Modeling the Impacts of Urban Green and Cool Roofs on Surface Climate

Given the rapid urbanization and extremely high temperature under climate change, it is urgent to take adaptation and mitigation strategies for anthropogenically-induced urban heat island effect. In this study, based on the frame of Community Land Model Urban (CLMU), a new roof module including cool roof, green roof as well as an irrigation module for green roof was developed to represent the urban heat mitigation strategies. Results indicate that different strategies could have quite different impacts on near surface and surface temperature. In green roof without irrigation case, the temperature is slightly increased due to the insulation effect. While in both cool roof and green roof with irrigation cases, surface temperature is reduced more significantly than near-surface air temperature. Based on the land surface energy and water balances, we also predict the effects of cool roof without CLM5. On the other hand, as irrigation is important for maintaining the cooling effect for green roof especially under dry condition, we further investigate the amount of water consumption to maintain the cooling effect.