Evaluation of Zenith Tropospheric Delay Derived from ERA5 Data over China Using GNSS Observations

Jiang, Chunhua; Xu, Tianhe; Wang, Shuaimin; Nie, Wenfeng; Sun, Zhangzhen

doi:10.3390/rs12040663

Cited by 44 publications

(27 citation statements)

References 39 publications

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“…However, there are few studies of the applicability of multiple reanalysis products on a global scale. As the latest ECMWF atmospheric reanalysis products, the fifth generation of ECMWF Reanalysis (ERA5) has the highest temporal and spatial resolution, and has been used in the past two years [43]. The accuracy of ERA5 has not been verified worldwide, and a comparison between ERA5 and other reanalysis products has not been made.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Precipitable Water Vapor from Five Reanalysis Products with Ground-Based GNSS Observations

Wang

Nie

et al. 2020

Remote Sensing

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At present, the global reliability and accuracy of Precipitable Water Vapor (PWV) from different reanalysis products have not been comprehensively evaluated. In this study, PWV values derived by 268 Global Navigation Satellite Systems (GNSS) stations around the world covering the period from 2016 to 2018 are used to evaluate the accuracies of PWV values from five reanalysis products. The temporal and spatial evolution is not taken into account in this analysis, although the temporal and spatial evolution of atmospheric flows is one of the most important information elements available in numerical weather prediction products. The evaluation results present that five reanalysis products with PWV accuracy from high to low are in the order of the fifth generation of European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis (ERA5), ERA-Interim, Japanese 55-year Reanalysis (JRA-55), National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR), and NCEP/DOE (Department of Energy) according to root mean square error (RMSE), bias and correlation coefficient. The ERA5 has the smallest RMSE value of 1.84 mm, while NCEP/NCAR and NCEP/DOE have bigger RMSE values of 3.34 mm and 3.51 mm, respectively. The findings demonstrate that ERA5 and two NCEP reanalysis products have the best and worst performance, respectively, among five reanalysis products. The differences in the accuracy of the five reanalysis products are mainly attributed to the differences in the spatial resolution of reanalysis products. There are some large absolute biases greater than 4 mm between GNSS PWV values and the PWV values of five reanalysis products in the southwest of South America and western China due to the limit of terrains and fewer observations. The accuracies of five reanalysis products are compared in different climatic zones. The results indicate that the absolute accuracies of five reanalysis products are highest in the polar regions and lowest in the tropics. Furthermore, the effects of different seasons on the accuracies of five reanalysis products are also analyzed, which indicates that RMSE values of five reanalysis products in summer and in winter are the largest and the smallest in the temperate regions. Evaluation results from five reanalysis products can help us to learn more about the advantages and disadvantages of the five released water vapor products and promote their applications.

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Section: Introductionmentioning

confidence: 99%

Evaluation of Precipitable Water Vapor from Five Reanalysis Products with Ground-Based GNSS Observations

Wang

Nie

et al. 2020

Remote Sensing

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“…According to the results of validation, the ERA5-derived air temperature is highly consistent with monitoring measurements in nationwide China, with the annual average RMS (i.e. Root Mean Square) equal to 2.31 °C [ 51 ]. Such high consistencies with ground observations have also been reported for several climatic variables derived from the ERA5 product [ 20 , 52 ].…”

Section: Methodsmentioning

confidence: 73%

Climatic modification effects on the association between PM1 and lung cancer incidence in China

