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Excess inputs of reactive nitrogen (Nr) from the atmosphere will cause disturbances to forest ecosystems, including soil and stream water acidification, plant nutrient imbalances, alterations of sp...

A long-term historical emission inventory of air and climate pollutants in East, Southeast, and South Asia during 1950–2015 was developed as the Regional Emission inventory in ASia version 3 (REASv3). REASv3 provides details of emissions from major anthropogenic sources for each country and its sub-regions and also provides monthly gridded data with 0.25∘ × 0.25∘ resolution. The average total emissions in Asia during 1950–1955 and during 2010–2015 (growth rates in these 60 years estimated from the two averages) are as follows: SO2: 3.2 Tg, 42.4 Tg (13.1); NOx: 1.6 Tg, 47.3 Tg (29.1); CO: 56.1 Tg, 303 Tg (5.4); non-methane volatile organic compounds: 7.0 Tg, 57.8 Tg (8.3); NH3: 8.0 Tg, 31.3 Tg (3.9); CO2: 1.1 Pg, 18.6 Pg (16.5) (CO2 excluding biofuel combustion 0.3 Pg, 16.8 Pg (48.6)); PM10: 5.9 Tg, 30.2 Tg (5.1); PM2.5: 4.6 Tg, 21.3 Tg (4.6); black carbon: 0.69 Tg, 3.2 Tg (4.7); and organic carbon: 2.5 Tg, 6.6 Tg (2.7). Clearly, all the air pollutant emissions in Asia increased significantly during these 6 decades, but situations were different among countries and regions. Due to China's rapid economic growth in recent years, its relative contribution to emissions in Asia has been the largest. However, most pollutant species reached their peaks by 2015, and the growth rates of other species were found to be reduced or almost zero. On the other hand, air pollutant emissions from India showed an almost continuous increasing trend. As a result, the relative ratio of emissions of India to that of Asia has increased recently. The trend observed in Japan was different from the rest of Asia. In Japan, emissions increased rapidly during the 1950s–1970s, which reflected the economic situation of the period; however, most emissions decreased from their peak values, which were approximately 40 years ago, due to the introduction of control measures for air pollution. Similar features were found in the Republic of Korea and Taiwan. In the case of other Asian countries, air pollutant emissions generally showed an increase along with economic growth and motorization. Trends and spatial distribution of air pollutants in Asia are becoming complicated. Data sets of REASv3, including table of emissions by countries and sub-regions for major sectors and fuel types, and monthly gridded data with 0.25∘ × 0.25∘ resolution for major source categories are available through the following URL: https://www.nies.go.jp/REAS/index.html (last access: 31 October 2020).

The total OH reactivity of the secondary products formed from the OH-initiated oxidation of toluene, p-xylene, and 1,3,5-trimethylbenzene was directly measured in the presence of NOx using a laboratory environmental chamber in order to investigate unidentified reactive species in urban air. The total OH reactivity was also calculated from the concentrations of the reactants and products, which were monitored by Fourier-transform infrared spectroscopy. The difference between the measured and calculated OH reactivity, the so-called missing OH reactivity, comprised 58–81% of the total OH reactivity of the secondary products. These results suggest that the secondary products formed from the oxidation of aromatic hydrocarbons may be important candidates in accounting for the missing OH reactivity in the analyses of urban environments. The Master Chemical Mechanism (MCM) calculations were performed to predict the temporal variation in the total OH reactivity for the oxidation of aromatic hydrocarbons. The MCM calculations successfully reproduced the observed total OH reactivity when the particle and semi-volatile product concentrations were negligibly low. The MCM calculations were used to identify the missing secondary products. The results suggest that important components of the missing OH reactivity are unsaturated multifunctional products such as unsaturated dicarbonyls, unsaturated epoxydicarbonyls, and furanones.

We compare nine emission inventories of nitrogen oxides including four satellite-derived NOx inventories and the following bottom-up inventories for East Asia: REAS (Regional Emission inventory in ASia), MEIC (Multi-resolution Emission Inventory for China), CAPSS (Clean Air Policy Support System) and EDGAR (Emissions Database for Global Atmospheric Research). Two of the satellite-derived inventories are estimated by using the DECSO (Daily Emission derived Constrained by Satellite Observations) algorithm, which is based on an extended Kalman filter applied to observations from OMI or from GOME-2. The other two are derived with the EnKF algorithm, which is based on an ensemble Kalman filter applied to observations of multiple species using either the chemical transport model CHASER and MIROC-chem. The temporal behaviour and spatial distribution of the inventories are compared on a national and regional scale. A distinction is also made between urban and rural areas. The intercomparison of all inventories shows good agreement in total NOx emissions over mainland China, especially for trends, with an average bias of about 20 % for yearly emissions. All the inventories show the typical emission reduction of 10 % during the Chinese New Year and a peak in December. Satellite-derived approaches using OMI show a summer peak due to strong emissions from soil and biomass burning in this season. Biases in NOx emissions and uncertainties in temporal variability increase quickly when the spatial scale decreases. The analyses of the differences show the importance of using observations from multiple instruments and a high spatial resolution model for the satellite-derived inventories, while for bottom-up inventories, accurate emission factors and activity information are required. The advantage of the satellite-derived approach is that the emissions are soon available after observation, while the strength of the bottom-up inventories is that they include detailed information of emissions for each source category.

Anthropogenic air pollutant emissions have been increasing rapidly in China, leading to worsening air quality. Modelers use emissions inventories to represent the temporal and spatial distribution of these emissions needed to estimate their impacts on regional and global air quality. However, large uncertainties exist in emissions estimates. Thus, assessing differences in these inventories is essential for the better understanding of air pollution over China. We compare five different emissions inventories estimating emissions of carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), and particulate matter with an aerodynamic diameter of 10 µm or less (PM10) from China. The emissions inventories analyzed in this paper include the Regional Emission inventory in ASia v2.1 (REAS), the Multi-resolution Emission Inventory for China (MEIC), the Emission Database for Global Atmospheric Research v4.2 (EDGAR), the inventory by Yu Zhao (ZHAO), and the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS). We focus on the period between 2000 and 2008, during which Chinese economic activities more than doubled. In addition to national totals, we also analyzed emissions from four source sectors (industry, transport, power, and residential) and within seven regions in China (East, North, Northeast, Central, Southwest, Northwest, and South) and found that large disagreements exist among the five inventories at disaggregated levels. These disagreements lead to differences of 67 µg m−3, 15 ppbv, and 470 ppbv for monthly mean PM10, O3, and CO, respectively, in modeled regional concentrations in China. We also find that all the inventory emissions estimates create a volatile organic compound (VOC)-limited environment and MEIC emissions lead to much lower O3 mixing ratio in East and Central China compared to the simulations using REAS and EDGAR estimates, due to their low VOC emissions. Our results illustrate that a better understanding of Chinese emissions at more disaggregated levels is essential for finding effective mitigation measures for reducing national and regional air pollution in China.

