Magnetostrophic MRI in the earth's outer core
We show that a simple, modified version of the Magnetorotational Instability (MRI) can develop in the outer liquid core of the Earth, in the presence of a background shear. It requires either thermal wind, or a primary instability, such as convection, to drive a weak differential rotation within the...
| मुख्य लेखकों: | , , |
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| स्वरूप: | Journal article |
| भाषा: | English |
| प्रकाशित: |
2008
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| _version_ | 1826301782586818560 |
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| author | Petitdemange, L Dormy, E Balbus, S |
| author_facet | Petitdemange, L Dormy, E Balbus, S |
| author_sort | Petitdemange, L |
| collection | OXFORD |
| description | We show that a simple, modified version of the Magnetorotational Instability (MRI) can develop in the outer liquid core of the Earth, in the presence of a background shear. It requires either thermal wind, or a primary instability, such as convection, to drive a weak differential rotation within the core. The force balance in the Earth's core is very unlike classical astrophysical applications of the MRI (such as gaseous disks around stars). Here, the weak differential rotation in the Earth core yields an instability by its constructive interaction with the planet's much larger rotation rate. The resulting destabilising mechanism is just strong enough to counteract stabilizing resistive effects, and produce growth on geophysically interesting timescales. We give a simple physical explanation of the instability, and show that it relies on a force balance appropriat to the Earth's core, known as magnetostrophic balance. Copyright 2008 by the American Geophysical Union. |
| first_indexed | 2024-03-07T05:37:34Z |
| format | Journal article |
| id | oxford-uuid:e46f8ec5-4b84-47e2-b185-d618cd26f3d8 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T05:37:34Z |
| publishDate | 2008 |
| record_format | dspace |
| spelling | oxford-uuid:e46f8ec5-4b84-47e2-b185-d618cd26f3d82022-03-27T10:16:39ZMagnetostrophic MRI in the earth's outer coreJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:e46f8ec5-4b84-47e2-b185-d618cd26f3d8EnglishSymplectic Elements at Oxford2008Petitdemange, LDormy, EBalbus, SWe show that a simple, modified version of the Magnetorotational Instability (MRI) can develop in the outer liquid core of the Earth, in the presence of a background shear. It requires either thermal wind, or a primary instability, such as convection, to drive a weak differential rotation within the core. The force balance in the Earth's core is very unlike classical astrophysical applications of the MRI (such as gaseous disks around stars). Here, the weak differential rotation in the Earth core yields an instability by its constructive interaction with the planet's much larger rotation rate. The resulting destabilising mechanism is just strong enough to counteract stabilizing resistive effects, and produce growth on geophysically interesting timescales. We give a simple physical explanation of the instability, and show that it relies on a force balance appropriat to the Earth's core, known as magnetostrophic balance. Copyright 2008 by the American Geophysical Union. |
| spellingShingle | Petitdemange, L Dormy, E Balbus, S Magnetostrophic MRI in the earth's outer core |
| title | Magnetostrophic MRI in the earth's outer core |
| title_full | Magnetostrophic MRI in the earth's outer core |
| title_fullStr | Magnetostrophic MRI in the earth's outer core |
| title_full_unstemmed | Magnetostrophic MRI in the earth's outer core |
| title_short | Magnetostrophic MRI in the earth's outer core |
| title_sort | magnetostrophic mri in the earth s outer core |
| work_keys_str_mv | AT petitdemangel magnetostrophicmriintheearthsoutercore AT dormye magnetostrophicmriintheearthsoutercore AT balbuss magnetostrophicmriintheearthsoutercore |