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Session 33 - Dynamics of Solar Magnetic Fields.
Oral session, Tuesday, June 11
A new paradigm is emerging concerning the formation, evolution, and influence of solar magnetic features. It had long been pictured that magnetic flux emerged with a simple potential magnetic field structure, evolved by coalescing pores, and then finally disintegrated and dispersed in to the surrounding photosphere. If a sunspot region displayed 'whorls' or magnetic shear, the shear was thought to be brought on by the turbulent surface motions, and subsequently released during flares.
In the past five years it has become necessary to dismiss this simple picture. Building on early observations of sunspot helicity, erupting prominences and flaring active regions, and on cartoon ideas of twisted flux tubes, there is recent strong observational support for a new paradigm. The notions of simple potential Ømega-loops of magnetic flux and shearing surface flows are giving way to the idea that non-potential magnetic flux is systematically generated in the solar interior and transported to the surface where we see it as current-carrying sunspot groups, non-force-free magnetic fields, helical filament structures and self-reversed magnetic clouds. Indeed, the picture of magnetic fields being confined only to large easily observable features such as plage fields, sunspots, and filaments has been shifted to a view that magnetic flux is pervasive, and abundant on small size scales. The new paradigm is coherent, but of course some gaps in the old picture are replaced with new puzzles. There is, of course, scatter and disagreement amongst the observational results. The cause of the systematic helicities is now below an easily observable regime. And the simple notion of flux dispersion now must make room for helicity conservation, flux expulsion into the solar atmosphere, and the conflicting results concerning magnetic field reconfiguration in the context of solar flares. I will review the puzzle and show how the new view of the magnetic sun has evolved. I will outline the key new observational results as well as highlight missing pieces; and I'll review how, with the orchestra of ground-based and space-based instruments, we are in an unprecedented position to both fill some of the gaps and rigorously test this new paradigm of solar physics.
Program listing for Tuesday