Download or read book Magnetic Helicity Generation by Solar Differential Rotation written by and published by . This book was released on 2000 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observations of sunspots, active regions, filaments, coronal arcades, and interplanetary magnetic clouds indicate that the Sun preferentially exhibits left-handed, negative-helicity features in its northern hemisphere, and their opposite counterparts in the south, independent of sunspot cycle. We investigate quantitatively the generation of magnetic helicity by solar differential rotation acting on emerged bipolar sources of flux, using analytical and numerical methods. We find that the vast majority of bipoles absorb negative helicity in the northern hemisphere and positive helicity in the south, in accord with observations. After two to four solar rotation periods have elapsed, the helicity generated by differential rotation amounts to about 10% of the bipole's squared flux. Thus, each of the approximately 1 x 10(3) large bipolar regions emergent on the Sun during sunspot cycle 21 entrained about 1 x 10(43) Mx(2) of helicity in its 1 x 10(22) Mx of flux. We show further that the roughly 5 x 10(3) coronal mass ejections and associated interplanetary magnetic clouds that departed the Sun during the cycle carried off about 5 x 10(24) Mx of flux and 1 x 10(46) Mx(2) of helicity, within a factor of two of the estimates for solar production of these quantities. Evidently, differently rotation acting on emerged bipolar sources of flux can account quantitatively for the magnetic helicity balance of the Sun and the heliosphere, as well as for the observed prevalence of negative-helicity magnetic features in the north and positive-helicity features in the south.
Download or read book Magnetic Helicity at the Sun in Solar Wind and Magnetospheres written by Jörg Büchner and published by . This book was released on 2003 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Magnetic Helicity in Space and Laboratory Plasmas written by Michael R. Brown and published by American Geophysical Union. This book was released on 1999-01-26 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt: Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 111. Using the concept of magnetic helicity, physicists and mathematicians describe the topology of magnetic fields: twisting, writhing, and linkage. Mathematically, helicity is related to linking integrals, which Gauss introduced in the 19th century to describe the paths of asteroids in the sky. In the late 1970s the concept proved to be critical to understand laboratory plasma experiments on magnetic reconnection, dynamos, and magnetic field relaxation. In the late 1980s it proved equally important in understanding turbulence in the solar wind and the interplanetary magnetic field. During the last five years interest in magnetic helicity has grown dramatically in solar physics, and it will continue to grow as observations of vector magnetic fields become increasingly sophisticated.
Download or read book Multi Wavelength Investigations of Solar Activity IAU S223 written by International Astronomical Union. Symposium and published by Cambridge University Press. This book was released on 2004 with total page 766 pages. Available in PDF, EPUB and Kindle. Book excerpt: These Proceedings present the most recent results from the highly successful international solar space missions (SOHO, CORONAS-F, TRACE, RHESSI, YOHKOH) and ground observatories around the Earth, reported at the IAU Symposium 223 held in St. Petersburg, Russia, June 14-19, 2004. These include discussions of the current theories of solar dynamics and activity, new constraints provided by the multi-wavelength observations of the Sun from the interior to the heliosphere, as well as discussions of future coordinated plans and efforts of multi-wavelength investigations of the Sun. The Proceedings contain the material of seven plenary sessions and three round-table discussions
Download or read book Solar Magnetic Phenomena written by A. Hanslmeier and published by Springer Science & Business Media. This book was released on 2006-03-30 with total page 297 pages. Available in PDF, EPUB and Kindle. Book excerpt: The concept of summerschools and workshops at the Kanzelh· ohe · Solar Observatory, Karn · · ten, Austria, devotedtoup-to-datetopicsinsolarphysics has been proven to be extremely successful, and thus in August/September 2003 the third combined summerschool and workshop was held there. This book contains the proceedings of the Summerschool and Wo- shop "Solar Magnetic Phenomena" held from 25 August to 5 September 2003 at the Solar Observatory Kanzelh· ohe, · which belongs to the Institute for Geophysics, Astrophysics and Meteorology of the University of Graz, Austria. The book contains the contributions from six invited lecturers. They give an overview on the following topics: observations of the pho- sphere and chromosphere, solar?are observations and theory, coronal mass ejections and the relevance of magnetic helicity, high-energy radiation from the Sun, the physics of solar prominences and highlights from the SOHO mission. The lectures contain about 25 to 30 pages each and provide a valuableintroduction to the topics mentioned above. The comprehensive lists ofreferences at theendof each contribution enablethe interested reader to go into more detail. The second part of the book contains contributed papers. These - pers were presented anddiscussed in theworkshop sessions during the afternoons. The sessions stimulated intensive discussions between the p- ticipants and lecturers
