Impact of cities on the diurnal precipitation and temperature cycle in a changing climate

The relationship between urban areas and higher temperatures, commonly referred to as the urban heat island effect, is well-established within the scientific community and holds critical relevance for policymakers, given that a significant portion of the global population resides in urban regions. However, much less is understood about how cities may influence precipitation patterns in their vicinity. For instance, temperature changes above urban areas could alter atmospheric stability and potentially trigger convective precipitation.

This study examines the impact of urbanization on the diurnal cycle of both precipitation and temperature using the high-resolution CORDEX FPS-CONV convective-permitting model simulation ensemble over the ALP-3 European domain. The ensemble provides kilometer-scale resolution, offering a robust tool to study the urban climate effect. Analyses of current and future climate scenarios reveal that large cities, such as Paris or Barcellona, can significantly influence the diurnal cycles of both temperature and precipitation and differences are highlighted between costal and continental cities in the Mediterranean region.

The ensemble members exhibit 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 underscores the challenges in precisely quantifying the impact of urbanization on precipitation patterns and highlights the need for more detailed future studies leveraging high-resolution kilometer-scale model ensembles to better understand the complex interplay between urbanization and local climate dynamics.