Combination of the Weekly Solutions Delivered by the SIRGAS Processing Centres for the SIRGAS-CON Reference Frame

Abstract

The SIRGAS reference frame is given by more than 200 continuously operating stations (SIRGAS-CON network), which are classified in four sub-networks: a continental one (SIRGAS-CON-C) with about 100 stations homogeneously distributed over Latin America and the Caribbean, and three densification sub-networks (SIRGAS-CON-D) covering the northern part, the middle part, and the southern part of the SIRGAS region. Each sub-network is processed by one of the SIRGAS Processing Centres: DGFI (Germany) is responsible for the SIRGAS-CON-C network, IGAC (Colombia) for the northern densification sub-network, IBGE (Brazil) for the middle one, and CIMA (Argentina) for the southern one. These Processing Centres deliver loosely constrained weekly solutions, which are integrated in a unified solution by the SIRGAS Combination Centres operating at DGFI and IBGE. The DGFI (i.e. IGS RNAAC SIR) weekly combinations are delivered to the IGS Data Centres for the global polyhedron, and are made available for users as official SIRGAS weekly reference frame solution. The IBGE weekly combinations provide control and redundancy. This paper describes the combination strategy applied by DGFI, emphasizing the evaluation of the individual solutions and the quality control of the final weekly combinations. The reliability of the resulting coordinates is estimated by comparing them with those produced by IBGE and the weekly combinations of the IGS global network.