Download or read book The Solar Activity Cycle written by André Balogh and published by Springer. This book was released on 2015-04-16 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: A collection of papers edited by four experts in the field, this book sets out to describe the way solar activity is manifested in observations of the solar interior, the photosphere, the chromosphere, the corona and the heliosphere. The 11-year solar activity cycle, more generally known as the sunspot cycle, is a fundamental property of the Sun. This phenomenon is the generation and evolution of magnetic fields in the Sun’s convection zone, the photosphere. It is only by the careful enumeration and description of the phenomena and their variations that one can clarify their interdependences. The sunspot cycle has been tracked back about four centuries, and it has been recognized that to make this data set a really useful tool in understanding how the activity cycle works and how it can be predicted, a very careful and detailed effort is needed to generate sunspot numbers. This book deals with this topic, together with several others that present related phenomena that all indicate the physical processes that take place in the Sun and its exterior environment. The reviews in the book also present the latest theoretical and modelling studies that attempt to explain the activity cycle. It remains true, as has been shown in the unexpected characteristics of the first two solar cycles in the 21st century, that predictability remains a serious challenge. Nevertheless, the highly expert and detailed reviews in this book, using the very best solar observations from both ground- and space based telescopes, provide the best possible report on what is known and what is yet to be discovered. Originally published in Space Science Reviews, Vol 186, Issues 1-4, 2014.
Download or read book Space Physics and Aeronomy Solar Physics and Solar Wind written by Nour E. Raouafi and published by John Wiley & Sons. This book was released on 2021-04-12 with total page 323 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive view of our Sun at the start of a new era in solar and heliospheric physics Humans have been observing and studying our Sun for centuries, yet much is still unknown about the processes that drive its behavior. Thanks to a new generation of space missions and ground telescopes, we are poised to dramatically increase our understanding of the Sun and its environment. Solar Physics and Solar Wind explores advances in solar and heliospheric research over recent decades, as well as the challenges that remain. This comprehensive reference work covers the solar interior, magnetism and radiation, plasma heating and acceleration, the sun's atmosphere, and solar activity. Volume highlights include: Explanations for processes in the solar interior New insights on the solar wind The challenges of measuring the Sun's magnetic field and its radiative output Description of solar atmospheric phenomena such as spicules and jets New developments in understanding flares and coronal mass ejections Ongoing research into how the solar corona is heated The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals. Find out more about the Space Physics and Aeronomy collection in this Q&A with the Editors in Chief
Download or read book Heliophysics Evolving Solar Activity and the Climates of Space and Earth written by Carolus J. Schrijver and published by Cambridge University Press. This book was released on 2010-09-23 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Heliophysics is a fast-developing scientific discipline that integrates studies of the Sun's variability, the surrounding heliosphere, and the environment and climate of planets. Over the past few centuries, our understanding of how the Sun drives space weather and climate on the Earth and other planets has advanced at an ever increasing rate. This 2010 volume, the last in this series of three heliophysics texts, focuses on long-term variability from the Sun's decade-long sunspot cycle and considers the evolution of the planetary system over ten billion years from a climatological perspective. Topics covered range from the dynamo action of stars and planets to processes in the Earth's troposphere, ionosphere, and magnetosphere and their effects on planetary climate and habitability. Supplemented by online teaching materials, it can be used as a textbook for courses or as a foundational reference for researchers in fields from astrophysics and plasma physics to planetary and climate science.
Download or read book Helicities in Geophysics Astrophysics and Beyond written by Kirill Kuzanyan and published by John Wiley & Sons. This book was released on 2023-12-12 with total page 275 pages. Available in PDF, EPUB and Kindle. Book excerpt: Helicities in Geophysics, Astrophysics, and Beyond Helicities play essential roles in numerous geophysical, astrophysical, and magnetohydrodynamic phenomena, thus are studied from various disciplinary viewpoints. Helicities in Geophysics, Astrophysics, and Beyond draws together experts from different research fields to present an interdisciplinary and integrated approach to helicity studies. This synthesis advances understanding of the fundamental physical processes underlying various helicity-related phenomena. Volume highlights include: Concise introduction to fundamental properties of helicities Recent developments and achievements in helicity studies Perspectives from different fields including geophysics, space physics, solar physics, plasma physics, atmospheric and nonlinear sciences A cohesive mathematical, physical, observational, experimental, and numerical strategy for helicity studies A synthesized framework for the application of helicity to real-world problems The American Geophysical Union promotes discovery in Earth and space science for the benefit of humanity. Its publications disseminate scientific knowledge and provide resources for researchers, students, and professionals.
Download or read book Helicity of the Solar Magnetic Field written by Sanjiv Kumar Tiwari and published by LAP Lambert Academic Publishing. This book was released on 2010-08 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic helicity is a physical quantity that measures the complexity in the field lines. It is given by a volume integral over scalar product of magnetic field and its vector potential. Direct computation of magnetic helicity in the solar atmosphere is not possible in want of observations to compute the volume integral. We have clarified the physical meaning of and its relation with the magnetic helicity. An analytical bipole was generated to study the effect of polarimetric noise on the estimation of various magnetic parameters. We then examined the fine structures of sunspots in terms of local current and . The concept of signed shear angle (SSA) has been introduced. Spatially averaged SSA (SASSA) gives actual twist present in a sunspot at an observed height irrespective of force-free nature and shape of sunspots. We find that there is no net current in the sunspots even in the presence of significant twist which is consistent with fibril-bundle structure of sunspot magnetic fields. The SASSA holds promise to be very useful in predicting the severity of solar flares. A good correlation has been found among the signs of helicity at different heights in the solar atmosphere.
Download or read book New Millennium Solar Physics written by Markus J. Aschwanden and published by Springer. This book was released on 2019-05-22 with total page 714 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a follow-on book to the introductory textbook "Physics of the Solar Corona" previously published in 2004 by the same author, which provided a systematic introduction and covered mostly scientific results from the pre-2000 era. Using a similar structure as the previous book the second volume provides a seamless continuation of numerous novel research results in solar physics that emerged in the new millennium (after 2000) from the new solar missions of RHESSI, STEREO, Hinode, CORONAS, and the Solar Dynamics Observatory (SDO) during the era of 2000-2018. The new solar space missions are characterized by unprecedented high-resolution imaging, time resolution, spectral capabilities, stereoscopy and tomography, which reveal the intricate dynamics of magneto-hydrodynamic processes in the solar corona down to scales of 100 km. The enormous amount of data streaming down from SDO in Terabytes per day requires advanced automated data processing methods. The book focuses exclusively on new research results after 2000, which are reviewed in a comprehensive manner, documented by over 3600 literature references, covering theory, observations, and numerical modeling of basic physical processes that are observed in high-temperature plasmas of the Sun and other astrophysical objects, such as plasma instabilities, coronal heating, magnetic reconnection processes, coronal mass ejections, plasma waves and oscillations, or particle acceleration.
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 Topics in Magnetohydrodynamic Topology Reconnection and Stability Theory written by David MacTaggart and published by Springer. This book was released on 2019-07-19 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book presents an advanced but accessible overview of some of the most important sub-branches of magnetohydrodynamics (MHD): stability theory, magnetic topology, relaxation theory and magnetic reconnection. Although each of these subjects is often treated separately, in practical MHD applications they are normally inseparable. MHD is a highly active field of research.The book is written for advanced undergraduates, postgraduates and researchers working on MHD-related research in plasma physics and fluid dynamics.
