Effect of crust density variation on gravimetric geoid determination

One of the most important goals of geodesy is to determine the geoid model with an accuracy of ±1 cm. This accuracy has not been achieved in many regions of world yet. This is partly due to the unknown density of the topographic masses of the regions. In general, the density value is taken as 2.67gr/cm³, which is a global average. However, the average density value differs from the actual density of the topographic masses by approximately %10 to %20 per cent. To achieve the optimum geoid accuracy mentioned above, it is necessary to take into account the density variation in the determining gravimetric geoid as well. One of the ways to achieve the density value is to use global, regional and local crust models. In this study, CRUST1.0 and EPCRUST models of the spherical earth crust models were used. The local density model produced for the region of interest is the most convenient way for the modeling the topographic masses. According to the previous studies, the effect of density on the geoid is significant particularly in mountainous regions. The density values obtained from global and regional models in our study area differs approximately ±%10 percent from the global average. It was investigated to what extent this difference affects gravimetric regional geoid determination in Konya Closed Basin. For this, 3 local geoids were determined by using 2.67 gr/cm³ value and density values obtained from spherical crust models, and the accuracy analysis of these geoids were analyzed with the help of GNSS-leveling data of the region.