Free Access

Fig. 4


Long-term variation in daily average intensities of the He i and O v spectral lines. The solid lines and their associated error bars represent the mean and the standard deviation of the average intensity values over 90-day time intervals before (grey) and after (black) applying the Del Zanna et al. correction factors. The vertical dashed-lines indicate the two one-year time spans chosen to cover the solar activity minima.

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.