Alexandre Couhert (Géosciences Environnement Toulouse – Université de Toulouse (CNES, CNRS, IRD, UT), France , France); Hugues Capdeville (CLS - Service Localisation et Orbitographie, Toulouse, France , France); Adrien Mezerette (CLS - Service Localisation et Orbitographie, Toulouse, France, France); Bock Olivier (Université Paris Cité, Institut de physique du globe de Paris, CNRS, IGN, F-75005 Paris, France & Univ Gustave Eiffel, Géodata Paris, IGN, F-75238 Paris, France, France); Samuel Nahmani (Université Paris Cité, Institut de physique du globe de Paris, CNRS, IGN, F-75005 Paris, France & Univ Gustave Eiffel, Géodata Paris, IGN, F-75238 Paris, France, France); Alvaro Santamaria (Géosciences Environnement Toulouse – Université de Toulouse (CNES, CNRS, IRD, UT), France , France); Stepanek Petr (Research Institute of Geodesy, Topography and Cartography, Czech Republic , Czech Republic); Nagarajan Balasubramanian (IIT Kanpur, India); Onkar Dikshit (IIT Kanpur, India)

We present and evaluate a global 10-year record (2016-2025) of zenith tropospheric delay (ZTD) estimated from DORIS observations with CNES’ GINS software. Because of the long-term continuity of the DORIS network maintained by CNES and IGN, DORIS-derived tropospheric products are a promising source of information for long-duration atmospheric and climate-related studies.
The DORIS-derived ZTD series are evaluated against GNSS-derived ZTD products at co-located IDS/IGS sites, with comparisons performed at matched epochs. We first assess the consistency of the CNES/CLS IDS solutions with the corresponding IGS products and then evaluate both datasets with respect to ERA5. Using these co-locations, we quantify random scatter and systematic offsets, analyze site-by-site time series and global spatial patterns, and examine seasonal to interannual variability. All-time series are interpolated onto a common temporal grid using piecewise-linear interpolation, which proved more robust than cubic-spline interpolation in terms of residual stability.
The analysis also investigates DORIS–GNSS integrated water vapor (IWV) biases and drifts, including relative differences with respect to ERA5. In addition, we perform an independent evaluation of the IDS solutions using 2021–2025 single-satellite tropospheric products from the IGN Analysis Center, including zenith dry delay and corrected wet delay estimates. After homogenization, DORIS-based tropospheric products show encouraging precision and long-term consistency, supporting their potential value for long-term monitoring of atmospheric water vapor.