Remember Cannibal CMEs? Well, Dr. Phillips of Spaceweather has some more:
A SUDDEN DROP IN ATMOSPHERIC RADIATION: Last month, a “Cannibal CME” hit Earth, sparking a strong G3-class geomagnetic storm and auroras as far south as California and New Mexico. You might think such a storm would boost radiation in Earth’s atmosphere. Think again. High-altitude balloons hurriedly launched by Earth to Sky Calculus during the storm on Nov. 3rd and 4th found just the opposite. Radiation in the stratosphere plummeted:
More at the link above. Heliophysics is fun!