHs, especially their magnetic field topology. As CHs are the primary sources of high-speed solar wind streams, CBPs might serve as important input for solar wind models. Using EUV 193 Å and magnetogram data obtained by Solar Dynamics Observatory (SDO) and full-disk Band 6 (λ = 1.21 mm) radio data by Atacama Large Millimeter/submillimeter Array (ALMA), we report measurements of the intensity and area of coronal bright points within five CHs observed at different times near the centre of the solar disk and in the quiet Sun (QS) regions. CBPs were identified based on EUV and magnetogram data and measurements of the mean intensity and area of the detected CBPs were conducted for both SDO EUV and ALMA Band 6 images. Then, an unequal variances t-test was conducted on randomly chosen CBP samples using a bootstrap technique to determine if CH and QS CBPs show any differences in the measured physical properties. Statistical analysis of the measured physical properties revealed that CBPs within CHs have on average a significantly lower mean intensity as well as a lower area than the QS CBPs. This was the case for both SDO and ALMA data. Future study will follow the evolution of the physical properties (intensity, morphology and magnetic field) of both CBPs and CHs in order to determine the true causes of the observed CBP differences with a focus on the magnetic field and morphology of the CHs as one of those possible causes.
12:00 Addressing Boundary Conditions of Coronal Models Brchnelova, M et al. Oral
Michaela Brchnelova[1], Blazej Kuzma[1], Barbara Perri[1], Stefaan Poedts[1,2]
[1]KU Leuven; [2]University of Maria Curie-Sklodowska
The accuracy of space weather forecasting tools such as EUHFORIA is only as good as the accuracy of the prescribed input data on the inner boundary, generally coming from coronal models. Thus, to improve the reliability and performance of space weather forecasting, having more accurate coronal models based on 3D MHD instead of just PFSS extrapolation is of essence. To that end, we have recently developed a coronal model COCONUT that is heavily parallelised and relies on an implicit numerical scheme. As a result, it can converge within a couple of hours even for the cases of solar maxima, which makes it suitable even for operational runs and real-time solar weather forecasting. Even such fast-converging codes are, however, only useful if they are sufficiently physically accurate. In practice, with the MHD formulation, the physicality of such simulations is dictated by the non-ideal source term and the boundary conditions. The former has been discussed rather extensively in literature on coronal models; primarily when it comes to the methods to approximate the coronal heating term and produce a bimodal solar wind. The latter is, however, usually discussed in far lesser detail, even though it can influence the simulation results just as much. On the inner boundary of coronal simulations, we generally prescribe homogeneous conditions everywhere, which would be representative of some reference state in the lower corona. This is, however, a very strong approximation, which can be very inaccurate especially in cases of solar maxima, where many active regions and coronal holes are present. Especially in cases of solar maxima, without pre-processing of the magnetogram data, while running COCONUT, we have often seen instability developing over these boundary regions leading to locally negative temperatures and thus indicating that this boundary condition was indeed unphysical. Here, we investigate other methods to formulate the state on the inner boundary to better represent the real physical behavior. We also briefly touch upon the outer boundary condition. Even though this is a supersonic boundary and thus only an extrapolation of hydrodynamic states is required, we will show that the way in which the extrapolation is carried out can still affect the formation of structures within the domain and more importantly - the data that is transferred to the heliospheric model.
12:15 Advanced models of the solar wind, inner corona and heliosphere Brun, A et al. Oral
A.S. Brun[1], V. Réville[2], B. Perri[1], A. Strugarek[1], R. Pinto[1], A. Finley[1], S. Parenti[3]
[1]DAp-AIM, CEA Paris-Saclay, France; [2]IRAP, France; [3]IAS, France
We perform 3D MHD simulations of the solar wind and inner corona and heliosphere for various recent dates using the Wind Predict-AW model. We confront their results to Solar Orbiter and Parker Solar Probe data, both using in situ and remote sensing observations.Using realistic data driven boundary conditions for the solar magnetic field, we compute the thermal, velocity and magnetic states of the solar wind and inner corona. We find a relatively good quantitative agreement when we include an Alfven wave and realistic heat transfer treatment. In quiet phases (2018-2019) this is enough to reproduce coronal holes and emissivity maps. In particular, real vs synthetic White light, EUV and X-ray images comparison are useful tools to calibrate the models. In-situ properties are also globally well reproduced. When active regions are present in more recent periods (2021-2022), a better treatment of the chromosphere is needed to reproduce these bright regions in EUV as well as other large scale features in the solar corona and wind. such improved models allows us to reproduce the dynamical states of the inner heliosphere and are key for space weather forecasting.