This study compares recent CO, NO, NMVOC, SO, BC and OC anthropogenic emissions from several state-of-the-art top-down estimates to global and regional bottom-up inventories and projections from fi...

Atmospheric nitrogen deposition in China has attracted huge public attention in recently years due to the increasing anthropogenic emission of reactive nitrogen (Nr) and its impacts on the terrestrial and aquatic ecosystems. However, limited long-term and multi-site measurements have restrained the understanding on the mechanism of the Nr deposition as well as the chemical transport model (CTM) improvement. In this study, the performance of the simulated wet and dry deposition for different Nr species, i.e., particulate NO3− and NH4+, gaseous NOx, HNO3 and NH3, have been conducted using the framework of Model Inter-Comparison Study for Asia (MICS-Asia) phase III. Nine Models, including 5 WRF-CAMQ models, 2 self-developed regional models, a global model and a RAMS-CMAQ model, have been selected for the comparison. For wet depositions, observation data from 83 measurement sites of EANET, CREN, CAUDN, NADMN and DEE of China have been collected and normalized to compare with model results. In general, most models showed the consistent spatial and temporal variation of both oxidized N (Nox) and reduced N (Nrd) wet depositions in China with the NME around at 50 %, which is lower than the value of 70 % based on EANET observation over Asia. Both the ratio of wet or dry deposition to the total inorganic N deposition (TIN) and the ratios of TIN to their emissions have shown the consistent results with the NNDMN estimations. The performance of ensemble results (ENM) was further assessed with the measurement from satellite. In different regions of China, the results showed that the simulated Nox wet deposition was overestimated in North East China (NE) but underestimated in south of China (SE+SW), while the Nrd wet deposition was underpredicted in all regions by all models. The deposition of Nox have large uncertainties than the Nrd especially in North China (NC), indicating chemical reaction process is one of the most importance factors that affecting the model performance. Compared to Critical load (CL) value, the Nr deposition in NC, SE and SW reached or exceeded the reported CL value and exerted serious ecological impacts. The control of Nrd in NC and SW and Nox in SE would be effective to mitigate the TIN deposition in these regions. More interestingly, the Nr deposition in Tibet plateau with the high ratio of TIN/emission (~3.0), indicating a significant import from outside should be focused in the future due to its climatical influence to the sensitive ecosystem in whole China.

Horizontal grid resolution has a profound effect on model performances on meteorology and air quality simulations. In contribution to MICS-Asia Phase III, one of whose goals was to identify and reduce model uncertainty in air quality prediction, this study examined the impact of grid resolution on meteorology and air quality over East Asia, focusing on the North China Plain (NCP) region. NASA Unified Weather Research and Forecasting (NU-WRF) model has been applied with the horizontal resolutions at 45-, 15-, and 5-km. The results revealed that, in comparison with ground observations, no single resolution can yield the best model performance for all variables across all stations. From a regional average perspective (i.e., across all monitoring sites), air temperature modeling was not sensitive to the grid resolution but wind and precipitation simulation showed the opposite. NU-WRF with the 5-km grid simulated the best wind speed, while the 45-km grid yielded the most realistic precipitation as compared to the site observations. For air quality simulations, finer resolution generally led to better comparisons with observations for O3, CO, NOx, and PM2.5. However, the improvement of model performance on air quality was not linear with the resolution increase. The accuracy of modeled surface O3 out of the 15-km grid was greatly improved over the one from the 45-km grid. Further increase of grid resolution, however, showed diminished impact on model performance on O3 prediction. In addition, finer resolution grid showed large advantage to better capture the frequency of high pollution occurrences. This was important for assessment of noncompliance of ambient air quality standards, which was key to air quality planning and management. Balancing the findings and resource limitation, a 15-km grid resolution was suggested for future MICS-Asia air quality modeling activity. This investigation also found out large overestimate of ground-level O3 and underestimate of surface NOx and CO, likely due to missing emissions of NOx and CO.

Recent regulatory policies in East Asia reduce ozone precursors, but these changes are spatially and temporally nonuniform. This study investigates variations in the long-term trends of tropospheric NO2, HCHO, and HCHO/NO2 ratios to diagnose ozone sensitivity to changes in NOx and volatile organic compound using the Ozone Monitoring Instrument (OMI). Using an adaptive-degree polynomial filter, we identify extremums of time series of NO2 to determine when and how NO2 change. Due to the regulations in China, trends which were predominantly upward turned downward. The years undergoing these changes primarily happened in 2011 and 2012. OMI column densities, however, suggest that NOx sources in South Korea, the Pearl River Delta (PRD), Taiwan, and Japan have not consistently decreased. Specifically, as Chinese exports of NO2 started subsiding, increasing trends in NO2 columns over several Korean cities, including Seoul, become evident. To quantify the changes in NOx emissions from summertime 2010 to 2014, we conduct a 3D-Var inverse modeling using a regional model with MIX-Asia inventory and estimate NOx emissions (in 2010 and 2014) for the PRD (1.6 and 1.5 Gg/d), the Yangtze River Delta (3.9 and 3.0 Gg/d), north China (15.6 and 14.3 Gg/d), South Korea (1.6 and 1.5 Gg/d), and Japan (2.7 and 2.6 Gg/d). OMI HCHO shows upward trends in East Asia resulting from anthropogenic effects; however, the magnitudes are negative in the PRD, Japan, North Korea, and Taiwan. OMI HCHO/NO2 ratios reveal that while South Korea, Japan, and the south of China have undergone toward more NOx-sensitive regime, areas around the Bohai Sea have become more NOx saturated.

The MIX inventory is developed for the years 2008 and 2010 to support the Model Inter-Comparison Study for Asia (MICS-Asia) and the Task Force on Hemispheric Transport of Air Pollution (TF HTAP) by a mosaic of up-to-date regional emission inventories. Emissions are estimated for all major anthropogenic sources in 29 countries and regions in Asia. We conducted detailed comparisons of different regional emission inventories and incorporated the best available ones for each region into the mosaic inventory at a uniform spatial and temporal resolution. Emissions are aggregated to five anthropogenic sectors: power, industry, residential, transportation, and agriculture. We estimate the total Asian emissions of 10 species in 2010 as follows: 51.3 Tg SO2, 52.1 Tg NOx, 336.6 Tg CO, 67.0 Tg NMVOC (non-methane volatile organic compounds), 28.8 Tg NH3, 31.7 Tg PM10, 22.7 Tg PM2.5, 3.5 Tg BC, 8.3 Tg OC, and 17.3 Pg CO2. Emissions from China and India dominate the emissions of Asia for most of the species. We also estimated Asian emissions in 2006 using the same methodology of MIX. The relative change rates of Asian emissions for the period of 2006–2010 are estimated as follows: −8.1 % for SO2, +19.2 % for NOx, +3.9 % for CO, +15.5 % for NMVOC, +1.7 % for NH3, −3.4 % for PM10, −1.6 % for PM2.5, +5.5 % for BC, +1.8 % for OC, and +19.9 % for CO2. Model-ready speciated NMVOC emissions for SAPRC-99 and CB05 mechanisms were developed following a profile-assignment approach. Monthly gridded emissions at a spatial resolution of 0.25° × 0.25° are developed and can be accessed from http://www.meicmodel.org/dataset-mix.

