A5079297873- Geomagnetism and Paleomagnetism Studies
- Geophysics and Gravity Measurements
- Geology and Paleoclimatology Research
- Solar and Space Plasma Dynamics
- Geophysical and Geoelectrical Methods
- High-pressure geophysics and materials
- Seismic Imaging and Inversion Techniques
- Astro and Planetary Science
- Geological and Geochemical Analysis
- Seismic Waves and Analysis
- earthquake and tectonic studies
- Ionosphere and magnetosphere dynamics
- Geological formations and processes
- Earthquake Detection and Analysis
- Reservoir Engineering and Simulation Methods
- Geochemistry and Geologic Mapping
- Archaeology and ancient environmental studies
- Meteorological Phenomena and Simulations
- Stellar, planetary, and galactic studies
- Fluid Dynamics and Turbulent Flows
- Characterization and Applications of Magnetic Nanoparticles
- Graph Theory and Algorithms
- Remote-Sensing Image Classification
- Advanced Vision and Imaging
- Remote Sensing in Agriculture
Institut Laue-Langevin
2025
Institut de physique du globe de Paris
2015-2024
Université Paris Cité
2014-2024
The University of Melbourne
2023
Centre National de la Recherche Scientifique
2013-2022
John Brown University
2022
Sorbonne Paris Cité
2011-2020
Université de Bourgogne
2019
New York University Press
2017
Cambridge University Press
2017
The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by Working Group V-MOD appointed Association Geomagnetism and Aeronomy (IAGA). It updates previous IGRF with a definitive main field model for epoch 2010.0, 2015.0, linear annual predictive secular variation 2015.0-2020.0. Here, we present equations defining model, provide spherical harmonic coefficients, maps magnetic declination, inclination, total intensity 2015.0 their predicted rates...
Abstract In December 2019, the International Association of Geomagnetism and Aeronomy (IAGA) Division V Working Group (V-MOD) adopted thirteenth generation Geomagnetic Reference Field (IGRF). This IGRF updates previous with a definitive main field model for epoch 2015.0, 2020.0, predictive linear secular variation 2020.0 to 2025.0. letter provides equations defining IGRF, spherical harmonic coefficients this model, maps magnetic declination, inclination total intensity their predicted rate...
Abstract. We present a methodology to compute 3-D global seismic wavefields for realistic earthquake sources in visco-elastic anisotropic media, covering applications across the observable frequency band with moderate computational resources. This is accommodated by mandating axisymmetric background models that allow multipole expansion such only 2-D domain needed, whereas azimuthal third dimension computed analytically on fly. dimensional collapse opens doors storing space–time disk can be...
We present an attempt to reach realistic turbulent regime in direct numerical simulations of the geodynamo. rely on a sequence three convection-driven rapidly rotating spherical shell. The most extreme case reaches towards Earth's core by lowering viscosity (magnetic Prandtl number Pm=0.1) while maintaining vigorous convection Reynolds Rm>500) and rapid rotation (Ekman E=1e-7), at limit what is feasible today's supercomputers. A detailed comprehensive analysis highlights several key features...
Self-sustained convective dynamos in planetary systems operate an asymptotic regime of rapid rotation, where a balance is thought to hold between the Coriolis, pressure, buoyancy and Lorentz forces (the MAC balance). Classical numerical solutions have previously been obtained moderate rotation viscous inertial are still significant. We define uni-dimensional path parameter space classical models conditions from requirements enforce preserve ratio magnetic diffusion overturn times Reynolds...
SUMMARY Heterosis, also known as hybrid vigor, is the phenomenon wherein a progeny exhibits superior traits relative to one or both parents. In terms of crop breeding, this usually refers yield advantage F 1 hybrids over inbred The development high‐yielding cultivars across wider range crops key meeting future food demands. However, conventional breeding strategies are proving be exceptionally challenging apply commercially in many self‐pollinating crops, particularly wheat and barley....
The knowledge of the spatial power spectra main geomagnetic field and its secular variation makes it possible to define typical timescales τ n for each spherical harmonic degree . Investigating both observations numerical dynamos, we show that a one‐parameter law form = SV / is satisfied non‐dipole field, given statistical way observed are expected fluctuate. Consequently, determine corresponding secular‐variation timescale from either instantaneous or time‐averaged spectra, leading value...
