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Hydromagnetic dynamos at the low Ekman and magnetic Prandtl numbers
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SYSNO ASEP 0472505 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Hydromagnetic dynamos at the low Ekman and magnetic Prandtl numbers Author(s) Šimkanin, Ján (GFU-E) ORCID, RID Source Title Contributions to Geophysics & Geodesy - ISSN 1335-2806
Roč. 46, č. 3 (2016), s. 221-244Number of pages 24 s. Publication form Online - E Language eng - English Country SK - Slovakia Keywords hydromagnetic dynamo ; magnetic Prandtl number ; inertial forces Subject RIV DE - Earth Magnetism, Geodesy, Geography OECD category Physical geography R&D Projects LG13042 GA MŠMT - Ministry of Education, Youth and Sports (MEYS) Institutional support GFU-E - RVO:67985530 UT WOS 000441852700004 EID SCOPUS 85011596002 DOI https://doi.org/10.1515/congeo-2016-0014 Annotation Hydromagnetic dynamos are numerically investigated at low Prandtl, Ekman and magnetic Prandtl numbers using the PARODY dynamo code. In all the investigated cases, the generated magnetic fields are dominantly-dipolar. Convection is small-scale and columnar, while the magnetic field maintains its large-scale structure. In this study the generated magnetic field never becomes weak in the polar regions, neither at large magnetic Prandtl numbers (when the magnetic diffusion is weak), nor at low magnetic Prandtl numbers (when the magnetic diffusion is strong), which is a completely different situation to that observed in previous studies. As magnetic fields never become weak in the polar regions, then the magnetic field is always regenerated in the tangent cylinder. At both values of the magnetic Prandtl number, strong polar magnetic upwellings and weaker equatorial upwellings are observed. An occurrence of polar magnetic upwellings is coupled with a regenaration of magnetic fields inside the tangent cylinder and then with a not weakened intensity of magnetic fields in the polar regions. These new results indicate that inertia and viscosity are probably negligible at low Ekman numbers. Workplace Geophysical Institute Contact Hana Krejzlíková, kniha@ig.cas.cz, Tel.: 267 103 028 Year of Publishing 2017
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