RIO2QG_FFT_2025 is a local, high-precision, high-resolution, pure-gravimetric quasigeoid model developed for the area surrounding RIO2, an International Height Reference Frame (IHRF) station located in the Province of Tierra del Fuego, Argentina, covering latitudes 56°S to 51°S and longitudes 71°W to 64°W, with a 0.03° grid resolution. The purpose of the model is to determine the IHRF vertical coordinate at this station. Its computation followed Molodensky’s formulation of the Geodetic Boundary Value Problem (GBVP) and employed the remove–compute–restore (RCR) strategy. Long-wavelength components were modeled using the XGM2019e Global Geopotential Model (GGM) up to degree and order 700. Topographic contributions were modeled via Residual Terrain Modeling (RTM) using the SRTM v4.1 Digital Elevation Model (DEM). Residual height anomalies were calculated with the 1D-FFT technique incorporating the Wong-Gore modification to Stokes’ kernel. All computational steps were performed with the GRAVSOFT software package. Validation against 41 GNSS/leveling points yielded an estimated precision of 0.061 m after applying a four-parameter fit. 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.
AGGOQG_FFT_2025 is a local, high-precision, high-resolution, pure-gravimetric quasigeoid model developed for the area surrounding AGGO and LPGS, two International Height Reference Frame (IHRF) stations located in the Province of Buenos Aires, Argentina, covering latitudes 36°S to 31°S and longitudes 61°W to 55°W, with a 0.03° grid resolution. The purpose of the modelis to determine the IHRF vertical coordinate at these stations. Its computation followed Molodensky’s formulation of the Geodetic Boundary Value Problem (GBVP) and employed the remove–compute–restore (RCR) strategy. Long-wavelength components were modeled using the XGM2019e Global Geopotential Model (GGM) up to degree and order 600. Topographic contributions were modeled via Residual Terrain Modeling (RTM) using the SRTM v4.1 Digital Elevation Model (DEM). Residual height anomalies were calculated with the 1D-FFT technique incorporating the Wong-Gore modification of Stokes’ kernel. All computational steps were performed with the GRAVSOFT software package. Validation against 111 GNSS/leveling points yielded an estimated precision of 0.063 m after applying a four-parameter fit. 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.
UNSAQG_FFT_2025 is a local, high-precision, high-resolution, pure-gravimetric quasigeoid model developed for the area surrounding UNSA, an International Height Reference Frame (IHRF) station located in the Province of Salta, Argentina, covering latitudes 26.5°S to 24.5°S and longitudes 66°W to 64°W, with a 0.03° grid resolution. The purpose of the model is to determine the IHRF vertical coordinate at this station. Its computation followed Molodensky’s formulation of the Geodetic Boundary Value Problem (GBVP) and employed the remove–compute–restore (RCR) strategy. Long-wavelength components were modeled using the XGM2019e Global Geopotential Model (GGM) up to degree and order 800. Topographic contributions were modeled via Residual Terrain Modeling (RTM) using the SRTM v4.1 Digital Elevation Model (DEM). Residual height anomalies were calculated with the 1D-FFT technique incorporating the Wong-Gore modification of Stokes’ kernel. All computational steps were performed with the GRAVSOFT software package. Validation against 51 GNSS/leveling points yielded an estimated precision of 0.124 m after applying a four-parameter fit. 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.
OAFAQG_FFT_2025 is a local, high-precision, high-resolution, pure-gravimetric quasigeoid model developed for the area surrounding OAFA and UNSJ, two International Height Reference Frame (IHRF) stations located in the Province of San Juan, Argentina, covering latitudes 34°S to 30°S and longitudes 70.5°W to 65.5°W, with a 0.03° grid resolution. The purpose of the model is to determine the IHRF vertical coordinate at these stations. Its computation followed Molodensky’s formulation of the Geodetic Boundary Value Problem (GBVP) and employed the remove–compute–restore (RCR) strategy. Long-wavelength components were modeled using the XGM2019e Global Geopotential Model (GGM) up to degree and order 840. Topographic contributions were modeled via Residual Terrain Modeling (RTM) using the SRTM v4.1 Digital Elevation Model (DEM). Residual height anomalies were calculated with the 1D-FFT technique incorporating the Wong-Gore modification of Stokes’ kernel. All computational steps were performed with the GRAVSOFT software package. Validation against 188 GNSS/leveling points yielded an estimated precision of 0.170 m after applying a four-parameter fit. 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.
