MSCM: A geomagnetic model derived from Swarm, CSES, and MSS-1 satellite data and the evolution of the South Atlantic Anomaly

Measurements from geomagnetic satellites continue to underpin advances in geomagnetic field models that describe Earth’s internally generated magnetic field. Here, we present a new field model, MSCM, that integrates vector and scalar data from the Swarm, China Seismo-Electromagnetic Satellite (CSES), and Macau Science Satellite-1 (MSS-1) missions. The model spans from 2014.0 to 2024.5, incorporating the core, lithospheric, and magnetospheric fields, and it shows characteristics similar to other published models based on different data. For the first time, we demonstrate that it is possible to successfully construct a geomagnetic field model that incorporates CSES vector data, albeit one in which the radial and azimuthal CSES vector components are Huber downweighted. We further show that data from the MSS-1 can be integrated within an explicitly smoothed, fully time-dependent model description. Using the MSCM, we identify new behavior of the South Atlantic Anomaly, the broad region of low magnetic field intensity over the southern Atlantic. This prominent feature appears split into a western part and an eastern part, each with its own intensity minimum. Since 2015, the principal western minimum has undergone only modest intensity decreases of 290 nT and westward motion of 20 km per year, whereas the recently formed eastern minimum has shown a 2–3 times greater intensity drop of 730 nT with no apparent east–west motion.