Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Long-term Variations in the Intensity of Plages and Networks as Observed
  in Kodaikanal Ca-K Digitized Data   In our previous article (Priyal et al. in Solar Phys. 289, 127, 2014) we have
discussed the details of observations and methodology adopted to analyze the
Ca-K spectroheliograms obtained at the Kodaikanal Observatory (KO) to study the
variation of Ca-K plage areas, enhanced network (EN), and active network (AN)
for Solar Cycles, namely 19, 20, and 21. Now, we have derived the areas of
chromospheric features using KO Ca-K spectroheliograms to study the long-term
variations of Solar Cycles 14 to 21. The comparison of the derived plage areas
from the data obtained at the KO observatory for the period 1906-1985 with that
of MWO, NSO for the period 1965-2002, earlier measurements made by Tlatov,
Pevtsov, and Singh (Solar Phys. 255, 239, 2009) for KO data, and the SIDC
sunspot numbers shows a good correlation. The uniformity of the data obtained
with the same instrument remaining with the same specifications provided a
unique opportunity to study long-term intensity variations in plages and
network regions. Therefore, we have investigated the variation of the intensity
contrast of these features with time at a temporal resolution of six months
assuming that the quiet-background chromosphere remains unchanged during the
period 1906-2005 and found that the average intensity of the AN, representing
the changes in small-scale activity over solar surface, varies with solar cycle
being less during the minimum phase. In addition, the average intensity of
plages and EN varies with a very long period having a maximum value during
Solar Cycle 19, which was the strongest solar cycle of twentieth century.

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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: cs
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The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: econ
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The categories of this paper are: math
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The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph
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The categories of this paper are: gr-qc