A5060445922- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Solar Radiation and Photovoltaics
- Geomagnetism and Paleomagnetism Studies
- Geophysics and Gravity Measurements
- Global Energy and Sustainability Research
- Earthquake Detection and Analysis
- Oil, Gas, and Environmental Issues
- Astronomy and Astrophysical Research
- CCD and CMOS Imaging Sensors
- Atomic and Molecular Physics
- Gamma-ray bursts and supernovae
- Photovoltaic System Optimization Techniques
- Meteorological Phenomena and Simulations
- Astrophysics and Star Formation Studies
- Currency Recognition and Detection
- Adaptive optics and wavefront sensing
- Radiation Therapy and Dosimetry
- Anomaly Detection Techniques and Applications
- Astronomical Observations and Instrumentation
- Atmospheric Ozone and Climate
- Optical Imaging and Spectroscopy Techniques
- Optical Polarization and Ellipsometry
Northumbria University
2018-2024
Trinity College Dublin
2008-2021
Paul Scherrer Institute
2012
FHNW University of Applied Sciences and Arts
2012
Max Planck Society
2007
Max Planck Institute for Solar System Research
2006-2007
Queen's University Belfast
2002-2006
Clark Atlanta University
2005
Smithsonian Astrophysical Observatory
2005
Aims. The Spectrometer Telescope for Imaging X-rays (STIX) on Solar Orbiter is a hard X-ray imaging spectrometer, which covers the energy range from 4 to 150 keV. STIX observes bremsstrahlung emissions solar flares and therefore provides diagnostics of hottest (⪆10 MK) flare plasma while quantifying location, spectrum, content flare-accelerated nonthermal electrons. Methods. To accomplish this, applies an indirect bigrid Fourier technique using set tungsten grids (at pitches 0.038 1 mm) in...
The kinematics of a globally propagating disturbance (also known as an ``EIT wave") is discussed using Extreme UltraViolet Imager (EUVI) data Solar Terrestrial Relations Observatory (STEREO). We show for the first time that impulsively generated has similar in all four EUVI passbands (304, 171, 195, and 284 A). In 304 A passband shows velocity peak 238+/-20 kms-1 within ~28 minutes its launch, varying acceleration from 76 ms-2 to -102 ms-2. This contains strong contribution Si XI line...
Solar flares occur in complex sunspot groups, but it remains unclear how the probability of producing a flare given magnitude relates to characteristics group. Here, we use Geostationary Operational Environmental Satellite X-ray and McIntosh group classifications from solar cycles 21 22 calculate average rates for each class these determine Poisson probabilities different magnitudes. Forecast verification measures are studied find optimum thresholds convert into yes/no predictions cycle 23...
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...
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)...
A new application of wavelet analysis is presented that utilizes the inherent phase information residing within complex Morlet transform. The technique applied to a weak solar magnetic network region, and temporal variation difference between TRACE 1700 Å SOHO/SUMER C II 1037 intensities shown. We present, for first time in an astrophysical setting, coherence, including comparison two methods testing real coherence against noise. example highlights advantage over more classical techniques,...
Simultaneous observations of explosive chromospheric evaporation are presented using data from the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Coronal Diagnostic Spectrometer (CDS) onboard SOHO. For first time, co-spatial imaging spectroscopy have been used to observe within a hard X-ray emitting region. RHESSI images spectra were determine flux non-thermal electrons accelerated during impulsive phase an M2.2 flare. Assuming thick-target model, injected electron...
Super-Alfv\'enic shock waves associated with coronal mass ejections (CMEs) can produce radio emission known as Type II bursts. In the absence of direct imaging, accurate estimates electron densities, magnetic field strengths and Alfv\'en speeds are required in order to calculate kinematics shocks. To date, 1D radial models have been used, but these not appropriate for shocks propagating non-radial directions. Here, we study a wave CME burst using 2D density speed maps determine locations...
