Processing of the SIRGAS 2000 GPS Network at DGFI

After the first SIRGAS campaign carried out in 1995, a second GPS campaign was performed during a ten days period in May 2000. This time the project did not only include the South American countries but also Central and North America as well as the Caribbean. DGFI has processed the entire network comprising a total of 184 sites. This paper presents the results of some specific analyses regarding a number of error sources and processing strategy alternatives. Among the error influences are the site displacements due to ocean tide and atmospheric pressure loading, and the troposphere modeling. Regarding the processing aspects, the setting of the adjustment elevation angle cutoff, the ambiguity fixing, and the elevation dependent weighting of the observations are discussed. The strategy considered optimal in particular for improving the accuracy of the height estimates was applied to the network processing. The performance achieved is demonstrated mainly by daily repeatabilities of single baselines of various lengths as well as of subnetworks.