Part of the book: Climate Change
Meteorological and photochemical impacts of increasing urban albedo or reflectance over Madrid city have been simulated using a mesoscale climatic model (WRF) coupled to an air quality modeling system (AEMM/CMAQ). We have evaluated the influence over the concentration of the main pollutants of two different interventions with increasing levels of albedo enhancement over all urban categories: a low albedo or cool roofs scenario (Alb1), where only roof albedo was modified (+0.35), and a high albedo scenario (Alb2), increasing both roof albedo (+0.35) and pavement albedo (+0.15). Simulations were run for two periods of 72 h, representative of summer and winter conditions. In both scenarios, surface air temperatures were cooled, with averaged midday reductions at the urban area of −0.2 (−0.5)°C for winter (summer) for Alb1 and −0.3 (−0.7)°C for winter (summer) for Alb2. Peak summer midday cooling at city center was −1.4°C and −1.6 ºC for Alb1 and Alb2, respectively. Pollutant concentrations were modified, with reductions in O3 levels, higher in summer, and increases in NO2 levels, bigger in winter period. Slight increases were also observed in winter for SO2 and particulate matter (PM2.5 and PM10) in both scenarios.