Meteorological products derived from Global Navigation Satellite Systems (GNSS) observations have been routinely used for numerical weather prediction in several regions of the world. Hungary would like to join these activities exploiting meteorological usage of the dense GNSS CORS (Continuously Operating Reference Station) network operated by the Institute of Geodesy, Cartography and Remote Sensing for positioning applications.
This paper introduces the near real-time processing system of GNSS observations for meteorological purposes in Hungary. The hourly observations of 35 Hungarian permanent GNSS CORSs are processed. This network is extended beyond the country with about 50 stations covering Eastern and Central Europe. The data analysis is being done using the Bernese V5.0 GPS data processing software. The Hungarian CORS network has an average baseline length of 60 km, thus the precipitable water vapour (PW) can be estimated with a high spatial resolution.
The estimation of the PW from the zenith wet delay (ZWD) is carried out in near real-time. Firstly, the zenith hydrostatic delays (ZHD) are subtracted from the total delays. The wet delays are then scaled to precipitable water vapour values.
The GNSS derived PW values were validated using radiosonde observations over Central Europe using the observations of a 47-day-long period (April 14–May 31, 2011). The results showed that the estimated PW values agree with radiosonde observations at the level of ±1.5 mm in terms of standard deviation. In this comparison a bias of +1.0 mm was observed. Following the validation phase, our analysis will be connected to the continental E-GVAP project (GNSS Water Vapour Programme of the Network of European Meteorological Services, EUMETNET).
- GNSS meteorology
- Integrated water vapour
- Numerical weather prediction