Pacione, Rosa ; Pottiaux, Eric

Invited talk presented at GGOS Topical Meeting on the Atmosphere, Potsdam, Germany on 2024-10-08

Abstract: Geodesy contributes to atmospheric science by providing water vapor, one of the essential climate variables of the Global Climate Observing System. 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 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 into Integrated Water Vapour (IWV) if additional meteorological variables are available. The same parameter, even though not continuously, can be derived from the analysis of data collected at the geodetic VLBI radio telescope. GNSS and VLBI observations are reaching the “maturity age” of 30 years when climate normal of ZTD/IWV (and horizontal gradients) can be derived. For doing this, the complete data set of the observations has to be reprocessed using state-of-the-art models thus providing a consistent time series of tropospheric data, free from inconsistencies introduced by improved data processing algorithms and models. However, instrumental and environmental changes at GNSS stations have to be accounted for before making climate trend analyses. If not assimilated in numerical weather prediction model reanalyses, geodetic products can also be used as independent datasets to validate climate model outputs (ZTD/IWV). The following questions arise: what is the actual use of geodetic tropospheric parameters in climate monitoring? What are the advantages of using them 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 geodetic tropospheric datasets for climate research, highlighting the challenges and pitfalls. Examples demonstrating the benefits for climate monitoring brought by using GNSS ZTD and/or IWV datasets in complement to other observations will be shown.

Keyword(s): GNSS ; VLBI ; Geodesy ; Climate ; Water Vapour ; Troposphere
Links: link