Accuracy Assessment of Gravity Field Models by Independent Satellite Crossover Altimetry

Abstract. Continual progress in Earth gravity field modelling requires ever more precise data sets for their accuracy assessment as well as refinements in the assessment procedures. The method used here is based on Latitude Lumped Coefficients and makes use of single-satellite crossover altimetry data (independent of the tested model). The method effectively rationa-lizes the residuals in LLC measurements with the model’s covariance matrix. It has been developed in years 1992 – 2000 and applied various gravity field models, from GEM T2 to the GRIM5’s. We now apply it to EIGEN-1S & 2 which include highly precise continuous tracking data from the CHAMP mission. For the first time these CHAMP models recommend degree-dependent calibration fa-ctors for its covariance matrix. We find these factors are needed to explain the independent LLC measurements on the ERS and GEOSAT orbits