Forecasting and analysis of solar particle radiation storms: A state-of-the-art solution provided by the HESPERIA SEP Real-Time Forecasting products
Authors: Malandraki Olga , Karavolos Michalis , Kokkinis Dimitris , Milas Nikolaos , Crosby Norma , Dierckxsens Mark , Nunez Marlon , Kuehl Patrick 
Published: February 2023

For human spaceflight beyond low-Earth orbit, particularly outside the Earth's magnetosphere, it is essential to provide accurate predictions of Solar Energetic Particle (SEP) occurrences. SEPs with energies ranging from tens of keV to a few GeV, are a significant component in the description of the space environment. SEP events feature a wide range of energy spectrum profiles and can last for a few hours to several days or even weeks. As well as posing a threat to modern technology that heavily relies on spacecraft and posing a major radiation hazard to astronauts, they can also constitute a threat to avionics and commercial aircraft in extreme circumstances. The SEP Real-Time Forecasting HESPERIA products have been developed under the HESPERIA H2020 project (Project Coordinator: Dr. Olga Malandraki) and since 2015 provide significant results concerning the prediction of SEP events. More specifically, the HESPERIA UMASEP-500 product makes real-time predictions of the occurrence of >500 MeV proton events and Ground Level Enhancement (GLE) events based on the analysis of soft X-ray and high energy differential proton fluxes measured by the GOES satellite network. The HESPERIA REleASE product, based on the Relativistic Electron Alert System for Exploration (REleASE) forecasting scheme, generates real-time predictions of the proton flux (30-50 MeV) at L1, making use of relativistic and near-relativistic electron measurements by the SOHO/EPHIN and ACE/EPAM experiments, respectively. Lastly, the HESPERIA REleASE Alert is a notification system based on the forecasts produced by the HESPERIA REleASE product and informs about the expected radiation impact in real-time using an illustration and a distribution system for registered users. The real-time and highly accurate forecasts as well as the timely performance offered by the HESPERIA products have attracted the attention of various space organizations (e.g. NASA/CCMC, SRAG) and also led to the selection and integration of them into the ESA Space Weather (SWE) Service Network (https://swe.ssa.esa.int/noa-hesperia-federated). The integration process, based on the strict guidelines posed by ESA, has determined the current form of the HESPERIA products using state-of-the-art technologies and paradigms concerning both the graphical user interface and the mechanisms to provide the forecasting results to the end users with a high-quality experience. We will present the HESPERIA products as provided through the ESA SWE Service Network under the Space Radiation Expert Service Centre (R-ESC). Moreover, solar radiation storms successfully predicted during Solar cycle 25 will also be presented and discussed. (Work performed in the frame of ESA Space Safety Programme&#8217;s network of space weather service development and pre-operational activities and supported under ESA Contract 4000134036/21/D/MRP).