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Saikawa E.,Princeton University | Saikawa E.,Massachusetts Institute of Technology | Kurokawa J.,Japan National Institute of Environmental Studies | Kurokawa J.,Japan Environmental Sanitation Center | And 5 more authors.
Atmospheric Chemistry and Physics | Year: 2011

The number of vehicles in China has been increasing rapidly. We evaluate the impact of current and possible future vehicle emissions from China on Asian air quality. We modify the Regional Emission Inventory in Asia (REAS) for China's road transport sector in 2000 using updated Chinese data for the number of vehicles, annual mileage, and emission factors. We develop two scenarios for 2020: a scenario where emission factors remain the same as they were in 2000 (No-Policy, NoPol), and a scenario where Euro 3 vehicle emission standards are applied to all vehicles (except motorcycles and rural vehicles). The Euro 3 scenario is an approximation of what may be the case in 2020 as, starting in 2008, all new vehicles in China (except motorcycles) were required to meet the Euro 3 emission standards. Using the Weather Research and Forecasting model coupled with Chemistry (WRF/Chem), we examine the regional air quality response to China's vehicle emissions in 2000 and in 2020 for the NoPol and Euro 3 scenarios. We evaluate the 2000 model results with observations in Japan, China, Korea, and Russia. Under NoPol in 2020, emissions of carbon monoxide (CO), nitrogen oxides (NOx), non-methane volatile organic compounds (NMVOCs), black carbon (BC), and organic carbon (OC) from China's vehicles more than double compared to the 2000 baseline. If all vehicles meet the Euro 3 regulations in 2020, however, these emissions are reduced by more than 50% relative to NoPol. The implementation of stringent vehicle emission standards leads to a large, simultaneous reduction of the surface ozone (O3) mixing ratios and particulate matter (PM2.5) concentrations. In the Euro 3 scenario, surface O3 is reduced by more than 10 ppbv and surface PM2.5 is reduced by more than 10 μg- 3 relative to NoPol in Northeast China in all seasons. In spring, surface O3 mixing ratios and PM2.5 concentrations in neighboring countries are also reduced by more than 3 ppbv and 1 μg- 3, respectively. We find that effective regulation of China's road transport sector will be of significant benefit for air quality both within China and across East Asia as well. © 2011 Author(s). Source

Horiguchi M.,Kyoto University | Hayashi T.,Kyoto University | Hashiguchi H.,Kyoto University | Ito Y.,Sonic Corporation | Ueda H.,Japan Environmental Sanitation Center
Boundary-Layer Meteorology | Year: 2010

Turbulence structures of high Reynolds number flow in the near-neutral atmospheric boundary layer (ABL) are investigated based on observations at Shionomisaki and Shigaraki, Japan. A Doppler sodar measured the vertical profiles of winds in the ABL. Using the integral wavelet transform for the time series of surface wind data, the pattern of a descending high-speed structure with large vertical extent (from the surface to more than 200-m level) is depicted from the Doppler sodar data. Essentially this structure is a specific type of coherent structure that has been previously shown in experiments on turbulent boundary-layer flows. Large-scale high-speed structures in the ABL are extracted using a long time scale (240 s) for the wavelet transform. The non-dimensional interval of time between structures is evaluated as 3.0-6.2 in most cases. These structures make a large contribution to downward momentum transfer in the surface layer. Quadrant analyses of the turbulent motion measured by the sonic anemometer (20-m height) suggest that the sweep motion (high-speed downward motion) plays a substantial role in the downward momentum transfer. In general, the contribution of sweep motions to the momentum flux is nearly equal to that of ejection motions (low-speed upward motions). This contribution of sweep motions is related to the large-scale high-speed structures. © 2010 Springer Science+Business Media B.V. Source

Morino Y.,Japan National Institute of Environmental Studies | Takahashi K.,Japan Environmental Sanitation Center | Fushimi A.,Japan National Institute of Environmental Studies | Tanabe K.,Japan National Institute of Environmental Studies | And 6 more authors.
Environmental Science and Technology | Year: 2010

