Global High-Resolution Magnetic Field Inversion Using Spherical Harmonic Representation of Tesseroids as Individual Sources

Abstract

In this study, we present a novel approach combining the advantages of tesseroids in representing geophysical structures though their voxel-like discretization features with a spherical harmonic representation of the magnetic field. Modelling of the Earth lithospheric magnetic field is challenging since part of the spectra is hidden by the core field and the forward modeled field of a lithospheric magnetization is always biased by the spectral range used. In our approach, a spherical harmonic representation of the magnetic field of spherical prisms (tesseroids) is used for high-resolution magnetic inversion of lithospheric field models. The use of filtered spherical harmonic models of the magnetic field of each tesseroid ensures that the resulting field matches the spectral range of the input data. For the inversion, we use the projected gradient method. The projected gradient method easily allows us to assign an initial guess (i.e., a-priori assumption) for the inversion and avoids negative values of susceptibilities. The latter is providing more plausible models since induced magnetization is assumed to be dominant over the continents and, for the oceans, a remanence model can be subtracted. We show an application of the technique to a synthetic dataset and a satellite-derived lithospheric field model where the model geometry is based on seismic information. We also demonstrate a proof-of-concept for high-resolution tile-wise inversion for the Bangui anomaly in Africa.

WITHDRAWN: Can Traditional Chinese Medicine provide insights into controlling the COVID-19 pandemic: Serpentinization-induced lithospheric long-wavelength magnetic anomalies in Proterozoic bedrocks in a weakened geomagnetic field mediate the aberrant transformation of biogenic molecules in COVID-19 via magnetic catalysis

“…The Greater Tethyan Eurasian orogenic belt has active serpentinization of peridotites and significant lithospheric LWMAs ( Fig. 10 ) ( Idoko et al, 2019 ; Guillot et al, 2015 ; Reynard, 2013 ; Baykiev et al, 2020 ). The Appalachian-Ouachita orogenic belt also has active serpentinization of peridotites and significant lithospheric LWMAs ( Fig.…”

Towards a Digital Twin of the Earth System: Geo-Soft-CoRe, a Geoscientific Software & Code Repository

“…A further step in the characterization of the magnetic field encompasses a global high-resolution magnetic field inversion, providing a global heterogeneous coverage based on a spherical harmonic representation. Baykiev et al (2020c) developed the global magnetic inversion code for global high-resolution inversion of satellite magnetic data using spherical harmonic models of tesseroids. Finally, the global magnetic inversion code can be easily linked to LitMod (see Section 3.3.2) to provide a more precise model of the lithosphere, proving its versatility.…”

A Constrained Approach by Curie Point Depth Estimation for the 3‐D Inversion of Regional Lithospheric Magnetic Anomaly Data in Spherical Coordinates and Its Application to the Northern Xinjiang, China

“…Meanwhile, the data altitudes such as 300 km above the mean Earth's radius are very large relative to the thickness of the lithospheric magnetic layer. Therefore, the susceptibility variations in the depth direction of the lithospheric magnetic layer can be ignored, and the whole layer can be considered as a single layer with a radially uniform susceptibility and a constant thickness (e.g., Baykiev et al., 2020; Dyment & Arkani‐Hamed, 1998; Lesur & Vervelidou, 2020; Purucker et al., 1998; von Frese et al., 1981). On the contrary, for the mineral exploration by using the near‐surface magnetic data, a 3‐D model is usually constructed to describe the magnetic sources in the Cartesian coordinate system (CCS; e.g., Lelièvre & Oldenburg, 2009a, 2009b; Li & Oldenburg, 1996, 2003; Li & Sun, 2016; Li et al., 2010; Liu et al., 2013; Pilkington, 1997).…”