Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relationship between the Magnetic Flux of Solar Eruptions and the Ap
  Index of Geomagnetic Storms   Solar coronal mass ejections (CMEs) are main drivers of the most powerful
non-recurrent geomagnetic storms. In the extreme-ultraviolet range, CMEs are
accompanied by bright post-eruption arcades and dark dimmings. The analysis of
events of the Solar Cycle 23 (Chertok et al., 2013, Solar Phys. 282, 175)
revealed that the summarized unsigned magnetic flux in the arcades and dimming
regions at the photospheric level, $\Phi$, is significantly related to the
intensity (Dst index) of geomagnetic storms. This provides the basis for the
earliest diagnosis of geoefficiency of solar eruptions. In the present article,
using the same data set, we find that a noticeable correlation exists also
between the eruptive magnetic flux, $\Phi$, and another geomagnetic index, Ap.
As the magnetic flux increases from tens to $\approx 500$ (in units of
$10^{20}$ Mx), the geomagnetic storm intensity measured by the 3-hour Ap index,
enhances in average from Ap $\approx 50$ to a formally maximum value of 400 (in
units of 2 nT). The established relationship shows that in fact the real value
of the Ap index is not limited and during the most severe magnetic storms may
significantly exceed 400.

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The categories of this paper are: eess
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-alg
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The categories of this paper are: acc-phys
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The categories of this paper are: comp-gas
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The categories of this paper are: nlin
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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci
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The categories of this paper are: gr-qc
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
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The categories of this paper are: dg-ga