Linking cosmic ray intensities to cutoff rigidity through multifractal detrented fluctuation analysis

Abstract

We use multifractal detrented fluctuation analysis (MFDFA) to investigate the relationship between magnetic rigidity or ”cutoff rigidity” and the variability and multifractal behavior in the time series of the cosmic ray flux on Earth, which is detected by neutron monitors on the Earth's surface. Because the cutoff rigidity depends strongly on the geographical latitude of the detectors, not all detectors produce equal cosmic ray counts. Our results indicate that there is some bias in the chaotic nature of the cosmic ray series associated with the latitude of the monitoring stations. We obtain an important relationship between the cutoff rigidity (R) for different behaviors and the Hurst exponent of the series corresponding to the counts at the neutron monitor stations. In particular, an inverse relationship is observed with higher rigidity corresponding to a lower Hurst exponent (H(q=a)=maR+Ba). In particular, for q=−10, considering all time series, the correlation coefficient is approximately 0.80, whereas the R-squared is 0.638, and the coefficients of the linear regression for this case are m=−0.0425±0.006 and b=0.8703±0.025. © 2022 Elsevier B.V.