Steady flows at the top of Earth's core derived from geomagnetic field models

1986 ◽  
Vol 91 (B12) ◽  
pp. 12444-12466 ◽  
Author(s):  
Coerte V. Voorhies
Keyword(s):  
Geomagnetic Field ◽  
Steady Flows ◽  
Earth’S Core ◽  
Earth's Core ◽  
Geomagnetic Field Models

Earth's core magnetic field model Mag.num and the IGRF 13 candidate

2020 ◽  
Author(s):  
Martin Rother ◽  
Monika Korte ◽  
Jürgen Matzka ◽  
Achim Morschhauser ◽  
Claudia Stolle ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Field Model ◽  
Secondary Minimum ◽  
Spatial And Temporal Patterns ◽  
Earth’S Core ◽  
Earth's Core ◽  
Geomagnetic Field Models ◽  
Magnetic Field Model ◽  
Swarm Satellite

<p>The Earth's core magnetic field model Mag.num was the parent model for the GFZ IGRF 13 candidate submission. The model is based on geomagnetic ground observatory and Swarm satellite observations. Epochs 2020.0 and beyond were not covered by the data available at the time of submission and our results were based on predictions. In this study, we investigate the effect of the more recent available data on our results of the 2020.0 epoch and the predicted secular variation by generating an updated Mag.num version. We especially focus on the spatial and temporal patterns of the local geomagnetic field minimum of the South Atlantic Anomaly (SAA). Recently, global geomagnetic field models have shown that an additional, although shallow, secondary minimum at Earth's surface has developed since around 2005. The location and significance of the secondary minimum and of the saddle point between the two minima are assessed also in view of the respective differences among the candidate models.</p>

scholarly journals Using symbolic calculations to calculate the eigenmodes of the free damping of a geomagnetic field

2018 ◽  
Vol 62 ◽  
pp. 02018 ◽  
Author(s):  
Gleb Vodinchar
Keyword(s):  
Geomagnetic Field ◽  
Earth’S Core ◽  
Earth's Core ◽  
Symbolic Computations ◽  
Damped Oscillations ◽  
Symbolic Calculations

The method for calculating the eigenmodes of free damped oscillations of the geomagnetic field in the Earth’s core using symbolic computations is described.

scholarly journals Nonlinear MHD Rossby wave interactions and persistent geomagnetic field structures

2020 ◽  
Vol 476 (2241) ◽  
pp. 20200174
Author(s):  
Breno Raphaldini ◽  
Carlos F. M. Raupp
Keyword(s):  
Nonlinear Interaction ◽  
Geomagnetic Field ◽  
Stationary Flow ◽  
Stationary Waves ◽  
Wave Interactions ◽  
Earth’S Core ◽  
Meridional Component ◽  
Earth's Core ◽  
The Core ◽  
Core Dynamics

The geomagnetic field presents several stationary features that are thought to be linked to inhomogeneities at the core–mantle boundary. Particularly important stationary structures of the geomagnetic field are the flux lobes, which appear in pairs in mid- to high mid- to high latitudes. A recently discovered stratified layer at the top of the Earth’s core poses important constraints on the dynamics at this layer and on the interaction of the core dynamics and the base of the mantle. In this article, we introduce the linear and nonlinear theories of magnetic Rossby waves in a thin shell at the top of the Earth’s core. We study the nonlinear interaction of these waves in the presence of prescribed forcings at the base of the mantle of both a thermal and a topographic nature. We show that the combined effects of forcing and nonlinear interaction can lead the wave phases to be locked around a particular geographical longitude, generating a quasi- stationary flow pattern with a significant meridional component. The solutions of the system are shown to be analogous to atmospheric blocking phenomena. Therefore, we argue that persistent and long-lived structures of the geomagnetic field, such as the geomagnetic lobes, might be associated with a blocking at the top of the Earth’s core due to nonlinear stationary waves.

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