12:30 STORMS' Magnetic Connectivity and Shock Forecasting Tools at H.ESC Rouillard, A et al. Oral
Rouillard, A.P., Dalmasse, K., Kouloumvakos, A., Indurain, M., Poirier, N., Pinto, R., Alexandre, M.
We will first present recent developments of the Magnetic Connectivity Tool that provides continuous forecasts of how planets and spacecraft situated in the inner heliosphere (<2AU) connect magnetically to the corona and photosphere. We will illustrate how this tool is currently used for Solar Orbiter' science operations and how it is interfaced with other tools developed by the European Heliophysics community. In a second part, we will show the Shock-SEP Forecasting tool exploits the output of the Magnetic Connectivity Tool and other assets to provide forecasts of the evolution of shock waves and solar energetic particle events.
1 The pre-eruptive conditions and post-eruptive consequences of homologous compact major eruptive flares Sahu, S et al. Poster
Suraj Sahu[1], Bhuwan Joshi[2], Alphonse C. Sterling[3], Prabir K. Mitra[4], Ronald L. Moore[5]
[1]Physical Research Laboratory, [2]Physical Research Laboratory, [3]NASA/Marshall Space Flight Center, [4]Physical Research Laboratory, [5]University of Alabama in Huntsville
It is often observed that the Sun produces repetitive coronal mass ejections (CMEs) with similar morphological structures from the same source region within a short time span. This kind of CMEs are known as homologous CMEs and their occurrence is majorly controlled by the storage of free magnetic energy in the active region corona. The stored energy is catastrophically released during flare accompanied by successful eruption of plasma material, which is ultimately observed as CME in the coronagraphic images. Therefore, it is important to study homologous flare-CME events to better understand their correlation in terms of sustained energy build-up in the corona. In our ongoing study, we select three homologous flare-CME events of successively increasing flaring intensities. We analyze the detailed evolution of the photospheric line-of-sight magnetogram from ≈1 day before the first event and encompassing all the three events. Our observations reveal episodic phases of emergence and cancellation of magnetic flux in and around the flaring region. In view of this, our observations strongly support the idea of 'tether-cutting' model as a plausible triggering mechanism of the eruptions. Interestingly, we note that the successive eruptions led to broad CMEs (angular width ≈100° to 360°), in spite of their origin from compact eruption source site. We investigate this apparent inconsistency and propose a generalized scenario of 'magnetic-arch-blowout' mechanism, which satisfactorily explains the observed phenomena.
2 An Investigation of the Influence of Solar Activities Variability on Earth's Climate Change Oloruntola, R et al. Poster
Racheal Foluke Oloruntola[1], Babatunde Adebo[2], Nurudeen Bakare[3], Aanuoluwapo Akinfoyeku[4]
[1]Physics Unit, Department of Science Laboratory Technology, Federal College of Animal Health and Production Technology Moor Plantation Ibadan, Department of Physics, Lead City University Ibadan; [2]Department of Physics, Lead City University Ibadan; [3]Olusegun Agagu University of Science and Technology Okitipupa, Ondo State Nigeria; [4]Physics Unit, Department of Science Laboratory Technology, Federal College of Animal Health and Production Technology Moor Plantation Ibadan
This study investigated the influence of solar activities variability on Earth's climate change. Statistical analysis were performed on the Sunspot (R) number, solar radio flux (F10.7 (sfu)) and sea surface temperature (SST) obtained from NSSDCs OMNI web service htpps://nssds.gsfc.nasa.gov/omniweb and Third Hadley Centre Sea Surface temperature data set (HADSST3) respectively. Analytically, the sunspot number was used to determine the correlation between the increase in sunspot number and the sea surface temperature that has been one of the basic indices for the study of Earth's climate change. Likewise, the F10.7 (sfu) was used to classify the intensity of solar activity. The result shows that the sunspot number varies with the sun activities and the increase in the number of sun spot has little effect on the sea surface temperature, however, the long term effect of the increase in the sunspot number may have significant effect on the climate change. We therefore concluded that the variability in the solar activities leading to the increase and decrease in the sunspot number may contribute to the increase in the sea surface temperature which could have adverse effect on Earth's climatic condition. Keywords: Solar activities; climate change; Sunspot number; Intensity; solar radio flux.