UNPAQG_FFT_2025 is a local, high-precision, high-resolution, pure-gravimetric quasigeoid model developed for the area surrounding UNPA, an International Height Reference Frame (IHRF) station located in the Province of Santa Cruz, Argentina, covering latitudes 54°S to 50°S and longitudes 72°W to 66°W, with a 0.03° grid resolution. The purpose of the model is to determine the IHRF vertical coordinate at this station. Its computation followed Molodensky’s formulation of the Geodetic Boundary Value Problem (GBVP) and employed the remove–compute–restore (RCR) strategy. Long-wavelength components were modeled using the XGM2019e Global Geopotential Model (GGM) up to degree and order 740. Topographic contributions were modeled via Residual Terrain Modeling (RTM) using the SRTM v4.1 Digital Elevation Model (DEM). Residual height anomalies were calculated with the 1D-FFT technique incorporating the Wong-Gore modification of Stokes’ kernel. All computational steps were performed with the GRAVSOFT software package. Validation against 81 GNSS/leveling points yielded an estimated precision of 0.092 m after applying a four-parameter fit. 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.
The Uruguayan gravimetric geoid model UruGeoide110 was calculated by the Military Geographic Institute (IGM) in 2023. The extent is from 29.5° S to 35.5° S in latitude, and 52.5° W to 59.5° W in longitude, covering parts of Argentina and Brazil, with a grid resolution of 1´ x 1´. The geodetic reference system is SIRGAS ROU-98 (the reference ellipsoid is GRS80). The model is a combination of the EIGEN-6C4 geopotential model up to degree and order of 720, 10,429 land gravimetric stations plus 10,089 free air gravity anomalies in marine areas, based on the DTU13 model. The terrain data at the final 90 m resolution was taken from a 2017 Lidar survey in Uruguay with a 2.5 m initial resolution and SRTM (V2) for the external terrestrial data. The DT18 bathymetry model was used for the marine areas. Due to the total terrain data points (about 104 million), the overall area was divided into 4 overlapped blocks in the framework of the remove-compute-restore procedure. The reduced height anomalies were computed from the reduced gravity anomalies with Stokes 1D FFT and Wong Gore´s kernel modification (170-180 degrees). After adding back the residual terrain model effects and the contribution of the global geopotential model, the obtained quasi-geoid was transformed into a geoid model via Bouguer anomalies, even if the difference between the two models is just a few mm. A comparison with 51 GNSS/levelling stations shows a standard deviation of 10 cm. 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.
The Uruguayan gravimetric quasi-geoid model UruQGeoide110 was calculated by the Military Geographic Institute (IGM) in 2023. The extent is from 29.5° S to 35.5° S in latitude, and 52.5° W to 59.5° W in longitude, covering parts of Argentina and Brazil, with a grid resolution of 1´ x 1´. The geodetic reference system is SIRGAS ROU-98 (the reference ellipsoid is GRS80). The model is a combination of the EIGEN-6C4 geopotential model up to degree and order of 720, 10,429 land gravimetric stations plus 10,089 free air gravity anomalies in marine areas, based on the DTU13 model. The terrain data at the final 90 m resolution was taken from a 2017 Lidar survey in Uruguay with a 2.5 m initial resolution and SRTM (V2) for the external terrestrial data. The DT18 bathymetry model was used for the marine areas. Due to the total terrain data points (about 104 million), the overall area was divided into 4 overlapped blocks in the framework of the remove-compute-restore procedure. The reduced height anomalies were computed from the reduced gravity anomalies with Stokes 1D FFT and Wong Gore´s kernel modification (170-180 degrees) and the quasi-geoid model was finally obtained by adding back the residual terrain model effects and the contribution of the global geopotential model. 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.
