Assessing the GOCE models accuracy in the Mediterranean area.

The GOCE satellite mission has significantly improved the results obtained with the previous satellite missions CHAMP and GRACE. Using GOCE data satellite Global Geopotential Models were developed using three different approaches, namely the direct, the time-wise and the space-wise approaches. The last releases of these models are complete to degree and order 300 (direct approach) and 280 (time-wise and space-wise approaches). In this paper, the different releases of the three estimation methodologies are compared with observed gravity and GPS/levelling data in the Mediterranean area and in particular, the Italian and Greek databases are considered. Comparisons are also carried out with respect to EGM2008 in order to check for possible improvements in the medium frequencies. For the validation of GOCE and GOCE/GRACE models, the spectral enhancement approach has been used, during which the models are augmented with EGM2008, up to its full degree of expansion, and terrain effects. These enhanced GOCE/GRACE geoid heights and gravity anomalies are then compared with the local data and statistics of the residuals have been computed. These comparisons show that significant improvements are obtained when Greek data are considered while the same doesn’t occur with the Italian data.