共同估计geomagnetic field和校准参数：用平台磁强计数据模拟地球磁场
Co-estimating geomagnetic field and calibration parameters: modeling Earth's magnetic field with platform magnetometer data
摘要：
地磁场模型依赖于高空间和时间分辨率的磁测数据。CHAMP和Swarm等专门磁测任务的低地球轨道卫星的磁测数据在构建此类模型方面发挥着关键作用。不幸的是，在2010年CHAMP结束之后和2013年底Swarm发射之前，没有来自此类卫星的磁性数据。这限制了我们在3年或更短时间内恢复信号的能力。卫星为导航目的携带的平台磁力计提供的磁力数据，如果经过仔细校准，可能有助于弥补这一数据空白。早期的研究表明，平台磁强计数据可以使用固定的参考场模型进行校准。然而，这种方法可能导致有偏差的校准参数。一种替代方案已被开发的共同估计计划，其中包括同时估计的校准参数和内部地磁场的模型的形式。在这里，我们开发了一个计划，混沌框架的基础上，涉及共同估计的地磁场模型以及校准参数的平台磁强计。使用我们的实现，我们能够推导出从2008年到2018年的地磁场模型，卫星磁数据来自CHAMP，Swarm，长期变化数据来自地面观测站，平台磁强计数据来自CryoSat-2和GRACE。通过实验，我们探索的地磁场和校准参数的估计之间的相关性，并建议如何避免这些。我们发现，平台磁强计数据提供了额外的信息，特别是在太平洋的长期加速度的间隙期间。该研究进一步证明了在地磁场建模中使用平台磁强计数据是有益的。
英文摘要：
Models of the geomagnetic field rely on magnetic data of high spatial and temporal resolution. The magnetic data from low-Earth orbit satellites of dedicated magnetic survey missions such as CHAMP and Swarm play a key role in the construction of such models. Unfortunately, there are no magnetic data from such satellites after the end of CHAMP in 2010 and before the launch of Swarm in late 2013. This limits our ability to recover signals on timescales of 3 years and less during this gap period. The magnetic data from platform magnetometers carried by satellites for navigational purposes may help address this data gap provided that they are carefully calibrated. Earlier studies have demonstrated that platform magnetometer data can be calibrated using a fixed reference field model. However, this approach can lead to biased calibration parameters. An alternative has been developed in the form of a co-estimation scheme which consists of simultaneously estimating both the calibration parameters and a model of the internal geomagnetic field. Here, we develop a scheme, based on the CHAOS framework, that involves the co-estimation of a geomagnetic field model along with calibration parameters of platform magnetometers. Using our implementation, we are able to derive a geomagnetic field model from 2008 to 2018 with satellite magnetic data from CHAMP, Swarm, secular variation data from ground observatories, and platform magnetometer data from CryoSat-2 and GRACE. Through experiments, we explore correlations between the estimates of the geomagnetic field and the calibration parameters, and suggest how these may be avoided. We find that platform magnetometer data provide additional information on the secular acceleration, especially in the Pacific during the gap period. This study adds to the evidence that it is beneficial to use platform magnetometer data in geomagnetic field modeling.
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