This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: The most comprehensive data set ever collected from Earth's atmosphere during a solar radiation event has highlighted the importance of better-coordinated radiation monitoring for aviation safety, according to new research led by the University of Surrey. The study, published in Space Weather, analyzed data collected on Nov. 11, 2025, during the largest ground level enhancement (GLE) observed in almost 20 years.
Triggered by a rare X5-class solar flare, the event caused an intense burst of radiation particles from the sun to penetrate Earth's atmosphere and reach ground level. Researchers combined readings from ground-based neutron monitors across the U.K., detectors on board transatlantic passenger flights and radiation monitors carried by weather balloons launched high into the atmosphere from the U.K. and the Netherlands. The findings showed that radiation levels above the U.K. varied significantly depending on location and altitude.
Weather balloons launched in collaboration with the Met Office from its site in Lerwick, Shetland, recorded radiation levels above the International Civil Aviation Organizations (ICAO) "moderate" advisory threshold at business jet altitudes (higher than commercial jet altitudes) several hours after the storm peaked. At still-higher altitudes associated with supersonic flight, measurements exceeded the ICAO "severe" threshold. One flight from London to New York that departed during the storm also experienced a 46% increase in radiation exposure compared to normal background conditions.
"For me, the most exciting moment was watching the event unfold in real time. We started getting alerts from neutron monitors around the world suggesting something unusual might be happening and, within minutes, the balloon launches were triggered. "We were then watching measurements come back live from the balloons, aircraft and ground sensors as the storm developed.
Having all those systems operating together during the largest observed ground level enhancement in almost 20 years gave us an incredibly rare data set and the most complete picture we've ever had of this type of event," said Ben Clewer, research fellow and space weather model and system developer. The study emphasizes the importance of combining direct atmospheric observations with the forecasting models currently used to assess aviation radiation risk during extreme solar radiation events. Current international advisory systems mostly rely on model outputs informed by ground- and space-based observations.
"I'd spent years studying these events, so when the alerts first came through, I assumed it would just be another small blip. But when I logged into the data stream and saw what was happening over Lerwick, I genuinely couldn't believe it. "The first balloon launch from Lerwick recorded an extraordinary radiation environment high in the atmosphere.
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