Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: STEREO-A and PROBA2 Quadrature Observations of Reflections of three EUV
  Waves from a Coronal Hole   We investigate the interaction of three consecutive large-scale coronal waves
with a polar coronal hole, simultaneously observed on-disk by the Solar
TErrestrial Relations Observatory (STEREO)-A spacecraft and on the limb by the
PRoject for On-Board Autonomy 2 (PROBA2) spacecraft on January 27, 2011. All
three extreme-ultraviolet(EUV) waves originate from the same active region NOAA
11149 positioned at N30E15 in the STEREO-A field-of-view and on the limb in
PROBA2. We derive for the three primary EUV waves start velocities in the range
of ~310 km/s for the weakest up to ~500 km/s for the strongest event. Each
large-scale wave is reflected at the border of the extended coronal hole at the
southern polar region. The average velocities of the reflected waves are found
to be smaller than the mean velocities of their associated direct waves.
However, the kinematical study also reveals that in each case the end velocity
of the primary wave matches the initial velocity of the reflected wave. In all
three events the primary and reflected waves obey the Huygens-Fresnel
principle, as the incident angle with ~10{\deg} to the normal is of the same
size as the angle of reflection. The correlation between the speed and the
strength of the primary EUV waves, the homologous appearance of both the
primary and the reflected waves, and in particular the EUV wave reflections
themselves implicate that the observed EUV transients are indeed nonlinear
large-amplitude MHD waves.

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The categories of this paper are: hep-ph
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
15
The categories of this paper are: nucl-ex
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol