Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Making Sense of Sunspot Decay II: Deviations from the Mean Law and Plage
  Effects   In a statistical analysis of Debrecen Photoheliographic Results sunspot area
data we find that the logarithmic deviation (log D)' of the area decay rate D
from the parabolic mean decay law (derived in the first paper in this series)
follows a Gaussian probability distribution. As a consequence, the actual decay
rate D and the its time average are also characterized by approximately
lognormal distributions, as found in an earlier work. The correlation time of
(log D)' is about 3 days. We find a significant physical anticorrelation
between (log D)' and the amount of plage magnetic flux of the same polarity in
an annulus around the spot on Kitt Peak magnetograms. The anticorrelation is
interpreted in terms of a generalization of the turbulent erosion model of
sunspot decay to the case when the flux tube is embedded in a preexisting
homogeneous "plage" field. The decay rate is found to depend inversely on the
value of this plage field, the relation being very close to logarithmic, i.e.
the plage field acts as multiplicative noise in the decay process. A Gaussian
probability distribution of the field strength in the surrounding plage will
then naturally lead to a lognormal distribution of the decay rates, as
observed. It is thus suggested that, beside other multiplicative noise sources,
the environmental effect of surrounding plage fields is a major factor in the
origin of lognormally distributed large random deviations from the mean law in
the sunspot decay rates.

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The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
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The categories of this paper are: acc-phys
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: q-fin
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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
3
The categories of this paper are: physics