A prediction for the maximum phase and duration of sunspot cycle 22

Abstract

Based on the modern era sunspot cycles (cycles 10 to present), maximum smoothed sunspot number ( E M ) has followed minimum smoothed sunspot number ( R m ) by approximately 48±6 months, being true for 8 out of the 12 cycles; for 12 out of 12 cycles, R M has followed R m by 48±12 months. Thus for the most reliably known sunspot cycles, ascent (ASC) has always been between 36 and 60 months, displaying a strong clustering between 42 and 54 months. Because of inferred correlative (preferential) behavior between ASC and R M , it may be that ASC for cycle 22 can be better predicted (through the use of an appropriate projected value of R M ). Similarly, because of inferred preferential behavior between maximum amplitude first‐difference and bimodal period class and between even‐ and odd‐cycle numberedness and bimodal period class, it may be that the bimodal period class and length of cycle 22 can also be better predicted. Assuming that it is not a statistical fluke, present indications are that cycle 22, an even‐numbered cycle, will have an R M below that observed for cycle 21. If true, then cycle 22 is a “negative‐valued” maximum amplitude first‐difference cycle, implying that it will have an ASC longer than or equal to 4 years (the median value), although it could be shorter, and that it is a long‐period cycle (having a length longer than 11 years, probably in the range 138±6 months, based on the average length of long‐period cycles during the modern era of sunspot observations). This suggests that cycle 22 will peak sometime in the latter half of 1990 to the first half of 1991 and that it will not end until early to mid 1998.