The famous extreme solar and particle event of 20 January 2005 is analyzed from two perspectives. Firstly, using multi-spectral data, we study temporal, spectral, and spatial features of the main phase of the flare, when the strongest emissions from microwaves up to 200 MeV gamma-rays were observed. Secondly, we relate our results to a long-standing controversy on the origin of solar energetic particles (SEP) arriving at Earth, i.e., acceleration in flares, or shocks ahead of coronal mass ejections (CMEs). Our analysis shows that all electromagnetic emissions from microwaves up to 2.22 MeV line gamma-rays during the main flare phase originated within a compact structure located just above sunspot umbrae. In particular, a huge (≈ 10 5 sfu) radio burst with a high frequency maximum at 30 GHz was observed, indicating the presence of a large number of energetic electrons in very strong magnetic fields. Thus, protons and electrons responsible for various flare emissions during its main phase were accelerated within the magnetic field of the active region. The leading, impulsive parts of the ground-level enhancement (GLE), and highest-energy gamma-rays identified with π 0 -decay emission, are similar and closely correspond in time. The origin of the π 0 -decay gamma-rays is argued to be the same as that of lower-energy emissions, although this is not proven. On the other hand, we estimate the sky-plane speed of the CME S.N. Kuznetsov deceased 17 May 2007. 150 V.V. Grechnev et al.to be 2 000 -2 600 km s −1 , i.e., high, but of the same order as preceding non-GLE-related CMEs from the same active region. Hence, the flare itself rather than the CME appears to determine the extreme nature of this event. We therefore conclude that the acceleration, at least, to sub-relativistic energies, of electrons and protons, responsible for both the major flare emissions and the leading spike of SEP/GLE by 07 UT, are likely to have occurred nearly simultaneously within the flare region. However, our analysis does not rule out a probable contribution from particles accelerated in the CME-driven shock for the leading GLE spike, which seemed to dominate at later stages of the SEP event.

The solar cosmic ray event associated with an X7.1 class solar flare on 20 January 2005 was one of the greatest enhancements ever recorded by the ground level worldwide network of neutron monitors. The event occurred during a Forbush decrease, almost at the end of the 23rd cycle of solar activity. In this work a ground level enhancement model for getting the broadest possible picture, as well as for understanding the physics of solar cosmic ray particles under extreme solar conditions, is proposed. Neutron monitors responses from 41 stations widely distributed around the Earth have been modeled to an anisotropic solar proton flux, using an optimization method based on the Levenberg‐Marquardt algorithm. The parameters of the primary solar particles outside the magnetosphere and their dynamics, as well as the characteristics of solar cosmic rays during this event are obtained and discussed.

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A high-time resolution Neutron Monitor Database (NMDB) has started to be realized in the frame of the Seventh Framework Programme\ud of the European Commission. This database will include cosmic ray data from at least 18 neutron monitors distributed around\ud the world and operated in real-time. The implementation of the NMDB will provide the opportunity for several research applicationsmost of which will be realized in real-time mode. An important one will be the establishment of an Alert signal when dangerous solar\ud cosmic ray particles are heading to the Earth, resulting into ground level enhancements effects registered by neutron monitors. Furthermore,\ud on the basis of these events analysis, the mapping of all ground level enhancement features in near real-time mode will provide an\ud overall picture of these phenomena and will be used as an input for the calculation of the ionization of the atmosphere. The latter will beuseful together with other contributions to radiation dose calculations within the atmosphere at several altitudes and will reveal the\ud absorbed doses during flights. Moreover, special algorithms for anisotropy and pitch angle distribution of solar cosmic rays, which have\ud been developed over the years, will also be set online offering the advantage to give information about the conditions of the interplanetary\ud space. All of the applications will serve the needs of the modern world which relies at space environment and will use the extensivenetwork of neutron monitors as a multi-directional spectrographic detector. On top of which, the decreases of the cosmic ray intensity –\ud known as Forbush decreases – will also be analyzed and a number of important parameters such as galactic cosmic ray anisotropy will be\ud made available to the users of NMDB. A part of the NMDB project is also dedicated to the creation of a public outreach website with the scope to inform about cosmic rays and their possible effects on humans, technological systems and space-terrestrial environment. Therefore, NMDB will also stand as an informative gate on space research through neutron monitor's data usage.\ud © 2010 COSPAR. Published by Elsevier Ltd. All rights reserved