Long-term ozone (O3) and nitric oxide (NOx) from fourteen state-of-the-art chemical transport models are evaluated and intercompared to ozone observations in East Asia, within the framework of the Model Inter-Comparison Study for ASIA phase III (MICS-ASIA III), designed to evaluate the capabilities and uncertainties of current chemical transport models (CTMs) simulations in Asia and provide multi-model estimates of pollution distributions. These models were run by fourteen independent groups in China, Japan, Korea, United States of America and other countries/regions. Compared with MICS-ASIAII, the evaluation against observations were extended to be one-full year in China and the western Pacific Rim from four months and the western Pacific Rim. Potential causes of the discrepancies between model results and observation have also been investigated by assessing the PBL heights, emission fluxes, dry deposition, O3-NOx relationships and vertical profiles among models in this study. In general, the model skills for O3 varied largely with region and seasons. Most models captured the key pattern of monthly and diurnal surface O3 and its precursors in North China Plain, Yangtze River Delta and western Pacific rim, but failed in Peral River Delta of China. A significant overestimation of surface ozone was found in May–September/October and January–May over North China Plain, western Pacific rim and Peral River Delta of China, respectively. A large intermodel variability of O3 existed in all subregions over East Asia in this study, which was caused by the internal parameterizations of chemistry, dry deposition and vertical mixing of models, even though the native schemes in models are similar. Ensemble average of 13 models on O3 did not always exhibit a superior performance compared to certain individual model, in contrast to its superiority in Europe. This suggested that the spread of ensemble-model values hadn't represented all uncertainties of ozone or most models in MICS-ASIAIII missed key processes. Compared with the previous phase of MICS-ASIA（MICS-ASIAII, this study improved the performance of ozone in March at Japan sites. But it predicted too enhanced surface O3 concentrations at western Japan in July, which has not been found in MICS-ASIAII. Major challenges still remain with regards to recognizing the sources of bias in surface O3 over East Asia in CTMs.

The emissions of NO x and CO 2 in East Asia (Northeast and Southeast Asia) contribute more than 30% of the global total since 2008, and consequently the control of air pollutants and CO 2 alleviating regional air pollution and global climate change is of great concern of not only in this region but also worldwide. In order to arrive at a rational view of the short-lived climate pollutants (SLCPs) co-control approach in East Asia, the effectiveness of the reduction of NO x /NMVOC and CH 4 emissions for the reduction of tropospheric O 3 has been evaluated by individual and simultaneous 50%-reduction of the emissions in Northeast Asia (NEA) using both a global chemical climate model (CHASER/SPRINTARS-MIROC), and a regional chemical transport model (WRF-CMAQ). The simultaneous reduction of NO x /NMVOC and CH 4 emissions was found to reduce the regional concentration of surface O 3 in NEA, and globally averaged net radiative forcing most effectively. Global mean RF and regional air quality change were also evaluated for the climate stabilization scenario (“450-ppm”), and climate stabilization with additional air pollution mitigation strengthened scenario (“450-ppm-cntr”) developed in IIASA with the aid of GAINS model. In the 450 ppm-cntr scenario, emissions of NO x NMVOC, BC and OC were further reduced respectively, for East Asia from the emissions in 450 ppm. The improvement of air quality as well as the mitigation of climate change would grant to the basis of the SLCP co-control approach in East Asia.

The behavior of tropospheric NO2 vertical column density (VCD) over continental Southeast Asia (Cambodia, Laos, Myanmar, Thailand, and Vietnam) was systematically analyzed using observations from the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) and a regional chemical transport model (CTM) during 2003–2008. NO2 VCD over continental Southeast Asia showed a distinctive large peak from winter (December) to early spring (April). The regional CTM was configured with anthropogenic emissions taken from the Regional Emission inventory in Asia (REAS) version 2.1 and biomass burning emissions taken from the Global Fire Emissions Database (GFED) version 3.1. Overall, the model could reproduce the NO2 VCD observed by space-borne sensors. A mismatch between satellite observations and the regional CTM was found only in January over Cambodia. A likely reason for this mismatch was diurnal variation in biomass burning emissions. During the analysis period, the largest biomass burning event was reported from December 2003 to April 2004, and a sensitivity analysis was conducted by omitting the biomass burning emissions in the CTM. It was found that the seasonal variations of NO2 VCD, with the peak during winter to early spring, were caused by biomass burning emissions in all countries in continental Southeast Asia. The contribution of biomass burning emissions to NO2 VCD over continental Southeast Asia was an average of 28% during this period and a maximum of 58% in March 2004.

We compare 9 emission inventories of nitrogen oxides including four satellite-derived NOx inventories and the following bottom-up inventories for East Asia: REAS (Regional Emission inventory in ASia), MEIC (Multi-resolution Emission Inventory for China), CAPSS (Clean Air Policy Support System) and EDGAR (Emissions Database for Global Atmospheric Research). Two of the satellite-derived inventories are estimated by using the DECSO (Daily Emission derived Constrained by Satellite Observations) algorithm, which is based on an extended Kalman filter applied to observations from OMI or from GOME-2. The other two are derived with the EnKF algorithm, which is based on an ensemble Kalman Filter applied to observations of multiple species using either the chemical transport model CHASER and MIROC-chem. The temporal behaviour and spatial distribution of the inventories are compared on a national and regional scale. A distinction is also made between urban and rural areas. The intercomparison of all inventories shows good agreement in total NOx emissions over Mainland China, especially for trends, with an average bias of about 20 % for yearly emissions. All the inventories show the typical emission reduction of 10 % during the Chinese New Year and a peak in December. Satellite-derived approaches using OMI show a summer peak due to strong emissions from soil and biomass burning in this season. Biases in NOx emissions and uncertainties in temporal variability increase quickly when the spatial scale decreases. The analyses of the differences show: the importance of using observations from multiple instruments and a high spatial resolution model for the satellite-derived inventories, while for bottom-up inventories, accurate emission factors and activity information are required. The advantage of the satellite derived approach is that the emissions are soon available after observation, while the strength of the bottom-up inventories is that they include detailed information of emissions for each source category.

