SIRGAS: ITRF densification in Latin America and the Caribbean

L.SANCHEZ; BRUNINI C.; S. COSTA; M. V. MACKERN; W. MARTINEZ; W. SEEMULLER; A. DA SILVA

Vienna

Congreso; EGU 2009. European Geosciences Union General Assembly 2009; 2009

European Geosciences Union

The continental reference frame of SIRGAS (Sistema de Referencia Geocéntrico para las Américas) is realized by the SIRGAS Continuously Operating Network (SIRGAS-CON) composed by about 200 stations distributed over all Latin America and the Caribbean. SIRGAS member countries are qualifying their national reference frames by installing continuously operating GNSS stations, which have to be consistently integrated into the continental network. As the number of these stations is rapidly increasing, the analysis strategy of the SIRGAS-CON network is based on two hierarchy levels, namely: one core (SIRGAS-CON-C) network and several densification (SIRGAS-CON-D) sub-networks. The SIRGAS-CON-C network provides homogeneous continental coverage and stabile site locations, ensuring the long-term stability of the reference frame and the primary link to the ITRS. This network is processed by DGFI (Germany) as the IGS RNAAC-SIR. The SIRGAS-CON-D sub-networks improve the accessibility to the reference frame in the individual countries. These sub-networks shall correspond to the national reference frames, i.e., as an optimum there shall be as many sub-networks as countries in the region. Since at present not all of the countries are operating a processing centre, the existing stations are classified in three densification networks (a southern, a middle, and a northern one), which are processed by the SIRGAS Local Processing Centres CIMA (Argentina), IBGE (Brazil), and IGAC (Colombia) until new ones are installed. These four Processing Centres deliver loosely constrained weekly solutions for station coordinates, which are integrated in a unified solution by the SIRGAS Combination Centres (DGFI and IBGE). The main SIRGAS products are: loosely constrained weekly station coordinates in the SINEX format for the IGS polyhedron solutions; constrained weekly coordinates for practical applications in Latin America; and multi-annual (cumulative) solutions (coordinates + velocities) for practical and scientific applications requiring time depending positioning.