Eri Saikawa, Postdoctoral Associate, Center for Global Change Science, M.I.T
Harvard China Project Seminar
We evaluate the current and possible future vehicle emissions from China and their impacts on the Asian air quality. We modify the Regional Emission Inventory for Asia (REAS) for China’s road transport sector in 2000 and create two scenarios for 2020 using the updated Chinese data for vehicle numbers, annual mileage and emission factors. For the scenarios in 2020, we include a business-as-usual (same emission factors as in 2000), and a Euro 3 scenario. The Euro 3 scenario represents a case in which all vehicles meet the Euro 3 vehicle emission standards in 2020. This is plausible considering that the national standards for new cars in China were Euro 3 from July, 2007 until China implemented the Euro 4 standards in July, 2010. The inventory includes both gasoline and diesel fuel types for six different categories (motorcycles, passenger cars, light duty vehicles, buses, trucks and rural vehicles). Using the Weather Research Forecast model with chemistry (WRF/Chem), we further examine the regional air quality response to these three scenarios in China in 2000 and 2020. We evaluate the 2000 model results using observations and find a trend of overestimation for ozone in most months, but generally show a relatively good fit with a mean bias of 3.3 ppbv for the four simulated months (January, April, July, and October). In 2020, emissions of CO, NOx, NMVOCs, BC and OC are reduced by 78%, 74%, 63%, 63% and 58%, respectively, under the Euro 3 emission standards relative to the business-as-usual scenario. Regional air quality shows great improvement by effective implementation of the Euro 3 emission standards at the national level in China, compared to no regulations. Reduction of more than 10 ppbv ozone mixing ratio and more than 0.5 µg/m3 of BC surface concentrations are found in northeast China. Depending on the season, neighboring countries also see a reduction of up to 5-6 ppbv reduction in ozone mixing ratio and 0.05 µg/m3 of BC surface concentration. We find that effective regulation of China’s road transport sector will be of significant benefit for air quality within China and more broadly within East Asia as well.