Session 1 - Solar Corona and Heliosphere: From Flares to CMEs and Interplanetary Shocks
Luciano Rodriguez (ROB), Jasmina Magdalenic (ROB), Emilia Kilpua (Univ of Helsinki), Sergio Dasso (IAFE/UBA)
Monday 5/11, 13:30-15:00 & 15:45-17:15
MTC 00.10, Large lecture room
Flares, Coronal Mass Ejections (CMEs) and associated shock waves are the topics of important research in the field of solar-terrestrial relations. Interplanetary Coronal Mass Ejections (ICMEs) and associated shock waves are the main drivers of geomagnetic storms. Flares can have an important impact (UV radiation, particles) on the Earth's atmosphere. Recent remote observations and modelling studies have shown that coronal mass ejections (CMEs) can drive shock waves very low in the solar corona, which, in turn, may produce significant fluxes of solar energetic particles (SEP). All these topics open a need for realistic data-driven simulations of CMEs and associated shocks with models like EUHFORIA or ENLIL.
In this session, we invite observational, theoretical, and modelling contributions that address the following topics: - Flares, the coronal dynamics of CME and shock waves and their related production of SEPs
- CME propagation in the heliosphere, the interaction of ICMEs with Earth and/or with other planets
- The link between CMEs and ICMEs.
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Talks : Time scheduleMonday November 5, 13:30 - 15:00, MTC 00.10, Large lecture room| 13:30 | Physics of Solar Storms: From Initiation to Heliospheric propagation | Vrsnak, B et al. | Invited Oral | | | Bojan Vrsnak[1] | | | [1]Hvar Observatory, Faculty of Geodesy, Kaciceva 26, 10000 Zagreb, Croatia | | | The term solar storm encompasses various physically related phenomena manifested as coronal mass ejections, flares, jets, global large amplitude waves and shocks, etc. Generally, solar storm is an explosive (a powerful) release of free energy contained in solar magnetic field structures, resulting in various forms of thermal and nonthermal processes and violent plasma flows, observed all over the electromagnetic spectrum from gamma-rays to radio waves.
Physical processes included in the energy release are characterized by a highly nonlinear behaviour and are governed by mechanisms that occur from plasma-kinetic scales to magnetohydrodynamical scales. Such a complex combination of various processes results in a variety of observational signatures characterized by millisecond-to-hourly scales. Most importantly, the effects of solar storms propagate into the heliosphere, dramatically affecting the space weather and causing various powerful processes in the geospace.
In this presentation, physical mechanisms and processes governing various stages and various features of solar storms are reviewed. The basic physical principles are applied to explain the initiation of the storm, the acceleration stage of the coronal mass ejection, the flare energy release, the physical relationship between the eruption and the flare, the formation and propagation of the eruption-driven shock wave, and finally, the heliospheric propagation of the eruption.
| | 14:00 | Diagnosing the Polar Field with EUV waves | Nitta, N et al. | Oral | | | Nariaki Nitta[1], Meng Jin[1,2] | | | [1]Lockheed Martin Advanced Technology Center, [2] SETI Institute | | | The Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) has observed at least several hundreds of large-scale coronal propagating fronts, simply referred to as EUV waves here. The list and the associated movies are publicly available at an AIA website. The propagation of an EUV wave clearly depends on the global corona. For example, they appear to be deflected at active regions and coronal hole boundaries that represent magnetic discontinuities. A remarkable observation is that different EUV waves show different patterns when approaching the solar polar regions, usually dominated by a coronal hole. Some EUV waves are seen to pass the polar region, while many others are seen to avoid it. This gives a range of the magnetic field strength of the polar region at the time of the EUV wave (as a fast mode MHD wave) with the assumed densities. Using the state-of-the-art MHD model, the Alfven Wave Solar Model (AWSoM), which is part of the University of Michigan Space Weather Modeling Framework (SWMF), we simulate a number of solar eruptions with EUV waves that show different patterns near the pole. The agreement of the simulations or the lack thereof with the observations will be used to evaluate how well the polar field is accommodated in synoptic magnetic maps used as the inner boundary for numerical modeling. We discuss how these comparisons vary with the solar cycle.
| | 14:15 | In-situ density of ICMEs versus CME 3D geometry and mass derived from remote sensing data | Temmer, M et al. | Oral | | | M. Temmer[1], L. Holzknecht[1], M. Dumbovic[1], B. Vrsnak[2], M. Rodari[1], A. Veronig[1] | | | [1]Institute of Physics, University of Graz, Austria, [2]Hvar Observatory, Faculty of Geodesy, University of Zagreb, Croatia | | | Using stereoscopic data from STEREO-SECCHI instruments COR1, and COR2, we derive the de-projected mass and its evolution for a sample of coronal mass ejections (CMEs). A significant mass increase can be found of the order of 2% – 6%, most prominent over the distance range 10Rs-15Rs. At a distance of about 20Rs it is assumed that the CME mass evolution more or less ceases and that a final mass is reached (cf., Bein et al., 2013). However, numerical studies reveal that there should be a significant increase of CME mass in interplanetary space (e.g., Lugaz et al., 2005). By applying the forward fitting model (Thernisien et al., 2006, 2009) on COR2 data, for some well observed events out of this sample, we obtain the geometry of the CMEs and their volume. Working under the assumption that the CME undergoes self-similar expansion and combining it with solar wind density assumptions, we will have a look at the CME mass development and derive the CME density (plasma composition of 90%H and 10%He) for the distance of 1AU. The results are compared to in-situ proton density data measured for the associated flux ropes. From this we may draw important conclusions on the possible CME mass increase in interplanetary space. | | 14:30 | Origin of the two co-temporal shock waves observed on September 27, 2012 | Jebaraj, I et al. | Oral | | | Immanuel Christopher Jebaraj[1][2], Jasmina Magdalenic[1], Camilla Scolini[1][2], Luciano Rodriguez[1], Stefaan Poedts[2], Vratislav Krupar[3][4][5], Jens Pomoell[6], Manuela Temmer[7] | | | [1]SIDC, Royal Observatory of Belgium, 1180 Uccle, Brussels, [2]CmPA, Department of Mathematics, KU Leuven, 3001 Leuven, Belgium, [3]Universities Space Research Association, Columbia, MD, USA, [4]NASA Goddard Space Flight Center, Greenbelt, MD, USA, [5]Institute of Atmospheric Physics CAS, Prague, Czech Republic, [6]University of Helsinki, Helsinki, Finland, [7]Institute of Physics/IGAM, University of Graz, Graz, Austria | | | Solar eruptive events such as Flares and CMEs (Coronal Mass Ejections) expel large amounts of energy and heat the ambient plasma, accelerate particles and generate waves. The CMEs and their associated shocks are the main drivers of space weather phenomena on Earth.
Herein we present the study of the CME/flare event on September 27, 2012. The full-Halo CME which drives a white light shock was observed by all three spacecraft STEREO A, STEREO B, and SOHO/LASCO. The GOES C3.1 flare and associated CME originated from NOAA AR 11577, which had a Beta-gamma configuration of its photospheric magnetic field in the moment of eruption. The associated radio event consisted of type II (signature of the shock) and type III (signature of fast electron beams propagating along open field lines) radio bursts. In this multi-wavelength study, we determined the physical characteristics of the CME and the CME-driven shock wave, in order to study the kinematics and understand their association.
To obtain the 3D propagation path of the shock wave, we perform radio triangulation using goniopolarimetric measurements from STEREO/WAVES and WIND/WAVES instruments. We perform data-driven modelling of the CME propagation using EUHFORIA flux rope model (EUropean Heliospheric FORecasting Information Asset) and validate the results by comparing with in-situ data. We demonstrate the need for 3D reconstructions in the studies of coronal shocks and associated CMEs.
| | 14:45 | Forbush decreases as signatures of Interplanetary Coronal Mass Ejections (ICMEs) | Dumbovic, M et al. | Oral | | | Mateja Dumbovic[1], Bojan Vrsnak[2], Bernd Heber[3], Manuela Temmer[1], Jingnan Guo[3], Christian Möstl[4], Reka Winslow[5], Noe Lugaz[5], Astrid Veronig[1], Anamarija Kirin[6], Martina Rodari[1,7], Lukas Holzknecht[1] | | | [1]Institute of Physics, University of Graz, Graz, Austria, [2]Hvar Observatory, Faculty of Geodesy, University of Zagreb, Zagreb, Croatia, [3]Institute of Experimental and Applied Physics, University of Kiel, Kiel, Germany, [4]Space Research Institute, Graz, Austria, [5]Institute for the Study of Earth, Ocean, and Space, University of New Hampshire, Durham, New Hampshire, USA, [6]Karlovac University of Applied Sciences, Karlovac, Croatia, [7]University of Milano-Bicocca, Milano, Italy | | | ICMEs are often associated with short-term reduction in galactic cosmic ray (GCR) flux, so-called Forbush decreases (FDs), which in turn can be regarded as one of the signatures of an ICME passage. Therefore, they can provide insight about ICMEs where/when in situ plasma and magnetic field measurements are not available. However, in order to use FDs as ICME signatures efficiently, it is important to understand the interaction of ICMEs with GCRs. We theoretically regard a textbook-example ICME which consists of the shock/sheath region and a magnetic ejecta producing a so-called two-step FD, where the first step is caused by the CME-driven shock and the second one by the magnetic ejecta. The shock/sheath region is magnetically connected to the ambient interplanetary space and characterized by disturbed plasma conditions and highly fluctuating magnetic field. We assume that the corresponding decrease is mainly caused by the magnetic mirror effect at the shock, where the shock thickness is much smaller than the GCR gyroradius, and the guiding-centre approximation and the magnetic-moment conservation are not applicable (Vrsnak et al., 2018, In prep.). On the other hand, the magnetic structure itself is not magnetically connected to the ambient plasma and is characterised by smooth magnetic field. Therefore, we assume an initially empty, closed magnetic structure which fills up slowly with GCRs as it propagates and expands in the interplanetary space (Dumbovic et al., 2018, ApJ). In both cases an analytical solution is obtained, and the corresponding FD can be related to a number of ICME properties, such as central magnetic field strength, expansion factor, shock strength and thickness. We analyze these theoretical considerations and apply them to selected events, where initial CME conditions are constrained using remote CME observation and 3D CME reconstruction. In addition, forward modelling and in situ measurements are used to analyse and constrain ICME evolution, utilizing a number of spacecraft and planetary observation, including those by the Radiation Assessment Detector aboard the Mars Rover Curiosity. This research has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 745782, and has been supported in part by Croatian Science Foundation under the project 6212 „Solar and Stellar Variability“. |
Monday November 5, 15:45 - 17:15, MTC 00.10, Large lecture room| 15:45 | What does "Realistic, Data-Driven Simulation of CMEs" Mean | De koning, C et al. | Oral | | | Curt A de Koning | | | University of Colorado / CIRES-SWPC | | | Realistic data-driven simulations of coronal mass ejections (CMEs) with magnetohydrodynamic (MHD) models like Enlil or EUHFORIA depend critically on realistic, data-driven boundary conditions. Using white-light coronagraph observations, which form the basis for CME-related boundary conditions, how well do we really know gross CME characteristics, such as speed, direction of propagation, width, and mass? And how big an impact does the variation in boundary conditions have on the MHD-forecast of ICME hit/miss and arrival time? In this presentation, we use multiple CME reconstruction techniques on several historic events to estimate appropriate uncertainty intervals for gross CME characteristics. Next, we use these uncertainty intervals to initiate an ensemble forecast for each event, which we compare to the historic SWPC forecast. The reconstruction techniques that we consider include geometric localization, forward modeling using the SWPC CME Analysis Tool, and simultaneous fitting of CME mass and direction of propagation. | | 16:00 | Observation-based Sun-to-Earth simulations of geo-effective Coronal Mass Ejections with EUHFORIA | Scolini, C et al. | Oral | | | Camilla Scolini[1,2], Francesco P. Zuccarello[1], Luciano Rodriguez[2], Stefaan Poedts[1], Marilena Mierla[2,3], Christine Verbeke[1], Jens Pomoell[4], Joachim Raeder[5], William D. Cramer[5] | | | [1]KU Leuven, Leuven, Belgium, [2]SIDC, Royal Observatory of Belgium, Uccle, Belgium
, [3]Institute of Geodynamics of the Romanian Academy, Bucharest, Romania, [4]University of Helsinki, Helsinki, Finland, [5]University of New Hampshire, NH, USA | | | Coronal Mass Ejections (CMEs) and their Interplanetary counterparts (ICMEs) are the primary source of space weather disturbances at Earth. The key ICME parameters responsible for driving strong geomagnetic storms are the dynamic pressure and the magnetic field Bz component at Earth, for which reliable predictions are not possible by means of traditional, over-simplified cone CME models. In order to overcome such limitations, the newly developed EUHFORIA heliospheric model has been recently integrated with a magnetised flux rope CME model that allows to model the IMF components associated to ICMEs to a higher degree of accuracy.
