Progress and challenges in modeling global lithospheric magnetic anomalies

Over the past 50 years, extensive airborne and oceanic magnetic survey data collection efforts have resulted in the almost complete coverage of near-surface magnetic survey data worldwide. National and intercontinental magnetic anomaly maps have also been generated. Advancements in satellite magnetic field measurements, such as those from CHAllenging Minisatellite Payload (CHAMP), provided longwave magnetic anomaly backgrounds on a global scale. This has led to the realization of global magnetic anomaly grids with arcminute resolutions, such as the World Digital Magnetic Anomaly Map (WDMAM). Utilizing these datasets, spherical harmonic coefficient models such as the NGDC-720 model have been established for lithospheric magnetic fields. The global lithospheric magnetic anomaly model has progressed considerably; for example, the shortest wavelengths reflected in the spatial resolution have improved from hundreds of kilometers to tens of kilometers. However, modeling still faces major challenges; for example, the accuracy of the model remains low, amounting to a few hundred nanotesla. In this study, we provide a comprehensive review of the techniques for compiling magnetic anomalies at various scales and discuss the key methodologies for processing and compiling them. Furthermore, we address the complexities involved in modeling the global lithospheric magnetic field. Our objective was to address the shortcomings of lithospheric magnetic anomaly modeling and develop a high-precision, independent, and controllable lithospheric magnetic field model for China.