Download original image
The maximum annual number of spotless days in each inter-cycle interval vs. maximum annual sunspot number of the following solar cycle. Values for Solar Cycles 1–24 are shown as black plus signs. The solid line is a linear fit to the data and the blue “+” is the prediction that S 25 = 150 based on using a spotless day count of 273 in 2019 in that fit.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.