EGU21-9087, updated on 04 Mar 2021
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

 Ground-based GNSS for climate research: review and perspectives

Rosa Pacione1, Marcelo Santos2, Galina Dick3, Jonathan Jones4, Eric Pottiaux5, Annette Rinke6, Roeland Van Malderen7, and Gunnar Elgered8
Rosa Pacione et al.
  • 1e-Geos/ASI-CGS, Matera, Matera, Italy (
  • 2University of New Brunswick Fredericton, Canada (
  • 3GFZ German Research Centre for Geosciences, Potsdam, Germany (
  • 4Met Office, Exeter, United Kingdom (
  • 5Royal Observatory of Belgium, Brussels, Belgium (
  • 6Alfred Wegener Institute, Potsdam, Germany (
  • 7Royal Meteorological Institute of Belgium, Brussels, Belgium (
  • 8Chalmers University of Technology, Onsala, Sweden (

In climate research, the role of water vapour can hardly be overestimated. Water vapour is the most important natural greenhouse gas and is responsible for the largest known feedback mechanism for amplifying climate change. It also strongly influences atmospheric dynamics and the hydrologic cycle through surface evaporation, latent heat transport and diabatic heating, and is, in particular, a source of clouds and precipitation.

Atmospheric water vapour is highly variable, both in space and in time. Therefore, measuring it remains a demanding and challenging task. The Zenith Total Delay (ZTD) estimated from GNSS observations, provided at a temporal resolution of minutes and under all weather conditions, can be converted to Integrated Water Vapour (IWV), if additional meteorological variables are available. Inconsistencies introduced into long-term time series from improved GNSS processing algorithms, instrumental, and environmental changes at GNSS stations make climate trend analyses challenging. Ongoing re-processing efforts using state-of-the-art models aim at providing consistent time series of tropospheric data, using 24+ years of GNSS observations from global and regional networks. GNSS is reaching the “maturity age” of 30 years when climate normal of ZTD/IWV (and horizontal gradients) can be derived. Being not assimilated in numerical weather prediction model reanalyses, GNSS products can also be used as independent datasets to validate climate model outputs (ZTD/IWV). However, what is the actual use of GNSS ZTDs in climate monitoring? What are the advantages of using GNSS ZTDs for climate monitoring? In addition, what would be the best ZTD time series to serve the climate community?

The presentation will provide a review of the progress made in and the status of using GNSS tropospheric datasets for climate research, highlighting the challenges and pitfalls, and outlining the major remaining steps ahead. We will show examples demonstrating the benefits for climate monitoring brought by using GNSS ZTD and/or IWV datasets in complement to other observations.

This contribution is related to the activities of JWG C.2: Quality control methods for climate applications of geodetic tropospheric parameters,, of the IAG Inter-Commission Committee on "Geodesy for Climate Research" (ICCC).

How to cite: Pacione, R., Santos, M., Dick, G., Jones, J., Pottiaux, E., Rinke, A., Van Malderen, R., and Elgered, G.:  Ground-based GNSS for climate research: review and perspectives, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9087,, 2021.