In this work we present a Sun-to-Earth comprehensive analysis of a selected set of Earth- directed CMEs, with the aim of testing the space weather predictive capabilities of the new flux rope CME model compared to those of an over-simplified cone CME model. We focus on the quantification of the prediction performances in terms of solar wind parameters at L1, and ICME geo-effectiveness estimated by means of global geomagnetic activity indices associated to the ICME-driven geomagnetic storm.
We first discuss the determination of the CME input parameters based on remote-sensing observations. For each event, we reconstruct the CME kinematic and geometric parameters by means of single- and multi- spacecraft reconstruction methods based on coronagraphic CME observations. The magnetic field-related parameters of the flux ropes are estimated based on imaging observations of the photospheric and low coronal source region of the eruption. We then simulate the events with EUHFORIA, using both a cone and a flux-rope CME model in order to compare the effect of the different CME kinematical and magnetic input parameters on simulation results at L1. We compare simulation outputs with in-situ observations of the ICMEs and we use them as input for the prediction of global geomagnetic activity indices, comparing our predictions with actual data records. We quantify the forecasting capabilities of such kind of approach and we discuss its future improvements. | | 16:15 | Multipoint study of an Earth-impacting CME erupting from the solar limb | Palmerio, E et al. | Oral | | | Erika Palmerio[1], Camilla Scolini[2], Luciano Rodriguez[3], Matthew West[3], Simon Good[1], Marilena Mierla[3] | | | [1]University of Helsinki, Helsinki, Finland, [2]KU Leuven, Leuven, Belgium, [3]Royal Observatory of Belgium, Brussels, Belgium | | | Coronal mass ejections (CMEs) are well known to be the main drivers of geomagnetic activity, as well as causing various other space weather phenomena. The most significant CMEs from an Earth perspective are front-sided halo (that fully encompass the solar disc) and partial halo (that cover a wide angle in coronagraph imagery) CMEs.
The source regions of halos and partial halos are usually located close to the central meridian, but a subset of halos originates between $\pm$45° and $\pm$90° in longitude from the central meridian. Such halos are known as limb halos. Limb halos are expected to be less geoeffective than halos originating from closer to the central meridian, because they usually only have glancing encounters with Earth. The study of such CMEs forms an important area of space weather research, due to their unpredictability in causing storms at Earth. Previous studies have suggested that this unpredictability can be mainly attributed to CMEs changing their orientation due to deflections, rotations, and deformations in the low corona.
In this presentation we will explore limb CMEs, and in particular compare the magnetic structure of CMEs at the Sun and in situ for a case study. We present observations of an eruption using EUV (PROBA2/SWAP) and magnetogram (SDO/HMI) observations, analysing the lower coronal signatures of the eruption through the triangulation and line-tying of structures from the STEREO and PROBA2 perspectives. The evolution of the eruption is further characterised out to ∼20 solar radii through forward modelling and coronagraph observations from STEREO/COR and SOHO/LASCO. These are compared to several in situ observations, which are used to reconstruct the CME structure from near its nose to its flank(s), and assess its impact.
| | 16:30 | Launching Hydrodynamic and Magnetic CME-like Structures into the Operational Heliospheric Space Weather Models | Odstrcil, D et al. | Oral | | | Dusan Odstrcil[1,2] | | | [1] George Mason University, [2] NASA/GSFC | | | Operational heliospheric space weather models require simulations of coronal mass ejections (CMEs) much faster than real time for all observed events. Currently, this cannot be routinely achieved by simulations that involve origin of the CMEs. Thus their white-light appearance in coronagraphs is used to fit the geometric and kinematic parameters and launch simple, CME-like structures into the background solar wind. Propagation and interaction in the heliosphere are then solved by a 3-D magnetohydrodynamic (MHD) code. We introduce the “cone” and “spheromak” models for launching hydrodynamic and magnetic structures, respectively, and discuss their peculiarities and various realizations. Selected CME events, characterized by excellent observations from Sun to Earth, are used for numerical simulations of transient disturbances. We use various realizations of the cone and spheromak models and compare the numerical heliospheric results with remote white-light observations and with in-situ measurements of plasma parameters at Earth and STEREO spacecraft. | | 16:45 | Coupled Coronal Mass Ejection - Solar Particle Event Simulations | Linker, J et al. | Oral | | | Jon Linker[1], Ronald Caplan[1], Nathan Schwadron[2], Matthew Gorby[2], Cooper Downs[1], Roberto Lionello[1],Tibor Torok[1], Janvier Wijaya[1] | | | [1]Predictive Science Inc., San Diego, CA, USA [2]University of New Hampshire, Durham, NH | | | Solar Particle Events (SPEs) represent a significant hazard to humans and technological infrastructure in space and aviation. A physics-based description of solar energetic particles (SEPs) is difficult: their generation spans very different plasma regimes and large regions of the heliosphere. We are developing STAT (SPE Threat Assessment Tool), to provide simulations of particle fluxes and dose rates for SPEs. STAT combines CORHEL (Corona-Heliosphere), which produces magnetohydrodynamic (MHD) models of the solar corona and inner heliosphere, including coronal mass ejections (CMEs), with EMMREM (Earth-Moon-Mars Radiation Environment Module), which simulates the acceleration and transport of SEPs using three-dimensional solutions of the focused transport equation. The present version of STAT being delivered to the NASA Community Coordinated Modeling Center (CCMC) allows users to run the Energetic Particle Radiation Environment Module (EPREM) for precomputed MHD models of real CME events. We describe the operation of the tool and its output diagnostics with examples from specific events.
Work supported by NASA and AFOSR.
| | 17:00 | The Effects of Uncertainty on Deflection, Rotation, Bz and Arrival Time Predictions | Kay, C et al. | Oral | | | Christina Kay[1,2], Nat Gopalswamy[1] | | | [1] Solar Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA, [2] Dept. of Physics, The Catholic University of America, Washington DC, USA | | | Understanding the effects of coronal mass ejections (CMEs) requires knowing not only if and when they will impact, but also their properties upon impact. Of particular importance is the strength of a CME's southward magnetic field component (Bz). Kay et al. (2013, 2015) have shown that the simplified analytic model ForeCAT can be used to reproduce the deflection and rotation of CMEs. Kay et al. (2017) introduced FIDO, which uses the position and orientation from ForeCAT to simulate magnetic field profiles. FIDO reproduces the in situ observations on roughly hourly time scales, suggesting that the combination of ForeCAT and FIDO could be extremely useful for predictions of Bz. However, as with all models, both ForeCAT and FIDO are sensitive to their input parameters, which may not be precisely known for actual predictions. We explore the sensitivity of both models using ensembles with small changes in the initial latitude, longitude, and orientation of the erupting CME. Additionally, thus far ForeCAT has only been run using a Potential Field Source Surface (PFSS) magnetic background driven by a synoptic map. We explore the effects of different magnetic backgrounds - the Schatten Current Sheet model and synchronic maps. We find that the changes in deflection and rotation resulting from the uncertainty in the initial parameters tend to exceed the changes from different magnetic backgrounds. The range in the in situ profiles tends to scale with the range in the deflection and rotation. We also consider the effects of these changes in a simple arrival time model and show that accurate arrival times can only be achieved if the CME position and orientation are precisely known.
