Considering different recent advancements in GNSS on real-time zenith troposphere estimates

Hadas, Tomasz ORCIDiD
Hobiger, Thomas
Hordyniec, Pawel

DOI: https://doi.org/10.1007/s10291-020-01014-w
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/10686
Hadas, Tomasz; Hobiger, Thomas; Hordyniec, Pawel, 2020: Considering different recent advancements in GNSS on real-time zenith troposphere estimates. In: GPS Solutions, 24, 4, DOI: https://doi.org/10.1007/s10291-020-01014-w. 
 
Hadas, Tomasz; Institute of Geodesy and Geoinformatics, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
Hobiger, Thomas; Institute of Navigation, University of Stuttgart, Stuttgart, Germany
Hordyniec, Pawel; SPACE Research Centre, RMIT University, Melbourne, Australia

Abstract

Global navigation satellite system (GNSS) remote sensing of the troposphere, called GNSS meteorology, is already a well-established tool in post-processing applications. Real-time GNSS meteorology has been possible since 2013, when the International GNSS Service (IGS) established its real-time service. The reported accuracy of the real-time zenith total delay (ZTD) has not improved significantly over time and usually remains at the level of 5–18 mm, depending on the station and test period studied. Millimeter-level improvements are noticed due to GPS ambiguity resolution, gradient estimation, or multi-GNSS processing. However, neither are these achievements combined in a single processing strategy, nor is the impact of other processing parameters on ZTD accuracy analyzed. Therefore, we discuss these shortcomings in detail and present a comprehensive analysis of the sensitivity of real-time ZTD on processing parameters. First, we identify a so-called common strategy, which combines processing parameters that are identified to be the most popular among published papers on the topic. We question the popular elevation-dependent weighting function and introduce an alternative one. We investigate the impact of selected processing parameters, i.e., PPP functional model, GNSS selection and combination, inter-system weighting, elevation-dependent weighting function, and gradient estimation. We define an advanced strategy dedicated to real-time GNSS meteorology, which is superior to the common one. The a posteriori error of estimated ZTD is reduced by 41%. The accuracy of ZTD estimates with the proposed strategy is improved by 17% with respect to the IGS final products and varies over stations from 5.4 to 10.1 mm. Finally, we confirm the latitude dependency of ZTD accuracy, but also detect its seasonality.