Investigation of the consistency of Swarm data and CHAOS-6 towards crustal magnetic field studies in China

We investigate using satellite geomagnetic data and their derived field models to study the crustal field. We focus on China to understand whether field models completely explain the crustal field of the regional extent and whether a high-quality satellite contains additional information, particularly on small scales, enhancing crustal field studies and improving model resolution. We use Swarm satellite data and the CHAOS-6 model and examine along-track one-degree differences in latitude bin averages of satellite data to seek additional small-scale structures. The results show that the CHAOS-6 model does a very good job of explaining the data. The mean square deviation is ∼3 nT. Moreover, the model broadly explains secular variation with certain misfits but not consistent between tracks. We report an anomalous unmodeled feature in the data. However, as this is located close to the magnetic equator, this may be attributed to an external field source. We conclude that crustal field studies should primarily focus on models and not data.