Modelling of Geomagnetic Secular Variation with Swarm: past, present and future

摘要

The magnetic field generated by the motion in Earth’s fluid outer core is by far the largest contribution to the geomagnetic field. The shape and intensity of this field changes through time (known as secular variation), occasionally in unpredictable ways. We observe this field evolution with missions such as the Swarm constellation of Earth observation satellites. From such measurements, models of the geomagnetic field can be built to study the temporal and spatial variations, from the core’s surface to satellite altitudes.udWe present results derived from the latest iteration of the BGS Model of the Earth’s Magnetic Environment (MEME), updated with the latest Swarm and ground observatory data from 2017 as well as data from previous satellite missions CHAMP and Ørsted. Given that recent secular variation has been significant in some regions, with rapid variations known as geomagnetic jerks observed in 2014 and 2015, we assess how well these changes are captured by this model, particularly when in close proximity to the end of the data span. We also look ahead to the state of the geomagnetic field in the near future as predicted by extrapolation of MEME and provide an outlook on possible future orbit evolutions of the Swarm satellites.ud