dorsal/arxiv
View SchemaA paradigmatic model of Earth's magnetic field reversals
| Authors | F. Stefani, G. Gerbeth, U. Guenther |
|---|---|
| Categories | |
| ArXiv ID | physics/0601011 |
| URL | https://arxiv.org/abs/physics/0601011 |
| Journal | Magnetohydrodynamics 42 (2006) 123-130 |
Abstract
The irregular polarity reversals of the Earth's magnetic field have attracted much interest during the last decades. Despite the fact that recent numerical simulations of the geodynamo have shown nice polarity transitions, the very reason and the basic mechanism of reversals are far from being understood. Using a paradigmatic mean-field dynamo model with a spherically symmetric helical turbulence parameter alpha we attribute the essential features of reversals to the magnetic field dynamics in the vicinity of an exceptional point of the spectrum of the non-selfadjoint dynamo operator. At such exceptional (branch) points of square root type two real eigenvalues coalesce and continue as a complex conjugated pair of eigenvalues. Special focus is laid on the comparison of numerically computed time series with paleomagnetic observations. It is shown that the considered dynamo model with high supercriticality can explain the observed time scale and the asymmetric shape of reversals with a slow decay and a fast field recovery.
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"abstract": "The irregular polarity reversals of the Earth\u0027s magnetic field have attracted\nmuch interest during the last decades. Despite the fact that recent numerical\nsimulations of the geodynamo have shown nice polarity transitions, the very\nreason and the basic mechanism of reversals are far from being understood.\nUsing a paradigmatic mean-field dynamo model with a spherically symmetric\nhelical turbulence parameter alpha we attribute the essential features of\nreversals to the magnetic field dynamics in the vicinity of an exceptional\npoint of the spectrum of the non-selfadjoint dynamo operator. At such\nexceptional (branch) points of square root type two real eigenvalues coalesce\nand continue as a complex conjugated pair of eigenvalues. Special focus is laid\non the comparison of numerically computed time series with paleomagnetic\nobservations. It is shown that the considered dynamo model with high\nsupercriticality can explain the observed time scale and the asymmetric shape\nof reversals with a slow decay and a fast field recovery.",
"arxiv_id": "physics/0601011",
"authors": [
"F. Stefani",
"G. Gerbeth",
"U. Guenther"
],
"categories": [
"physics.geo-ph",
"astro-ph",
"physics.plasm-ph"
],
"journal_ref": "Magnetohydrodynamics 42 (2006) 123-130",
"title": "A paradigmatic model of Earth\u0027s magnetic field reversals",
"url": "https://arxiv.org/abs/physics/0601011"
},
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