Representation of the Earth’s Gravity Field in the Southern part of the African Plate

A new digital gravity field model (SAGM2005) is presented, representing the free air anomaly and the height anomaly in the southern part of the African plate. A total of 12,203 gravity observations together with 5,486 free air GRACE-only data points were used in the process of Least-Squares Collocations (LSC) in order to carry the present representation out. A new computer algorithm was written, as a Matlab application, to calculate the observed covariance function as a primary step of the collocation procedure. The LSC method was applied as described by Moritz (1980) assuming a constant standard error of 3 mGal to the free air data points. The present work aimed to show the effect of introducing GRACE-only data with land observations on the precision of the calculated digital models, which represent the gravity field components in the studied area with spatial resolution of 0.1°, which is quite suitable to be used in regional studies.