SHORT AND LONG-TERM VARIATIONS IN THE COSMIC RAY INTENSITY AND THEIR CONNECTION WITH THE 5303 Å CORONAL LINE INTENSITY IN SOLAR CYCLE No.20

摘要

The cosmic ray modulation in the period 1965÷70 is investigated by the comparison of the intensity data of groundbased stations with different response to primaries. The so-called step-like modulation, already observed by other au¬thors, is found to be produced by the overlapping between the quasi-stationary solar cycle modulation and the Forbush decrease events. Moreover a good correlation between the cosmic-ray variance (Forbush decrease index) and the X5303 coronal intensity at middle heliolatitudes (17.5°÷42.5°) is found, while the quasi-stationary solar cycle modulation is well correlated with the X5303 intensity near the solar equator (0°÷17.5°). The different time behavior of the solar activity at different heliolatitudes causes the step-like modulation.