On the lognormality of historical magnetic-storm intensity statistics: Implications for extreme-event probabilities
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Abstract
An examination is made of the hypothesis that the statistics of magnetic storm maximum intensities are the realization of a lognormal stochastic process. Weighted least squares and maximum likelihood methods are used to fit lognormal functions to −Dst storm time maxima for years 1957–2012; bootstrap analysis is used to established confidence limits on forecasts. Both methods provide fits that are reasonably consistent with the data; both methods also provide fits that are superior to those that can be made with a power‐law function. In general, the maximum likelihood method provides forecasts having tighter confidence intervals than those provided by weighted least squares. From extrapolation of maximum likelihood fits: a magnetic storm with intensity exceeding that of the 1859 Carrington event, −Dst ≥ 850 nT, occurs about 1.13 times per century and a wide 95% confidence interval of [0.42, 2.41] times per century; a 100 year magnetic storm is identified as having a −Dst ≥ 880 nT (greater than Carrington) but a wide 95% confidence interval of [490, 1187] nT.
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | On the lognormality of historical magnetic-storm intensity statistics: Implications for extreme-event probabilities |
| Series title | Geophysical Research Letters |
| DOI | 10.1002/2015GL064842 |
| Volume | 42 |
| Issue | 16 |
| Publication Date | August 19, 2015 |
| Year Published | 2015 |
| Language | English |
| Publisher | American Geophysical Union |
| Publisher location | Washington, D.C. |
| Contributing office(s) | Geologic Hazards Science Center |
| Description | 10 p. |
| First page | 6544 |
| Last page | 6553 |
| Online Only (Y/N) | N |
| Additional Online Files (Y/N) | N |