The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission carries magnetometers that are dedicated to enhance the satellite’s navigation. After appropriate calibration and characterisation of artificial magnetic disturbances, these observations are valuable assets to characterise the natural variability of Earth’s magnetic field. We describe the data pre-processing, the calibration, and characterisation strategy against a high-precision magnetic field model applied to the GRACE-FO magnetic data. During times of geomagnetic quiet conditions, the mean residual to the magnetic model is around 1 nT with standard deviations below 10 nT. The mean difference to data of ESA’s Swarm mission, which is dedicated to monitor the Earth’s magnetic field, is mainly within ± 10 nT during conjunctions. The performance of GRACE-FO magnetic data is further discussed on selected scientific examples. During a magnetic storm event in August 2018, GRACE-FO reveals the local time dependence of the magnetospheric ring current signature, which is in good agreement with results from a network of ground magnetic observations. Also, derived field-aligned currents (FACs) are applied to monitor auroral FACs that compare well in amplitude and statistical behaviour for local time, hemisphere, and solar wind conditions to approved earlier findings from other missions including Swarm. On a case event, it is demonstrated that the dual-satellite constellation of GRACE-FO is most suitable to derive the persistence of auroral FACs with scale lengths of 180 km or longer. Due to a relatively larger noise level compared to dedicated magnetic missions, GRACE-FO is especially suitable for high-amplitude event studies. However, GRACE-FO is also sensitive to ionospheric signatures even below the noise level within statistical approaches. The combination with data of dedicated magnetic field missions and other missions carrying non-dedicated magnetometers greatly enhances related scientific perspectives.

重力恢复和气候实验跟踪（GRACE-FO）任务携带专门用于增强卫星导航的磁力计。经过对人造电磁干扰进行适当的校准和表征后，这些观测结果对于表征地球磁场的自然变化具有宝贵的价值。我们针对应用于GRACE-FO磁数据的高精度磁场模型描述了数据预处理，校准和表征策略。在地磁安静状态期间，磁模型的平均残差约为1 nT，标准偏差低于10 nT。专门用于监测地球磁场的ESA Swarm任务的数据平均差在合并期间主要在±10 nT以内。GRACE-FO磁数据的性能将在选定的科学实例中进一步讨论。在2018年8月的一次磁暴事件中，GRACE-FO揭示了磁层环电流信号在当地的时间依赖性，这与地面磁观测网络的结果非常吻合。此外，派生的场对准电流（FAC）用于监视极光FAC，这些光在幅度和统计行为方面都可以很好地与当地时间，半球和太阳风状况进行比较，并与其他包括Swarm在内的任务的早期发现相吻合。在一个案例中，事实证明，GRACE-FO的双卫星星座最适合于得出标度长度为180 km或更长的极光FAC的持久性。与专用电磁任务相比，由于噪声水平较高，GRACE-FO特别适用于高振幅事件研究。但是，在统计方法中，即使在噪声水平以下，GRACE-FO也会对电离层特征敏感。结合专用磁场任务和其他携带非专用磁力计的任务的数据，可以大大增强相关的科学视野。