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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 34, issue 9
Ann. Geophys., 34, 789–799, 2016
https://doi.org/10.5194/angeo-34-789-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 34, 789–799, 2016
https://doi.org/10.5194/angeo-34-789-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Regular paper 20 Sep 2016

Regular paper | 20 Sep 2016

Optimization of GPS water vapor tomography technique with radiosonde and COSMIC historical data

Shirong Ye1, Pengfei Xia1, and Changsheng Cai2 Shirong Ye et al.
  • 1GNSS Research Centre, Wuhan University, Wuhan, 430079, China
  • 2School of Geosciences and Info-physics, Central South University, Changsha, 410083, China

Abstract. The near-real-time high spatial resolution of atmospheric water vapor distribution is vital in numerical weather prediction. GPS tomography technique has been proved effectively for three-dimensional water vapor reconstruction. In this study, the tomography processing is optimized in a few aspects by the aid of radiosonde and COSMIC historical data. Firstly, regional tropospheric zenith hydrostatic delay (ZHD) models are improved and thus the zenith wet delay (ZWD) can be obtained at a higher accuracy. Secondly, the regional conversion factor of converting the ZWD to the precipitable water vapor (PWV) is refined. Next, we develop a new method for dividing the tomography grid with an uneven voxel height and a varied water vapor layer top. Finally, we propose a Gaussian exponential vertical interpolation method which can better reflect the vertical variation characteristic of water vapor. GPS datasets collected in Hong Kong in February 2014 are employed to evaluate the optimized tomographic method by contrast with the conventional method. The radiosonde-derived and COSMIC-derived water vapor densities are utilized as references to evaluate the tomographic results. Using radiosonde products as references, the test results obtained from our optimized method indicate that the water vapor density accuracy is improved by 15 and 12 % compared to those derived from the conventional method below the height of 3.75 km and above the height of 3.75 km, respectively. Using the COSMIC products as references, the results indicate that the water vapor density accuracy is improved by 15 and 19 % below 3.75 km and above 3.75 km, respectively.

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The near-real-time high spatial resolution of atmospheric water vapor distribution is vital in numerical weather prediction. GPS tomography technique has been proved effectively for three-dimensional water vapor reconstruction. In this study, the tomography processing is optimized in a few aspects by the aid of radiosonde and COSMIC historical data, including the accuracy improvement of tropospheric zenith hydrostatic delay and precipitable water vapor conversion factor.
The near-real-time high spatial resolution of atmospheric water vapor distribution is vital in...
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