While the emergence and evolution of solar surface magnetic flux reveals what goes on in the solar interior, the interplay of convection and magnetic field in the photosphere regulates the field dispersal and drives the instabilities which heat the outer solar atmosphere. This book presents a synthesis between observers and theorists, both with regard to the magnetic elements which make up solar magnetic fields (ranging from tiny flux tubes to whole active regions), and to the surface patterns in which these elements display properties of the subsurface dynamo. A major breakthrough comes from numerical simulations. Modelling of flux concentration, flux tube dynamics, penumbral toplogy, umbral fine structure, and so on, turns solar physics into an experimental science. The reviews and research papers in this volume provide an overview of the solar frontier of astrophysical magnetohydrodynamics. The elements and patterns of solar surface magnetism contain much information about the subsurface solar dynamo, as well as on the magnetically-dominated energy budget and structuring of the outer solar atmosphere. The volume treats high-resolution solar polarimetry, the physics of solar magnetic elements, and the information contained in their patterns of emergence on the solar surface in depth, with a balance between theoretical and observational studies.

Solar Physics publishes up to two Topical Issues per year that focus on areas of especially vigorous and active research. The present Topical Issue contains papers of recent results on the solar corona, as well as on the transition region and low solar wind. The majority of these papers, which were all refereed in accordance with the standards of Solar Physics, were presented in August 1999 at a workshop held in Monterey, California. The authors were offered the opportunity to present relevant parts of their contributions on an accompanying CD ROM of this Topical Issue. The Sun's magnetic field is responsible for the spectacularly dynamic and intri cate phenomenon that we call the corona. The past decade has seen an enormous increase in our understanding of this part of the solar outer atmosphere, both as a result of observations and because of rapid advances in numerical studies. The Yohkoh satellite has observed the Sun now for over eight years, producing spectac ular sequences of images that convey the complexity of the corona. The imaging and spectroscopic instruments on SOHO have added information on the cooler part of the corona. And since April of 1998 TRACE has given us very high resolution images of the 1-2 MK corona, at cadences that allow detailed observations of field oscillations, loop evolution, mass ejecta, etc.

Solar Physics publishes up to two TopicalIssues per year that focus on areas of especially vigorousand activeresearch. The present TopicalIssue containspapers of recent results on the solar corona, as well as on the transition region and low solar wind. The majority of these papers, which were all refereed in accordance withthe standards of Solar Physics, werepresentedin August 1999at a workshop heldin Monterey, California. TheSun's magneticfieldis responsibleforthe spectacularly dynamicand intri- cate phenomenonthat we call the corona. The past decade has seen an enormous increase in our understanding of this part of the solar outer atmosphere, both as a result of observations and because of rapid advances in numerical studies.The Yohkoh satellitehasobservedthe Sun nowfor overeightyears, producingspectac- ular sequences of images that conveythe complexity of the corona. The imaging andspectroscopic instrumentsonSOHOhaveaddedinformationonthecoolerpart of the corona. Andsince April of 1998TRACEhas givenus very high resolution imagesof the 1-2 MKcorona, atcadencesthat allowdetailedobservations of field oscillations, loopevolution, mass ejecta, etc. The papers of thisTopicalIssue revolvearoundone keytheme:the entire outer atmosphereof the Sun is intrinsicallydynamic, evolvingso rapidly that even the concept of a single local temperaturefor a single fluid often breaks down. More- over, the corona is an intrinsicallynonlinearand non-localmedium.These aspects are discussedin thisTopicalIssue, includingboth papers that reviewrecentdevel- opments(both basedon observations and on theoretical/numerical modeling), and original research papers based on observations from many different observatories. Weareverygratefulto the manyrefereeswhoweregivenlittletimeto respond, andto the staffofKluwerfor theproductionofthetopicalissuesandtheirreprints. Thepapers acceptedforthisTopicalIssueadduptosuchavolumethattheyhaveto be distributedovertwo TopicalIssues of SolarPhysics (December 1999and April 2000),which are reprintedin two bound volumes, of whichthis is the second.

