In January 2020, the students of Earth to Sky Calculus and Spaceweather.com traveled to Abisko, Sweden, to launch a pair of cosmic ray balloons.
Putting all the data together, 2017+2020, they find that radiation has increased +12% in the past 3 years…
The diagram from radiation dose rate (uGy/hr) vs. altitude (feet) shows that atmospheric radiation increases at nearly all altitudes – even in the range where airplanes fly between 25,000 ft and 40,000 ft.
In other words, passengers and flight crews are absorbing ~12% more cosmic radiation than they did only a few years ago.
What’s causing the increase?
It’s solar Solar Minimum, during which the sun’s magnetic field weakens, allowing extra cosmic rays from deep space to penetrate the solar system.
At the moment, the sun is near the bottom of the 11-year solar cycle.
After hitting Earth’s atmosphere, the cosmic rays create a spray of secondary cosmic rays (X-rays and gamma-rays in the energy range 10 keV to 20 MeV) which are measured by the radiation sensors onboard the helium balloons.
Atmospheric radiation increases by 12% in 3 years. And that’s because of the Solar Minimum. Picture by CERN
Scientists from SpaceWeather.com have been launching radiation sensors almost weekly for 5 years.
Data show cosmic rays in the stratosphere have been increasing the entire time.
The new data even show that this increase is not limited to the stratosphere but is also happening at aviation altitudes with a 3-year increase of ~12% even below 40,000 ft.
And all that’s a sign of a deepening Solar Minimum