A Comprehensive Evaluation and Analysis of the Performance of Multiple Tropospheric Models in China Region

Tropospheric path delay is an important error source in range measurements of many Earth observation systems. In this paper, the accuracies of 9 zenith hydrostatic delay (ZHD) and 18 zenith wet delay (ZWD) models are assessed using benchmark values derived from 10 years (2003-2012) of radiosonde data recorded at 92 stations in the China region. Our study confirms that ZHD can be well modeled with an accuracy of several millimeters by using surface meteorological observations. ZHD derived from the European Center for Medium-Range Weather Forecasts (ECMWF) has the best agreement of 2.8 mm with the radiosonde data in the China region, while the Baby ZHD model achieves the second best with an accuracy of 6.0 mm. All of the ZWD models can only estimate the ZWD with an accuracy of a few centimeters. ECMWF can provide ZWD estimation with the best accuracy of 21.4 mm, followed by the Baby semiempirical, Hopfield, Goad and Goodman, Askne and Nordius, Saastamoinen, Callahan, and Berman 74 ZWD models whose errors are below 40 mm. We find that in the China region all of the ZWD models perform better in winter than in summer and have higher accuracy in high latitudes than low latitudes. The performances of the 18 ZWD models are further validated in a Global Positioning System (GPS) precise point positioning (PPP) computation at 6 GPS stations in China. The PPP results also confirm that ECMWF is the best model. Considering its performance and simplicity, we conclude that Saastamoinen is the optimal ZWD model for the China region.