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Posters| 1 | Forbush Decrease Mechanism in a Magnetic Cloud | Petukhova, A et al. | p-Poster | | | Anastasia Petukhova, Ivan Petukhov, Stanislav Petukhov | | | Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy SB RAS, Yakutsk, Russia | | | Using back tracing we research galactic cosmic ray propagation in a moving magnetic cloud having the shape of magnetic loop. It is obtained that the inductive electric field of an extended magnetic cloud decreases particle energy. Both energy losses and long particle trapping by a magnetic loop produce Forbush decrease. The calculation results of particle density and the components of uni- and bidirectional anisotropies are shown. The calculation results generally agree with measurements. | | 2 | Observing the Sun with LOFAR: Current results and future prospective. | Zucca, P et al. | p-Poster | | | Pietro Zucca[1], Mario Mark Bisi[2], Eoin Carley[3], Bartosz Dabrowski[5], Richard Fallows[1], Peter Gallagher[3], K-Ludwig Klein[4], Andrzej Krankowski[5], Jasmina Magdalenic[6], Christophe Marqué[6], Diana Morosan[7], Hanna Rothkaehl[8], Nicole Vilmer[4], Christian Vocks[9], Gottfried Mann[9] | | | [1]ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo, The Netherlands. [2] RAL Space, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Oxfordshire, UK. [3]Astrophysics Research Group, School of Physics, Trinity College Dublin, Dublin 2, Ireland. [4]LESIA, UMR CNRS 8109, Observatoire de Paris, 92195 Meudon, France. [5] Space Radio-Diagnostics Research Centre, University of Warmia and Mazury in Olsztyn, Poland. [6] Solar-Terrestrial Center of Excellence, Royal Observatory of Belgium, Avenue Circulaire 3, 1180 Brussels, Belgium. [7] Department of Physics, University of Helsinki, Helsinki, Finland [8] Space research Centre of the Polish Academy of Science, 18A Bartycka 00-716 Warsaw, Poland. [9] Leibniz-Institut fur Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany. | | | The Low Frequency ARray (LOFAR) has unique capabilities in the solar physics and space-weather domain, including: 1) the ability to take high resolution solar dynamic spectra and radio images of the Sun; 2) observing the scintillation of distant, compact, astronomical radio sources to determine the density, velocity and turbulence structure of the solar wind; 3) the use of Faraday rotation as a tool to probe the interplanetary magnetic-field strength and direction. The combination of in-situ spacecraft measurements and ground-based remote-sensing observations of coronal and heliospheric plasma parameters is extremely useful for solar physics and space-weather studies. Recently, new observing campaigns able to simultaneously observe the Sun in interferometric and tied-array beam mode while also observing faraday rotation of pulsars and scintillation of compact objects have been successfully performed. In this talk, we introduce this new observing campaign and present some of the recent results and case studies. | | 3 | Investigation of the largest flares of solar cycle 24 and its interplanetary journey | Liliana, D et al. | p-Poster | | | Liliana Dumitru, Cristiana Dumitrache, Diana Ionescu | | | Astronomical Institute of Romanian Academy | | | We investigate the circumstances of the largest solar flare of cycle 24 that were registered by GOES in 6 September 2017. Starting with the HMI magnetograms of NOAA 12673 active region, we extrapolate the coronal magnetic field by applying a NLFFF code.
Numerical MHD simulations are performed, having as input the obtained coronal magnetic field, in order to understand the plasma evolution and the flare/CME onset.
The CME jouney towards the Earth and its effects on the Earth magnetosphere are also analysed.
| | 4 | Homologous prominence non-radial eruptions. | Dechev, M et al. | p-Poster | | | Momchil Dechev[1], Kostadinka Koleva[1], Peter Duchlev[1] | | | [1]Institute of Astronomy and NAO, BAS, Bulgaria | | | We present the results from the study of four homologous prominence eruptions that occurred in active region NOAA 10904 on 2006 August 22. The sequence of prominence eruptions reported here were analyzed by H-alpha data from solar coronagraph on National Astronomical Observatory (NAO-Rozhen) and Mauna Loa Solar Observatory (MLSO). We used also the NoRH 17 GHz radio data for prominence activation analyses. The pre-eruptive phase of the homologous feature as well as the kinematics and the morphology of a series of prominence eruptions are examined. The evolution of the overlying coronal field during homologous eruptions is discussed and a new observational criterion for homologous eruptions is provided. | | 5 | Long-term evolution of the solar corona using SWAP data | Mierla, M et al. | p-Poster | | | Marilena Mierla[1,2],Elke D'Huys[1],Daniel B. Seaton[3],David Berghmans[1],Matt West[1],Elena Podladchikova[1], Laurence Wauters[1], Jan Janssens[4]
| | | [1]Royal Observatory of Belgium,[2]Institute of Geodynamics of the Romanian Academy,[3]NOAA, [4]Solar-Terrestrial Centre of Excellence | | | In this work, we use the PROBA2/SWAP images to study the evolution of the large-scale structures of the solar corona observed in the EUV during the solar cycle 24 (from 2010 to 2018). We will discuss the evolution of the corona at different heights above the solar surface and the evolution of the corona over the poles. We compare it with the sunspot number evolution.
| | 6 | Observing of clusters of high energy particles on neutron monitor | Balabin, Y et al. | p-Poster | | | Yury Balabin | | | Polar Geophysical Institute , Apatity, Russia | | | Neutron monitors Baksan (Northern Caucasus, 42 N), Apatity (67 N) and Barentsburg (arch. Spitsbergen, 78 N) have an advanced data acquisition system. The system registers each neutron monitors (NM) pulse: which tube produced the pulse and time with one microsecond accuracy. The system is used to study multiplicity events on NM. The multiplicity is characterized by the number of M pulses (neutrons). A multiplicity event is clear distinct: at an average interval between pulses is ~22 ms on an NM the intervals between pulses inside an M event are 10-200 mcs and number of events M = 5-200. The multiplicity is two kinds: multiplicity into NM (M = 5-10) and in the atmosphere (M = 10-200). The second kind corresponds to coming in the atmosphere a particle with very high energy from hundreds GeV and more. After upgrading the acquisition system of the monitors are connected to the universal time with accuracy less than 1 mcs. Now three NMs are like one distributed detector. It is found a long sequence of multiplicity events (15-40 events during ~20 seconds) after processing the data. An average time profile and spectrum of multiplicity sequence. Time profile shows a gap before and after the sequence with low number of multiplicity events. Frequency of such sequences is two orders more than occasional fluctuation. Further more, a part of the long sequences of multiplicity are simultaneously on two or three NMs. We consider it to be detected by the neutron monitors quick surges (or clusters) of density in the high-energy particle flux. Larmour radius of 1 TeV particle in the interplanetary magnetic field is compatible to heliosphere size. In this case large scale irregularities of the interplanetary magnetic field could produce such surges. Using a wide net of NMs and solving inversed problem one could derive large scale structure of heliosphere. | | 7 | Exceptional Extended Field of View Observations by SWAP on 1 and 3 April 2017 | O'hara, J et al. | p-Poster | | | Jennifer O'Hara[1], Marilena Mierla[1,2], Elena Podladchikova[1], Elke D'Huys[1], Matthew West[1] | | | [1]Solar–Terrestrial Center of Excellence – SIDC, Royal Observatory of Belgium, Brussels, Belgium, [2]Institute of Geodynamics of the Romanian Academy, Bucharest, Romania | | | On the 1st and 3rd April 2017 two large solar eruptions, which were associated with an M4.4 and M5.8 class flare, respectively, were observed on the solar western limb with the PROBA2/SWAP telescope. The large field of view of SWAP combined with the exceptional circumstances of the satellite being off-pointed in a favorable position to view the events, provide us with the rare opportunity to study these eruptions up to approximately 2 solar radii, where coronagraph observations begin. SWAP observations reveal off-limb erupting features as well as on disk EUV waves initiated by these eruptions. Using this unique set of observations, the evolution of these two events are tracked and the propagating speeds of both the eruptions and the on-disk EUV waves are calculated. | | 8 | Type II radio burst observed by LOFAR on August 25, 2014 | Magdalenic, J et al. | p-Poster | | | Jasmina Magdalenic[1], Christophe Marque[1], Richard Fallows[2], Gottfried Mann[3], Christian Vocks[3] | | | [1] Royal Observatory of Belgium, Solar Physics, Brussels, Belgium, [2] ASTRON, Netherlands Institute for Radio Astronomy, Dwingeloo, Netherlands, [3] Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany | | | The M2.0 class flare on August 25, 2014 originated from the NOAA AR 2146 at that moment situated rather close to the west solar limb. The flare was associated with coronal dimming, EUV wave, halo CME and the type II radio burst observed in the meter to decameter wavelengths. The metric type II burst was observed by the LOFAR (LOw Frequency ARray) radio interferometer. The type II burst shows strong fragmentation of the radio emission, and although fine structures of type II bursts were already reported, the wealth of the fine structures observed in the August 25, 2014 event is unprecedented. Together with the herringbone structures, inverted J-bursts and U-bursts, we observe also narrowband bursts similar to simple narrowband SSSs (Magdalenic et al., 2006), i.e. spike-like, dot-like, sail-like and flag-like bursts, and number of different unclassified bursts. The main characteristics of the fine structures observed within type II burst are compared with the characteristics of type IV fine structures in the same wavelength range, and their possible origin is discussed. | | 9 | An investigation of the early stages of solar eruptions: from remote observations to energetic particles | Kozarev, K et al. | p-Poster | | | Kamen Kozarev[1], Rositsa Miteva[2], Kostadinka Koleva[1], Peter Duchlev[1], Momchil Dechev[1], Astrid Veronig[3], Manuela Temmer[3], Karin Dissauer[3] | | | [1]Institute of Astronomy, Bulgarian Academy of Sciences - Bulgaria, [2]Space Research and Technology Institute, Bulgarian Academy of Sciences - Bulgaria, [3]IGAM-Institute of Physics, University of Graz - Austria | | | Solar energetic particles (SEPs) are one of the most important phenomena of space weather. They are created in flares and shock waves driven by coronal mass ejections (CMEs) under various coronal and interplanetary conditions. The aim of this investigation is to explore in detail the relation between remote and in situ observations, and models of phenomena related to SEP acceleration in CMEs and flares - focusing on the initial phase of the solar eruptions and their efficiency in particle acceleration. We selected a number of events with simultaneous observations in hard X-ray, EUV and radio wavelengths of the SEP-related solar flares, and analyzed the properties of the emission (light curves, spectra and temporal evolution), as well as in situ signatures. The SEP acceleration near the Sun is also modeled. The effect of the various solar eruption phenomena as factors influencing the SEP productivity is evaluated. | | 10 | Investigating CME distortions with the Solar Stormwatch project | Jones, S et al. | p-Poster | | | Shannon Jones[1], Chris Scott[1], Luke Barnard[1], Mathew Owens[1] | | | [1]University of Reading | | | Coronal mass ejections (CMEs) are the main drivers of hazardous space weather. We are using a novel dataset, created with the help of many citizen scientists through the Solar Stormwatch project, to investigate the effect of the solar wind on these storms. Participants track the shape of CME fronts in images from the heliospheric imagers on board the twin STEREO spacecraft, providing an unprecedented level of detail (Barnard et al., 2017). We use this dataset to extend the work of Savani et al. (2010), looking at how CME fronts are distorted under varying solar wind conditions.
