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Abstract:
In the GNSS analysis the signal travel time delay induced by the neutral atmosphere is parameterized. The related parameters are derived from a climatology or better yet from a Numerical Weather Model (NWM). Current thinking is that NWMs are not accurate enough to predict the key tropospheric delay parameters, in particular those related to the variable humidity field, so that the benefit of NWM data in the GNSS analysis is limited [1]. In this contribution we investigate to which extent the assimilation of GNSS Zenith Total Delays (ZTDs) from a station network improves the NWM humidity field and hence the tropospheric delay parameters derived from it. To start with we run the Weather Research and Forecasting (WRF) Data Assimilation (DA) system at the horizontal resolution of 10 km and assimilate GNSS ZTDs for a period of two months (warm season) in Germany. Then we select the target stations (which are surrounded by a sufficiently number of other stations), analyse the impact of the assimilation on the station specific tropospheric delay parameters and estimate the impact in Precise Point Positioning (PPP).
Reference: Zus, F.; Balidakis, K.; Dick, G.; Wilgan, K.; Wickert, J. Impact of Tropospheric Mismodelling in GNSS Precise Point Positioning: A Simulation Study Utilizing Ray-Traced Tropospheric Delays from a High-Resolution NWM. Remote Sens. 2021, 13, 3944. https://doi.org/10.3390/rs13193944
