ECMWF, as the Entrusted Entity for the Copernicus Climate Change Service (C3S), invites Tenders for the maintenance and extension of C3S windstorm and storm surge services. The requirements are split into two Lots: maintenance and extension of the Operational Windstorm Service (Lot 1), and maintenance and extension of operational storm surge products (Lot 2). For each Lot, ECMWF intends to award a single Framework Agreement for a period of maximum 28 months, which shall be implemented via a single multi-annual Service Contract expected to commence in Q3 2026. Tenderers are invited to submit their Tenders for either one or both Lots. Note that the expertise required for each Lot strongly differ. In cases where a Tenderer opts to submit Tenders for both Lots, it is mandatory that each Tender is presented as a separate submission, with its own set of documents, including but not limited to, technical proposals, pricing tables and any required supporting documents. Tenderers must ensure that the submissions for each Lot are independently viable and stand on their own merits. At the same time, Tenderers should indicate what synergies, including cost savings, can be achieved should more than one Lot be awarded to them.

C3S2_413_bis Lot 1: Maintenance and extension of the Operational Windstorm Service

The objective of Lot 1 is to ensure the continued operational delivery, maintenance, and scientific robustness of the Operational Windstorm Service and its ERA5-based extra-tropical cyclone (ETC) diagnostics, datasets, applications and notebooks, while extending the service to meet evolving user needs, especially for insurance/catastrophe modelling, by strengthening QA, providing L2 user support and updated training material, and preparing migration to ERA6 through targeted testing and sensitivity assessment. The extension work includes broadening the geographic domain beyond Europe (to at least Northern Hemisphere mid-latitudes, and potentially Southern Hemisphere), adding variables and derived products (e.g., precipitation linkage, return periods), improving downstream-relevant statistics (including UNSEEN/synthetic/analogue/AI generative approaches with benchmarking and documentation), developing storm indicators usable across reanalysis and climate projections (CMIP/CORDEX) without explicit storm tracking, and co-developing user-driven case studies and online demonstrators with clear documentation and dissemination assets in coordination with ECMWF and (where relevant) Lot 2.

C3S2_413_bis Lot 2: Maintenance and extension of operational storm surge products

The objective of Lot 2 is to ensure the continued operational running, consistency, and scientific integrity of C3S storm-surge / extreme sea-level products (reanalysis-based coastal water-level time series and related diagnostics) by implementing an operational update cycle (at least monthly), robust QA/QC, and maintained CDS catalogue interfaces/documentation, while preparing for ERA6 via early end-to-end testing and a documented migration plan. In parallel, the lot aims to maintain and evolve derived indicators (percentiles/return periods with uncertainty treatment), explore AI-based approaches (e.g., emulators, post-processing, downscaling) without compromising operational continuity, and restructure/extend the climate projections component so storm-surge/sea-level indicators are produced consistently from a broad, Atlas-aligned CMIP ensemble set with transparent model-selection rules, reproducible processing, and coherent uncertainty characterisation, complemented by updated training/example workflows, L2 support, and cross-lot coordination to enable joint windstorm–storm-surge compound hazard products for insurance and risk-modelling users.