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Regional Models

Africa (AGP2007)

  Author: C.L. Merry     Created: 2007    Resp: C.L. Merry  
      Status: PUBLIC    

This geoid is an update on an earlier model (AGP2007) of the geoid for Africa, and incorporates new contributions from the KMS02 marine gravity dataset, the SRTM30DEM and long wavelength harmonic coefficients from the Eigen-GRACE GL04C model. A uniform 5' grid of gravity anomalies derived from terrestrial gravity data has been combined with the marine data, and the combined dataset has been used with the geopotential model in a remove restore process. Two dimensional convolution has been used to computer residual height anomalies from residual gravity anomalies, including the contribution of the Molodensky G1 term. The geopotential model contribution has been restored and the height anomalies converted to geoidal heights. The final result is a 5' grid of geoidal heights covering the land mass of Africa.
There are significant gaps in the available terrestrial gravity data. These gaps mean that the accuracy of the final geoid model will be variable and generally less than desirable. Nevertheless good agreement is achieved with GPS/levelling results in western South Africa and northern Algeria.

C.L. Merry (2007). An updated geoid model for Africa. Presented at Symposium G2, XXIV General Assembly of the IUGG, Perugia, Italy, July 2007.