With the progress of mantle convection modelling over last decade, it now becomes possible to solve for dynamics interior flow and surface tectonics first order. We show here that tectonic data (like kinematics seafloor age distribution) models with plate-like behaviour can in principle be combined reconstruct convection. present a sequential assimilation method, based on suboptimal schemes derived from Kalman filter, where velocities maps are not used as boundary conditions flow, but...
The existence of a stably stratified layer underneath the core-mantle boundary (CMB) has been recently revived by corroborating evidences coming from seismic studies, mineral physics and thermal evolution models. Such could find its physical origination either in compositional stratification due to accumulation light elements at top or core heat flux becoming locally sub-adiabatic. exact properties this stably-stratified layer, namely size $\mathcal{H}_S$ degree characterised...
We develop a spectral‐element method for computing the full 3‐D moment‐tensor and point‐force response of spherically symmetric earth model in 2‐D semi‐circular computational domain. The elastodynamic to six‐component moment tensor at an earthquake hypocentre three‐component point force seismic station can be determined by solving six independent problems, three monopole source, two dipole one quadrupole source. This divide‐and‐conquer reduction strategy provides basis efficient computation...
Recent studies (Ben-Yosef et al., 2009, Shaar 2011) propose extreme archeomagnetic intensity changes (termed spikes) in the range ∼4–5μT/year c.a. 1000 BC Near East, around 40 to 50 times larger than values typical of present-day. In order investigate whether such are consistent with a model source region magnetic field, namely fluid flow at surface Earth's core, we construct upper bounds for instantaneous change an arbitrary site on surface. These constrained by amount kinetic energy...
The construction of geomagnetic, archaeomagnetic or palaeomagnetic field models requires some prior knowledge about the actual field, which can be gathered from statistical properties over a variety length-scales and timescales. However, available geomagnetic data on centennial to millennial periods are too sparse infer directly these properties. We thus use high-resolution numerical simulations geodynamo test method for estimating temporal power spectra (or equivalently autocovariance...
The EU Center of Excellence for Exascale in Solid Earth (ChEESE) develops exascale transition capabilities the domain Earth, an area geophysics rich computational challenges embracing different approaches to (capability, capacity, and urgent computing). first implementation phase project (ChEESE-1P; 2018–2022) addressed scientific technical seismology, tsunami science, volcanology, magnetohydrodynamics, order understand phenomena, anticipate impact natural disasters, contribute risk...
In order to characterize the global circulation of subsurface ocean Jovian and Saturnian moons, we analyze properties 21 three-dimensional simulations Boussinesq thermal convection in a rapidly rotating spherical shell. Flow is driven by an adverse temperature contrast imposed across domain, subjected no-slip boundary conditions. We cover region parameter space previously unexplored simulations, both terms rapid rotation vigor convective forcing, closer to, yet still admittedly far from,...
We portray a dedicated spectral-element method to solve the elastodynamic wave equation upon spherically symmetric earth models at expense of 2-D domain. Using this method, 3-D wavefields arbitrary resolution may be computed obtain Fréchet sensitivity kernels, especially for diffracted arrivals. The meshing process is presented varying frequencies in terms its efficiency as measured by total number elements, their spacing variations and stability criteria. assess mesh quantitatively defining...
We present the application of ensemble Kalman filter to a three‐dimensional, convection‐driven model geodynamo. Our implementation rests on suitably modified version parallel data assimilation framework Nerger and Hiller (2013). resort closed‐loop experiments for validation purposes, using dynamo intermediate resolution. Observations these consist spectral coefficients describing surface poloidal magnetic field, with arbitrary truncation. synthetic tests demonstrate efficacy adaptivity...
SUMMARY Geomagnetic jerks—abrupt changes in the acceleration of Earth’s magnetic field that punctuate geomagnetic records— have been richly documented over past decades by taking advantage complementary strengths ground observatory and satellite measurements. It has recently proposed these events originate from interplay timescale separation between slow convection rapid hydromagnetic wave propagation outer core, with latter waves playing a key role generation jerk signals. To assess...
Abstract. Secular variations of the geomagnetic field have been measured with a continuously improving accuracy during last few hundred years, culminating nowadays satellite data. It is however well known that dynamics magnetic linked to velocity in core and any attempt model secular will involve coupled dynamical system for velocity. Unfortunately, there no direct observation Independently exact nature above-mentioned – some version being currently under construction question debated this...