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.