On the global structure of the heliospheric magnetic field

Abstract

The structure of the heliospheric magnetic field, an extension of the solar magnetic field, is influenced by dynamic processes that occur on the solar surface and in the solar corona. Recent work has demonstrated that the interplay between the differential rotation of the photosphere and the nonradial expansion of the solar wind in the corona can lead to large-scale, systematic motions of the coronal magnetic field. These motions, in turn, alter the large-scale configuration of the heliospheric field, from that of the standard spiral structure. A critical analysis is presented of the processes that drive these coronal motions and of possible effects that could limit them. The model for the heliospheric magnetic field driven by coronal motions is also contrasted with other approaches and descriptions of the coronal and heliospheric magnetic field, e.g., potential field models for the coronal magnetic field. Finally, the challenges and opportunities for observing the differences between the heliospheric magnetic field driven by coronal motions and the standard spiral field are discussed. Copyright 2001 by the American Geophysical Union.