Fig. 3

Superposed epoch analysis. Left side Aa index values for cycles 11–24 in composites of 40 days from the full Moon. Right side Aa index values for cycles 20–23 in composites of 40 days from the full Moon. Figures a and b correspond to whole cycles, c and d to the ascending phase, and e and f to the descending phase. The black circles represent the new Moon on the 15th day of the 40-day period. The white circles represent the full Moon at the 30th day of the 40-day period. The horizontal dashed lines correspond to one standard deviation taking the 40-day period; the values for each panel are: a 0.32, b 0.20, c 0.25, d 0.11, e 0.24, and f 0.18