By applying Principal Component Analysis (PCA)  to the low-resolution full disk magnetograms captured in cycles 21-23 by the Wilcox Solar Observatory, Zharkova et al., (2012, MNRAS) discovered not one but two principal components of this solar background magnetic field  (see Fig. 1, top plot) associated with two magnetic waves marked by red and blue lines.  The authors … Continue reading Grand solar cycle and minimum