Tide-induced magnetic signals and their errors derived from CHAMP and Swarm satellite magnetometer observations

Earth, Planets and Space

Aaron Hornschild¹  Christopher Irrgang¹  Jan Saynisch-Wagner¹  Maik Thomas²  Julien Baerenzung³ 

[1] Earth System Modelling, Helmholtz Centre Potsdam, GFZ German Research Centre, Potsdam, Germany;Earth System Modelling, Helmholtz Centre Potsdam, GFZ German Research Centre, Potsdam, Germany;Department of Earth Sciences, Institute of Meteorology, Freie Universität-Berlin, Berlin, Germany;Potsdam University, Potsdam, Germany;

关键词: Tides;    Electromagnetic induction;    Error covariance;    Satellite magnetometer observations;   

DOI  :  10.1186/s40623-021-01557-3

来源: Springer

【 摘 要 】

Satellite-measured tidal magnetic signals are of growing importance. These fields are mainly used to infer Earth’s mantle conductivity, but also to derive changes in the oceanic heat content. We present a new Kalman filter-based method to derive tidal magnetic fields from satellite magnetometers: KALMAG. The method’s advantage is that it allows to study a precisely estimated posterior error covariance matrix. We present the results of a simultaneous estimation of the magnetic signals of 8 major tides from 17 years of Swarm and CHAMP data. For the first time, robustly derived posterior error distributions are reported along with the reported tidal magnetic fields. The results are compared to other estimates that are either based on numerical forward models or on satellite inversions of the same data. For all comparisons, maximal differences and the corresponding globally averaged RMSE are reported. We found that the inter-product differences are comparable with the KALMAG-based errors only in a global mean sense. Here, all approaches give values of the same order, e.g., 0.09 nT-0.14 nT for M2. Locally, the KALMAG posterior errors are up to one order smaller than the inter-product differences, e.g., 0.12 nT vs. 0.96 nT for M2.Graphical Abstract

【 授权许可】

CC BY