Open Access
Research Article

Fig. 2

image

Download original image

Plot of the values taken by the Ca index between 1995 and 2018 included (black thin line). The training (green area), validation (yellow area), and test (red area) sets are highlighted. The 13-month smoothed Sunspot Number is also plotted as an indicator for the solar cycle (red thick line).

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.