Polar regions activity and the prediction of the height of the solar cycle 25

TL;DR

This paper suggests that polar regions activity measurements indicate that solar cycle 25 may be higher than previously predicted, challenging earlier low activity forecasts based on sunspot numbers.

Contribution

It introduces a new approach using polar regions activity, related to coronal holes, to predict the height of solar cycle 25, providing a potentially more accurate forecast.

Findings

Polar regions activity was higher before SC25 than before SC24.

The height of SC25 could be higher than the low predictions based on sunspot numbers.

Polar activity measurements may improve solar cycle predictions.

Abstract

The forthcoming solar cycle (SC) 25 was beleived to be rather low when using the sunspot number (SN) as a measurement of the level of activity. The most popular prediction was made by the panel of NASA in 2019, including works based on extrapolations of dynamo-type models. We however discovered that using different observations to measure the level of polar regions activity several years before the start of SC25 and also after the start of the SC25 in 2020, the height of the SC25 could be high. The polar regions activity we considered seems related to the polar coronal holes (CH) activity and it is found significantly higher before the SC25 that it was before the SC24 and accordingly, we suggest that the SN cycle could indeed be much higher than during the SC24 that was a low SN height cycle.