Effects of the urban development on the near-surface air temperature and surface energy balance: The case study of Madrid from 1970 to 2020

The aim of the present study is to examine the impact of Madrid's urban growth over the last 50 years (1970–2020). We conduct a modelling study using WRF-ARW with the multilayer urban parameterization BEP-BEM, in which different urban parameters have been incorporated at each point within the model's inner domain according to urban expansion from 1970 to 2020. Two scenarios of important societal interest with different meteorological conditions are selected for this study: a period of intense heatwave during the summer season and a short period of strongly stable atmospheric conditions in winter, both in 2020. The results show that in areas where the urban fraction becomes greater an increase in near-surface air temperature is found for both simulated periods, especially during the night. The urbanization modifies the surface energy balance and turbulent transport in Madrid and its surroundings. It leads to a decrease in latent heat flux due to the high impermeability and reduced vegetation in urban areas. Additionally, the urban areas with a higher density of buildings have a high heat capacity, increasing heat flux storage during the day through solar radiation absorption. This stored energy is released at night, exacerbating the increase in nighttime near-surface air temperature in both periods.