Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Magnetic Classification of Solar Active Regions 1992 - 2015   The purpose of this letter is to address a blind-spot in our knowledge of
solar active region statistics. To the best of our knowledge there are no
published results showing the variation of the Mount Wilson magnetic
classifications as a function of solar cycle based on modern observations. We
show statistics for all active regions reported in the daily Solar Region
Summary from 1992 January 1 to 2015 December 31. We find that the $\alpha$ and
$\beta$ class active regions (including all sub-groups e.g. $\beta\gamma$,
$\beta\delta$) make up fractions of approximately 20% and 80% of the sample
respectively. This fraction is relatively constant during high levels of
activity, however, an increase in the $\alpha$ fraction to about 35% and and a
decrease in the $\beta$ fraction to about 65% can be seen near each solar
minimum and is statistically significant at the 2-$\sigma$ level. Over 30% of
all active regions observed during the years of solar maxima were appended with
the classifications $\gamma$ and/or $\delta$, while these classifications
account for only a fraction of a percent during the years near the solar
minima. This variation in the active region types indicates that the formation
of complex active regions may be due to the pileup of frequent emergence of
magnetic flux during solar maximum, rather than the emergence of complex,
monolithic flux structures.

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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: q-bio
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The categories of this paper are: cs
2
The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: econ
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The categories of this paper are: alg-geom
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The categories of this paper are: cond-mat