ESWW11 - Session

Session - Solar activity as a driver for space weather and space weather modelling

Matthew West, Shaun Bloomfield

Space weather forecasting is frequently driven by the end observational products of solar activity (flare emission, CMEs and energetic particles). This is reflected in other sessions at this meeting, where inputs are used to develop forecasting tools, in order to look at the influence of the Sun on the interplanetary medium and Earth. Few sessions have been dedicated to investigating the physics underpinning solar activity, even though such work is important for understanding why, where and when flares and CMEs might occur. Such understanding is key to forming rigorous empirical and physics-based space weather forecasting tools.
There are a number of ways that the Sun influences changes in space weather on the short term (hours-days). These include changes in the structure of the corona (coronal holes, streamers, psuedostreamers etc), variations in irradiance, more dynamic events such as flares and eruptions, the emergence of active regions, etc. In this session we aim to present a broad spectrum of research on topics that have an impact on space weather conditions, and how they feed into models used in space weather prediction. We encourage the community to present new observations and models that might help to further our understanding of the causes and drivers of solar activity, and how these observations may lead toward the next generation of forecasting tools.

Talks and First Class Posters
Monday November 17, 14:00-15:30, 16:00-18:00, auditorium Reine Elisabeth

Poster Viewing
Monday November 17, 15:30-16:00, area in front of auditorium Reine Elisabeth

Talks

Oral - invited	2:00 pm	Observing Cycles, Seasons, and Storms
		McIntosh, S
		NCAR/HAO
		Recent observational findings suggest that the 11(-ish) solar sunspot cycle is a pattern resulting from the interaction, or interference, of large scale magnetic field bands that evolve within the Sun’s convective interior over it’s 22-year magnetic polarity reversal cycle. These toroidal magnetic bands are anchored deep in the solar convection zone and migrate from high latitudes to the equator over 22 years, and new analysis techniques have allowed us to trace their migration from birth to death. We will see that the spatio-temporal interaction of these magnetic bands helps us frame the landmarks of the sunspot cycle with a surprising realization that, once considered, permits a deeper look into the gross energetics of the star, its radiative, particulate and eruptive output and how they vary with time. It is possible that, with refinement and an ongoing commitment to synoptic observational programs, these results offer greatly improved forecast skill on monthly, annual and decadal timescales while a comprehensive physical model can be developed.
Oral	2:30 pm	Analysis of Solar Wind Sources during the Rising Phase of Solar Cycle 24 based on the AIA/SDO EUV Images
		Shugay, Y¹; Slemzin, V²
		¹Lomonosov Moscow State University Skobeltsyn Institute of Nuclear Physics; ²Lebedev Physical Institute of Russian Academy of Sciences
		The parameters of solar wind (SW) measured in the near-Earth space depend on type and position of coronal sources, on the level of solar activity, also taking into account probable distortion in the heliosphere due to interaction of various types of SW. This work presents the results of analysis of the SW sources during the rising phase of the solar cycle 24 (2010-2012) in a relationship with the parameters of the associated SW flows near Earth such as velocity, flow density and ion composition. The coronal sources prominent in this period - coronal holes, small areas of open magnetic fields near active regions and transient sources associated with solar activity have been investigated using the EUV solar images at different wavelengths obtained by AIA/SDO as well as the magnetograms obtained by HMI/SDO. In order to evaluate the impact of different coronal sources on the SW speed, the obtained relationships were used in the empirical SW models, and then the results were compared with measurements. The results of this study can help to improve the accuracy of the space weather forecast. The research leading to these results has received funding from the European Commission's Seventh Framework Programme (FP7/2007-2013) under the grant agreement eHeroes (project n° 284461, www.eheroes.eu).
Oral	2:45 pm	Five years of EUV Solar Irradiance Evolution, from Short to Long Timescales as Observed by PROBA2/LYRA
		Dominique, M¹; Dammasch, I¹; Wauters, L¹; Katsiyannis, A¹; Ryan, D¹
		¹Royal Observatory of Belgium
		With important questions such as the climate changes and the role of the Sun debated by the scientific community, it appears crucial to measure the evolution of the solar spectral irradiance. This is especially the case in the soft X-ray - extreme UV range, which shows the highest variability and impacts the Earth's ionosphere on both long (background emission evolution) and short (flares) timescales. LYRA, the Large Yield Radiometer on-board PROBA2 has been observing the Sun for five years, making observations in four broadband channels in the EUV-to-MUV range, accumulating quasi-uninterrupted time series. Additionally, LYRA benefits from a good signal-to-noise ratio and a high acquisition cadence, which make it a good instrument for flare observations. We will present five years of evolution of the EUV solar emission as observed by LYRA, focusing first on the longer timescales, for which the effects of the instrumental degradation must be taken into account, then moving to shorter timescales and the observation of flares.
Oral	3:00 pm	Rising of the 24th solar cycle with PREMOS/PICARD and COSIR
		Cessateur, G¹; S., A¹; Schmutz, W¹
		¹PMOD/WRC
		The knowledge of the spectral solar irradiance and its variation in time is a key problem for solar physics, space weather as well as for space climate. We present here a new model of solar irradiance variability, COSIR for Code Of Solar Irradiance Reconstruction. Based on the assumption that the variability is triggered by the solar surface magnetism, we consider four types of active features such as sunspot umbra and penumbra, active network and faculae. The disc area coverages of these features have been deduced from the segmentation of solar magnetograms and solar images as provided by the HMI instrument onboard SDO. Spectra of active regions and the quiet Sun have been calculated with the radiative transfer code COSI. COSIR calculations are then directly compared with PREMOS observations in the UV and visible spectral ranges. Model and observations are in excellent agreement for rotational variability, longer-term variations being out of reach of the PREMOS instrument. We will also show that sunspots are not required to reconstruct the solar variability in the UV, while faculae plays an important role in the visible.
Oral - Invited	4:00 PM	Initiation of Solar Eruptions Combining Models and Observations
		Poedts, S.
