Extracting lithospheric signals from MSS-1 magnetic data by using singular spectrum analysis and correlation analysis

The satellite magnetic survey serves as a critical approach for investigating the global lithospheric magnetic field, yet the original data are contaminated by multiple interfering signals (e.g., the main magnetic field, external magnetic field, induced magnetic field, and instrumental noise). Thus, reliably extracting the lithospheric magnetic signal from satellite magnetic measurements is an important and basic work for further modeling the lithospheric magnetic field. To address this challenge, we introduced the singular spectrum analysis (SSA) to the residual data after traditional corrections and selection of the satellite magnetic measurements. To determine the optimal reconstruction parameters of the SSA, a correlation analysis among nearest-neighbor orbits was performed. Here, as a case study, we applied the proposed method to magnetic measurements (November 2023 to April 2024) of the Macau Science Satellite-1 (MSS-1). First, the Level 1b (L1b) magnetic data of the MSS-1 were processed, mainly including data selection and main magnetic field and external magnetic field corrections using the CHAOS-7.18 model. The SSA was then applied to the residual data of three selected nearest-neighbor orbits. The correlation study suggested that combining the second and third modes of the SSA decomposition was the optimal reconstruction strategy. Finally, the lithospheric signals were extracted from residual data of the MSS-1 by the SSA with the optimal parameters. Compared with the extraction results obtained by traditional and commonly used high-pass spherical harmonic filtering, our results showed a better noise reduction effect and were more consistent with the LCS-1 model predictions. In brief, this study proposed an approach to determine the optimal reconstruction parameters of the SSA and verified the effectiveness and applicability of utilizing the SSA to extract the lithospheric signals from satellite magnetic data.