The Development of the Joint NASA GSFC and the National Imagery and Mapping Agency (NIMA) Geopotential Model EGM96
| dc.contributor.author | Lemoine, F. G. | |
| dc.contributor.author | Kenyon, S.C. | |
| dc.contributor.author | Factor, J.K. | |
| dc.contributor.author | Trimmer, R.G. | |
| dc.contributor.author | Pavlis, N. K. | |
| dc.contributor.author | Chinn, D.S. | |
| dc.contributor.author | Cox, C. M. | |
| dc.contributor.author | Klosko, S.M. | |
| dc.contributor.author | Luthcke, S.B. | |
| dc.contributor.author | Torrence, M.H. | |
| dc.contributor.author | Wang, Y. M. | |
| dc.contributor.author | Williamson, R.G. | |
| dc.contributor.author | Pavlis, Erricos C. | |
| dc.contributor.author | Rapp, R. H. | |
| dc.contributor.author | Olson, T. R. | |
| dc.date.accessioned | 2020-10-14T18:18:59Z | |
| dc.date.available | 2020-10-14T18:18:59Z | |
| dc.description.abstract | The NASA Goddard Space Flight Center (GSFC), the National Imagery and Mapping Agency (NIMA), and The Ohio State University (OSU) have collaborated to develop an improved spherical harmonic model of the Earth's gravitational potential to degree 360. The new model, Earth Gravitational Model 1996 (EGM96), incorporates improved surface gravity data, altimeter-derived gravity anomalies from ERS-1 and from the GEOSAT Geodetic Mission (GM), extensive satellite tracking data-including new data from Satellite Laser Ranging (SLR), the Global Postioning System (GPS), NASA's Tracking and Data Relay Satellite System (TDRSS), the French DORIS system, and the US Navy TRANET Doppler tracking system-as well as direct altimeter ranges from TOPEX/POSEIDON (T/P), ERS-1, and GEOSAT. The final solution blends a low-degree combination model to degree 70, a block-diagonal solution from degree 71 to 359, and a quadrature solution at degree 360. The model was used to compute geoid undulations accurate to better than one meter (with the exception of areas void of dense and accurate surface gravity data) and realize WGS84 as a true three-dimensional reference system. Additional results from the EGM96 solution include models of the dynamic ocean topography to degree 20 from T/P and ERS-1 together, and GEOSAT separately, and improved orbit determination for Earth-orbiting satellites. | en_US |
| dc.description.sponsorship | We acknowledge Dave Smith (NASA GSFC), Larry Kunz (NIMA), and Randy Smith (NIMA), who provided overall guidance and project management support. Muneendra Kumar (NIMA) provided inspiration and guidance during the early phases of the project. We acknowledge the support of personnel at NASA headquarters including Miriam Baltuck, who provided the funding necessary to see the NASA portion of the project through to completion. The authors acknowledge the contributions made by Frank Lerch of NASA GSFC, now retired, whose efforts over almost 30 years, and numerous publications significantly advanced the development of terrestrial and planetary gravitational models. We also acknowledge Girish Patel, who died shortly after the inception of this project following a long battle with cancer. Frank’s and Girish’s passion for their work and meticulous attention to detail continue to inspire us. The GEODYN and SOLVE support teams, including Dave Rowlands (NASA GSFC), and Despina Pavlis, John McCarthy, Scott Luthcke, Shelley Rowton, Shifang Luo, and Denise Moore at Raytheon STX, maintained the critical infrastructure upon which the processing of the satellite tracking data and the creation of the low-degree geopotential solutions depended. Without their valiant efforts, the EGM96 model would not exist. Andy Marshall, now at Lockheed Martin Denver, led the efforts to acquire TDRSS user tracking data and exploit the unique facets of this data type. We are grateful for his numerous technical contributions as well as his expert management of the TOPEX/POSEIDON precision orbit determination team at GSFC. Many of the satellite tracking and direct altimeter normal equations were created by Kenny Rachlin, now at Numerical Technologies Inc., who with long hours and valiant efforts always found a way to process vast quantities of data at an amazing rate. We acknowledge Bill Cunningham, who is currently with the Northrop Grumman Corporation Electronic Sensors and Systems Division, for his contributions over many months regarding the analysis of the elevation data, and the development of the project’s elevation models. Neader Chandler, Linda Gehrmann, and Sushila Kapoor (Raytheon STX) provided essential data processing support, and helped us to keep track of the hundreds of satellite tracking and altimeter normal equations. The authors acknowledge the following people at NIMA who made significant contributions to the joint project: Ken Burke, Richard Salman, Howard Small, Dennis Manning, Jim Davenport, Dennis VanHee, and Barb Wiley. Changyou Zhang at The Ohio State University (OSU) who worked with R.H. Rapp on the orthonormal Dynamic Ocean Topography evaluations. Chris Jekeli (OSU) made important suggestions related to the reduction and the analysis of the gravity data. The project is grateful for the efforts of the Special Working Group (SWG) led by Professor Michael Sideris of the University of Calgary. Their detailed reports and analyses of the preliminary models, influenced the final model selection and we encourage the reader to review the Bulletin of the International Geoid Service (IGeS Bulletin No. 6; e-mail: iges@ipmtf4.topo.polimi.it) which includes the reports of those who contributed to the evaluation of the project’s preliminary models. We acknowledge Steve Nerem, now at the University of Texas at Austin, and Joe Chan who played a significant role in the GSFC effort during the early half of the project. Many individuals and organizations around the world provided data, directly or indirectly to this project. Individuals who made vital contributions include: René Forsberg, Per Knudsen (KMS, Denmark); Seymour Laxon (University College London, UK); Dave McAdoo, and Dennis Milbert (NOAA, USA); Marc Véronneau (Geodetic Survey Division, Dept. Natural Resources, Canada), and Tilo Schoene (Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany). We acknowledge Bill Schreiner (UCAR, Boulder, Colorado, USA) for valuable discussions concerning the processing of the GPS/MET tracking data, and both Bill Schreiner (UCAR) and W. I. Bertiger (JPL) for making comparisons of GPS/MET orbits in advance of a GPS/MET project meeting held in Tucson, Arizona in February 1996. We acknowledge the NASA Center for the Computational Sciences (NCCS) at the Goddard Space Flight Center and especially Milt Halem, Nancy Palm, and Tom Schardt for their support. Our altimeter data, and satellite-only normal equations included between 8000 and 12000 parameters. The quantity of separate arcs and the size of the normal equations, taxed the storage and other operational aspects of the NCCS supercomputers. We are grateful for their patience and support throughout this project, and point out that without their facilities, the EGM96 model could not have been created. The authors acknowledge the CDDIS and the IGS for making tracking data available quickl1y, the French Space Agency (Centre National d’Etudes Spatiales, CNES) for the DORIS data to both TOPEX/POSEIDON and Spot-2. We thank Carey Noll (NASA GSFC) for hosting the EGM96 web page on the CDDIS (http://cddisa.gsfc.nasa.gov/926/egm96/egm96.html). Many figures in this report were created using Generic Mapping Tools (GMT), and we acknowledge the creators of this convenient software, P. Wessel (University of Hawaii at Manoa, Honolulu, Hawaii), and W.H.F. Smith (NOAA), for making GMT available to researchers around the world. | en_US |
| dc.description.uri | https://ntrs.nasa.gov/citations/19980218814 | en_US |
| dc.format.extent | 584 pages | en_US |
| dc.genre | technical reports | en_US |
| dc.identifier | doi:10.13016/m2upft-bhu5 | |
| dc.identifier.citation | F.G. Lemoine et al., The Development of the Joint NASA GSFC and the National Imagery and Mapping Agency (NIMA) Geopotential Model EGM96, https://ntrs.nasa.gov/citations/19980218814 | en_US |
| dc.identifier.uri | http://hdl.handle.net/11603/19890 | |
| dc.language.iso | en_US | en_US |
| dc.publisher | NASA | en_US |
| dc.relation.isAvailableAt | The University of Maryland, Baltimore County (UMBC) | |
| dc.relation.ispartof | UMBC Joint Center for Earth Systems Technology | |
| dc.relation.ispartof | UMBC Faculty Collection | |
| dc.relation.ispartof | UMBC Physics Department | |
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| dc.rights | Public Domain Mark 1.0 | * |
| dc.rights | This is a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law. | |
| dc.rights.uri | http://creativecommons.org/publicdomain/mark/1.0/ | * |
| dc.title | The Development of the Joint NASA GSFC and the National Imagery and Mapping Agency (NIMA) Geopotential Model EGM96 | en_US |
| dc.type | Text | en_US |