Download or read book Modelling Solar Coronal Magnetic Field Evolution written by Erin Elizabeth Goldstraw and published by . This book was released on 2019 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Magnetohydrodynamic Modeling of the Solar Corona and Heliosphere written by Xueshang Feng and published by Springer. This book was released on 2019-08-01 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book covers intimately all the topics necessary for the development of a robust magnetohydrodynamic (MHD) code within the framework of the cell-centered finite volume method (FVM) and its applications in space weather study. First, it presents a brief review of existing MHD models in studying solar corona and the heliosphere. Then it introduces the cell-centered FVM in three-dimensional computational domain. Finally, the book presents some applications of FVM to the MHD codes on spherical coordinates in various research fields of space weather, focusing on the development of the 3D Solar-InterPlanetary space-time Conservation Element and Solution Element (SIP-CESE) MHD model and its applications to space weather studies in various aspects. The book is written for senior undergraduates, graduate students, lecturers, engineers and researchers in solar-terrestrial physics, space weather theory, modeling, and prediction, computational fluid dynamics, and MHD simulations. It helps readers to fully understand and implement a robust and versatile MHD code based on the cell-centered FVM.
Download or read book Development and Application of a Global Magnetic Field Evolution Model for the Solar Corona written by Anthony Robinson Yeates and published by . This book was released on 2008 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulation of Solar Coronal Magnetic Fields written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-20 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many aspects of solar activity are believed to be due to the stressing of the coronal magnetic field by footpoint motions at the photosphere. The results are presented of a fully spectral numerical simulation which is the first 3-D time dependent simulation of footpoint stressing in a geometry appropriate for the corona. An arcade is considered that is initially current-free and impose a smooth footpoint motion that produces a twist in the field of approx 2 pi. The footprints were fixed and the evolution was followed until the field relaxes to another current-free state. No evidence was seen for any instability, either ideal or resistive and no evidence for current sheet formation. The most striking feature of the evolution is that in response to photospheric motions, the field expands rapidly upward to minimize the stress. The expansion has two important effects. First, it suppresses the development of dips in the field that could support dense, cool material. For the motions assumed, the magnetic field does not develop a geometry suitable for prominence formation. Second, the expansion inhibits ideal instabilities such as kinking. The results indicate that simple stearing of a single arcade is unlikely to lead to solar activity such as flares or prominences. Effects are discussed that might possibly lead to such activity. Dahlburg, Russell B. and Antiochos, Spiro K. and Zang, T. A. Langley Research Center ...
Download or read book Structure and Dynamics of the Coronal Magnetic Field written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last few years have seen a marked increase in the sophistication of models of the solar corona. This has been brought about by a confluence of three key elements. First, the collection of high-resolution observations of the Sun, both in space and time, has grown tremendously. The SOHO (Solar Heliospheric Observatory) mission is providing additional correlated high-resolution magnetic, white-light and spectroscopic observations. Second, the power and availability of supercomputers has made two- and three-dimensional modeling routine. Third, the sophistication of the models themselves, both in their geometrical realism and in the detailed physics that has been included, has improved significantly. The support from our current Space Physics Theory grant has allowed us to exploit this confluence of capabilities. We have carried out direct comparisons between observations and models of the solar corona. The agreement between simulated coronal structure and observations has verified that the models are mature enough for detailed analysis, as we will describe. The development of this capability is especially timely, since observations obtained from three space missions that are underway (Ulysses, WIND and SOHO) offer an opportunity for significant advances in our understanding of the corona and heliosphere. Through this interplay of observations and theory we can improve our understanding of the Sun. Our achievements thus far include progress modeling the large-scale structure of the solar corona, three-dimensional models of active region fields, development of emerging flux and current, formation and evolution of coronal loops, and coronal heating by current filaments. VanHoven, Gerard and Schnack, Dalton D. Goddard Space Flight Center NAG5-2257...
Download or read book Evolution of Coronal Magnetic Fields written by Julia Katharina Thalmann and published by . This book was released on 2010 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solar Flare Magnetic Fields and Plasmas written by Yuhong Fan and published by Springer Science & Business Media. This book was released on 2012-03-28 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is devoted to the dynamics and diagnostics of solar magnetic fields and plasmas in the Sun’s atmosphere. Five broad areas of current research in Solar Physics are presented: (1) New techniques for incorporating radiation transfer effects into three-dimensional magnetohydrodynamic models of the solar interior and atmosphere, (2) The connection between observed radiation processes occurring during flares and the underlying flare energy release and transport mechanisms, (3) The global balance of forces and momenta that occur during flares, (4) The data-analysis and theoretical tools needed to understand and assimilate vector magnetogram observations and (5) Connecting flare and CME phenomena to the topological properties of the magnetic field in the Solar Atmosphere. The role of the Sun’s magnetic field is a major emphasis of this book, which was inspired by a workshop honoring Richard C. (Dick) Canfield. Dick has been making profound contributions to these areas of research over a long and productive scientific career. Many of the articles in this topical issue were first presented as talks during this workshop and represent substantial original work. The workshop was held 9 – 11 August 2010, at the Center Green campus of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. This volume is aimed at researchers and graduate students active in solar physics, solar-terrestrial physics and magneto-hydrodynamics. Previously published in Solar Physics journal, Vol. 277/1, 2012.