Barnard et al. 2017 doi:10.1002/2017SW001609
Savani et al. 2010 doi:10.1088/2041-8205/714/1/L1 | | 11 | Ensemble modeling of CMEs using EUHFORIA | Verbeke, C et al. | p-Poster | | | Christine Verbeke[1], S. Poedts[1], M. Leila Mays[2], Camilla Scolini[1,3], Jens Pomoell[4] | | | [1] Kuleuven, Belgium, [2] NASA GSFC, USA, [3] Royal Observatory Belgium, Belgium, [4] University of Helsinki, Finland | | | Ensemble modeling of Coronal Mass Ejections (CMEs) provides a probabilistic forecast of the CME arrival time. Recently, ensemble modeling has been implemented into the newly-developed MHD heliospheric model EUHFORIA. EUHFORIA is not only able to model CMEs using the cone model, but also by using a flux-rope model which includes a magnetic field structure. This also provides the opportunity to provide the magnetic Bz field which is a key parameter for the geo-effectiveness of CMEs at Earth.
We will present results of ensemble runs for a set of 35 events, for both the cone model and the flux-rope model. The flux-rope model contains extra free magnetic parameters compared the cone model so restrictions on the magnetic field parameters will be based on observations of the observed magnetic field at the time of eruption. We discuss the influence of each parameter on the final results of the ensemble runs and present statistics on the forecasting capabilities of EUHFORIA. | | 12 | Tomography Programing for Space Weather Analysis using the Worldwide IPS Stations Network (WIPSS) | Jackson, B et al. | p-Poster | | | Bernard V. JACKSON[1], Hsiu-Shan YU[1], Paul P. HICK[1], Andrew BUFFINGTON[1],Mario M. BISI[2],Richard A. FALLOWS[3],Munetoshi TOKUMARU[4],Sergei A. TYULl'BASHEV[5], Igor V. CHASEI[5],Victor H. DE LA LUZ[6] | | | [1]Center for Astrophysics and Space Sciences, University of California, San Diego, California, United States, [2]RAL Space, Science & Technology Facilities Council (part of UK Research and Innovation) - Rutherford Appleton Laboratory, Harwell Campus, Oxfordshire, OX11 0QX, United Kingdom, [3]ASTRON – the Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, the Netherlands, [4]Institute for Space-Earth Environmental Research (ISEE), Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601, Japan, [5]Lebedev Physical Institute, Russian Academy of Sciences, Moscow, Russia, [6]SCIESMEX, Instituto de Geofisica, UNAM, Morelia, Mexico | | | The University of California, San Diego (UCSD) time-dependent, iterative, kinematic reconstruction technique has been developed and employed for over two decades. It provides some of the most-accurate predictions and three-dimensional (3-D) reconstructions of heliospheric solar-wind parameters (velocity, density) presently available, using interplanetary scintillation (IPS) data to do this. The modeling input can also incorporate other IPS data sources from around the world, most conveniently using data in a “standard” IPS format. When employing a global network of IPS data systems, not only can IPS predictions be made without observation dead times due to poor longitude coverage or system outages, but the program can also show differences intrinsic to each data set. Here we discuss some of the details and new results using a combination of IPS data from the years 2016 and 2017. Three data sets are currently compared; from ISEE, Japan, from the LOw Frequency ARray (LOFAR), and from g-level data recently made available from the Pushchino, Russia, Big Scanning Array (BSA3). | | 13 | Size Distributions of Solar Proton Events and Their Associated Soft X-ray Flares: Application of the Maximum Likelihood Estimator | D'huys, E et al. | p-Poster | | | D'Huys Elke[1], Cliver Edward W.[2] | | | [1]Royal Observatory of Belgium], [2]National Solar Observatory | | | We use the maximum likelihood estimator (MLE) to determine the slope of the power law size distribution of a subsampled set of the peak fluxes of 106 ~25 MeV solar energetic proton (SEP) events from 1997-2016 associated with western hemisphere soft X-ray (SXR) flares. In addition, we obtained a slope for the peak SXR fluxes of the 112 associated ≥M1 flares, and for the peak SXR fluxes of a sample of 128 flares from 1996-2005 that were associated with coronal mass ejections (CMEs) with speeds ≥1000 km s-1. The slopes of both of these SXR peak flux distributions are closer to that for proton events than to the α value determined for all 177 western hemisphere SXR flares considered from 1996-2005. These results are consistent with those of a previous study, based on a less reliable method (for small samples), in which it was argued that the flatter size distribution generally found for SEP events vs. those for flare electromagnetic emissions was due to the fact that SEP flares are an energetic subset of all flares. | | 14 | Post-Flare Loop Signatures | West, M et al. | p-Poster | | | Matthew West[1], Daniel Seaton[2], Erika Palmerio[3] | | | [1]Royal Observatory of Belgium, [2]NOAA/CIRES , [3]University of Helsinki | | | Recent observations from the SWAP EUV imager onboard PROBA2, AIA on SDO and SXI X-ray observations from the GOES satellite have shown that post-flare giant arches and regular post-flare loops are one and the same thing, with the former being a sub-set of post-flare loops that are able to maintain their growth to great heights over longer periods. However, it is still not clear how certain loop systems are able to sustain this growth to heights that can exceed half a solar radii (> 400000 km). In this presentation we further explore the energy deposition rate in post-flare loop systems, combined with an epoch analysis of the irradiance light curves generated by the initial flare and subsequent decline in emission generated from the post-flare loop systems. | | 15 | Multi-wavelength analysis of proton-producing solar flares | Miteva, R et al. | p-Poster | | | Rositsa Miteva,[1] Astrid Veronig[2], Kostadinka Koleva[3], Momchil Dechev[3], Kamen Kozarev[3], Manuela Temmer[2] | | | [1] Space Research and Technology Institute, Bulgarian Academy of Sciences, [2] Institute of Physics-IGAM, University of Graz, [3] Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences | | | Comparative analysis of solar flare emission in hard X-ray (HXR), soft X-ray (SXR), EUV and radio wavelengths is presented. We selected all solar flares related with SOHO/ERNE 20 MeV protons during the period of RHESSI observations (since 2002). About 70 flare events with good data coverage are finally considered. The objective of the study is to correlate the flare amplitude in various wavelengths, as an alternative to the SXRs, with the peak proton intensity. The results show that the relationship between protons and non-thermal flare emission tends to be weaker compared to the speed of coronal mass ejections. We discuss under which conditions the flare origin of the in situ protons becomes prominent (e.g. open magnetic field configuration, etc.) and propose new flare parameters for proton forecasting. | | 16 | Ensemble forecast of the background solar wind and CMEs | Luo, B et al. | p-Poster | | | B. Luo[1], J. Wang[1], Y. Zhu[2], S. Yang[2], S. Liu[1], J. Gong[1] | | | [1]National Space Science Center, Chinese Academy of Sciences, [2]China Xi’an Satellite Control Center | | | We present the ensemble forecasts of the background solar wind and CMEs, mainly based on the operational solar wind prediction system of Space Environment Prediction Center in China. This system is mainly composed of three modules: 1) a photospheric magnetic field extrapolation module (PFSS), along with a Wang-Sheeley-Arge (WSA) empirical method, to obtain the background solar wind speed and the magnetic field strength on the source field; 2) a modified Hakamada-Akasofu-Fry (HAF) kinematic module for simulating the propagation of solar wind structures in the interplanetary space; and 3) a module for CME detection and parameter derivation using the ice-cream cone model based on coronagraph images. The real-time solar magnetic field synoptic charts obtained from NSO/GONG are fed into the PFSS model first and are used to drive the HAF model. Several functions published in literatures relating the expansion of magnetic field to solar wind speed empirically are coupled to the HAF model. An ensemble of CME parameters is derived by multiple fronts obtained from a series of coronagraph images and fed into the system for propagation simulation based on the different background solar wind conditions. Finally, the simulated background solar wind and CMEs at 1AU are compared with ACE observations. Ensemble forecast method can enable a sensitivity analysis for forecast accuracy, and thus improve the accuracy significantly. | | 17 | Radio Signatures of Shock Accelerated Electron Beams in the Corona | Mann, G et al. | p-Poster | | | Gottfried Mann[1], Valentin N. Melnik[2], Helmut O. Rucker[3], Alexander A. Konovalenko[2], Aanatoli I. Brazhenko[4] | | | [1]Leibniz-Institut fuer Astrophysik Potsdam, [2]National Academy of Sciences of Ukraine, Institute of Radio Astronomy, [3]Commission for Astronomy, Austrian Academy of Sciences, [4]Poltava Gravimetrical Observatory of Institute of Geophysics of NASU | | | The Sun’s activity can appear in terms of radio bursts. Solar type II radio bursts are signatures of shock waves traveling through the corona. The Ukrainian radio telescope URAN-2 observed special fine structures in type II radio bursts in the frequency range 8-33 MHz. They appear as a chain of stripes of enhanced radio emission in dynamic radio spectra. The chain drifts slowly from 26 to 23 MHz within 240 s. The individual structures consists of a “head” and a “tail”, which rapidly drifts towards lower frequencies. They resemble the well-known “herringbones” in type II radio bursts and are regarded as radio signatures of shock accelerated electron beams. Adopting shock drift acceleration (SDA) for generating energetic electrons, these electrons establish a beam-like velocity distribution. Such a distribution is able to excite Langmuir waves, which convert into radio waves by nonlinear plasma processes (also called plasma emission). This process is efficient if the velocity of the beam electrons exceeds a few times of the thermal electron speed. The data of the dynamic radio spectrum recorded by URAN-2 can be related in the best way to the theoretical results, if the electron beams responsible for the ‘herringbones’ are generated via SDA at an almost perpendicular shock which is traveling nearly horizontal to the surface of the Sun. | | 18 | Impulsive CME expansion and fast EUV wave associated with the September 10, 2017 X8.2 flare observed by GOES/SUVI | Veronig, A et al. | p-Poster | | | Astrid M. Veronig[1], Tatiana Podladchikova[2], Karin Dissauer[1], Manuela Temmer[1], Daniel B. Seaton[3,4], Jingnan Guo[5] | | | [1]Institute of Physics & Kanzelhöhe Observatory, University of Graz, Austria, [2]Skolkovo Institute of Science and Technology, Moscow, Russia, [3]Cooperative Institute for Research in Environmental Science, University of Colorado at Boulder, CO, USA, [4]National Centers for Environmental Information, National Oceanic and Atmospheric Administration, Boulder, CO, USA, [5]Institut für Experimentelle und Angewandte Physik, University of Kiel, Germany | | | On September 10th, 2017 a large solar eruption, accompanied by an X8.2 solar flare from NOAA Active Region 12673 was observed on the Sun’s western limb by the new Solar Ultraviolet Imager (SUVI) on the GOES-16 spacecraft (Seaton and Darnel 2018). This was the second largest flare in solar cycle 24, accompanied by a very fast coronal mass ejection (CME) with a speed up to 3500 km/s. The associated SEP event was the first Ground Level Enhancement (GLE) that was observed on the surface of two different planets, Earth and Mars (Guo et al. 2018). The EUV wave associated with this event was also special in several aspects: in terms of its high speed (>1000 km/s) indicative of its shock nature, the large height above the solar limb to which it was observed, the various interaction processes with plasma structures in the corona and its global propagation over the solar surface as seen by SUVI and STEREO-A.
