Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multi-height Scattering Phase Shifts From Sunspots And Phase Differences
  Between Photospheric Heights With SDO/HMI and AIA Data   Following Couvidat (2013), we analyze data from the Helioseismic and Magnetic
Imager (HMI) and the Atmospheric Imaging Assembly (AIA) instruments onboard the
Solar Dynamics Observatory: Doppler velocity and continuum intensity at 6173 A
as well as intensity maps at 1600 A and 1700 A. Datasets of 14 active regions
and four quiet-Sun regions are studied at four heights in the solar
photosphere. An Hankel-Fourier analysis is performed around these regions of
interest. Outgoing-ingoing scattering phase shifts at a given atmospheric
height are computed, as well as ingoing-ingoing and outgoing-outgoing phase
differences between two atmospheric heights. The outgoing-ingoing phase shifts
produced by sunspots show little dependence on measurement height, unlike the
acoustic power reduction measured in Couvidat (2013). Phenomena happening above
continuum level, like acoustic glories, appear not to have a significant effect
on the phases. However there is a strong dependence on sunspot size,
line-of-sight magnetic flux, and intensity contrast. As previously suggested by
other groups, the region of wave scattering appears both horizontally smaller
and vertically less extended than the region of acoustic power suppression, and
occurs closer to the surface. Results presented here should help refine
theoretical models of acoustic wave scattering by magnetic fields.
Ingoing-ingoing phase differences between two measurement heights are also
computed and show a complex pattern highly dependent on atmospheric height. In
particular, a significant sensitivity of AIA signals to lower chromospheric
layers is shown. Finally, ingoing-ingoing minus outgoing-outgoing phase
differences between various measurement heights are discussed.

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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: stat
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The categories of this paper are: hep-th
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The categories of this paper are: ao-sci
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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: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: gr-qc