The energy conservation method is based on knowledge of the state vector and measurements of nonconservative forces. This is or will be provided by CHAMP, GRACE and GOCE. Here the analysis of one month of CHAMP state vector and accelerometer data is described. The energy conservation method is used to estimate the gravity potential at satellite altitude. When doing so we consider the tidal pote...

To select the best geo-potential model for the determination of Hong Kong and Shenzhen local geoids, three models EGM96, WDM94 and GPM98CR were tested in the region using GPS/leveling data and gravity measurements. The data include GPS/leveling observations at 43 stations, 640 gravity measurements covering the whole territory of Hong Kong, and 62 high precision GPS/leveling observations and 487...

In the last ten years significant advances have been made in gravity field modelling, culminating in general-purpose models like JGM-3, TEG-3 and EGM96. Significant defects remain in the quality of the models when applied to orbit determination of some altimeter satellites, leading to large orbit errors, characterised by the geographically-correlated nature of the altimeter crossover height dif...

In the original LARES mission the general relativistic Lense–Thirring effect would be detected by using as observable the sum of the residuals of the nodes of the existing passive geodetic laser-ranged LAGEOS satellite and of its proposed twin LARES. The proposed nominal orbital configuration of the latter one would reduce the systematic error due to the mismodelling in the even zonal harmonics...

The Lense-Thirring effect is currently being measured by means of a combination of the orbital residuals of the nodes of LAGEOS and LAGEOS II and the perigee of LAGEOS II. The claimed total error should be of the order of 20%. The most insidious systematic error is due to the mismodelled even zonal harmonics of the geopotential and amounts to 12.9%, according to the full covariance matrix of th...

Egypt has recentely established a new precise geodetic framework based on the global WGS84 datum to furnish a national GPS-based reference system. For agricultural development along the Nile valley, the National Agricultural Cadastral Network (NACN) has been established with a precision of 1 part per million. However, the orthometric heights of the 112-station network have been computed utilizi...