Predicting solar energetic proton events (E > 10 MeV)

Abstract

[1] A high level of proton radiation exposure can be dangerous to astronauts, satellite equipment, and air passengers/crew flying along polar routes. The presented solar energetic proton (SEP) event forecaster is based on a dual-model approach for predicting the time interval within which the integral proton flux is expected to meet or surpass the Space Weather Prediction Center threshold of J (E > 10 MeV) = 10 pr cm −2 sr −1 s −1 and the intensity of the first hours of well-and poorly connected SEP events. This forecaster analyzes flare and near-Earth space environment data (soft X-ray, differential and integral proton fluxes). The purpose of the first model is to identify precursors of well-connected events by empirically estimating the magnetic connectivity from the associated CME/flare process zone to the near-Earth environment and identifying the flare temporally associated with the phenomenon. The goal of the second model is to identify precursors of poorly connected events by using a regression model that checks whether the differential proton flux behavior is similar to that in the beginning phases of previous historically poorly connected SEP events and thus deduce similar consequences. An additional module applies a higherlevel analysis for inferring additional information about the situation by filtering out inconsistent preliminary forecasts and estimating the intensity of the first hours of the predicted SEP events. The highlevel module periodically retrieves solar data and, in the case of well-connected events, automatically identifies the associated flare and active region. For the events of solar cycles 22 and 23 of the NOAA/ SWPC SEP list, the presented dual-model system, called UMASEP, has a probability of detection of all well-and poorly connected events of 80.72% (134/166) and a false alarm rate of 33.99% (69/203), which outperforms current automatic forecasters in predicting >10 MeV SEP events. The presented forecaster has an average warning time of 5 h 10 min for the successfully predicted events, 1 h 5 min for wellconnected events and 8 h 28 min for poorly connected events, with a maximum warning time of 24 h for very gradual SEP events.

Solar flares, coronal mass ejections and solar energetic particle event characteristics

“…This is evident for forecasting systems of SEP events that rely either on remote-sensing observations of the Sun (Laurenza et al 2009;Núñez 2011;Papaioannou et al 2015) or on in situ measurements (Posner 2007). In particular, the achieved warning time at a subset of common SEP events between the technique furnished by Laurenza et al (2009) and the concept of Posner (2007) has shown that the former leads to a median warning time of 55 min and the latter of 50 min in advance of the National Oceanic and Atmospheric Administration (NOAA) event threshold crossing (10 pfu at >10 MeV).…”

“…Given that the complexity of the underlying physical processes of the acceleration and propagation of SEP events is still a very active research area, the prognosis of SEP event occurrence and their corresponding characteristics (e.g., peak flux, duration, fluence) mostly relies on near real-time observations of SFs and CMEs and makes use of the aforementioned empirical relations (Smart & Shea 1989;Balch 1999;Garcia 2004aGarcia , 2004bLaurenza et al 2009;Núñez 2011;Papaioannou et al 2015). In addition, the work from Posner (2007) has proven the concept of short-term forecasting of the appearance and intensity of solar ion events by means of relativistic electrons, making use of the higher speed of these electrons propagating from the Sun to 1 AU.…”

Solar Energetic Particles and Space Weather: Science and Applications

“…Earth-Moon-Mars Radiation Environment Module (EMMREM) (Schwadron 2010), Predictions of radiation from REleASE, EMMREM and Data Incorporating CRaTER, COSTEP and other SEP measurements (PREDICCS) (Schwadron 2012), Solar Energetic Particle MODel (SEPMOD) (Luhmann et al 2010), SOLar Particle ENgineering Code (SOLPENCO) (Aran et al 2006), and SOLPENCO2 (provides SEP modelling away from 1 AU to the SEP statistical model of the SEPEM project (Crosby et al 2015))) (b) Empirical models (e.g. University of Malaga Solar Energetic Particle (UMASEP) system (Núñez 2011), Relativistic Electron Alert System for Exploration (REleASE) (Posner 2007), Proton Prediction System (PPS) , PROTONS system (Balch 2008), GLE Alert Plus (Kuwabara et al 2006;Souvatzoglou et al 2014) and Laurenza's approach (Laurenza et al 2009)) In some cases forecasting systems rely on methods from both categories such as the SEPForecast tool built under the EU FP7 COMESEP project (263252) (Crosby et al 2012), (http://www.comesep.eu/alert/).…”

HESPERIA Forecasting Tools: Real-Time and Post-Event

“…However, we attempted a proofof-concept by using historical SEP events. The UMASEP forecasting scheme (Núñez 2011(Núñez , 2015 uses the positive time derivative of the observed SXR flux as an indicator of energy release at the Sun. The SXR burst shows the heating of the corona during a flare.…”

“…In this chapter the two novel real-time SEP forecasting tools developed and operating within the HESPERIA project are presented, based on the University of MAlaga Solar particle Event Predictor (UMASEP) (Núñez 2011(Núñez , 2015 and Relativistic Electron Alert System for Exploration (REleASE) schemes (Posner 2007).…”