On the Correlation between Geomagnetic Activity and the Diurnal Variation of Cosmic Rays

Abstract

The cosmic ray measurements of K.-G. Malmfors (1949) Oct. 1947—May 1950 have been studied with regard to the effect of geomagnetic activity on the diurnal variation. By means of the same data a study was also made of the secular phase shift first noticed by Elliot and Thambyaphillai (1953). The time of maximum has been found to decrease with increasing values of the international Kp-index, while the amplitude itself increases. These effects were studied for the registration period as a whole as well as for short intervals. The statistical fluctuations are too big for the study of intervals shorter than half a year. The secular phase shift is the same regardless of direction. Also the phase shift accompanying geomagnetic activity is independent of the direction of measurement. This is a good proof that both shifts are due to changes in the original direction of the primaries. It is also shown, that the secular phase shift is independent of the daily geomagnetic disturbances. Apparently two effects exist, both resulting in a change of the direction of the primary cosmic ray particles.