Potential impacts of an Emission Control Area on air quality in Alaska coastal regions

The Alaska-adapted WRF/Chem was used to examine the benefits of the proposed North American Emission Control Area (ECA) for air quality along the Alaska coasts. Simulations were performed alternatively assuming the emissions of 2000, and the emissions of 2000 reduced by the proposed ECA-reductions. In response to the emission reductions, reductions in sulfur (nitrogen) compounds reached up to 9 km (2 km) height. Reductions of sulfate- and nitrate-in-clouds were highest at the top of the atmospheric boundary layer. The strongest reductions occurred over the ECA and the international sea-lanes for sulfur- and nitrogen-compounds, respectively. Along the Gulf of Alaska, sulfur- and nitrogen-compound concentrations decreased significantly in response to the reduced ship-emissions. They decreased over Alaska despite of unchanged emissions in Alaska. PM2.5-speciation only marginally changed in response to the reduced ship-emissions.