Recalculated Sunspot Cycle Characteristics Using the New Sunspot Number Series

Abstract:

The new sunspot number series introduces a number of changes, including dropping the multiplicative factor of ~0.6 that was previously used to bring the numbers into agreement with those obtained by Rudolf Wolf with his small telescope in the mid-19^th century. Using the new numbers clearly requires changing the functional relationships between sunspot number and other solar activity indices (e.g. sunspot area, 10.7 cm radio flux, total solar irradiance, x-ray flares, and geomagnetic activity). We find that, in most cases, these relationships exhibit less scatter with the new numbers. Solar cycle prediction methods must also be recalibrated with the new numbers. The new numbers clearly indicate the need for a reassessment of the impact of solar variability on terrestrial climate. There is now no appearance of a significant secular rise in solar activity levels since the early 18^th century, suggesting, that earlier estimates of the impact of solar activity on climate should be revised downward.