Banda Arc Geophysics

Earth Gravitational Model EGM2008 from the NGA

Summary

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.

 

EGM2008 Free-air gravity anomaly 3D image 203kb EGM2008 free-air gravity anomaly 3D image.
EGM2008 Total Deflection of the Vertical (DOV) 3D image 364kb EGM2008 Total Deflection of the Vertical (DOV) 3D image.
1917kb EGM2008 vector map of the DOV (deflections of the vertical).
EGM2008 coloured map of vector angles for the DOV. 405kb EGM2008 coloured map of vector angles for the DOV.
EGM2008 shaded coloured map of vector angles for the DOV. 346kb EGM2008 shaded coloured map of vector angles for the DOV.
EGM2008 coloured map of vector magnitudes for the DOV 190kb EGM2008 coloured map of vector magnitudes for the DOV.
EGM2008 shaded coloured map of vector angles for the DOV overlain by NEIC earthquake locations, colour coded for depth 939kb EGM2008 shaded coloured map of vector angles for the DOV overlain by NEIC earthquake locations, colour coded for depth.

Steve Kaye. Protected under UK and international law. May be used free of charge. Selling without prior written consent prohibited. Obtain permission before redistributing. In all cases this notice must remain intact.