thumbnail

Sunspot random walk and 22-year variation

Geophysical Research Letters

By:
,
DOI: 10.1029/2012GL051818

Links

Abstract

We examine two stochastic models for consistency with observed long-term secular trends in sunspot number and a faint, but semi-persistent, 22-yr signal: (1) a null hypothesis, a simple one-parameter random-walk model of sunspot-number cycle-to-cycle change, and, (2) an alternative hypothesis, a two-parameter random-walk model with an imposed 22-yr alternating amplitude. The observed secular trend in sunspots, seen from solar cycle 5 to 23, would not be an unlikely result of the accumulation of multiple random-walk steps. Statistical tests show that a 22-yr signal can be resolved in historical sunspot data; that is, the probability is low that it would be realized from random data. On the other hand, the 22-yr signal has a small amplitude compared to random variation, and so it has a relatively small effect on sunspot predictions. Many published predictions for cycle 24 sunspots fall within the dispersion of previous cycle-to-cycle sunspot differences. The probability is low that the Sun will, with the accumulation of random steps over the next few cycles, walk down to a Dalton-like minimum. Our models support published interpretations of sunspot secular variation and 22-yr variation resulting from cycle-to-cycle accumulation of dynamo-generated magnetic energy.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Sunspot random walk and 22-year variation
Series title:
Geophysical Research Letters
DOI:
10.1029/2012GL051818
Volume
39
Issue:
10
Year Published:
2012
Language:
English
Publisher:
Wiley
Contributing office(s):
Geologic Hazards Science Center
Description:
L10103; 6 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article