Optimizing calibration of fluxgate magnetometer offsets using magnetic holes in the earth’s magnetosheath

Abstract The offset of the fluxgate magnetometer (FGM) drifts slowly with time and temperature, requiring regular in-flight calibration. Recent studies utilizing magnetic holes have optimized calibration error to ~ 0.3 nT in the solar wind, but an order larger in the Earth’s magnetosheath. Previous magnetic hole calibration is based on the 1D assumption that the magnetic field of the magnetic hole varies only along its axial direction. In this study, we show that the calibration accuracy is primarily affected by the 3D configuration of magnetic holes, background magnetic field, and satellite trajectory related to magnetic holes. To address these challenges, we consider a 3D magnetic bottle-like topology of the magnetic hole and introduce an equal-weight random sampling method and a symmetry recognition algorithm to optimize the FGM calibration error to ~ 0.5 nT in the magnetosheath based on Cluster and magnetospheric multiscale (MMS) mission data, achieving an order-of-magnitude improvement in accuracy. This study offers a novel solution for improving FGM calibration in planetary magnetosheaths, such as the upcoming solar wind–magnetosphere–ionosphere link explorer (SMILE) mission, ensuring more accurate magnetic field observations. Graphical Abstract