The gravimetric geoid of São Paulo State: GEOID-SP-2020-GGM720

The geoid model of São Paulo State was computed using the updated and filtered gravimetric data and the new system of the normal height of the 2018 Brazilian Vertical Reference Frame (BVRF). For the ocean area, gravity anomalies of the DTU13 model with a resolution of 1’ were used. To quantify the terrain effects through the Residual Terrain Model procedure, the SRTM15+ DTM was used. The computation of the quasi-geoid model was performed by numerical integration through the Fast Fourier Transform (FFT). The Molodensky gravity anomaly was determined in a 5’x5’ grid and reduced and restored using the Residual Terrain Model (RTM) technique and the XGM2019e global gravity model truncated at degree and order 720. The geoid model was derived from the Bouguer gravity anomalies. The zero-order degree term was added in the final computation. The validation for the quasi-geoid model based on 291 GPS measurements in the leveling network has shown 18 cm RMS difference. The geoid model is provided in ISG format 2.0 (ISG Format Specifications), while the file in its original data format is available at the model ISG webpage.