Water vapor scale height is an important parameter that reflects the vertical distribution of water vapor and also a key parameter that is usually used to make height correction in GNSS zenith wet delay and tropospheric tomography. Based on the spectral analysis of the time series of water vapor scale height from 2006 to 2012, it is found that the water vapor scale height shows an annual and a semi-annual variation in time. So, the trigonometric functions with an annual and a semi-annual cycle are used to express the time variation of water vapor scale height.And then the European Centre for Medium-range Weather Forecasting (ECMWF) data are used to fit the coefficients of the trigonometric functions at 1°×1° grid points on a global scale. By these methods,a global water vapor scale height model GSH is firstly established, which considers both the time and geographic variations of water vapor scale height. By taking radiosonde data as reference, the GSH model has bias of -0.19 km and rootmean square error (RMSE) of 1.81 km; by taking ECMWF data as reference, the GSH model has bias of 0.04 km and RMSE of 1.52 km. The GSH model shows a relatively even accuracy on a global scale, and could serve the study of GNSS meteorology and provide reference values of water vapor scale height for related meteorological researches.
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