Download or read book Solar Terrestrial Magnetic Activity and Space Environment written by H. Wang and published by Elsevier. This book was released on 2002-11-20 with total page 475 pages. Available in PDF, EPUB and Kindle. Book excerpt: The COSPAR Colloquium on Solar-Terrestrial Magnetic Activity and Space Environment (STMASE) was held in the National Astronomy Observatories of Chinese Academy of Sciences (NAOC) in Beijing, China in September 10-12, 2001. The meeting was focused on five areas of the solar-terrestrial magnetic activity and space environment studies, including study on solar surface magnetism; solar magnetic activity, dynamical response of the heliosphere; space weather prediction; and space environment exploration and monitoring. A hot topic of space research, CMEs, which are widely believed to be the most important phenomenon of the space environment, is discussed in many papers. Other papers show results of observational and theoretical studies toward better understanding of the complicated image of the magnetic coupling between the Sun and the Earth, although little is still known little its physical background. Space weather prediction, which is very important for a modern society expanding into out-space, is another hot topic of space research. However, a long way is still to go to predict exactly when and where a disaster will happen in the space. In that sense, there is much to do for space environment exploration and monitoring. The manuscripts submitted to this Monograph are divided into the following parts: (1) solar surface magnetism, (2) solar magnetic activity, (3) dynamical response of the heliosphere, (4) space environment exploration and monitoring; and (5) space weather prediction. Papers presented in this meeting but not submitted to this Monograph are listed by title as unpublished papers at the end of this book.
Download or read book The Origin and Dynamics of Solar Magnetism written by M.J. Thompson and published by Springer Science & Business Media. This book was released on 2009-05-01 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Starting in 1995 numerical modeling of the Earth’s dynamo has ourished with remarkable success. Direct numerical simulation of convection-driven MHD- ow in a rotating spherical shell show magnetic elds that resemble the geomagnetic eld in many respects: they are dominated by the axial dipole of approximately the right strength, they show spatial power spectra similar to that of Earth, and the magnetic eld morphology and the temporal var- tion of the eld resembles that of the geomagnetic eld (Christensen and Wicht 2007). Some models show stochastic dipole reversals whose details agree with what has been inferred from paleomagnetic data (Glatzmaier and Roberts 1995; Kutzner and Christensen 2002; Wicht 2005). While these models represent direct numerical simulations of the fundamental MHD equations without parameterized induction effects, they do not match actual pla- tary conditions in a number of respects. Speci cally, they rotate too slowly, are much less turbulent, and use a viscosity and thermal diffusivity that is far too large in comparison to magnetic diffusivity. Because of these discrepancies, the success of geodynamo models may seem surprising. In order to better understand the extent to which the models are applicable to planetary dynamos, scaling laws that relate basic properties of the dynamo to the fundamental control parameters play an important role. In recent years rst attempts have been made to derive such scaling laws from a set of numerical simulations that span the accessible parameter space (Christensen and Tilgner 2004; Christensen and Aubert 2006).
Download or read book Multi Wavelength Observations of Coronal Structure and Dynamics written by Penny Martens and published by Elsevier. This book was released on 2002-10-21 with total page 461 pages. Available in PDF, EPUB and Kindle. Book excerpt: These are the Proceedings of the Yohkoh 10th Anniversary Meeting, a COSPAR Colloquium held in Kona, Hawaii, USA, on January 20-24, 2002. The title of the meeting was Multi-Wavelength Observations of Coronal Structure and Dynamics. In these proceedings the many and varied advances of the dynamics solar atmosphere in the past ten years of observations by Yohkoh have been reviewed.
Download or read book Mean Field Magnetohydrodynamics and Dynamo Theory written by F. Krause and published by Elsevier. This book was released on 2016-01-22 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mean-Field Magnetohydrodynamics and Dynamo Theory provides a systematic introduction to mean-field magnetohydrodynamics and the dynamo theory, along with the results achieved. Topics covered include turbulence and large-scale structures; general properties of the turbulent electromotive force; homogeneity, isotropy, and mirror symmetry of turbulent fields; and turbulent electromotive force in the case of non-vanishing mean flow. The turbulent electromotive force in the case of rotational mean motion is also considered. This book is comprised of 17 chapters and opens with an overview of the general concept of mean-field magnetohydrodynamics, followed by a discussion on the back-reaction of the magnetic field on motion; the structure of the turbulent electromotive force; homogeneous and two-scale turbulence; turbulent electromotive force in the case of rotational mean motion; and the dynamo problem of magnetohydrodynamics. The dynamo theory, which is based on mean-field magnetohydrodynamics, is explained and its applications to cosmical objects are described. The remaining chapters explore toroidal and poloidal vector fields; a simple model of an a-effect dynamo; and spherical models of turbulent dynamos as suggested by cosmical bodies. This monograph will be of interest to physicists.
