Assessment of ZTD derived from ECMWF/NCEP data with GPS ZTD over China

Chen, Qinming; Song, Shuli; Heise, S.; Liou, Yuei-An; Zhu, Wenyao; Zhao, Jun

doi:10.1007/s10291-010-0200-x

Cited by 88 publications

(71 citation statements)

References 15 publications

(15 reference statements)

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“…Experiments show that RMS of the tropospheric delay residuals derived from the medium-range NWP model from the SMB are between 24.02 and 32.62 mm, which is much better than that of the ECMWF and NCEP shown in the research of Chen et al [28]. However, it should be mentioned that it is not completely fair to compare the ZTD residual of them as the spatial resolutions of them are different.…”

Section: Discussionmentioning

confidence: 79%

“…Research demonstrated that the ZTD derived from the NWP model-global data acquisition system (GDAS) agreed with the IGS ZTD solutions at a 3.0 cm root mean square difference (RMSD) level with biases of up to 4.5 cm over a 1.5-year period at 18 globally distributed IGS stations [27]. The test results of [28] showed that the RMSD of the ZTD calculated by the European Centre for Medium-Range Weather Forecasts (ECMWF), reanalyzed data with a horizontal resolution of 0.5 • × 0.5 • in China, was 3.54 cm and that of the National Centers for Environmental Prediction (NCEP), with a horizontal resolution of 2.5 • × 2.5 • , was 5.36 cm. However, the tropospheric delay estimated by the reanalyzed data cannot be used in real-time positioning.…”

Section: Introductionmentioning

confidence: 85%

“…Two methods: the integral method and model estimation method, are commonly used to derive the ZTD from the NWP meteorological parameters [28]. In this study, the results of the integral method and model estimation method was compared by computing the tropospheric delay of one reference station for one year using these two methods.…”

Section: Nwp Ztd Integral Methodsmentioning

confidence: 99%

“…However, the tropospheric delay estimated by the reanalyzed data cannot be used in real-time positioning. Experimental results showed that the RMSD of the ZTD derived from NCEP surface forecast data was 10 cm over China [28]. Research also demonstrated that although independent observation showed good accuracy of the zenith hydrostatic delay (ZHD) derived from the NWP models, the accuracy of the zenith wet delay (ZWD) derived from these models was usually far less than that of the ZHD, especially in low-altitude regions [29].…”

Section: Introductionmentioning

confidence: 99%

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GPS/BDS Medium/Long-Range RTK Constrained with Tropospheric Delay Parameters from NWP Model

Chen

et al. 2018

Remote Sensing

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Tropospheric delay is a major error source that affects the performance of the Global Navigation Satellite Systems (GNSS) Real Time Kinematic (RTK) positioning especially for the medium/long-range baseline. Although high precision tropospheric delay can be estimated by GNSS carrier phase measurement, together with position and ambiguity, a relatively long period of convergence time is necessary. In this study, we develop a new GPS/BDS RTK algorithm constrained with a tropospheric delay parameters from Numerical weather prediction (NWP) model for medium/long-range baselines. The accuracy of the tropospheric delays derived from NWP is assessed through comparisons with the results of GAMIT (GNSS at MIT). The positioning performance with standard GPS RTK, standard GPS/BDS RTK, the developed NWP-constrained GPS RTK and NWP-constrained GPS/BDS RTK over medium/long-range baselines are compared in terms of the initialization time and the positioning accuracy. Experiment results show that the mean differences between the NWP and GAMIT zenith tropospheric delay (ZTD) are between −5.50 mm and 5.60 mm, and the RMS values of the NWP ZTD residuals are from 24.02 mm to 32.62 mm. A reduction in the initialization time of over 41% and 58% for medium-and long-range baselines can be achieved with the NWP-constrained RTK (both GPS alone and GPS/BDS RTK solutions) compared to the standard RTK solution, respectively. An improvement of over 30% can be found with the GPS/BDS RTK compared with that of the GPS alone RTK for both standard and the NWP-constrained modes. The positioning precision of NWP-constrained GPS/BDS RTK is better than 3 cm in the horizontal direction and better than 5 cm in the vertical direction, which satisfies the requirement of the precise positioning service.

