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The Mexican gravimetric geoid: xGGM23

The gravimetric geoid model xGGM23 was computed at the University of New Brunswick, Canada, with the aim to update the national geoid for Mexico, as well as to contribute to the construction of the regional geoid for North and Central America. Terrestrial gravimetry collected up to year 2020 was processed in spectral combination with the satellite-derived geopotential model GOCO06s (up to degree and order 230) using the UNB’s Stokes-Helmert technique. The geoid model is purely gravimetric, corresponds to the regional standard reference gravity potential for North America (Wo=6263656.0 m2/s2), tide-free gravity concept, and covers latitudes from 10° N to 40° N and longitudes from 125° W to 80° W, with a grid resolution of 2.5 arc minutes. This resolution is coherent with the densification of terrestrial gravity data collected inside Mexico. The accuracy of geoidal height is estimated as 10 cm inside Mexico and 5 cm in the southern US. 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 Mexican gravimetric geoid: GGM10

GGM10 is a gravimetric geoid model for Mexico computed by the General Direction of Geography and Environment at the INEGI. It covers the region from 14° to 33° in latitudes and from 86° to 119° in west longitude, with a grid resolution of 2.5 arc-minutes. It is based on gravity data collected from 1970 up to June 2010. A remore-restore procedure is implemented by using the EIGEN-GRACE02S satellite-only global geopotential model for the long wavelengths of the field and the Continuo de Elevaciones Mexicano as the main digital terrain elevation model. The geoid determination is based on the Stokes-Helmert technique with the software provided by the University of New Brunswick (UNB). The resulting GGM10 model is referred to the GRS80 reference ellipsoid in the ITRF2008 frame (epoch 2010.0). Its estimated absolute accuracy in geoidal height values is 20 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 Mexican gravimetric geoid: GGM06

GGM06 is a gravimetric geoid model for Mexico calculated from a smaller but more reliable database of terrestrial gravimetry than the one used for its predecessor GGM05. The changes in geoidal height are mainly visible for the north-central territory of Mexico. The reference ellipsoid is GRS80, datum ITRF92 (epoch 1988.0). The input terrestrial gravity data consisted of nearly 30,000 points inside Mexico obtained from INEGI and US-DMA. Marine gravity was derived from Topex/Poseidon altimetry. The used digital terrain models were CEM1 and SRTM. A reference satellite geoid model was also used up to degree and order 40 from the GRACE geopotential model GGM02. The computation methodology was based on the Stokes-Helmert technique with the software provided by the University of New Brunswick (UNB), similar to the previous computation GGM05, but with an improved methodology for gravity data cleaning. The resulting GGM06 model is referred to the GRS80 reference ellipsoid in the ITRF92 frame (epoch 1988.0). The error RMS of geoidal heights is 35 cm, estimated from 1384 GPS/leveling data points. 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 Mexican gravimetric geoid: GGM05

GGM05 is the second gravimetric geoid model created by INEGI for Mexico with the main improvement of input data cleaning and the use of a more recent reference gravity field. It was computed by using a terrestrial gravity database of nearly 100,000 points inside Mexico and marine gravity derived from Topex/Poseidon altimetry. The used digital terrain models were Mexico-CEM1, US-NED and SRTM. A reference satellite geoid model was also used up to degree and order 40 from the GRACE geopotential model GGM02. The computation methodology was based on the Stokes-Helmert technique with the software provided by the University of New Brunswick (UNB). The resulting GGM05 model is referred to the GRS80 reference ellipsoid in the ITRF92 frame (epoch 1988.0). The error RMS of geoidal heights is 36 cm, estimated from 1384 GPS/leveling data points. 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 Mexican gravimetric geoid: GGM04

GGM04 is the first gravimetric geoid model for Mexico computed by INEGI on 2004 (GGM stands for Geoide Gravimetrico Mexicano). The main input of terrestrial gravity data included 100,000 points inside Mexico and nearly 400,000 more over neighboring countries, all unfiltered. The source for this dataset was INEGI, PEMEX and US-DMA. Marine gravity was derived from Topex/Poseidon altimetry. The used digital terrain models were Mexico-CEM1, US-NED and SRTM. A reference satellite geoid model was also used up to degree and order 40 from the geopotential model GRIM4-S4. The computation methodology was based on the Stokes-Helmert technique with the software provided by the University of New Brunswick (UNB, Canada). The resulting GGM04 model is referred to the GRS80 reference ellipsoid in the ITRF92 frame (epoch 1988.0). The error RMS of geoidal heights is 58 cm, estimated from 1377 GPS/leveling data. 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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