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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union

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doi:10.5194/amt-2016-264
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
16 Aug 2016
Review status
A revision of this discussion paper is under review for the journal Atmospheric Measurement Techniques (AMT).
Determination of zenith hydrostatic delays and the development of new global long-term GNSS-derived precipitable water vapor
Xiaoming Wang1, Kefei Zhang1,2, Suqin Wu1, Changyong He1, Yingyan Cheng3, and Xingxing Li4 1Satellite Positioning for Atmosphere, Climate and Environment (SPACE) Research Centre, the School of Science, Mathematical and Geospatial Sciences, RMIT University, Australia
2China University of Mining and Technology, China
3Chinese Academy of Surveying and Mapping, Beijing, China
4Helmholtz-Zentrum Potsdam – Deutsches GeoForschungsZentrum GFZ, Brandenburg, Germany
Abstract. Surface pressure is a vital meteorological variable for the accurate determination of precipitable water vapor (PWV) using Global Navigation Satellite Systems (GNSS). The lack of pressure observations is a big issue for the study of climate using historical GNSS observations, which is a relatively new area of GNSS applications in climatology. Hence the use of the surface pressure derived from either an empirical model (e.g. Global Pressure and Temperature 2 wet, GPT2w) or a global atmospheric reanalysis (e.g. ERA-Interim) becomes an important alternative solution. In this study, pressure derived from these two methods is compared against the pressure observed at 108 global GNSS stations for the period 2000–2013. Results show that a good accuracy is achieved from the GPT2w-derived pressure in the latitude band of −30 to 30° and the average value of Root-Mean-Square (RMS) errors across all the stations in this region is 2.4 mb. Correspondingly, an error of 5.6 mm and 1.0 mm in its resultant zenith hydrostatic delay (ZHD) and PWV is expected. In addition, GPT2w-derived pressure usually has a larger error in the cold season due to large diurnal ranges, which is not considered in the GPT2w model. The average value of the RMS errors of the ERA-Interim-derived pressure across all the 108 stations is 1.1 mb, which will lead to an equivalent error of 2.5 mm and 0.4 mm in its resultant ZHD and PWV respectively. Our research also indicates that the ERA-Interim-derived pressure has the potential to be used as a useful meteorological data source to obtain high accuracy PWV on a global scale for climate studies and the GPT2w-derived pressure can be potentially used for climatology as well although it may be only suitable for the tropical regions.

Citation: Wang, X., Zhang, K., Wu, S., He, C., Cheng, Y., and Li, X.: Determination of zenith hydrostatic delays and the development of new global long-term GNSS-derived precipitable water vapor, Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2016-264, in review, 2016.
Xiaoming Wang et al.
Xiaoming Wang et al.

Data sets

Long-term global GPS-derived precipitable water vapor data set
X. Wang, K. Zhang, S. Wu, S. Fan, and Y. Cheng
doi:10.1002/2015JD024181
Xiaoming Wang et al.

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Short summary
Accurate knowledge of Water vapor (WV) is vital for global climate studies. Global Navigation Satellite Systems (GNSS) have been used as an emerging technique for sensing precipitable WV (PWV). In the determination of PWV, surface pressure is required. However, few GNSS stations were installed with meteorological sensors back in the 1990s. Our research indicates that the ERA-Interim-derived pressure has the potential to be used to obtain high accuracy PWV on a global scale for climate studies.
Accurate knowledge of Water vapor (WV) is vital for global climate studies. Global Navigation...
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