The Origin and Dynamics of Solar Magnetism (Space Sciences Series of ISSI Book 32)

The articles collected in this volume present all aspects of solar magnetism: from its origin in the solar dynamo to its evolution and dynamics that create the variability of solar phenomena, its well-known 11-year activity cycle that leads to the ever-changing pattern of sunspots and active regions on the Sun. Several contributions deal with the solar dynamo, the driver of many solar phenomena. Other contributions treat the transport and emergence of the magnetic flux through the outer layers of the Sun. The coupling of magnetic fields from the surface to the solar corona and beyond is also described, together with current studies on the predictability of solar activity. This book is aimed at researchers and graduate students working in solar physics and space science. It provides a full review of our current understanding of solar magnetism by the foremost experts in the field. Front Matter....Pages i-iv Introduction to Solar Magnetism: The Early Years....Pages 1-14 Solar Magnetism: The State of Our Knowledge and Ignorance....Pages 15-24 Chaos and Intermittency in the Solar Cycle....Pages 25-51 The Solar Dynamo....Pages 53-66 Flux-Transport Solar Dynamos....Pages 67-75 The Solar Dynamo: The Role of Penetration, Rotation and Shear on Convective Dynamos....Pages 77-86 Advances in Theory and Simulations of Large-Scale Dynamos....Pages 87-104 Planetary Dynamos from a Solar Perspective....Pages 105-126 Observations of Photospheric Dynamics and Magnetic Fields: From Large-Scale to Small-Scale Flows....Pages 127-149 Large Scale Flows in the Solar Convection Zone....Pages 151-173 Photospheric and Subphotospheric Dynamics of Emerging Magnetic Flux....Pages 175-195 The Topology and Behavior of Magnetic Fields Emerging at the Solar Photosphere....Pages 197-212 Sunspots: From Small-Scale Inhomogeneities Towards a Global Theory....Pages 213-228 Recent Evidence for Convection in Sunspot Penumbrae....Pages 229-247 Helioseismology of Sunspots: A Case Study of NOAA Region 9787....Pages 249-273 Small-Scale Solar Magnetic Fields....Pages 275-315 Coupling from the Photosphere to the Chromosphere and the Corona....Pages 317-350 Magnetic Flux Emergence, Activity, Eruptions and Magnetic Clouds: Following Magnetic Field from the Sun to the Heliosphere....Pages 351-381 Coronal Holes and Open Magnetic Flux....Pages 383-399 Solar Cycle Forecasting....Pages 401-412 Coronal Magnetism: Difficulties and Prospects....Pages 413-421 ISSI Workshop on Solar Magnetism: Concluding Remarks....Pages 423-428 Back Matter....Pages 431-432 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). Treats various aspects of solar magnetism, from its origin in the solar dynamo to its evolution and dynamics that create the variability of solar phenomena, from its well-known 11-year activity cycle to the ever-changing pattern of sunspots and active regions on the Sun