The official Uruguayan geoid model, called IGM110, was calculated by the Military Geographic Institute (IGM) in 2023 and consists of a grid of 1´ x 1´ geoidal undulations with a total of 151,981 points. The geodetic reference system is SIRGAS ROU-98 (the reference ellipsoid is GRS80). The extent is from 29.5° S to 35.5° S in latitude, and 52.5° W to 59.5° W in longitude, covering parts of Argentina and Brazil. The model is a combination of the EIGEN-6C4 geopotential model up to degree and order of 720, 10,429 land gravimetric stations plus 10,089 free air gravity anomalies in marine areas, based on the DTU13 model. The terrain data at the final 90 m resolution was taken from a 2017 Lidar survey in Uruguay with a 2.5 m initial resolution and SRTM (V2) for the external terrestrial data. The DT18 bathymetry model was used for the marine areas. Due to the total terrain data points (about 104 million), the overall area was divided into 4 overlapped blocks in the framework of the remove-compute-restore procedure. The reduced height anomalies were computed from the reduced gravity anomalies with Stokes 1D FFT and Wong Gore´s kernel modification (170-180 degrees). After adding back the residual terrain model effects and the contribution of the global geopotential model, the obtained quasi-geoid was transformed into a geoid model via Bouguer anomalies, even if the difference between the two models is just a few mm. A comparison with 51 GNSS/levelling stations shows a standard deviation of 10 cm. The resulting geoid was also adapted by a bias and a tilt to the national vertical system, Cabildo 1948, by fitting GNSS/levelling observations, with a mean of 1 cm and a standard deviation of 7 cm. 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.
The ColFFTWG2020 quasi-geoid model is a gravimetric model and has been computed by the Laboratory of Gravity Field Research and Applications, Aristotle University of Thessaloniki. The model has been computed in the frame of the International Association of Geodesy Joint Working Group 2.2.2 "The 1 cm geoid experiment" and the so called "Colorado experiment". The area covered by the models is 108.5°E ≤ longitude ≤ 103.5°E, 36.5°N ≤ latitude ≤ 38°N with a grid spacing of 2' in both latitude and in longitude. The computation is based on the remove-compute-restore technique with XGM2106 being used as a reference field. The topographic effects were treated using a Residual Terrain Correction (RTC) by solving the spectral filter problem of RTC using Earth2014 and ERTM2160 models. The input gravity data include terrestrial and airborne data combined using Least-Squares Collocation (LSC). The final estimation was carried out using 1D FFT with Wong-Gore modification of the Stokes kernel. The accuracy of the model, when compared against GSVS17 GPS/leveling, is at 2.5 cm level. 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.
The ColFFTWG2020 quasi-geoid model is a gravimetric model and has been computed by the Laboratory of Gravity Field Research and Applications, Aristotle University of Thessaloniki. The model has been computed in the frame of the International Association of Geodesy Joint Working Group 2.2.2 "The 1 cm geoid experiment" and the so called "Colorado experiment". The area covered by the models is 108.5°E ≤ longitude ≤ 103.5°E, 36.5°N ≤ latitude ≤ 38°N with a grid spacing of 2' in both latitude and in longitude. The computation is based on the remove-compute-restore technique with XGM2106 being used as a reference field. The topographic effects were treated using a Residual Terrain Correction (RTC) by solving the spectral filter problem of RTC using Earth2014 and ERTM2160 models. The input gravity data include terrestrial and airborne data combined using Least-Squares Collocation (LSC). The final estimation was carried out using 1D FFT with Wong-Gore modification of the Stokes kernel. The mean accuracy of the model, when compared against GSVS17 GPS/leveling, is at 1.6 cm level. 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.
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