This study determined the production-based emissions, the consumption-based emissions, and the consumption-based health impact of primary carbonaceous aerosols (black carbon: BC, organic carbon: OC) in nine countries and regions in Asia (Indonesia, Malaysia, the Philippines, Singapore, Thailand, China, Taiwan, South Korea, and Japan) in 2008. For the production-based emissions, sectoral emissions inventory of BC and OC for the year of 2008 based on the Asian international input–output tables (AIIOT) was compiled including direct emissions from households. Then, a multiregional environmental input–output analysis with the 2008 AIIOT which was originally developed by updating the table of 2000 was applied for calculating the consumption-based emissions for each country and region. For the production-based emissions, China had the highest BC and OC emissions of 4520 Gg-C in total, which accounted for 75% of the total emissions in the nine countries and regions. For consumption-based emissions, China was estimated to have had a total of 4849 Gg-C of BC and OC emissions, which accounted for 77% of the total emissions in the Asia studied. We also quantified how much countries and regions induced emissions in other countries and regions. Furthermore, taking account of the source–receptor relationships of BC and OC among the countries and regions, we converted their consumption-based emissions into the consumption-based health impact of each country and region. China showed the highest consumption-based health impact of BC and OC totaling 111 × 103 premature deaths, followed by Indonesia, Japan, Thailand and South Korea. China accounted for 87% of the sum total of the consumption-based health impacts of the countries/regions, indicating that China's contribution to consumption-based health impact in Asia was greater than its consumption-based emissions. By elucidating the health impacts that each country and region had on other countries and from which country the impacts were received, we demonstrated that the characteristics of the consumption-based health impact varied significantly by country and region. We also determined the difference in the health impacts to other countries and regions due to the domestic final demand of each country and region, and the health impact due to the domestic final demand of that country or region.

Satellite observations of the tropospheric NO2 vertical column density (VCD) are closely correlated to, and thus can be used to estimate, surface NOx emissions. In this study, the NO2 VCD simulated by a regional chemical transport model with emissions data from the updated Regional Emission inventory in ASia (REAS) version 2.1 were validated through comparison with multisatellite observations during the period 2000–2010. Rapid growth in NO2 VCD (~11% year−1) driven by the expansion of anthropogenic NOx emissions was identified above the central eastern China (CEC) region, except for the period during the economic downturn. In contrast, slightly decreasing trends (~2% year−1) were identified above Japan accompanied by a decline in anthropogenic emissions. To systematically compare the modeled NO2 VCD, we estimated sampling bias and the effect of applying the averaging kernel information, with particular focus on the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) data. Using the updated REAS, the modeled NO2 VCD reasonably reproduced annual trends observed by multisatellites, suggesting that the rate of increase of NOx emissions estimated by the updated REAS inventory would be robust. Province-scale revision of emissions above CEC is needed to further refine emission inventories. Based on the close linear relationship between modeled and observed NO2 VCD and anthropogenic NOx emissions, NOx emissions in 2009 and 2010, which were not covered by the updated REAS inventory, were estimated. NOx emissions from anthropogenic sources in China in 2009 and 2010 were determined to be 26.4 and 28.5 Tg year−1, respectively, indicating that NOx emissions increased more than twofold between 2000 and 2010. This increase reflected the strong growth of anthropogenic emissions in China following the rapid recovery from the economic downturn from late 2008 until mid-2009. Our method consists of simple estimations from satellite observations and provides results that are consistent with the most recent inventory of emissions data for China.

In Japan, all 47 prefectures conduct routine air quality monitoring at 1145 stations throughout the country to assess environmental effects. This study aims to provide a better understanding of possible estimations of premature mortality in Japan caused by exposure to monitored and modeled concentrations of tropospheric ozone during the period from January to December, 2005. The spatial distribution and temporal variation of ozone concentrations were modeled using the Models-3 Community Multiscale Air Quality modeling system coupled with the Regional Emission Inventory in Asia (CMAQ/REAS). Premature mortality caused by exposure to ozone was calculated assuming a relative risk (RR) value of 1.003 [95% Confidence Interval (CI): 1.001–1.004] for concentrations above 35 ppb according to the SOMO35 index (annual Sum of daily maximum 8-h Ozone Means Over 35 ppb) recommended by WHO (2008). Based on CMAQ/REAS simulations, the estimated all-cause premature mortality in 2005 is about 13,000 (95% CI: 4320–17,300) cases. This value is 2.5 times greater than the estimated premature mortality based on monitored ozone concentrations, which is 5220 (95% CI: 1740–6960) cases.

We have updated the Regional Emission inventory in ASia (REAS) as version 2.1. REAS 2.1 includes most major air pollutants and greenhouse gases from each year during 2000 and 2008 and following areas of Asia: East, Southeast, South, and Central Asia and the Asian part of Russia. Emissions are estimated for each country and region using updated activity data and parameters. Monthly gridded data with a 0.25° × 0.25° resolution are also provided. Asian emissions for each species in 2008 are as follows (with their growth rate from 2000 to 2008): 56.9 Tg (+34%) for SO2, 53.9 Tg (+54%) for NOx, 359.5 Tg (+34%) for CO, 68.5 Tg (+46%) for non-methane volatile organic compounds, 32.8 Tg (+17%) for NH3, 36.4 Tg (+45%) for PM10, 24.7 Tg (+42%) for PM2.5, 3.03 Tg (+35%) for black carbon, 7.72 Tg (+21%) for organic carbon, 182.2 Tg (+32%) for CH4, 5.80 Tg (+18%) for N2O, and 16.0 Pg (+57%) for CO2. By country, China and India were respectively the largest and second largest contributors to Asian emissions. Both countries also had higher growth rates in emissions than others because of their continuous increases in energy consumption, industrial activities, and infrastructure development. In China, emission mitigation measures have been implemented gradually. Emissions of SO2 in China increased from 2000 to 2006 and then began to decrease as flue-gas desulphurization was installed to large power plants. On the other hand, emissions of air pollutants in total East Asia except for China decreased from 2000 to 2008 owing to lower economic growth rates and more effective emission regulations in Japan, South Korea, and Taiwan. Emissions from other regions generally increased from 2000 to 2008, although their relative shares of total Asian emissions are smaller than those of China and India. Tables of annual emissions by country and region broken down by sub-sector and fuel type, and monthly gridded emission data with a resolution of 0.25° × 0.25° for the major sectors are available from the following URL: http://www.nies.go.jp/REAS/.

We analyzed the source–receptor relationships for particulate polycyclic aromatic hydrocarbon (PAH) concentrations in northeastern Asia using an aerosol chemical transport model. The model successfully simulated the observed concentrations. In Beijing (China) benzo[a]pyren (BaP) concentrations are due to emissions from its own domain. In Noto, Oki and Tsushima (Japan), transboundary transport from northern China (>40°N, 40–60%) and central China (30–40°N, 10–40%) largely influences BaP concentrations from winter to spring, whereas the relative contribution from central China is dominant (90%) in Hedo. In the summer, the contribution from Japanese domestic sources increases (40–80%) at the 4 sites. Contributions from Japan and Russia are additional source of BaP over the northwestern Pacific Ocean in summer. The contribution rates for the concentrations from each domain are different among PAH species depending on their particulate phase oxidation rates. Reaction with O3 on particulate surfaces may be an important component of the PAH oxidation processes.

