The present study investigates the interaction of the 2006 heat wave in North America with two urban environments (Phoenix and New York City) in current climate and future climate simulations. The future climate conditions were generated using the PGW methodology. Multiple high-resolution (3 km) simulations for each of the metropolitan areas were performed using the Weather Research and Forecasting model (WRF) coupled with the single layer urban canopy model, which improves representation of urban processes and explore how irrigated green roofs and cool roofs can mitigate heat wave amplification by UHIs.
To quantify heat wave intensity, an analytical model is applied to the WRF model output that considers the urban surface heat and water vapor exchanges with the atmosphere. A future, warmer climate is found to amplify the heat wave intensity in both Phoenix (21%) and New York City (48%). This amplification can be almost completely offset by adopting irrigated green roofs in urban areas, and partially offset by adopting cool roofs. These results show that a synergistic interaction exists between the urban heat island and a warming climate, and that the additional warming can be (partially) mitigated by appropriate urban planning.