INTERGEO Agenda - english

Atmospheric water vapor is the most significant greenhouse gas and a vital Essential Climate Variable (ECV). This variable plays a key role in monitoring the long-term effects of global climate change. Traditional techniques such as water vapor radiometers and radiosondes measure essential meteorological data. However, over the last two decades Global Navigation Satellite System (GNSS) technology has emerged as a cost-effective tool for continuous atmospheric monitoring in all weather conditions. To exploit this technique for robust climate monitoring, the Global Climate Observing System (GCOS) Reference Upper-Air Network (GRUAN) was established as an international reference observing network. Within this network, GFZ functions as a key processing center, offering a comprehensive source of tropospheric products, including Precipitable Water Vapor (PWV). With over 10 years of consistently processed data now available, the network provides a unique opportunity for long-term climate studies. In this work, 10-year PWV time series across four different climatological regions are investigated. The primary focus is to characterize the long-term stability and traceable uncertainty of the GNSS-derived products. For this purpose, we assess the precision of the estimated GNSS-PWV and validate these products through a comparison with ERA5 reanalysis data. Additionally, the GNSS-PWV time series are analyzed to evaluate the impact of global change on atmospheric moisture distribution.