3 Coronal dimmings as early indicators of CME propagation direction Jain, S et al. Poster
Shantanu Jain[1], Galina Chikunova[1], Tatiana Podladchikova[1], Karin Dissauer[2], Astrid M. Veronig[3,4]
[1]Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, bld. 1, Moscow 121205, Russia; [2]NorthWest Research Associates, 3380 Mitchell Lane, Boulder 80301, CO, USA; [3]University of Graz, Institute of Physics, Universitätsplatz 5, 8010 Graz, Austria; [4]University of Graz, Kanzelhöhe Observatory for Solar and Environmental Research, Kanzelhöhe 19, 9521 Treffen, Austria
Coronal mass ejections (CMEs) are large-scale structures of magnetized plasma erupting from the Sun that cause severe disturbances in Space Weather. However, the early evolution of CMEs, in particular Earth-directed ones, is difficult to trace with traditional coronagraphs and the estimation of CME properties is also challenging due to projections errors. The most distinct phenomena associated with CMEs are coronal dimmings, localized regions of reduced emission in the extreme-ultraviolet (EUV) and soft X-rays, formed due to mass loss and CME expansion low in the corona. In this study we present the methods of using dimmings as an early indicator of the CME propagation direction. We study the relationship between the evolution and morphology of dimmings and CMEs based on simulated CME/dimming observations (using a geometric CME cone model) for various sets or combinations of CME parameters (width, height, radial direction, deflection from radial direction). In addition we perform detailed case studies of well-observed dimmings and observed CMEs to establish the relationship between them. The results obtained are of particular interest for Earth-directed CMEs, as they provide information on the occurrence and early evolution of the CME before the event is observed by coronagraphs along the Sun-Earth line.
4 Application of different flare predictor proxies in 3D to increase the prediction time windows Korsos, M et al. Poster
Marianna Korsos
University of Catania
First, we address pre-flare behavioural patterns of the solar active regions by focusing on their evolution via different morphological parameters (e.g. magnetic helicity flux, weighted horizontal magnetic field gradient, sum of the horizontal magnetic gradient .. ) in 3D via PF, LFF, and NLFF extrapolation data. Next, we address how these morphological parameters can be generalised and applied in 3D suitable to model the lower solar atmosphere. We will demonstrate how can we even further increase the capability of the flare onset time prediction in the solar atmosphere with our approach using a 3D extension of the method.
5 Impact of photospheric magnetic field maps on the prevision of heliospheric structures and CME propagation Perri, B et al. Poster
Barbara Perri [1,2], Gabriel Aulanier [3], Michaela Brchnelova[1], Blazej Kuzma [1], Tinatin Baratashvili[1], Fan Zhang [1], Andrea Lani [1], Stefaan Poedts [1,4]
[1] CMPA, KU Leuven, Leuven, Belgium, [2] DAP, CEA AIM, Université Paris-Saclay, France [3], Centrale Marseille, Marseille, France [4], Institute of Physics, University of Maria Curie-Sklodowska, Lublin, Poland
Space weather has the difficult task to try to anticipate the propagation of eruptive events such as coronal mass ejections (CMEs) in order to assess their possible impact on the Earth's space environment. This requires an accurate description of the background in which CMEs propagate, mainly the continuum ejecta of particles that is the solar wind and the dynamo-generated heliospheric magnetic field. The approach used by the EUHFORIA 2.0 project is to use a chain of models, taking advantage of existing codes to combine their strengths through numerical coupling across the heliosphere. The first step of this chain is the data-driven modelling of the inner corona, from photosphere measurements up until 0.1 AU, and it proves especially critical as it serves as boundary condition for the rest of the models. Coronal models nowadays have a large variety of magnetic maps they can use as input (ex: GONG, ADAPT, HMI…), but it is not very clear what are the benefits or drawbacks for each type of map, and what impact they have on space-weather forecasting. We will provide here insights on how to connect the photospheric magnetic measurements with observations and models, both at 0.1 and 1 AU. First we will present our results for minimum of activity using our new MHD implicit coronal model COCONUT. We test 20 maps for the same date, and by comparing our simulations with remote-sensing observations, we show that especially the modelling of the solar poles is critical for the magnetic connectivity as well as the coronal hole positions. Then we move on to maximum of activity to assess the impact of magnetic maps on CME propagation. We take the well-studied case of the 12th of July 2012 using a spheromak CME in EUHFORIA, and show that by just changing the magnetic map at the solar surface, we can improve significantly the prevision of the shock arrival at Earth. 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).
