Tropospheric Zenith Delay Prediction Accuracy for High‐Precision GPS Positioning and Navigation

In this paper, we determine mean bias and root‐mean‐square (RMS) scatter for a large number of zenith tropospheric propagation delay prediction models developed in the last few decades by comparing the models against ray‐tracing results using a 1‐year data set of radiosonde profiles. We conclude that the hydrostatic zenith delay can be predicted with submillimeter accuracy, provided that accurate measurements of station pressure are available. For wet zenith delay, the models differ significantly in accuracy, but show very similar RMS scatter. Our analyses show that the wet zenith delay can typically be predicted with a precision of approximately 3 cm using meteorological data. The prediction of the total delay by models typically used in airborne navigation indicates a much poorer accuracy, leading to prediction biases ranging from around 6 cm to more than 20 cm. In general, all the models tested perform significantly better at midlatitudes than at low latitudes.