NGDC-720V4QT: A revised model of the global lithospheric magnetic field to fill the data gap in the Qinghai-Tibet Plateau

Existing magnetic anomaly datasets, such as EMAG2, contain significant data gaps that severely undermine the accuracy of high-resolution lithospheric field modeling in certain regions. For example, the NGDC-720 model has limited spatial resolution for wavelengths shorter than 330 km over the Qinghai-Tibet Plateau, as it relies solely on satellite-derived data due to incomplete coverage in EMAG2. Updating this model with newly available near-surface magnetic measurements is crucial to address these deficiencies. However, developing a revised model requires substantial computational resources and time, which likely explains the lack of revisions to the NGDC-720 model since the release of its third version over two decades ago. To overcome this challenge, we propose an innovative methodology for efficiently updating the spherical harmonic representation of the lithospheric magnetic field. By adopting this approach, we incorporate high-precision aeromagnetic data from the Qinghai-Tibet Plateau into the NGDC-720 model, enhancing its spatial resolution from a 330 km wavelength to a 56 km wavelength in this region. The updated model not only provides high-resolution regional magnetic anomaly data but also maintains consistency with the original NGDC-720 model, revealing key tectonic structures. Our findings suggest that this approach holds significant potential for updating global lithospheric magnetic field models through localized refinements.