S320p.13 — Generation and Properties of Large-Scale Non-axisymmetric Magnetic Fields by Solar Dynamo

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Aug 10th at 6:00 PM until 7:30 PM

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Author(s): Valery Pipin1, Alexander Kosovichev2

Institution(s): 1. Institute for solar-terrestrial physics , 2. New Jersey Institute of Technology

Large-scale non-axisymmetric magnetic fields generated by the solar dynamo, and presumably responsible for the phenomenon of "active longitudes", play an important role in the distribution of solar activity and flares. By calculating 3D mean-field dynamo models, we show that nonlinear coupling between axisymmetric and non-axisymmetric modes, e.g. due to the magnetic feedback on the alpha-effect (see, e.g., [1]), can maintain a large-scale non-axisymmetric dynamo process. Non-axisymmetric random fluctuations of dynamo parameters can be another source for the non-axisymmetric magnetic fields on the Sun. Such fluctuations can provide a mechanism of the magnetic energy transfer from the global field to the non-axisymmetric modes. It is shown that the rotational periods of the non-axisymmetric field correspond to the dynamo process operating in the subsurface shear layer which is located in the range of depths 0.85-0.95R. We find that the magnetic helicity conservation quenches generation of the non-axisymmetric dynamo modes as well as it does for the axisymmetric dynamo. It is concluded that the 3D mean-field non-axisymmetric dynamo models can potentially explain the observed distribution of the solar magnetic activity.
1. Moss, D.,Non-axisymmetric solar magnetic fields, 1999, MNRAS, 306, 300
On 3/18/2015 2:29 PM, Valery Pipin wrote:

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