Figure 5

Sunspot Cycle 25 amplitude forecast in context. The monthly mean sunspot number since 1749. The data values are represented by dots and the 12-month running average values are illustrated as a dark gray shaded area. The sunspot cycle numbers are shown in the shaded area—SC1 starting in the 1755 and SC24 presently drawing to a close. For comparison with Figure 1 we show the (M2019) vertical blue dashed lines that signify the magnetic cycle termination times that trigger the rapid growth of sunspot activity, while the vertical orange dashed lines show the discrete Hilbert transform derived terminators of Leamon et al. (2020), see Figure 3 and Table 1. Also shown are the forecast values of SC25 amplitude from the analysis above (purple dot) and the SC25PP (green dot). The horizontal light-gray shared region is to place the present forecast in historical context. Finally, we show the hindcast sunspot maxima for each cycle (red dots) derived from the measured terminator values and using the relationship developed above - the error bars on the hindcast dots represent the 68% confidence value.