Session - Progresses and challenges in coupling models for predicting space weather from the Sun to the Earth

N. Ganushkina, S. Poedts, A. Hilgers, D. Pitchford, B. van der Holst, P. Wintoft

Most space weather tools are limited to forecasting solar wind parameters at L1 and are too inaccurate to predict some important parameters (e.g. the AE index). To overcome this, tools based on coupled first-principle physics models should be developed that include the whole chain of processes starting on the Sun and ending at the Earth's surface. The ongoing EU and ESA SSA funding schemes focused on space weather related research are stimulating the development of numerous, more reliable tools aimed at forecast solar events, modeling the propagation of solar energetic particles and the response of the Earth's radiation belts, GICs, etc. This session focuses on recent advances and remaining challenges in coupled space-weather models, primarily, but not exclusively, in Europe. This session is soliciting contributions/reports on experiences, pitfalls, good practices, supporting software frameworks, etcetera for coupling two or more models to each other. Hereby, 'model' is to be interpreted in a broad way and includes e.g. also data sources, visualization software tools, etc. This topic thus also includes methods like Kalman filtering and data assimilation to tackle the challenge of infusing data in models in a proper way. Much can be learnt on these topics from research groups that have a broad experience, not only in our field, but also in meteorology. Papers are solicited on topics including existing models, physical description, numerical modelling, data processing, stakeholders needs and requirements, and validation.

Talks
Wednesday November 25, 11:00 - 13:00, Mercator

Poster Viewing
Wednesday November 25, 10:00 - 11:00, Poster area

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Talks : Time schedule

Wednesday November 25, 11:00 - 13:00, Mercator

11:00	Towards Forecasting Capabilities from the Sun Down to Earth	Kuznetsova, M et al.	Invited Oral
	M. Kuznetsova, P. Macneice, M. Maddox, L. Mays, A. Pulkkinen, L. Rastaetter, J-S. Shim, A. Taktakishvili, C. Wiegand, Y. Zheng
	Community Coordinated Modeling Center, NASA Goddard space Flight Center
	The Community Coordinated Modeling Center (CCMC, http://ccmc.gsfc.nasa.gov) hosts an expanding collection of state-of-the-art space weather models, coupled model chains and modeling frameworks that cover the entire domain from the solar corona to the Earth’s upper atmosphere. The presentation will focus on successes and challenges in model coupling and predictive end-to-end modeling and forecasting approaches.
11:15	Towards precise global space weather forecasts: MHD and hybrid-Vlasov simulations compared	Palmroth, M et al.	Invited Oral
	Palmroth, M.[1], von Alfthan, S.[1], Sandroos, A.[1], Kempf, Y.[1,2], Hoilijoki, S.[1,2], van de Kamp, M.[1], Honkonen, I.[3], and Janhunen, P.[1]
	[1] Finnish Meteorological Institute, Helsinki, Finland; [2] University of Helsinki, Helsinki, Finland; [3] NASA/Goddard Space Flight Center, USA
	While global computer simulations are key in modern space research as a context to in situ data, they are also being targeted as forecasting tools for space weather purposes. Nowcasting and forecasting space weather with a global computer simulation requires that the code is fast enough to process solar wind observations and predict the solution in a simulation volume covering the solar wind, magnetosphere and ionosphere. Due to the large size of the system, the earliest global simulations utilised the magnetohydrodynamic (MHD) approach. With today’s computing power and efficient high performance computing methods, the global MHD simulations can already be executed in real-time. However, as MHD assumes that plasma is fluid having a single temperature, spatially overlapping multi-temperature plasmas especially in the inner magnetosphere where most spacecraft reside has posed a problem to MHD simulations, compromising the forecast accuracy. There are two possibilities to overcome this problem, either couple a dedicated inner magnetospheric simulation to the MHD code, or in place of MHD, use the plasma kinetic theory that can accurately describe multi-temperature plasmas. So far the latter approach has been mostly neglected worldwide due to the intensive computations involved. This presentation introduces two global simulations developed at the Finnish Meteorological Institute. The first part discusses Grand Unified Magnetosphere Ionosphere Coupling Simulation, version 5 (GUMICS-5). We will briefly overview the GUMICS-5 modelling capabilities including real-time test simulations. Second, we discuss FMI’s new flagship simulation Vlasiator, which is the world’s first global hybrid-Vlasov simulation solving ions with plasma kinetic theory, while electrons are a charge-neutralising fluid. Vlasiator includes ion kinetic effects such as e.g., the foreshock waves, magnetosheath turbulence and waves, and most importantly, the inner magnetospheric ion physics in unprecedented detail. Due to the massive amount of computations in Vlasiator, the code is presently not targeted for real-time calculations. However, with GUMICS-5’s real-time capabilities and Vlasiator’s unprecedented accuracy, precise global space weather forecasts are one step closer.
