High-precision GNSS orbit, clock and EOP estimation at the United States Naval Observatory

Byram, Sharyl; Hackman, Christine

doi:10.1109/plans.2012.6236940

Cited by 10 publications

(5 citation statements)

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“…They are calculated by the PPP approach using Bernese software with an interval of 5 min and latency around 3 weeks. The GMF mapping functions and the dry Niell a priori ZHD are adopted for the modeling of tropospheric delays [Byram and Hackman, 2012].…”

Section: Igs Ztdsmentioning

confidence: 99%

Real‐time retrieval of precipitable water vapor from GPS precise point positioning

et al. 2014

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Sensing of precipitable water vapor (PWV) using the Global Positioning System (GPS) has been intensively investigated in the past 2 decades. However, it still remains a challenging task at a high temporal resolution and in the real-time mode. In this study the accuracy of real-time zenith total delay (ZTD) and PWV using the GPS precise point positioning (PPP) technique is investigated. GPS observations in a 1 month period from 20 globally distributed stations are selected for testing. The derived real-time ZTDs at most stations agree well with the tropospheric products from the International Global Navigation Satellite Systems Service, and the root-mean-square errors (RMSEs) are <13 mm, which meet the threshold value of 15 mm if ZTDs are input to numerical weather prediction models. The RMSE of the retrieved PWVs in comparison with the radiosonde-derived values are ≤3 mm, which is the threshold RMSE of PWVs as inputs to weather nowcasting. The theoretical accuracy of PWVs is also discussed, and 3 mm quality of PWVs is proved achievable in different temperature and humidity conditions. This implies that the real-time GPS PPP technique can be complementary to current atmospheric sounding systems, especially for nowcasting of extreme weather due to its real-time, all-day, and all-weather capabilities and high temporal resolutions.

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Section: Igs Ztdsmentioning

confidence: 99%

Real‐time retrieval of precipitable water vapor from GPS precise point positioning

et al. 2014

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“…The time resolution for USNO ZTD products is 5 min. The GMF model is also adopted by USNO [46]. The accuracy of the two mentioned ZTD products can be up to 4 mm with respect to the tropospheric products generated from different geodetic measurements, for instance, very long baseline interferometry (VLBI), Delft object-oriented radar interferometric software (DORIS), and radiosondes [19,45].…”

Section: Final Troposphere Productsmentioning

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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“…The sampling interval of the USNO products is 5 min, which is generated using PPP as implemented in the Bernese GPS Software Version 5.0 [Dach et al, 2007] based on the IGS final orbit/clock products. The GMF is applied at USNO [Byram and Hackman, 2012]. The accuracy of these two products is about 4 mm with respect to the troposphere results generated by other independent measurement techniques, e.g., VLBI, DORIS, radiosondes, and numerical weather models [Dow et al, 2009;Yuan et al, 2014;Dach and Jean, 2015].…”

Section: Final Troposphere Productsmentioning

confidence: 99%

An evaluation of real‐time troposphere estimation based on GNSS Precise Point Positioning

et al. 2017

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It is anticipated that the performance of real‐time (RT) GNSS meteorology can be further improved by incorporating observations from multiple Global Navigation Satellite System (GNSS), including GPS, GLONASS, Galileo, and BeiDou. In this paper, an operational RT system for extracting zenith troposphere delay (ZTD) using a modified version of the Precise Point Positioning With Integer and Zero‐difference Ambiguity Resolution Demonstrator (PPP‐WIZARD) was established. GNSS, including GPS, GLONASS, and Galileo, observation streams were processed using RT Precise Point Positioning (PPP) strategy based on RT satellite orbit/clock products from the Centre National d'Etudes Spatiales. An experiment covering 30 days was conducted, in which the observation streams of 20 globally distributed stations were processed. The initialization time and accuracy of the RT troposphere results using single‐system and multisystem observations were evaluated. The effect of PPP ambiguity resolution was also evaluated. Results reveal that RT troposphere estimates based on single‐system observations can both be applied in weather nowcasting, in which the GPS‐only solution is better than the GLONASS‐only solution. The performance can also be improved by PPP ambiguity resolution and utilizing GNSS observations. Specifically, we notice that ambiguity resolution is more effective in improving the accuracy of ZTD, whereas the initialization process can be better accelerated by GNSS observations. Combining all techniques, the RT troposphere results with an average accuracy of about 8 mm in ZTD can be achieved after an initialization process of approximately 8.5 min, which demonstrates superior results for applying GNSS observations and ambiguity resolution for RT meteorological applications.

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High-precision GNSS orbit, clock and EOP estimation at the United States Naval Observatory

Cited by 10 publications

References 1 publication

Real‐time retrieval of precipitable water vapor from GPS precise point positioning

Real‐time retrieval of precipitable water vapor from GPS precise point positioning

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

An evaluation of real‐time troposphere estimation based on GNSS Precise Point Positioning

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