SIRGAS: the geodetic reference frame in Latin America and the Caribbean.

C. BRUNINI; L. SÁNCHEZ; V. MACKERN; L. MATEO; W. MARTÍNEZ; R. LUZ

Marne la Vallee, France

Simposio; IAG Commission 1 Symposium 2010 Reference Frames for Applications in Geosciences; 2010

IAG Commission 1

SIRGAS (Sistema de Referencia Geocéntrico para las Américas) deals with the definition, realization, and maintenance of the 3D geocentric reference system for Latin America and the Caribbean, including a gravity field-related vertical reference system. The SIRGAS activities are coordinated by three working groups: The SIRGAS-WGI (Reference System) is committed to establish and maintain a continental-wide geocentric reference frame as a regional densification of the ITRF. This objective was initially accomplished through two continental GPS campaigns in 1995 and 2000, comprising 58 and 184 stations, respectively. Today, it is realized the SIRGAS Continuously Operating Network (SIRGAS-CON), which includes about 230 permanent GNSS sites. The SIRGAS-CON network is weekly processed by the SIRGAS Analysis Centres providing weekly station positions aligned to the ITRF as well as loosely constrained weekly solutions for further combinations of the network such as the integration in the IGS polyhedron or the computation of multi-year solutions. The SIRGAS-WGII (Geocentric Datum) supports the adoption of SIRGAS in the Latin American and Caribbean countries by means of national densifications of the continental network. This also includes the development of adequate tools to modernize the geo-data referring to the old horizontal datums and to promote the use of SIRGAS as reference frame in practical and scientific applications at national level. The SIRGAS-WGIII (Vertical Datum) is dedicated to the definition and realization of a unified vertical reference system within a global frame. Its central purpose is to refer the geopotential numbers (or physical heights) in all countries to one and the same equipotential surface, which has to be defined globally. This also considers the transformation of the existing height datums into the new system. In addition to the issues covered by the three Working Groups, based on the observational infrastructure provided by the SIRGAS-CON network, initiatives related to the atmospheric modelling and the implementation of real time applications have been strongly developed in the last three years. According to this, the present contribution describes the main achievements and new challenges taken under consideration by SIRGAS to continue providing a long-term stable and high-precise reference frame for Latin America and the Caribbean.