Skip to main content

Research Repository

Advanced Search

The status of GNSS data processing systems to estimate integrated water vapour for use in numerical weather prediction models

Ahmed, F.; Teferle, F. N.; Bingley, R. M.; Laurichesse, D.


F. Ahmed

F. N. Teferle

D. Laurichesse


© Springer International Publishing Switzerland 2015. Modern Numerical Weather Prediction (NWP) models make use of the GNSS-derived Zenith Total Delay (ZTD) or Integrated Water Vapour (IWV) estimates to enhance the quality of their forecasts. Usually, the ZTD is assimilated into the NWP models on 3-hourly to 6-hourly intervals but with the advancement of NWP models towards higher update rates e.g. 1-hourly cycling in the Rapid Update Cycle (RUC) NWP, it has become of high interest to estimate ZTD on sub-hourly intervals. In turn, this imposes requirements related to the timeliness and accuracy of the ZTD estimates and has lead to a development of various strategies to process GNSS observations to obtain ZTD with different latencies and accuracies. Using present GNSS products and tools, ZTD can be estimated in realtime (RT), near real-time (NRT) and post-processing (PP) modes. The aim of this study is to provide an overview and accuracy assessment of various RT, NRT, and PP IWV estimation systems and comparing their achieved accuracy with the user requirements for GNSS meteorology. The NRT systems are based on Bernese GPS Software 5.0 and use a double-differencingstrategy whereas the PP system is based on the Bernese GNSS Software 5.2 using the precise point positioning (PPP) strategy. The RT systems are based on the BKG Ntrip Client 2.7 and the PPP-Wizard both using PPP. The PPP-Wizard allows integer ambiguity resolution at a single station and therefore the effect of fixing integer ambiguities on ZTD estimates will also be presented.


Ahmed, F., Teferle, F. N., Bingley, R. M., & Laurichesse, D. (2016). The status of GNSS data processing systems to estimate integrated water vapour for use in numerical weather prediction models.

Conference Name IAG 150 Years
Start Date Sep 1, 2013
End Date Sep 6, 2013
Acceptance Date Feb 3, 2014
Online Publication Date Jul 30, 2015
Publication Date Jan 1, 2016
Deposit Date Jun 17, 2016
Pages 587-593
Series Title Proceedings of the IAG Scientific Assembly
ISBN 9783319246031
Keywords Global Navigation Satellite Systems; Integrated water vapour; Near real-time; Numerical weather prediction; Post processing; Real-time; Troposphere; Zenith total delay
Public URL
Publisher URL
Copyright Statement Copyright information regarding this work can be found at the following address:
Additional Information The final publication is available at Springer via