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| Paper: |
Flux–Transport Dynamo with Strong Surface Diffusivity |
| Volume: |
454, The 3rd Hinode Science Meeting |
| Page: |
23 |
| Authors: |
Hotta, H.; Yokoyama, T. |
| Abstract: |
The flux-transport dynamo model for the solar sunspot cycle is
revised and is demonstrated by using the axisymmetric kinematic simulations.
The flux-transport dynamo has succeeded to explain the general cyclic behaviors
of the sunspots especially in the gradual shift of the sunspot toward the equator
and the poleward migration of the surface magnetic field. It has been known,
however, that previous models failed to avoid the strong polar surface field and
the strong toroidal field at the base in the high latitude, both of which are not
consistent with observations. With an additional intense diffusivity profile near
the surface two problematic features can be avoided. The surface poloidal field
generated by the α effect is transported down to the base of the
convection zone
not by the meridional flow but by the surface diffusion mainly in the mid-latitude.
This prevents the concentration of the polar surface field and the amplification
of the toroidal field at the high latitude. The condition to obtain the proper
magnetic field strength near the pole is ηsurf / u0 > 2 × 109 cm, where ηsurf and
u0 are the surface diffusivity and the meridional flow speed, respectively. We
also do some parameter studies to ensure the importance of the surface strong
diffusivity. |
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