Validity and behaviour of tropospheric gradients estimated by GPS in Corsica

Morel, Laurent; Pottiaux, Eric; Durand, Frédéric; Fund, F.; Boniface, K.; Oliveira, Paulo Sergio de; Baelen, Joël Van

doi:10.1016/j.asr.2014.10.004

Cited by 25 publications

(21 citation statements)

References 26 publications

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“…Moreover, the correlation coefficient between ZTD time series derived from these two methods for all GPS stations are higher than 0.97. This finding corresponds to the results obtained from the previous studies [e.g., Ning et al, 2012;choy et al, 2013;Morel et al, 2014]. There is no noticeable relation between the size of mean bias and the standard deviation of two methods with the height of the GPS stations.…”

Section: Comparison Of Different Gps Processing With Radiosondesupporting

confidence: 91%

Estimation of GPS Tropospheric delays using different data processing strategies in Iran

Khaniani

Ghahremani²

2018

Annals of Geophysics

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In this study, the performance of different processing software and strategies on the estimation of Zenith Wet Delay (ZWD) from Iran Permanent GPS Network (IPGN) was evaluated. For this purpose, GAMIT (version 10.4) and Bernese (version 5.0) software were used to estimate the ZWD values in baseline and Precise Point Positioning (PPP) mode, respectively. Then, the GPS ZWD time series in Tehran, which is the only International GNSS Service (IGS) station in Iran, were validated with the corresponding values derived from the measurements of the nearby radiosonde site at Mehrabad airport. Based on one year of estimates in both network (or baseline) and PPP mode, the GPS and radiosonde ZWD were consistent with a mean bias of 6 mm and standard deviation of 12 mm. furthermore, the IGS final tropospheric products over 2011 were used to validate our GPS data processing in this study. The Results showed that there is a good agreement between our estimates and those obtained from IGS with a mean bias of less than 1 mm. Comparing PPP with the network GPS ZWD solutions in 15 stations of IPGN over one year, showed that two methods are consistent with mean bias and standard deviation of less than 2 and 5 mm. Finally, to examine the operational usage of IPGN tropospheric products, using the IGS ultra-rapid orbits the near real time ZTD were estimated and compared with final post processed solutions. For all stations, the near real time ZTD estimation results were comparable with the corresponding post processed estimates in terms of bias and standard deviation. The obtained correlation coefficient between final and near real time solutions was more than 0.95. These results suggest that ZTD derived from Iranian regional GPS network has the potential to incorporate in different meteorological applications.

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Section: Comparison Of Different Gps Processing With Radiosondesupporting

confidence: 91%

Estimation of GPS Tropospheric delays using different data processing strategies in Iran

Khaniani

Ghahremani²

2018

Annals of Geophysics

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“…Five of the solutions used GPS and GLONASS observations and six solutions used GPS-only observations; five of them are based on DD observations and six of them are computed using zero-difference data in PPP analysis. More information about TUW solutions can be found in Möller et al (2016), about GFZ in Bender et al (2009 and Deng et al (2011) and about CNAM in Morel et al (2014). For ROB, TUO and WUE solutions we refer the reader to Dach et al (2015).…”

