Evaluating Convection-Permitting Simulations for capturing urban climate over main cities in South America

Urban areas influence regional climate dynamics, particularly through pronounced urban-rural contrasts. In South America, cities such as Porto Alegre, Buenos Aires, and Córdoba serve as major economic and population centers. These cities experience well-documented Urban Heat Islands (UHI), altered wind patterns, and humidity contrasts, which are further intensified by climate change. These effects become especially critical during heat waves, posing significant challenges for urban populations under global warming scenarios. To address these complexities, convection-permitting models have emerged as a promising tool for capturing the fine-scale urban footprint on local climates. 

This study focuses on evaluating convection-permitting simulations, developed under the CORDEX FPS-URB-RCC SESA (Southeastern South America), capture urban-rural contrasts in three selected cities: Porto Alegre, Buenos Aires, and Córdoba. A total of five models are analyzed, including UCAN-WRF433, NCAR-WRF433, USP-RegCM471, and ICTP-RegCM5pbl1 and b2, with resolutions of 4 km for all models and 12 km for USP-RegCM471. These models are assessed based on key variables, including minimum and maximum air temperature, surface wind speed, humidity, and precipitation. Additionally, the study evaluates heat wave characteristics to understand the urban response to extreme events.

Results highlight the spatial and temporal variability of urban-rural contrasts, with particular emphasis on seasonal variations and diurnal cycles of temperature, humidity, and wind intensity. The study evaluates the added value of increased spatial resolution provided by convection-permitting models.