Download or read book Numerical Simulation of Solar Coronal Magnetic Fields written by and published by . This book was released on 1990 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many aspects of solar activity are believed to be due to the stressing of the coronal magnetic field by footpoint motions at the photosphere. We present the results of a fully spectral numerical simulation which, to our knowledge, is the first 3-d time dependent simulation of footpoint stressing in a geometry appropriate for the corona. We consider an arcade that is initially current-free and impose a smooth footpoint motion that produces a twist in the field of approximately 2 pi. We then fix the footpoints and follow the evolution until the field relaxes to another current-free state. We see no evidence for any instability, either ideal or resistive and no evidence for current sheet formation. The most striking feature of the evolution is that in response to photospheric motions, the field expands rapidly upward to minimize the stress. The expansion has two important effects. First, it suppresses the development of dips in the field that could support dense, cool material. For the motions that we assume, the magnetic field does not develop a geometry suitable for prominence formation. Second, the expansion inhibits ideal instabilities such as kinking. Our results indicate that simple stearing of a single arcade is unlikely to lead to solar activity such as flares or prominences. We discuss effects that might possibly lead to such activity.
Download or read book Connecting Coronal Holes and Open Magnetic Flux Through Observation and Models of Solar Cycles 23 and 24 written by Christopher Alan Lowder and published by . This book was released on 2015 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coronal holes are regions of the Sun's surface that map the footprints of open magnetic field lines as they extend into the corona and beyond, into the heliosphere. Mapping their footprint 'dance' throughout the solar cycle is crucial for understanding this open field contribution to space weather. Coronal holes provide just this proxy. Using a combination of SOHO:EIT, SDO:AIA, and STEREO:EUVI A/B extreme ultraviolet (EUV) observations from 1996-2014, coronal holes can be automatically detected and characterized throughout this span, enabling long-term solar-cycle-timescale study. I have developed a routine to enable automated computer recognition of coronal hole boundaries from these EUV data. The combination of SDO:AIA and STEREO:EUVI A/B data provides a new viewpoint on understanding coronal holes. As the two STEREO spacecraft drift ahead of and behind the Earth in their orbits, respectively, they are able to peek 'around the corner', providing the ability to image nearly the entire solar atmosphere in EUV wavelengths, using SDO data in conjunction. On the far-side of the Sun, evolving open magnetic field structures impact space weather, despite being unobservable until rotating into view by Earth. By combining our numerical models of solar magnetic field evolution with coronal hole observations, comparison of far-side dynamics becomes possible. Model constraints and boundary conditions are more easily fine-tuned with these global observations. Long-term and transient coronal holes both play an important role as observational signatures of open magnetic field. Understanding the dynamics of boundary changes and distribution throughout the solar cycle yields important insight into connecting models of open magnetic field.
Download or read book The Solar Dynamics Observatory written by Phillip Chamberlin and published by Springer Science & Business Media. This book was released on 2012-05-05 with total page 405 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is dedicated to the Solar Dynamics Observatory (SDO), which was launched 11 February 2010. The articles focus on the spacecraft and its instruments: the Atmospheric Imaging Assembly (AIA), the Extreme Ultraviolet Variability Experiment (EVE), and the Helioseismic and Magnetic Imager (HMI). Articles within also describe calibration results and data processing pipelines that are critical to understanding the data and products, concluding with a description of the successful Education and Public Outreach activities. This book is geared towards anyone interested in using the unprecedented data from SDO, whether for fundamental heliophysics research, space weather modeling and forecasting, or educational purposes. Previously published in Solar Physics journal, Vol. 275/1-2, 2012. Selected articles in this book are published open access under a CC BY-NC 2.5 license at link.springer.com. For further details, please see the license information in the chapters.
