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E. McDonald, M. Dikpati (HAO NCAR)
Over the past decade, helioseismology has enabled us to detect meridional flows beneath the surface of the sun. Recently, some helioseismic analysis has indicated that submerged, reverse meridional flow cells sometimes develop at higher latitudes (Giles 1999, Haber et al. 2002). Meridional circulation plays important roles in large-scale solar dynamos of the flux-transport type. In this class of dynamos, magnetic flux is primarily advected by meridional circulation. Variations in the meridional flow patterns should impact the evolution of the sun's large-scale magnetic fields. We show, by invoking a flux-transport model, that a reverse flow cell at higher latitudes provides a good mechanism for keeping the polar field from becoming too concentrated. We also show that a flux concentration happens due to a strong downward flow at the boundary between the primary and reverse cells. It may cause a sudden change in the sound speed as noted by Antia, Chitre, and Thompson (2000). We also present the effect of long-term variations of the flow on the evolution of large-scale fields on the century time-scale. This work is supported by NASA grants W-10107 and W-10175. The National Center for Atmospheric Research is sponsored by the National Science Foundation.
The author(s) of this abstract have provided an email address for comments about the abstract: mcdonald@hao.ucar.edu
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Bulletin of the American Astronomical Society, 36 #2
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