GLOBAL SOLAR MAGNETIC-FIELDS

The global solar magnetic field greatly affects the corona, heliosphere, and terrestrial environment as well as revealing much about the Sun itself. It may be useful to think of the global field in two ways: as an aggregate of many small scale processes and as an entity. When considering the origin and evolution of the global field, one immediately focuses on the smaller-scale features and processes that it comprises. These include the emergence of active regions, the interaction of new and existing flux patterns, the distortion and dispersal of flux over the surface by convective motions, the phenomena that produce the emergence of patterns with various periods, and the influence of convection and rotation at various depths on flux tubes. When contemplating the effects of the global field, one often focuses on it as an entity or on its large-scale features. Examples are the reversal of the polar fields, the asymmetry between the north and south hemispheres, the dipole or quadrupole structure of the coronal field and its observation at the Earth as 2 or 4 polarity sectors, and the rigid rotation seen in coronal holes. Both views help us appreciate the significance of the global field.