HR: 0830h
AN: SH21B-0142    [PDF]
TI: Evolution of Large-scale Solar Magnetic Fields in a Flux-Transport Model Including a Multi-cell Meridional Flow
AU: * McDonald, E
EM: mcdonald@hao.ucar.edu
AF: High Altitude Observatory, National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80301 United States
AU: Dikpati, M
EM: dikpati@hao.ucar.edu
AF: High Altitude Observatory, National Center for Atmospheric Research, 3450 Mitchell Lane, Boulder, CO 80301 United States
AB: Advances in helioseismology over the past decade have enabled us to detect subsurface meridional flows in the Sun. Some recent helioseismological analysis (Giles 1999, Haber et al. 2002) has indicated a submerged, reverse flow cell occurring at high latitudes of the Sun's northern hemisphere between 1998 and 2001. Meridional circulation plays an important role in the operation of a class of large-scale solar dynamo, the so-called "flux-transport" dynamo. In such dynamo models, the poleward drift of the large-scale solar magnetic fields and the polar reversal process are explained by the advective-diffusive transport of magnetic flux by a meridional circulation with a poleward surface flow component. Any temporal and spatial variations in the meridional flow pattern are expected to greatly influence the evolution of large-scale magnetic fields in a flux-transport dynamo. The aim of this paper is to explore the implications of a steady, multi-cell flow on the advection of weak, large-scale, magnetic flux. We present a simple, two-cell flux transport model operating in an r-theta cross-section of the northern hemisphere. Azimuthal symmetry is assumed. Performing numerical flux-transport simulations with a reverse flow cell at various latitudes, we demonstrate the effect of this cell on the evolutionary pattern of the large-scale diffuse fields. We also show how a flux concentration may occur at the latitude where the radial flows of the two cells are sinking downward. This work is supported by NASA grants W-19752, W-10107, and W-10175. The National Center for Atmospheric Research is sponsored by the National Science Foundation.
DE: 7524 Magnetic fields
DE: 7536 Solar activity cycle (2162)
DE: 7537 Solar and stellar variability
DE: 7544 Stellar interiors and dynamo theory
SC: SPA - Solar and Heliospheric Physics [SH]
MN: 2003 Fall Meeting