Real-time prediction of the occurrence of GLE events

A tool for predicting the occurrence of Ground Level Enhancement (GLE) events using the UMASEP scheme is presented. This real-time tool, called HESPERIA UMASEP-500, is based on the detection of the magnetic connection, along which protons arrive in the near-Earth environment, by estimating the lag correlation between the time derivatives of 1 min soft X-ray flux (SXR) and 1 min near-Earth proton fluxes observed by the GOES satellites. Unlike current GLE warning systems, this tool can predict GLE events before the detection by any neutron monitor (NM) station. The prediction performance measured for the period from 1986 to 2016 is presented for two consecutive periods, because of their notable difference in performance. For the 2000-2016 period, this prediction tool obtained a probability of detection (POD) of 53.8% (7 of 13 GLE events), a false alarm ratio (FAR) of 30.0%, and average warning times (AWT) of 8 min with respect to the first NM station's alert and 15 min to the GLE Alert Plus's warning. We have tested the model by replacing the GOES proton data with SOHO/EPHIN proton data, and the results are similar in terms of POD, FAR, and AWT for the same period. The paper also presents a comparison with a GLE warning system. Plain Language Summary Extreme solar events may accelerate solar particles to near the speed of light reaching the Earth in a few minutes. These particles may interact with the Earth's atmosphere to produce penetrating neutrons known as Ground Level Enhancements (GLEs) which are detected by neutron monitors worldwide. These particles may irradiate astronauts in space and passengers and flight crews in commercial aircraft flying at extreme polar latitudes. A recent research and development activity led by Prof. Marlon Nunez from the University of Malaga (Spain) and funded by the H2020 European research program developed the first model that is able to predict these events. This research activity concluded that this system is able to predict nearly a half of these events. This predictor, called HESPERIA UMASEP-500, processes real-time solar X-rays and protons measured by the GOES satellites. Before the development of this system, space weather systems have been warning users about evolving GLE events by processing neutron measurements recorded on ground level. The new prediction system provides valuable added 8-15 min of advance warning of GLE events to system operators to make necessary adjustments to vulnerable spacecraft operations and components which may prevent the loss of valuable space assets.