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Gravity model development for TOPEX/POSEIDON: Joint gravity models 1 and 2The TOPEX/POSEIDON (T/P) prelaunch Joint Gravity Model-1 (JGM-1) and the postlaunch JGM-2 Earth gravitational models have been developed to support precision orbit determination for T/P. Each of these models is complete to degree 70 in spherical harmonics and was computed from a combination of satellite tracking data, satellite altimetry, and surface gravimetry. While improved orbit determination accuracies for T/P have driven the improvements in the models, the models are general in application and also provide an improved geoid for oceanographic computations. The postlaunch model, JGM-2, which includes T/P satellite laser ranging (SLR) and Doppler orbitography and radiopositioning integrated by satellite (DORIS) tracking data, introduces radial orbit errors for T/P that are only 2 cm RMS with the commission errors of the marine geoid for terms to degree 70 being +/- 25 cm. Errors in modeling the nonconservative forces acting on T/P increase the total radial errors to only 3-4 cm root mean square (RMS), a result much better than premission goals. While the orbit accuracy goal for T/P has been far surpassed geoid errors still prevent the absolute determination of the ocean dynamic topography for wavelengths shorter than about 2500 km. Only a dedicated gravitational field satellite mission will likely provide the necessary improvement in the geoid.
Document ID
19950049098
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Nerem, R. S. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lerch, F. J. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Marshall, J. A. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Pavlis, E. C. (Univ. of Maryland, College Park, MD United States)
Putney, B. H. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Tapley, B. D. (Univ. of Texas, Austin, TX United States)
Eanes, R. J. (Univ. of Texas, Austin, TX United States)
Ries, J. C. (Univ. of Texas, Austin, TX United States)
Schutz, B. E. (Univ. of Texas, Austin, TX United States)
Shum, C. K. (Univ. of Texas, Austin, TX United States)
Date Acquired
August 16, 2013
Publication Date
December 15, 1994
Publication Information
Publication: Journal of Geophysical Research
Volume: 99
Issue: C12
ISSN: 0148-0227
Subject Category
OCEANOGRAPHY
Distribution Limits
Public
Copyright
Other