The solar radiation storm intensified rapidly through January 19, reaching S4 \u2013 Severe levels at 18:10 UTC as high-energy proton flux crossed the 10 000 pfu threshold.<\/p>\n
The event is associated with a long-duration X1.9\/3b solar flare that peaked at 18:09 UTC on January 18. The eruption produced Type II and Type IV radio emissions, a 3 200 sfu F10.7 radio burst with a Castelli-U signature, and a full-halo coronal mass ejection observed shortly after the flare peak, indicating an Earth-directed event capable of sustained particle acceleration.<\/p>\n
Proton flux levels began rising late on January 18, initially reaching S1 \u2013 Minor storm levels before escalating through S2 \u2013 Moderate and S3 \u2013 Strong thresholds earlier on January 19. Continued particle injection and efficient shock acceleration drove the event into S4 territory by early evening, confirming a prolonged and energetic solar energetic particle event rather than a short-lived impulsive spike.<\/p>\n
Solar radiation storms reaching S4 \u2013 Severe intensity are very rare. Such events typically occur only a small number of times per 11-year solar cycle, while in weaker cycles they may be entirely absent. Most proton events peak at S1 or S2 levels, with only a limited subset progressing through S3 and into S4, generally in association with the most energetic solar eruptions and fast, Earth-directed CMEs.<\/p>\n
At S4 intensity, significant radiation exposure is possible for passengers and crew on high-latitude, high-altitude flights, and mitigation measures may be required on polar routes. Astronauts conducting extravehicular activities are exposed to unavoidable radiation hazards under these conditions, and EVA operations are typically restricted.<\/p>\n
Satellite systems face increased risk, including memory device upsets, increased noise in imaging systems, and disruptions to star trackers that can affect spacecraft orientation and control. Prolonged exposure to high-energy particles may also result in temporary degradation of solar panel efficiency. Widespread blackout of polar high-frequency radio communications is likely during peak radiation storm conditions.<\/p>\n![\"YouTube](\"https:\/\/i.ytimg.com\/vi\/f505sYVH_04\/hqdefault.jpg\"\/)
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