11:30	Estimating the Global Solar Photospheric Magnetic Field Distribution Using the ADAPT Model	Arge, C et al.	Invited Oral
	Charles Arge[1], Carl J. Henney[1], Kyle Hickmann[2], Humberto C. Godinez[2], Kathleen Shurkin[3]
	[1] Air Force Research Laboratory; [2] Los Alamos National Laboratory; [3] Boston College
	As the primary input to nearly all coronal models, reliable estimates of the global solar photospheric magnetic field distribution are critical for accurate modeling and understanding of solar and heliospheric magnetic fields. Over the last several years AFRL, in collaboration with Los Alamos National Laboratory (LANL) and the National Solar Observatory (NSO), has been developing a model that produces much more realistic estimates of the instantaneous global photospheric magnetic field distribution than that provided by traditional photospheric field synoptic maps. The Air Force Data Assimilative Photospheric flux Transport (ADAPT) model is a photospheric flux transport model, originally developed at NSO, that makes use of data assimilation methodologies developed at LANL. The flux transport model evolves the observed solar magnetic flux using relatively well understood transport processes when measurements are not available and then updates the modeled flux with new observations (available from both the Earth and the far side of the Sun) using data assimilation methods that rigorously take into account model and observational uncertainties. This talk provides an overview of the ADAPT model followed by several examples of how it is being used to improve coronal and solar wind modeling as well as space weather forecasts.
11:45	Forecasting Space Weather at the NOAA Space Weather Prediction Center	Onsager, T et al.	Invited Oral
	Terrance G. Onsager[1], Howard J. Singer[1], George Millward[1,2], Christopher Balch[1], Tom Berger[1], Gabor Toth[3], Daniel Welling[3], Tamas Gombosi[3]
	[1] NOAA Space Weather Prediction Center; [2] University of Colorado, Cooperative Institute for Research in Environmental Sciences (CIRES); [3] University of Michigan, Atmospheric, Oceanic and Space Sciences
	In the United States, the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center (SWPC) is responsible for providing space weather products and services that meet the evolving needs of the Nation. The demand for these services and space weather forecasts has increased over time as we become a more technologically dependent society. Furthermore, the provision of space weather services has received increased attention from the highest levels of government and as a global response to solar disturbances and internal forcing, space weather forecasting benefits from international collaborations with models and observations. In this presentation, we will provide an overview of space weather forecasting capabilities provided by SWPC today, current activities and lessons learned that are related to transitioning physics-based models into operations, and challenges for improving future forecasting capabilities. There will be an emphasis on the geospace environment and radiation belts as well as examples of forecasting capabilities using the geospace components of the University of Michigan’s Space Weather Modeling Framework that is transitioning from research to operations.
