Discussion on the approximations made in the practical implementation of the remove compute restore technique in regional geoid modelling
2005 (English)In: Journal of Geodesy, ISSN 0949-7714, E-ISSN 1432-1394, Vol. 78, no 11-12, 645-653 p.Article in journal (Refereed) Published
The remove-compute-restore (RCR) technique is the most well known method for regional gravimetric geoid determination today. Its basic theory is the first-order approximation of either Molodensky’s method for quasi-geoid determination or the classical geoid modelling by Helmert’s second method of condensing the topography onto the geoid. Although the basic approximate formulae do not meet today’s demands for a 1-cm geoid, it is sometimes assumed that the removal of the less precise long-wavelength terrestrial gravity anomaly field from Stokes’s integral by utilising a higher-order reference field represented by a more precise Earth gravity model (EGM) and the restoration of the EGM as a low-degree geoid contribution will produce a geoid model of the desired accuracy. Further improvement is achieved also by removing and restoring a residual topographic effect, which favourably smoothes the gravity anomaly to be integrated in Stokes’s formula. However, it is shown here that the RCR technique fails to tune down the long-wavelength gravity signal from the terrestrial data, and the EGM actually only reduces, in a non-optimised way, the truncation error committed by limiting the Stokes integration to a small region around the computation point. Hence, in order to take full advantage of a precise EGM, especially one from new dedicated satellite gravimetry, Stokes’s kernel must be modified in a suitable way to match the errors of terrestrial gravity, EGM and truncation. In addition, topographic, atmospheric and ellipsoidal effects must be carefully applied.
Place, publisher, year, edition, pages
2005. Vol. 78, no 11-12, 645-653 p.
Regional geoid modelling, Remove–compute–restore (RCR) technique
IdentifiersURN: urn:nbn:se:kth:diva-10815DOI: 10.1007/s00190-004-0430-1ISI: 000229856700001ScopusID: 2-s2.0-20444407955OAI: oai:DiVA.org:kth-10815DiVA: diva2:228017
QC 201008232009-07-222009-07-222010-08-23Bibliographically approved