An overview of the UNB Ray-Tracer for geodetic applications

English Abstract:

Ray-tracing through the neutral-atmosphere is an important task to retrieve meteorological parameters from a numerical model. There are several ways of doing it, which implies different representations of the neutral-atmosphere, as well as different ways to integrate through the path. We have developed a ray-tracer that involves alternative models for the ray-path and the atmospheric structure involved in the operation. The ray-tracer is currently in continuous use in the evaluation of zenith delay and one of the Marini coefficients of the Vienna Mapping Functions, generated daily at UNB as a service towards GGOS. This paper overviews the main characteristics of the UNB Ray-Tracer and discusses applications when dealing with integration through numerical weather models for neutral-atmospheric delay modelling. The paper also discusses other uses of ray-tracing in geodesy.