12:00	Coupling Continuum and Particle space weather tools via the implicit moment method: the IMM approach	Lapenta, G et al.	Oral
	Giovanni Lapenta, Swiff team
	EC project
	Coupling different space weather tools is a task involving logistics, legal issues, units conversion, software practices, hardware, commercial interests. But at the center of the issue stands a fundamental mathematical problem. The same problem that put Ancient Greek philosophers against and another, or put Mach against Boltzmann. Is matter a continuum or a discrete set of particles? Of course we now know that the crystal clear answer is: it depends. It depends on the scales. When tracking a CME from the dollar corona to earth and beyond, the tool of choice is ENLIL or a competitor method based on a MHD continuum description where the interstellar plasma and magnetic fields are treated as a (magneto)fluid. When looking at energetic particle acceleration at a shock, the plasma needs to be treated as a collective of interacting particles. The same duality of description holds for many other examples. In general as the scales become smaller (reconnection regions, shocks, wave heating processes) the particle view must take over. The method to describe matter as particles in called kinetic theory and was developed by Boltzmann who derived the equation beating his name. The method to describe matter as a continuum is called fluid. The might clash between Boltzmann and Mach speaks for the complexity of connecting the two approaches. The problem at the core is not only the different language spoken by the two methods but by the existence in the kinetic approach of many more characteristic speed for signal transmission than in the fluid method. The fluid method will not know what to do with the extra channels received and will not know what to communicate to the kinetic methods for the signals it lacks. Even on the channels they have in common the information is not travelling in the same way. In the kinetic case, the waves of fluid models have a different speed and acquire a different nature. We report here the new developments of the Swiff (www.swiff.eu) project, a recently completed EC-funded space weather project, continued now under the CHARM belgian project. Our approach to link fluid with kinetic is to use the implicit moment method (IMM) [1]. Moments are the mathematical tools to reduce (via phase space integrals) the kinetic description to the fluid description. We present an integrated approach where fluid and kinetic models are allowed to communicate thanks the IMM filter. [1] Lapenta, G. "Particle simulations of space weather." J. Computat. Phys. 231.3 (2012): 795-821.
12:15	PROGRESS - Prediction of Geospace Radiation Environment and Solar Wind Parameters	Balikhin, M et al.	Oral
	M. A. Balikhin[1], S. N. Walker[1], R. Erdelyi[1], N. Ganushkina[2], I. Sillanpaa[2], S. Dubyagin[2], B. van der Holst[3], M. Liemohn[3], V. Krasnoselskikh[4], V. Shastun[4], Y. Shprits[5], T. Arber[6], K. Bennett[6], P. Wintoft[7], M. Wik[7], V. Yatsenko[8]
	[1] University of Sheffield, Sheffield, U.K.; [2] Finnish Meteorological Institute, Helsinki, Finland; [3] University of Michigan, Ann Arbor, USA; [4] CNRS-LPC2E, Orleans, France; [5] UCLA, and MIT, U.S.A.; [6] University of Warwick, Coventry, U.K.; [7] Swedish Institute for Space Physics, Lund, Sweden; [8] Space Research Institute, Kiev, Ukraine
	PROGRESS is an EU funded project to develop an accurate and reliable forecast system for space radiation. The main tasks of the project fall into 3 areas, namely 1) The forecast of the state of the solar wind at L1 together with the propagation of potential space weather hazards, 2) Forecast of the evolution of geomagnetic indices such as Dst, Kp, and AE which are used as inputs to numerical models to quantify the geomagnetic state of the magnetosphere, and 3) the forecast of the radiation environment of the inner magnetosphere, with particular attention to the high and low electron fluxes that may have detrimental effects to satellites in geosynchronous and medium Earth orbit. This presentation provides an introduction to the project and discusses some of the early results.
12:30	Data Assimilative Real Time Prediction of the Earth Radiation Belts	Shprits, Y et al.	Oral
	Yuri Shprits[1,2], Adam Kellerman[1], Alexnder Drozdov[1], Tatiana Podladchikova[1]
	[1] ULCA; [2] MIT
	We present real time simulations of the coupled GREEP code for the prediction of GEO fluxes of relativistic electrons and VERB-3D code with data assimilation. The empirical GREEP code is driven by the solar wind measurements and statistical distributions of flues and time-lagged solar wind density and velocity. The VERB diffusion code is assimilating real time data from GOES and Van Allen Probes. The data assimilative combined codes can provide now-casting and feasting of the global state of the radiation belt fluxes at all energies and pitch angles. This information can be used to compute real-time fluencies on satellites at different orbits.