		KU Leuven
		Coronal mass ejections (CMEs) are important drivers of the space weather. Therefore, most studies focus on the fastest and thus most dangerous ICME events. However, the `typical' or average CME propagates at a velocity only slightly higher than the slow solar wind speed and, especially during solar minimum, fast CMEs are in fact rather exceptional. Yet, also the magnetic clouds associated to the slower CMEs are recognized to be able to cause significant geomagnetic disturbances. We will discuss 2.5D (axi-symmetric) and 3D self-consistent numerical magnetohydrodynamics (MHD) models for the onset of CMEs under solar minimum conditions, and for their interaction with coronal streamers and subsequent evolution up to 1AU. The CMEs are initiated by magnetic flux emergence/cancellation and/or by shearing the magnetic foot points of a magnetic arcade which is positioned above or below the equatorial plane and embedded in a larger helmet streamer. The overlying magnetic streamer field then deflects the CMEs towards the equator, and the deflection path is dependent on the driving velocity. The core of the CME, created during the onset process, contains a magnetic flux rope and the synthetic white light images often show the typical three-part CME structure. Observations are used to constrain the models by providing initial and boundary conditions. These solar observations, as well as the resulting characteristic plasma parameters they produce at 1AU compared to (ACE) observations, provide excellent tools to validate the models. The current state-of-the-art will be reviewed.
Oral	4:30 pm	Flux Rope Formation and Eruption: the Physical Processes Underlying Coronal Mass Ejection Occurrence
		Green, L¹; Baker, D¹; Yardley, S¹; David, L¹; Kliem, B²
		¹UCL-MSSL; ²University of Potsdam
		Coronal mass ejections (CMEs) are an important driver of major space weather events at Earth and monitoring their occurrence is a routine aspect of space weather forecasting. However, end users of space weather products are interested in reliable forecasts that are delivered with as long a lead-time as possible. So, moving beyond current state-of-the-art involves understanding when a CME will occur, how it evolves after eruptions and whether it is likely to have a magnetic configuration that will make it geoeffective when it reaches the Earth. This talk will discuss the science behind the occurrence of CMEs from solar active regions. In particular, the observational identification of twisted magnetic field configurations, known as flux ropes, using a range of imaging and spectroscopic techniques will be covered. The observations suggest that active region flux ropes are stable on the Sun for only a few hours before they erupt as a CME, in line with the latest theoretical and modelling expectations.
Oral	4:45 pm	Observational Characteristics of CMEs without Low Coronal Signatures
		D'Huys, E¹; Seaton, D¹; Poedts, S²
		¹Royal Observatory of Belgium; ²Centre for Mathematical Plasma-Astrophysics - KULeuven
		Solar eruptions are associated with a variety of phenomena occurring in the low corona before, during, and after onset of eruption. These phenomena include changes in magnetic configuration, flows, solar flares, the formation of post-flare loop arcades, EUV waves, and coronal dimmings. Though easily visible in coronagraph observations, so-called stealth coronal mass ejections (CMEs) do not obviously exhibit any of these low-coronal signatures. The presence or absence of distinct coronal signatures can be linked to different theoretical models to establish the mechanisms by which the eruption is initiated and driven. To identify these CMEs without low coronal signatures, we compare CMEs from the CACTus catalog to the output of SoFAST (Solar Flare Automated Search Tool) based on observations from PROBA2/SWAP. Using STEREO observations, we can exclude the back-sided CMEs. Also GOES, AIA, EUVI and SWAP data are used to exclude any associated low coronal signature of eruption. As a result, 40 CMEs without low coronal signatures, occurring in 2012, are identified. Their observational and kinematic properties are analyzed and compared to those of regular CMEs.
Oral	5:00 pm	Analysis of a C4.1 Flare Occurred in a δ Spot using SDO and SST Data
		Guglielmino, S L¹; Zuccarello, F²; Romano, P³; Cristaldi, A⁴; Falco, M²; Ermolli, I³; Criscuoli, S⁵;
		¹Università degli Studi di Catania; ²Dipartimento di Fisica e Astronomia – Università di Catania, Italy; ³INAF – Osservatorio Astrofisico di Catania, Italy; ⁴Dipartimento di Fisica– Università Roma Tor Vergata, Italy / INAF – Osservatorio Astronomico di Roma, Italy; ⁵NSO – National Solar Observatory, Sunspot, USA
		δ spots are characterized by umbrae of opposite polarities sharing a common penumbra. They usually host several activity phenomena and are often the sites where major flares occur. Active region NOAA 11267 (AR 267) hosted a flare-productive δ spot in the leading polarity. We analyze SDO observations, using both HMI Stokes measurements and AIA filtergrams, to study the magnetic configuration and the trend of magnetic helicity flux during the evolution of the AR 267 and to characterize the flares that occurred in the δ spot during this period. In particular, we study the C4.1 flare occurred in the AR 267 on August 6, 2011. We also benefit from high-resolution observations acquired at the Swedish 1-m Solar Tower (SST), which cover the decay phase of this flare after 20 minutes from the peak. This dataset consists of both photospheric measurements along the profiles of the Fe I lines at 630.25 nm and 557.6 nm and filtergrams in the core of the chromospheric Ca II H line at 396.8 nm. The results obtained from this analysis are presented in the framework of solar activity as a driver for Space Weather. This research work has received funding from the European Commissions Seventh Framework Programme under the grant agreements no. 284461 (eHEROES project), no. 312495 (SOLARNET project), no. 606862 (F-Chroma project). This research is also supported by the ITA MIUR-PRIN grant on "The active sun and its effects on space and Earth climate" and by Space Weather Italian COmmunity (SWICO) Research Program.
Oral	5:15 pm	Predictive Science of Coronal Mass Ejection
		Schmieder, B¹; Aulanier, G¹
		¹Observatoire de Paris
		3D standard MHD models of flare and CME are well developed showing how catastrophic events may occur (Aulanier et al 2010) . Coronal mass ejections (CME) are associated with the formation of a twisted flux rope followed by its eruption. Solar observations can give indications on the formation, the configuration, and the eruption process of CMEs. Sigmoids, for example, can be used as direct observations of twisted flux ropes in the corona before an eruption. They are detectable in X-rays and in UV emission (Hinode/XRT, SDO). Also, topology analysis using vector magnetograms (THEMIS, HMI) is a good tool to show the reconnection points and/or the 3D large hyperbolic volumes where reconnection can occur due to the presence of quasi-separatrix layers (QSLs). The magnetic helicity sign of the flux rope is related to the characteristic parameters of the active region source of the CME and the subsequent magnetic cloud in the interplanetary medium. Examples of observations will be presented and discussed in the framework of the 3D standard MHD model for prediction.
