Reprocessing of three-decade GNSS observations: millimeter-level nonlinear terrestrial reference frame, global velocity field and plate motion model refinement

The Terrestrial Reference Frame (TRF) is essential for solid Earth research, including geodesy and geodynamics, providing a unified spatiotemporal datum. With the continuous expansion of global GNSS infrastructure and data, significant progress has been made in refining TRF and models of crustal plate motion and tectonic deformation. This study provides a global velocity field and a plate motion model through three decades of Global Navigation Satellite System (GNSS) data and nonlinear TRF refinement. Key contributions include: (1) the Integrated and Improved Time Series Analysis (IITSA) model, achieving horizontal fitting precision of 3 mm and vertical precision of 6 mm for three-decade GNSS time series; (2) the Global GNSS Velocity Model 2020 (GGVM2020), with RMS values of 0.12, 0.11, and 0.26 mm/yr in the north, east, and up directions, providing new insights into the crustal movements of Antarctica and North America; (3) the Global Interpolation Velocity Model 2020 (GIVM2020), offering a global horizontal velocity grid (3°×3°) with interpolation accuracy better than 3 mm/yr, enabling velocity estimation for any site globally; and (4) the Global Plate Motion Model 2020 (GPMM2020), which improves the accuracy of Euler motion parameters for the 14 major tectonic plates, achieving precision better than 3 mm/yr. In conclusion, the study’s results, including the global GNSS velocity field and plate motion model, enhance the reliability and application of terrestrial reference frame products.