Introduction
On 28 October 2025, the Copernicus Climate Change Service (C3S) held the 2nd National Collaboration Programme (NCP) Expert Workshop on Water in Lisbon. The event was hosted by the Portuguese Institute for the Sea and Atmosphere (IPMA) and organised by the European Centre for Medium-Range Weather Forecasts (ECMWF). It brought together 41 participants from 20 countries, including national meteorological and hydrological services, research institutions, C3S NCP representatives, ECMWF staff and contractors.
The Workshop
This workshop followed the 1st C3S NCP Expert Workshop on Water held online in July 2025, which introduced the C3S Water Service and collected initial user input. The first workshop highlighted priorities such as access to transboundary datasets, practical case studies, guidance on seasonal forecast skill, and the need for clearer pathways for training and data access. Building on this foundation, the second workshop focused on technical progress, national use cases and ways to align the developing service with national requirements.
C3S Water Service Development
Participants received an update on the service and its three main components: hydrological monitoring, seasonal hydrological forecasts and long-term hydrological projections. Speakers described progress on modelling workflows, bias-adjusted datasets and the integration of data into the Climate Data Store. They also presented forthcoming web applications that will support users in exploring datasets, assessing model performance and visualising uncertainty. Ongoing engagement activities, including interviews, surveys and a future group of early testers, continue to inform indicator selection and usability features.
National Use Cases
National representatives from Portugal, Ireland, Germany and Italy presented examples of how hydrological data, forecasts and climate projections are applied in their countries. These presentations covered areas such as climate resilient water infrastructure, national flood forecasting systems, downscaled climate projections and the integration of Copernicus data into national water management frameworks.
Discussions and Next Steps
Discussions addressed data resolution, calibration and validation, and the balance between access to raw and bias-adjusted datasets. Participants also emphasised the importance of clear metadata, well-documented workflows and tools that are suitable for users with different levels of expertise. Additional topics included the integration of national data sources, transboundary water challenges and the current limitations in representing small islands in standard hydrological networks.
Conclusion
The workshop concluded with an overview of the next steps. These include a follow-up survey, continued bilateral exchanges through the NCP network and further demonstrations of the C3S Water Service as development progresses. Upcoming activities will focus on refining indicators, expanding validation and preparing early applications for user testing.