What Are SEPs?
Solar energetic particles (SEPs) are high-energy protons, electrons, and ions accelerated by solar flares and CME shocks. They can reach Earth in minutes to hours (faster than the CME itself) and pose a radiation hazard for satellites, astronauts, and aviation on polar routes. SEP events are often associated with strong flares and fast CMEs.
Effects
SEPs can cause single-event upsets in satellite electronics, increased radiation dose for crew and passengers, and polar cap absorption (PCA)—ionization in the polar ionosphere that affects radio. Forecasts (e.g. NOAA SWPC) issue radiation storm alerts. Cosmic Radar shows space weather and Kp in the daily report; during strong events, SEP and radiation storm information is available from NOAA SWPC and other official sources.
Sources and further reading
- NOAA – Radiation storms – SEP and S-scale
- NASA – Solar energetic particles – Science and monitoring
- ESA Space Weather – European alerts