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.