Cosmic ray intensity pulses

Abstract

Pulse variations in the galactic cosmic ray intensity, extending over intervals of several hours, have often been observed during cosmic ray storms as well as during other periods. On some occasions, these pulses appear in the data recorded at polar stations during epochs characterized by enhanced diurnal anisotropy at low latitudes. The short‐term intensity increase at polar stations cannot be ascribed solely to the azimuthal anisotropy, and it is demonstrated that the cosmic ray transport during a pulse displays both azimuthal and north‐south anisotropies. Furthermore, it is found that the magnitude of the pulse height recorded by a station i is proportional to eμi where μi=cos θi and θi, is the angular separation between the mean asymptotic direction of viewing of station i and the direction of anisotropy in three‐dimensional space. The relationship between pulse modulations and transient disturbances in the interplanetary magnetic field, and especially their location, remain to be investigated.