We study in detail the early expansion and acceleration phase of the CME and the associated EUV wave formation. We present a method to identify the CME bubble shape in order to characterize its radial and lateral motion. The large field of view of SUVI allows us to study the early impulsive CME acceleration up to about 1.9 solar radii. The CME reveals a very fast evolution with strong lateral overexpansion. The radial acceleration of the CME reaches a peak value of about 5 km/s2, whereas the lateral expansion reveals an even higher peak value of about 9 km/s2. The EUV wave/shock formation can be clearly observed above the solar limb, and occurs close in time to the peak of the strong lateral overexpansion of the CME. Thereafter, the wave detaches from the expanding CME flanks and propagates freely. The EUV wave reveals a global propagation over the full SUVI field-of-view as well as into the STEREO-A field-of-view (at a separation of 128°), and can be followed up to distances of at least 1700 Mm from the source region. We study the propagation and kinematics of the direct as well as the various reflected and refracted EUV wave components on the solar sphere, finding speeds in the range from 370 to >1000 km/s. Finally, we note that this EUV wave is also distinct as it reveals propagation and transmission through the polar coronal holes. | | 19 | LOFAR observations of fine spectral structure dynamics in type IIIb radio bursts | Sharykin, I et al. | p-Poster | | | Ivan Sharykin[1,2,3], Eduard Kontar[2], Alexey Kuznetsov[3] | | | [1]Space Research Institute, Moscow, Russia; [2]Glasgow University, School of Astronomy and Astrophysics, Glasgow, UK; [3]Institute of Solar-Terrestrial Physics, Irkutsk, Russia | | | Solar radio emission features a large number of fine structures demonstrating great variability in frequency and time. We present spatially resolved spectral radio observations of type IIIb bursts in the $30-80$ MHz range made by the Low Frequency Array (LOFAR). The bursts show well-defined fine frequency structuring called ``stria'' bursts. The spatial characteristics of the stria sources are determined by the propagation effects of radio waves; their movement and expansion speeds are in the range of $(0.1-0.6)c$. Analysis of the dynamic spectra reveals that both the spectral bandwidth and the frequency drift rate of the striae increase with an increase of their central frequency; the striae bandwidths are in the range of $\sim (20-100)$ kHz and the striae drift rates vary from zero to $\sim 0.3$ MHz $\textrm{s}^{-1}$. The observed spectral characteristics of the stria bursts are consistent with the model involving modulation of the type III burst emission mechanism by small-amplitude fluctuations of the plasma density along the electron beam path. We estimate that the relative amplitude of the density fluctuations is of $\Delta n/n\sim 10^{-3}$, their characteristic length scale is less than 1000 km, and the characteristic propagation speed is in the range of $400-800$ km $\textrm{s}^{-1}$. These parameters indicate that the observed fine spectral structures could be produced by propagating magnetohydrodynamic waves. | | 20 | Flow patterns observed in ascending phase of the flare on March 6, 2012 | Philishvili, E et al. | p-Poster | | | E.Philishvili [1,3], B.M.Shergelashvili [2,3,5], J.Raes [1], S.Poedts[1] ,T.V. Zaqarashvili [2,3,4], M.L.Khodachenko [2] and P.De Causmaecker [5] | | | [1] CmPA, KU Leuven, [2] Space Research Institute, Austrian Academy of Sciences [3] Abastumani Astrophysical Observatory, Ilia State University [4] Institute of Physics, IGAM, University of Graz [5] Combinatorial Optomization and Decision Support, KU Leuven | | | The complex solar magnetic fields in the corona hosts many different eruptive and explosive like events, which are manifested in different type of flow patterns in the magnetic loop systems. We studied number of such flow patterns in the magnetic loops using the observations of SDO/AIA and SDO/HMI for AR 11429 in ascending phase of the flare. A M2.1 class flare (Fig.1) occurs at 12:23 UT, peaks at 12:41 UT and undergoes decay phase until 23:56 UT. From flare onset until 12:36 UT the variety of phenomena took place, including the reconnection, rapid plasma ejection, quasi-periodic oscillations and flows. We investigated the spatial and temporal behavior of the magnetic loop structures with examining space-time diagrams and DEM analysis. We have obtained characteristic temperatures and velocities of the flows. We detected set of transient flows with the velocity range in 15-215 km/sec. According to our findings, we interpret these events as the results of thermally and hydrodynamically unstable sources. | | 21 | Linking the solar dynamo field and the wind: the impact of self-consistent dynamical coupling | Perri, B et al. | p-Poster | | | Barbara Perri[1], Victor Réville[2], Allan Sacha Brun[1], Antoine Strugarek[1] | | | [1]Laboratoire AIM Paris-Saclay, Université Paris-Diderot, DSM/IRFU/DAp, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France, [2]EPSS, University of California, Los Angeles, CA, United States | | | Observations have shown that the 11-year cycle created by the dynamo inside the Sun has a strong impact on the latitudinal speed distribution of the solar wind, and that the wind has an important role in the shaping the magnetic field in the corona. Quasi-static numerical studies have focused on the impact of the magnetic field on the wind, but due to the large diversity of scales and physical processes involved, a proper dynamical coupling has never been tried for the whole Sun, hence never studying the back-reaction of the wind on the dynamics of the star.
We use the PLUTO code to compute simultaneously both the evolution of the magnetic field inside the star (dynamo process) and the dynamical response of the wind in the corona in 2.5D. The dynamo inside the star is driven by an alpha-omega mechanism, which is fine-tuned to obtain a solar-like 11-year cycle. Through a multi-layered internal boundary condition, the magnetic field variations resulting from dynamo action are transmitted to a realistic solar wind which can adapt and back-react. This model aims at filling the gap between 0.7 and 20 solar radii for a precise wind prescription, which could then be used as enhanced boundary condition for models predicting geo-effective events. | | 22 | Insights into Coronal Mass Ejection Shock Kinematics with the Irish Low Frequency Array (I-LOFAR) | Maguire, C et al. | p-Poster | | | Maguire C, Gallagher P, Carley E, Nally A, Zucca P | | | 1 Trinity College Dublin, Dublin, Ireland . 2 ASTRON Netherlands Institute for Radio Astronomy, Dwingeloo, The Netherlands | | | The Sun can produce large-scale energetic events such as solar flares and coronal mass ejections (CMEs) which can excite shock waves that propagate through the corona. To date, the shock kinematics responsible for particle acceleration and emission at radio wavelengths are not well known. Here, we investigate these phenomena using radio observations of the September 2, 2017 C7.7 solar flare at 10-240 MHz from the recently constructed Irish Low Frequency Array (I-LOFAR; www.lofar.ie). The flare was produced from NOAA Active Region 12672, located on the western limb. SOHO/LASCO recorded a CME that reached maximum speeds of 1041 km/s (average speed of 449 km/s) . Here, we present an analysis of the I-LOFAR observations of a Type II radio burst associated with the shock driven by the CME. In particular, we will describe how features in dynamics spectra obtained using I-LOFAR, such as drift rates and band-splitting, are related to the shock kinematics as derived from imaging observations using the Atmospheric Imaging Assembly (AIA). A combination of I-LOFAR and AIA observations are used to estimate shock velocities, compression ratios and Mach numbers, allowing us to better understand the relationship between the shock kinematics and its radio signature. | | 23 | Numerical simulations of ICMES up to 1AU | Hosteaux, S et al. | p-Poster | | | Skralan Hosteaux[1], Emmanuel Chané[1], Stefaan Poedts[1] | | | [1]KU Leuven | | | The characteristics of a magnetic cloud of an ICME and its associated shock play a key role in the geoffectiveness of the ICME and are thus important factors in space weather studies. In this research, numerical MHD simulations were performed in 2.5D to investigate the propagational properties of ICMEs up to 1AU by superposing a high density/pressure sphere on a relaxed background solar wind. An adaptive mesh refinement scheme is used to achieve high accuracy in regions of interest, e.g. the shock front and the internal magnetic cloud. The effects that initial parameters, such as the initial polarity/velocity of the ICME and the density of the background wind, have on the evolution are investigated and quantified. The simulations are also compared to observational data at L1. | | 24 | Estimating Uncertainty Polar Coronal Hole Measurements Using Multiple Observations Over Two Solar Cycles | Kirk, M et al. | p-Poster | | | Michael S.F. Kirk[1], W. Dean Pesnell[2], C. Nickolos Arge[2] | | | [1] NASA Goddard Space Flight Center and Catholic University of America, [2] NASA Goddard Space Flight Center | | | Polar coronal holes are prevalent during solar minimum, non-axisymmetric, and are stable. These coronal holes are the origin of the bulk of the fast solar wind and define the quiescent heliosphere. Polar holes also offer an indirect measurement of the polar magnetic flux. They are regularly observed capping the northern and southern solar poles in EUV images of the corona and are the longest lived features on the Sun. We make new measurements of polar hole’s perimeter and area in three EUV wavelengths between 1996 and 2017 using five different space-based imagers: SOHO EIT, STEREO A and B EUVI, PROBA2 SWAP, and SDO AIA. The generated time-series of coronal hole parameters have significant oscillatory power in them – however this produces a difficult data problem: multi-band, multi-instrument, heteroscedastic measurements with periodic signals. To separate the oscillations associated with physical phenomena from systematic measurement errors, we employ a generalized Lomb-Scargle periodic analysis. This technique allows us to simultaneously analyze the physical properties of polar coronal holes and identify regular periodicities in our data from other origins. By characterizing the uncertainty of the hole boundary, we derive accurate measurements of polar coronal hole size, location, and evolution. | | 25 | Reconnecting current sheets in a CME-CME interaction region | Yordanova, E et al. | p-Poster | | | E. Yordanova[1], Z. Vörös[2], E. Kilpua[3], C. Möstl[2], M. Temmer[4], A. P. Dimmock[1], L. Rosenqvist[5], M. André[1] and E. Carlsson Sjöberg[6] | | | [1] Swedish Institute of Space Physics, Uppsala, Sweden, [2] Space Research Institute, Austrian Academy of Sciences, Graz, Austria, [3] University of Helsinki, Helsinki, Finland, [4] Institute of Physics, University of Graz, Graz, Austria, [5] Swedish Defense Research Agency, Sweden, [6] Swedish Institute of Space Physics, Kiruna, Sweden | | | The purpose of this study is to investigate local interactions and reconnection processes occurring inside CMEs at L1 and their impact on geoeffectivity. It has been suggested that current sheets present in the compressed leading edges of CMEs and at the trailing edges of magnetic clouds are possible reconnection sites, where the magnetic field changes direction and magnetic flux could be eroded. Such processes at L1 could alter the geoeffectivity of CMEs if forecasts are made without taking into account the effects from reconnection. We study multiple small-scale (minutes long) current sheets detected by WIND, ACE and DSCOVR in a CME-CME interaction region during the 6-8 Sep 2017 event. We observe signatures of reconnection in some of the current sheets, such as changes in magnetic field topology, plasma outflows, and plasma heating. The three solar wind monitors are well positioned along the GSE X direction, allowing us to study the time evolution of such small-scale structures. We present evidence of magnetic field reorganization in the same structure identified by three spacecraft. This result suggests that