Observations of the solar magnetic field are largely confined to the radiation emitted from the photosphere, the thin layer of the solar atmosphere which we call "the solar surface." It is from solar surface observations that we must infer the internal structure and the internal magnetohydrodynamic processes that lead to the multitude of fascinat ing phenomena of solar magnetic activity, and from solar surface observations we must also infer the interplay of convection and magnetism that regulates field dispersal, drives the heating of the outer-atmospheric plasma, and generates the solar wind. There is much to be learned from solar surface magnetism in physics and astrophysics; currently, there are rapid developments in this exciting field. The workshop of which this volume contains the proceedings aimed at a synthesis between observers and theorists, both with regard to the discrete elements that are the building blocks of solar magnetism and with regard to the larger-scale spatial and temporal patterns in which the magnetic elements emerge and disappear. The workshop was held during November 1-5, 1993 in Soesterberg, The Netherlands. The fifty participants took a very active part in making the workshop quite a lively one. The articles in these proceedings cover most of the oral and poster presentations, excepting a dozen soon to be published elsewhere."

Solar Physics publishes up to two TopicalIssues per year that focus on areas of especially vigorousand activeresearch. The present TopicalIssue containspapers of recent results on the solar corona, as well as on the transition region and low solar wind. The majority of these papers, which were all refereed in accordance withthe standards of Solar Physics, werepresentedin August 1999at a workshop heldin Monterey, California. TheSun's magneticfieldis responsibleforthe spectacularly dynamicand intri- cate phenomenonthat we call the corona. The past decade has seen an enormous increase in our understanding of this part of the solar outer atmosphere, both as a result of observations and because of rapid advances in numerical studies.The Yohkoh satellitehasobservedthe Sun nowfor overeightyears, producingspectac- ular sequences of images that conveythe complexity of the corona. The imaging andspectroscopic instrumentsonSOHOhaveaddedinformationonthecoolerpart of the corona. Andsince April of 1998TRACEhas givenus very high resolution imagesof the 1-2 MKcorona, atcadencesthat allowdetailedobservations of field oscillations, loopevolution, mass ejecta, etc. The papers of thisTopicalIssue revolvearoundone keytheme:the entire outer atmosphereof the Sun is intrinsicallydynamic, evolvingso rapidly that even the concept of a single local temperaturefor a single fluid often breaks down. More- over, the corona is an intrinsicallynonlinearand non-localmedium.These aspects are discussedin thisTopicalIssue, includingboth papers that reviewrecentdevel- opments(both basedon observations and on theoretical/numerical modeling), and original research papers based on observations from many different observatories. Weareverygratefulto the manyrefereeswhoweregivenlittletimeto respond, andto the staffofKluwerfor theproductionofthetopicalissuesandtheirreprints. Thepapers acceptedforthisTopicalIssueadduptosuchavolumethattheyhaveto be distributedovertwo TopicalIssues of SolarPhysics (December 1999and April 2000),which are reprintedin two bound volumes, of whichthis is the second.

Magnetic activity in the sun and similar stars results in a wealth of phenomena--including starspots, nonradiatively heated outer atmospheres, activity cycles, deceleration of rotation rates, and even, in close binaries, stellar cannibalism. This volume uniquely combines studies of the sun with those of other stars to provide a comprehensive picture of stellar magnetic activity. Coverage brings together recent results in solar and stellar studies to provide an illuminating, new view of the subject. Key topics include radiative transfer, convective simulations, dynamo theory, outer-atmospheric heating, stellar winds and angular momentum loss. Researchers are provided with a state-of-the-art review of this exciting field. Graduate students in astrophysics and plasma physics will find the volume an ideal introduction to the subject. The book will also interest researchers studying the connection of solar Sctivity with the Earth's climate change, such as geologists, planetary scientists and atmospheric scientists.