Robust network adjustment of vertical movements with GNSS data

Long operation periods of GNSS stations give a possibility to use the data in analyzing vertical crustal movements with the accuracy better than ± 0.5 mm/y. During the analysis, the reliability must be considered. This involves the choice of the vertical crustal movements network adjustment method. In most cases, the vertical crustal movements network models are designed as absolute and related to the ellipsoid, where the movement is calculated on the basis of estimated station coordinates. The other option is choosing differential relative models, where GNSS vector coordinates are used. In this case, GNSS stations are connected and vertical movements between them are calculated. In the next stage, the network of vertical crustal movements is adjusted and the accuracy is assessed. The aim of this article is to calculate and adjust the unadjusted trend based on GNSS time series in an area located in Central Europe. The article presents the robust adjustment method with a weighting scheme. The obtained results show that the accuracy of vertical crustal movements model of 0.5 mm/y can be obtained from the GNSS observations processing. Also the benefits coming from the application of robust adjustment method are emphasized.