Cosmic-ray cutoffs at high latitude

Abstract

The measurements of many spectrums of solar protons at northern latitudes have shown that the cutoffs are commonly much lower than those calculated for the earth's magnetic field as deduced from surface measurements, together with any reasonable ring current. We show that most of the observations can be reasonably accounted for with a magnetic field which, in addition to the contributions mentioned, has a turbulent component everywhere beyond a certain distance from the center of the earth. The model is essentially that explored by Parker and by Rothwell. The fact that the solar wind distorts the field at great distances must, as Akasofu et al. suggested, produce a modification, the nature of which we flare is probably the one that began at 1257 UT on this date.