AAS 200th meeting, Albuquerque, NM, June 2002
Session 89. Solar Internal Structure and Dynamics
Oral, Thursday, June 6, 2002, 2:00-3:30pm, Mesilla

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[89.07] Effects Of Turbulent Pumping In Flux-transport Dynamos

M. Dikpati (HAO/NCAR), A. A. van Ballegooijen (SAO)

Motivated by recent findings that the interaction of a magnetic sheet with stratified convection induces a strong tendency for pumping the magnetic fields downward (Dorch & Nordlund 2001, A&A, 365, 562), we explore the implications of such downward transport of magnetic field using a kinematic, flux-transport dynamo. We formulate the pumping effect by prescribing it as a flow field in addition to differential rotation and meridional circulation in such a way as to conserve the mass. The primary aim of such study is to investigate whether in the presence of such downward pumping the Babcock-Leighton flux-transport dynamo can withstand the parity selection issue. It has recently been shown that the formation of an elongated equatorial dipole is necessary for coupling N&S hemispheres through the antisymmetric magnetic field about the equator (Dikpati & Gilman 2001, ApJ, 559, 428), as inferred from Hale's polarity observation. Poloidal fields generated in a Babcock-Leighton model fail to do so because they undergo large decay during their long traversal to reach the equator at the shear layer. Present study indicates that the inclusion of a strong downward pumping (~10 m/s) in a Babcock-Leighton flux-transport dynamo can indeed provide additional downward speed for the transport of flux for forming the extended dipole at the base of the convection zone and hence, regain the solar-like mode-symmetry. This work has been supported by NASA grants W-19752 and S-10145-X.

The author(s) of this abstract have provided an email address for comments about the abstract: dikpati@hao.ucar.edu

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.