Julien Aubert, CNRS, IPG Paris

I am a CNRS senior researcher working at the Institut de Physique du Globe de Paris (IPGP), within the Geological Fluid Dynamics team. 


I am interested in the interpretation of the geomagnetic signal emanating from Earth’s liquid outer core. Over a broad range of space and time scales, this signal is a powerful probe for investigating the structure, dynamics and geological history of our planet. Understanding the geodynamo is an outstanding fundamental challenge of Physical Sciences as well as Earth Sciences. 


To this end I develop and use direct numerical computer simulations of the dynamo process, as well as data assimilation algorithms aiming at forecasting the future evolution of the geomagnetic field. This has important societal impacts as the geomagnetic field interacts with life on Earth and with human technological activities.

what (according to my computer) lies beneath our feet

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Geodynamo simulations spanning millenia at the physical conditions of Earth's core

07/05/2026

In an article published in the new community-driven, diamond open-access Journal of Studies of Earth’s Deep Interiors, I present new simulations of the geodynamo that operate at physical conditions representative of Earth’s core. The novelty here is their millenial duration in physical time, which is enough to study both the long-term convective overturn of the core and the short-term hydromagnetic wave propagation phenomena.


For the first time without the need for extrapolation, a large number of model outputs can be successfully compared to geomagnetic and geodetic observations. This demonstrates the success of the convective geodynamo paradigm at the foundation of these simulations.


Aubert, J: Geodynamo simulations spanning millennia in the physical conditions of Earth's core, Journal of Studies of Earth’s Deep Interior 2, 3, 2026, doi: 10.46298/jsedi.17790

Le champ géomagnétique et la dynamique du noyau de la Terre

18/11/2025

in 2021 I was solicited to write a chapter for an upcoming volume on Earth’s core in the encyclopedia ‘Sciences’ (ISTE editions). As it is now evident that the project of this volume will not come to a successful end, the chapter dedicated to the progress in geodynamo research of the last two decades can be found here (in french):


Aubert, J.: le champ géomagnétique et la dynamique du noyau de la Terre, 2025, hal-05371095

A new reversal mechanism for the geodynamo

06/05/2025

The successful numerical simulation of geomagnetic reversals in the mid 90’s has crucially contributed to the development and popularity of Earth’s core dynamics as a scientific discipline. However, some key difficulties concerning the applicability of numerical results to Earth’s core conditions have remained unsolved since 30 years. In a new paper published in Physics of the Earth and Planetary Interiors, we present a solution to some (but not all) of these problems. The new reversal mechanism that we propose indeed demonstrably applies to the physical conditions of Earth’s core. A puzzling result is that it predicts that a faster cooling of Earth’s core will cause less frequent geomagnetic reversals, whereas previous mechanisms predicted the opposite. This opens interesting prospects for the reanalysis of the reversal records in connection with records of the deep Earth geodynamics.


Note: the copyediting job done by Elsevier on this paper is poor. Some mistakes have been introduced on their side, even after proof stage, such that I cannot recommend their pdf for reference. Please use the one below, from arXiv or from HAL.


Aubert, J., Landeau, M., Fournier, A., Gastine, T.: Core-surface kinematic control of polarity reversals in advanced geodynamo simulations, Phys. Earth. Planet. Int., 2025, doi: 10.1016/j.pepi.2025.107365