Reflection and Refraction of Plane Waves at the Interface of Two Visco-thermoelastic Liquid Layers in Presence of Magnetic Field and Compressional Stress, with the Outer Core Inside the Earth as a Model

<div> To understand the processes involved in the deep interior of the Earth and explaining its evolution, in particular the dynamics of the Earth&#8217;s fluid iron-rich outer core, only indirect satellite and ground observations are available. They each provide invaluable information about the core flow but are incomplete on their own: -&#160;&#160;&#160;&#160;&#160;&#160;&#160; The time dependent magnetic field, originating mainly within the core, can be used to infer the motions of the fluid at the top of the core on decadal and subdecadal time scales. -&#160;&#160;&#160;&#160;&#160;&#160;&#160; The time dependent gravity field variations that reflect changes in the mass distribution within the Earth and at its surface occur on a broad range of time scales. Decadal and interannual variations include the signature of the flow inside the core, though they are largely dominated by surface contributions related to the global water cycle and climate-driven land ice loss. -&#160;&#160;&#160;&#160;&#160;&#160;&#160; Earth rotation changes (or variations in the length of the day) also occur on these time scales, and are largely related to the core fluid motions through exchange of angular momentum between the core and the mantle at the core-mantle boundary. Here, we present the main activities proposed in the frame of the GRACEFUL ERC project, which aims to combine information about the core deduced from the gravity field, from the magnetic field and from the Earth rotation in synergy, in order to examine in unprecedented depth the dynamical processes occurring inside the core and at the core-mantle boundary. </div>

Download Full-text

Simplified model for axial dipole moment of the geomagnetic field from Brownian fluctuations

10.5194/egusphere-egu2020-19012 ◽

2020 ◽

Author(s):

Alberto Molina Cardín ◽

Luis Dinis Vizcaíno ◽

María Luisa Osete López

Keyword(s):

Magnetic Field ◽

Dipole Moment ◽

Stochastic Dynamics ◽

Computational Cost ◽

Temporal Distribution ◽

Outer Core ◽

Axial Dipole ◽

The Earth ◽

Earth Magnetic Field ◽

The Magnetic Field

The magnetic field of the Earth is generated in its core by the process called the geodynamo, which involves convection in the fluid and electrical conducting outer core. The evolution of this complex process is simulated by magnetohydrodynamic models, which provide the state of the core and the magnetic field at any point and any time of the simulation. Nevertheless, the complexity of these models implies a high computational cost. That is why conceptual simple models describing only the main mechanisms from a statistical perspective can also be useful.In this work we present a conceptual model that reproduces the main features of the axial dipole moment (ADM) of the Earth magnetic field. It is based on the stochastic dynamics of two Brownian particles interacting with each other within a double-well potential. The obtained simulations are able to mimic the random temporal distribution of reversals and excursions and the asymmetric temporal evolution of ADM during reversals. The relation between the model features and the real mechanisms that lead to the observed behaviour is discussed.

Download Full-text