Space magnetometry: mapping Earth’s magnetic field with satellites

Abstract Magnetic measurements from low earth orbiting (LEO) satellites have revolutionised our ability to globally map Earth’s magnetic field. This paper reviews the processing and calibration of satellite magnetometer data from both dedicated magnetic field missions and satellites carrying platform magnetometers. It describes the successive steps of vector magnetometer calibration, characterisation of spacecraft disturbance fields and alignment of the corrected magnetic field vectors into an Earth-fixed reference frame. Different parametrisations for these steps are discussed, including approaches to account for time- and temperature-dependent effects and non-linear response of the magnetometer. Dedicated missions such as Ørsted, CHAMP, Swarm and MSS-1, equipped with absolute scalar magnetometers, allow separate and highly accurate calibration steps; whereas, platform magnetometers on missions such as CryoSat-2, GRACE and GRACE-FO require joint estimation procedures using geomagnetic field models as reference. Despite their limitations, platform magnetometer data are a valuable supplement to dedicated missions, offering improved space–time coverage for modelling ionospheric, magnetospheric and induced magnetic field contributions. Recent advances in automated calibration are highlighted, underscoring the growing role of non-dedicated satellites in geomagnetic research. Graphical Abstract