6 Exploring the formation of the cantle-shaped flare loops Xing, C et al. Poster
Chen Xing[1,2], Guillaume Aulanier[1,3], Jaroslav Dudík[4]
[1]Laboratoire de Physique des Plasmas (LPP), École Polytechnique, IP Paris, Sorbonne Université, CNRS, Observatoire de Paris, Université PSL, Université Paris Saclay, Paris, France; [2]School of Astronomy and Space Science, Nanjing University, Nanjing, China; [3]Rosseland Centre for Solar Physics (RoCS), Universitetet i Olso, Oslo, Norway; [4]Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 251 65 Ond\v{r}ejov, Czech Republic
The flare arcades/loops are low-lying structures formed by the magnetic reconnection during the coronal mass ejection (CME) eruption. Lörinčík et al. (2021) showed that the flare arcades take the shape of a saddle for the cases they studied. The flare loops at the two ends of the arcade, which are longer and higher than those in the middle, make up the cantle of the saddle. Detailed observations imply that the formation of these cantle-shaped flare loops is most likely related to a magnetic reconnection between the flux rope and the inclined arcade, but it needs to be supported by more evidence. In this work, we aim to explore the formation process of the cantle-shaped flare loops by analyzing a three-dimensional (3D) magnetohydrodynamic (MHD) simulation performed by OHM. During the CME eruption, the reconnection, named "ar-rf reconnection", occurs between the flux rope and the shear arcade, producing the new flux rope and the flare loop. Further analysis shows that the shear arcades continuously shrink to flare loops during this reconnection with their footpoints slipping along the flare ribbon. The flare loops at different stages of this process make up a shape of cantle, strongly supporting that the cantle-shaped flare loops in the observation are dynamic structures formed by the "ar-rf reconnection". In addition, these results reveal more details of the "ar-rf reconnection" that probably occurs on the legs of the CME/interplanetary CME (ICME), and thus help us better understand the evolution of ICMEs that may affect the space weather.
7 Progress on the GOES High cadence Operational Total Irradiance project Snow, M et al. Poster
Martin Snow[1,2,3], Steven Penton[2], Stephane Beland[2], Odele Coddington[2], Don Woodraska[2]
[1] South African National Space Agency, [2] University of Colorado Boulder LASP, [3] University of the Western Cape
The Geostationary Operational Environmental Satellites (GOES-R) series includes the Extreme ultraviolet and X-ray Irradiance Sensors (EXIS). Two measurements from EXIS include the Magnesium II index at 280 nm and a broadband visible light measurement from the Solar Position Sensor (SPS). Both of these observations measure solar irradiance at high cadence, and they can be used to create a model of the full spectrum. The NRLSSI model (Coddington et al. 2016) uses two components to model the spectrum: the facular brightening derived from MgII, and the sunspot darkening from ground-based observations. Our project replaces the ground-based sunspot observations with the SPS measurements cross-calibrated to space-based Total Solar Irradiance measurements. We are in the second year of funding and have completed the calibration of the SPS and are now in the process of computing the full spectrum. We plan to produce the full spectrum on 3-second cadence for space weather applications.
8 IONOSPHERIC DISTURBANCES PRODUCED BY SOLAR WIND VARIATIONS USING VERTICAL TOTAL ELECTRON CONTENT Castano, J et al. Poster
Juan Manuel Castaño [1] and Amalia Margarita Meza [1]
MAGGIA Laboratory (CONICET)
The solar wind has an important influence on magnetospheric convection, where variations in IMF and solar wind dynamic pressures (PSW) can change the magnetospheric electric field and affect the mid and low-latitude ionosphere through the penetration process. Huang et al. (2002) studied quasi-periodic ionospheric perturbations by Millstone Hill radar observations and they associated those perturbations with the penetration of magnetospheric electric fields. In our work, we study the variability of the ionosphere during different transient and oscillatory events in the IMF and solar wind dynamic pressure behaviors, using vertical total electron content (VTEC) obtained from GNSS measurements. The global coverage of GNSS observations allows us to analyze the degree of penetration of magnetospheric electric fields at different longitudes and latitudes by calculating the VTEC in permanent geodetic stations distributed globally. Our preliminary results show quasi-periodic variations in VTEC at permanent stations near Millstone Hill during the events analyzed. The ionospheric perturbations obtained are very similar to those obtained by radar measurements. Furthermore, we will implement different numerical tools to analyze the power spectrum behavior of the studied parameters, and the correlation between the oscillations present in the ionosphere with those observed in the solar wind pressure and the IMF.
9 The effects of the sympathetic CMEs on the strength of the geomagnetic storms Sabeha, H et al. Poster
Hadeer F. Sabeha[1], Alshaimaa Hassanin[1], Ayman M. Mahrous[2], Mohamed Elnawawy[1]
[1] Department of Astronomy, Space Science and Meteorology, Faculty of Science, Cairo University, Giza 12613, Egypt, [2] Department of Space Environment, Institute of Basic and Applied Sciences, Egypt-Japan University of Science and Technology, 21934, Alexandria, Egypt.
In this study we address the question whether the sympathetic coronal mass ejections (CMEs) have an impact on the physical properties of the geomagnetic storms. Three investigations through the solar cycle 23 and 24 are carried out for this study. SOHO Large Angle and Spectrometric Coronagraph (LASCO) have been used to remotely view and infer from in situ observations how successive CMEs interact. Unusual radio bursts frequently occur in the corona as a result of CME-CME interaction. Extreme changes in the physical values caused by the compression of one CME by another can cause powerful geomagnetic storms. Future studies of homologous CME may shed more light on this association.
