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See detailFirst Zenith Total Delay and Integrated Water Vapour Estimates from the Near Real-Time GNSS Data Processing Systems at the University of Luxembourg
Ahmed, Furqan UL; Teferle, Felix Norman UL; Bingley, Richard

Poster (2012, April)

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See detailFirst Zenith Total Delay and Integrated Water Vapour Estimates from the Near Real-Time GNSS Data Processing Systems at the University of Luxembourg
Ahmed, Furqan UL; Teferle, Felix Norman UL; Bingley, Richard

Poster (2012, March 16)

Since June 2011, the University of Luxembourg has started in collaboration with the University of Nottingham a PhD project entitled “The Potential of Precipitable Water Vapour Measurements using Global ... [more ▼]

Since June 2011, the University of Luxembourg has started in collaboration with the University of Nottingham a PhD project entitled “The Potential of Precipitable Water Vapour Measurements using Global Navigation Satellite Systems in Luxembourg (PWVLUX)”, which is funded by the Fonds National de la Recherche (FNR) Luxembourg. The research objectives of the project are to study the potential for improvements in short-term weather forecasts and long-term climate variability for Luxembourg and the Greater Region by inclusion of the observations from Global Navigation Satellite Systems (GNSS) in the existing techniques. To achieve the research objectives, systems are being set up at the University of Luxembourg which process ground-based GNSS data for the provision of zenith total delay (ZTD) and integrated water vapour (IWV) estimates in real-time, near real-time and post-processing modes. Through collaboration with the Administration du cadastre et de la topographie (Luxembourg) and the Service public de Wallonie (Belgium), the coverage of the available GNSS permanent networks is improved over the primary project area, although also data from other European and global networks are processed. The meteorological analysis of the PWVLUX products is supported through collaborations with the Meteorological Service of the Administration de la navigation aérienne and the EUMETNET project E-GVAP. In this study we present the first ZTD and IWV estimates obtained from the near-real time processing systems in development at the University of Luxembourg. In a preliminary evaluation we compared their performance to some state-of-the-art systems already in operation and found that the ZTD estimates agree up to a few millimeters and the IWV estimates agree at the sub-millimeter level. [less ▲]

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See detailEvaluation of GNSS as a Tool for Monitoring Tropospheric Water Vapour
Ahmed, Furqan UL

Bachelor/master dissertation (2010)

Global Navigation Satellite Systems have the potential to become a significant tool in climate research ... [more ▼]

Global Navigation Satellite Systems have the potential to become a significant tool in climate research due to the fact that GNSS data can be processed in order to estimate the propagation delay experienced by the signal in atmosphere. If the ground pressure and temperature is known, the signal propagation path delay can be related to the amount of water vapour in the atmosphere. This thesis project focuses on the evaluation of GNSS as a tool for atmospheric water vapour estimation. In the first part of the project, various GNSS data processing software packages were compared by processing the same set of data and performing a statistical comparison of the estimates of zenith total delay obtained by each package. The software packages compared are GIPSY‐OASIS, Bernese GNSS Processing Software, GAMIT and magicGNSS. Also different strategies and methods, such as double‐differencing and precise point positioning,  are  investigated.  The  output from the  packages  is  validated  using  delay measurements obtained from ECMWF and RCA numerical models. It was observed that the output from climate models agrees with that from the software packages and the output from various software packages have a similarity between each other within 3 millimeters. In the second part of the project, simulations of new GNSS are carried out using in‐house software developed at Chalmers and SP Technical Research Institute of Sweden in order to investigate new methods and possible future improvements. The effect of local errors on atmospheric delay estimates from GPS, GLONASS and Galileo was studied through simulations. A hypothetical system formed by combination of the constellations of GPS, GLONASS and Galileo was also simulated and it was found to be least susceptible to local errors. Simulations were performed by varying some Keplerian orbital elements for Galileo system and it was observed that an orbit inclination between 60 degree and 65 degree would have been optimum for Galileo system. [less ▲]

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See detailAnalysis and Design of a Synthetic Aperture Radar System
Ahmed, Furqan UL

Bachelor/master dissertation (2008)

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