Investigating the Effects of "Cool" Solar Reflective Pavements on California Climate

Implementing "Cool pavement" is a local mitigation strategy that can reduce urban heat islands. We investigated the climate impacts of widespread deployment of cool pavements by increasing the albedo of the pavements from 0.1 to 0.5 to understand the efficiency of cool pavements in reducing the temperature in California's urban areas. A validated parameterization of WRF model coupled with Single Layer Urban Canopy Model (SLUCM) is employed to simulate the effects of pavements at the bottom of canopy on urban heat islands. The results show local surface air temperature reductions, peaking at late morning and late evening which coincides with the lowest boundary layer height in the day time. Summer time temperature reductions up to 0.62 K in the evening (20:00 local) and 0.32 K in afternoon (14:00) in California are predicted. The cooling effects of 15 cities in California are sampled and analyzed. The average temperature reductions for the cities in California show 0.32 K temperature reduction per 0.1 total albedo reduction in the afternoon (14:00) which is consistent with the previous works. The linear relation between temperature reductions and the albedo increase is used to estimate the effect of cool pavements in "No Canopy" state, which can be used as an upper bound of the effects of cool pavements.