Differential ZTD estimation based on high spatial resolution NWP data for the Nordic countries

This paper contains results from a study where Numerical Weather Product (NWP) data provided by MET Norway are used to estimate the differential zenith tropospheric delay (dZTD) for an area covering Scandinavia, Finland and the Baltic countries. The NWP data have a high spatial resolution of 2.5 × 2.5 km, and the estimated dZTD for the grid positions allow for calculation of the tropospheric gradient on short baselines. The results give an indication of how large dZTD values that can be observed for baselines up to 20 km, and where the largest events are located within the coverage area. The motivation for this investigation is to better understand the characteristics of this phenomena and how it might impact high precision and/or high integrity GNSS-based navigation systems in these regions.