A high-resolution lithospheric magnetic field model over southern Africa based on a joint inversion of CHAMP, Swarm, WDMAM, and ground magnetic field data

Abstract

Abstract. We derive a lithospheric magnetic field model up to equivalent spherical harmonic degree 1000 over southern Africa. We rely on a joint inversion of satellite, near-surface, and ground magnetic field data. The input data set consists of magnetic field vector measurements from the CHAMP satellite, across-track magnetic field differences from the Swarm mission, the World Digital Magnetic Anomaly Map, and magnetic field measurements from repeat stations and three local INTERMAGNET observatories. For the inversion scheme, we use the revised spherical cap harmonic analysis (R-SCHA), a regional analysis technique able to deal with magnetic field measurements obtained at different altitudes. The model is carefully assessed and displayed at different altitudes and its spectral content is compared to high-resolution global lithospheric field models. By comparing the shape of its spectrum to a statistical power spectrum of Earth's lithospheric magnetic field, we infer the mean magnetic thickness and the mean magnetization over southern Africa.