The Newly Calibrated sunspot Group Number over the last 400 years

A graph showing the sunspot Group Number as measured over the past 400 years after to the new calibration. The Maunder Minimum, between 1645 and 1715, when sunspots were scarce and the winters harsh is clearly visible.

The modulations of the 11-year solar cycle is clearly seen, as well as the 70–100-year Gleissberg cycle.

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