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, CSES, and MSS-1 satellites. The model spans 2014.0 to 2024.5, incorporating the core, lithospheric, and magnetospheric fields, showing similar characteristics to other published models. For the first time, we demonstrate that incorporating CSES vector data successfully produces a geomagnetic field model, albeit one in which the radial and azimuthal CSES vector components are Huber downweighted. We further show that data from MSS-1 can be used to construct a fully time-dependent geomagnetic field model. MSCM identifies new behaviour 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 and 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 20km/yr, while the recently-formed eastern minimum has shown an intensity drop 2-3 times greater of 730nT with no apparent motion.