Real-Time Tropospheric Delays Retrieved from Multi-GNSS Observations and IGS Real-Time Product Streams

Lu, Cuixian; Chen, Xinghan; Liu, Gen; Dick, Galina; Wickert, Jens; Jiang, Xinyuan; Zheng, Kai; Schuh, Harald

doi:10.3390/rs9121317

Cited by 45 publications

(30 citation statements)

References 24 publications

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“…However, this is expected to be improved with new BDS satellites launched into orbit and a more densified tracking network in the near future [19,38]. In addition, although the RMS values of the along-track and cross-track components are larger than those of the radial component, the positioning users on the Earth's surface are less sensitive to errors in along-track and cross-track directions than to those in the radial direction; the orbit errors in the along-track and cross-track directions may therefore have a less significant impact on the accuracy of user positioning [24].…”

Section: Discussionmentioning

confidence: 99%

“…2018, 10, 337 4 of 19 In order to transform the RAC corrections into ECEF corrections, the transformation matrix R has to be computed first; it is expressed as [18]: Following this, the ECEF orbit corrections δX t for epoch t can be derived by:…”

Section: Computation Methods Of Real-time Precise Satellite Orbits Andmentioning

confidence: 99%

“…In this work, the chosen reference satellites are PRN#G32 for GPS, PRN#R24 for GLONASS, PRN#E30 for GALILEO, and PRN#C14 for BDS. The standard deviation (STD) value of each satellite clock, which has a significant impact on PPP results, is taken as the quality indicator to evaluate the accuracy of the satellite clock [19,25]. In addition, the RMS values of clock differences are also computed.…”

Section: Evaluation Of Real-time Precise Satellite Orbits and Clocks mentioning

confidence: 99%

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Validation and Assessment of Multi-GNSS Real-Time Precise Point Positioning in Simulated Kinematic Mode Using IGS Real-Time Service

Wang

et al. 2018

Remote Sensing

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Precise Point Positioning (PPP) is a popular technology for precise applications based on the Global Navigation Satellite System (GNSS). Multi-GNSS combined PPP has become a hot topic in recent years with the development of multiple GNSSs. Meanwhile, with the operation of the real-time service (RTS) of the International GNSS Service (IGS) agency that provides satellite orbit and clock corrections to broadcast ephemeris, it is possible to obtain the real-time precise products of satellite orbits and clocks and to conduct real-time PPP. In this contribution, the real-time multi-GNSS orbit and clock corrections of the CLK93 product are applied for real-time multi-GNSS PPP processing, and its orbit and clock qualities are investigated, first with a seven-day experiment by comparing them with the final multi-GNSS precise product 'GBM' from GFZ. Then, an experiment involving real-time PPP processing for three stations in the Multi-GNSS Experiment (MGEX) network with a testing period of two weeks is conducted in order to evaluate the convergence performance of real-time PPP in a simulated kinematic mode. The experimental result shows that real-time PPP can achieve a convergence performance of less than 15 min for an accuracy level of 20 cm. Finally, the real-time data streams from 12 globally distributed IGS/MGEX stations for one month are used to assess and validate the positioning accuracy of real-time multi-GNSS PPP. The results show that the simulated kinematic positioning accuracy achieved by real-time PPP on different stations is about 3.0 to 4.0 cm for the horizontal direction and 5.0 to 7.0 cm for the three-dimensional (3D) direction.

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Section: Discussionmentioning

confidence: 99%

Section: Computation Methods Of Real-time Precise Satellite Orbits Andmentioning

confidence: 99%

Section: Evaluation Of Real-time Precise Satellite Orbits and Clocks mentioning

confidence: 99%

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Validation and Assessment of Multi-GNSS Real-Time Precise Point Positioning in Simulated Kinematic Mode Using IGS Real-Time Service

Wang

et al. 2018

Remote Sensing

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“…Multi-GNSS observations have been intensively used to improve the precision of the tropospheric parameters retrieved from the PPP technique. Lu et al [11] evaluated the performance of the real-time ZTD estimated from single and multi-GNSS observations, and the results indicated that the precision and reliability of the troposphere estimates could be improved by using multi-GNSS data. Lu et al [12] further demonstrated that the initialization time and the precision of multi-GNSS tropospheric delays could be improved by using the PPP ambiguity-fixing technique, which can meet the requirements of the troposphere estimates for time-critical meteorological applications.…”

Section: Introductionmentioning

confidence: 99%

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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“…Significant development has been achieved in the past few years [2][3][4][5][6][7][8]. In comparison with established atmospheric sounding techniques, GPS has extensive application prospects for sounding water vapor since it has the unique advantages of all-weather availability, high accuracy, long-term stability, and high time resolution [9,10].…”

Section: Introductionmentioning

confidence: 99%

Real-Time Tropospheric Delay Retrieval from Multi-GNSS PPP Ambiguity Resolution: Validation with Final Troposphere Products and a Numerical Weather Model

Cheng

et al. 2018

Remote Sensing

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Abstract:The multiple global navigation satellite systems (multi-GNSS) bring great opportunity for the real-time retrieval of high-quality zenith tropospheric delay (ZTD), which is a critical quality for atmospheric science and geodetic applications. In this contribution, a multi-GNSS precise point positioning (PPP) ambiguity resolution (AR) analysis approach is developed for real-time tropospheric delay retrieval. To validate the proposed multi-GNSS ZTD estimates, we collected and processed data from 30 Multi-GNSS Experiment (MGEX) stations; the resulting real-time tropospheric products are evaluated by using standard post-processed troposphere products and European Centre for Medium-Range Weather Forecasts analysis (ECMWF) data. An accuracy of 4.5 mm and 7.1 mm relative to the Center for Orbit Determination in Europe (CODE) and U.S. Naval Observatory (USNO) products is achievable for real-time tropospheric delays from multi-GNSS PPP ambiguity resolution after an initialization process of approximately 5 min. Compared to Global Positioning System (GPS) results, the accuracy of retrieved zenith tropospheric delay from multi-GNSS PPP-AR is improved by 16.7% and 31.7% with respect to USNO and CODE final products. The GNSS-derived ZTD time-series exhibits a great agreement with the ECMWF data for a long period of 30 days. The average root mean square (RMS) of the real-time zenith tropospheric delay retrieved from multi-GNSS PPP-AR is 12.5 mm with respect to ECMWF data while the accuracy of GPS-only results is 13.3 mm. Significant improvement is also achieved in terms of the initialization time of the multi-GNSS tropospheric delays, with an improvement of 50.7% compared to GPS-only fixed solutions. All these improvements demonstrate the promising prospects of the multi-GNSS PPP-AR method for time-critical meteorological applications.

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Real-Time Tropospheric Delays Retrieved from Multi-GNSS Observations and IGS Real-Time Product Streams

Cited by 45 publications

References 24 publications

Validation and Assessment of Multi-GNSS Real-Time Precise Point Positioning in Simulated Kinematic Mode Using IGS Real-Time Service

Validation and Assessment of Multi-GNSS Real-Time Precise Point Positioning in Simulated Kinematic Mode Using IGS Real-Time Service

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

Real-Time Tropospheric Delay Retrieval from Multi-GNSS PPP Ambiguity Resolution: Validation with Final Troposphere Products and a Numerical Weather Model

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