Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the nature of the in-ecliptic interplanetary magnetic field's
  two-humped distribution at 1AU   It was found out that the distribution's shape of the in-ecliptic (as well as
radial) component of the interplanetary magnetic field (IMF) significantly
changes with the heliocentric distance, which poorly corresponds to classical
models of the solar wind and the interplanetary magnetic field (IMF) expansion.
For example, distributions of the radial photospheric and the source surface's
magnetic field in the ecliptic plane are Gaussian-like, the distribution of the
radial IMF component at the Earth orbit demonstrates two-humped shape, and it
becomes again Gaussian-like at 3-4 AU. These differences lead to lack of
correspondence between simulations of the IMF behaviour at 1 AU and
observations. Our results indicate that picture of the IMF expansion into space
is more complicated than usually considered, and the sector structure is not
the only source of the two-humped shape of the in-ecliptic or radial IMF
component. We have analysed data from different spacecraft at the distances
from 0.29 AU to 4 AU and found that the shape of the radial IMF component
distribution strongly depends on a heliocentric distance and a heliolatitude.
The "two-humped IMF" effect is most brightly expressed at low heliolatitudes at
0.7-2 AU, but it fully disappears at 3-4 AU. There is also dependence of the
IMF distributions' view on a solar cycle due to active processes, such as solar
flares and CMEs. We suppose that the in-ecliptic solar wind field at 1 AU is
influenced by solar active regions in a high degree, and actually the
distribution is the three-humped: two humps correspond to the IMF from the
middle and high heliolatitudes and the third one is the theoretically expected
distribution from the solar field nearby the heliomagnetic equator. Vanishing
of the IMF zero-component with the distance from the Sun partially could be a
result of a magnetic reconnection at the current sheets in the solar wind.

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The categories of this paper are: cs
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The categories of this paper are: econ
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The categories of this paper are: adap-org
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: eess
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-th
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The categories of this paper are: solv-int
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The categories of this paper are: math
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: hep-ph
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The categories of this paper are: math-ph
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The categories of this paper are: hep-th
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The categories of this paper are: gr-qc