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Numerical Simulation of Extreme Air Pollution by Fine Particulate Matter in China in Winter 2013
Hikari Shimadera,Hiroshi Hayami,Toshimasa Ohara,Yu Morino,Akinori Takami,Satoshi Irei 한국대기환경학회 2014 Asian Journal of Atmospheric Environment (AJAE) Vol.8 No.1
In winter 2013, extreme air pollution by fine particulatematter (PM2.5) in China attracted much publicattention. In order to simulate the PM2.5 pollution,the Community Multiscale Air Quality model drivenby the Weather Research and Forecasting model wasapplied to East Asia in a period from 1 January 2013to 5 February 2013. The model generally reproducedPM2.5 concentration in China with emission data inthe year 2006. Therefore, the extreme PM2.5 pollutionseems to be mainly attributed to meteorological (weakwind and stable) conditions rather than emissionincreases in the past several years. The model wellsimulated temporal and spatial variations in PM2.5concentrations in Japan as well as China, indicatingthat the model well captured characteristics of thePM2.5 pollutions in both areas on the windward andleeward sides in East Asia in the study period. Inaddition, contribution rates of four anthropogenicemission sectors (power generation, industrial, residentialand transportation) in China to PM2.5 concentrationwere estimated by conducting zero-out emissionsensitivity runs. Among the four sectors, the residentialsector had the highest contribution to PM2.5concentration. Therefore, the extreme PM2.5 pollutionmay be also attributed to large emissions from combustionfor heating in cold regions in China.
Analysis of Summertime Atmospheric Transport of Fine Particulate Matter in Northeast Asia
Hikari Shimadera,Hiroshi Hayami,Yu Morino,Toshimasa Ohara,Satoru Chatani,Shuichi Hasegawa,Naoki Kaneyasu 한국기상학회 2013 Asia-Pacific Journal of Atmospheric Sciences Vol.49 No.3
In Northeast Asia, the effect of long-range transport of air pollutants is generally pronounced in spring and winter, but can be important even in summer. This study analyzed summer-time atmospheric transport of elemental carbon (EC) and sulfate (SO42−) with the Community Multiscale Air Quality (CMAQ) model driven by the Weather Research and Forecasting (WRF) model. The WRF/CMAQ modeling system was applied to regions ranging from Northeast Asia to the Greater Tokyo Area in Japan in summer 2007. In terms of EC,while the model simulated well the effect of long-range transport, the simulation results indicated that domestic emissions in Japan dominantly contributed (85%) to EC concentrations in the Greater Tokyo. In terms of SO42−, the simulation results indicated that both domestic emissions (62%) and long-range transport from the other countries (38%) substantially contributed to SO42− concentrations in the Greater Tokyo. Distinctive transport processes of SO42− were associated with typical summer-time meteorological conditions in the study region. When a Pacific high-pressure system covered the main island of Japan, domestic emissions, including volcanic emission, dominantly contributed to SO42− concentrations in the Greater Tokyo. When a high-pressure system prevailed over the East China Sea and lowpressure systems passed north of Japan, synoptic westerly winds associated with this pressure pattern transported a large amount of SO42− from the continent to Japan. In addition, although heavy precipitation and strong wind decreased SO42− concentrations near the center of a typhoon, peripheral typhoon winds occasionally played an important role in long-range transport of SO42−.
Hikari Shimadera,Hiroshi Hayami,Satoru Chatani,Tazuko Morikawa,Yu Morino,Yasuaki Mori,Kazuyo Yamaji,Seiji Nakatsuka,Toshimasa Ohara 한국대기환경학회 2018 Asian Journal of Atmospheric Environment (AJAE) Vol.12 No.2
The urban model inter-comparison study (UMICS) was conducted in order to improve the performance of air quality models (AQMs) for simulating fine particulate matter (PM2.5) in the Greater Tokyo Area of Japan. UMICS consists of three phases: the first phase focusing on elemental carbon (UMICS1), the second phase focusing on sulfate, nitrate and ammonium (UMICS2), and the third phase focusing on organic aerosol (OA) (UMICS 3). In UMICS2/3, all the participating AQMs were the Community Multiscale Air Quality modeling system (CMAQ) with different configurations, and they similarly overestimated PM2.5 nitrate concentration and underestimated PM2.5 OA concentration. Various sensitivity analyses on CMAQ configurations, emissions and boundary concentrations, and meteorological fields were conducted in order to seek pathways for improvement of PM2.5 simulation. The sensitivity analyses revealed that PM2.5 nitrate concentration was highly sensitive to emissions of ammonia (NH3) and dry deposition of nitric acid (HNO3) and NH3, and PM2.5 OA concentration was highly sensitive to emissions of condensable organic compounds (COC). It was found that PM2.5 simulation was substantially improved by using modified monthly profile of NH3 emissions, larger dry deposition velocities of HNO3 and NH3, and additionally estimated COC emissions. Moreover, variability in PM2.5 simulation was estimated from the results of all the sensitivity analyses. The variabilities on CMAQ configurations, chemical inputs (emissions and boundary concentrations), and meteorological fields were 6.1-6.5, 9.7-10.9, and 10.3-12.3%, respectively.