10 MHD EUHFORIA simulations for geoeffectiveness predictions Schmieder, B et al. Poster
Brigitte Schmieder (1,2,3), Anwesha Maharana (1), Camilla Scolini (4,5), Giuseppe Prete (1), Antonio Niemela (1), Stefaan Poedts (1,6)
1 Centre for Mathematical Plasma Astrophysics, Dept. of Mathematics, KU Leuven, 3001 Leuven, Belgium 2 LESIA, Observatoire de Paris, 5 place Jules Janssen, 92190 Meudon, France 3 SUPA, School of Physics & Astronomy, University of Glasgow, G12 8QQ, UK 4 Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA 5 UCPAESS, University Corporation for Atmospheric Research, Boulder, CO 80301, USA 6 Institute of Physics, University of Maria Curie-Skłodowska, Pl. M. Curie-Skłodowskiej 5, 20-031 Lublin, Poland
It is important to develop MHD simulations based on data driven to understand how coronal mass ejections (CMEs) can propagate in the heliosphere. Parametric studies using the MHD EUHFORIA simulations are well developed and show the important parameters involved in the journey of CMEs, such as pressure balance, speed, density. However it is also important to analyse case studies of the Sun-Earth chain of events to clarify the reasons why these events were geoffective or not at the Earth and confirm the predictions. The first case concerns a very faint magnetic cloud observed at L1 between two co-rotating regions. It could be reconstructed by the EUHFORIA simulation following the solar observations of a faint and slow CME observed at the Sun. The second case study is a case which promised to be very geoeffective according to the magnetic helicity observed in the sigmoid on the disk. A detail study revealed that the source region was associated to two CMEs on September 2014, 8 and 10. Their interaction produced a negative Bz component, which lead to a Dst=-100 nT. On the other hand the predicted long Bz negative due to the helicity of the sigmoid was not observed at L1. The EUHFORIA tool shows that the CME should have rotated before 0.1au, distance where we inject the CME in the preconditioned background solar wind. 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)
11 Modelling dynamical processes in the lower solar atmosphere with an ion-neutral two-fluid model Zhang, F et al. Poster
Fan Zhang[1], Andrea Lani[1], Stefaan Poedts[1,2]
[1] Centre for mathematical Plasma-Astrophysics, Department of Mathematics, KU Leuven, [2] Institute of Physics, University of Maria Curie-Skłodowska
The solar atmosphere, especially the lower solar atmosphere, is a complex plasma layer that undergoes various dynamical processes, and thus the plasma properties are changing drastically over time. Correspondingly, the energy transfer and conversion processes (and their efficiency) may vary along with the changing background plasma. Understanding these processes and the variation of the plasma properties is crucial for better understanding the physics of the overlying corona. In this work, we use an ion-neutral two-fluid model to numerically study the partially ionised plasmas that commonly exist in the lower solar atmosphere, especially in the chromosphere. In particular, MHD waves propagating in such a partially ionised plasma have been modelled, while taking into account the influences of the diverse background plasma conditions and magnetic fields. The energy conversion in the strong nonlinear processes (involving, e.g., magneto-acoustic shocks) occurring under different background conditions has been quantified, thus facilitating a deeper understanding of the dynamical chromospheric plasmas.
12 Sunspot and Interdecadal Space Weather Burst Lifetime Distributions Wanliss, J et al. Poster
James Wanliss[1], Ambaka LeGregam[1]
We examine interdecadal burst lifetime distribution functions of solar wind data and compare them with ground-based data reflective of space weather. The analysis yields clear power-law exponents of the lifetime probability distributions and similar scaling behavior for all the variables, including SYM-H, during solar minimum but significant differences during solar maximum, irrespective of activity thresholds. During solar maximum the scaling properties of the space weather signals are not purely a direct response to the scale free properties of the solar wind but are due to inherent properties of the magnetosphere.
