Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Statistical analysis of acoustic wave power and flows around solar
  active regions   We analyze the effect of a sunspot in its quiet surroundings applying a
helioseismic technique on almost three years of Helioseismic and Magnetic
Imager (HMI) observations obtained during solar cycle 24 to further study the
sunspot structure below the solar surface. The attenuation of acoustic waves
with frequencies lower than 4.2 mHz depends more strongly on the wave direction
at a distance of $6^o-7^o$ from the sunspot center. The amplification of higher
frequency waves is highest 6$^o$ away from the active region and it is largely
independent of the wave's direction. We observe a mean clockwise flow around
active regions, which angular speed decreases exponentially with distance and
has a coefficient close to $-0.7$ degree$^{-1}$. The observed horizontal flow
in the direction of the nearby active region agrees with a large-scale
circulation around the sunspot in the shape of cylindrical shell. The center of
the shell seems to be centered around 7$^o$ from the sunspot center, where we
observe an inflow close to the surface down to $\sim$2 Mm, followed by an
outflow at deeper layers until at least 7 Mm.

24
The categories of this paper are: dg-ga
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
36
The categories of this paper are: cmp-lg