A5004960119- Solar and Space Plasma Dynamics
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Ionosphere and magnetosphere dynamics
- Solar Radiation and Photovoltaics
- Geophysics and Gravity Measurements
- Market Dynamics and Volatility
- Advanced Numerical Methods in Computational Mathematics
- Global Energy and Sustainability Research
- Oil, Gas, and Environmental Issues
- Numerical methods in engineering
- Spacecraft Design and Technology
- Gamma-ray bursts and supernovae
- Earthquake Detection and Analysis
- Complex Systems and Time Series Analysis
- Advanced Mathematical Identities
- Theoretical and Computational Physics
- Advanced Combinatorial Mathematics
- Big Data Technologies and Applications
- Advanced Mathematical Modeling in Engineering
- Forecasting Techniques and Applications
- Astrophysics and Cosmic Phenomena
- Electromagnetic Simulation and Numerical Methods
- Energy Load and Power Forecasting
Johns Hopkins University Applied Physics Laboratory
2001-2025
FORTH Institute of Applied and Computational Mathematics
2025
Academy of Athens
2015-2024
Georgia State University
2019-2022
National Technical University of Athens
2018-2019
University of Leicester
2007-2019
Foundation for Research and Technology Hellas
2019
Observatoire de Paris
2004
Laboratoire d’études spatiales et d’instrumentation en astrophysique
2004
Johns Hopkins University
2003
Shortly after the seminal paper {\sl "Self-Organized Criticality: An explanation of 1/f noise"} by Bak, Tang, and Wiesenfeld (1987), idea has been applied to solar physics, in "Avalanches Distribution Solar Flares"} Lu Hamilton (1991). In following years, an inspiring cross-fertilization from complexity theory astrophysics took place, where SOC concept was initially flares, stellar magnetospheric substorms, later extended radiation belt, heliosphere, lunar craters, asteroid Saturn ring,...
During its 2000 January flight, the Flare Genesis Experiment observed gradual emergence of a bipolar active region, by recording series high-resolution photospheric vector magnetograms and images in blue wing Hα line. Previous analyses these data revealed occurrence many small-scale, transient brightenings identified as Ellerman bombs (EBs). They occur during flux emergence, them are located near moving magnetic dipoles which field is nearly tangential to photosphere. A linear force-free...
We investigate the statistical properties of Ellerman bombs in dynamic emerging flux region NOAA Active Region 8844, underneath an expanding arch filament system. High-resolution chromospheric Hα filtergrams (spatial resolution 08), as well photospheric vector magnetograms 05) and Dopplergrams, have been acquired by balloon-borne Flare Genesis Experiment. observations reveal first "seeing-free" data set on one largest samples these events. find that occur recur preferential locations low...
We define the effective connected magnetic field, Beff, a single metric of flaring potential in solar active regions. calculated Beff for 298 regions (93 X- and M-flaring, 205 nonflaring) as recorded by SOHO/MDI during 10 yr period covering much cycle 23. find that is robust criterion distinguishing from nonflaring A well-defined 12 hr conditional probability major flares depends solely on Beff. This exceeds 0.95 M-class X-class if > 1600 G 2100 G, respectively, while maximum Beff-values are...
A new catalogue of 314 solar energetic particle (SEP) events extending over a large time span from 1984 to 2013 has been compiled. The properties as well the associations these SEP with their parent sources have thoroughly examined. include proton peak integral flux and fluence for energies above 10, 30, 60 100 MeV. associated were parametrized by flare (SF) coronal mass ejection (CME) characteristics, related radio emissions. In particular, SFs: soft X-ray (SXR) flux, SXR fluence,...
In Fall 2008 NASA selected a large international consortium to produce comprehensive automated feature-recognition system for the Solar Dynamics Observatory (SDO). The SDO data that we consider are all of Atmospheric Imaging Assembly (AIA) images plus surface magnetic-field from Helioseismic and Magnetic Imager (HMI). We robust, very efficient, professionally coded software modules can keep up with stream detect, trace, analyze numerous phenomena, including flares, sigmoids, filaments,...
Solar flares produce radiation which can have an almost immediate effect on the near-Earth environment, making it crucial to forecast in order mitigate their negative effects. The number of published approaches flare forecasting using photospheric magnetic field observations has proliferated, with varying claims about how well each works. Because different analysis techniques and data sets used, is essentially impossible compare results from literature. This problem exacerbated by low event...
Abstract We introduce and make openly accessible a comprehensive, multivariate time series (MVTS) dataset extracted from solar photospheric vector magnetograms in Spaceweather HMI Active Region Patch (SHARP) series. Our also includes cross-checked NOAA flare catalog that immediately facilitates prediction efforts. discuss methods used for data collection, cleaning pre-processing of the active region data, we further describe novel integration sampling methodology. covers 4,098 MVTS...
Solar Orbiter is the first space mission observing solar plasma both in situ and remotely, from a close distance, out of ecliptic. The ultimate goal to understand how Sun produces controls heliosphere, filling System driving planetary environments. With six remote-sensing four in-situ instrument suites, coordination planning operations are essential address following top-level science questions: (1) What drives wind where does coronal magnetic field originate? (2) How do transients drive...
Solar Energetic Particle (SEP) events are interesting from a scientific perspective as they the product of broad set physical processes corona out through extent heliosphere, and provide insight into particle acceleration transport that widely applicable in astrophysics. From operations perspective, SEP pose radiation hazard for aviation, electronics space, human space exploration, particular missions outside Earth's protective magnetosphere including to Moon Mars. Thus, it is critical...
Abstract We present a case study of solar flare forecasting by means metadata feature time series, treating it as prominent class-imbalance and temporally coherent problem. Taking full advantage pre-flare series in active regions is made possible via the Space Weather Analytics for Solar Flares (SWAN-SF) benchmark data set, partitioned collection multivariate region properties comprising 4075 spanning over 9 yr Dynamics Observatory period operations. showcase general concept temporal...
Abstract Magnetic free energy powers solar flares and coronal mass ejections, the buildup of magnetic helicity might play a role in development unstable structures that subsequently erupt. To better understand roles large eruptions, we have characterized evolution associated with 21 X-class from 2010 to 2017. Our sample includes both confined eruptive events, 6 15 each category, respectively. Using Helioseismic Imager vector field observations several hours before after event, employ (a)...
Aiming to assess the progress and current challenges on formidable problem of prediction solar energetic events since COSPAR/ International Living With a Star (ILWS) Roadmap paper Schrijver et al. (2015), we attempt an overview status global research efforts. By refer flares, coronal mass ejections (CMEs), particle (SEP) events. The emphasis, therefore, is methods flares eruptions, as well their associated SEP manifestations. This work complements COSPAR Space Weather Action Teams (ISWAT)...
Virtually all X-class flares produce a coronal mass ejection (CME), and each CME carries magnetic helicity into the heliosphere. Using magnetograms from Michelson Doppler Imager on Solar Heliospheric Observatory, we surveyed injection 48 X-flare-producing active regions recorded by MDI between 1996 July 2005 July. Magnetic flux was calculated according to method of Chae for X-flaring 345 non-X-flaring regions. Our survey revealed that necessary condition occurrence an X-flare is peak has...
Recently, several methods that measure the velocity of magnetized plasma from time series photospheric vector magnetograms have been developed. Velocity fields derived using such techniques can be used both to determine fluxes magnetic energy and helicity into corona, which important consequences for understanding solar flares, coronal mass ejections, dynamo, drive time-dependent numerical models fields. To date, these not rigorously tested against realistic, simulated data sets, in field...
ABSTRACT During the interval 2012 March 7–11 geospace experienced a barrage of intense space weather phenomena including second largest geomagnetic storm solar cycle 24 so far. Significant ultra-low-frequency wave enhancements and relativistic-electron dropouts in radiation belts, as well strong energetic-electron injection events magnetosphere were observed. These ultimately associated with two ultra-fast (>2000 km s −1 ) coronal mass ejections (CMEs), linked to X-class flares launched...
Context. The Solar Orbiter spacecraft will be equipped with a wide range of remote-sensing (RS) and in situ (IS) instruments to record novel unprecedented measurements the solar atmosphere inner heliosphere. To take full advantage these new datasets, tools techniques must developed ease multi-instrument multi-spacecraft studies. In particular currently inaccessible low corona below two radii can only observed remotely. Furthermore used retrieve coronal plasma properties time three...
Coronal mass ejections (CMEs) are large-scale expulsions of coronal plasma and magnetic field propagating through the heliosphere. Because CMEs observed by white-light coronagraphs which, design, occult solar disc, supporting disc observations (e.g. in EUV, soft X-rays, Halpha radio) must be employed for study their source regions early development phases. We review key properties CME sources highlight a certain causal sequence effects that may occur whenever strong (flux-massive sheared)...
The European Union funded the FLARECAST project, that ran from January 2015 until February 2018. had a research-to-operations (R2O) focus, and accordingly introduced several innovations into discipline of solar flare forecasting. were: first, treatment hundreds physical properties viewed as promising predictors on equal footing, extending multiple previous works; second, use fourteen (14) different machine learning techniques, also to optimize immense Big Data parameter space created by...
This work is concerned with the design and analysis of hp-version discontinuous Galerkin (DG) finite element methods for boundary-value problems involving biharmonic operator. The first part extends unified approach Arnold et al. (2001/2002, SIAM J. Numer. Anal.,39, 1749-–1779) developed Poisson problem, to DG via an appropriate choice numerical flux functions fourth-order problems; as example, we retrieve interior penalty method by Süli & Mozolevski (2007, Comput. Methods Appl. Mech. Eng.,...
We introduce a residual-based posteriori error indicator for discontinuous Galerkin discretizations of the biharmonic equation with essential boundary conditions. show that is both reliable and efficient respect to approximation measured in terms natural energy norm under minimal regularity assumptions. validate performance within an adaptive mesh refinement procedure its asymptotic exactness range test problems.
Expanding on an earlier work that relied linear force-free (LFF) magnetic fields, we self-consistently derive the instantaneous free energy and relative helicity budgets of unknown three-dimensional nonlinear (NLFF) structure extending above a single known lower-boundary field vector. The proposed method does not rely detailed knowledge configuration but is general enough to employ only connectivity matrix lower boundary. calculation yields minimum consistent with this energy. directly...