Extracting Hale Cycle Related Components from Cosmic-Ray Data Using Principal Component Analysis

We decompose the monthly cosmic-ray data, using several neutron monitor count rates, of Cycles 19-24 with principal component analysis (PCA). show different cycle limits that first and second PC (CR) data explain 77-79% 13-15% total variation Oulu CR 20-24 (C20- C24), 73-77% 13-17% Hermanus C20-C24, 74-78% 17-21% Climax C19-C22, respectively. The PC1 time series has only one peak in its power spectrum at period 10.95 years, which is average solar for interval SC19-SC24. PC2 same cycles a clear 21.90 (Hale cycle) another 1/3 no period. essential explaining differences intensities even odd CR. have positive phase half negative their PC2. This leads to slow decrease intensity beginning minimum cycles. On contrary, phases are vice versa this faster more rapid recovery cycle. As consequence peak-like structure. exceptions rule 23 24 such former almost zero line PC2, latter similar than earlier These results confirmed skewness-kurtosis (S-K) analysis. Furthermore, S-K shows other cycles, except Cycle 21, on regression correlation coefficient 0.85. 21 all calculated eight stations compactly located S -K coordinate system smaller skewnesses higher kurtoses 23.