Impacts of future climate change and effects of biogenic emissions on surface ozone and particulate matter concentrations in the United States

摘要

Simulations of present and future average regional ozone and PMconcentrations over the United States were performed to investigate thepotential impacts of global climate change and emissions on regional airquality using CMAQ. Various emissions and climate conditions with differentbiogenic emissions and domain resolutions were implemented to study thesensitivity of future air quality trends from the impacts of changingbiogenic emissions. A comparison of GEOS-Chem and CMAQ was performed toinvestigate the effect of downscaling on the prediction of future airquality trends. For ozone, the impacts of global climate change arerelatively smaller when compared to the impacts of anticipated futureemissions reduction, except for the Northeast area, where increasingbiogenic emissions due to climate change have stronger positive effects(increases) to the regional ozone air quality. The combination effect fromboth climate change and emission reductions leads to approximately a 10 %or 5 ppbv decrease of the maximum daily average eight-hour ozone (MDA8) overthe Eastern United States. For PM, the impacts of global climatechange have shown insignificant effect, where as the impacts of anticipatedfuture emissions reduction account for the majority of overall PMreductions. The annual average 24-h PM of the future-year conditionwas found to be about 40 % lower than the one from the present-yearcondition, of which 60 % of its overall reductions are contributed to bythe decrease of SO and NO particulate matters. Changing thebiogenic emissions model increases the MDA8 ozone by about 5–10 % or3–5 ppbv in the Northeast area. Conversely, it reduces the annual averagePM by 5 % or 1.0 μg m in the Southeast region.