Crossover analysis of BGI gravity datasets across Nigeria.

Abstract

The global gravity database of the Bureau Gravimetric International (BGI) has been used as a reliable source of gravity data for scientific inquiry and gravity field modeling by many countries, especially in regions with sparse terrestrial gravity data. However, considering the heterogeneity of the sources of the data in the BGI database, this study investigated the observational consistency of the BGI datasets over Nigeria. To that end, 4511 gravity data points covering Nigeria were collected from the BGI database and used in this study. The 4511 points were results of campaigns conducted by 15 different organizations at different times between 1938 and 1983. Taking the dataset obtained from the International Gravity Standardization Network 1971 (IGSN-71) as the control points, Crossover adjustment has been performed on all the existing datasets across the country for detection of observational inconsistencies in the datasets. Analysis of the Crossover adjustment at intersection points with the IGSN-71 datasets indicate high consistency of the dataset from British Antarctic survey, with values of -1.03 mgals, 2 mgals and 0.8 mgals in absolute gravity, free Air (FA) anomaly, and bouguer anomaly, respectively