In November 2025, Earth was hit by a rare and powerful geomagnetic storm. The United Kingdom found itself at its epicenter, and scientists there sought to study it using an extensive network of neutron detectors. The findings have now been published, raising questions about how well we really understand space weather.
Radiation Exceeds Recommended Thresholds at High Altitudes
The most comprehensive dataset ever collected from Earth’s atmosphere during a solar radiation event has highlighted the importance of better coordination in radiation monitoring for aviation safety, according to a new study led by the University of Surrey. As phys.org reports, the study, published in Space Weather, analyzed data collected on November 11, 2025, during the largest ground-level enhancement (GLE) recorded in nearly 20 years. The event was triggered by a rare X5-class solar flare, which sent an intense stream of energetic particles from the Sun into Earth’s atmosphere, reaching ground level.
Researchers combined readings from ground-based neutron monitors across the United Kingdom, detectors aboard transatlantic passenger flights, and radiation monitors carried to high altitudes by weather balloons launched from the United Kingdom and the Netherlands.
The study showed that radiation levels above the United Kingdom varied considerably with location and altitude. Weather balloons launched in collaboration with the Met Office from its station in Lerwick, in the Shetland Islands, recorded radiation levels above the International Civil Aviation Organization’s (ICAO) recommended “moderate” threshold at business-jet altitudes—higher than those used by commercial airliners—several hours after the storm’s peak. At even greater altitudes, corresponding to supersonic flight, measurements exceeded ICAO’s “severe” threshold.
The Importance of Direct Atmospheric Observations and International Cooperation
Scientists were able to observe the event in real time. They began receiving alerts from neutron monitors around the world indicating that something unusual might be happening, and launched weather balloons within minutes.
“We were watching live measurements come in from balloons, aircraft, and ground-based sensors as the storm unfolded. Having all these systems operating together during the largest ground-level enhancement recorded in nearly 20 years gave us an exceptionally rare dataset and the most complete picture of this type of event we have ever had,” said Ben Clewer, a research fellow and developer of space weather models and systems.
The study emphasizes the importance of combining direct atmospheric observations with the forecasting models currently used to assess aviation radiation risks during powerful solar flares. Existing international advisory systems rely largely on model outputs based on observations from the ground and space.
Observations Surprised Scientists
“The first balloon launch from Lerwick recorded an extraordinary radiation environment high in the atmosphere. This shows how geographically variable these events can be, and why coordinated monitoring systems are so important for improving our understanding of radiation risks to aviation,” said Dr. Fraser Baird, a co-author of the study and research fellow at the Surrey Space Centre.
The project involved researchers from the Met Office and the Royal Netherlands Meteorological Institute (KNMI)—both partners in launching weather balloons for space weather monitoring—as well as Lancaster University and other international partners.
Improving the Ability to Forecast Aviation Risks
The findings could help improve atmospheric radiation monitoring in the future, particularly as airlines increasingly rely on sensitive electronic systems and most flights follow high-latitude routes, where radiation exposure is greatest.
The data collected during this event, both from ground-based monitors and balloon launches, are vital to understanding how space weather affects radiation levels throughout Earth’s atmosphere. This is the first time radiation data have been collected through the atmosphere during a space weather event in this way. It represents a major advance in scientific understanding and will improve our ability to forecast space weather.
The study also marks the first time the United Kingdom has been able to monitor a major solar radiation storm using a national network of neutron monitors stretching from Cornwall to the Shetland Islands. Researchers say that just ten years ago, Britain had no operational sensors of this kind.
