The research collects data from a GNSS receiver mounted on the Snowdon Mountain Railway train, to improve airborne kinematic GNSS positioning.

As flying heights increase, atmospheric conditions at the reference and roving receivers differ and cannot be removed by data differencing, and therefore must be modelled or estimated to avoid up to 20 cm GNSS aircraft height errors. By collecting data from a GNSS receiver mounted on the Snowdon Mountain Railway train which travels on a repeatable ground track but through a height difference of 1000 m, similar to an aircraft flying height, different GNSS tropospheric mitigation approaches are evaluated in order to improve airborne kinematic GNSS positioning. These include using empirical models that attempt to predict meteorological parameters, extrapolation from the ground, and estimating the tropospheric delay using the GNSS data directly.



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