Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Photospheric downflows observed with SDO/HMI, HINODE, and an MHD
  simulation   Downflows on the solar surface are suspected to play a major role in the
dynamics of the convection zone. We investigate the existence of the
long-lasting downflows whose effects influence the interior of the Sun and the
outer layers.
  We study the sets of Dopplergrams and magnetograms observed with SDO and
Hinode spacecrafts and a MHD simulation. All of the aligned sequences, which
were corrected from the satellite motions and tracked with the differential
rotation, were used to detect the long-lasting downflows in the quiet-Sun at
the disc centre. To learn about the structure of the flows below the solar
surface, the time-distance local helioseismology was used.
  The inspection of the 3D data cube (x, y, t) of the 24-hour Doppler sequence
allowed us to detect 13 persistent downflows. Their lifetimes lie in the range
between 3.5 and 20 hours with sizes between 2" and 3" and speeds between -0.25
and -0.72 km/s. These persistent downflows are always filled with the magnetic
field with an amplitude of up to 600 G. The helioseismic inversion allows us to
describe the persistent downflows and compare them to the other
(non-persistent) downflows in the field of view. The persistent downflows seem
to penetrate much deeper and, in the case of a well-formed vortex, the
vorticity keeps its integrity to the depth of about 5 Mm. In the MHD
simulation, only sub-arcsecond downflows are detected with no evidence of a
vortex comparable in size to observations at the surface of the Sun.
  The long temporal sequences from the space-borne allow us to show the
existence of long-persistent downflows together with the magnetic field. They
penetrate inside the Sun but are also connected with the anchoring of coronal
loops in the photosphere, indicating a link between downflows and the coronal
activity. A link suggests that EUV cyclones over the quiet Sun could be an
effective way to heat the corona.

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The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
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The categories of this paper are: cs
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph