HESPERIA has unfolded both the physical processes resulting into high-energy SEP events and also built novel forecasting operational services in order to enhance the performance of solar radiation storm prediction. SEP events pose important challenges for modern society, largely relying on technology. They have effects both on technological systems and on human health. They can cause Single Event Upsets, solar cell degradation, interference with CCD imaging devices, star tracking positioning problems, and increased space radiation for space missions. High-energy SEPs may have easier access to the polar regions near Earth’s magnetic poles than at the equator, thus, high inclination LEO satellites can at times be vulnerable to SEPs, and the International Space Station (ISS). SEP events can also affect signal propagation between the Earth and satellites due to polar cap absorption events resulting from intense ionization of the polar ionosphere. When SEPs reach aviation altitudes they can be a serious hazard for human health, since the radiation dose received can increase significantly, particularly during high-latitude flights and polar routes. For commercial aviation this can be a risk for frequent flyers and aircrew. >30 MeV protons can be a fatal radiation hazard for astronauts. Overall objectives are: 1) To develop two novel SEP forecasting schemes based upon proven concepts, 2) To develop SEP forecasting tools searching for electromagnetic proxies of the γ-ray emission in order to predict large SEP events, 3) To perform systematic exploitation of the novel high-energy γ-ray observations of the FERMI mission together with in situ SEP measurements near 1 AU, 4) To provide for the first time publicly available software to invert neutron monitor (ΝΜ) observations of relativistic SEPs to physical parameters that can be compared with the space-borne measurements at lower energies, 5) To perform examination of currently unexploited tools, 6) To design recommendations for future SEP forecasting systems . Two novel real-time SEP forecasting systems have been developed, HESPERIA REleASE generating proton flux alerts at 30-50 MeV, making use of SOHO/EPHIN relativistic electrons and ACE/EPAM near-relativistic electrons and HESPERIA UMASEP-500 which makes real-time predictions of the occurrence of GLE events, from the analysis of soft X-ray and differential proton flux measured by the GOES satellites. The latter is the only GLE predictor with a performance exceeding that of the NM based ones. A unique GLE inversion software was developed to derive the solar source function and the interplanetary transport parameters of relativistic SEPs observed near Earth. The extensive data analysis of 25 high-energy γ-ray events detected by Fermi/LAT showed that the SEP events associated with long-duration γ-ray emission are remarkable, often widespread, but not unique in terms of SEP characteristics. It was found that there is no evidence for time-extended electron acceleration in the low corona, close to the flaring active region, after the early post-impulsive phase. Comparison of the statistical characteristics of the solar cycles 23 (SC23) and 24 (SC24) showed the total number of SEP events is about 1/3 lower in SC24 compared to SC23, for both low and high energies. Using a joint Ne/O and Fe/O data analysis correction of the interplanetary transport effect was carried out and the Fe-poor and Fe-rich large SEP events were identified and compared in both cycles.
