ECMWF Open Data Transition: monthly download volumes, licence counts, and revenue figures (2014–2025)

This dataset documents the European Centre for Medium-Range Weather Forecasts (ECMWF) transition from the Information Cost licensing model to full open data access under a Creative Commons Attribution 4.0 (CC-BY-4.0) licence, completed in October 2025. It comprises four time series spanning the transition period and the years leading up to it. Contents A single Excel workbook (ecmwf_paper_data.xlsx) with five sheets, and the same data as four standalone CSV files in the csv/ subdirectory. Fig1_Downloads — Monthly ECMWF distribution endpoint download volumes, January 2023 – March 2026 (terabytes per month). Fig2_CloudMirrors — Monthly open data download volumes across all four distribution channels (ECMWF endpoints, AWS Open Data Registry, Google Cloud, Microsoft Azure Planetary Computer), July 2024 – March 2026 (terabytes per month). Fig3_Licences — Year-end count of active ECMWF data licences by category, 2014 – 2025. Fig4_ICRevenue — Annual Information Cost revenue, 2014 – 2025 (millions of euros). Data sources ECMWF distribution endpoints: internal records from the ECMWF Production Data Store (ECPDS) dissemination system. AWS Open Data Registry: AWS access logs, reconciled monthly. Reporting commenced December 2024. Google Cloud: Google Cloud Platform bandwidth egress logs, aggregated monthly. Microsoft Azure: Azure storage account activity logs for the ECMWF container on the Planetary Computer. Licences: ECMWF agreements ledger, year-end snapshots. Information Cost revenue: ECMWF audited annual accounts. Units and conventions Download volumes are reported in terabytes (TB) per month. Revenue figures are reported in millions of euros (€M). Licence counts are integer counts of active agreements at year-end. Notes ECMWF distribution endpoint values for January – August 2024 are linearly interpolated between December 2023 (196 TB) and September 2024 (447 TB); all other values are directly measured. The source column in the Fig1_Downloads sheet flags each row as measured or interpolated. March 2026 cloud-mirror values cover data to 18 March only. Related publication This dataset supports a manuscript on ECMWF's open data transition currently under peer review. The Zenodo record will be updated with the preprint and journal DOI on publication.