EGMAP: Exploitation of GNSS tropospheric gradients for severe weather Monitoring And Prediction

Global Navigation Satellite System (GNSS) has revolutionized positioning, navigation, and timing, becoming a common part of our everyday life. A geophysical key application is atmospheric water vapor monitoring. Currently, data from European GNSS networks are operationally used to improve weather forecasts. However, the impact of the GNSS Zenith Total Delays (ZTDs) in the forecast systems are limited due to its limited atmospheric information content. The project EGMAP funded by DFG will pioneer the development and usage of next generation data products; tropospheric gradients (Fig. 1). The new data products are expected to improve Numerical Weather Prediction (NWP).


The main innovations which will be addressed by the project are (Fig. 2):

  1. Provide GNSS-ZTDs and tropospheric gradients in near-real-time and setting up of a publicly accessible monitoring system.
  2. Implement new operators in the variational/ensemble data assimilation system of the Weather Research and Forecasting (WRF) model.
  3. Conduct impact studies with data from a network of GNSS stations using advanced data assimilation techniques with the state-of-the-art NWP model.


Skamarock, W.C.; Klemp, J.B.; Dudhia, J.; Gill, D.O.; Barker, D.M.; Duda, M.G.; Huang, X.Y.; Wang, W.; Powers, J.G. A Description of the Advanced Research WRF Version 3; NCAR tech. note NCAR/TN-475+STR; NCAR: Boulder, CO, USA, 2008.

Zus, F., G. Dick, S. Heise, and J. Wickert (2015), A forward operator and its adjoint for GPS slant total delays, Radio Sci., 50, pp. 393-405,

Zus, F.; Douša, J.; Kačmařík, M.; Václavovic, P.; Dick, G.; Wickert, J. Estimating the Impact of Global Navigation Satellite System Horizontal Delay Gradients in Variational Data Assimilation. Remote Sens. 2019, 11, 41.

Link to GEPRIS project data base of DFG:

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