In this study, the emission inventories of NOx, which is a major air pollutant of South Korea were compared and analyzed. The two bottom-up emission inventories, Clean Air Policy Support System (CAPSS) and Regional Emission inventory in ASia (REAS), which are the latest emission inventories about the air pollutant emissions about South Korea were compared to find out the trend of NOx emission during 1996–2005. Also, these two emission inventories were compared with the top down NOx emissions estimated from satellite observations to validate the amount of NOx emitted from South Korea. The total NOx emission trends, sectoral and regional comparisons were carried out. The trend of the top down estimated NOx emission was similar to CAPSS and REAS. However, the magnitudes of the top down estimated NOx emission were usually closer to those of CAPSS than those of REAS. The NOx emissions from transportation sector of REAS were larger than that of CAPSS, and this corresponded to the difference of total amount of NOx emission between CAPSS and REAS. By comparing the differences of the ratios of the vehicle kilometers traveled (VKT) and emission factors (EFs), it was identified that most of the difference between CAPSS and REAS was due to these factors for diesel vehicles in REAS. Implications of this higher VKT values in REAS were discussed.

The relative contributions of various source regions to the long-term (1980–2005) increasing trend in surface ozone (O3) over Japan were estimated by a series of tracer-tagging simulations using a global chemical transport model. The model well simulated the observed increasing trend of surface O3 including its seasonal variation and geographical features in Japan and demonstrated the relative roles of different source regions in forming this trend. Most of the simulated increasing trend of surface O3 over Japan (~ 97 %) was explained as the sum of trends in contributions of different regions to photochemical O3 production. The increasing trend in O3 produced in China accounted for 36 % of the total increasing trend and those in the other northeast Asian regions (the Korean Peninsula, coastal regions in East Asia, and Japan) each accounted for about 12–15 %. Furthermore, the contributions of O3 created in the entire free troposphere and in West, South, and Southeast Asian regions also increased; and their increasing trends accounted for 16 and 7 % of the total trend, respectively. The impact of interannual variations in climate, in methane concentration, and in emission of O3 precursors from different source regions on the relative contributions of O3 created in each region estimated above was also investigated. The variation of climate and the increase in methane concentration together caused the increase of photochemical O3 production in several regions, and represented about 19 % of the total increasing trend of surface O3 over Japan. The increase in emission of O3 precursors in China caused an increase of photochemical O3 production not only in China itself but also in the other northeast Asian regions and accounted for about 46 % of the total increase in surface O3 over Japan. Similarly, the relative impact of O3 precursor emission changes in the Korean Peninsula and Japan were estimated as about 16 and 4 % of the total increasing trend, respectively. The O3 precursor emission change in regions other than northeast Asia caused increases in surface O3 over Japan mainly through increasing photochemical O3 production in West, South, and Southeast Asia and the free troposphere, and accounted for about 16 % of the total.

Sensitivity maps of atmospheric acid deposition in Japan have not been updated in 20 years. Here, we propose new relative risk maps of surface water acidification in forests based on a weighted overlay of cumulative potential acid deposition (CPAD) simulated for a 25-year period (1981–2005), including the sensitivities of soil and bedrock to acidification. We assumed that relative acidification risk is high in areas that exhibit high sensitivities of soil and bedrock to acid and have received a large amount of cumulative acid deposition over the past several decades. We aggregated fine soil and bedrock maps into a 20-km mesh for overlay onto an 80-km mesh map of CPAD by considering their spatial structures in Japan. Allocation of the weights among CPAD and soil and bedrock sensitivities was performed based on observational trends in river pH over the past 30 years. The resulting risk map for surface water acidification showed that large areas of western Japan, as well as smaller areas of Hokkaido, Tohoku, Kanto, and Kyushu, are at high risk of surface water acidification. Seventy-seven percent of all rivers for which a declining trend in pH was observed from 2001 to 2009 were also high-risk areas. Acid deposition might be one factor controlling surface water acidification in areas with high bedrock sensitivity, in addition to high CPAD and soil sensitivity, although the risk of soil acidification remains unclear.

Greenhouse gas and air pollutant precursor emissions have been increasing rapidly in India. Large uncertainties exist in emissions inventories and quantification of their uncertainties is essential for better understanding of the linkages among emissions and air quality, climate, and health. We use Monte Carlo methods to assess the uncertainties of the existing carbon dioxide (CO2), carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter (PM) emission estimates from four source sectors for India. We also assess differences in the existing emissions estimates within the nine subnational regions. We find large uncertainties, higher than the current estimates for all species other than CO, when all the existing emissions estimates are combined. We further assess the impact of these differences in emissions on air quality using a chemical transport model. More efforts are needed to constrain emissions, especially in the Indo-Gangetic Plain, where not only the emissions differences are high but also the simulated concentrations using different inventories. Our study highlights the importance of constraining SO2, NOx, and NH3 emissions for secondary PM concentrations.

Anthropogenic air pollutant emissions have been increasing rapidly in China. Modelers use emissions inventories to assess temporal and spatial distribution of these emissions to estimate their impacts on regional and global air quality. However, large uncertainties exist in emissions estimates and assessing discrepancies in these inventories is essential for better understanding of the trends in air pollution over China. We compare five different emissions inventories estimating emissions of carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), particulate matter with an aerodynamic diameter of 10 um or less (PM10) from China. The emissions inventories analyzed in this paper include Regional Emissions inventory in ASia v2.1 (REAS); Multi-resolution Emission Inventory for China (MEIC); Emission Database for Global Atmospheric Research v4.2 (EDGAR); the inventory by Yu Zhao (ZHAO); and the Greenhouse Gas and Air Pollution Interactions and Synergies (GAINS). We focus on the period between 2000 and 2008 during which the Chinese economic activities have more than doubled. In addition to the national total, we also analyzed emissions from four source sectors (industry, transportation, power, and residential) and within seven regions in China (East, North, Northeast, Central, Southwest, Northwest, and South) and found that large disagreements (~ seven fold) exist among the five inventories at disaggregated levels. These discrepancies lead to differences of 67 ug/m3, 15 ppbv, and 470 ppbv for monthly mean PM10, O3, and CO, respectively, in modelled regional concentrations in China. We also find that MEIC inventory emissions estimates create a VOC-limited environment that produces much lower O3 mixing ratio in the East and Central China compared to the simulations using REAS and EDGAR estimates. Our results illustrate that a better understanding of Chinese emissions at more disaggregated levels is essential for finding an effective mitigation measure for reducing national and regional air pollution in China.