Oral	5:30 pm	On the February 14-15, 2011 CME-CME interaction Events and Consequences for Space Weather
		Temmer, M¹; Veronig, A²; Peinhart, V²; Vrsnak, B³
		¹University of Graz; ²Institute of Physics, University of Graz; ³Hvar Observatory, University of Zagreb
		The interaction of CMEs with other CMEs alters their characeristics in terms of an increase of their internal magnetic field due to compression or changes in their speeds. Interacting CMEs are believed to cause the most severe Space Weather events. Keeping in mind the daily occurrence rate of CMEs, interaction processes are expected to occur on a rather frequent basis. Therefore, it is important to enhance our knowledge on CME-CME interaction processes. We present a detailed analysis on the CME-CME interaction event from February 14-15, 2011 by combining remote sensing data and 3D reconstruction techniques. We derive differences between the interacting CME flanks and the apexes. We conclude that it is primarily the speed and magnetic structure or geometry of a CME which controls the interaction process.

Posters

Note: the numbering in this table can differ from the numbering in the main overview .

1	Poster	Improving solar 11yr magnetic cycle prediction by using variational data assimilation in a mean field dynamo model
		Hung, Ching-Pui¹; Jouve, L²; Brun, A S¹; Fournier, A³
		¹AIM, CEA Saclay; ²IRAP, Observatoire Midi-Pyrennées; ³IPGP
		We present our recent effort to implement modern variational data assimilation techniques into a 2.5 D mean field solar dynamo code. This work extend the work of (Jouve et al. 2011, ApJ) to take into account the correct spherical geometry and meridional circulation into so-called Babccok-Leigthon flux transport dynamo models. Based on twin-experiments, in which we observe our dynamo simulations, and on a well defined cost function using toroidal and poloidal field observations we are able to recover the main attributes of the dynamo solution used to test our data assimilation algorithm. By assimilating solar data (such as Wolf number or butterfly diagram) we are starting to deduce the profile and temporal variations of key ingredients of the solar dynamo. We find that the data sampling and the temporal window are key to get reliable results. We show how such powerful technique can be used to improve our ability to predict the solar magnetic activity.
2	Poster	Predicting Flaring Activity through Supervised Classification on Predictor Variables
		Delouille, V¹; De Visscher, R¹
		¹STCE/Royal Observatory of Belgium
		Recent years have seen a resurgence in the field of solar flare prediction. Most of these methods aim at evaluating a flare probability in the next 24h based on the current or past status of an active region. In this project sequences of magnetogram and continuum images are used to distinguish active regions with strong flaring activity. A homogeneous dataset of magnetogram and continuum images of active regions in their growth phase is produced. These images are summarized into various scalar predictor variables, which are used as the input for the supervised classification methods. These methods take into account the time evolution of the active regions through lagged values of the predictors. The performance of various supervised classification algorithms as well as the predictive power of each predictor variable are assessed. Special care is taken to handle the imbalance between the number of active regions with and without strong flaring activity. In this presentation I will discuss preliminary results from this project.
3	Poster	Detection of coronal holes and filament channels in SDO/AIA 193Å images via geometrical classification methods
		Reiss, M¹; Temmer, M¹; Rotter, T¹; Hofmeister, S¹; Veronig, A¹
		¹University of Graz, Institute of Physics
		It is well known that coronal holes play an important role in geomagnetic storm activity. They coincide with rapidly expanding open magnetic fields and are the source regions of the high speed solar wind streams. Due to the lower temperature and density compared to the ambient coronal plasma, coronal holes appear as dark areas in X-ray and extreme-ultraviolet (EUV) images of the Sun. In a previous study, we presented an automated method for the identification and extraction of coronal hole regions in SoHO/EIT 195Å images. For a case study, the method was also successfully applied to PROBA2/SWAP 174Å data. Currently it is used on SDO/AIA 193Å data for the automatic extraction of coronal hole areas and forecasting of solar wind speed at 1 AU. The testing phase demonstrated that filament channels are sometimes identified by the algorithm as coronal holes, which leads to errors in the forecasts of high-speed solar wind streams. To improve the solar wind forecasting method we need to distinguish filament channels from coronal holes. Although previous research has been carried out on this subject, no study exists which pays attention to the intrinsic geometry of these features. Based on differences in their topology, we investigate the benefit from geometrical classification methods for improving the distinction between coronal holes and filament channels. Using SDO/AIA 193Å image data, we present two new geometrical classification methods in comparison with well known shape measures from literature. The results of this research support the idea that geometrical methods have the potential to decrease coronal hole classification errors and could be used as an applied screening technique in our solar wind forecast algorithm.
4	Poster	Real-time forecasting of solar wind high-speed streams
		Veronig, A¹; Rotter, T¹; Temmer, M¹; Hofmeister, S¹; Reiss, M¹; Vrsnak, B¹
		¹University of Graz
		Coronal holes are regions of low density and temperature compared to the surrounding corona, and thus appear dark in solar EUV and X-ray images. They are associated with rapidly expanding “open” magnetic fields, and are the source of high-speed solar wind streams (HSSs). HSSs shape the solar wind distribution in interplanetary space and are the dominant contribution to space weather disturbances at times of quiet solar activity. We present an empirical model based on the instantaneous area covered by coronal holes close to the central meridian, in order to predict the solar wind speed at 1 AU with a lead time up to four days in advance. The method uses an intensity-based thresholding techniques applied to SDO/AIA 193 Å images and an automatically adapting relation between coronal hole area and solar wind speed based on the three preceding Carrington Rotations. For the period under study (10/2010–12/2014), the correlation obtained between predicted and in-situ measured HSS velocity peaks is c= 0.7. The algorithm is regularly applied in real-time HSS forecasting, being hourly updated with the most recent SDO/AIA 193 Å image (http://swe.uni-graz.at/solarwind). In a recent improvement step, solar magnetic field information by SDO/HMI is included to predict the HSS geomagnetic storm activity, which is governed by the solar wind speed v and the southward magnetic field component Bz.
