Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 34 for “"Solar flare"”.
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Solar flare gamma-ray spectroscopy with CGRO-COMPTEL
<p>The X-ray and gamma-ray emission from solar flares provides important information about high-energy particles in solar flares. Energetic protons and ions interact with the solar atmosphere, giving rise to nuclear line emission at MeV energies and higher energy photons from the decay of neutral …
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Solar flare effects observed over Jicamarca during MST-ISR experiments
A study of solar flare effects observed at the Jicamarca Radio Observatory (JRO) will be presented. The observations were made while the Jicamarca radar was conducting combined observations in mesosphere-stratosphere-troposphere (MST) and incoherent scatter radar (ISR) modes. Combined MST-ISR …
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Analysis and Modelling of a Type II White-light Solar Flare
Type II white-light flares (WLFs) are rare impulsive events in solar atmosphere observed across the electromagnetic spectrum, but without the characteristic emission in hydrogen lines. A unique set of multi-instrument observations is presented with broad wavelength range spectra in the visible and …
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Validation of solar flare forecasting & evolution of magnetic helicity of two active regions
… two components: (1) Validation of the NJIT flare-forecasting model that was established in recent years is carried out based on the statistical correlation between solar magnetic parameters and flare productivity of active regions (ARs). 378 ARs are examined, comparing observation with …
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Using active contours for automated tracking of UV and EUV solar flare ribbons
Solar flare UV and EUV images show elongated bright ``ribbons'' that move over time. If these ribbons are assumed to locate the footpoints of magnetic field lines reconnecting in the corona then it is clear that studying their evolution can provide an important insight into the reconnection …
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Characterization and Modeling of Solar Flare Effects in the Ionosphere Observed by HF Instruments
… frequency (HF, 3-30 MHz) radiowave propagation. Solar activities, such as solar flares, radiation storms, coronal mass ejections (CMEs), alter the state of the ionosphere, a phenomenon known as Sudden Ionospheric Disturbance (SID), that can severely disrupt HF radio communication links by …
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Diagnostics of solar flare energetic particles: neglected hard X-ray processes and neutron astronomy in the inner heliosphere
… have been studying some energetic processes in solar flares. On our work on hard X-ray (HXR) emission from flares, we have shown that non-thermal recombination emission can compare with the bremsstrahlung HXR flux for certain flare conditions. In this thesis, we show spectral features …
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An analysis of changes in the magnetic field of active region 9415 after the 2001 April 6 Solar Flare
… current understanding of the correlation between solar flares and magnetic flux change. The average gradient of the magnetic flux around the neutral line of Active Region 9415 and the locations of the magnetic flux centers-of-mass in both polarities in AR 9415 were determined. Subsequent to the …
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Automatic prediction of solar flares and super geomagnetic storms
… may produce many harmful effects on Earth. Solar flares and Coronal Mass Ejections (CMEs) are believed to be the major causes of geomagnetic storms. Thus, establishing a real time forecasting method for them is very important in space weather study. The topics covered in this dissertation …
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Auroral radio absorption : modelling and prediction
… closed field lines and (>MeV) protons from the solar wind are responsible for enhanced high frequency radiowave absorption in the high latitude ionosphere. Measuring the propagation of radio waves through the ionosphere has been utilised for investigating particle precipitation into the upper …
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Evolution of 3-d magnetic topology in flare-productive active regions
Solar eruptive phenomena, such as flares and coronal mass ejections (CMEs), derive their energy from complex magnetic fields and are the principal source of disturbances that affect space weather. Although physical mechanism and dynamic morphology of flares have been a subject of intense research, …
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An analysis of reconnection dynamics in an eruptive flare model
… model for current sheets that form during solar flares. The model uses a method developed by B. V. Somov & V. S. Titov for Petschek-type reconnection. The first part of this dissertation provides a detailed analysis of the Somov-Titov model, its assumptions, strengths and weaknesses. We …
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Hard X-ray diagnostics of particle acceleration and energy release in solar flares and coronal jets
… This dissertation investigates two forms of solar activity capable of accelerating particles to high energies—solar flares and coronal jets, both of which are driven by magnetic reconnection. Hard X-ray (HXR) emissions, produced via bremsstrahlung, provide direct diagnostics of thermal plasma …
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Sensing impacts to the Earth-ionosphere waveguide from terrestrial and space weather
… of this region is perturbed by dynamic solar processes. Solar flares and precipitating radiation belt particles enhance low-altitude ionization, causing communication blackouts, and generating ozone-destroying radicals in the mesosphere. In order to quantify the global impacts of solar …
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Development of advanced algorithms to detect, characterize and forecast solar activities
Study of the solar activity is an important part of space weather research. It is facing serious challenges because of large data volume, which requires application of state-of-the-art machine learning and computer vision techniques. This dissertation targets at two essential aspects in space …
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Application of statistical analysis techniques to solar and stellar phenomena
Currently, solar observers are investigating spectroscopic images of the Sun's outermost atmosphere (the corona), which are challenging long-held views on the density and temperature structure of this environment. The corona is "filled" with magnetic strands but determining their precise nature is …
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Coronal magnetic energy release by current sheet reconnection
… investigate the rapid release of energy in the solar corona, with a particular view to understanding the solar flare in which magnetic reconnection is thought to play a key role. A review of existing reconnection solutions is given in Chapters 2 and 3, with new analytic and numeric results are …
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Measurements of the 2001 April 15 and 2005 January 20 ground -level enhancements by the Milagro water Cerenkov detector
… Although the accelerating source is tied to the solar magnetic field, the physical process responsible continues to be debated. Essential information about the location and nature of the acceleration mechanism can be obtained from measurements of the highest-energy particles.</p><p>The Milagro …
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