Small Ground-Level Enhancement of 6 January 2014: Acceleration by CME-Driven Shock?статья
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Дата последнего поиска статьи во внешних источниках: 17 мая 2016 г.
Аннотация:Abstract. Available spectral data for solar energetic particles (SEPs) measured near the
Earth’s orbit (GOES-13) and on the terrestrial surface (polar neutron monitors) on 6 January
2014 are analyzed. A feature of this solar proton event (SPE) and weak ground-level enhancement
(GLE) is that the source was located behind the limb. For the purpose of comparison,
we also use the Advanced Composition Explorer (ACE) data on sub-relativistic electrons
and GOES-13 measurements of a strong and extended proton event on 8 – 9 January
2014. It was found that the surface observations at energies >433 MeV and GOES-13 data
at >30 –>700 MeV may be satisfactorily reconciled by a power-law time-of-maximum
(TOM) spectrum with a characteristic exponential tail (cutoff). Some methodological difficulties
of spectrum determination are discussed. Assuming that the TOM spectrum near the
Earth is a proxy of the spectrum of accelerated particles in the source, we critically consider
the possibility of shock acceleration to relativistic energies in the solar corona. Finally, it is
suggested to interpret the observational features of this GLE under the assumption that small
GLEs may be produced by shocks driven by coronal mass ejections. However, the serious
limitations of such an approach to the problem of the SCR spectrum prevent drawing firm
conclusions in this controversial field.