Are Diurnal Precipitation and Temperature Cycle affected by Cities in a Changing Climate?

The Urban Heat Island (UHI) effect, characterized by elevated temperatures in urban areas compared to their rural surroundings, poses significant challenges to human health, energy consumption, and environmental sustainability. But how can cities influence precipitation patterns in their vicinity? Can temperature changes above urban areas alter atmospheric stability and potentially trigger convective precipitation? This study aims to address these questions by examining the impact of urbanization on the diurnal cycle of both precipitation and temperature using the high-resolution CORDEX FPS-CONV convection-permitting model simulation ensemble over the ALP-3 European domain. With its kilometer-scale resolution, the ensemble provides a powerful tool to explore the urban climate effect. Analyses of current and future climate scenarios show that large cities, such as Paris and Barcelona, can significantly impact the diurnal cycles of both temperature and precipitation, with notable differences observed between coastal and continental cities in the Mediterranean region. The ensemble members reveal considerable variability in how urbanization affects precipitation, with discrepancies not only across ensemble members but also among different cities within the same model simulation. This variability highlights the challenges in precisely evaluating the impact of urbanization on precipitation patterns and stresses the need for more detailed future studies leveraging high-resolution kilometer-scale model ensembles to better understand the complex interplay between local climate dynamics and urbanization.