Urban areas modify atmospheric processes at scales that can only be represented in detail by km-scale simulations, and even at this scale, their effects need to be parameterized. Such simulations are only available for short periods at very specific sites. The CORDEX Flagship Pilot Study on Urban environments and Regional Climate Change (FPS-URB-RCC) aims to coordinate next- generation km-scale simulations to understand the two-way effect between urban areas and regional climate. In the meantime, the highest resolution resource to explore globally and from a multi-model perspective the effect of climate change on cities is the CORDEX-CORE experiment, which provides Regional Climate Model (RCM) projections with 0.22º grid spacing for most inhabited areas in the world. In this work, we evaluate the representation of cities within CORDEX-CORE. For this purpose, we compare the nocturnal urban heat island against daily observations for a selection of more than 30 cities in different CORDEX domains with varied climates, degrees of continentality, and elevation. At this coarse resolution, cities are represented by few model grid cells, making it challenging to discern urban effects from other regional climate forcings, such as nearby seashores or complex terrain. Moreover, we show that the representation of urban areas within the different models varies widely, adding extra challenges to define reference urban surrounding areas and to systematically compare the results across models.
Fernández et al. (Thu,) studied this question.