Rapidly Rising Solar Index is Ahead of Original Forecast

Highlight: Rapidly rising solar index is ahead of original forecast.

Fig. 1: Latest observations, adjusted forecast, previous forecast and upper limit forecast of sunspot number for solar cycle 25.

Discussion: Currently, the sunspot number of solar cycle 25 for May 2022 continues well-ahead of the original forecast (Fig. 1). The original forecast by NASA repeated the relatively weak solar cycle 24 signature. However, the monthly sunspot number has out-performed the original forecast dating back near 2 years. The adjusted forecast implies a solar maximum somewhere in-between the 2000 and 2012 peak solar activity while the upper limit forecast could produce an all-time record strong solar maximum. So far, the increased sunspot activity is not well-correlated with days of geomagnetic storms. The last two years of significant geomagnetic storms were 2003 and 1994. Geomagnetic storms can easily knock-out satellite service to global industry. Of course, the number of satellites compared to near 20 years ago is considerably higher nowadays.

Fig. 2: Annual plot since 1994 identifying number of days with a geomagnetic storm.