Evaluation of the Urban Heat Island of 12 cities of France in a high-resolution regional climate model simulation

Abstract

The evolution with climate change of local urban climate could exacerbate the environmental and health issues for populations. The CNRM-AROME Convection-Permitting Regional Climate Model (CP-RCM) was coupled to the Town Energy Balance (TEB) urban canopy model at 2.5-km of horizontal resolution to explicitly account for the physical urban-climate processes in interaction with the regional climate conditions. A hindcast simulation over 2000-2018 was analyzed to investigate the potential of this new high-resolution configuration for urban-oriented studies. The simulated urban climate of twelve French cities located in contrasted geographic and climatic contexts was evaluated against observations on a climatological basis. The study of the local atmospheric conditions for each city shows that CNRM-AROME systematically overestimates the incoming solar radiation and precipitation (except in summer), explaining partially the warm(cold) biases in minimum(maximum) daily temperatures. Nevertheless, CNRM-AROME reproduces the UHIN seasonal variability and intensity over most cities, and the regional disparities related to the climatic zones to which the cities belong. The urban climate of coastal cities remains challenging to simulate due to complex local forcings and excessive warm and dry conditions simulated in summer. Overall, the coupling of CNRM-AROME with TEB stands as a relevant tool for studying city-scale weather conditions.