Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effects of large-scale non-axisymmetric perturbations in the mean-field
  solar dynamo   We explore a response of a non-linear non-axisymmetric mean-field solar
dynamo model to shallow non-axisymmetric perturbations. After a relaxation
period the amplitude of the non-axisymmetric field depends on the initial
condition, helicity conservation, and the depth of perturbation. It is found
that a perturbation which is anchored at r=0.9R has a profound effect on the
dynamo process, producing a transient magnetic cycle of the axisymmetric
magnetic field, if it is initiated at the growing phase of the cycle. The
non-symmetric with respect to the equator perturbation results in a hemispheric
asymmetry of the magnetic activity. The evolution of the axisymmetric and
non-axisymmetric field depends on the turbulent magnetic Reynolds number R_m.
In the range of R_m=10^{4-6} the evolution returns to the normal course in the
next cycle, in which the non-axisymmetric field is generated due to a
non-linear alpha-effect and magnetic buoyancy. In the stationary state the
large-scale magnetic field demonstrates a phenomenon of "active longitudes"
with cyclic 180 degree "flip-flop" changes of the large-scale magnetic field
orientation. The flip-flop effect is known from observations of solar and
stellar magnetic cycles. However this effect disappears in the model which
includes the meridional circulation pattern determined by helioseismology. The
rotation rate of the non-axisymmetric field components varies during the
relaxation period, and carries important information about the dynamo process.

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The categories of this paper are: math
35
The categories of this paper are: mtrl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
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The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
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The categories of this paper are: hep-ex
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The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: supr-con
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The categories of this paper are: adap-org