Fitting of magnetic measurements of Swarm satellites based on 3D surface spline model

This study utilizes the 62208000 Swarm satellite data to establish a high-precision main magnetic field at the height of the satellites in China and its adjacent regions. The CHAOS-6 model is used to remove the crustal and external fields and obtain 2788 main field grid data. We use the main field grid data to build a three-dimensional (3D) surface spline (3DSS) model of the satellite altitude in China. Other regional models (namely the 3D, two-dimensional (2D) Taylor, and 2D surface spline models) and the CHAOS-6 model are employed to model and analyze the same region. The results show that the 3DSS model can represent a good fitting for the northward (X) and eastward (Y) components and the total intensity (F). This model demonstrates the most stable results for the 20 points that did not take part in the modeling. Compared with the other three regional models, the root-mean-square error values and the average residuals of the new model are approximately 65% and 69% lower for each component, respectively. This study does not rely on ground station data to derive a more accurate regional main field model. The results further show that less data height difference and high-density data distributions greatly improve the regional model accuracy. The new model has a certain application value to related space geophysics, such as in spatial positioning and navigation, and to the study of regional magnetic anomalies.