An Accurate Height Reduction Model for Zenith Tropospheric Delay Correction Using ECMWF Data

Tropospheric delay is a major error source in geodetic techniques. In recent years, the Numerical Weather Models (NWMs), such as the European Centre for Medium Range Weather Forecasts (ECMWF), have been increasingly used in the atmospheric delay processing of space geodetic observations. It is necessary for the GNSS users to make height reduction for the troposphere products from ECMWF to obtain the accurate Zenith Tropospheric Delay (ZTD). Based on the ECMWF data, a new height reduction model for ZTD called Gaussian function model is proposed, which is suitable for the ZTD correction from ECMWF data. The internal accuracy of the proposed model is 0.9 cm. The validation by the troposphere products of 162 globally distributed IGS stations at 2015 shows that the annual average bias and Root Mean Square error (RMS) of the Gaussian function model are 0.14 and 1.55 cm respectively, and the Gaussian function model is stable throughout the year. The testing results from the ZTD profiles derived from radiosonde data shows that, the Gaussian function model performs well above 5 km height.