Validation of GOCE Gravity Data, Using Terrestrial Observed Gravity Anomalies Over Enugu State, Nigeria

Gravity Recovery and Ocean Circulation Explorer (GOCE) is one of the gravity data that can be used for the determination of gravity field parameters such as the deflection of the vertical component, geoid height etc. GOCE mission was aimed at measurement of gravity field anomalies with accuracy of 10-2ms-2 and to determine the geoid with an accuracy of 1-2cm.The use of this GOCE data in an area, just like any other global geo-potential model (GGM) will depend on its fit to the terrestrial observed values. The main thrust of this paper is to validate GOCE data over terrestrial observed gravity anomalies for one hundred and fifteen points where bouguer gravity anomaly has been computed over Enugu State in Nigeria. The computed gravity anomaly obtained using the GOCE data was compared to the one obtained terrestrially for the entire points. The maximum and minimum difference was 0.064768m/gal and 29.62059m/gal. The root mean square error is 13.79396, 14.42247 and 13.09670 for the different epochs R3, R4, R5 respectively. It was found that GOCE derived gravity values cannot be used in Nigeria to represent point values because it has a long wavelength of measurement. It may however be considered for a reference for geoid computation where it takes care of the long wavelength as part of the gravity field.