14 Segmentation and Tracking of a Solar Eruption with Multiple Instruments Kozarev, K et al. Poster
Oleg Stepanyuk, Kamen Kozarev
Institute of Astronomy, Bulgarian Academy of Sciences
The shape and dynamics of coronal mass ejections (CMEs) varies significantly based on the instrument and wavelength used. This has led to significant debate about the proper definitions of CME/shock fronts, pile-up/compression regions, and cores observed in projection in optically thin vs. optically thin emission. As part of our work on advanced characterization of solar eruptions, we have performed observational analysis of the evolving shape and kinematics of a large-scale CME that occurred on May 7, 2021 on the eastern limb of the Sun as seen from the Earth. This is a rare eruption, because it was observed continuously by space- and ground-based instruments: consecutively by the Atmospheric Imaging Assembly (AIA) telescope suite on the Solar Dynamics Observatory (SDO) satellite, the ground-based COronal Solar Magnetism Observatory (COSMO) K-coronagraph (K-Cor) on Mauna Loa in Hawaiii, and the C2 and C3 telescopes of the Large Angle Solar Coronagraph (LASCO) on the Solar and Heliospheric Observatory (SoHO) satellite. Currently, the vast majority of eruptive events are only observable in AIA and LASCO, with a gap between the fields of view of these instruments. Applying our suite for segmentation and tracking Wavetrack successfully to three separate types of observations in this study boosts our confidence in its functionality and applicability. Its use allows us to directly overlay feature masks from separate instruments. It also allows us to provide answers to two important questions: 1. How does the CME shape evolve from the lower to the outer corona? 2. Is there a correspondence between the EUV wave and the CME front? Examination of the multi-instrument results suggests a strong correspondence between the CME features seen in the three instruments.
15 Solar weather products in the ESA SWE Portal from MEDOC, Université Paris-Saclay Buchlin, E et al. Poster
Éric Buchlin[1], Stéphane Caminade[1], Frédéric Auchère[1], Miho Janvier[1], Marc Dexet[1], Anthony Gréau[2], Khalil Ashkar[1]
[1] Université Paris-Saclay, CNRS, Institut d'Astrophysique Spatiale, 91405 Orsay Cedex, France, [2] HCube, 1 rue Bossuet, 92149 Clamart, France
In the framework of a contract between ESA's Space Weather Office and Université Paris-Saclay, MEDOC (CNRS / Université Paris-Saclay / CNES) has developed three products derived from SDO AIA and HMI data. These products are intended to support solar weather event analysis; they are integrated into the Solar Weather domain within ESA's SWE portal, and they include archive, and near-real time or nowcast and forecast components. These products are: (1) synchronous synoptic maps in UV and EUV, (2) maps of the thermal properties of the corona, and (3) maps of electric currents in Active Regions. Furthermore, during the current SWESNET activity, an additional product is being developed: (4) synchronous synoptic maps of the photospheric magnetic field. We will present these products and how they can be used within the network and by users of the portal.
16 Interaction of coronal mass ejections and the solar wind. A force analysis Talpeanu, D et al. Poster
Dana-Camelia Talpeanu [1], Stefaan Poedts [2,3], Elke D'Huys [1], Marilena Mierla [1,4], Ian G. Richardson [5,6]
[1] SIDC - Royal Observatory of Belgium (ROB), Belgium, [2] CmPA, Department of Mathematics, KU Leuven, Belgium, [3] Institute of Physics, University of Maria Curie-Skłodowska, Poland, [4] Institute of Geodynamics of the Romanian Academy, Romania, [5] Department of Astronomy, University of Maryland, USA, [6] Heliophysics Division, NASA Goddard Space Flight Center, USA
We obtained single and multiple solar eruptions through self-consistent magnetohydrodynamics numerical simulations, by means of shearing motions imposed at the inner boundary. Our goal is to thoroughly analyze the dynamics of these solar eruptions, as well as the occurrence of a stealth ejecta. We also assess how the propagation of these ejecta to Earth is affected by a different background solar wind. We calculated all the components of the forces contributing to the evolution of these consecutive coronal mass ejections simulated with the 2.5D module of the code MPI-AMRVAC. The thermal and magnetic pressure gradients and the magnetic tension were tracked in the equatorial plane throughout the propagation of the CMEs to Earth. We performed this analysis in order to analyze the 'CME-CME' and 'CME-background solar wind' interactions. These three force components were also used to explain the formation of the stealth ejecta and the plasma blobs in the trailing current sheet of solar eruptions. Furthermore, we try to understand the faster eruption of a CME when the same shearing speed is applied, but with a differently modelled background wind. We found that the slightly different coronal magnetic configuration and the large neighboring arcade contributed to this change in dynamics, emphasizing the strong influence of coronal parameters to solar eruption, and not just of photospheric ones. In the interplanetary space, the thermal pressure gradient revealed a shock in front of these slow eruptions, formed during their propagation to 1 AU. Finally, we noticed a double-peak structure in the magnetic pressure gradient also ahead of the front CME, that could indicate an effect of the triggering method onto the structure of the CMEs, and that a part of the adjacent streamer is ejected along with the CME.
