Gravity model development for TOPEX/POSEIDON: Joint Gravity Models 1 and 2 Journal Article uri icon



  • The TOPEX/POSEIDON (T/P) prelaunch Joint Gravity Model‐1 (JGM‐I) 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 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.

publication date

  • December 15, 1994

has restriction

  • closed

Date in CU Experts

  • April 18, 2014 4:27 AM

Full Author List

  • Nerem RS; Lerch FJ; Marshall JA; Pavlis EC; Putney BH; Tapley BD; Eanes RJ; Ries JC; Schutz BE; Shum CK

author count

  • 20

Other Profiles

International Standard Serial Number (ISSN)

  • 0148-0227

Additional Document Info

start page

  • 24421

end page

  • 24447


  • 99


  • C12