A prediction for the next sunspot cycle

Abstract

A number of predictions for the next sunspot cycle (Cycle 21) are examined and tabulated. It is shown that published predictions, to date, have been predominately in favor of a low sunspot cycle (120 or less). The prediction method of Ohl is discussed. His method is applied, using one hundred and ten years of sunspot and geomagnetic data to give a forecast for Cycle 21. The multiple regression equation developed is shown to be highly significant. The prediction made here specifies a smoothed sunspot maximum of 154, occurring in early 1980. The 95% confidence interval for the prediction is plus or minus 50, and the probability of exceeding 120 is 92.6%. Such a high maximum would be significantly higher and earlier than most previously published predictions. If this forecast is accurate, Cycle 21 will be equivalent to, or greater than, the second largest sunspot cycle observed in the past century. This will have a profound effect on high-frequency communications. Some consequences of such a large cycle are discussed and parallels are drawn to Cycle 18 (maximum of 152). Finally, the latest observed sunspot values are presented to demonstrate the validity of the prediction early in the cycle.