Section: Std Retrievals From Gnss Observationsmentioning

confidence: 99%

Inter-technique validation of tropospheric slant total delays

et al. 2017

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Abstract. An extensive validation of line-of-sight tropospheric slant total delays (STD) from Global Navigation Satellite Systems (GNSS), ray tracing in numerical weather prediction model (NWM) fields and microwave water vapour radiometer (WVR) is presented. Ten GNSS reference stations, including collocated sites, and almost 2 months of data from 2013, including severe weather events were used for comparison. Seven institutions delivered their STDs based on GNSS observations processed using 5 software programs and 11 strategies enabling to compare rather different solutions and to assess the impact of several aspects of the processing strategy. STDs from NWM ray tracing came from three institutions using three different NWMs and ray-tracing software. Inter-techniques evaluations demonstrated a good mutual agreement of various GNSS STD solutions compared to NWM and WVR STDs. The mean bias among GNSS solutions not considering post-fit residuals in STDs was −0.6 mm for STDs scaled in the zenith direction and the mean standard deviation was 3.7 mm. Standard deviations of comparisons between GNSS and NWM ray-tracing solutions were typically 10 mm ± 2 mm (scaled in the zenith direction), depending on the NWM model and the GNSS station. Comparing GNSS versus WVR STDs reached standard deviations of 12 mm ± 2 mm also scaled in the zenith direction. Impacts of raw GNSS post-fit residuals and cleaned residuals on optimal reconstructing of GNSS STDs were evaluated at intertechnique comparison and for GNSS at collocated sites. The use of raw post-fit residuals is not generally recommended as they might contain strong systematic effects, as demonstrated in the case of station LDB0. Simplified STDs reconstructed only from estimated GNSS tropospheric parameters, i.e. without applying post-fit residuals, performed the best in all the comparisons; however, it obviously missed part of tropospheric signals due to non-linear temporal and spatial variations in the troposphere. Although the post-fit residuals cleaned of visible systematic errors generally showed a slightly worse performance, they contained significant tropospheric signal on top of the simplified model. They are thus recommended for the reconstruction of STDs, particularly during high variability in the troposphere. Cleaned residuals also showed a stable performance during ordinary days while containing promising information about the troposphere at low-elevation angles.

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“…Regardless, mean gradients should be close to zero, whereas dry gradients may tend to point slightly more to the equator, corresponding to latitudinal changes in atmosphere thickness (Meindl et al, 2004). Similarly, orography-triggered horizontal gradients can appear due to the presence of high mountain ranges in the vicinity of the station (Morel et al, 2015). Such systematic effects can reach the maximum submillimetre level, while a higher long-term gradient (i.e.…”

Section: Quality Of the Observations And Impact On Tropospheric Gradimentioning

confidence: 99%

Tropospheric products of the second GOP European GNSS reprocessing (1996–2014)

2017

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Abstract. In this paper, we present results of the second reprocessing of all data from 1996 to 2014 from all stations in International Association of Geodesy (IAG) Reference Frame Sub-Commission for Europe (EUREF) Permanent Network (EPN) as performed at the Geodetic Observatory Pecný (GOP). While the original goal of this research was to ultimately contribute to the realization of a new European Terrestrial Reference System (ETRS), we also aim to provide a new set of GNSS (Global Navigation Satellite System) tropospheric parameter time series with possible applications to climate research. To achieve these goals, we improved a strategy to guarantee the continuity of these tropospheric parameters and we prepared several variants of troposphere modelling. We then assessed all solutions in terms of the repeatability of coordinates as an internal evaluation of applied models and strategies and in terms of zenith tropospheric delays (ZTDs) and horizontal gradients with those of the ERA-Interim numerical weather model (NWM) reanalysis. When compared to the GOP Repro1 (first EUREF reprocessing) solution, the results of the GOP Repro2 (second EU-REF reprocessing) yielded improvements of approximately 50 and 25 % in the repeatability of the horizontal and vertical components, respectively, and of approximately 9 % in tropospheric parameters. Vertical repeatability was reduced from 4.14 to 3.73 mm when using the VMF1 mapping function, a priori ZHD (zenith hydrostatic delay), and non-tidal atmospheric loading corrections from actual weather data. Raising the elevation cut-off angle from 3 to 7 • and then to 10 • increased RMS from coordinates' repeatability, which was then confirmed by independently comparing GNSS tropospheric parameters with the NWM reanalysis. The assessment of tropospheric horizontal gradients with respect to the ERA-Interim revealed a strong sensitivity of estimated gradients to the quality of GNSS antenna tracking performance. This impact was demonstrated at the Mallorca station, where gradients systematically grew up to 5 mm during the period between 2003 and 2008, before this behaviour disappeared when the antenna at the station was changed. The impact of processing variants on long-term ZTD trend estimates was assessed at 172 EUREF stations with time series longer than 10 years. The most significant site-specific impact was due to the non-tidal atmospheric loading followed by the impact of changing the elevation cut-off angle from 3 to 10 • . The other processing strategy had a very small or negligible impact on estimated trends.

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Validity and behaviour of tropospheric gradients estimated by GPS in Corsica

Cited by 25 publications

References 26 publications

Estimation of GPS Tropospheric delays using different data processing strategies in Iran

Estimation of GPS Tropospheric delays using different data processing strategies in Iran

Inter-technique validation of tropospheric slant total delays

Tropospheric products of the second GOP European GNSS reprocessing (1996–2014)

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