Analysis of a precise regional geoid model in Buenos Aires province computed by least squares collocation

D. BAGÚ; D. DEL COGLIANO; M. SCHEINERT; R. DIETRICH; J. SCHWABE; L. MENDOZA

Mar del Plata

Congreso; International Geological and Geophysical Congress on the Southern Hemisphere; 2010

Instituto Nazionale di Oceanografia e di Geofisica Sperimentale, OGS, Trieste, Italy; Instututo de Geofísica "Daniel A. Valencio", Universidad de Buenos Aires, Argentina; Dipartimento di Scienze Geologiche, Universita di Urbino, Italy

An analysis of a precise regional geoid model in Buenos Aires province computed by Least Squares Collocation (LSC) is shown. The study zone (lat 35°S to 38.5°S, long 63°W to 58.5°W) is mainly flat with two zones at the south with rough topography.To achieve the goal, terrestrial and satellite data were combined in the well known Remove-Compute-Restore technique. The terrestrial data consisted in gravity observations, levelling heights and GPS on benchmarks. The long-wavelengths components of the Earth´s gravity field were modelled bythe EGM2008 global gravity model. The SRTM3v.4 was used to compute thetopographic effects in the Helmert´s second method of condensation scheme (short-wavelengths). Taking into account this reduction, gravity anomalies were computed.After removing the long and short wavelengths from the gravity anomalies, theresidual data (over 9462 gravity stations) was used to compute 156 residual geoid heights by LSC (Nlsc) using the GravSoft package. The differences with respect to the GPS/levelling heights observations (Nobs) were estimated (“only gravity solution”). The results show that 47% of the absolute differences between N lsc and Nobs are below 5cm, and 83% below 10cm.Other solutions using the 9462 residual gravity anomalies but now alsoGPS/levelling as input observations were computed, showing improvements with respect to the “only gravity solution”.