A new aerosol chemical transport model, the Regional Air Quality Model 2 (RAQM2), was developed to simulate the Asian air quality. We implemented a simple version of a triple-moment modal aerosol dynamics model (MADMS) and achieved a completely dynamic (non-equilibrium) solution of a gas-to-particle mass transfer over a wide range of aerosol diameters from 1 nm to super-μm. To consider a variety of atmospheric aerosol properties, a category approach was utilized in which the aerosols were distributed into four categories: particles in the Aitken mode (ATK), soot-free particles in the accumulation mode (ACM), soot aggregates (AGR), and particles in the coarse mode (COR). The aerosol size distribution in each category is characterized by a single mode. The condensation, evaporation, and Brownian coagulations for each mode were solved dynamically. A regional-scale simulation (Δx = 60 km) was performed for the entire year of 2006 covering the Northeast Asian region. The modeled PM1/bulk ratios of the chemical components were consistent with observations, indicating that the simulated aerosol mixing types were consistent with those in nature. The non–sea-salt SO42− mixed with ATK + ACM was the largest at Hedo in summer, whereas the SOSO42− was substantially mixed with AGR in the cold seasons. Ninety-eight percent of the modeled NO3− was mixed with sea salt at Hedo, whereas 53.7% of the NO3− was mixed with sea salt at Gosan, which is located upwind toward the Asian continent. The condensation of HNO3 onto sea salt particles during transport over the ocean accounts for the difference in the NO3− mixing type at the two sites. Because the aerosol mixing type alters the optical properties and cloud condensation nuclei activity, its accurate prediction and evaluation are indispensable for aerosol-cloud-radiation interaction studies.

We used a chemical transport model to investigate the long-term trends of sulfur deposition in East Asia during 1981–2005. The model reproduced the observed spatial distributions in East Asia of the rate of wet deposition of non-seasalt sulfate (nss-SO42−), volume-weighted mean concentrations of nss-SO42− in precipitation, precipitation, and concentrations in air of gaseous sulfur dioxide and particulate nss-SO42−. The model also reproduced well observed seasonal variations and long-term trends of wet deposition of nss-SO42− in Japan from 1988 to 2005. The increasing rate of wet deposition of nss-SO42− in Japan during 1991–2005 was demonstrated with 99.9% significance for both observed and modeled data. The annual rate of total (wet + dry) sulfur deposition in Japan increased from 15.6 Gmol S y−1 in 1981–1985 to 23.9 Gmol S y−1 in 2001–2005 in response to both increasing contributions from Chinese emissions and the eruption of Miyakejima volcano in 2000. During that 25-year period, approximately 2.1% of the sulfur from Chinese emissions was deposited in Japan. Over the same period, the rate of deposition of sulfur in East Asia increased gradually from 14.2 mmol S m−2 y−1 to 24.0 mmol S m−2 y−1, and the contribution of emissions from China to total sulfur deposition in East Asia increased from 65% to 77%. The contribution of Miyakejima volcano was 3% during 2001–2005. The increase in the sulfur deposition rate was remarkably high on the North China Plain, around Guangzhou, and south of Chongqing. The rate of increase in East Asia was greatest in winter, although the rate of sulfur deposition was highest in summer. Sulfur flux from China to Japan increased by a factor of 2.5 at altitudes of 0–3000 m from 1981 to 2005.

The aim of this study is to assess the premature mortality risks caused by exposure to particulate matter with aerodynamic diameter less than 2.5 μm (PM2.5) and ozone elevated concentrations for the years 2000, 2005, and 2020 in East Asia. The spatial distributions and temporal variations of PM2.5 and ozone concentrations are simulated using the Models-3 Community Multiscale Air Quality Modeling System coupled with the Regional Emission Inventory in Asia. The premature mortality risks caused by exposure to PM2.5 and ozone are calculated based on a relative risk (RR) value of 1.04 (95 % confidence interval (CI): 1.01–1.08) for PM2.5 concentrations above the annual mean limit of 10 μg m−3 taken from the World Health Organization–Air Quality Guideline and based on a RR value of 1.003 (95 % CI: 1.001–1.004) for ozone concentration above 35 ppb of the SOMO35 index (the sum of ozone daily maximum 8-h mean concentrations above 35 ppb). We demonstrate one of the implications of the policy making in the area of environmental atmospheric management in East Asia by highlighting the annual premature mortalities associated with exposure to PM2.5 concentrations that just meet an annual mean concentration of 10 μg m−3, as well as ozone concentrations that have a daily zero SOMO35 index in vulnerable places. Our results point to a growing health risk that may endanger human life in East Asia. We find that the effect of PM2.5 on human health is greater than the effect of ozone for the age group of 30 years and above. We estimate the corresponding premature mortality due to the effects of both ozone and PM2.5 in East Asia for the years 2000 and 2005 to be around 316,000 and 520,000 cases, respectively. For future scenarios of the year 2020, policy succeed case, reference, and policy failed case, the estimated annual premature mortality rates are 451,000, 649,000, and 1,035,000 respectively.

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 m−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 m−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.

We investigated the influence of meteorological variability on the interannual variation of springtime boundary layer ozone over Japan during 1981–2005 by multiyear simulations with the Models-3 Community Multiscale Air Quality (CMAQ) modeling system and the Regional Emission Inventory in Asia (REAS). CMAQ/REAS generally reproduced the observed interannual variability of springtime ozone over Japan, showing year-to-year variations larger than the annual rate of increase of the long-term trend. We then analyzed the influence of the interannual variation of meteorology in simulated results by using the fixed emissions for 2000 and meteorological fields for each year. As a reference parameter, we calculated the area-weighted surface pressure anomaly over the Pacific Ocean east of Japan. When the anomaly has a large negative value, polluted air masses from continental Asia tend to be transported directly to Japan by westerly winds. In contrast, when the anomaly has a large positive value, influence of the outflow from continental Asia tends to be small because the westerly components of wind fields around Japan are comparatively weak. Instead, southerly winds are relatively strong and transport clean air masses from the Pacific Ocean to Japan. Consequently, springtime ozone over Japan is higher (lower) than in ordinary years when the anomaly has a large negative (positive) value. In general, the interannual variation of springtime ozone over Japan is sensitive to the outflow from continental Asia. We also found some correlation between springtime ozone over Japan and the El Niño-Southern Oscillation, indicating that higher and lower springtime ozone over Japan are related to La Niña and El Niño, respectively. Differences in the meridional displacement and diversity of cyclone tracks near Japan between El Niño and La Niña years may be responsible for interannual variations in the springtime boundary layer ozone over Japan.

