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| Titel |
Lateral core mantle boundary heat flux variations as a model of Martian paleomagnetic field |
| VerfasserIn |
Wieland Dietrich, Johannes Wicht |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250045153
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| Zusammenfassung |
| The presence of a strong crustal magnetization on Mars indicates an ancient magnetic field. The dichotomy in the crustal magnetization between the northern and southern hemisphere supports the idea of a hemispherical magnetic field at the late stage of the dynamo action. The flow in the underlying core is strongly influenced by the mantle convection. A significant feature of the Martian mantle dynamics is low degree mantle convection leading to a lateral inhomogeneous heat flux at the Core Mantle Boundary (CMB) and affect the dynamics of the liquid iron core. We explore the dynamo action in this scenario imposed by low degree mantle convection and investigate the effect on the morphology of the magnetic field. We model the Martian dynamo, which is imposed by a degree-one lateral variation of the heat flux at the CMB, as a spherical shell of conducting fluid in a full MHD numerical simulation. The flow is driven only by volumetric internal heating, since we assume no solid inner core. The lateral heat flux variations at the CMB are considered as a degree-1 heat flux perturbations with small amplitude. We systematically investigate the dependence of the amplitude of the perturbation and its tilt angle with respect to the rotation axis on the dynamo field configuration. In the hemisphere of higher heat flux the vigor of the dynamo action is amplified when on the other hemisphere the temperature gradient driven thermal convection is weakened. As a consequence, the north-south symmetry of the dynamo ceases and a hemispherical configuration is preferred. |
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