COSMIC: Geodetic applications in improving earth's gravity model

The routine GPS tracking data that will be collected for the precise orbit determination of the eight COSMIC spacecraft will contain valuable informat ion about the terrestrial gravity field. Numerical simulations based on cur rent straw-man mission scenarios have shown: (1) For the static model of th e gravity field, significant improvement is possible over our present knowl edge embodied in the EGM96 model, out to harmonic degree as high as 40. (2) With respect to time-varying gravitational signals, large-scale mass trans port processes in the geophysical fluids (e.g., atmosphere and oceans) can be detected or monitored during the mission, providing important global cha nge information. Further sophisticated simulations incorporating more reali stic force models will be needed once COSMIC mission scenario and spacecraf t design are completely defined.