# 77th ground level enhancement of 11 Nov 2025 measured by UK neutron monitors, radiosondes and two flights

- Published: 2026-11-12 03:53 UTC
- Section: Sky & Space › Space
- Tags: 77th ground level enhancement, 11 November 2025 solar storm, radiosonde radiation measurements, neutron monitors UK, ICAO radiation thresholds, aircraft radiation dose, supersonic altitude radiation, Space Weather journal
- URL: https://realtech.media/news/rt-fd659af6c8c02aa9c4897ce7_77th_ground_level/

**Data from the 11 November 2025 solar particle event show strong regional differences. At supersonic altitudes the ICAO severe radiation threshold was exceeded twofold.**

![77th ground level enhancement of 11 Nov 2025 measured by UK neutron monitors, radiosondes and two flights](https://realtech.media/media/2026/11/446ebd4ecaf5c804.png)
*wtftime.ru*

On 11 November 2025, at about 10:20 UTC, the 77th Ground Level Enhancement (GLE) occurred, a rise in radiation at the surface caused by solar particles. A paper in Space Weather presents data from neutron monitors across the United Kingdom, radiation sensors on radiosondes launched in the UK and the Netherlands, and dosimeters on two transatlantic flights from London Heathrow to New York [1].

## Neutron monitors and radiosondes

The ground-level observations show strong anisotropy in the intensity and time profile of the event across the UK. A strong peak was recorded in the north at the beginning of the event, and a second, weaker peak appeared in the south about one hour later [1].

Radiosondes launched from the northern extremity of the UK showed that the ICAO moderate radiation threshold was exceeded at business jet altitudes several hours after the event peak. At supersonic altitudes the ICAO severe threshold was exceeded by a factor of two [1]. Radiosondes launched from the south of the UK and from the Netherlands did not show a significant increase in radiation levels [1]. According to the University of Surrey team as summarised in press coverage, the first balloon with a radiation sensor went up from the Shetland Islands about an hour after the event began.

## Transatlantic flights

The Heathrow–New York (JFK) flight, which departed at 11:45 UTC, recorded a 42.6% increase in total ambient dose equivalent exposure compared with typical background conditions. No ICAO thresholds were exceeded on this flight [1]. The second flight, Heathrow–Newark, departing at 17:45 UTC, showed no significant increase in radiation exposure [1].

Press coverage of the work reports that no aviation warnings about elevated radiation were issued during the event. It also says that modelling run at the time indicated the moderate threshold would be exceeded for no more than 10 minutes, while measurements showed a more serious situation. The researchers propose an international network of radiosondes with radiation sensors to monitor solar storms and to alert crews on flight routes.

## Sources

1. [Space Weather](https://doi.org/10.1029/2026SW005279)
2. [wtftime.ru](https://wtftime.ru/space/170557/moschnejshaja-solnechnaja-burja-za-20-let-okazalas-silnee-prognozov-no-my-uznali-ob-etom-tolko-cherez-god)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-fd659af6c8c02aa9c4897ce7_77th_ground_level/