09.01.2014 - 13:57 [ National Oceanic and Atmospheric Administration (N.O.A.A.) ]

Solar Cycle 23 Project: Summary of Panel Findings

(08.November 1996) The general trend in recent solar activity cycles (Figure 1) is toward larger amplitude sunspot cycles; Cycle 19 was the largest in recorded history (smoothed sunspot number maximum of 201 in March, 1958), and Cycle 22 was the third largest (smoothed maximum of 159 in July, 1989). Cycles 21 and 22 both showed annual averages of geomagnetic activity that were large in comparison with most cycles in the record of aa indices (Figure 2). The dramatic variability from one cycle to the next in these sunspot and geomagnetic records shows the difficulty in making empirical predictions of both types of activity. The issue is further complicated by the lack of a successful quantitative, theoretical model of the Sun‘s magnetic cycle.