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Session 101 - The Sun.
Display session, Thursday, January 18
North Banquet Hall, Convention Center

[101.10] Meridional Flow, Torsional Oscillations and Random Walk of Photospheric Magnetic Features

H. B. Snodgrass (Lewis and Clark College), S. B. Dailey (U. Wisconsin)

We have used two-dimensional cross-correlations of Mount Wilson coarse-array magnetograms, spaced at 24-38 days, to determine the pattern of meridional drifts for photospheric features in the large-scale background field during the period 1967-1993. The flow pattern is linked to the butterfly diagram, and varies markedly during the activity cycle. The dominant trend is motion away from regions of high flux concentration. Our results are consistent with a picture in which magnetic features of size comparable to a few supergranules behave like 'particles' undergoing a Brownian motion on the solar surface. They appear neither to be tightly bound to subsurface field structures, nor to evaporate, and the diffusion that appears to propel them about evidently does not extend to small enough scales to take them apart. Comparison with the magnetic torsional oscillation suggests that the torsional pattern is an artifact of the meridional drift pattern rather than an actual East-West flow. \end abstract

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