Solar Flare and Magnetic Storm Effects in Cosmic-Ray Intensity near the Geomagnetic N Pole

Abstract

During the solar flare of July 25, 1946 an increase of 14 percent in hourly mean values of cosmic-ray ionization was observed at Thule, Greenland (geomagnetic latitude 88°N) at sea level, under 11 cm Pb. The increase and its gradual diminution toward normal during the 24 hours after the flare was statistically indistinguishable from results at Godhavn, Greenland (geomagnetic latitude 80°N). The subsequent decrease during the magnetic storm, which began 27 hours after the flare, was also in agreement at Thule and Godhavn. If the increase were due to charged particles from the sun, these observations at Thule emphasize the fact that the trajectories involved are markedly affected by factors other than the earth's magnetic dipole.