Chemical Convection and Stratification in the Earth's Outer Core
Convection in the Earth's outer core is driven by buoyancy sources of both thermal and compositional origin. The thermal and compositional molecular diffusivities differ by several orders of magnitude, which can affect the dynamics in various ways. So far, the large majority of numerical simula...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2019-05-01
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| Series: | Frontiers in Earth Science |
| Subjects: | |
| Online Access: | https://www.frontiersin.org/article/10.3389/feart.2019.00099/full |
| _version_ | 1818152110422753280 |
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| author | Mathieu Bouffard Gaël Choblet Stéphane Labrosse Johannes Wicht |
| author_facet | Mathieu Bouffard Gaël Choblet Stéphane Labrosse Johannes Wicht |
| author_sort | Mathieu Bouffard |
| collection | DOAJ |
| description | Convection in the Earth's outer core is driven by buoyancy sources of both thermal and compositional origin. The thermal and compositional molecular diffusivities differ by several orders of magnitude, which can affect the dynamics in various ways. So far, the large majority of numerical simulations have been performed within the codensity framework that consists in combining temperature and composition, assuming artificially enhanced diffusivities for both variables. In this study, we use a particle-in-cell method implemented in a 3D dynamo code to conduct a first qualitative exploration of pure compositional convection in a rotating spherical shell. We focus on the end-member case of infinite Schmidt number by totally neglecting the compositional diffusivity. We show that compositional convection has a very rich physics that deserves several more focused and quantitative studies. We also report, for the first time in numerical simulations, the self-consistent formation of a chemically stratified layer at the top of the shell caused by the accumulation of chemical plumes and blobs emitted at the bottom boundary. When applied to likely numbers for the Earth's core, some (possibly simplistic) physical considerations suggest that a stratified layer formed in such a scenario would be probably weakly stratified and may be compatible with magnetic observations. |
| first_indexed | 2024-12-11T13:49:31Z |
| format | Article |
| id | doaj.art-cbb6c86770674d939d6d47b90648099e |
| institution | Directory Open Access Journal |
| issn | 2296-6463 |
| language | English |
| last_indexed | 2024-12-11T13:49:31Z |
| publishDate | 2019-05-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Earth Science |
| spelling | doaj.art-cbb6c86770674d939d6d47b90648099e2022-12-22T01:04:21ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632019-05-01710.3389/feart.2019.00099414052Chemical Convection and Stratification in the Earth's Outer CoreMathieu Bouffard0Gaël Choblet1Stéphane Labrosse2Johannes Wicht3Department Planets and Comets, Max Planck Institute for Solar System Research, Göttingen, GermanyLaboratoire de Planétologie et Géodynamique, Université de Nantes, Nantes, FranceLaboratoire de Géologie de Lyon, Université de Lyon, École Normale Supérieure de Lyon, Université Lyon-1, CNRS, UMR 5276, Lyon, FranceDepartment Planets and Comets, Max Planck Institute for Solar System Research, Göttingen, GermanyConvection in the Earth's outer core is driven by buoyancy sources of both thermal and compositional origin. The thermal and compositional molecular diffusivities differ by several orders of magnitude, which can affect the dynamics in various ways. So far, the large majority of numerical simulations have been performed within the codensity framework that consists in combining temperature and composition, assuming artificially enhanced diffusivities for both variables. In this study, we use a particle-in-cell method implemented in a 3D dynamo code to conduct a first qualitative exploration of pure compositional convection in a rotating spherical shell. We focus on the end-member case of infinite Schmidt number by totally neglecting the compositional diffusivity. We show that compositional convection has a very rich physics that deserves several more focused and quantitative studies. We also report, for the first time in numerical simulations, the self-consistent formation of a chemically stratified layer at the top of the shell caused by the accumulation of chemical plumes and blobs emitted at the bottom boundary. When applied to likely numbers for the Earth's core, some (possibly simplistic) physical considerations suggest that a stratified layer formed in such a scenario would be probably weakly stratified and may be compatible with magnetic observations.https://www.frontiersin.org/article/10.3389/feart.2019.00099/fullcompositional convectionstratificationcore dynamicsparticle-in-cellinfinite Schmidt number |
| spellingShingle | Mathieu Bouffard Gaël Choblet Stéphane Labrosse Johannes Wicht Chemical Convection and Stratification in the Earth's Outer Core Frontiers in Earth Science compositional convection stratification core dynamics particle-in-cell infinite Schmidt number |
| title | Chemical Convection and Stratification in the Earth's Outer Core |
| title_full | Chemical Convection and Stratification in the Earth's Outer Core |
| title_fullStr | Chemical Convection and Stratification in the Earth's Outer Core |
| title_full_unstemmed | Chemical Convection and Stratification in the Earth's Outer Core |
| title_short | Chemical Convection and Stratification in the Earth's Outer Core |
| title_sort | chemical convection and stratification in the earth s outer core |
| topic | compositional convection stratification core dynamics particle-in-cell infinite Schmidt number |
| url | https://www.frontiersin.org/article/10.3389/feart.2019.00099/full |
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