Evaluation of GOCE-based global geopotential models versus EGM2008 and GPS/levelling data in northwest of Turkey

The Gravity field and steady-state Ocean Circulation Explorer (GOCE), reached the end of its mission in mid-October 2013, was a milestone in Earth’s gravity field determination. Several Global Geopotential Models (GGMs) have been published based on the data collected during the roughly 4-year mission of GOCE. This study focuses on evaluation of the contribution of GOCE data for the representation of gravity field with significant improved accuracy in Turkish territory. The evaluation is based on the consecutive releases as well as the releases generated by different computation strategies of GOCE-based models. In the study, a total of 7 GOCE-based models (EIGEN_6C3stat, JYY_GOCE02S, ITG-GOCE02, GO_CONS_GCF_2_TIM_Release 1, 2, 3, and 4) were assessed and the results were compared with the performance of EGM2008. The accuracy of GGMs was analyzed using the reference Global Positioning System (GPS)/levelling network of the case study for Bursa located in the northwest of the Anatolian peninsula. In the analysis, 433 GPS/levelling benchmarks after removing detected blunders were used for evaluation of the global geoid models. The validation results show the superior performance of the high resolution global combined model EIGEN_6C3stat among the evaluated models. Its fit with GPS/levelling-derived geoid heights in the study area is at the level of 9.1 cm in terms of the standard deviation of the differences.