Modeling the impacts of large-scale albedo changes on ozone air quality in the South Coast Air Basin

It is expected that high-albedo materials will be used widely in urban areas particularly in warm and hot climates of the U.S. This will likely happen if high-albedo measures are adopted in building energy codes and urban planning regulations. The changes would mean that portions of urbanized airsheds may become more reflective to solar radiation than they currently are. This paper describes a modeling study that was aimed at analyzing the mesoscale meteorological and ozone air quality impacts of large-scale increases in surface albedo in California's South Coast Air Basin (SoCAB). For a late-August episode, the simulations indicate that implementing high-albedo materials in the SoCAB would have a net effect of reducing ozone concentrations. With extreme increases in albedo, peak concentrations at 3 p.m. decrease by up to 7% (from 220 down to 205 ppb) while the total ozone mass in the mixed layer decreases by up to 640 metric tons (a decrease of 4.7%). Largest reductions in concentrations at 3 p.m. are on the order of 50 ppb whereas the largest increases are on the order of 20 ppb. With respect to the National Ambient Air Quality Standard, domain-wide population-weighted exceedance exposure to ozone decreases by up to 16% during peak afternoon hours and by up to 10% during the day-time. reserved.