Diurnal Variation of Cosmic Ray Intensity at Different Group of Geomagnetic Index (Ap)

The solar modulation of Galactic Cosmic Rays (GCR) is revealed in the record of neutron monitors in terms of daily variation. Day-to-day and long term basis daily variations have been investigated for the recent period from 1965 to 2015 along with geomagnetic disruption index Ap on twelve-monthly average basis. Here Ap index has been used as a placeholder for the solar bring on interplanetary disturbances. It is create that, in general on an annual average basis, both the diurnal amplitude as well as the diurnal phase is considerably lower in the years of low Ap values, through the period 1965 to 2015. Such as a result was also informed for the earlier periods. However, anomalous and determined results for the diurnal variations have been received when the daily values of Ap are diffused in five groups with the first group demonstrating low Ap condition (i.e. quite periods) and the last group naturally representing the disturbed conditions.