Acceleration and Propagation of Solar Energetic Particles
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Solar Energetic Particles (SEPs) are an important component of Space Weather, including radiation hazard to humans and electronic equipment, and the ionisation of the Earth’s atmosphere. We review the key observations of SEPs, our current understanding of their acceleration and transport, and discuss how this knowledge is incorporated within Space Weather forecasting tools. Mechanisms for acceleration during solar flares and at shocks driven by Coronal Mass Ejections (CMEs) are discussed, as well as the timing relationships between signatures of solar eruptive events and the detection of SEPs in interplanetary space. Evidence on how the parameters of SEP events are related to those of the parent solar activity is reviewed and transport effects influencing SEP propagation to near-Earth locations are examined. Finally, the approaches to forecasting Space Weather SEP effects are discussed. We conclude that both flare and CME shock acceleration contribute to Space Weather relevant SEP populations and need to be considered within forecasting tools.
KeywordsSun: particle emission Solar-terrestrial relations Space weather
The authors are grateful to ISSI for organizing the workshop on the scientific foundations of space weather, as well as a number of earlier team meetings that helped us shape our ideas on solar energetic particles. S.D. acknowledges support from the UK Science and Technology Facilities Council (STFC) (grant ST/M00760X/1) and the Leverhulme Trust (grant RPG-2015-094). Research at Paris Observatory received funding from the French space agency CNES and the European Union’s Horizon 2020 research and innovation programme under grant agreement No 637324 (HESPERIA project).
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