Multifractal Detrended Fluctuation Analysis, Cross-Correlation and Clustering of Global 7Be Activity Concentration

Daily [Formula: see text] activity concentrations data across 21 global locations between 2010 and 2017 from the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) were analyzed using multifractal formalism. The multifractal detrended fluctuation analysis revealed that [Formula: see text] distribution across the 21 locations are multifractal ([Formula: see text]) with a wide range of fractal exponents. The observed multifractality was found to be statistically significant except at two locations (RN45 and RN47). The multifractal strength ([Formula: see text]) and Holder’s exponent ([Formula: see text]) were used to group the locations into 3 clusters with K-means algorithm. The relationship between [Formula: see text] and five drivers (Southern Oscillation Index — SOI, North Atlantic Oscillation — NAO, Total Sunspot number — Tot_SN, Northern hemisphere Sunspot number — NH_SN and Southern hemisphere sunspot number — SH_SN) was investigated using multifractal detrended cross-correlation analysis. The multifractal cross-correlation between [Formula: see text] and drivers was found to be 0.06–0.21(SOI), 0.08–0.23 (NAO), 0.04–0.27 (Tot_SN), 0.05–0.25 (NH_SN) and 0.04–0.27 (SH_SN). NAO was found to be the strongest driver of [Formula: see text]. The location, RN16 in Yellowknife Canada, showed strong cross-correlation with the five drivers.