Enhanced GNSS tropospheric delay parameters for nowcasting applications

Short Description

Starting point / motivation

Currently, no comprehensive assessment of advanced near real-time (NRT) and real-time (RT) GNSS processing strategies for enhanced GNSS tropospheric delay parameter estimation (zenith delays, gradients, slant delays and refractivity fields) exists. In consequence, their potential benefit for very short-range forecasting and nowcasting applications, especially the impact of slant delays or zenith delays derived from GNSS mass-market receivers, is unknown.

However, since the establishment of new operational GNSS processing and assimilation routines is rather costly and time-consuming, within this exploratory project various scenarios for new operational services will be assessed.

Contents and goals

First, existing NRT and RT multiGNSS satellite orbit and clock products will be analysed and state of the art GNSS processing routines will be applied to multi-GNSS single- and dual-frequency observations for enhanced tropospheric delay parameter estimation.


The quality of the obtained time series will be evaluated by intra- and inter-technique comparisons. At the same time the data will be prepared for assimilation into the AROME model, using a rapid assimilation system. Therefore, the existing software solutions have to be extended for enhanced GNSS tropospheric delay parameter estimation, quality assessment, assimilation of slant delays and bias correction. By making use of the software routines, performance analyses will be carried out, which will allow for evaluating the impact of the individual GNSS products on the short-range weather forecast.

One of the strengths of the project is the inter-disciplinary collaboration of Austrian and Swiss geodetic and meteorological institutions, which will allow an efficient work on the project tasks within the short time frame.

Expected results

Based on the outcome, the direction of further developments in GNSS data processing and assimilation of GNSS derived asymmetry information in nowcasting systems, especially in Alpine areas, will be defined. This information will be of interest in particular for the meteorological and geodetic communities. In case of a positive evaluation, the development of more efficient GNSS processing and assimilation strategies, for close to real-time applications, will be stimulated.

The gained knowledge will be shared and discussed in publications in peer reviewed scientific journals and presentations at international workshops and conferences. Moreover, GNSSnow will create the scientific expertise and the capacities for further successful applications in European research programmes.

Project Partners


TU Wien - Department für Geodäsie und Geoinformation

Project partner

  • ETH Zürich
  • Zentralanstalt f. Meteorologie und Geodynamik

Contact Address

Vienna University of Technology
Department of Geodesy and Geoinformation
Dipl.-Ing. Dr.techn. Robert Weber
Gußhausstraße 27-29/E120-4
A-1040 Wien