GTm-III: a new global empirical model for mapping zenith wet delays onto precipitable water vapour

Yao, Yibin; Xu, Chaoqian; Bao, Zhenan; Cao, Na

doi:10.1093/gji/ggu008

Cited by 66 publications

(40 citation statements)

References 13 publications

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“…This finding is consistent with recent studies, (e.g. He et al, 2013;Chen et al, 2014;Yao et al, 2014a). It may be explained by the fact that the T m on the pressure levels under the terrain of Antarctica (∼ 6 km) may contain large systematic biases caused by the extrapolation of actual meteorological records.…”

Section: Comparison With Ncep2 Datasupporting

confidence: 92%

“…The GWMT series models are global models developed and consistently improved by Yao et al using the state-of-the-art data sources and improved methodologies (Yao et al, , 2014a(Yao et al, , b, 2013(Yao et al, , 2012.…”

Section: B3 Gwmt Series Modelsmentioning

confidence: 99%

“…The RMSE of T m over the ground is around 4.6 K. However, due to its poor performance in the southern Pacific Ocean, the coefficients were recalculated for an updated model -GTm-II using T m over the ocean calculated from the Bevis formula, where T s is derived from the GPT model . This GTm-II model was further improved into GTm-III using GGOS surface T m by taking semi-annual and diurnal variations of T m into account (Yao et al, 2014a). In the later GWMT-IV model, the T m lapse rate is considered as a function of geodetic coordinates instead of a constant value adopted in the former models (He et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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A new voxel-based model for the determination of atmospheric weighted mean temperature in GPS atmospheric sounding

Hé

Wang

et al. 2017

Atmos. Meas. Tech.

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Abstract. The Global Positioning System (GPS) is a powerful atmospheric observing system for determining precipitable water vapour (PWV). In the detection of PWV using GPS, the atmospheric weighted mean temperature (T m ) is a crucial parameter for the conversion of zenith tropospheric delay (ZTD) to PWV since the quality of PWV is affected by the accuracy of T m . In this study, an improved voxel-based T m model, named GWMT-D, was developed using global reanalysis data over a 4-year period from 2010 to 2013 provided by the United States National Centers for Environmental Prediction (NCEP). The performance of GWMT-D was assessed against three existing empirical T m models -GTm-III, GWMT-IV, and GTm_N -using different data sources in 2014 -the NCEP reanalysis data, surface T m data provided by Global Geodetic Observing System and radiosonde measurements. The results show that the new GWMT-D model outperforms all the other three models with a root-meansquare error of less than 5.0 K at different altitudes over the globe. The new GWMT-D model can provide a practical alternative T m determination method in real-time GPS-PWV remote sensing systems.

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Section: Comparison With Ncep2 Datasupporting

confidence: 92%

Section: B3 Gwmt Series Modelsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A new voxel-based model for the determination of atmospheric weighted mean temperature in GPS atmospheric sounding

Hé

Wang

et al. 2017

Atmos. Meas. Tech.

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“…If NWP data are not available and T m is obtained from surface temperature, the Bevis model used in this study has its disadvantages as it is based on radiosonde data from North American only [Bevis et al, 1994]. The global empirical model by Yao et al [2014] and linear station-specific regression approach based on a temperature data set by Ross and Rosenfeld [1997] are beneficial in this context.…”

Section: Discussionmentioning

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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“…In 2014, Yao et al [17] analyzed the relationship between Tm and multiple meteorological parameters and thus established the very accurate one-/ multi-parameter-based models. Yao et al [18] also published the latest and the most accurate empirical model in the same year. We can come to such conclusions from previous studies: it is of practical applicability to use Ts to calculate Tm according to regression relation; Tm À Ts regression relation has evident regional characteristics; different data have significant influence on the establishment of Tm À Ts linear relation.…”

Section: Introductionmentioning

confidence: 99%

Establishment and analysis of global gridded Tm − Ts relationship model

Lan

Bao

Geng

2016

Geodesy and Geodynamics

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Available online xxx Keywords:Zenith wet delay Precipitable water vapor Ground-based GPS meteorology Weighted mean temperature Gridded Tm À Ts model a b s t r a c tIn ground-based GPS meteorology, Tm is a key parameter to calculate the conversion factor that can convert the zenith wet delay (ZWD) to precipitable water vapor (PWV). It is generally acknowledged that Tm is in an approximate linear relationship with surface temperature Ts, and the relationship presents regional variation. This paper employed sliding average method to calculate correlation coefficients and linear regression coefficients between Tm and Ts at every 2 Â 2.5 grid point using Ts data from European Centre for Medium-Range Weather Forecasts (ECMWF) and Tm data from "GGOS Atmosphere", yielding the grid and bilinear interpolation-based TmGrid model. Tested by Tm and Ts grid data, Constellation Observation System of Meteorology, Ionosphere, and Climate (COSMIC) data and radiosonde data, the TmGrid model shows a higher accuracy relative to the Bevis Tm À Ts relationship which is widely used nowadays. The TmGrid model will be of certain practical value in high-precision PWV calculation.

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GTm-III: a new global empirical model for mapping zenith wet delays onto precipitable water vapour

Cited by 66 publications

References 13 publications

A new voxel-based model for the determination of atmospheric weighted mean temperature in GPS atmospheric sounding

A new voxel-based model for the determination of atmospheric weighted mean temperature in GPS atmospheric sounding

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

Establishment and analysis of global gridded Tm − Ts relationship model

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