Earth Gravitational Model EGM2008 from the NGA
The Office of GEOINT Services, of the National Geospatial Intelligence (NGA), released in January 2009 a global dataset of free-air anomaly gravity data and Deflections of the Vertical (DOV) computed from EGM2008.
EGM2008 is the NGA's official Earth Gravitational Model complete to spherical harmonic degree and order 2159, and contains additional coefficients extending to degree 2190 and order 2159.
All computations for the free-air and DOV data were performed using the Tide-Free version of EGM2008 to degree 2190. The WGS 84 Geodetic Reference System (GRS) was used to define the geometry and the normal gravitational potential of the reference ellipsoid.
Further details are available on the NGA website. The images below have been produced from the original 2.5x2.5 minute NGA grids.