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Earth Gravity Model

The Geosciences Division provides the normalized, geopotential coefficients for both the new NGA/NASA EGM96 n=m=360 and the WGS 84 n=m=180 Earth Gravitational Model. It also provides two geoid products, the 15-minute, worldwide geoid height file for EGM96 and the 30-minute worldwide geoid height file for the original WGS 84 model. Both the EGM96 and the WGS 84 geoid height files and coefficient files have associated software and documents. They are available for unlimited distribution. The NGA/NASA 15-minute worldwide geoid height file and the WGS 84, n=m=360, EGM96 coefficient file are approved for official DOD use as documented in NGA TR8350.2, Third Edition, 4 July 1997. The 30-minute geoid height file and the WGS 84, n=m=180, EGM coefficient file described on the WGS 84 (180,180) web pages are approved for DOD use as documented in DMA TR8350.2, Second Edition, 1 September 1991.

We are currently in the process of the final re-iteration of our modeling and estimation approach, and expect to have the final model completed in time for the upcoming General Assembly of the European Geosciences Union, to be held in Vienna, Austria, 13-18 of April 2008. During this meeting we plan to present and make our final model publicly available to all.

 Product Search Sites

NGA WGS 84 Earth Gravitational Model
EGM2008 Status Update, Background Papers from Recent Symposiums on the New EGM, EGM Harmonic Synthesis Software and "Test" Coefficient Sets, EGM96 (360, 360), EGM96 15' x 15' Geoid Undulation Plot, METADATA - EGM96 EARTH GRAVITATIONAL MODEL, EGM84 (180, 180)

 Additional Information and Resources

Earth Gravity Model
NGA is responsible for collecting, processing, and evaluating gravity data (free-air and Bouguer gravity anomalies).