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Description:
The South America gravimetric geoid and quasi-geoid models, named SAM_GEOID2023 and SAM_QGEOID2023 respectively, encompass a latitude range from 15ºN to 58ºS and a longitude range from 99ºW to 32ºW, with a resolution of 5 arc minutes. A total of 959,930 terrestrial gravity values were utilized. The model was computed using the Meissl-modified Stokes kernel by Vaníček and Kleusberg (1987) with the SHGeo software package developed by the University of New Brunswick, Canada. The downward continuation process was applied. The global geopotential model XGM2019 up to degree and order 300 was employed to represent the reference gravity field long-wavelengths. The digital terrain model SRTMv3 was selected for the computation of topographical and atmospheric effects (referenced to the Earth and geoid surfaces), while the Grav_32.1 gravity field model was employed in oceanic regions. Because some countries in South America are based on normal height systems, the geoid model was converted to a quasi-geoid model using the classical geoid/quasi-geoid separation term by Heiskanen and Moritz (1967). The models were inferred by GNSS/levelling stations distributed in seven countries, with the difference standard deviation varying from 0.36 m in Ecuador to 0.07 in Uruguay.
Reference:
G.N. Guimarães, A.C.O.C. de Matos, D. Blitzkow (2024). El modelo geoidal para América del Sur (SAM_GEOID2023) y la conexión de los data verticales locales con IHRF. Presented at SIRGAS Symposium 2024, 18-21 November 2024, Bogotá, Colombia (in Spanish).
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