17 Monitoring space weather with PROBA2/LYRA after 12 years in space Dammasch, I et al. Poster
Ingolf Dammasch [1], Marie Dominique [1]
[1] Royal Observatory of Belgium
The radiometer LYRA on board of the satellite PROBA2 consists of three similar units; one observes the Sun permanently, while the other two are spare units only used for limited campaigns. Each unit consists of four different UV-EUV sensors, of which two also respond to soft X-ray signals. While the nominal unit has heavily suffered from degradation concerning quiet-Sun signals, the monitoring of solar activity is still possible, because active-regions and flares mainly emit in the shortest wavelengths, which are less affected. This holds even more for the spare units. In this presentation, we quantify the impact of degradation on the performances of each unit of LYRA, considering separately the response to quiet-Sun, active regions and flares.
18 The COSPAR ISWAT Cluster S2: Ambient Solar Magnetic Field, Heating, and Spectral Irradiance Reiss, M et al. Poster
Martin A. Reiss [1,2], Charles N. Arge [3], Carl J. Henney [4], James A. Klimchuk [3], Jon A. Linker [5], Karin Muglach [3], Alexei A. Pevtsov [6], Rui F. Pinto [7,8], Samuel J. Schonfeld [9]
[1] Community Coordinated Modeling Center, NASA GSFC, Greenbelt, MD, USA, [2] Austrian Space Weather Office, Graz, Austria, [3] NASA Goddard Space Flight Center, Greenbelt, MD, USA, [4] Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, NM, USA, [5] Predictive Science Inc., USA, [6] National Solar Observatory, Boulder, CO, USA, [7] LDE3, CEA SAclay, DAp/AIM, University of Paris-Saclay, France, [8] IRAP, OMP/CNRS, CNES, University of Toulouse, France, [9] Institute for Scientific Research, Boston College, Newton, MA, USA
We present the activities of the Action Team Cluster S2: "Ambient Solar Magnetic Field, Heating and Spectral Irradiance" embedded in the COSPAR ISWAT initiative. The action teams in the ISWAT Cluster S2 address key problems in space weather research and forecasting. These problems include the construction of global solar magnetic field maps (Team S2-03), use of vector field synoptic maps for space weather modeling (Team S2-04), magnetic connectivity from the surface of the Sun to any point in interplanetary space (Team S2-05), location of open field lines along which solar wind flows accelerate to supersonic speeds (Team S2-01), and the solar spectral irradiance driving ionization and heating in the Earth's upper atmosphere (Teams S2-02 and S2-06). We present the objectives of the six action teams, summarize their current status, and discuss gaps that need to be addressed to drive progress in each area.
19 Using field line helicity to identify Space-Weather-important locations on the Sun Moraitis, K et al. Poster
Kostas Moraitis, Spiros Patsourakos, Alexander Nindos
Physics Department, University of Ioannina, Greece
Magnetic helicity - the geometrical quantity that describes the twist and writhe of individual magnetic field lines, and also, the intertwining of pairs of field lines - has an important physical meaning in the study of magnetized plasmas, as it is conserved in ideal magneto-hydrodynamics. In many cases however it is desirable to be able to identify the spatial locations where magnetic helicity is more important. A meaningful way to define such a density for magnetic helicity is through field line helicity, which, in solar conditions, is better expressed by relative field line helicity (RFLH). The first detailed study of RFLH in the solar active region 11158 revealed that it exhibits different morphology than other physical parameters, and thus, that it provides new information about the active region. Additionally, RFLH managed not only to reproduce the large decrease in the value of helicity during the X-class flare of the active region, but also to associate it with the flux rope that later erupted. Based on these results we highlight the necessary steps in identifying the solar locations of significant magnetic helicity. This task can provide crucial information for the conditions of the Sun, especially around eruptive events, and thus, it may facilitate the attempts to predict Space Weather.
20 Analysis of a productive active region from the beginning of the solar cycle 25 Dumitru, L et al. Poster
Liliana Dumitru, Cristian Danescu, Octavian Blagoi
The beginning of the solar cycle 25 exceeded the predictions being much more active. Several active regions that have developed high energy eruptions was recorded. Among these, active region (AR) 13078, which emerged on August 11, 2022 in the southern solar hemisphere, caught our attention. In this study, we followed the evolution of this region throughout its appearance on the solar disk. This active region developed multiple solar flares of C and M - class. We analyzed the M5.0 – class solar flare, produced on August 16, 2022 and captured by the Bucharest Solar Observatory.