5	Poster	Studies of Coronal Hole Properties and Geomagnetic Forecasts during the Current Solar Cycle
		Tassev, Y¹; Abunina, M²; Abunin, A²; Belov, A²; Gaidash, S²; Tassev, Y³; Velinov, P I Y³; Mateev, L³; Tonev, P³
		¹Space Research and technology institute; ²Institute for Geomagnetism, Ionosphere and Radiowave Propagation (IZMIRAN), Russian Academy of Sciences, Troitsk, Moscow Region; ³Institute for Space Research and Technology, Bulgarian Academy of Sciences Acad. G. Bonchev Str., Bl. 1, 1113 Soﬁa, Bulgaria
		Introduction. The coronal holes are sources of high-speed flows of solar wind, and, in its turn, are one of the main sources of geomagnetic disturbances. The coronal holes differ very much one from another and their geo-effectiveness varies in a wide range. In this paper we implement a study to answer the question how the coronal holes characterized by different location on the Sun and by their polarity influence the geomagnetic activity. Data and methods. The data base for Forbush-effects and interplanetary disturbances developed in the Institute for Terrestrial Magnetism, Ionosphere and Propagation of Radio-waves of Russian Academy of Sciences (IZMIRAN) is used by us in order to choose events in which the coronal holes have influence on the Earth’s magnetosphere. Generally 53 events in the period 2011-2012 were chosen, such that a well recognized coronal hole was the source of geo-effectiveness in each case. We considered the coronal holes with respect to their polarity and the location on the solar disk. The enumeration and location of the coronal holes are obtained from the site http://www.solen.info/solar/coronal_holes.html and the polarity is retrieved from data taken from http://www.solen.info/solar/old_reports/. The considered 53 coronal holes (CH) observed in the period 2011-2012 of solar cycle 24 are separated into groups by the solar latitude and their polarity. We found 12 coronal holes of negative polarity in the northern solar hemisphere; 16 CH of positive polarity in the southern solar hemisphere; 21 CH crossing the equator (19 of them - of negative polarity, and only 2 – of positive polarity); and 4 untypical CH (3 of them of negative polarity in the southern hemisphere, and one of positive polarity in the north hemisphere). Discussion of the results. A conclusion is made that: 1. The trans-equatorial group is the most effective one, and that almost all coronal holes in this group have a negative polarity. 2. Less, but yet sufficiently effective, are the holes of negative polarity at north latitudes and those of positive polarity at south latitudes. 3. The much smaller number of coronal holes of opposite polarity (CH of negative polarity in south hemisphere and CH of positive one in north hemisphere) are less effective. The obtained results give a better idea for coronal hole geo-effectiveness. At the same time, these results will help us for space weather prediction.
6	Poster	Solar Demon: Real-Time Flare, Dimming and EUV Wave Monitoring
		Kraaikamp, E
		Royal Observatory of Belgium
		Flares, Dimmings and EUV waves are closely associated with coronal mass ejections (CMEs), and therefore provide useful information for early space weather alerts. Detection and characterization of these events can be used to gain better understanding of underlying physical mechanisms. For front side CMEs, the associated dimming and EUV wave provide extra information, which can yield improved estimates of the geo-effectiveness and possible arrival time of the CME. Solar Demon has been designed to detect and characterize flares, dimmings as well as EUV waves in near real-time on Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) data. It is running continuously at the Royal Observatory of Belgium, and is the result of collaboration between the FP7 projects COMESEP and AFFECTS. As a dedicated module in the automatic COMESEP alert system, Solar Demon provides flare locations which are used to predict the impact of Solar Energetic Particle (SEP) events. We present an overview of the Solar Demon system, and in more detail we show the EUV wave monitor and the resulting event catalog, containing information on EUV waves (direction, speed, acceleration) for all detected events since May 2010.’
7	Poster	The multiscale magnetic pattern and the roots of solar activity
		Berrilli, F¹; Scardigli, S¹; Del Moro, D¹
		¹University of Rome Tor Vergata
		The plasma turbulent flows in the solar photosphere control the motion of magnetic elements. These elements are arranged, on the solar surface, in a multiscale magnetic pattern. Their motion modifies the topology of magnetic field and excites many MHD modes. Actually, photospheric turbulent motions move such footpoints of magnetic loops causing the field to get twisted and storing up energy. For these reasons they can be identified as the roots of solar activity which are at the basis of space weather phenomena. The analysis of such magnetic patterns paves the way for the investigation of all turbulent convective scales, from granular to global. In particular, to address the question of magnetic structures driven by turbulent convection in the granular -supergranular range, a voids detection method applied on HINODE and MDI magnetograms is used. The computed distribution of associated length scales shows a quasi-exponential behavior at scales between 2 and 60 Mm. The monotonic distribution and the lack of marked features in such a range points out the absence of distinct scales (e.g., mesogranulation, supergranulation) and supports the multi-scale hypothesis of convective motion flows at the solar surface (Nordlund et al., 2009; Yelles Chaouche et al., 2011; Berrilli et al., 2013).
8	Poster	A Flare Forecasting Algorithm Based on Multi-Line Magnetograms
		Berrilli, F¹; Loumou, K¹; Jefferies, S²
		¹University of Rome Tor Vergata; ²IfA - University of Hawaii
		The ability to monitor and forecast the environmental conditions in near-Earth space (space weather) is of paramount importance to the European society. Sudden changes in space weather, due to eruptive events on the Sun such as coronal mass ejections and flares, can impact the technology we rely on every day. The MOTH instrument, based on commercial magneto-optical filters and optics, is able to perform multi-line, high-cadence synoptic observations of the Sun and solar activity. The result is a spectral imaging system that has up to 10 times greater stability than the best Fabry-Perot interferometers, thus taking us a step closer to accurate monitoring of space weather. We present preliminary analysis of multi-line magnetograms used to test a flare forecasting algorithm.
