Estimation of physical height changes from GRACE satellite mission data and WGHM over Turkey

Gravity Recovery and Climate Experiment (GRACE) satellite mission had provided gravity data for ca. 15 years, completed its mission in 2017 and handed over to GRACE Follow-On. During its active life, GRACE contributed to the understanding of temporal variations of geoid/quasigeoid heights as well as vertical and horizontal displacements of the Earth’s surface induced by mass loading, and thereby the physical height (e.g. the orthometric/normal height) changes. The main objective of this research is to estimate physical height changes over the area of Turkey. The release 6 GRACE-based global geopotential models and WaterGAP (Water—a Global Assessment and Prognosis) Global Hydrology Model products as well as load Love numbers from the Preliminary Reference Earth Model were used as input data. Physical height changes over Turkey were estimated using three different approaches: the GRACE-based Global Geopotential Models, the Green’s function, and the Terzaghi’s principle. The estimated physical height changes were analysed and modelled by means of the seasonal decomposition method and the Principal Component Analysis/Empirical Orthogonal Function method. The main findings reveal that physical height changes over Turkey reach the level of a few centimetres during years 2004–2010.