An Earth gravity field model complete to degree and order 150 from GRACE: EIGEN-GRACE02S

A new medium-wavelength gravity field model has been calculated from 110 days of GRACE tracking data, called EIGEN-GRACE02S. The solution has been derived solely from satellite orbit perturbations and is independent from oceanic and continental surface gravity data. This model that resolves the geoid with an accuracy of better than 1 mm at a resolution of 1000 km half-wavelength is about one order of magnitude more accurate than recent CHAMP-derived global gravity models and over two orders of magnitude more accurate than the latest pre-CHAMP satellite-only gravity models. This progress in accuracy together with an increase in resolution are the result of the dedicated instrumentation of the twin GRACE satellites. The instrumentation allows for continuous GPS-GRACE high-low satellite-to-satellite tracking, on-board measurement of non-gravitational accelerations, precise attitude determination, and-being the most important component-the observation of the intersatellite distance and its rate of change.