Urbanization Exacerbated Rainfall Over European Suburbs Under a Warming Climate

The impacts of cities and climate warming on extreme rainfall under strong synoptic conditions are not well understood. Here, we carry out the first model-based assessment of urban impacts on extreme flood-producing storms for the European region. We identify contrasting roles of cities and climate warming in determining the space-time variability of the July 14, 2021 storm over western Europe. While climate warming dominates the temporal rainfall variability over the domain, cities further enhance total rainfall over their suburbs by dynamically modifying the intensity and position of moisture convergence. There is a cyclonic structure of flow anomalies around the city induced by urban surface roughness. The rainfall anomaly induced by the interactive impacts of cities and climate warming is 50% larger than by those urban impacts alone. We highlight a need to develop a regional framework by reconciling the emerging urban-rural contrasts in vulnerability and preparedness to hydrometeorological extremes.