For almost 20 years the physical nature of globally propagating waves in solar corona (commonly called "EIT waves") has been controversial and subject to debate. Additional theories have proposed over explain observations that did not agree with originally fast-mode wave interpretation. However, incompatibility made using Extreme-ultraviolet Imaging Telescope (EIT) onboard Solar Heliospheric Observatory interpretation was challenged by differing viewpoints from twin Terrestrial Relations...
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...
We analyse the intensity oscillations observed in gradual phase of a white-light flare on RS CVn binary II Peg. Fast Fourier Transform power spectra and Wavelet analysis reveal period 220 s. The reliability oscillation is tested using several criteria. Oscillating coronal loop models are used to derive physical parameters such as temperature, electron density magnetic field strength associated with loop. derived consistent near-simultaneous X-ray observations flare. There no evidence for...
We seek to clarify the nature of running penumbral (RP) waves: are they chromospheric trans-sunspot waves or a visual pattern upward-propagating waves? Full Stokes spectropolarimetric time series photospheric Si I λ10827 line and He λ10830 multiplet were inverted using Milne-Eddington atmosphere. Spatial pixels paired between outer umbral/inner photosphere chromosphere inclinations retrieved by inversion dual-height pairings line-of-sight velocity studied for signatures wave propagation...
Solar flares are extremely energetic phenomena in our System. Their impulsive, often drastic radiative increases, particular at short wavelengths, bring immediate impacts that motivate solar physics and space weather research to understand the point of being able forecast them. As data algorithms improve dramatically, questions must be asked concerning how well forecasting performs; crucially, we ask rigorously measure performance order critically gauge any improvements. Building upon...
Abstract Global EUV waves remain a controversial phenomenon more than 20 yr after their discovery by SOHO/EIT. Although consensus is growing in the community that they are most likely large-amplitude or shocks, wide variety of observations and techniques used to identify analyze them have led disagreements regarding physical properties interpretation. Here, we use 3D magnetohydrodynamic (MHD) model solar corona simulate an wave event on 2009 February 13 enable detailed validation various...
Dynamo activity in stars of different types is expected to generate magnetic fields with characteristics. As a result, differential study the characteristics loops broad sample may yield information about dynamo systematics. In absence direct imaging, certain physical parameters stellar loop can be extracted if flare occurs that loop. this paper we employ simple nonhydrodynamic approach introduced by Haisch, analyze homogeneous all flares could identify EUVE DS database: total 134 occurred...
One of the most dramatic manifestations solar activity are large-scale coronal bright fronts (CBFs) observed in extreme ultraviolet (EUV) images atmosphere. To date, energetics and kinematics CBFs remain poorly understood, due to low image cadence sensitivity previous EUV imagers limited methods used extract features. In this paper, trajectory morphology was determined order investigate varying properties a sample CBFs, including their pulse shape, dispersion, dissipation. We have developed...
Oscillations in network bright points (NBPs) are studied at a variety of chromospheric heights. In particular, the three-dimensional variation NBP oscillations is using image segmentation and cross-correlation analysis between images taken light Ca II K3, Hα core, Mg I b2, b1 - 0.4 Å. Wavelet used to isolate wave packets time search for height-dependent delays that result from upward- or downward-directed traveling waves. each studied, we find evidence kink-mode waves (1.3, 1.9 mHz), up...
The study of solar eruptive events and associated phenomena is great importance in the context heliophysics. Coronal mass ejections (CMEs) coronal waves are energetic manifestations restructuring magnetic field motion plasma. Characterising this vital for deriving dynamics these thus understanding physics driving their initiation propagation. development use appropriate methods measuring event kinematics therefore imperative. Traditional approaches to CME wave do not return wholly accurate...
Most solar flares originate in sunspot groups, where magnetic field changes lead to energy build-up and release. However, few flare-forecasting methods use information of sunspot-group evolution, instead focusing on static point-in-time observations. Here, a new forecast method is presented based upon the 24-h evolution McIntosh classification groups. Evolution-dependent ≥C1.0 ≥M1.0 flaring rates are found from NOAA-numbered groups over December 1988–June 1996 (Solar Cycle 22; SC22) before...