EGM96: The NASA GSFC and NIMA Joint Geopotential Model

NASA/TP-1998-206861 describes the development of the model in detail, and is available to interested researchers and scientists.

Table of contents:

Chapter 1. Introduction (3 pages).

Chapter 2. The development of the Global Topographic Data Base JGP95E (30 pages).

Chapter 3. The surface gravity data (32 pages).

Chapter 4. The altimeter derived anomalies (28 pages).

Chapter 5. Model evaluation techniques and data (35 pages).

Chapter 6. Estimation of the geopotential model implied by the satellite tracking data (171 pages).

Chapter 7. The comprehensive low-degree combination model (86 pages).

Chapter 8. The estimation of the high-degree geopotential models (83 pages).

Chapter 9. The preliminary geopotential models and their evaluation by the SWG (3 pages).

Chapter 10. The selection of the EGM96 geopotential model (50 pages).

Chapter 11. The egm96 geoid undulation with respect to the WGS84 ellipsoid. (6 pages).

Chapter 12. Summary (8 pages).

The final version of our Tokyo proceedings paper is now available. The paper has been published by Springer-Verlag, and the full reference is as follows:

The Development of the NASA GSFC and NIMA Joint Geopotential Model,
F. G. Lemoine, D. E. Smith, L. Kunz, R. Smith, E. C. Pavlis, N. K. Pavlis, S. M. Klosko, D. S. Chinn, M. H. Torrence, R. G. Williamson, C. M. Cox, K. E. Rachlin, Y. M Wang, S. C. Kenyon, R. Salman, R. Trimmer, R. H. Rapp, and R. S. Nerem,
IN: Gravity, Geoid and Marine Geodesy, Vol. 117, International Association of Geodesy Symposia, J. Segawa, H. Fujimoto, and S. Okubo (editors), pp 461-469, 1997.

Click here to download a postscript version of the Tokyo paper, 66.4 kbytes.

The EGM96 Tidal Solution

Some of you have asked about the EGM96 tidal solution. The low-degree (to degree 70) portion of the solution also included an adjustment for 12,000 parameters, including the geopotential coefficients to degree 70, 112 tidal coefficients, pole position from 1980 to 1994, station coordinates, and coefficients of the dynamic ocean topography (DOT) for TOPEX/ERS-1 and GEOSAT to degree and order 20.

Click here to view a synopsis of the tidal solution, extracted from the EGM96 Technical Report.

EGM96 Geoid Grid Available!!!

A geoid grid based on the EGM96 geopotential model, on a 0.25 x 0.25 degree grid is available from the National Geospatial-Intelligence Agency (NGA, formerly NIMA). This grid includes the height anomaly correction terms, which can attain 3.4 meters in the Himalayas, and smaller but significant values in other mountainous areas. Note that this geoid grid is in the tide-free (not the mean tide!!) system.

Click here to go to the NGA web page on EGM96, and retrieve the geoid grid.

Please see Rapp [1996], for a discussion of the height anomaly/geoid undulation difference.

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Last updated June 17, 2005 18:13 UTC.