9	Poster	High-Frequency Quasi-Periodic Pulsations (QPP) in Solar Flares, as Observed by PROBA2/LYRA
		Dominique, M¹; Dolla, L¹; Zhukov, A¹
		¹Royal Observatory of Belgium
		Sub-minute quasi-periodic pulsations have been reported in the impulsive phase of several solar flares in wavelengths ranging from radio waves to Hard X-Ray. However, their detection remains challenging as observations with a good signal-to-noise ratio and a high acquisition cadence are required. LYRA, the Large Yield Radiometer onboard PROBA2 has a signal-to-noise ratio and a high acquisition cadence enabling it to observe sub-minute QPPs and can therefore provide new insights on this topic. In this poster, after a review of our current understanding of those QPPs, I will discuss how they can help us understand the flaring process and flare environment. I will then present our latest results and ongoing investigations made with LYRA.
10	Poster	Multi-Scale Percolation of Magnetic Energy and Currents as Mechanism of Flare Energy Release
		Pustilnik, L¹; Ikhsanov, N²; Beskrovnaya , N²
		¹Tel Aviv University, Israel Space Agency and Golan Research Institute, Israel; University ITMO, Russia; ²Central Astronomical Observatory of the RAS at Pulkovo, St. Petersburg, Russia; Saint-Petersburg State University, Russia
		We consider the approach to pre-flare equilibrium of magnetic structure above active region, with taking into account existence of “magnetic skeleton” - system of numerous very thin magnetic threads with almost constant cross section from photosphere to corona, observed during last years on UV, soft X-ray and optical lines. We show that existence of observed magnetic skeleton with very strong magnetic fields. Dominated on coronal level contradicts to all accepted force-free approach (described diffused magnetic fields dispersed in corona). This system of thin magnetic threads with strong interacting between them supplied percolation of magnetic stresses from photosphere to corona is new element of magnetic equilibrium and may be source of catastrophically transition to flare phase with fast magnetic energy dissipation in formed thin turbulent current sheets. We show that accumulation of magnetic energy in active region with next discharge it during solar flares may be considered as global three-level percolation of the thermal, kinetic and magnetic energy through three scales of networks. These networks are consisting of strongly interacting elements with elements self-organization: 1. Mega-percolation of the thermal, kinetic and magnetic energy through the convective zone with formation of universal power-like spectrum (partly for of the magnetic energy, stored in the active regions); 2. Macro-percolation of magnetic energy and tension via thin current-magnetic treads from the photosphere to corona with formation of universal power-like amplitude spectrum of the flares itself; 3. Micro-percolation of global currents of the active region through the unstable thin turbulent current sheet of flare with formation resistors network and formation of both the amplitude spectrum and the energy spectrum of particles accelerated in the electric fields of numerous double electrostatic sheets in this current sheet. This approach allow to universal power-like statistics (both in amplitude of flares and spikes, and energy spectrum of accelerated solar cosmic rays, observed in solar and stellar flares.
11	Poster	An Experimental Bases for the Creation of Radioastronomical Method of Short-Term Coronal Mass Ejections Forecasting
		Sheiner, O¹; Fridman, V¹
		¹Radiophysical Research Institute
		Space weather forecasting is an emerging science that is facing many tasks. Some of them are the definition, classification and representation of solar features and the establishing an accurate correlation between the occurrence of solar activities (e.g., solar flares and CMEs) and solar features observed in various wavelengths. Recent solar researches lead to the concept of general approach to solar active events: CMEs are global phenomenon of solar activity caused by the global magnetohydrodynamic processes. These processes occur in different ranges of emission, primarily in the optical range and the microwave emission being generated near the surface of the sun from a total of several thousand kilometers. The procedures of CMEs’ phenomena prediction must be built taking into account all these features. The usage of radio-astronomical data for CMEs prediction in this sense is convenient and prospectively. It is so, because, the majority of the proceeding processes, as a rule, is reflected in the radio emission; spectral measurements cover all heights of solar atmosphere, sensitivity and accuracy of measurements make it possible to record even small energy changes. Registration of the radio emission is provided by virtually all-weather ground-based observations, and there is the relative cheapness to obtain the corresponding information due to a developed system of monitoring observations. Previously it was established by the authors (for the events of XXIIIrd eleven-year solar activity cycle) that a significant number of coronal mass ejections in a two‐hour interval before their recording by coronagraphs are preceded by sporadic radio emission that can be defined as radio precursors of coronal mass ejections. Dynamics of sporadic radio emission components, prior to CMEs’ registration on coronagraph, has been analyzed on the ascending branch of the XXIVth solar activity cycle. The results confirmed the previously discovered spectral and temporal characteristics of solar radio emission, that allows us to formulate recommendations for short-term forecasts of CMEs phenomena on the basis of statistical regularities of radio data.
12	Poster	Origin of Space Weather Candidates in the Solar Atmosphere
		Dwivedi, B N¹; Srivastava, A K¹
		¹IIT (BHU)
		The understanding of the origin of space weather candidates (solar flares, CMEs and associated eruptions) in the solar active regions are crucial to predicting their heliospheric consequences. The localized energy build-up and its release processes play a significant role in the occurrence of such dynamical plasma processes that entirely depend on magnetic field conditions and their dynamical evolution. We discuss the origin of these space weather candidates, e.g., flux emergence and complexity of the fields, MHD instabilities making use of novel observations and associated physical mechanisms.
13	Poster	Sporadic and Recurrent Effects in Cosmic Ray Intensity in Solar Minimum
		Kryakunova, O¹; Belov, A²; Abunin, A²; Abunina, M²; Eroshenko, E²; Malimbayev, A¹; Tsepakina, I¹; Nikolayevskiy, N¹; Yanke, V²
		¹Institute of Ionosphere; ²Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation (IZMIRAN)
		Features of the Forbush-effects caused by high-speed solar wind streams from low-latitude coronal holes and coronal mass ejections are described. Behavior of the mean characteristics by all the Forbush-effects in 2007 caused by coronal holes (interplanetary magnetic field intensity and solar wind velocity, 10 GV cosmic ray density and equatorial component of the cosmic ray anisotropy) is calculated by epoch method. Effects of high-speed solar wind streams from low-latitude coronal holes and coronal mass ejections on cosmic ray intensity in 2007 are studied using the database on Forbush effects created at IZMIRAN. Cosmic ray density and anisotropy were calculated by the Global Survey Method (GSM) on the basis of Neutron Monitor network data.
14	Poster	Towards the Analysis and Communication of Flare Probabilities in Terms of the Probability Density Distribution.
