Gravimetric densification in the state of São Paulo aiming a geoid model

Abstract

Gravitydata coverage is quite complete in São Paulo state for a 5' resolution. In addition, field works have been conducted to fill in gaps around the state. These efforts are the results of the Fundação de Amparo 'a Pesquisa do Estado de São Paulo (FAPESP) Thematic Project that seeks to achieve the establishment of a geoid model, a height system, and the study of mean sea level. This paper presents a comparison between two geoidal height models; the first with information available up to 2008 (beginning of the project) and the second including all data collected. Both models have been derived using the modified Stokes integral through the FFT technique. The SHGEO package was used to derive the Helmert gravity anomalies, while the EGM2008 model was selected as a reference geopotential field restricted to degree and order 150, to obtain the long and medium wavelength components. The model was validated using the geoidal heights from 170 GPS observations on Bench Marks of the spirit leveling network. The corresponding height anomalies derived from recent geopotential models (GO CONS GCF 2 TIM R2, GOCO02S and EIGEN-6C) were also compared with the same quantities at the points of leveling, besides the official Brazilian model, MAPGEO2010. The findings showed that GEOIDSP2011 displayed better consistency with respect for the GPS/leveling than GEOIDSP2008 and the geopotential models. © 2013 Sociedade Brasileira de Geofísica.