A STUDY OF THE CHILEAN VERTICAL NETWORK THROUGH GLOBAL GEOPOTENTIAL MODELS AND THE CNES CLS 2011 GLOBAL MEAN SEA SURFACE

Abstract

Most aspects related to the horizontal component of the Geocentric Reference
System for the Americas (SIRGAS) have been solved. However, in the case of the
vertical component there are still aspects of definition, national realizations and
continental unification still not accomplished. Chile is no exception; due to its
particular geographic characteristics, a number of tide gauges (TG) had to be
installed in the coast from which the leveling lines that compose the Chilean
Vertical Network (CHVN) were established. This study explored the offsets of the
CHVN by two different approaches; one geodetic and one oceanographic. In the
first approach, the offsets were obtained in relation to the following Global
Geopotential Models (GGM): the satellite-only model (unbiased) GO_CONS_gcf_2_tim_r3 derived from GOCE satellite mission; EGM2008 (combined-biased); and GOEGM08, combining information from the GO_CONS_gcf_2_tim_r3 in long wavelengths (n max ~200) with the mean/short wavelengths of EGM2008 (n>200). In the oceanographic method, we used the CNES CLS 2011 Global Mean Sea surface and EIGEN_GRACE_5C GGM to obtain the values of MDT at the different TG. We also evaluated the CHVN in relation to different GGMs. The results showed consistency between the values obtained by the two methods at the TG of Valparaíso and Puerto Chacabuco. In terms of the evaluation of the GGM, GOEGM08 produced the best results.