Evaluation of global gravity field models using shipborne free-air gravity anomalies over the Gulf of Guinea, Central Africa

In this work, the principal aim is to evaluate some recent GGMs on the Gulf of Guinea region using shipborne free-air gravity data. Two types of GGMs are evaluated in this study: combined models (EGM2008, EIGEN-6C4, GECO, SGG-UGM-1, GOCO05C and XGM2016) and satellite-only models (DIR_R5, ITU_GGC16, SPW_R5, TIM_R5, GGM05G and NULP_02S). The comparisons between these GGMs and the preliminary filtered shipborne gravity data were performed before and after the Spectral Enhancement Method (SEM). The statistical results have shown that the combined models have a better performance than the satellite-only models. Before and after SEM, we note that the EGM2008 model presents the best statistical results compared to the shipborne gravity anomalies (RMS and SD values respectively changes from 3.87 to 3.55 mGal and from 3.57 to 3.32 mGal). However, the DIR_R5 model is the best of the satellite-only GGMs of this study.