Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observations of Asymmetries in Ionospheric Return Flow During Different
  Levels of Geomagnetic Activity   It is known that the magnetic field of the Earth's closed magnetosphere can
be highly displaced from the quiet-day configuration when interacting with the
interplanetary magnetic field (IMF), an asymmetry largely controlled by the
dawn-dusk component of the IMF. The corresponding ionospheric convection has
revealed that footprints in one hemisphere tend to move faster to reduce the
displacement, a process we refer to as the restoring of symmetry. Although the
influence on the return flow convection from the process of restoring symmetry
has been shown to be strongly controlled by the IMF, the influence from
internal magnetospheric processes has been less investigated. We use 14 years
of line-of-sight measurements of the ionospheric plasma convection from the
Super Dual Auroral Radar Network to produce high-latitude convection maps
sorted by season, IMF, and geomagnetic activity. We find that the restoring
symmetry flows dominate the average convection pattern in the nightside
ionosphere during low levels of magnetotail activity. For increasing
magnetotail activity, signatures of the restoring symmetry process become less
and less pronounced in the global average convection maps. We suggest that tail
reconnection acts to reduce the asymmetric state of the closed magnetosphere by
removing the asymmetric pressure distribution in the tail set up by the IMF
$\mathit{B}_{y}$ interaction. During active periods the nightside magnetosphere
will therefore reach a more symmetric configuration on a global scale. These
results are relevant for better understanding the dynamics of flux tubes in the
asymmetric geospace, which is the most common state of the system.

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The categories of this paper are: alg-geom
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The categories of this paper are: econ
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The categories of this paper are: q-alg
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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: math
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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph