A5039542404- Geophysical and Geoelectrical Methods
- Geomagnetism and Paleomagnetism Studies
- Geological and Geophysical Studies
- Earthquake Detection and Analysis
- Geophysics and Gravity Measurements
- Seismic Waves and Analysis
- Geophysical Methods and Applications
- Geological and Geochemical Analysis
- Seismic Imaging and Inversion Techniques
- Geochemistry and Geologic Mapping
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Scientific Research and Discoveries
- Ionosphere and magnetosphere dynamics
- Planetary Science and Exploration
- High-pressure geophysics and materials
- Electromagnetic Simulation and Numerical Methods
- earthquake and tectonic studies
- Underwater Acoustics Research
- Electrical and Bioimpedance Tomography
- Geothermal Energy Systems and Applications
- Electromagnetic Scattering and Analysis
- Stellar, planetary, and galactic studies
- Advanced Numerical Methods in Computational Mathematics
- Oceanographic and Atmospheric Processes
University of Cologne
2022-2025
Czech Academy of Sciences, Institute of Geophysics
2025
ETH Zurich
2014-2023
École Polytechnique Fédérale de Lausanne
2016-2021
Board of the Swiss Federal Institutes of Technology
2018-2020
Elektrometall (Czechia)
2020
GFZ Helmholtz Centre for Geosciences
2012-2014
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...
We present the CHAOS-7 model of time-dependent near-Earth geomagnetic field between 1999 and 2020 based on magnetic observations collected by low-Earth orbit satellites Swarm, CryoSat-2, CHAMP, SAC-C Ørsted, annual differences monthly means ground observatory measurements. The consists a internal up to spherical harmonic degree 20, static which merges LCS-1 lithospheric above 25, magnetospheric its induced counterpart, estimates Euler angles describing alignment satellite vector...
Abstract This paper provides an overview of the new features finite element library deal.II, version 9.2.
For 3-D inversion of controlled-source electromagnetic (CSEM) data, increasing availability high-performance computers enables us to apply techniques that are theoretically favourable, yet have previously been considered be computationally too demanding. We present a newly developed parallel distributed algorithm for interpreting CSEM data in the frequency domain. Our scheme is based on direct forward solver and uses Gauss–Newton minimization with explicit formation Jacobian. This...
We have investigated the use of adaptive high-order finite-element method (FEM) for geoelectromagnetic modeling. Because FEM is challenging from numerical and computational points view, most published studies in geoelectromagnetics lowest order formulation. Solution resulting large system linear equations poses main practical challenge. developed a fully parallel distributed robust scalable solver based on optimal block-diagonal auxiliary space preconditioners. The was found to be efficient...
We present a new global electrical conductivity model of Earth's mantle. The was derived by using novel methodology, which is based on inverting satellite magnetic field measurements from different sources simultaneously. Specifically, we estimated responses magnetospheric origin and ocean tidal signals the most recent Swarm CHAMP data. challenging task properly accounting for effect in data addressed through full three-dimensional solution Maxwell's equations. show that simultaneous...
We present a robust and scalable solver for time-harmonic Maxwell's equations problems with large conductivity contrasts, wide range of frequencies, stretched grids locally refined meshes. The is part the fully distributed adaptive 3-D electromagnetic modelling scheme which employs finite element method unstructured non-conforming hexahedral meshes spatial discretization using open-source software deal.II. use complex-valued electric field formulation split it into two real-valued we utilize...
We evaluated 3D inversion of land controlled-source electromagnetic (CSEM) data collected across the Ketzin [Formula: see text] storage formation. A newly developed, parallel and distributed code, which is based on a direct forward solver, has been used. This scheme allowed us to calculate Jacobian matrix explicitly within reasonable time use it regularization parameters, inspect survey coverage, carry out resolution analysis. After demonstrating that magnetic field components are sensitive...
Abstract Continental rifting is initiated by a dynamic interplay between tectonic stretching and mantle upwelling. Decompression melting assists continental breakup through lithospheric weakening enforces upflow of melt to the Earth's surface. However, details about transport brittle crust storage under narrow rift‐aligned magmatic segments remain largely unclear. Here we present crustal‐scale electrical conductivity model for segment in Ethiopian Rift, derived from 3‐D phase tensor...
This paper presents a distributed magnetotelluric inversion scheme based on adaptive finite-element method (FEM). The key novel aspect of the introduced algorithm is use automatic mesh refinement techniques for both forward and inverse modelling. These alleviate tedious subjective procedure choosing suitable model parametrization. To avoid overparametrization, meshes problems were decoupled. For calculation accurate electromagnetic (EM) responses, goal-oriented error estimator has been...
SUMMARY Central Mongolia is a prominent region of intracontinental surface deformation and intraplate volcanism. To study these processes, which are poorly understood, we collected magnetotelluric (MT) data in the Hangai Gobi-Altai central derived first 3-D resistivity model crustal upper mantle structure this region. The geological tectonic history complex, resulting features over wide range spatial scales, that coupled through variety geodynamic processes. Many Earth properties critical...