A four-dimensional variational data assimilation system for optimization of NO x emissions (RC4-NO x ) was developed. A parameterized NO x chemistry scheme was introduced into the RC4-NO x system, and key parameters such as chemical production and loss terms of NO x were calculated in advance using the Community Multiscale Air Quality (CMAQ) modeling system. RC4-NO x was applied to optimize NO x emissions over eastern China (EC) in July 1996, 1999, and 2002 using Global Ozone Monitoring Experiment (GOME) satellite observations of NO 2 vertical column densities (VCDs) and a priori emissions from the Regional Emission Inventory in Asia (REAS). After assimilation, RC4-NO x generally reproduced the spatial distribution, regional averaged values, and time evolution of GOME NO 2 VCDs. Over EC, a priori emissions were reduced by 20% in 1996 and by 8% in 1999, whereas a posteriori emissions were almost the same as a priori emissions in 2002. A priori emissions in the Beijing region were reduced by optimization over the whole simulation period. A posteriori emissions over the Yangtze Delta were larger than a priori emissions in 2002, although they were smaller in both 1996 and 1999. As in other areas, a priori emissions over the North China Plain were reduced in 1996; but those over the eastern part of the plain were increased in 1999, and the area of increased emissions moved slightly westward in 2002. In each region, the growth rates of a posteriori emissions during both 1996–1999 and 1999–2002 became generally larger than those of a priori emissions, and the trends of a posteriori emissions became similar to those of GOME NO 2 VCDs. Our inverse modeling analysis indicates that the rate of increase of NO x emissions over EC from 1996 to 2002 was much larger for a posteriori emissions (49%) than for a priori emissions (19%).

We developed a new emission inventory for Asia (Regional Emission inventory in ASia (REAS) Version 1.1) for the period 1980–2020. REAS is the first inventory to integrate historical, present, and future emissions in Asia on the basis of a consistent methodology. We present here emissions in 2000, historical emissions for 1980–2003, and projected emissions for 2010 and 2020 of SO2, NOx, CO, NMVOC, black carbon (BC), and organic carbon (OC) from fuel combustion and industrial sources. Total energy consumption in Asia more than doubled between 1980 and 2003, causing a rapid growth in Asian emissions, by 28% for BC, 30% for OC, 64% for CO, 108% for NMVOC, 119% for SO2, and 176% for NOx. In particular, Chinese NOx emissions showed a marked increase of 280% over 1980 levels, and growth in emissions since 2000 has been extremely high. These increases in China were mainly caused by increases in coal combustion in the power plants and industrial sectors. NMVOC emissions also rapidly increased because of growth in the use of automobiles, solvents, and paints. By contrast, BC, OC, and CO emissions in China showed decreasing trends from 1996 to 2000 because of a reduction in the use of biofuels and coal in the domestic and industry sectors. However, since 2000, Chinese emissions of these species have begun to increase. Thus, the emissions of air pollutants in Asian countries (especially China) showed large temporal variations from 1980–2003. Future emissions in 2010 and 2020 in Asian countries were projected by emission scenarios and from emissions in 2000. For China, we developed three emission scenarios: PSC (policy success case), REF (reference case), and PFC (policy failure case). In the 2020 REF scenario, Asian total emissions of SO2, NOx, and NMVOC were projected to increase substantially by 22%, 44%, and 99%, respectively, over 2000 levels. The 2020 REF scenario showed a modest increase in CO (12%), a lesser increase in BC (1%), and a slight decrease in OC (−5%) compared with 2000 levels. However, it should be noted that Asian total emissions are strongly influenced by the emission scenarios for China.

We studied trends in Asian air pollution in recent decades using air-quality monitoring station data, satellite retrieval data (GOME NO2), and regional-scale chemical transport model (CTM) simulation. A newly developed annual Asian-scale emission inventory (REAS) from 1980-2003 was used in observation data analysis and CTM. Analyses of recent trends in annual emissions in China by REAS and satellite GOME NO2 show an 8-10% increase after 2000 suggesting the impact of long-range transport of secondary air pollutants in regions and countries downwind. Detailed analyses of O3 observation data in Japan suggest an annual averaged O3 concentration increase of 2% yr-1 due to this long-range transport. We extended our regional air quality study targeting 2020. REAS provides three emission scenarios for China: the reference case (REF), the policy success case (PSC), and the policy failure case (PFC). Projected REF emissions for 2020 show O3 concentrations rising to 75 to 90 ppbv in June and 75 to 85 ppbv in August over the North China Plain. Projected PFC emissions bring an increase of monthly averaged O3 with greater than 20 ppbv (1 ppbv yr-1 growth) in the North China Plain. Surface O3 under the PFC scenario is enhanced by 6 to 8 ppbv over the Korean Peninsula and by 2 to 6 ppbv in Japan from 2000 to 2020 despite the reduction of NOx in Japan. This may become a critical level in air quality in Asia.

In this paper, we compared the costs and benefits of reducing premature mortality caused by exposure to surface ozone and particulate matter with an aerodynamic diameter

There is substantial difference in the coal consumption data in China during 1996–2003 among the three official energy statistics; the province-by-province data in the China Energy Statistics Yearbook (PBP-CESY), the energy balance tables by International Energy Agency (IEA2004) [2004, Energy Statistics of Non-OECD Countries. IEA, Paris], and the country-total data in the China Energy Statistics Yearbook (CT-CESY). Verification of these data was made by GOME satellite observational data for tropospheric NO2 column density in Northern China Plain reported by Irie et al. [2005, Evaluation of long-termtropospheric NO2 data obtained by GOME over East Asia in 1996–2002. Geophysical Research Letter 32(11), L11810, doi: 10.1029/2005GL022770] and Richter et al. [2005, Increase in tropospheric nitrogen dioxide over China observed from space. Nature 437, 129–130]. The NO2 column increase from 1996 to 2002 averaged for the two reports is about 50%, whereas the NOx emission increases based on the PBP-CESY and IEA2004 are 25% and 15%, respectively, and that for CT-CESY is even lower. The discrepancy of the increasing trends between the satellite data and the PBP-CESY emission inventory could be within the uncertainty level with a reservation that the increase in total fuel consumption in PBP-CESY may still be underestimated particularly after the year of 1999. The increasing rates of NOx emissions during 1996–2002 calculated by using the IEA2004 and CT-CESY statistics are apparently underestimated beyond the uncertainty level of the satellite observation, and they are recommended not to be used for emission inventory studies in China during the period.

Ozone (O 3 ) concentrations in East Asia were simulated using the Community Multi-scale Air Quality model and their reproducibility was confirmed by comparing with observation data at Japanese monitoring sites. The model can reproduce the seasonal variation of surface O 3 over Japan. In particular, for the southern parts of Japan, simulated surface O 3 concentrations are strongly correlated with observations. Surface O 3 distribution over East Asia varies dynamically from season to season according to the meteorological condition. In May and June, 2-month average O 3 concentrations in the boundary layer are highest, 55–70 ppbv over East China and Japan at 35–40°N. We estimated the seasonal variation of the contribution of chemically produced O 3 by east Asian regional emissions. In the summertime, the contribution of the regional Asian emissions to O 3 concentrations is around 40–70% over most of China, and the highest is 60–70% ( 3 concentrations over East Asia are strongly influenced by the chemical production by regional emissions during summer season. However, the inflow from outside of this model domain also contributes substantial O 3 concentration over East Asia and its contribution is predominant in winter and early spring. The seasonal change of O 3 concentrations over Japan is characterized by two peaks in spring and autumn and summer minimum. The spring peak event in 2002 consists of split peaks: the first peak in Mar–Apr is mainly influenced by the inflow from outside of this model domain, the second spring peak between May and June is mainly influenced by chemically produced O 3 by regional emissions. During the summer season, O 3 concentrations are the lowest over year because of the weak Asian outflow and northward penetration of the marine air mass.

