Tropospheric delays

Within the weekly processing of the SIRGAS Continuously Operating Network (SIRGAS-CON), the SIRGAS Analysis Centres operationally estimate tropospheric Zenith Path Delays (ZPD) with an hourly sampling rate. These ZPD estimates are the input data for the generation of SIRGAS tropospheric products, which provide weekly combined troposphere estimates of high-reliability for each SIRGAS station. The station positions, as a necessary part of this analysis, are taken from the SIRGAS weekly combined solutions. Consequently, stations without estimated positions in the weekly combination are not included in the combined tropospheric solution.

The SIRGAS tropospheric products are computed by the SIRGAS Analysis Centre for the Neutral Atmosphere (CIMA), which is operated by the Facultad de Ingeniería of the Universidad Nacional de Cuyo (UNCuyo, Mendoza, Argentina) in cooperation with the Facultad de Ingeniería of the Universidad Juan Agustín Maza (Mendoza, Argentina) and with support of the Argentinean Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET).

The SIRGAS tropospheric products are weekly generated with a latency of 30 days. They are available with an hourly sampling rate in daily SINEX TRO files since January 2014 and they can be downloaded from

ftp://ftp.sirgas.org/pub/gps/SIRGAS-ZPD/

More details about the processing strategy can be found at

Mackern M.V., Mateo M.L., Camisay M.F., Morichetti P.V.: Tropospheric products from high-level GNSS processing in Latin America. In: 27th IUGG General Assembly. Montreal, Canada. July 8 - 18, 2019.

Whenever you use the SIRGAS tropospheric products, please include this publication as a citation.

 

SIRGAS ionospheric maps

The ionosphere over the Central and South American area presents a particularly complex behaviour because the free electron distribution is strongly affected by the Equatorial Anomaly and the distortion of the geomagnetic field (with respect to its dipolar approximation). The high-quality dual-frequency GNSS observations provided by the SIRGAS-CON network constitute an invaluable source of information for continuously monitoring this complex phenomenon. In order to exploit this opportunity, SIRGAS promoted the establishment of analysis centres devoted to that kind of studies. In this context, since July 2005 the Universidad Nacional de La Plata (Argentina), official SIRGAS Analysis Centre for the Ionophere, produces hourly maps of vertical total electron content (vTEC) for the SIRGAS region. These maps, called SIRGAS-UNLP ionospheric maps, are computed applying the La Plata Ionospheric Model (LPIM), which implements a thin-layer ionospheric approximation particularly tailored for the SIRGAS region. Twenty four maps per day, presented in graphical and numerical formats (grids of 1º×1º in latitude and longitude) and daily movies are available at

http://cplat.fcaglp.unlp.edu.ar/

The SIRGAS-UNLP maps of vTEC are being used for different kind of studies such as validate the International Reference Ionosphere (IRI) over the South American region, improving the performances of single-frequency GPS receivers, and the the feasibility of computing the ionospheric correction for a regional satellite based augmentation system (SBAS). This study was promoted by the Internation Civil Aviation Organization (ICAO) in the framework of its so-called “Solución de Aumentación para el Caribe, Centro y Sur América” (SACCSA) project.

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