		Andries, J¹; Devos, A¹; Verbeeck, F¹; Berghmans, D¹
		¹Royal Observatory of Belgium
		Flare probabilities, be it per active region or for the full solar disc, are classically predicted and communicated in terms of 3 probability values for the 3 flare classes C, M and X respectively. Communicating flare probability estimates solely in terms of these three values limits the usefulness of the information to the end user and influences the conception and validation of prediction methods. With respect to the validation, the condensed information leads to a binary approach based on hit or miss statistics [1,2]. While these methods can be extended with the use of score matrices which can then be customized to the users needs (e.g. penalize missed occurrences harder than false alarms), these must be ran individually for each set of user requirements (score matrices). Above all, these validation exercises are only providing longer term statistics allowing a customer only to judge how well the predictions are performing for his/her needs in the long run. But given a certain prediction on a given day, the condensed way in which the probability information is communicated, does not provide any information on the reliability of that particular forecast. Moreover, the information which is communicated is insufficient to allow users to distill the more appropriate tailored information they may need. In this work we proceed towards another way of producing and communicating flare probabilities, which is employing the full probability density distribution. The probability density distribution is the function that indicates the probability that a flare of a specific X-ray flux or higher will occur within a predefined time range. By binning the continuous X-ray flux values- one obtains the probabilities for the classic C, M and X flare levels but also for any other appropriate (e.g. more detailed) categorization. However, the advantage is more than just increased resolution. An obvious alternative way to communicate the probabilities which is enabled by this method is to extract a number of the percentiles (e.g. 10%, 25%, ...). The 50% percentile would just represent an increased resolution equivalent of the current statements "C, M, or X level flares expected" e.g. "50% chance on flares of M3 level or higher". But more importantly, the confidence of the forecaster in the prediction is quantified by the relative distance between the percentile levels. The evaluation of the performance of such probabilistic prediction method can by no means be based on hit and miss statistics. The probability distribution function and as such the percentile levels are exactly defined by the number of events, and it is a prerequisite to the method that the longer term statistics and skill scores are met. The performance of one method over another should rather be judged by the variation of the percentile curves (as function of time) around the long term average percentile level, and in particular on the ability of the method to keep the percentile levels as close together as possible. [1] http://www.swpc.noaa.gov/forecast_verification/ [2] http://www.sidc.be/forecastverification/index.php
15	Poster	Fast Magnetic Reconnection: the Trigger for CMEs
		Pucci, F¹; Berrilli, F¹; Velli, M²; Scardigli, S¹;
		¹Università di Roma Tor Vergata; ²UCLA
		Coronal Mass Ejections(CMEs) and flares are caused by relaxation of energy stored in the Sun's magnetic field. The energetic particles emitted in connection with CMEs and flares cause damages to satellites, and in extreme cases the perturbations of the Earth's magnetic field lead to inductive effects that can damage power plants on the ground. Therefore it is very important for modern technologies to understand the physical processes behind these phenomena; understanding the triggers to energy release in energetic solar events is a fundamental piece of the space weather puzzle. It is widely accepted that magnetic reconnection in the solar atmosphere plays a crucial role in CMEs and flares, the longstanding question having been to speed up reconnection to the timescales of minutes/hours of observed energy release. We have studied the linear tearing mode of current sheets, assuming that coronal evolution allows them to thin with time. By examining sheets with thicknesses scaling as different powers of the magnetic Reynolds number $S$, we have shown that the growth rate of the tearing mode increases as current sheets thin and, once the thickness reaches a scaling $a/L sim S^{-1/3}$, reaches the ideal limit i.e. the time for the instability to develop is of the order of the Alfvén time. That means that a fast instability sets in well before Sweet-Parker type current sheets can form and may provide a trigger mechanism for coronal energy release. In addition, such an instability produces many islands in the sheet, leading to a fast nonlinear evolution and most probably a turbulent disruption of the sheet itself. This has fundamental implications for magnetically driven reconnection throughout the corona, and in particular to the initiation of coronal mass ejections, all of which are of interest to the space-weather program. In this poster we summarize the theory and provide a phenomenological guide to possible observational aspects of space weather events.
16	Poster	Solar Flare Forecasts, Based on SDO Solar Magnetic Field Observations and Knowledge about Extreme Events
		Lundstedt, H¹; Persson, T²
		¹Swedish Institute of Space Physics; ²Center for Mathematical Sciences, Lund University
		We give a progress report on the development of daily forecasts of solar flares for the RWC-Sweden of International Space Environment Service (ISES). As input to the model we use measurements by Solar Dynamics Observatory (SDO) of magnetic field complexity and derived parameters of the Stanford Space-weather HMI Active Region Patches (SHARP). Examples and forecasts are presented. However, since the most pressing space weather forecasts are those of the most intense solar flares we also separately study extreme solar storm events. By now we have studied the extreme solar storms in May 1921, November 2003 and July 2012. What makes a moderate to severe solar storm become an extreme solar storm? How to model it? These questions are discussed.
17	Poster	Magnetic Helicity Flux and Flare Sites in Active Region NOAA 11283
		Romano, P¹; collaboration, SWICO²
		¹INAF; ²Università di Catania, Università di Roma Tor Vergata, Università della Calabria, Università degli Studi di Firenze, INGV
		We analyzed the magnetic helicity flux in the Active Region NOAA 11283, where several M and X GOES-class flares and several CMEs occurred. We analyzed the full-disk line-of-sight magnetograms acquired by HMI/SDO at 6173 A from Sept. 5, 2011 at 00:00 UT to Sept. 8, 2011 at 22:24 UT and AIA/SDO images at 171 and 304 A to focus on the X2.1 flare and the associated sigmoid eruption, which began at 22:12 UT and peaked at 22:20 UT on Sept. 9, 2011. This analysis provides a further evidence that this strong flare and the corresponding CMEs may be due to the interaction between magnetic systems characterized by opposite sign of magnetic helicity flux. In particular, we observed a peculiar rotation of a sunspot where a filament and the overlying arcade involved in the eruption were partially rooted. We believe that a considerable amount of magnetic helicity was transported to the corona during the sunspot rotation, playing an important role in twisting and destabilizing the filament-flux rope system. This research work has received funding from the European Commissions Seventh Framework Programme under the grant agreements no. 284461 (eHEROES project), no. 312495 (SOLARNET project), no. 606862 (F-Chroma project). This research work is partly supported by the Italian MIUR-PRIN grant 2012P2HRCR on "The active Sun and its effects on Space and Earth climate" and by Space Weather Italian COmmunity (SWICO) Research Program.
