Analyzing the 3D Deformation Induced by Non-tidal Loading in GNSS Time Series in Finland

Improving our understanding of non-tidal loading (NTL) in geodetic time series, especially at regional and local scales, holds paramount importance. This deeper comprehension enables accurate modeling and effective removal of NTL effects from the time series, consequently enhancing the overall stability and reliability of geodetic observations. In this study, we compared the performance of different loading products and investigated their impact on the 20-year time series of four permanent GNSS stations within the Finnish permanent GNSS network (FinnRef). We employed original GNSS time series data products generated by four different analysing centers. We qualitatively compared NTL corrections involving ten different combinations of different hydrological, non-tidal atmospheric, and non-tidal oceanic loading models to see how various loading configurations operate and how they affect the noise characteristics of GNSS 3D time series, and ultimately to figure out which models are the most realistic in Finland. We observed weighted RMS reduction rates of up to 20% for the vertical coordinate and up to 10% for the horizontal coordinate. Additionally, we identified a maximum annual amplitude reduction rate of 87.2%. The results demonstrate a substantial improvement through the integration of hydrological loading products derived from GRACE satellites in our study conducted over Finland.