An operational GNSS processing system for near-real-time tropospheric ZTD and IWV monitoring in South America: breaking the 2-hour lateness barrier!

J. M. ARAGÓN PAZ; L. MENDOZA; L. FERNÁNDEZ

Beijing

Congreso; Scientific Assembly of the International Association of Geodesy; 2021

International Association of Geodesy

The observation of atmospheric Water Vapor (WV) is fundamental in the study of the evolution of meteorological weather, especially in severe phenomena. Until recently, there was no operational systems in South America that could offer continuous WV observations, with sufficientlylow latencies, and significant density and geographic coverage, to allow their implementation in nowcasting meteorological models. On the other hand, Global Navigation Satellite Systems (GNSS) have shown to have the capacity to fill this gap in the study of atmospheric WV. In this workwe present such an operational system for South America. The unattended system process GNSS data streams and produces Integrated Water Vapor (IWV) observations for more than 40 sites in this region, in near-real-time (i.e., a timelines lower than 2-hours is achieved). In practice, the system produces estimates of the tropospheric Total Zenith Delay (ZTD), for sites in Argentina, Uruguay and southern Brazil, from the analysis of the GNSS observations provided by the regional Cartographic Agencies. The IWV observations are then obtained by incorporating surface meteorological data, also distributed in near-real-time by the regional Weather Services. All the products obtained duringthe processing are immediately and openly accessible by the whole community. The products have been compared with a posteriori results from several international GNSS Analysis Centers, at several common sites, and also with regional observations by independent techniques(e.g., radiosounding), to reliable quantify their quality and usefulness. The evaluation highlights their advantages in terms of temporal sampling and spatial resolution, with uncertainties falling within standard thresholds. Thus, the operational system provides IWV observations with adequate quality, and sufficient low latency, to be implemented in assimilation models for short-term forecasting, which are under development at several regional Weather Services.