18	Poster	Smooth Filament Eruption as Driver of a Geomagnetic Storm
		Palacios, J¹; Cid, C¹; Saiz, E¹; Cerrato, Y¹; Guerrero, A¹
		¹University of Alcalá (UAH
		We have investigated a filament eruption on Sept 29, 2013 associated to a CME and a moderate geomagnetic storm. This smooth filament eruption seems to be related to a flux emergence, provoking the filament instability. Data from SDO (both AIA and HMI) and LASCO have been used. In addition to the solar photospheric and low-corona analyses and CME expansion, the whole Sun-Earth chain has been studied, with an special emphasis to the geomagnetic observatories data: Dst, a local index (LDIñ) from Spain and magnetometer data from other latitudes have been compared to assess the importance of the storm.
19	Poster	The Signature of Flaring Activity in Multifractal Measurements based on SDO/HMI Observations
		Ermolli, I¹; Giorgi, F¹; Stangalini, M¹; Romano, P²; Zuccarello, F³; Criscuoli, S⁴
		¹INAF Osservatorio Astronomico di Roma; ²INAF Osservatorio Astrofisico di Catania; ³Universita` degli studi di Catania; ⁴NSO
		Recent studies indicate that measurements of multifractal parameters of active regions (ARs) are not efficient flare predictors. Attempting validation of this result on higher-resolution observations and larger datasets than employed in earlier studies, we analyzed long and high-cadence time series of line-of-sight magnetograms of forty-three flaring and flare-quiet regions observed with SDO/HMI from May 2010 to December 2013. On these data, we estimated four multifractal parameters already used in the literature, the generalized fractal dimensions D_0 and D_8, and the multifractal parameters C_div and D_div, by taking into account both the total unsigned and signed flux in the analyzed ARs. For each region, we studied the temporal evolution of the measured parameters, aiming to single out distinctive patterns that could be associated with the flaring activity of the region. In agreement with previous findings, we found that the estimated parameters are only weakly related to the flare activity on the time scale of the AR disc transit. Besides, the trends of values measured on flare-quiet and flaring ARs show unclear flare-related changes. This holds for estimates based on both total unsigned and signed flux measurements, though the time series derived from signed flux data corresponding to the trailing polarity of each AR show patterns that may be associated with the flare activity. This study has been carried out in the framework of the EU FP7 project "eHEROES Environment for Human Exploration and RObotic Experimentation in Space" (grant n. 284461).
20	Poster	New Flare Detection Algorithm And Flare List for PROBA2/LYRA
		Ryan, D¹; Dominique, M¹; Stegen, K¹; Dammasch, I¹; Katisyannis, A¹
		¹Royal Observatory of Belgium/Solar-Terrestrial Centre of Excellence
		In this poster we present a newly developed automated flare detection algorithm for LYRA (Large Yield Radiometer) onboard PROBA2. LYRA observes full-disk integrated solar irradiance from X-ray to UV in four passbands. Although PROBA2 is predominantly a technology demonstration mission, the LYRA passbands were chosen because of their relevance to space weather, solar activity, and in particular, solar flares. This new flare detection algorithm will be applied as part of the LYRA data processing pipeline at the Royal Observatory of Belgium in near-real-time and the resulting LYRA flare list will be made publicly available. The LYRA flare list will make it easier and faster to identify flares for both single- and multi-instrument studies as well as improve operational flare detection. This software will thus provide a powerful tool for the study and detection of solar flares.
22	Poster	Inferring the Global Structure of CMEs' Magnetic Field using Multi-Spacecraft Measurements
		Al-Haddad, N¹; Poedts, S¹; Farrugia, C²; Lugaz, N²; ¹KU Leuven; ²University of New Hampshire
		Evaluating the magnetic field structure of coronal mass ejections (CMEs) has always been a challenging problem. Different approaches have been carried out to estimate it, from remote sensing observations to fitting and reconstructing the magnetic field using data from observations, assuming that the structure is that of a twisted flux rope. We have shown perviously that using single spacecraft measurements yields different results on the structure of the magnetic field depending on the fitting method used. We have also demonstrated how fitting techniques and reconstruction methods misinterpret writhed magnetic field lines as twisted flux rope. Here, we use a new approach to understand the global magnetic structure of CMEs through multi-spacecraft reconstruction of the magnetic field for 2 different simulations; a simulation with writhed magnetic field structure, and a simulation with a flux rope structure. We investigate how the multi-spacecraft reconstruction results correspond to the actual structure of the events, and to one another. We also examine how could this work improve our understanding of the global structure of a CME with single spacecraft measurements.
23	Poster	Automated Detection, Characterization, and Tracking of Filaments from SDO Data
		Buchlin, E¹; Mercier, C¹; Goujon, J-B¹; Vial, J-C¹
		¹CNRS
		Thanks to the cadence and continuity of AIA and HMI observations, SDO offers unique data for detecting, characterizing, and tracking solar filaments, until their eruptions, which are often associated with coronal mass ejections. Because of the requirement of short latency when aiming at space weather applications, and because of the important data volume, only an automated detection can be worked out. We present the code "FILaments, Eruptions, and Activations detected from Space" (FILEAS) that we have developed for the automated detection and tracking of filaments. Detections are based on the analysis of AIA 30.4 nm He II images and on the magnetic polarity inversion lines derived from HMI. Following the tracking of filaments as they rotate with the Sun, filament characteristics are computed and a database of filaments parameters is built. We present the algorithms and performances of the code, and we compare its results with the filaments detected in Halpha and already present in the Heliophysics Events Knowledgebase. We finally discuss the possibility of using such a code to detect eruptions in real time.
