Sunspot random walk and 22-year variation
Geophysical Research Letters
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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.
| 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 |
| Larger Work Title | Geophysical Research Letters |
| Google Analytic Metrics | Metrics page |