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Session 33 - Dynamics of Solar Magnetic Fields.
Oral session, Tuesday, June 11
Wisconsin Center,

[33.03] Dynamics of Solar Magnetic Fields: Theoretical Aspects

A. A. van Ballegooijen (Center for Astrophysics)

The distribution of magnetic fields on the solar surface is determined by processes of flux emergence, transport and cancellation. Magnetic flux emerges in the form of bipoles of various size, strength and orientation. Large and medium-sized active regions emerge in two activity belts on either side of the equator, and generally have orientations in accordance with Hale's polarity law. Smaller ephemeral regions have a broader latitude distribution and a more random orientation. Weak intranetwork fields are seen to emerge in the centers of supergranules everywhere on the Sun. The emerged field interacts with convective flows on a variety of spatial and temporal scales, creating a continually evolving pattern of small-scale flux concentrations and causing the magnetic elements to perform a random walk across the solar surface. Chance encounters of opposite polarity elements can lead to flux cancellation, i.e. disappearance of magnetic flux from the photosphere. In this talk I review recent developments in the theory and modelling of these physical processes. The emphasis is on the structure and dynamics of magnetic fields in the photosphere and below. I conclude with a list of key scientific questions to be addressed by future research.

Program listing for Tuesday