Tropospheric wet delay estimation using GNSS: Case study of a permanent network in Egypt

Mousa, Ashraf; AbouAly, Nadia; Sharaf, Magdy; Zahra, Hesham Shaker; Darrag, Mohamed

doi:10.1016/j.nrjag.2016.01.002

Cited by 8 publications

(2 citation statements)

References 4 publications

(4 reference statements)

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“…Several novel concepts based on atmospheric parameters obtained from the numerical weather prediction (NWP) model have allowed for an improvement of the tropospheric effect and the ellipsoidal height can now be determined with enhanced accuracy of 1-2 cm [59]. It is also possible to estimate the troposphere via processing [60][61][62], with station-dependent factors, such as multipath and antenna phase centre issues being the remaining limiting factors in determining the ellipsoid height.…”

Section: Gnss and Its Accuracymentioning

confidence: 99%

Altitude on Cartographic Materials and Its Correction According to New Measurement Techniques

et al. 2021

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Determining the correct height of mountain peaks is vital for tourism, but it is also important as a reference point for devices equipped with GPS (Global Positioning System), e.g., watches or car navigation systems. The peak altitude data are part of geographic and geodetic information. As more modern technologies and equipment become available, their precisions should increase. However, verification of peak heights is usually only conducted for the highest, well-known mountains—lower peaks or mountain passes are rarely verified. Therefore, this study focuses on an investigation of 12 altitude points on a section of the longest and most famous touristic trail in Poland (the Main Beskid Trail), located in the Orava–Żywiec Beskids Mts (Mountains). The aim of this research is to measure and verify the heights of the 12 selected mountain peaks, in addition to evaluating the chosen methods based on the quality of the obtained data and determining their suitability and opportunities for use in further research. Measurements were obtained at the most specific height points—on the 12 highest points of the summits. This study compares two modern measurement techniques: the global navigation satellite system (GNSS) and light detection and ranging (LiDAR). The obtained results were later compared with those widely used on the internet and in printed materials (period covered: 1884–2015). This analysis demonstrates that lesser-known objects are rarely the subject of remeasurement and significant altitude errors may occur, primarily because the heights originated from a source in the past when modern methods were not available. Our findings indicate that the heights of the peaks presented in cartographic materials are inaccurate. The assumed heights should be corrected by direct measurements using modern techniques.

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Section: Gnss and Its Accuracymentioning

confidence: 99%

Altitude on Cartographic Materials and Its Correction According to New Measurement Techniques

et al. 2021

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“…It is mainly related to the water vapour and is difficult to be modelled with high accuracy, since water vapour is not a well-mixed constituent of the atmosphere (Resch, 1984). As a result, the estimation of the wet component of the ZTDs is important in high-precision GNSS applications (Mousa et al, 2016;Rothacher and Beutler, 1998).…”

Section: Introductionmentioning

confidence: 99%

MSE-impact of PPP-RTK ZTD estimation strategies

Wang

Khodabandeh

Teunissen

2018

Advances in Space Research

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In PPP-RTK network processing, the wet component of the zenith tropospheric delay (ZTD) cannot be precisely modelled and thus remains unknown in the observation equations. For small networks, the tropospheric mapping functions of different stations to a given satellite are almost equal to each other, thereby causing a near rank-deficiency between the ZTDs and satellite clocks. The stated near rank-deficiency can be solved by estimating the wet ZTD components relatively to that of the reference receiver, while the wet ZTD component of the reference receiver is constrained to zero. However, by increasing network scale and humidity around the reference receiver, enlarged mismodelled effects could bias the network and the user solutions. To consider both the influences of the noise and the biases, the mean-squared errors (MSEs) of different network and user parameters are studied analytically employing both the ZTD estimation strategies. We conclude that for a certain set of parameters, the difference in their MSE structures using both strategies is only driven by the square of the reference wet ZTD component and the formal variance of its solution. Depending on the network scale and the humidity condition around the reference receiver, the ZTD estimation strategy that delivers more accurate solutions might be different. Simulations are performed to illustrate the conclusions made by analytical studies. We find that estimating the ZTDs relatively in large networks and humid regions (for the reference receiver) could significantly degrade the network ambiguity success rates. Using ambiguity-fixed network-derived PPP-RTK corrections, for networks with an inter-station distance within 100 km, the choices of the ZTD estimation strategy is not crucial for single-epoch ambiguity-fixed user positioning. Using ambiguity-float network corrections, for networks with inter-station distances of 100, 300 and 500 km in humid regions (for the reference receiver), the root-mean-squared errors (RMSEs) of the estimated user coordinates using relative ZTD estimation could be higher than those under the absolute case with differences up to millimetres, centimetres and decimetres, respectively.

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Characteristic of Precipitable Water Vapor in 2017–2019 Over Bandung Estimated by GPS Data

Radiana

Hamdi

Aditiya³

et al. 2022

Springer Proceedings in Physics

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Tropospheric wet delay estimation using GNSS: Case study of a permanent network in Egypt

Cited by 8 publications

References 4 publications

Altitude on Cartographic Materials and Its Correction According to New Measurement Techniques

Altitude on Cartographic Materials and Its Correction According to New Measurement Techniques

MSE-impact of PPP-RTK ZTD estimation strategies

Characteristic of Precipitable Water Vapor in 2017–2019 Over Bandung Estimated by GPS Data

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