24	Poster	Trend of the Magnetic Helicity Flux during the Formation and the Destabilization of Flux Ropes
		Zuccarello, F¹; Guglielmino, S¹; Romano, P²; Zuccarello, F³
		¹University of Catania; ²INAF - Catania Astrophysical Observatory; ³LESIA, Observatoire de Paris, CNRS, UPMC, Université Paris Diderot
		We present the results describing the trend of the magnetic helicity accumulation during the phases of formation and successive destabilization of the flux ropes in the Active Regions (ARs) NOAA 11318 and NOAA 11675, where a C1.4 GOES class flare associated with a Coronal Mass Ejection (CME) and an M1.9 GOES class flare occurred, respectively. Observing the two ARs by HMI/SDO and AIA/SDO since their appearance on the solar disc, we found a different behaviour in the accumulation of the magnetic helicity flux in corona, depending on the magnetic configuration and on the location of the flux ropes in the ARs. Our results suggest that the complexity and strength of the photospheric magnetic field is only a partial indicator of the real likeliness of an AR to produce the eruption of a flux rope and subsequent CME. This allows us to speculate that for the occurrence of CMEs associated with ARs, it is important not only the presence of a flux rope, but also the configuration of the surrounding magnetic field. This research work has received funding from the European Commissions Seventh Framework Programme under the grant agreements no. 284461 (eHEROES project), no. 312495 (SOLARNET project), no. 606862 (F-Chroma project). This research is also partly supported by the Italian MIUR-PRIN grant 2012P2HRCR on "The active Sun and its effects on Space and Earth climate" and by Space Weather Italian COmmunity (SWICO) Research Program. The contribution of F.P.Z. has been funded by the FWO Vlaanderen through the grant agreement no 1272714N (FWO Vlaanderen).
25	Poster	SoFAST: Continuously Monitoring Solar Activity as a Driver for Space Weather
		Bonte, Katrien¹; Berghmans, David¹; De Groof, Anik²; Poedts, Stefaan³; ¹Royal Observatory of Belgium; ²European Space Agency / ESAC; ³Centre for mathematical Plasma-Astrophysics
		The Solar Feature Automated Search Tool (SoFAST, Bonte et al 2013) detects dynamic events in SWAP EUV images. SWAP is a 17.4 nm EUV imager onboard ESA’s PROBA2 mission. The SoFAST algorithm is an operational tool that runs on the latest SWAP data, resulting in the real-time list of SoFAST EUV events available online (www.sidc.be/sofast). We have built the first SoFAST EUV event catalogue by running the tool over more than 3 years of SWAP data, taken during the period from April 2010 to June 2013. The catalogue provides timing, heliographic position and a customised classification as well as movies and graphs for more than 2000 EUV events. In this presentation we present results from Katrien Bonte's recently defended PhD thesis. For the validation of the SoFAST tool, we compare its output with associated events, mainly from the NOAA GOES catalogue. We describe the variety of typical dynamic EUV events detected, ranging from AR transient brightenings to large plasma eruptions. We statistically analyse the temporal and the spatial distribution of the SoFAST events during the rise of solar cycle 24. Our analysis shows that SoFAST output is well correlated with other indicators of solar activity. We investigate the utility of the tool for space weather forecasting, by addressing the following questions: Can space weather important CMEs be correlated with a SoFAST EUV event as potential low coronal signature? Do X-ray flares leave a significant signature in SWAP EUV bandwidth? Which types of events can be catalogued from intensive EUV monitoring? Is the catalogue eligible to serve as input for space weather alert systems and virtual observatories? In general, how can we use the observed dynamics in SWAP image sequences for space weather monitoring?
26	Poster	Distinct CME Evolution from the Low to the High Corona
		Pick, M
		Observatoire de Paris
		Very few Coronal Mass Ejections (CMEs) have been studied by combining EUV and radio imaging instruments sharing the same ﬁeld of view. This is, however, a decisive advantage: it allows to investigate precisely i) the formation of a CME, how successive interactions with the ambient medium influence its evolution and trajectory; ii) the formation and evolution of shocks (type II bursts) during the same event. To illustrate these comments, we present a few CMEs which were observed jointly in EUV by the Solar Dynamic Observatory (SDO/AIA) and STEREO, in radio by the Nançay Radio-Heliograph (NRH) coupled with radio spectrographs. We focus essentially on two distinct CME events, both associated with the formation of a shock; for the first one, the formation of a flux rope is identified in EUV and radio, not for the second one. We compare their progression successively in EUV, radio and finally in white light.
27	Poster	A Two-Fluid Computational Model to Study Magnetic Reconnection in Reactive Plasmas Under Low Chromospheric Conditions
		Alvarez Laguna, A¹; Lani, A¹; Poedts, S²; Mansour, N N³; Kosovichev, A⁴
		¹von Karman Institute for Fluid Dynamics; ²KU Leuven; ³NASA Ames Research Center; ⁴Big Bear Solar Observatory
		Magnetic reconnection is a physical process enabling for the conversion of so-called free (non-potential) magnetic energy into kinetic and thermal energy by breaking the flux conservation law that exists for ideal (i.e. perfectly conducting) plasmas. This ubiquitous phenomenon in magnetized plasma plays an important role in the Space Weather context. It is found in the solar atmosphere expanding into the solar wind, the interstellar medium, (extra-) galactic disks and planetary magnetospheres. It is a key process in many transient plasma phenomena found in the Sun such as solar flares, coronal mass ejections, magnetospheric substorms and the polar lights. Most of the available literature on magnetic reconnection has focused on resistive single-fluid magnetohydrodynamics. More recently, multi-fluid models are being used in modeling the earth magnetospheric plasma and laboratory experiments. However, very little investigations have been devoted to collisional and reacting weakly ionized plasma, that include the effects of neutrals. These effects are crucial when modeling partially ionized solar chromospheric conditions and very weakly ionized photospheric conditions. In this work, we present a computational model that simulates magnetic reconnection under low chromospheric conditions using a two-fluid (plasma + neutrals) approach introduced by Leake et al. (2012) in the context of space weather and two representations of the magnetic field. The first representation considers the full Maxwell equations complemented with a hyperbolic divergence cleaning method to insure enforcing numerically the divergence constrains on the electric and magnetic fields. The second model neglects the displacement current, and solves the induction equation. The latter approximation is used to simulate magnetic 3-D reconnection in conditions representative of the chromosphere. These developments are implemented into a Finite Volume solver integrated in the COOLFluiD platform. We compare our numerical results with those found in the literature.