The Paris 2024 Olympics Research Demonstration Project

Masson, V., Wurtz, J., De Coning, E., Abeillé, P., Blunn, L., Forster, A., Hanley, K., Kumar, V., Lean, H., Leroyer, S., Ma, X., Montmerle, T., Ruin, I., Sanchez, O., Sartelet, K., Saya, A., Schulz, J.-P., Varnet, G., Antoine, S., Arik, A., Augros, C., Capo, J., Carvalho, A., Christen, A., De Munck, C., Demuth, J., Doeuvre, K., Dumas, G., Franklin, C., Garrouste, O., Golding, B., Goret, M., Graille, E., Grimmond, S. ORCID: https://orcid.org/0000-0002-3166-9415, Haeffelin, M., Halliwell, C., Kawabata, T., Kotthaus, S., Kumar, R., Kuznetsov, K., Lauer, A., Lemonsu, A., Lin, C., Lugon, L., Morrison, W., Nagel, T., Nishi, A., Niyogi, D., Perrels, A., Roberts, G., Rosso, A., Hailey Shin, H., Sützl, B., Suri, D., Ulbrich, S., Singh, M., Strömberg, J., Theeuwes, N., Wei, Y. and Zonato, A. (2026) The Paris 2024 Olympics Research Demonstration Project. Bulletin of the American Meteorological Society. ISSN 1520-0477 doi: 10.1175/BAMS-D-25-0008.1 (In Press)

Abstract/Summary

The Paris 2024 Olympics Research Demonstration Project lasted five years and was endorsed by the World Weather Research Programme within WMO to improve urban weather forecasts, using the metropolitan area of Paris as a case study. Meteorological institutes and universities from ten countries participated. The project had three objectives: to increase knowledge on urban summer meteorological hazards; to improve hectometric-scale numerical weather prediction models in cities; and to facilitate the co-production of weather information for large sporting events. Increased convective activity downwind of Paris was highlighted by a new radar- and lightning-based climatology, and numerical experiments identified its potential driving processes. Collaborative analyzes of past heat waves improved air quality models for the Olympics and simulations of thermal comfort variability. Advances in urban-scale modeling enabled real-time intercomparison of seven hectometric or kilometric scale atmospheric models that provided daily forecasts throughout the Olympics and Paralympics. Hectometric models showed similarities in convective precipitation characteristics, tending to have an excessive number of small showers and grid length dependence. Model intercomparisons also showed variability in Urban Heat Island intensity and unexpected differences in urban heat plume extent. A sociological study highlighted the differences in viewpoints between forecasters and sport managers and the importance of transparency in communicating uncertainties. Finally, a decision-making procedure to manage extreme heat contingencies for the “Marathon for All” Olympics public event was developed based on a 100-m grid-length model in collaboration with the weather forecasters’ team. All these insights open new scientific questions in urban climate research and ways forward for future hectometric numerical weather prediction.