Tropospheric Delay estimation using constrained ray-tracing method based on surface meteorological parameters and Numerical Weather Models

Ray-tracing is a solution for tropospheric delay estimation, which recently has found an important role in space geodesy techniques. There are different data sets, which can be considered as input of this method, for example numerical weather models, rdiosonde observations and direct measurements. We have developed a constrained ray-tracing method for estimation of tropospheric total delay based on surface meteorological parameters, radiosonde observations and numerical weather models. We show results of two different methods (regional and zonal) and compare with ray-tracing using only numerical weather models. We can find that discrepancies between these methods come mainly from nonhydrostatic component, which means uncertainty in wet observations. In addition, as validation of methods, we compare our results with results of a comparison campaign, which was carried in first half of 2010 under umbrella of the IAG working group 4.3.3. The comparison shows an agreement between results, particularly in terms of slant factors.