magnetic reconnection is a mechanism which can potentially affect the geoeffectivity of CMEs. | | 26 | Multiple Regions of Shock Accelerated Particles in the Solar Corona | Gallagher, P et al. | p-Poster | | | Peter T. Gallagher[1], Diana E. Morosan[1,2], Laura A. Hayes[1,3], Sophie A. Murray[1], Eoin P. Carley[1], Pietro Zucca[4], Richard A. Fallows[4], Joe McCauley[1], Emilia Kilpua[2], Gottfried Mann[5], Christian Vocks[5] | | | [1] School of Physics, Trinity College Dublin, Dublin 2, Ireland, [2] Department of Physics, University of Helsinki, P.O. Box 64, Helsinki, Finland, [3] Solar Physics Laboratory, Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA, [4] ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands, [5] Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany | | | The Sun is an active star that produces the most powerful explosions in the solar system. These explosions are often accompanied by coronal mass ejections (CMEs), which can drive colisionless shocks that accelerate particles to high energies. The resulting low frequency radio emission (<200 MHz) can be used to understand the nature of these shocks and associated particle acceleration, which are universal processes in astrophysical plas- mas. However, the relationship between shocks, particle acceleration and CME expansion is still not well understood, partially due to the imaging limitations at low frequencies, where the most dramatic particle accelera- tion signatures are observed. Here, we report unique imaging of an X8.2-class solar flare and associated fast CME (3000$\pm$300~km/s) from the Low Frequency Array, NASA’s Solar Dynamics Observatory, ESA/NASA’s Solar and Heliospheric Observatory and NOAA’s Geostationary Operational Environmental Satellites. We identify the location of a multitude of radio shock signatures, called herringbones, and find evidence for shock accelerated individual electron beams at multiple locations along an expanding CME flank. | | 27 | Observations the different types of radio bursts with LOFAR station in Baldy | Dabrowski, B et al. | p-Poster | | | Bartosz P. Dabrowski[1], Diana E. Morosan[2], Richard Fallows[3], Leszek Blaszkiewicz[1,4], Andrzej Krankowski[1], Jasmina Magdalenic[5], Christian Vocks[6], Gottfried Mann[6], Pietro Zucca[3], Tomasz Sidorowicz[1], Marcin Hajduk[1], Kacper Kotulak[1], Adam Fron[1], Karolina Sniadkowska[1] | | | [1]Space Radio-Diagnostics Research Center, University of Warmia and Mazury in Olsztyn, Poland, [2]Department of Physics, University of Helsinki, Helsinki, Finland, [3]ASTRON - The Netherlands Institute for Radio Astronomy, Dwingeloo, Netherlands, [4]Faculty of Mathematics and Computer Sciences, University of Warmia and Mazury in Olsztyn, Poland, [5]Royal Observatory of Belgium, Brussels, Belgium, [6]Leibniz-Institut fur Astrophysik Potsdam, Potsdam, Germany, | | | We report results of solar spectroscopic observations carried out with the Baldy LOFAR station, Poland from October 2016 to May 2018. During this time, we observed different types of radio bursts, like for example type I and III radio bursts. The observations are taken mainly from Friday to Sunday because the remaining time is reserved for operation within International LOFAR Telescope mode. Our observations show that the station is fully operational and is capable to work efficiently in the single station mode for solar observations at low frequencies. These observations can be used in conjunction with other wavelengths to determine various events occurring on the Sun. The LOFAR single station has unique capabilities which include the high frequency resolution of 0.39 MHz, high sensitivity, and the high frequency bandwidth.
| | 28 | On the possibility of the use of recurrent Forbush decreases in the Space Weather tasks | Papaioannou, A et al. | p-Poster | | | A. Melkumyan[1], A.V. Belov[2], E.A. Eroshenko[2], A.A. Abunin[2], M. A. Abunina[2], V.A.Oleneva[2], V.G. Yanke[2], A. Papaioannou[3] | | | [1] Gubkin Russian State University of Oil and Gas (National Research University) Moscow, Russia, [2] Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation RAS (IZMIRAN),Troitsk, Moscow, Russia, [3] Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing (IAASARS), National Observatory of Athens, Greece | | | We represent the statistical analysis of Forbush decreases (FDs), solar wind and geomagnetic activity parameters for FDs associated with recurrent high speed streams from coronal holes (CHs). The Forbush Effects and Interplanetary Disturbances (FEID) database created in IZMIRAN has been used. We selected 3475 independent FDs (FULL group) out of the FEID database from 1964 and we were able to select within of this group 350 FDs associated with recurrent high speed streams (CH group) and 207 FDs caused by interplanetary coronal mass ejections (CME group). Each event was characterized by six parameters – maximum values of solar wind velocity, interplanetary magnetic field intensity and geomagnetic index Apmax as well as maximum variations of cosmic rays density, anisotropy and density decrease rate .Statistical analysis for listed above parameters and groups included distribution analysis, calculating descriptive statistics and correlation coefficients; computing simple and multiple linear regression models. The results show that in despite of large differences in high speed streams from coronal holes, CH group turned out to be more compact and homogeneous in comparison withthe events associated with CMEs. FDs associated with CHs find out to be less dependent on the characteristics of interplanetary disturbances than FDs associated with CMEs. This indicates a significant difference in mechanisms producing these FDs. | | 29 | A catalogue of Forbush decreases recorded on the surface of Mars from 2012 until 2016: comparison with terrestrial FDs | Papaioannou, A et al. | p-Poster | | | A. Papaioannou[1], A. Belov[2], M. Abunina[2], J. Guo[3], A. Anastasiadis[1], R. Wimmer-Schweingruber[3], E. Eroshenko[2], A. Melkumyan[3], A. Abunin[2], B. Heber[4], K. Herbst[4], C.T. Steigies[4] | | | [1] Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing (IAASARS), National Observatory of Athens, Greece, [2] Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation by N.V. Pushkov RAS (IZMIRAN), Moscow Troitsk, Russia, [3] Gubkin Russian State University of Oil and Gas (National Research University), Moscow, 119991 Russia, [4] Christian-Albrechts-Universität zu Kiel, Germany | | | Forbush decreases (FDs) in galactic cosmic rays (GCRs) have been recorded by neutron monitors (NMs) at Earth for more than 60 years. For the past five years, with the establishment of the Radiation Assessment Detector (RAD) on board the Mars Science Laboratory (MSL) rover Curiosity at Mars, it is possible to continuously detect, for the first time, FDs at another planet: Mars. In this work, we have compiled a catalogue of 424 FDs at Mars using RAD dose rate data, from 2012 to 2016. Furthermore, we applied a comparative statistical analysis of the FDs measured at Mars, by RAD, and at Earth, by NMs, for the same time span. One should note, though, that the Martian atmosphere shields away most of the GCRs protons which have energies < 150 MeV. This cutoff is lower than the atmospheric cutoff at Earth (~ 450 MeV) and the definite energy of 9.1 GeV that corresponds to the rigidity of 10 GV, used for the FDs at Earth in this study. A carefully chosen sample of FDs at Earth and at Mars, driven by the same ICME, led to a significant correlation (cc=0.71) and a linear regression between the sizes of the FDs at the different observing points, for the respective energies. We, further, show that the amplitude of the FD at Mars (for E>150 MeV) is higher by a factor of 1.5-2 compared to the size of the FD at Earth for (E=9.1 GeV). Finally, almost identical regressions were obtained for both Earth and Mars as concerns the dependence of the maximum hourly decrease of the CR density to the size of the FD. | | 30 | Interplanetary Coronal Mass Ejections as the driver of non-recurrent Forbush Decreases | Papaioannou, A et al. | p-Poster | | | A. Belov[1], A. Papaioannou[2], M. Abunina[1], E. Eroshenko[1], A. Anastasiadis[2], S. Patsourakos[3], H. Mavromichalaki[4], A. Abunin[1] | | | [1] Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation by N.V. Pushkov RAS (IZMIRAN), Moscow Troitsk, Russia, [2] Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing (IAASARS), National Observatory of Athens, Greece, [3] Section of Astrogeophysics, Department of Physics, University of Ioannina, Greece, [4] Nuclear and Particle Physics Section, Physics Department, National and Kapodistrian University of Athens, Greece | | | Interplanetary coronal mass ejections (ICMEs) are solar wind structures, which usually are referred to as the counterparts of coronal mass ejections. ICMEs and their corresponding shocks can sweep out galactic cosmic rays (GCRs) and thus modulate their intensity, resulting to non-recurrent Forbush decreases (FDs). Depending on the observer's relative position to the propagating disturbance (i.e. ICME), it is possible to encounter both the shock and the ejecta of an ICME or only its shock. There are also cases where the ICME is weak and thus unable of driving a shock. In addition, some ICME may include a magnetic cloud (MC). As a result there are, in principle, three different groups of non-recurrent FD events that can be distinguished: (i) those that are associated to both shocks and ejecta; (ii) those that are associated only to shocks and (iii) those that are associated only to an ejecta. Out of these three groups, naturally, group (i) also includes FD events for which the driving ICME was a MC. Each group is directed by the different manifestations of its driving source and thus it can be used for the identification of the different physical mechanisms at work. In this work, we selected FDs that were associated to sudden strom commencements (SSCs) and a CME was identified as a source. As a result, we excluded all FDs that were driven only by weak ejectas (i.e. no shock was marked; group (iii), here above). At the same time, we employed the t_{H} parameter, which is the time delay (in hours) from the maximum of the magnetic field strength of the interplanetary Magnetic Field (IMF) in the FD to the onset of the FD event (as this is marked via the SSC). For the resulting grouping of events we examine: the mean characteristics of the FDs and the associated interplanetary (IP) variations per group, as well as the resulting correlations. In addition, we demonstrate the outputs of a superposed epoch analysis, which was used in order to obtain an average time profile of the resulting FDs and the corresponding interplanetary variations, per sample. | | 31 | Continuum emission enhancements and penumbral changes observed during flares by Hinode, IRIS and ROSA | Zuccarello, F et al. | p-Poster | | | Francesca Zuccarello[1], Vincenzo Capparelli[1], Mihalis Mathioudakis[2], Peter Keys[2], Lyndsay Fletcher[3], Serena Criscuoli[4], Mariachiara Falco[5], Salvo L. Guglielmino[1], Mariarita Murabito[6] | | | [1]Dipartimento di Fisica e Astronomia - Sezione Astrofisica, Universita` di Catania, via S. Sofia 78, 95123 Catania, Italy, [2] Astrophysics Research Centre, School of Mathematics & Physics, Queen’s University Belfast, Belfast, BT7 1NN, UK, [3] SUPA, School of Physics & Astronomy, University of Glasgow, G12 8QQ, Scotland, UK, [4] NSO - National Solar Observatory, Sacramento Peak - Box 62, Sunspot NM 88349, USA, [5] INAF - Osservatorio Astrofisico di Catania, Via S. Sofia 78, 95123 Catania, Italy, [6] INAF - Osservatorio Astronomico di Roma, Via Frascati 33, Monte Porzio Catone (RM), I-00040, Italy | | | During solar flares, magnetic energy can be converted into electromagnetic radiation from radio waves to γ rays. In the most energetic events, enhancements in the continuum at visible wavelengths may be present (white-light [WL] flares). Recently, the WL emission has also been correlated with enhancements in the FUV and NUV passbands. Moreover, the strong energy release occurring in these events is able to lead to a rearrangement of the magnetic field also at the photospheric level, causing morphological changes also in large and stable magnetic structures like sunspots.
