Maria Virginia Mackern

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Comparison of Different Techniques for Tropospheric Wet Delay Retrieval Over South America and Surrounding Oceans

International Association of Geodesy symposia, 2015

Water vapour (WV) plays a fundamental role in several weather processes that deeply influence hum... more Water vapour (WV) plays a fundamental role in several weather processes that deeply influence human activities. Satellite based radiometers, Ground based Global Navigation Satellite Systems (GNSS) and Numerical Weather Models (NWM) permit to obtain either measurements or estimates or forecasts of WV. This work presents a 2 years systematic comparison to address the agreement on the tropospheric wet delay retrieved by the three mentioned independent techniques over permanent stations belonging to SIRGAS (Sistema de Referencia para las Americas) GNSS network. SIRGAS tropospheric total delay estimations are compared with the official International GNSS Service (IGS) ones, with the measurements from the Jason-1 satellite radiometer (JMR) in terms of Zenith Wet Delays (ZWD) and, finally, with the ZWD computed from ERA Interim, the last reanalysis dataset from the European Center for Medium-Range Weather Forecasts (ECMWF). All the differences between the techniques, which were considered in order to yield a reliable comparison, are discussed. The statistical results of mean (μ), standard deviation (σ) and correlation (ρ), show that the highest agreement is reached between SIRGAS and IGS products (μ = −0. 5 mm, \(\sigma = 5.6\,\mathrm{mm}\), ρ = 0. 98), whereas slightly worse values are obtained in the comparisons with the JMR measurements (\(\mu = -7.4\,\mathrm{mm}\), \(\sigma = 15.4\,\mathrm{mm}\), ρ = 0. 91), and the ERA Interim data (μ = −1. 5 mm, σ = 16. 6 mm, ρ = 0. 91).

A Terrestrial Reference Frame (TRF), coordinates and velocities for South American stations: contributions to Central Andes geodynamics

Advances in Geosciences, Dec 17, 2009

Satellite positioning systems allow the fixing of the location of a point on the Earth's surface ... more Satellite positioning systems allow the fixing of the location of a point on the Earth's surface with very good precision and accuracy. To do this, however, it is necessary to determine the point coordinates taking account the reference system and the movements that affect them because of tectonic plate movements. These reference systems are materialized by a significant number of continuous measurement stations in South America. In SIRGAS (Sistema de Referencia Geocéntrico para las Américas), there are four Analysis Centers that process the data collected from satellites of the Global Navigation Satellite Systems (GNSS), with the primary purpose to maintain the international terrestrial reference frame through calculation of the coordinates and velocities of the continuous GNSS stations of the SIRGAS-CON Network. In this work, we demonstrate the quality of the solutions from CIMA, one of the SIRGAS official processing centers operating in Mendoza, Argentina, in comparison with other South American processing centers. The importance of precise calculations of coordinates and velocities in a global frame is also shown. Finally, we give estimations of velocities from stations located within deformation zones in the Central Andes.

Maria Virginia Mackern

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