Workshop 2018
Laura Sanchez - SIRGAS: 25 years providing the geodetic infrastructure in Latin America - October 29, 2018 • 697 Views
SIRGAS was created in 1993 during the International Conference for the Definition of a South American Geocentric Reference System held in Asuncion, Paraguay. This conference was promoted and supported by the International Association of Geodesy (IAG), the Pan-American Institute for Geography and History (PAIGH), and the US Defence Mapping Agency (DMA), today National Geospatial-Intelligence Agency (NGA). The first realization of SIRGAS (SIRGAS95) is a high-precision GPS network of 58 points distributed over South America and refers to ITRF94, epoch 1995.4. In 2000, this network was re-measured and extended to the Caribbean, Central and North American countries. To account for this extension, the meaning of the acronym changed from the original “Sistema de Referencia Geocéntrico para América del Sur”, to the current “Sistema de Referencia Geocéntrico para las Américas”. This second realization (SIRGAS2000) includes 184 GPS stations and refers to ITRF2000, epoch 2000.4. The present realization of SIRGAS is given by a network of continuously operating GNSS stations distributed over Latin America called SIRGAS-CON (SIRGAS Continuously Operating Network). SIRGAS-CON is processed on a weekly basis by ten analysis centres to generate instantaneous weekly station positions aligned to the ITRF and multi-year (cumulative) reference frame solutions. The instantaneous weekly positions are especially useful when strong earthquakes cause co-seismic displacements or strong relaxation motions at the SIRGAS stations disabling the use of previous coordinates. The multi-year solutions provide the most accurate and up-to-date SIRGAS station positions and velocities. They are used for the realization and maintenance of the SIRGAS reference frame between two releases of the ITRF. Today, SIRGAS is the backbone for all regional projects based on the generation, use, and analysis of geo-referenced data at national as well as at international level. Besides providing the reference for a wide range of scientific applications such as the monitoring of Earth crust deformations, vertical movements, sea level variations, atmospheric studies, etc., SIRGAS is also the platform for practical applications such as engineering projects, digital administration of geographical data, geospatial data infrastructures, etc. In this presentation, we provide a summary of the milestones in the establishment and maintenance of SIRGAS as the geodetic infrastructure in Latin America during the last 25 years. We emphasize the main challenges faced currently by SIRGAS: (1) A high-resolution monitoring of the reference frame deformation by means of more reference stations and improved analysis standards; (2) Co-seismic deformation models for the transformation of station positions between pre- and post-seismic frame realisations; (3) Reliable modelling of non-lineal station movements in the reference frame computation to improve the estimation of epoch coordinates.

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