Guo

Liu

et al. 2021

BMC Public Health

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Background Nationwide studies that examine climatic modification effects on the association between air pollution and health outcome are limited in developing countries. Moreover, few studies focus on PM1 pollution despite its greater health effect. Objectives This study aims to determine the modification effects of climatic factors on the associations between PM1 and the incidence rates of lung cancer for males and females in China. Methods We conducted a nationwide analysis in 345 Chinese counties (districts) from 2014 to 2015. Mean air temperature and relative humidity over the study period were used as the proxies of climatic conditions. In terms of the multivariable linear regression model, we examined climatic modification effects in the stratified and combined datasets according to the three-category and binary divisions of climatic factors. Moreover, we performed three sensitivity analyses to test the robustness of climatic modification effects. Results We found a stronger association between PM1 and the incidence rate of male lung cancer in counties with high levels of air temperature or relative humidity. If there is a 10 μg/m3 shift in PM1, then the change in male incidence rate relative to its mean was higher by 4.39% (95% CI: 2.19, 6.58%) and 8.37% (95% CI: 5.18, 11.56%) in the middle and high temperature groups than in the low temperature group, respectively. The findings of climatic modification effects were robust in the three sensitivity analyses. No significant modification effect was discovered for female incidence rate. Conclusions Male residents in high temperature or humidity counties suffer from a larger effect of PM1 on the incidence rate of lung cancer in China. Future research on air pollution-related health impact assessment should consider the differential air pollution effects across different climatic conditions.

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“…Moreover, precise estimates of tropospheric delay can as well be utilised to infer precipitable water vapour (PWV) in the atmosphere with high spatial and temporal resolution [5,6]. Information about the retrieved PWV is essential for numerical weather prediction (NWP) such as weather forecasts and nowcasting, climate change research, and other atmospheric studies [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…Due to the high inhomogeneous spatial and temporal variation in water vapour content in the atmosphere, precise modelling of tropospheric delay has been a major challenge to researchers in the GNSS community [11]. For this reason, several approaches and models have evolved over the years towards the quantification and mitigation of tropospheric delay [8].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Zenith Tropospheric Delay Derived from Ray-Traced VMF3 Product over the West African Region Using GNSS Observations

Osah

Acheampong

Fosu

et al. 2021

Advances in Meteorology

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The growing demand for Global Navigation Satellite System (GNSS) technology has necessitated the establishment of a vast and ever-growing network of International GNSS Service (IGS) tracking stations worldwide. The IGS provides highly accurate and highly reliable daily time-series Zenith Tropospheric Delay (ZTD) products using data from the member sites towards the use of GNSS for precise geodetic, climatological, and meteorological applications. However, if for reasons like poor internet connectivity, equipment failure, and power outages, the IGS station is inaccessible or malfunctioning, and gaps are created in the data archive resulting in degrading the quality of the ZTD and precipitable water vapour (PWV) estimation. To address this challenge as a means of providing an alternative data source to improve the continuous availability of ZTD data and as a backup data in the event that the IGS site data are missing or unavailable in West Africa, this paper compares the sitewise operational Vienna Mapping Functions 3 (VMF3) ZTD product with the IGS final ZTD product over five IGS stations in West Africa. Eight different statistical evaluation metrics, such as the mean bias (MB), mean absolute error (MAE), root mean squared error (RMSE), Pearson correlation coefficient (r), coefficient of determination (r2), refined index of agreement (IAr), Nash–Sutcliffe coefficient of efficiency (NSE), and the fraction of prediction within a factor of two (FAC2), are employed to determine the degree of agreement between the VMF3 and IGS tropospheric products. The results show that the VMF3-ZTD product performed excellently and matches very well with the IGS final ZTD product with an average MB, MAE, RMSE, r, r2, NSE, IAr, and FAC2 of 0.38 cm, 0.87 cm, 1.11 cm, 0.988, 0.976, 0.967, 0.992, and 1.00 (100%), respectively. This result is an indication that the VMF3-ZTD product is accurate enough to be used as an alternative source of ZTD data to augment the IGS final ZTD product for positioning and meteorological applications in West Africa.

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Evaluation of Zenith Tropospheric Delay Derived from ERA5 Data over China Using GNSS Observations

Cited by 44 publications

References 39 publications

Evaluation of Precipitable Water Vapor from Five Reanalysis Products with Ground-Based GNSS Observations

Evaluation of Precipitable Water Vapor from Five Reanalysis Products with Ground-Based GNSS Observations

Climatic modification effects on the association between PM1 and lung cancer incidence in China

Evaluation of Zenith Tropospheric Delay Derived from Ray-Traced VMF3 Product over the West African Region Using GNSS Observations

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