In this context, we describe observations acquired by satellite instruments (Hinode/SOT and IRIS) and ground-based telescopes (ROSA@DST) during two consecutive C7.0 and X1.6 flares occurred in active region NOAA 12205 on 2014 November 7.
The results of the analysis of these data show the presence of continuum enhancements during the evolution of the events, observed both in ROSA images and in IRIS spectra. Moreover, we analyze the role played by the evolution of the δ sunspots of the active region in the flare triggering, discussing the disappearance of a large portion of penumbra around these sunspots as a further consequence of these energetic flares.
| | 32 | Numerical Modelling of Stealth Solar Eruptions Inserted in Different Solar Wind Speeds and Comparison with In-Situ Signatures at 1AU | Talpeanu, D et al. | p-Poster | | | Dana-Camelia Talpeanu[1,2], Francesco P. Zuccarello[1], Emmanuel Chané[1], Stefaan Poedts[1], Elke D'Huys[2], Skralan Hosteaux[1], Marilena Mierla[2,3] | | | [1] CmPA, KU Leuven, 3001 Heverlee, Belgium, [2] SIDC, Royal Observatory of Belgium, Brussels, Belgium, [3] Institute of Geodynamics of the Romanian Academy, Bucharest, Romania | | | Coronal Mass Ejections (CMEs) are huge expulsions of magnetized plasma from the Sun into the interplanetary medium. A subset of CMEs are the so-called stealth CMEs, i.e., solar eruptions that are clearly distinguished in coronagraph observations, but are not associated with clear signatures close to the Sun, such as solar flares, coronal dimmings, EUV waves, or post-flare loop arcades. Observational studies show that about 60% of stealth CMEs are preceded by another CME whose solar origin could be identified.
In order to determine the triggering mechanism for stealth CMEs we are using the MPI-AMRVAC code developed at KU Leuven. We simulate consecutive CMEs ejected from the southernmost part of an initial configuration constituted by three magnetic arcades embedded in a globally bipolar magnetic field. The stealth CME is preceded by a first eruption which is driven through shearing motions at the solar surface. Both are expelled into a bimodal solar wind, varying its speed to match the CMEs arrival time at Earth. We analyze the parameters that contribute to the occurrence of the second CME. Furthermore, we compare the simulated signatures of the two consecutive CMEs with the in-situ data from ACE spacecraft at 1AU. This study aims to better understand the triggering mechanism of stealth eruptions and improve the forecasting of their geomagnetic impact. | | 33 | Modelling Solar Energetic Particle Events Using EUHFORIA | Wijsen, N et al. | p-Poster | | | Nicolas Wijsen[1], Angels Aran[2], Jens Pomoell[3], Stefaan Poedts[1] | | | [1]KU Leuven, [2]University of Barcelona, [3] University of Helsinki | | | After leaving their acceleration site, solar energetic particles (SEPs) propagate in interplanetary space with trajectories determined by the Lorentz force. This force results from a combination of the large scale magnetic field originating from the sun, and small-scale magnetic turbulence due to plasma waves and meandering field lines. The global structure of the interplanetary magnetic field essentially reflects the large scale magnetic structure in the corona. During solar maximum, the coronal magnetic field can be very complex, yielding a solar wind strongly deviating from a nominal Parker configuration. Coronal holes near the solar equator can generate a solar wind with varying plasma flows, and a complex current sheet topology will result in alternating magnetic field polarities. In addition, eruptive transient events occurring in the solar corona, like coronal mass ejections, will strongly perturb the solar wind during their propagation in the heliosphere. In this work, we study how SEP events are influenced by a solar wind containing significant magnetic structures. This is done by using a Monte Carlo particle transport code that propagates particles in a background solar wind generated by the data-driven heliospheric model, EUHFORIA. EUHFORIA solves the magnetohydrodynamic (MHD) equations, allowing us to obtain different solar wind configurations with non-nominal magnetic topologies and velocity profiles. In this work we in particular focus on how such solar wind configurations influence the variation of peak intensities along the radial, longitudinal and latitudinal direction. | | 34 | Precursory signs of Forbush decreases during solar cycle 24 | Lingri, D et al. | p-Poster | | | Dimitra Lingri[1], Helen Mavromichalaki[1], Anatoly Belov[2], Maria Abunina[2], Eugenia Eroshenko[2] | | | [1] Faculty of Physics, National and Kapodistrian University of Athens, Athens, Greece, [2] Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) of the Russian Academy of Sciences, Moscow, Russia | | | The current solar cycle 24 is now ending and in the whole time period of it a serious number of Forbush effects of the cosmic ray intensity, with amplitude of the decrease greater than 2%, have been taken place. The majority of these decreases have followed by sudden storm commencements (SSCs) that happened on the upper magnetosphere in the most cases due to a halo CME coming from the Sun. It is studied if they appeared precursory signs before the main event, by using the ‘ring of stations’ diagrams. Cosmic ray data from the NMDB and IZMIRAN database have been used, as well as solar, interplanetary and geomagnetic characteristic parameters of each event have been analyzed. The pre-decreases and pre-increases of the Forbush decreases of the cosmic ray intensity are examined and, in compile to the other parameters, their common features are discussed. | | 35 | Fully kinetic simulations of electron and ion temperature-anisotropy instabilities in the solar wind using the ECSIM code | Micera, A et al. | p-Poster | | | A. Micera[1,2], A. N. Zhukov[1,3], E. Boella[2], D. Gonzalez-Herrero[2] and G. Lapenta[2] | | | [1] Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, 1180 Brussels, Belgium, [2] Department of Mathematics, KU Leuven, 3001 Heverlee, Belgium, [3] Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow, Russia | | | Kinetic modelling of solar wind is computationally expensive and hard to perform due to the simultaneous presence of strictly interconnected micro and macroscopic scales. As a consequence, kinetic simulations of solar wind processes are very hard to perform within the existing numerical techniques.
Recently, an innovative semi-implicit Particle-in-Cell (PIC) code has been developed. The algorithm, called ECSIM allows for relaxing the rigid stability and accuracy typical of previous PIC schemes, yielding to model space plasma phenomena over a wide range of temporal and spatial resolution.
In this work, by resorting to ECsim, we investigate the microscopic plasma dynamics of temperature anisotropy driven instabilities in the solar wind retaining a kinetic description for both electrons and ions.
Multi-dimensional PIC simulations have been carried out to study the long-term evolution of the firehose and mirror instabilities using physical parameters peculiar of the solar wind at 1 and 0.25 A.U. and realistic electron-proton mass ratios. The interplay between electron and proton anisotropies is explored for the first time.
We examine the effects of the wave activities in scattering particles and in reducing the anisotropies to marginally stable states and we analyse the fields at saturation. Our results will be of fundamental importance in interpreting the data collected by Parker Solar Probe in the near-future | | 36 | Understanding the effect of the 2017 September 10 flare on VLF waves | Cid, C et al. | p-Poster | | | Consuelo Cid[1], Elena Saiz[1], Antonio Guerrero[1], Alberto Garcia[1], Fernando Montoya[1], Jasmina Magdalenic[2], Yolanda Cerrato[1] | | | [1] Space Weather Group, University of Alcalá, [2] Royal Observatory of Belgium | | | The anomaly on the VLF signal due to the flare on 2017 September 10 was recorded with the UAH-VLF receptor starting before the GOES X-flare. As the effect on the ionosphere cannot be ahead of the solar source disturbing it, other emission from the Sun should have occurred before the soft X-rays emission. This non-typical behavior is analyzed by comparison of the data recorded by the UAH-VLF receptor, the X-ray flux from GOES and the Sun brightness temperature from SMOS data, among other data sets, during the X-flares on September 6 and 10. | | 37 | Practical realization of the Force-free Magnetic Field models | Petukhova, A et al. | p-Poster | | | Anastasia Petukhova, Ivan Petukhov, Stanislav Petukhov | | | Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy SB RAS, Yakutsk, Russia | | | To apply force-free magnetic field models we present and discuss properties and feathers of the following models: Miller and Turner solution, modified Miller and Turner solution, Romashets and Vandas solution, Integral model, Krittinatham and Ruffolo model. These models can be used to interpret in-situ observations of the magnetic flux rope, study Forbush decrease in magnetic clouds or investigate transport effects of solar energetic particles injected inside a coronal mass ejection. | | 38 | SPARTOS: a forecasting tool for fast CME arrivals | Corona-romero, P et al. | p-Poster | | | P. Corona-Romero, J.A. Gonzalez-Esparza, E. Aguilar-Rodriguez, J.C. Mejia-Ambriz, M. Sergeeva, L. X. Gonzalez, V. de la Luz | | | Space Weather National Laboratory, Insituto de Geofisica, UNAM. | | | SPArToS (Spanish acronym for Solar Storms Arrival Prediction System) is an early-alert system to predict the arrival of coronal mass ejections and associated shock waves to Earth's neighborhood. Our system provides to the costumer the time and date at which a potentially dangerous CMEs and shocks would arrive to the Earth's neighborhood. The core of SPArToS is built over two pillars: (1) an analytic physics-based model called "Piston-Shock", which simultaneously approximates the trajectories of both CMEs and associated shocks; (2) and an empirical tendency that relates the initial inertial of CMEs with the conditions they evolve. Although the development of SPArToS formaly began by 2016; since the middle of 2015 the Piston-Shock model is used as an experimental tool for arrival-forecasting of CME/shocks. Since then up to now, the model's predictions have been regularly used by the Mexican Space Weather National Laboratory. | | 39 | Comparative analysis of solar radio bursts before and during CME propagation | Dididze, G et al. | p-Poster | | | G.Dididze, B.M. Shergelashvili V.V. Dorovskyy, V.N. Melnik, A.I. Brazhenko, S. Poedts, T.V. Zaqarashvili, M.Khodachenko | | | | | | The general context of the present paper is to perform a comparative analysis of type III solar and narrow-band type III like radio burst properties before and during the CME events, respectively. As is well known, the CME propagation often results in fragmentation of solar atmosphere on smaller regions of density/magnetic field enhancement/depletion. It is expected that this type of fragmentation may have radio signatures. In order to examine this intuitive expectation we perform comparison of usual type III bursts before the CME with narrow-band type III like bursts, which are observationally detectable on top of the background type IV radio bursts associated with the CME propagation.
