Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A statistical study of long-term evolution of coronal hole properties as
  observed by SDO   The study of the evolution of coronal holes (CHs) is especially important in
the context of high-speed solar wind streams (HSS) emanating from them. Stream
interaction regions may deliver large amount of energy into the Earths system,
cause geomagnetic storms, and shape interplanetary space. By statistically
analysing 16 long-living CHs observed by the SDO, we focus on coronal,
morphological and underlying photospheric magnetic field characteristics as
well as investigate the evolution of the associated HSSs. We use CATCH to
extract and analyse CHs using observations taken by AIA and HMI. We derive
changes in the CH properties and correlate them to the CH evolution. Further we
analyse the properties of the HSS signatures near 1au from OMNI data by
manually extracting the peak bulk velocity of the solar wind plasma. We find
that the area evolution of CHs mostly shows a rough trend of growing to a
maximum followed by a decay. No correlation of the area evolution to the
evolution of the signed magnetic flux and signed magnetic flux density enclosed
in the projected CH area was found. From this we conclude that the magnetic
flux within the extracted CH boundaries is not the main cause for its area
evolution. We derive CH area change rates (growth and decay) of 14.2 +/- 15.0 *
10^8 km^2/day showing a reasonable anti-correlation (cc =-0.48) to the solar
activity, approximated by the sunspot number. The change rates of the signed
mean magnetic flux density (27.3 +/- 32.2 mG/day) and the signed magnetic flux
(30.3 +/- 31.5 * 10^18 Mx/day) were also found to be dependent on solar
activity (cc =0.50 and cc =0.69 respectively) rather than on the individual CH
evolutions. Further we find that the CH area-to-HSS peak velocity relation is
valid for each CH over its evolution but revealing significant variations in
the slopes of the regression lines.

31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
20
The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
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The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph