Investigation of Geoid Height Variations and Vertical Displacements of the Earth Surface in the Context of the Realization of a Modern Vertical Reference System: A Case Study for Poland

The GRACE (Gravity Recovery and Climate Experiment) mission launched in 2002 brought a unique opportunity for the determination of temporal mass variations within the Earth system. Their knowledge is essentially needed to achieve the best accuracy of a regional/local geoid model. They are also needed to investigate temporal displacements of the physical surface of the Earth. The aim of this contribution is to study temporal variations of geoid heights as well as to discuss the vertical displacements of the Earth surface in the perspective of the realization of the modern vertical reference system. The area of Poland has been chosen as a study area. Temporal geoid height variations have been determined over the area of Poland divided into four subareas. They have been analysed and modelled using the seasonal decomposition method. As an example, temporal vertical displacements induced from temporal water variations at the Borowa Gora Observatory (BGO) have been determined using GRACE mission data. The results obtained in a case study for Poland reveal that the combination of temporal geoid height variations and temporal vertical displacements of the physical surface of the Earth result in significant temporal variations of the vertical reference system for the area investigated.