Polar coronal holes and cosmic-ray modulation

Science. 1980 Feb 15;207(4432):761-3. doi: 10.1126/science.207.4432.761.

Abstract

A comparison of the size of polar coronal holes with the cosmic-ray intensity observed during the most recent sunspot cycle shows close correspondence. This lends support to recent suggestions that the well-known sunspot-cycle modulation of cosmic rays is a three-dimensional effect, probably related to the global character of the interplanetary magnetic field.