Cosmic-ray intensity variations during two solar cycles

Abstract

To facilitate the use of cosmic-ray intensity data from ionization chambers which are being sent to International Geophysical Year World Data Centers, and of those which have appeared in two publications of the Carnegie Institution of Washington, an improved correction for instrumental drift at Huancayo is derived and the reliability of the corrections for seasonal variations is discussed. From ionization chambers, the decrease of intensity from its maxima (near sunspot minima) is shown to lag a year or more behind the increase of solar activity following sunspot minima. This lag does not appear in the results obtained by Neher at high altitude and high latitude, nor in those obtained by Rose from a neutron monitor at Ottawa. The variability of daily means of cosmic-ray intensity (from monthly means) is in 1957 the largest observed during two complete solar cycles. Tables of monthly means corrected for seasonal wave are included, together with graphs of daily means at Huancayo for the period 1954–1957.