The sunspot cycle influence on the solar and lunar daily geomagnetic variations

Abstract

The relative importance of the sunspot cycle influence on solar and lunar daily geomagnetic variations has been discussed for over a century, but hitherto inconclusively. The problem is re-examined using results from a number of new analyses of data obtained during the IGY/C and the preceding sunspot minimum, as well as results from analyses of longer series of data. Particular attention is paid to the significance of the results. It is shown that the sunspot cycle influence on the lunar variations, measured by the Wolf ratio, is significant, but is only about one third of the sunspot cycle influence on the solar variations. This appears, with moderate spread, in all elements, in all non-polar latitudes, and for different sunspot cycles.