Comparative analysis of the impact of different environmental loading products on contemporary vertical land motion of mainland China from multigeodetic measurements

SUMMARY The elastic deformation of Earth’s surface caused by internal mass distribution varies significantly across loading models, especially in high-precision applications. Although several studies have applied loading corrections to Global Navigation Satellite System (GNSS) time-series in mainland China, discrepancies between models, particularly those involving Gravity Recovery and Climate Experiment (GRACE) data and its downscaled derivatives, remain insufficiently explored. Moreover, previous research has not comprehensively assessed vertical crustal deformation after applying different environmental loading corrections. This study systematically evaluates the correction effects of various environmental loading models on GNSS vertical displacements across mainland China, generating vertical velocity maps along with their associated uncertainties. The results show that hydrological loading (HYDL) has the most significant impact on GNSS vertical displacements, whereas non-tidal oceanic loading (NTOL) has the least effect. Substantial differences exist between various HYDL models, while discrepancies between non-tidal atmospheric loading and NTOL models are relatively minor. A comparison of correction effects between the HYDL model and GRACE data reveals that the HYDL model offers more accurate corrections, whereas downscaled GRACE data demonstrates improved performance, underscoring its potential advantages. After applying loading corrections and filtering common mode error, the uncertainty in GNSS vertical velocity is notably reduced, although velocity variation remains small. This effect is also evident in seasonal variations. Furthermore, a comparison of vertical land motion (VLM) constrained by different HYDL models and downscaled GRACE data with VLM constrained by an independent land–water fusion model reveals higher consistency between the downscaled GRACE data and the independent model in the North China and northwestern Tianshan regions, suggesting that VLM derived from downscaled GRACE data may be more reliable. We also quantify the combined impact of geocentre motion and glacial isostatic adjustment on the VLM trend across mainland China, estimated it at approximately 0.13 mm yr−1. While the spatial characteristics of the VLM trend show minimal changes after correction, its intensity is significantly affected. This study provides crucial insights into the correcting of environmental loading effects in GNSS vertical displacements and contributes the latest observational results on vertical crustal deformation in mainland China.