Impact of GPS antenna phase center models on zenith wet delay and tropospheric gradients

Ejigu, Yohannes Getachew; Hunegnaw, Addisu; Abraha, Kibrom Ebuy; Teferle, Felix Norman

doi:10.1007/s10291-018-0796-9

Cited by 12 publications

(10 citation statements)

References 22 publications

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“…Interestingly, the effects of the receivers PCO and PCV calibration are not obvious in the comparison of the results from processing strategies "GAL-IF0" and "GAL-IF1", which slightly differ with the results of Reference [34], are based on the double-difference processing that a 1.8 mm difference in the mean biases of ZWD is observed for different receiver antenna phase center correction models. This is mainly due to the ambiguities being resolved as the float in the PPP filter and thus the elevation-dependent receiver PCO variations are absorbed by the ambiguities.…”

Section: Station Namementioning

confidence: 56%

Performance Evaluation of Troposphere Estimated from Galileo-Only Multi-Frequency Observations

2020

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The tropospheric delays estimated from the Global Navigation Satellite System (GNSS) have been proven to be an efficient product for monitoring variations of water vapor, which plays an important role in meteorology applications. The operational GNSS water vapor monitoring system is currently based on the Global Positioning System (GPS) and GLObal NAvigation Satellite System(GLONASS) dual-frequency observations. The Galileo satellite navigation system has been evolving continuously, and on 11 February 2019, the constellation reached 22 active satellites, achieving a capability of standalone Precise Point Positioning (PPP) and tropospheric estimation that is global in scope. This enhancement shows a 37% improvement if the precision of the Galileo-only zenith tropospheric delay, while we may anticipate further benefits in terms of tropospheric gradients and slant delays in the future if an optimal multi-constellation and multi-frequency processing strategy is used. First, we analyze the performance of the multi-frequency troposphere estimates based on the PPP raw observation model by comparing it with the standard ionosphere-free model. The performance of the Galileo-only tropospheric solution is then validated with respect to GPS-only solution using 48 globally distributed Multi-GNSS Experiment (MGEX) stations. The averaged bias and standard deviations are −0.3 and 5.8 mm when only using GPS satellites, respectively, and 0.0 and 6.2 mm for Galileo, respectively, when compared to the International GNSS Service (IGS) final Zenith Troposphere Delay(ZTD) products. Using receiver antenna phase center corrections from the corresponding GPS dual-frequency observations does not affect the Galileo PPP ambiguity float troposphere solutions. These results demonstrate a comparable precision achieved for both Galileo-only and GPS-only ZTD solutions, however, horizontal tropospheric gradients, estimated from standalone GPS and Galileo solutions, still show larger discrepancies, mainly due to their being less Galileo satellites than GPS satellites. Including Galileo E1, E5a, E5b, and E5 signals, along with their proper observation weighting, show the benefit of multi-frequency observations, further improving the ZTD precision by 4% when compared to the dual-frequency raw observation model. Overall, the presented results demonstrate good prospects for the application of multi-frequency Galileo observations for the tropospheric parameter estimates.

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Section: Station Namementioning

confidence: 56%

Performance Evaluation of Troposphere Estimated from Galileo-Only Multi-Frequency Observations

2020

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“…(1). ZTD is derived during GPS processing, which implicitly covers satellite orbit errors, unmodeled ionospheric delays, signal multipath, antennarelated errors, e.g., antenna phase center variations (Ejigu et al 2019), and mapping function errors. ZHD is determined from uncertainties in surface pressure and the constant (2.2767 mm/hPa) as follows:…”

Section: Retrieval Of Iwv Fields From the Gps Ztdmentioning

confidence: 99%

“…Liou and Huang (2000) and Sapucci et al (2016) reported a sharp increase in GPS-IWV prior to a rainfall event. In addition, recent studies have investigated the accuracy of GPS tropospheric products by identifying factors that affect the quality of GPS processing (Kačmařík et al 2017;Klos et al 2018, Ejigu et al 2019. Furthermore, in areas where a dense network of GPS stations is available, it is possible to produce optimal GPS-IWV distribution maps to investigate spatiotemporal changes in water vapor.…”

Section: Introductionmentioning

confidence: 99%

Monitoring and prediction of hurricane tracks using GPS tropospheric products

et al. 2021

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We have reconstructed integrated water vapor (IWV) using the zenith wet delays to track the properties of hurricanes and explore their spatial and temporal distributions estimated from 922 GPS stations. Our results show that a surge in GPS-derived IWV occurred at least six hours prior to the landfall of two major hurricanes (Harvey and Irma) that struck the Gulf and East Coasts of the USA in 2017. We observed enhanced IWV, in particular, for the two hurricanes landfall locations. The observed variations exhibit a correlation with the precipitation value constructed from GPM/IMERG satellite mission coinciding with hurricane storm front passage. We used GPS-IWV data as inputs for spaghetti line plots for our path predictions, helping us predict the paths of Hurricanes Harvey and Irma. Hence, a directly estimable zenith wet delay sourced from GPS that has not been previously reported can serve as an additional resource for improving the monitoring of hurricane paths.

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“…It should be remembered here that antenna modeling impacts on all estimates, such as tropospheric delay or clocks. However, previously conducted studies on receiver antennas show that the greatest impact of using different PCCs is more visible in the height [ 23 ], and much less visible in the tropospheric parameters [ 34 , 35 ]. Therefore, in our study, we focused only on the coordinates.…”

Section: Resultsmentioning

confidence: 99%

Impact of Using GPS L2 Receiver Antenna Corrections for the Galileo E5a Frequency on Position Estimates

Araszkiewicz

Kiliszek

2020

Sensors

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Knowledge of Global Navigation Satellite System (GNSS) antenna phase center variations plays a key role in precise positioning. Proper modeling is achieved by accessing antenna phase center corrections, which are determined in the calibration process. For most receiver antenna types, the International GNSS Service provides such corrections for two GPS and GLONASS carrier signals. In the case of Galileo, access to phase center corrections is difficult; only antennas calibrated in the anechoic chambers have available corrections for Galileo frequencies. Hence, in many of the studies, GPS-dedicated corrections are used for these Galileo frequencies. Differential analysis was conducted in this study to evaluate the impact of such change. In total, 25 stations belonging to the EUREF Permanent Network and equipped with individual calibrated antennas were the subject of this research. The results for both the absolute and relative positioning methods are clear: using GPS L2 corrections for Galileo E5a frequency causes a bias in the estimated height of almost 8 mm. For the horizontal component, a significant difference can be noticed for only one type of antenna.

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Impact of GPS antenna phase center models on zenith wet delay and tropospheric gradients

Cited by 12 publications

References 22 publications

Performance Evaluation of Troposphere Estimated from Galileo-Only Multi-Frequency Observations

Performance Evaluation of Troposphere Estimated from Galileo-Only Multi-Frequency Observations

Monitoring and prediction of hurricane tracks using GPS tropospheric products

Impact of Using GPS L2 Receiver Antenna Corrections for the Galileo E5a Frequency on Position Estimates

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