21 Do pre-event conditions of the upper solar atmosphere differ for flare-imminent vs. flare-quiet active regions? Dissauer, K et al. Poster
Karin Dissauer[1], KD Leka[1,2], Graham Barnes[1], Eric L. Wagner[1]
[1]NorthWest Research Associates, 3380 Mitchell Lane, Boulder, CO 80301, USA; [2]Institute for Space-Earth Environmental Research, Nagoya University, Nagoya, Aichi 464-8601 JAPAN
Observational case studies of the solar chromosphere and corona reveal increased levels of magnetic reorganization, dynamics, and temperature variation prior to solar energetic events. Here, we investigate whether parameters describing these activities can differentiate a region that will imminently produce a solar flare from one that will not. We statistically analyze the coronal and chromospheric conditions prior to solar flares and during flare-quiet periods using a machine-learning ready dataset from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) recently created by NWRA. The AIA Active-Region Patches dataset (AARPs; Dissauer et al. 2022, ApJ under review) consists of region-targeted extractions of AIA time-series data in (extreme-) ultraviolet, matched to the HMI active region patches (HARPs), for most of solar cycle 24. Down-selection in the spatial domain is solely from full-disk to active-region size; the native spatial sampling is retained. Down-selection in the temporal domain is more severe (13min time intervals per hour at 72s cadence for 15:48-21:48 UT daily) yet allows for both short-lived features and longer-term trends to be evaluated. We characterize the pre-event dynamics and heating of the upper solar atmosphere using moment analysis through the kurtosis of brightness images and running-difference images. The temporal behavior is captured by the slope and intercept of a linear fit over a 6hr time-series of each parameter. The NWRA Classification Infrastructure (NCI), a well-established statistical classifier system based on Non-Parametric Discriminant Analysis, is applied to 32,000+ samples and four different flare-based event definitions to evaluate if parameters describing the pre-event conditions significantly differ for flare-imminent vs. flare-quiet populations. We find top Brier Skill Scores in the 0.07 – 0.33 range, True Skill Statistics in the 0.68 – 0.82 range (both depending on event definition), and Receiver Operating Characteristic Skill Scores above 0.8. Classification success using higher-order moments of running difference images indicates enhanced levels of short-lived brightenings in flare-imminent active regions. A high temperature ``memory'' of flare activity is also found. The 94 \AA filter data provides the most parameters with discriminating power with indications that it benefits from sampling multiple physical regimes.
22 Identifying solar features with Mathematical Morphology Bourgeois, S et al. Poster
Slava Bourgeois[1], Andreas Wagner[2], Teresa Barata[3], Robertus Erdélyi[4], Orlando Oliveira[5], Ricardo Gafeira[6]
[1]University of Coimbra, Instituto de Astrofisica e Ciências do Espaço, Physics Department, Portugal, [2]Solar Physics & Space Plasma Research Center (SP2RC), School of Mathematics and Statistics, University of Sheffield, UK
We seek to identify and classify solar features such as sunspots, facular regions, filaments, and pre-eruptive configurations of CMEs, whose behaviour influences solar activity in both the short and the long term, and therefore Space Climate and Space Weather (SW). On the one hand, sunspots and faculae are a good leading indicator of the variability and evolution of active regions where, generally, the most significant solar eruptions occur. We pinpoint both these features with an image analysis method based on set theory: Mathematical Morphology (MM). Indeed, MM is particularly well suited to the field of SW as it can recognize sharp edges and can deal with complex and irregular shapes. We apply MM algorithms to different types of images. Low-resolution images are taken from the observatories of Coimbra and Catania in the H-alpha continuum for identifying sunspots, and in the Ca II K3 line for faculae. Furthermore, high-resolution images are taken from the SDO satellite: HMI intensitygrams for sunspots and AIA 1600 Å data for faculae. Once these features are identified, we derive relevant properties such as their area and perimeter. Inside sunspots, the umbra can be separated from the penumbra, and the ratio of the umbra/penumbra's areas is investigated in order to probe the expansion of active regions over a solar activity cycle. On the other hand, one of the most important formation mechanisms of CMEs is the emergence of magnetic flux ropes. These are characterised by their twist, that is, the number of turns completed by the magnetic field lines around their common axis. In recent research, twist maps have been obtained and the central eruptive structure of flux ropes has been extracted with a numerical twist threshold. Here, we extract flux ropes with MM algorithms, and we seek to compare the two different methods, followed by a discussion on the findings.
23 The optimal sunspot number series: iterative construction Pavelkova, M et al. Poster
Michal Švanda[1], Martina Pavelková[1], Jiří Dvořák[2], Božena Solarová[1]
[1] Astronomical Instituteof the CAS, [2] Charles University
The relative number of sunspots (R) is widely used as a mean of quantifying THE solar activity. The construction of a single representative series of R is a delicate task which involves a combination of observation done by various observers. We propose a new iterative algorithm that allows to construct a target R series of a hypothetical stable observer. We show that our methodology provides us with results that are comparable with recent reconstructions of both sunspot number and group number while IT gives us also reconstruction uncertainties. We apply the methodology to a limited sample of observations by ČESLOPOL network and discuss its properties and limitations.