Monitoring of Antarctic Crustal Movement Based on Precise Point Positioning with Ambiguity Resolution Method

Abstract High-precision monitoring of crustal motion in Antarctica is of great significance for investigating mass changes of the Antarctic Ice Sheet (AIS), environmental loading effects, and regional geodynamic processes. Precise Point Positioning (PPP) is an effective positioning technique in environments where reference stations are sparse, and PPP Ambiguity Resolution (AR) has clear advantages over float PPP. In this study, PPP and PPP-AR were respectively applied to process the combined Global Positioning System (GPS) and Galileo observations from eight Multi-Global Navigation Satellite System Experiment (MGEX) reference stations in Antarctica during 2020–2024, thereby obtaining long-term coordinate time series, and wavelet analysis, outlier detection, and time-series reconstruction were utilized to improve the quality of the coordinate time series. Based on the pre-processed coordinate time series, the horizontal velocity field was estimated utilizing least-squares linear fitting, and an Antarctic Plate motion model was constructed based on the rigid plate rotation assumption and Euler vector parameters. The results show that, compared with float PPP, PPP-AR can effectively reduce abnormal jumps and random fluctuations in the coordinate time series. Moreover, PPP-AR improves the average positioning accuracy in the North and East components by 7.80% and 24.65%, respectively. In addition, PPP-AR also improves the accuracy of horizontal velocity estimation, with improvements of 20.00% in the North component and 33.33% in the East component. The Euler vector model constructed utilizing six MGEX reference stations was validated with two stations that were not involved in the modeling, and the velocity differences are generally at the millimeter level. The estimated Euler vector parameters are also in good agreement with those of the International Terrestrial Reference Frame 2020 Velocity Model (ITRF2020VEL). In conclusion, compared with float PPP, PPP-AR can effectively improve the quality of coordinate time series and the accuracy of horizontal velocity estimation for Antarctic stations, and can provide a methodological reference for Antarctic plate motion analysis and crustal deformation monitoring.