Diurnal variations of fossil secondary organic carbon (SOC) and nonfossil SOC were determined for the first time using a combination of several carbonaceous aerosol measurement techniques, including radiocarbon ( 14C) determinations by accelerator mass spectrometry, and a receptor model (chemical mass balance, CMB) at a site downwind of Tokyo during the summer of 2007. Fossil SOC showed distinct diurnal variation with a maximum during daytime, whereas diurnal variation of nonfossil SOC was relatively small. This behavior was reproduced by a chemical transport model (CTM). However, the CTM underestimated the concentration of anthropogenic secondary organic aerosol (ASOA) by a factor of 4-7, suggesting that ASOA enhancement during daytime is not explained by production from volatile organic compounds that are traditionally considered major ASOA precursors. This result suggests that unidentified semivolatile organic compounds or multiphase chemistry may contribute largely to ASOA production. As our knowledge of production pathways of secondary organic aerosol (SOA) is still limited, diurnal variations of fossil and nonfossil SOC in our estimate give an important experimental constraint for future development of SOA models. © 2010 American Chemical Society. Source

Fushimi A.,Japan National Institute of Environmental Studies | Saitoh K.,Japan National Institute of Environmental Studies | Saitoh K.,Akita | Saitoh K.,Eco Analysis Corporation | And 6 more authors.
Atmospheric Environment | Year: 2011

The size distribution of particle number concentrations and comprehensive chemical composition (elemental and organic carbon, elements, ions, and organic compounds) by particle size (diameter: 0.010-10 μm) were measured under no-load and transient conditions in the exhaust from an 8-L diesel engine with no exhaust after-treatment system and from a 3-L diesel vehicle equipped with an oxidation catalyst. High concentrations of nuclei-mode particles were emitted from the 8-L engine under no-load condition (8L-NoLoad), even when low-sulfur (8 ppm) fuel was used, but no nuclei-mode particles were emitted from the 3-L vehicle. Organic carbon accounted for a major part (79-80%) of the measured components of the nanoparticles (diameter: 10-32 nm) under 8L-NoLoad, but elemental carbon accounted for only 8-15%; elements and ions including sulfate accounted for only small percentages. The mass chromatogram (m/. z 85) patterns obtained by gas chromatography-mass spectrometry of the nanoparticles were similar to those for lubricating oil, and the peak profiles for hopanes were equivalent to those in oil. The 17α(H),21β(H)-hopane concentrations per particle mass were higher in smaller particles. The elements concentrated in oil were also concentrated in the nanoparticles. These results suggest that not sulfate and fuel but organics derived from oil were the primary components of the nanoparticles under 8L-NoLoad. From the 17α(H),21β(H)-hopane concentrations, the oil contribution to the sum of measured components in the nanoparticles under 8L-NoLoad was estimated at 79-92%. Comparable oil contributions were estimated from Ca and Zn concentrations. © 2011 Elsevier Ltd. Source

Nishikawa M.,Japan National Institute of Environmental Studies | Matsui I.,Japan National Institute of Environmental Studies | Batdorj D.,National Agency for Meteorology and Environment Monitoring | Jugder D.,National Agency for Meteorology and Environment Monitoring | And 6 more authors.
Atmospheric Environment | Year: 2011

Atmospheric pollution caused by airborne particulate matter in the winter season in Ulaanbaatar, Mongolia is a very serious problem. However, there is a complete lack of scientific observation data to define the situation prior to any remediation. PM10 and PM2.5 average monthly values obtained by continuous monitoring showed the concentrations of particles of both size categories exceeded 100 μg m-3 during November to February (winter). PM10 particles were sampled with filters in January (i.e. during the heating period) and June (i.e.non-heating period) of 2008 in central Ulaanbaatar. To determine the composition of urban airborne particulate matter we analyzed a range of ionic components, multiple elements including heavy metals, and organic and inorganic carbon (soot). We also measured the stable carbon isotope ratio of the soot. Total carbon (sum of organic carbon and inorganic carbon) accounted for 47% of the mass of the PM10 during the heating period and 33% during the non-heating period, and was the largest component of urban airborne particulate matter in Ulaanbaatar. Stable isotope ratios (δ13C) of soot generated during the heating period (-23.4 ± 0.2‰) approximated the ratios for coal used in Ulaanbaatar (-21.3 to -24.4‰), while the ratios during the non-heating period (-27.1 ± 0.4‰) were clearly different from the coal values. In the heating period, a very high correlation was observed between soot and organic carbon, SO4 2-, NO3 -, F-, Zn, As, and Pb, and we concluded that they were derived from coal combustion along with soot. In addition, the concentrations and their ratios relative to each other of Al, Fe, Ca, K, Na, Mg, and Mn hardly differed between the heating period and the non-heating period, and it was concluded that they were derived from soil dust. © 2011 Elsevier Ltd. Source

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