Forbush decrease

It occurs due to the magnetic field of the plasma solar wind sweeping some of the galactic cosmic rays away from Earth.

Over the following several days, the galactic cosmic ray intensity returns to normal.

Forbush decreases have also been observed by humans on Mir and the International Space Station (ISS), at other locations in the inner heliosphere such as the Solar Orbiter spacecraft,[2] and at Mars with the Mars Science Laboratory rover's Radiation assessment detector[3] and the MAVEN orbiter,[4] as well as in the outer solar system by instruments onboard Pioneer 10 and 11 and Voyager 1 and 2, even past the orbit of Neptune.

It is more difficult to shield astronauts from galactic cosmic rays than from solar wind, so future astronauts might benefit most from radiation shielding during solar minima, when the suppressive effect of CMEs is less frequent.

A 2009 peer-reviewed article[6] found that low clouds contain less liquid water following Forbush decreases, and for the most influential events the liquid water in the oceanic atmosphere can diminish by as much as 7%.