The main goal is to analyze radio observational signatures of the dynamical processes in solar corona. In particular, to perform a comparison of local plasma parameters without and with CME propagation, based on the analysis of decameter radio emission data.
In order to achieve this goal, we focus on the analysis of, in total, 429 type III and 129 narrow-band type III like bursts. We study their main characteristic parameters such as frequency drift rate, duration and instantaneous frequency bandwidth using standard statistical methods. Furthermore, we infer local plasma parameters (e.g. density scale height, emission source radial sizes, etc.) using known definitions of frequency drift, duration and instantaneous frequency bandwidth.
The analysis reveals that the physical parameters of coronal plasma before CMEs considerably differ from those during the CMEs propagation (the observational periods 2 and 4 with type IV radio bursts associated with CMEs). Local density radial profiles and the characteristic spatial scales of radio emission sources vary with radial distance more drastically during the CME propagation, compared to the cases of quasistatic solar atmosphere without CME(s), observational periods 1 and 3.
The results of the work enable to distinguish different regimes of plasma state in the solar corona. Our results create a solid perspective for the development of novel tools for coronal plasma studies using radio dynamic spectra. | | 40 | Comparison of Proton and Electron Particle Acceleration at CME Driven Shocks | Parker, L et al. | p-Poster | | | Linda Neergaard Parker[1], Gang Li[2] | | | [1] Universities Space Research Association, [2] University of Alabama in Huntsville | | | We present results from a study of diffusive shock acceleration at interplanetary shocks using Particle Acceleration at Single Shocks (PASS) and Particle Acceleration at Multiple Shocks (PAMS) models. Both models solve the steady-state cosmic ray transport equation at an individual shock analytically to yield the diffusive shock acceleration (DSA) spectrum. We will use observations from the interplanetary satellites (e.g., ACE, STEREO) to characterize the upstream particle distribution and constrain/obtain the injection energy to explain the downstream accelerated particle distribution. We will address how the injection energy depends on the upstream particle distribution and how the resulting accelerated distribution is modified for a twin CME. Only those particles that exceed a theoretically motivated prescribed injection energy, E_inj, and up to a maximum injection energy (Emax) appropriate for quasi-parallel and quasi-perpendicular shocks (Zank et al., 2000, 2006; Dosch and Shalchi, 2010), are injected. Results from PASS/PAMS are then compared to observations at 1 AU. In addition to the acceleration of protons, we test the concept of electron acceleration at low injection energies for a single and multiple shock system using PASS/PAMS, using the same method as in Neergaard Parker and Zank, 2012 and Neergaard Parker et al., 2014. | | 41 | CME-driven shock and Type II solar radio burst band-splitting | Chrysaphi, N et al. | p-Poster | | | Nicolina Chrysaphi[1], Eduard P. Kontar[1], Manuela Temmer[2], Gordon D. Holman[3] | | | [1] University of Glasgow, [2] University of Graz, [3] NASA Goddard Space Flight Center | | | Shocks driven by Coronal Mass Ejections (CMEs) often accelerate electrons that emit radiation at radio wavelengths and produce slow drifting structures known as Type II solar radio bursts. We study a Type II burst observed by the LOw-Frequency Array (LOFAR) between 30-90 MHz. LOFAR is an international interferometer with high temporal, spectral, and spatial resolution and unprecedented imaging capabilities. We focus on the analysis of the Type II band-splitting, a characteristic referring to the splitting of a harmonic band into thinner lanes. Utilising LOFAR’s imaging, we compare for the first time, the emission source location of both band-split structures at the same moments in time. We consider the effect of radio propagation in the corona and obtain, for the first time, a quantitative estimation of the scattering effects on Type II sources. Our results show that the radially outward shifted sources cause the corona to appear denser than what it is and cause the lower frequency component of the split band to shift farther than the higher frequency component. Thus, the observed separation of the emission sources of the band-split structure is consistent with the true sources being co-spatial. | | 42 | Investigating the Magnetic Connection Between CME Source Regions and their ICME Counterparts | Lynch, B et al. | p-Poster | | | B. J. Lynch[1], M. D. Kazachenko[1,2], Y. Li[1], X. Sun[3], W. P. Abbett[1] | | | [1] Space Science Laboratory, Univ. of California-Berkeley, Berkeley, CA, USA, [2] Laboratory Atmospheric Space Physics, Univ. of Colorado, Boulder, CO, USA, [3] Institute for Astronomy, University of Hawaii, Honolulu, HI, USA | | | The magnetic flux content and magnetic helicity are fundamental physical properties that survive the Sun-to-1AU evolution of highly structured magnetic flux rope CME--ICME events. The standard CSHKP model for eruptive flares implies a quantitative relationship between the (unobserved) coronal magnetic reconnection process and the observable flare ribbons. The combination of photospheric magnetogram data with measurements of the lower-atmosphere flare ribbons allows us to derive the total unsigned reconnection flux and the reconnection rate. In three-dimensions, CSHKP eruptive flare reconnection simultaneously creates the post-eruption flare arcade of coronal loops and a highly twisted magnetic flux rope structure that is accelerated into the heliosphere. When flux rope ICMEs arrive at Earth they can lead to prolonged reconnection with the Earth’s magnetosphere and strong geomagnetic storms, particularly when the ICME field lines are oriented anti-parallel to the Earth’s magnetospheric field. Therefore it is of critical importance to space weather to understand the formation and orientation of flux-rope CMEs. The magnetic field dynamics of the flare arcade formation coincides with the observable step-wise change in the photospheric vector field orientation resulting in a Lorentz force impulse. Here we analyze a number of coronal source region properties of Earth-impacting magnetic cloud flux rope ICMEs. We examine the relationship between the Lorentz force impulse and reconnection flux to CME properties in the mid-to-extended corona such as mass, momentum, and kinetic energy and compare these to in situ properties of the ICME flux ropes such as size, handedness, field strength, orientation, flux and helicity. We will also discuss how recent MHD simulation results can help us understand these observational relationships.
This work is supported by NSF SHINE 1622495, NASA HSR NNX17AI28G, and the Coronal Global Evolutionary Model (CGEM) project NSF AGS 1321474. | | 43 | A case study of a coronal hole – CME interaction from the solar photosphere to Earth’s magnetosphere. | Heinemann, S et al. | p-Poster | | | Stephan G. Heinemann[1], Manuela Temmer[1], Astrid M. Veronig[1], Karin Dissauer[1], Stefan J. Hofmeister[1], Charlie Farrugia[2], Thomas Wiegelmann[3] | | | [1]University of Graz, Institute of Physics [2]University of New Hampshire [3]Max Planck Institute for Solar System Research | | | Understanding the evolution of coronal holes (CH) is a key towards a better understanding of solar wind high-speed streams and consequently their Space Weather effects. In this study we investigate the short term evolution of a CH and its associated high-speed stream together with the interaction of a nearby active region. From this active region a C7.7 flare event occurred on June 21, 2011 together with an associated CME that was Earth-directed. Using SDO data and magnetic field modeling we examine the surface properties of this event. A reconstruction of the CME has been done using multi viewpoint observations from SDO, STEREO-A and STEREO-B. To conclude the picture we investigate in-situ data at around 1 AU and geomagnetic indices near Earth. The influence of the HSS on the CME structure can already be observed from remote sensing white-light data as well as from in-situ data. By understanding the interactions and the relations between CHs and CMEs, we are able to conclude and advance the forecast of space weather effects. To improve the forecast capabilities is in great demand in the space weather community and this study is another step in reaching this goal. | | 44 | Magnetic field into the earth magnetic ramp and Mach number(M) variation co-relation at each angle between shock normal and upstream magnetic field $\theta$_Bn | Jivraj, P et al. | p-Poster | | | jjivraj pipaliya | | | sheffield university | | | One of the key aspects of the in-situ measurements of collisionless shocks is to identify the Quasi perpendicular shock(QPS) multi-parameters, such as sunward side 10.05R_E magnetopause resistive magnetic field region earth Magnetic ramp and Mach number variation at each angle between shock normal and upstream magnetic field in QPS front. It is argued that QPS front magnetic field variation into earth magnetic ramp δB/B_0 co-related to the Mach number(M) at each angle between shock normal and upstream magnetic field θ_Bn. This statistical probabilistic co-relation can be used as a proxy for space weather prediction | | 45 | Interplanetary Solar Radio Emissions observed by STEREO | Krupar, V et al. | p-Poster | | | Vratislav Krupar[1,2,3],Adam Szabo[2],Robert MacDowall[2] | | | [1]USRA, Columbia, MD, USA[2]NASA-GSFC, Greenbelt, MD, USA[3]IAP-CAS, Prague, Czech Republic | | | Interplanetary type II and type III radio bursts are generated by electron beams of accelerated at shock waves ahead of coronal mass ejections, and at reconnection sites of solar flares, respectively. Here, we report a statistical analysis of type II and type III radio bursts observed by Solar TErrestrial RElations Observatory (STEREO)/Waves instruments (125 kHz - 16 MHz) between May 2007 and September 2014. Our results indicate that type II radio bursts are preferably observed at higher frequencies, when compared to type III radio bursts. The flux density of type II bursts is statistically frequency independent, while the flux density of type III bursts is larger for the lower frequencies. We also study relations of exponential rise and decay times of type III radio bursts with a focus on scattering of radio emissions by density inhomogeneities in the solar wind. |
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