The first high-resolution gravimetric geoid for the Bolivian tableland: BOLGEO

The new gravimetric geoid presented in this paper is calculated in the Bolivian tableland, South America. This geoid is of great importance because there are a few geoid solutions in South America. In the Bolivian tableland, the geoid was computed using the most advanced techniques and recent available database, including the most accurate satellite, land and marine data. Therefore, this geoid is getting more accuracy and reliability than the global geoid EIGEN-CG01C and acts as an excellent contribution to the geodesy and gravity studies in South America. The Stokes integral convolution method was used in the computation and showed great efficiency. The terrain correction was applied for the gridded gravity data, using the digital terrain model database supplied by SRTM 90M (Shuttler Radar Topography Mission). Also, the indirect effect has been taken to account. This new geoid covers the Bolivian tableland area, from latitude 23 to 15 S and longitude 70 to 65 W (5 × 8°), in the form of a 201 × 321 regular grid of mesh size of 1.5′ × 1.5′ (64521 points) in the GRS80 reference system. This gravimetric geoid and the EIGEN-CG01C geoid are compared to the geoid undulations corresponding to 17 GPS/levelling points, located in the study area. This new geoid shows an improvement in precision and reliability, fitting the geoidal heights of these 17 validation points, with more accuracy than the global geoid. This is because a global geoid model can fail to fit the observed data, especially in regions with very rugged topography such as our study area. This new model will be useful for geodetic height determination by GPS over the Bolivian tableland, because it allows the orthometric height determination in the mountains and remote areas, in which the levelling has many logistic problems. This new model also can be interesting for geophysical purposes, different to the geodesy and the heights measurements. This geoid is an important contribution to Geophysics, because it can provide a constraint for density distribution, thermal state of the lithosphere and viscosity in the mantle. Such details can be inferred from the geoid and the seismic structure of the study area.