A 22-year cycle in sunspot activity
Abstract
Recently, using the new group sunspot number series introduced by Hoyt and Schatten, we have shown that the weak sunspot activity during the Maunder minimum is modulated by a 22-year periodicity. Here we demonstrate that, after subtracting the long-term trend due to the Gleissberg cycle and after averaging the 11-year cyclicity, the group sunspot series depicts a 22-year cycle with an amplitude of about 10% of the current sunspot activity level. The well known Gnevyshev-Ohl rule is a reflection of such a persistent 22-year periodicity. We discuss the origin of the 22-year cycle in sunspot activity in terms of a weak relic solar magnetic field.
- Publication:
-
IAU Joint Discussion
- Pub Date:
- 2000
- Bibcode:
- 2000IAUJD...7E..28U