The Solar Activity Cycle

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.

Prof. Andé Balogh is Distinguished Research Fellow and Emeritus Professor of Space Physics at Imperial College, London and the past Director of the International Space Science Institute of Bern, Switzerland. His main research interests are solar and heliospheric magnetic fields, solar activity phenomena and the nature of heliospheric turbulence. Prof. Balogh has been a Principal Investigator on the Ulysses and Cluster space missions and is author and co-author of over 500 scientific papers on solar physics, space research and planetary physics; as well as editor of ten books, including eight volumes in Springer's Space Sciences Series of ISSI. His recent research has covered the measurements of the Sun's magnetic flux and its dependence on the solar activity cycle.

Dr. Hugh Hudson is a Senior Researcher in the Space Sciences Laboratory at the University of California, Berkeley and an Honorary Research Fellow in the School of Physics and Astronomy at the University of Glasgow. His main research interests are high energy solar physics: solar X-rays, solar flares and Coronal Mass Ejections, but he has carried out research and has published on all aspects of solar physics. He has been associated with several space-based solar observatories, in particular YOHKOH and RHESSI. His most recent research topics have included the investigation of the phenomena associated with the recent unusual solar activity cycle and the observation and interpretation of highly energetic phenomena in the solar atmosphere.

Prof. Kristóf Petrovay is Head of Department at the Department of Astronomy at Eötvös Loránd University, Budapest, Hungary. His main research interests are solar physics, astrophysical turbulence and magnetohydrodynamics. He has published widely on the topics of solar dynamo theory, magneto-convection in the Sun, the theory of sunspots, turbulence and turbulent diffusion in the Sun and in a broad range of astrophysical plasmas, as well as the origin and evolution of turbulent magnetic fields. In his recent publications, Prof. Petrovay has investigated models of the solar activity cycle and the physical processes that affect the operation of the solar dynamo.

Prof. Rudolf von Steiger is Director of the International Space Science Institute of Bern, Switzerland and a Professor at the University of Bern. His main research interests are all aspects of the solar wind, with special reference to its composition and the physical processes that determine its variability and evolution, as well as its dependence on solar phenomena and solar activity. Prof. von Steiger has used solar wind composition data from the Ulysses, ACE and SOHO space missions and has over 160 publications in refereed journals, covering the observational and physical aspects of the composition of the solar wind. He has edited 19 books, including 15 in Springer's Space Sciences Series of ISSI. Recently, he has refined the complex analysis of solar wind ion composition measurements to further improve their accuracy and thus to improve their diagnostic capabilities.