Low- and high-frequency spectral behavior of cosmic-ray intensity for the period 1953–1996

Abstract

Abstract.A study of the cosmic-ray intensity power spectrum using the Climax Neutron Monitor data in the frequency range from 10 −9 Hz to 10 −7 Hz (which corresponds to periodicities from 11 years to a few months) during the period 1953-1996, was carried out by means of the successive approximations method of analysis and was compared against the power spectrum and the maximum entropy methods. The contributions of the time evolution of several peaks to the global one were obtained. Except for the well-known 11-year and the 1-year variations, peaks at 7.7, 5.5, 2 and 1.7 years are found. Several peaks with periods less than 10 months have appeared in our analysis, while the occurrence of 5.1 months is obtained in all the examined solar cycles with a strong signature in cycle 21. Transitions of these quasiperiodicities are seen in power spectra plots. Some of them can be attributed to the modulation of the cosmic ray intensity by solar activity. Others are sporadic and have been previously attributed to the interplanetary magnetic field. The results obtained support once again the argument regarding the difference in the solar activity between odd and even solar cycles.

Rotation of the Earth, solar activity and cosmic ray intensity

“…6a show that the phase lag between SSN and CRI is large for odd solar cycles and negligible or even negative for even solar cycles. This result confirms results by previous authors (Nymmik and Suslov, 1995;Usoskin et al, 2001;Gupta et al, 2006;Mishra et al, 2006;and Mavromichalaki et al, 2007). Although a negative phase lag for solar cycle 20 (see Fig.…”

“…But since the Sun can influence the interplanetary space and the Earth, even by different mechanisms, the dominating frequencies observed in solar, interplanetary and Earth parameters can be very similar. For example, some periods in SA discussed by Hathaway (2010), and observed by Mavromichalaki et al (2003) and Kudela et al (2010) in CRI, are similar to the ones observed in LOD.…”

“…For SA and CRI, values of phase lags and of cycle length are clearly different for even and odd solar cycles. More precisely, being equal to about 10 months or slightly less on average over about four-five last solar cycles, the phase lag is relatively large (about 15-20 months) for odd solar cycles and relatively small (less than 10 months) or even negative for even solar cycles (Nymmik and Suslov, 1995;Usoskin et al, 2001;Gupta et al, 2006;Mishra and Gupta, 2006;Mavromichalaki et al, 1997Mavromichalaki et al, , 2007Paouris et al, 2012;Thomas et al, 2013). We thus propose that an investigation of phase lags between SA, CRI and LOD could help explain the apparent correlation (causal or fortuitous) between SA and LOD.…”

Variability of Low Energy Cosmic Rays Near Earth

“…Results about quasi-periodicity ~150 days in CR measured on the ground can be found e.g. in papers (Mavromichalaki et al, 2003;Kudela et al, 2010).…”

“…Figure 5 presents a brief summary of CR quasi-periodicities obtained in long time of measurements by NM. Figure 5 were reporteded by (Mavromichalaki et al, 2003) in the analysis of the data until 1996. For detailed analysis and for identification of contribution of various quasi-peridicities in the signal over the long time, the wavelet transform technique is suitable to be used in future, along with analysis of data from NMs at different geomagnetic cut-off positions and from muon telescopes sensitive to higher energies.…”