Meteorological, air-quality, and emission-equivalence impacts of urban heat island control in California

Abstract The goal of this study is to analyze the impacts of urban heat-island control, via increased surface albedo, on regional and urban meteorology, emissions, and ozone air quality over a range of summer conditions in California. The ozone air-quality impacts of heat-island control are then converted into precursor-emission equivalents. Linked atmospheric models used in this effort show that significant cooling of the urban canopy and boundary layers can be achieved, particularly during the daytime, but that warming can also occur. The air-quality improvements are significant where surface albedo is increased. Downwind of modified areas, the air-quality impacts can be positive or negative depending on meteorological conditions affecting the formation, transport, removal, and mixing of ozone and its precursors. Overall, and accounting for both positive and negative impacts of increased urban albedo, the models show beneficial net effects for California. The results do not account for additional benefits such as reduced cooling energy use and associated reductions in emissions from point sources, or the potential negative impacts on heating energy use in winter. These have been addressed elsewhere. This paper is a summary of results from a study and detailed report (Taha, 2013a) that can be accessed at http://www.energy.ca.gov/2013publications/CEC-500-2013-061/CEC-500-2013-061.pdf .