S. M. Klosko

TL;DR: The Earth Gravitational Model 1996 (EGM96) as discussed by the authors was developed by the NASA Goddard Space Flight Center (GSFC), the National Imagery and Mapping Agency (NIMA), and The Ohio State University (OSU) to develop an improved spherical harmonic model of the Earth's gravitational potential.

TL;DR: An improved Earth geopotential model, complete to spherical harmonic degree and order 70, has been determined by combining the Joint Gravity Model 1 (JGM 1) coefficients, and their associated error covariance, with new information from SLR, DORIS, and GPS tracking of TOPEX/Poseidon, laser tracking of LAGEOS 1, LS1, LS2, and Stella as discussed by the authors.

TL;DR: The TOPEX/POSEIDON mission objective requires that the radial position of the spacecraft be determined with an accuracy better than 13 cm RMS (root mean square). This stringent requirement is an order of magnitude below the accuracy achieved for any altimeter mission prior to the definition of the TOPEX mission as mentioned in this paper.

TL;DR: GEM-T2 as discussed by the authors is the latest in a series of Goddard Earth models of the terrestrial gravity field, which includes more than 6OU coefficients above degree 36, the limit for GEM-t1, and provides a dynamically determined model of the major tidal components which contains 90 terms.

TL;DR: The GEM-T1 model provides a simultaneous solution for a gravity model in spherical harmonics complete to degree and order 36, a subset of 66 ocean tidal coefficients for the long-wavelength components of 12 major tides, and 5-day averaged earth rotation and polar motion parameters for the 1980 period on as mentioned in this paper.