Abstract This study presents results of mapping three-dimensional (3-D) variations the electrical conductivity in depths ranging from 400 to 1200 km using 6 years magnetic data Swarm and CryoSat-2 satellites as well ground observatories. The approach involves 3-D inversion matrix Q-responses (transfer functions) that relate spherical harmonic coefficients external (inducing) internal (induced) origin potential. Transfer functions were estimated geomagnetic field at periods 2 40 days. We...
The tidal flow of electrically conductive oceans through the geomagnetic field results in generation secondary magnetic signals, which provide information on subsurface structure. Data from new satellites were shown to contain signals due flow; however, there are no reports that these have been used infer We use satellite-detected fields image global electrical structure oceanic lithosphere and upper mantle down a depth about 250 km. model derived more than 12 years satellite data reveals...
Abstract Southern Mongolia is part of the Central Asian Orogenic Belt, origin and evolution which not fully known often debated. It composed several east–west trending lithostratigraphic domains that are attributed to an assemblage accreted terranes or tectonic zones. This in contrast Mongolia, dominated by a cratonic block Hangai region. Terranes typically bounded suture zones expected be deep-reaching, but may difficult identify based on observable surface fault traces alone. Thus,...
Abstract This review presents the progress made in last decade field of large-scale electromagnetic (EM) induction with natural sources, which fluctuate at periods from seconds to years and originate oceans, ionosphere magnetosphere. These mechanisms produce variations that can be used image subsurface electrical structure Earth planets across scales depths shallow crust lower mantle. In decade, we have seen a substantial different areas related methods, observations 3-D numerical modelling...
Abstract In this paper we estimate and invert local electromagnetic (EM) sounding data for 1‐D conductivity profiles in the presence of nonuniform oceans continents to most rigorously account ocean induction effect that is known strongly influence coastal observatories. We consider a new set high‐quality time series geomagnetic observatory data, including hitherto unused from island observatories installed over last decade. The EM are inverted period range 3–85 days using stochastic...
Abstract This paper presents a methodology to sample equivalence domain (ED) in nonlinear partial differential equation (PDE)-constrained inverse problems. For this purpose, we first applied state-of-the-art stochastic optimization algorithm called Covariance Matrix Adaptation Evolution Strategy (CMAES) identify low-misfit regions of the model space. These were then randomly sampled create an ensemble equivalent models and quantify uncertainty. CMAES is aimed at exploring space globally...
Abstract We present electrical resistivity models, derived from magnetotelluric data, of the crust beneath Bulnay region, Mongolia. They reveal that lower contains a pattern discrete zones (width ~25 km) low (<30 Ωm). Such features may be an effect unaccounted‐for anisotropy. However, when anisotropy is considered in modeling, remain. investigate alternative explanation, based on conceptual model fluid localization and stagnation by thermally activated compaction, demonstrate it...
Geophysical and petrological probes are key to understanding the structure thermochemical state of active magmatic systems. Recent advances in laboratory analyses, field investigations numerical methods have allowed increasingly complex data-constraint models with new insights into magma plumbing systems melt evolution. However, there is still a need for quantitatively link geophysical observables more consistent description processes at both micro- macro-scales. Whilst modern studies...
Abstract This study presents global 3‐D electrical conductivity models of the world ocean and marine sediments. Electrical was calculated by invoking Equation State Seawater (TEOS‐10) with temperature salinity data retrieved from World Ocean Atlas a series high‐resolution regional climatology sets. The resolution atlas varies between 0. globally. sediments estimated using compaction thermal gradient constrained real observations on 5‐arc‐minute sediment thickness grid. I present numerical...
Summary The time-varying geomagnetic field is a superposition of contributions from multiple internal and external current systems. A major source variations at periods less than few years are systems to the solid Earth, namely ionospheric magnetospheric currents, as well associated induced currents. separation these three sources mathematically underdetermined using either ground or satellite measurements alone, but becomes tractable when two datasets combined. Based on this concept, we...
The NASA InSight mission operated on Mars from November 2018 to May 2022, primarily&#160; aimed at investigating the planet&#8217;s interior structure using seismology, geodesy, and heat flow measurements. Among its instruments was Fluxgate magnetometer, IFG, part of an auxiliary sensor suite, which provided environmental monitoring data. IFG captured first surface measurements Mars&#8217; crustal magnetic field, as well time-varying fields. These data enable electromagnetic (EM)...
Over the last two decades, controlled source (CS) electromagnetic (EM) methods using an extended frequency range from 1-1000 kHz have been developed. Controlled sources complement Radio-magnetotellurics (RMT) method by providing a wider range, greater depth of investigation and more stable responses. In addition, they remain operational even without radio antennas in vicinity measurement area. While initially CS-/RMT was originally considered only far-field conditions, it has recently to...
Summary We present new transfer functions (TFs) that can handle external electromagnetic (EM) sources of complex geometry. These TFs relate global expansion coefficients describing the source with a locally measured EM field. In this study, concept was applied to daily magnetic variations at ground. The parameterisation in terms spherical harmonics adopted. used nearly 20 years data from 125 mid-latitude observatories and explored how results are affected by (I) solar activity conditions,...