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Section: Discussionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 85%

Section: Nwp Ztd Integral Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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GPS/BDS Medium/Long-Range RTK Constrained with Tropospheric Delay Parameters from NWP Model

Chen

et al. 2018

Remote Sensing

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“…Conventionally, the total delay of GPS radio signals along the line of sight from each satellite are mapped to the zenith direction leading to a single average parameter called the zenith total delay or zenith path delay (ZPD). ZPD is a crucial parameter for meteorological and climatological study (Kuo et al 2000;Chen et al 2011). For instance, it serves as an additional input parameter in Numerical Weather Prediction (NWP) models for synoptic meteorology, while for nowcasting; it is a standard real time product used as a measure of the state of the atmosphere (Bosy et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Preliminary Design for near Real-Time GPS Meteorology over Peninsular Malaysia (G-MeM)

Opaluwa¹,

Musa²,

Omar³

et al. 2014

Terr. Atmos. Ocean. Sci.

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This paper presents a conceptual approach for near real time Global Positioning System (GPS) meteorology in Malaysia using combined space-and ground-based GPS observations. Data from a single GPS station is utilised to derive wet refractivities for comparison with radio occultation (RO). This study shows that the wet refractivities from the ground-based GPS present similar patterns and better correlation with the radiosonde data than that from the space-based GPS RO data at altitudes between 0 -5 km. Similarly, the wet refractivities derived from RO are more highly correlated with the radiosonde data than the ground-based GPS at altitudes above 5 km. The residual N w vary from -9.25 -21.136 N-unit at 00 h UTC for the ground-based GPS while for the GPS RO, it is -19 -9.259 N-unit at 00 h UTC.

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An Analysis for the Accuracy of Tropospheric Zenith Delay Calculated From ECMWF/NCEP Data Over Asia

Chen

Song

Zhu

2012

Chinese J of Geophysics

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The tropospheric delay is an important error source for the satellite navigation and positioning, and the numerical forecast data derived from meteorological instruments can be used to calculate the tropospheric delay. In this study, the zenith tropospheric delay (ZTD) observed from 49 Global Positioning System (GPS) sites distributed in Asia was applied to assess the availability and accuracy for ZTD calculated from the European Center for Medium‐Range Weather Forecasts (ECMWF) and the United States National Centers for Environmental Prediction (NCEP). The practicability of ECMWF/NCEP data in Asia and the relation between the resolution and the accuracy for ECMWF were also studied. The results show that relative to GPS observed ZTD (GPS ZTD), the bias and rms for the ECMWF data are –1.0 cm and 2.7 cm, respectively, which are better than that for the NCEP data and can be used for ZTD study and application with high accuracy. The bias and rms for the NCEP forecast data are 2.4 cm and 6.8 cm, which are sufficed for the tropospheric delay correction in the real‐time GNSS navigation and positioning. The bias and rms exhibit a seasonal variation, which are generally of larger values in summer months and smaller values in winter months; however, the relation between the bias and rms and the latitude is not obvious, but the rms is decreasing while the altitude increasing. In addition, the daily bias and rms in eastern Asia in summer and in southern Asia in winter have a relatively larger variation. The resolutions of 2.5 degree and 0.5 degree for the ECMWF data are compared; the rms for the latter is decreased by 1~5 mm than the former. These results provide a reference for the availability and accuracy of the ECMWF/NCEP data used for calculating the tropospheric delay in the space geodesy, InSAR, navigation and positioning.

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Assessment of ZTD derived from ECMWF/NCEP data with GPS ZTD over China

Cited by 88 publications

References 15 publications

GPS/BDS Medium/Long-Range RTK Constrained with Tropospheric Delay Parameters from NWP Model

GPS/BDS Medium/Long-Range RTK Constrained with Tropospheric Delay Parameters from NWP Model

Preliminary Design for near Real-Time GPS Meteorology over Peninsular Malaysia (G-MeM)

An Analysis for the Accuracy of Tropospheric Zenith Delay Calculated From ECMWF/NCEP Data Over Asia

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