Characterizing the seasonal loading deformation in North China using GNSS and surface loading models

The North China (NC) has suffered irreversible land subsidence in specific regions as a result of groundwater storage depletion.Investigating the influence of surface mass loading on seasonal deformation is essential for isolating accurate tectonic deformation linked to uplift and subsidence.This study utilized data from the Global Navigation Satellite System (GNSS) and Surface Loading Models (SLM) derived from the German Research Centre for Geosciences (GFZ) and the International Mass Loading Service (IMLS), covering the period from January 2011 to March 2023, to investigate the impacts of hydrological loading (HYDL), atmospheric loading (ATML), and non-tidal ocean loading (NTOL) on seasonal deformation in NC.The results indicated that the average root mean square (RMS) reduction value was -2.74 %, 5.9 %, and 1 % after deducting the deformation attributed to HYDL, ATML, and NTOL based on GFZ, respectively.Conversely, the average RMS reduction value from IMLS was 0.99 %, 5.6 %, and 1 %, respectively.Furthermore, the average annual amplitudes and phases in the seasonal deformations induced by ATML and GNSS time series were 4.7 mm and 175°, and 4.6 mm and 138°, respectively, indicating that the ATML can serve as a principal driving force for GNSS seasonal deformation in comparison of HYDL and NTOL.Additionally, we assessed the effect of surface mass loading on velocity and its uncertainty estimated from GNSS time series using the combination of white noise and flicker noise models, the results demonstrated that the average velocity and its uncertainty was 0.04 mm/a before and after SLM correction, revealing that that surface mass loading has a negligible influence on velocity and its uncertainty in NC.