A method for simultaneously determining Earth's magnetic field and mantle conductivity models using MSS-1 and Swarm satellite magnetic data

Abstract

The magnetospheric primary and its Earth mantle-induced fields are essential components of geomagnetic field models. Previous geomagnetic field modeling methods typically use a fixed a priori Earth's mantle conductivity model to account for the induced field. This treatment may reduce accuracy, as electromagnetic induction depends on conductivity models. Here, we propose a new method that simultaneously determines the mantle conductivity model during geomagnetic field modeling. This method has the advantages of (i) self-consistently accounting for the induced field in geomagnetic field modeling, and (ii) simultaneously providing valuable information on Earth's internal structure. We implement the method into a new computationally parallel field modeling framework, which scales nearly linearly up to a large number of MPI cores. The Macau Science Satellite-1 (MSS-1), primarily aiming to accurately measure the Earth's magnetic field, was successfully launched on May 21, 2023. We apply our method to the magnetic data from MSS-1 as well as Swarm satellites and obtain the first self-consistent models of Earth's magnetic field and mantle conductivity. We also investigate how different conductivity models affect geomagnetic field modeling. Our results show that a fixed a priori conductivity model introduces field differences of about 2–4 nT in magnetic field models. These field differences, which are larger than the measuring accuracy of modern geomagnetic satellites, can be avoided by our method.