Download or read book Coronal Magnetometry written by Sarah E. Gibson and published by Frontiers Media SA. This book was released on 2017-07-11 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetism defines the complex and dynamic solar corona. It determines the magnetic loop structure that dominates images of the corona, and stores the energy necessary to drive coronal eruptive phenomena and flare explosions. At great heights the corona transitions into the ever-outflowing solar wind, whose speed and three-dimensional morphology are controlled by the global coronal magnetic field. Coronal magnetism is thus at the heart of any understanding of the nature of the corona, and essential for predictive capability of how the Sun affects the Earth. Coronal magnetometry is a subject that requires a concerted effort to draw together the different strands of research happening around the world. Each method provides some information about the field, but none of them can be used to determine the full 3D field structure in the full volume of the corona. Thus, we need to combine them to understand the full picture. The purpose of this Frontiers Research Topic on Coronal Magnetometry is to provide a forum for comparing and coordinating these research methods, and for discussing future opportunities.
Download or read book Magnetic Flux Transport Simulations written by Graeme Robert Cook and published by . This book was released on 2011 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evolution of Coronal Mass Ejections from the Sun to 1 AU written by Valbona Kunkel and published by . This book was released on 2012 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structure and Development of Solar Active Regions written by K.O. Kiepenheuer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt: K. O. KIEPENHEUER ( Fraunhofer Institut, Freiburg i. Br., Germany) The present symposium, to my knowledge the largest ever held in the field of solar research (170 astronomers from 21 countries) was held in the building of the Hun garian Academy of Sciences in Budapest from September 4 to 8, 1967. It was the 35th symposium organized and sponsored by the International Astronomical Union. The majority of participants were financedfrom national sources. The Organizing Commit tee consisted of K. O. Kiepenheuer (Chairman), L. Davis, L. Dezso (Local Organizer), A.D. Fokker, R. Michard, A.B. Severny, H.J. Smith, Z. Svestka, and H. Tanaka. In order to ensure prompt publication, the manuscripts had to be supplied by the authors 1 month after the meeting. The discussions have been recorded on tape. Their reproduction in this book, however, is based almost completely on the contributors' writing down their comments and questions on the spot. Two special projects have been reported and discussed shortly during the sym posium: The world wide project 'Cooperative Study of Solar Active Regions' (CSSAR) organized by Dr. R. Michard, under the auspices of the IAU, which has put at the disposal of our solar community a precious observing material on Active Regions over a period of 6 months.
Download or read book The Dynamics of Coronal Magnetic Structures written by Wilhelmus Jacobus Weber and published by . This book was released on 1978 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory and Simulation of the Evolution of the Large scale Solar Magnetic Field written by Carl Richard DeVore and published by . This book was released on 1986 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Magnetic Solar Photosphere and Corona written by Xudong Sun and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Sun's magnetic field drives the dynamic behavior of its atmosphere and modulates the space weather conditions that we experience at the Earth. This dissertation focuses on the recent advances in understanding magnetic field measurements, static-state modeling of the corona, and their applications in space weather forecasting. We revisit the full-Sun line-of-sight magnetic field data archive from the Michelson Doppler Imager (MDI). Using the Wang-Sheeley-Arge (WSA) model coupled with the potential field source surface (PFSS) model, we retrospectively optimize the space weather forecasting scheme for the MDI data. We evaluate the long-term performance of the model: the solar wind speed prediction near the Earth yields a 16% error over solar cycle 23, and the interplanetary magnetic field polarity is correctly predicted 81% of time. The prediction accuracy is strongly correlated with the activity cycle phase. We design a new interpolation scheme to estimate the unobserved magnetic field in the polar region which improves the solar wind speed prediction. Making use of the PFSS model and the MDI data, we characterize the global-scale coronal and heliospheric magnetic field structure and its evolution during cycle 23. The modeled features agree reasonably well with remote-sensing and in-situ observations. The recent cycle displayed an extended minimum activity period, whose peculiar heliospheric consequences can be partly explained by a reduction of the polar magnetic field strength. The PFSS model may need to adopt a smaller source surface radius to better fit some observations. We use a series of vector magnetograms from the Heliospheric and Magnetic Imager (HMI) to study the magnetic field and energy evolution of NOAA active region (AR) 11158. With the aid of a non-linear force-free field (NLFFF) extrapolation, we find substantial electric current and magnetic free energy increase during early flux emergence. The computed free energy is enough to power the ensuing X-class flare. We find a step-wise energy decrease during the flare, but the value is likely underestimated. The new observations confirm the rapid and irreversible change of the photospheric field during a major flare. The horizontal field was enhanced, with the field becoming more inclined and more parallel to the polarity inversion line. Such change is consistent with the conjectured coronal field "implosion". Observation and modeling of this AR also illustrates the important role of magnetic topology. A small bipole emerged in the sunspot complex, subsequently created a quadrupolar flux system, and induced a series of eruptions with highly inclined trajectory. Field extrapolation suggests complicated magnetic connectivity with a coronal null point, which is supported by coronal observations. Owing to the asymmetrical photospheric flux distribution, the confining magnetic pressure decreases much faster horizontally than upward, and thus likely guided the non-radial eruption during its initial stage.