Low-concentration N2O regions in high latitudes of the lower stratosphere were observed by the Improved Limb Atmospheric Spectrometer (ILAS) for one and half months after the Arctic vortex breakdown in May 1997. A new Chemical Transport Model (CTM), referred to as the CCSR/NIES nudging CTM, has been developed, and used to simulate these low-N2O air masses. The simulation shows that one of the air masses had a horizontal scale of 1,000-1,500 km, and remained at high latitudes for 1.5-2.5 months after the polar vortex breakdown. The simulation also shows that the contrast between the N2O concentration of the low-N2O air mass and that of the ambient air was diminished when the air mass was stretched, which had a considerable influence on the duration of the air mass. From the duration, and the horizontal scale simulated by the CTM, an estimate was made of the horizontal eddy diffusivity after the polar vortex breakdown.

The authors analyze the sensitivities of source regions in East Asia to PM2.5 (particulate matter with an aerodynamic diameter ofor = 2.5 microm) concentration at Fukue Island located in the western part of Japan by using a regional chemical transport model with emission sensitivity simulations for the year 2010. The temporal variations in PM2.5 concentration are generally reproduced, but the absolute concentration is underestimated by the model. Chemical composition of PM2.5 in the model is compared with filter sampling data in spring; simulated sulfate, ammonium, and elemental carbon are consistent with observations, but mass concentration of particulate organic matters is underestimated. The relative contribution from each source region shows the seasonal variation, especially in summer. The contribution from central north China (105 degrees E-124 degrees E, 34 degrees N-42 degrees N) accounts for 50-60% of PM2.5 at Fukue Island except in summer; it significantly decreases in summer (18%). Central south China (105 degrees E-123 degrees E, 26 degrees N-34 degrees N) has the relative contribution of 15-30%. The contribution from the Korean Peninsula is estimated at about 10% except in summer. The domestic contribution accounts for about 7% in spring and autumn and increases to 19% in summer. We also estimate the relative contribution to daily average concentration in high PM2.5 days (35 microg m(-3)). Central north China has a significant contribution of 60-70% except in summer. The relative contribution from central south China is estimated at 46% in summer and about 30% in the other seasons. The contributions from central north and south China on high PM2.5 days are generally larger than those of their seasonal mean contributions. The domestic contribution is smaller than the seasonal mean value in every season; it is less than 10% even in summer. These model results suggest that foreign anthropogenic sources have a substantial impact on attainment of the atmospheric environmental standard of Japan at Fukue Island.The contribution from several source regions in East Asia to PM2.5 concentration at Fukue Island, a remote island located in the western part of Japan and close to the Asian continent, is estimated using a three-dimensional chemical transport model. The model results suggest that PM2.5 that is attributed to foreign anthropogenic sources have a larger contribution than that of domestic pollution and have a substantial impact on attainment of the atmospheric environmental standard of Japan at Fukue Island.

In this study, the top-down NOx emissions estimated from satellite observations of NO2 vertical column densities over North Korea from 1996 to 2009 were analyzed. Also, a bottom-up NOx emission inventory from REAS 1.1 from 1980 to 2005 was analyzed with several statistics. REAS 1.1 was in good agreement with the top-down approach for both trend and amount. The characteristics of NOx emissions in North Korea were quite different from other developed countries including South Korea. In North Korea, emissions from industry sector was the highest followed by transportation sector in the 1980s. However, after 1990, the NOx emissions from other sector, mainly agriculture, became the 2nd highest. Also, no emission centers such as urban areas or industrial areas were distinctively observed. Finally, the monthly NOx emissions were high during the warm season.

In order to evaluate peripheral endothelial function in patients with vasospastic angina (VSA), we measured flow-mediated dilation (FMD) of the brachial artery in patients with VSA and compared it with FMD in patients without VSA. Endothelial dysfunction is considered one of the mechanisms underlying VSA. However, its exact role remains to be clarified. The study included 30 patients with positive spasm-provocational test results without evidence of significant coronary stenosis (VSA group) and 30 patients with negative spasm-provocational test results without evidence of significant coronary stenosis (control group). In each patient, brachial artery diameter responses to hyperemic flow and glyceryl trinitrate spray were measured using high-resolution ultrasound. The carotid intima-media thickness was also measured as a marker of systemic atherosclerosis. FMD was lower in the VSA group (4.8±0.5%) compared with the control group (9.4±0.7%, P < 0.0001). In the VSA group, FMD was not affected by coronary risk factors or the presence of atherosclerotic changes on coronary angiography. Glyceryl trinitrate-induced dilation did not differ between the two groups. The intima-media thickness was comparable between the VSA (0.85±0.04mm) and control groups (0.81±0.05mm). These findings indicated that peripheral endothelial function is impaired only in the VSA group, whereas the atherosclerotic changes were similar in the two groups. We conclude that endothelial dysfunction may be an independent factor responsible for the development of VSA.

It has been reported that flow-mediated dilation (FMD) of the brachial artery and the carotid intima-media thickness (IMT), markers of atherosclerosis, are altered in patients with coronary artery disease (CAD), but it is still not known if the presence of CAD can be detected using these markers. We examined whether the presence of CAD can be detected by FMD of the brachial artery and/or IMT. Eighty-one patients who underwent coronary angiography for the first time were enrolled. In each patient, brachial artery diameter responses to FMD and the administration of nitroglycerin spray, and carotid IMT were measured using high-resolution ultrasound (10 MHz) before coronary angiography. CAD was defined as50% stenosis of a major coronary artery. Fifty-six patients had CAD. FMD was lower and IMT was greater in patients with CAD (FMD, 2.9 +/- 0.2% vs 9.4 +/- 0.5%; IMT, 1.09 +/- 0.05 vs 0.79 +/- 0.04 mm, both p0.0001). Nitroglycerin-induced dilation did not differ in the 2 groups. Multivariate analysis showed that FMD was the only predictor of the presence of CAD (p = 0.0026). Receiver-operating characteristic analysis demonstrated that a cutoff value for FMD for detecting the presence of CAD was 6%, with a sensitivity of 0.93 (52 of 56) and a specificity of 0.88 (22 of 25). These findings suggest that FMD but not IMT may be used to detect the presence of CAD in patients with suspected CAD.