Variability of Cosmic Ray Power Spectra

Variability of the power spectra of cosmic ray temporal profiles in the frequency interval 1.2 × 10-5 Hz (f1) to 1.7 × 10-3 Hz (f2) in the period of two years shows that the integrals of power spectrum density over the interval f1 to 2.8 × 10-4 Hz (P1) are significantly correlated at two neutron monitors differing inacceptance cones and cut-off rigidities. At high frequency region, J>2.8 × 10-4Hz, the integrals P2 are correlated much less. P1 are weakly correlated with the cosmic ray intensity itself. Cross correlation between the time series P1 and the daily averages of geomagnetic indices (Kp, Dst and Ap) is asymmetric, with the maximum shifted to positive time lag. This indicates the stronger relation of the daily averaged geomagnetic indices measured for given day with the P1 obtained a day before, than with the P1 at the same day. The shift is not obtained if cosmic ray intensity, instead of P1, is cross-correlated with geomagnetic indices.