Radiosonde-Based New Spatiotemporal Modelling for the Construction of Temperature Profiles for GNSS Applications

In order to construct temperature profiles over a GNSS station of interest, a series of spatiotemporal models for determining the ratio of the zenith dry delay (ZDD) for 40 selected pressure levels were established using a harmonic function and 18 years radiosonde data from 92 stations distributed in East Asia. The ZDD over a site is defined by the integral of the temperature profile and the dry pressure profile over the site. In the case that neither the temperature profile nor the dry pressure profile is available, a method for the ZDD obtained from precipitation water vapor (PWV) and zenith hydrostatic delay (ZHD) is derived in this study. Then, the ZDD value at a dry pressure level, named ZDD-lev, was obtained by multiplying the above ZDD with the ratio of the ZDD interpolated from the above mentioned spatiotemporal model for the level. The ZDD-lev and the dry pressure were used to determine the temperature of the level. The temperature profile was composed of the temperature values at all the dry pressure levels. The temperature profiles constructed at 10 IGS stations during a 8-year-period were evaluated using the observed ones as the references. The results indicated that the mean root-mean-square error (RMSE) and mean bias of the temperature profiles at 10 IGS stations was 3.24 K and 0.5 K, respectively.