Tropospheric Zenith Wet and Hydrostatic Delay Models for the ESA Galileo Testbed: Models Based on Meteorological Measurements and a Blind Model

摘要

Three types of zenith wet delay (ZWD) and zenith hydrostatic delay (ZHD) models are developed. Two models require meteorological observations at the site position and are based on the Ifadis and the Hopfield ZWD model. The difference to the classical approach is that the model coefficients depend on geographical position and time and are estimated from the GDAS numerical weather model. The third model is a blind model making no use of meteorological observations. The blind model is also derived from the GDAS weather model by modeling meteorological quantities as a mean value and a seasonal variation on a global grid with 1°×1° resolution. All models provide an error bound. The models are compared against IGS zenith total delay (ZTD) values for 36 IGS stations. The mean RMS difference is 28.4 mm for the improved Hopfield ZTD model, 34.6 mm for the improved Ifadis ZTD model and 38.3 mm for the blind ZTD model.