Assessment of the Impact of GNSS Processing Strategies on the Long-Term Parameters of 20 Years IWV Time Series

Baldysz, Zofia; Nykiel, Grzegorz; Figurski, Mariusz; Araszkiewicz, Andrzej

doi:10.3390/rs10040496

Cited by 21 publications

(15 citation statements)

References 47 publications

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“…Different strategies exist to obtain ZTD estimations, e.g., the network approach based on double differences or the Precise Point Positioning (PPP) based on undifferenced observations. A comprehensive analysis using different mapping functions, cutoff angles, and positioning methods has been performed by Baldysz et al [11]. In that study, the PPP performed better than the differential approach for PWV linear trend analysis.…”

Section: Introductionmentioning

confidence: 99%

Potential of Cost-Efficient Single Frequency GNSS Receivers for Water Vapor Monitoring

et al. 2018

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Dual-frequency Global Navigation Satellite Systems (GNSSs) enable the estimation of Zenith Tropospheric Delay (ZTD) which can be converted to Precipitable Water Vapor (PWV). The density of existing GNSS monitoring networks is insufficient to capture small-scale water vapor variations that are especially important for extreme weather forecasting. A densification with geodetic-grade dual-frequency receivers is not economically feasible. Cost-efficient single-frequency receivers offer a possible alternative. This paper studies the feasibility of using low-cost receivers to increase the density of GNSS networks for retrieval of PWV. We processed one year of GNSS data from an IGS station and two co-located single-frequency stations. Additionally, in another experiment, the Radio Frequency (RF) signal from a geodetic-grade dual-frequency antenna was split to a geodetic receiver and two low-cost receivers. To process the single-frequency observations in Precise Point Positioning (PPP) mode, we apply the Satellite-specific Epoch-differenced Ionospheric Delay (SEID) model using two different reference network configurations of 50–80 km and 200–300 km mean station distances, respectively. Our research setup can distinguish between the antenna, ionospheric interpolation, and software-related impacts on the quality of PWV retrievals. The study shows that single-frequency GNSS receivers can achieve a quality similar to that of geodetic receivers in terms of RMSE for ZTD estimations. We demonstrate that modeling of the ionosphere and the antenna type are the main sources influencing the ZTD precision.

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Section: Introductionmentioning

confidence: 99%

Potential of Cost-Efficient Single Frequency GNSS Receivers for Water Vapor Monitoring

et al. 2018

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“…Therefore, we had to extract ZWD from Equation (1). To this end, we used the Saastamoinen hydrostatic model [9] and surface meteorological parameters derived from the ERA5 model [28] and interpolated at the locations of the stations [29]. As we focus on PWV differences, this approach was acceptable.…”

Section: Methodsmentioning

confidence: 99%

“…Tropospheric parameters were estimated using precise point positioning (PPP) method with global mapping function (GMF) [30]. Used data were described in detail in our previous study [29]. Hourly ZTD for each station was converted to the PWV according to the described methodology in Section 2.…”

Section: Impact Of the New Coefficients On The Pwv Estimated At Gnss mentioning

confidence: 99%

Improved Empirical Coefficients for Estimating Water Vapor Weighted Mean Temperature over Europe for GNSS Applications

Baldysz

Nykiel

2019

Remote Sensing

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Development of the so-called global navigation satellite system (GNSS) meteorology is based on the possibility of determining a precipitable water vapor (PWV) from a GNSS zenith wet delay (ZWD). Conversion of ZWD to the PWV requires application of water vapor weighted mean temperature (Tm) measurements, which can be done using a surface temperature (Ts) and its linear dependency to the Tm. In this study we analyzed up to 24 years (1994–2018) of data from 49 radio-sounding (RS) stations over Europe to determine reliable coefficients of the Tm-Ts relationship. Their accuracy was verified using 109 RS stations. The analysis showed that for most of the stations, there are visible differences between coefficients estimated for the time of day and night. Consequently, the ETm4 model containing coefficients determined four times a day is presented. For hours other than the primary synoptic hours, linear interpolation was used. However, since this approach was not enough in some cases, we applied the dependence of Tm-Ts coefficients on the time of day using a polynomial (ETmPoly model). This resulted in accuracy at the level of 2.8 ± 0.3 K. We also conducted an analysis of the impact of this model on the PWV GNSS. Analysis showed that differences in PWV reached 0.8 mm compared to other commonly used models.

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“…In geodetic applications the standard method is to estimate an equivalent zenith propagation delay together with a linear horizontal gradient. Early results showed an improved repeatability for the estimated coordinates when estimating gradients using GPS data (Bar-Sever et al, 1998;Meindl et al, 2004). A recent study (Zhou et al, 2017) found that estimating gradients with a temporal resolution of 1 h can achieve even better positioning performance than strategies where gradients are estimated with resolutions of many hours up to 1 d.…”

Section: Introductionmentioning

confidence: 99%

High-temporal-resolution wet delay gradients estimated from multi-GNSS and microwave radiometer observations

Ning

Elgered

2021

Atmos. Meas. Tech.

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Abstract. We have used 1 year of multi-GNSS observations at the Onsala Space Observatory on the Swedish west coast to estimate the linear horizontal gradients in the wet propagation delay. The estimated gradients are compared to the corresponding ones from a microwave radiometer. We have investigated different temporal resolutions from 5 min to 1 d. Relative to the GPS-only solution and using an elevation cutoff angle of 10∘ and a temporal resolution of 5 min, the improvement obtained for the solution using GPS, Glonass, and Galileo data is an increase in the correlation coefficient of 11 % for the east gradient and 20 % for the north gradient. Out of all the different GNSS solutions, the highest correlation is obtained for the east gradients and a resolution of 2 h, while the best agreement for the north gradients is obtained for 6 h. The choice of temporal resolution is a compromise between getting a high correlation and the possibility of detecting rapid changes in the gradient. Due to the differences in geometry of the observations, gradients which happen suddenly are either not captured at all or captured but with much less amplitude by the GNSS data. When a weak constraint is applied in the estimation of process, the GNSS data have an improved ability to track large gradients, however, at the cost of increased formal errors.

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Assessment of the Impact of GNSS Processing Strategies on the Long-Term Parameters of 20 Years IWV Time Series

Cited by 21 publications

References 47 publications

Potential of Cost-Efficient Single Frequency GNSS Receivers for Water Vapor Monitoring

Potential of Cost-Efficient Single Frequency GNSS Receivers for Water Vapor Monitoring

Improved Empirical Coefficients for Estimating Water Vapor Weighted Mean Temperature over Europe for GNSS Applications

High-temporal-resolution wet delay gradients estimated from multi-GNSS and microwave radiometer observations

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