12:45	Turbulent energization of protons and minor ions by oblique wave spectra near the Earth	Maneva, Y et al.	Oral
	Yana Maneva[1], Stefaan Poedts[1], Adolfo Vinas[2] and Pablo Moya[2]
	[1] CmPA at KU Leuven, Leuven, Belgium; [2] NASA Goddard Space Flight Center, Heliophysics Science Division, Geospace Physics Laboratory, Greenbelt, MD, USA
	Turbulent waves and structures are ubiquitous and indispensable part of the solar wind throughout the Heliosphere and have crucial contribution to the energetization of particles in the high beta plasma near the Earth, especially in regions where strong wave activity is present. Wave-based turbulent energization of protons and minor ions in the undisturbed solar wind can occur through resonant and non-resonant wave-particle interactions, related to wave absorption, particle scattering and diffusion in phase space. In this paper we focus on wave-based mechanism for non-resonant heating of protons and alpha particles in the solar wind close to the Earth. We perform 2.5D hybrid simulations with fluid electrons and kinetic ions to study the effects of oblique wave propagation for the minor ion energization by initial broad-band spectra, consisting of left-hand polarized forward propagating Alfven waves with a Kolmogorov-type spectral slope. The numerical model is driven by observations of the solar wind plasma parameters at 1AU and takes into account the differential streaming between the protons and the minor ions. For the chosen spectral range of the external initial wave source we observe preferential perpendicular heating for the minor ions, together with generation of temperature anisotropies from the initial isotropic velocity distributions for both ion species. The preferential perpendicular heating for the minor ions is present for all initial angles of propagation and is strongest for the case of highly-oblique wave spectra, which also involves strong parallel heating for both species. As no high-frequency proton-cyclotron waves are initially considered, nor generated the protons experience perpendicular cooling at all propagation angles.

Posters

Wednesday November 25, 10:00 - 11:00, Poster area

1	Models for predicting of magnetospheric VLF response to atmospheric perturbations impact	Bespalov, P et al.	p-Poster
	Peter A. Bespalov[1] and Olga N. Savina[2]
	[1] Institute of Applied Physics, Nizhny Novgorod, Russia; [2] National Research University Higher School of Economics, Nizhny Novgorod, Russia
	In this report, we focus on the possible influence of atmospheric acoustic-gravity waves on magnetospheric processes. We will examine in more detail the modulation of the reflection coefficient of electromagnetic VLF waves from the ionosphere. The reflection coefficient of whistler waves from the ionosphere is determined by several factors, which can be stimulated by acoustic-gravity waves: electron density in the ionosphere, electronic density gradient, and small-scale instabilities. The reflection coefficient from the ionosphere will determine the magnetospheric resonator quality for VLF waves. The magnetosphere forms a plasma magnetospheric maser in the region of the electron radiation belts. This system is very sensitive even to small modulations of the magnetospheric resonator quality (Q-factor). We will try to explain this by the calculations. The plasma magnetospheric maser is especially sensitive to external periodic actions at frequencies close to its natural frequency. The parameters of the system can produce slowly-decaying oscillations representing alternating stages of accumulation of energetic electrons and their precipitation into the ionosphere during pulses of electromagnetic radiation. Bespalov, P.A., Savina, O.N. Earth Planets Space, v.64, p.451–458, 2012.
2	Modeling evolution of the ion charge state composition of solar wind in the low corona	Goryaev, F et al.	p-Poster
	Farid Goryaev[1], Vladimir Slemzin[2], Yulia Shugay[3], Denis Rodkin[4], Igor Veselovsky[5]
	[1] P.N. Lebedev Physical Institute of the RAS; [2] P.N. Lebedev Physical Institute of the RAS; [3] Skobeltsyn Research Institute of Nuclear Physics, Moscow State University; [4]  P.N. Lebedev Physical Institute of the RAS; [5] Skobeltsyn Research Institute of Nuclear Physics, Moscow State University
	The main factors that determine the geo-effectiveness of solar wind (SW) flows are magnitude and duration of the southward component of interplanetary magnetic field, Bs. Unfortunately, at present the parameter Bs cannot be reliably predicted in advance, due to lack of appropriate methods of identification of coronal sources, as well as due to the unknown evolution of magnetic structure of the SW plasma during its passage throughout the heliosphere. The coronal structures responsible for production of geo-effective SW flows can be unambiguously identified using the ion charge composition of solar wind measured in situ, because it freezes within a few solar radii from the solar surface. However, the ion charge composition evolves as plasma travels through the corona from the source to the freeze-in region due to ionization and recombination of plasma expanding at a given solar activity level. For quasi-stationary flows from CHs evolution of the SW ion charge state was studied by Landi et al. (2012). For CME-related SW plasma, a number of sophisticated multi-fluid MHD models have been developed recently (e.g. Ofman et al. 2011, 2013), but these models are still not able to simulate the whole ensemble of the ion composition parameters of the transient SW flows measured in situ. We describe a model for calculating the ion charge state of the CME-produced SW in the inner corona using combination of two methods: (i) calculation of plasma density, temperature and magnetic field distributions during expansion of flaring plasma in the corona by applying the standard numerical MHD model; and (ii) simulation of evolution of the SW ion charge state in the inner corona using spectroscopic methods under appropriate equilibrium and environmental conditions. The results of test simulations of the O and Fe ions states for the flare-related plasma at solar minimum and maximum are presented. This work is implemented in the frames of the ISEST/Minimax24 campaign.
3	First global 3D two-way coupled MHD-EPIC simulation of a magnetosphere: Ganymede	Markidis, S et al.	p-Poster
	S. Markidis[1], G. Toth[2], L.K.S. Daldorff[2], X. Jia[2], Y. Chen[2], T. Gombosi[2], A. Glocer[3]
	[1] KTH Royal Institute of Technology; [2] University of Michigan; [3] NASA Goddard
	We present the first 3D global simulation of Ganymede’s magnetosphere in a unified framework coupling the fluid and kinetic models. An MHD model describes the global interaction of solar wind with Ganymede’s magnetosphere over the whole simulation domain. A kinetic model is used only in the selected space regions, where kinetic effects dominate and MHD description fails. In particular, kinetic regions are used in Ganymede magnetotail and dayside magnetopause to correctly describe magnetic reconnection in these regions. This is the first simulation capable of combining fluid and kinetic approaches in a realistic large-scale simulation of a planet’s magnetosphere. In this work, the BATS-R-US MHD code is coupled with the iPIC3D Particle-in-Cell kinetic code. The coupling is two-way as both the MHD and kinetic codes provide reciprocal feedback. The electromagnetic fields of the fluid region are used as the boundary conditions for the electromagnetic fields in the kinetic regions; the fluid pressure tensor is used to sample distribution functions at the boundary of the kinetic regions. On the other hand, the kinetic areas provide the fluid regions the correct electromagnetic field values calculated with the kinetic approach. The coupling of the two codes has been realized within the SWMF framework, a highly scalable parallel environment for space weather modeling. The software coupling is achieved by using message passing among different BATS-R-US and iPIC3D instances that can run on different computational resources. In this talk, we present the coupling strategy that enabled the first global fluid-kinetic simulation of Ganymede’s magnetosphere and the simulation results of the solar wind interaction with Ganymede’s magnetosphere focusing on the kinetic magnetic reconnection in magnetotail and in dayside magnetopause. Finally, we discuss the impact and application of this work to other planetary magnetospheres.
4	Estimating the inner heliosphere solar wind flow structure from the Heliospheric Imager observations.	Barnard, L et al.	p-Poster
	Luke Barnard, Chris Scott, Mat Owens, Mike Lockwood
	University of Reading
	The Heliospheric Imager (HI) instruments, aboard the twin STEREO spacecraft, are white-light cameras that image plasma density structures in the solar wind. These imagers have been used to great effect in studying large-scale transient structures propagating through the inner heliosphere, such as coronal mass ejections and co-rotating interaction regions. However, the HI data also contains information on the structure of the continuous background solar wind flow. This is a potentially valuable data source that could be used to further constrain the Sunward boundary conditions of numerical models of the solar wind, such as ENLIL. For example, ENLIL requires as input the state of the solar wind at the Sunward boundary, including the solar wind flow speed, mass density and magnetic field vector. Typically this information is derived from the output of other models, such as the Wang-Sheeley-Arge model, ultimately being driven by synoptic maps of the observed Photospheric magnetic field. The HI data may provide an independent estimate of the solar wind flow structure at this Sunward boundary and so may be used to improve the accuracy of the ENLIL inner boundary conditions. We present the results of our investigations into deriving the solar wind flow structure from the HI images and present a comparison of how these estimates differ from those obtained from the Wang-Sheeley-Arge model. Furthermore, we discuss our preliminary results from investigating how the HI-derived solar wind structure may be best utilised to improve the accuracy of the Sunward boundary conditions used with ENLIL.
5	Predicting the solar wind speed from the surface of the Sun up to the heliosphere	Pinto, R et al.	p-Poster
	Rui Pinto, Alexis Rouillard
	IRAP - Research Institute in Astrophysics and Planetology, Toulouse
	We present a new solar wind model which takes a coronal magnetic field map as input, and computes a collection of solar wind profiles spanning a region of interest of the solar atmosphere (up to a full synoptic map) at any instant desired. This tool aims at producing robust predictions of the fast and slow wind speed profiles, plasma density, temperature, sound and alfvén speeds from 1 to 30-50 solar radii (and at all latitudes and longitudes) in order to constraint the trajectories and delays of propagation of disturbances occurring at the surface of the Sun or in the corona. The outputs of this model can provide a complete set of boundary conditions for heliospheric propagation models (such as ENLIL), hence outperforming the standard procedure based on WSA wind speed estimates. The method was designed to be quick (quicker than global MHD simulations) yet keeping a good description the plasma heating and cooling mechanisms (coronal heating, conductive and radiative cooling). The background coronal magnetic field is, currently, determined via surface magnetograms and PFSS extrapolations, but is ready to include constraints from data assimilation techniques as these become available. This tool is currently being tested and calibrated using coronal and heliospheric CME data, and will be included in the CDPP/STORMS service in the near future. We will also discuss the cyclic variations of the fast and slow wind flow distributions based on numerical simulations of the solar dynamo (capable of assimilating surface magnetic field time-series), the corona and solar wind covering an 11 yr activity cycle. The wind speeds we obtained are in agreement with in-situ measurements (ULYSSES) and radio maps (IPS). This is work is supported by the FP7 project #606692 (HELCATS).
6	The LANL SHIELDS Project	Jordanova, V et al.	p-Poster
	V.K. Jordanova[1], G.L. Delzanno[2], M.G. Henderson[1], H.C. Godinez[2], C.A. Jeffery[1], E.C. Lawrence[3], J.D. Moulton[2], L.J. Vernon[3], J.R. Woodroffe[1], Y. Yu[2], L. Zhao[2], G. Tóth[4], D.T. Welling[4], M.F. Thomsen[1], J. Birn[1], J.E. Borovsky[1,4], C. Lemon[5], J.M. Albert[6], S.L. Young[6], R.B. Horne[7], S. Markidis[8]
	[1] Intelligence and Space Research, Los Alamos National Laboratory, Los Alamos, New Mexico, USA; [2] Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA; [3] Computer, Computational, and Statistical Sciences, Los Alamos National Laboratory, Los Alamos, NM, USA; [4] Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan, USA; [5] The Aerospace Corporation, El Segundo, California, USA; [6] Air Force Research Laboratory, Kirtland AFB, New Mexico, USA; [7] British Antarctic Survey, NERC, Cambridge, England; [8] PDC Centre, KTH Royal Institute of Technology, Stockholm, Sweden
	The near-Earth space environment is a highly dynamic and coupled system through a complex set of physical processes over a large range of scales, which responds nonlinearly to driving by the time-varying solar wind. Predicting variations in this environment that can affect technologies in space and on Earth, i.e. “space weather”, remains a big space physics challenge. We present a recently funded project through the Los Alamos National Laboratory (LANL) Directed Research and Development (LDRD) program that is developing a new capability to understand, model, and predict Space Hazards Induced near Earth by Large Dynamic Storms, the SHIELDS framework. The project goals are to specify the dynamics of the hot (keV) particles (the seed population for the radiation belts) on both macro- and micro-scale, including important physics of rapid particle injection and acceleration associated with magnetospheric storms/substorms and plasma waves. This challenging problem is addressed using a team of world-class experts in the fields of space science and computational plasma physics and state-of-the-art models and computational facilities. New data assimilation techniques employing data from LANL instruments on the Van Allen Probes and geosynchronous satellites are developed in addition to physics-based models. This research will provide a framework for understanding of key radiation belt drivers that may accelerate particles to relativistic energies and lead to spacecraft damage and failure. The ability to reliably distinguish between various modes of failure is critically important in anomaly resolution and forensics. SHIELDS will enhance our capability to accurately specify and predict the near-Earth space environment where operational satellites reside.
7	Multi-fluid modeling of magnetic reconnection in the Sun atmosphere	Alvarez laguna, A et al.	e-Poster
	Alejandro Alvarez Laguna[1,2], Andrea Lani[1], Stefaan Poedts[2], Herman Deconinck[1]
	[1] von Karman Institute for Fluid Dynamics; [2] KU Leuven
	Magnetic reconnection can be considered as one of the most challenging unresolved problems in laboratory and astrophysical plasma. It occurs when two magnetic fields lines of different polarity are pulled together by plasma motions. A completely new magnetic configuration is formed by breaking and rejoining the field lines, resulting in a conversion of magnetic energy into thermal energy and flow velocity of the plasma. Magnetic reconnection is present in most of the unsteady and eruptive phenomena in the Sun atmosphere, including Coronal Mass Ejections (CMEs) and solar flares. Also, it occurs in the chromosphere, bringing about chromospheric jets and spicules, being considered a likely mechanism to heat the corona to a few million degrees in the so-called transition region. In this work, we present a computational model that simulates magnetic reconnection in the Sun atmosphere using a three-fluid (electrons + ions + neutrals). This model considers non-equilibrium partial ionization effects including ionization, recombination reactions and scattering collisions while simulating the interplay between the charged particles with the electromagnetic field. Previous two-fluid simulations showed that the dynamics of ions and neutrals are decoupled during the reconnection process. Also, the effect of the chemical non-equilibrium in the reconnection region plays a crucial role, yielding faster reconnection rates. We extended these simulations with a three-fluid model that considers separately the dynamics of electrons. This new model provides a better description of the complex dynamics taking place during the reconnection, both in Sweet-Parker reconnections and during the tearing instability. The results are compared with the two-dimensional simulations.
8	On the long-period oscillations of the active region patterns: Method of least-square mapping on second order curves	Dumbadze, G et al.	p-Poster
	G. Dumbadze, B.M. Shergelashvili, V. Kukhianidze, G. Ramishvili, T.V. Zaqarashvili, M. Khodachenko, E. Gurgenashvili, S. Poedts and P. De Causmaecker
	Ilia State University and KU Leuven
	Active Regions (ARs) are major sources of a variety of solar dynamic events. The development of automated detection and identification tools for solar features is required for a deeper understanding of the solar cycle. We studied the oscillatory dynamics of two ARs: NOAA 11327 and NOAA 11726, using two different methods of pattern recognition. In this work we developed a novel method of automated AR border detection and used another existing method for the proof-of-the-concept. The first method is using least square fitting on the smallest ellipse enclosing the AR and the second method applies regression on the convex hull. After processing the data we found that the axes and the inclination angle of both the ellipse and the convex hull oscillate in time. These oscillations are interpreted as the second harmonic of the standing long-period kink oscillations (with the node at the apex) of the magnetic flux tube connecting the two main sunspots of the ARs. We also found that the inclination angles oscillate with the characteristic periods 4.9 hours in AR 11726 and 4.6 hours in AR 11327, respectively. In addition, we discovered that the lengths of the pattern axes in the ARs oscillate with similar characteristic periods and these oscillations are ascribed to standing global flute modes. In both ARs we have estimated the distribution of the phase speed magnitude along the magnetic tubes (along the two main spots) by interpreting the obtained oscillation of the inclination angle as the standing second harmonic kink mode. After comparison of the obtained results for fast and slow kink modes, we concluded that both of these modes are good candidates to explain the observed oscillations of the AR inclination angles, as in the high plasma _ regime the phase speeds of these modes are comparable and of the order of the Alfv´en speed. Based on the properties of the observed oscillations, we detected the appropriate depth of the sunspot patterns, which are in good agreement with existing helioseismic estimations of this depth. The latter analysis can be used as a base for the development of a magneto-seismological tool for ARs.