Impact of Projected Emission and Climate Changes on Air Quality in the U.S.: from National to State Level

Abstract

Future ambient air quality will respond to changes in anthropogenic and biogenic emissions as well as climate changes, which may vary at national and state levels in different regions of the world. In this work, we applied an advanced online-coupled meteorology and chemistry model, the Weather Research and Forecasting Model with Chemistry (WRF/Chem), to the continental U.S. for current (2001-2010) and future (2046-2055) decades under four climate scenarios including the Representative Concentration Pathways (RCP) 4.5 and 8.5 and the Technology Driver Model (TDM) A1B and B2. Our goal is to quantify the impact of projected changes in anthropogenic and biogenic emissions and climate on future air quality under various climate scenarios for policy analysis for emission control and mitigation of adverse climate change. The simulations are performed at 36-, 12-km, and 4-km over North America, Continental U.S., and selected states, respectively. A comprehensive evaluation has been performed for the current simulation period using available observations from surface networks and satellites and shows an overall good performance in reproducing climatic and chemical observations at all grid scales. Future air quality features greater reduction in PM2.5 by RCP 4.5/8.5 than TDM B2/A1B and decreased O3 over most areas in the U.S. by RCP4.5 and TDM B2, indicating the benefits of carbon policy and technology changes with greater emission reductions. Air quality responds differently to projected changes in anthropogenic emissions in different states and seasons, indicating a need to develop state-specific emission control strategies for different seasons.