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−.

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.

Urban Air Quality Model Inter-Comparison Study (UMICS) for Improvement of PM2.5 Simulation in Greater Tokyo Area of Japan

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.

Numerical Analysis on Biogenic Emission Sources Contributing to Urban Ozone Concentration in Osaka, Japan

Hiroshi Nishimura,Hikari Shimadera,Akira Kondo,Kazuyo Akiyama,Yoshio Inoue 한국대기환경학회 2015 Asian Journal of Atmospheric Environment (AJAE) Vol.9 No.4

This study conducted analyses on biogenic volatile organic compounds (BVOC) emission sources contributing to urban ozone (O3) concentration in Osaka Prefecture, Japan in summer 2010 by using the Weather Research and Forecasting model (WRF) version 3.5.1 and the Community Multiscale Air Quality model (CMAQ) version 5.0.1. This prefecture is characterized by highly urbanized area with small forest area. The contributions of source regions surrounding Osaka were estimated by comparing the baseline case and zero-out cases for BVOC emissions from each source region. The zero-out emission runs showed that the BVOC emissions substantially contributed to urban O3 concentration in Osaka (10.3 ppb: 15.9% of mean daily maximum 1-h O3 concentration) with day-by-day variations of contributing source regions, which were qualitatively explained by backward trajectory analyses. Although O3 concentrations were especially high on 23 July and 2 August 2010, the contribution of BVOC on 23 July (35.4 ppb: 25.6% of daily maximum O3) was much larger than that on 2 August (20.9 ppb: 14.2% of daily maximum O3). To investigate this difference, additional zero-out cases for anthropogenic VOC (AVOC) emissions from Osaka and for VOC emissions on the target days were performed. On 23 July, the urban O3 concentration in Osaka was dominantly increased by the transport from the northwestern region outside Osaka with large contribution of O3 that was produced through BVOC reactions by the day before and was retained over the nocturnal boundary layer. On 2 August, the concentration was dominantly increased by the local photochemical production inside Osaka under weak wind condition with the particularly large contribution of AVOC emitted from Osaka on the day.

Evaluation of Water Retentive Pavement as Mitigation Strategy for Urban Heat Island Using Computational Fluid Dynamics

Aiza Cortes,Hikari Shimadera,Tomohito Matsuo,Akira Kondo 한국대기환경학회 2016 Asian Journal of Atmospheric Environment (AJAE) Vol.10 No.4

Here we evaluated the effect of using water retentive pavement or WRP made from fly ash as material for main street in a real city block. We coupled computational fluid dynamics and pavement transport (CFD-PT) model to examine energy balance in the building canopies and ground surface. Two cases of 24 h unsteady analysis were simulated: case 1 where asphalt was used as the pavement material of all ground surfaces and case 2 where WRP was used as main street material. We aim to (1) predict diurnal variation in air temperature, wind speed, ground surface temperature and water content; and (2) compare ground surface energy fluxes. Using the coupled CFD-PT model it was proven that WRP as pavement material for main street can cause a decrease in ground surface temperature. The most significant decrease occurred at 1200 JST when solar radiation was most intense, surface temperature decreased by 13.8°C. This surface temperature decrease also led to cooling of air temperature at 1.5 m above street surface. During this time, air temperature in case 2 decreased by 0.28°C. As the radiation weakens from 1600 JST to 2000 JST, evaporative cooling had also been minimal. Shadow effect, higher albedo and lower thermal conductivity of WRP also contributed to surface temperature decrease. The cooling of ground surface eventually led to air temperature decrease. The degree of air temperature decrease was proportional to the surface temperature decrease. In terms of energy balance, WRP caused a maximum increase in latent heat flux by up to 255 W/m2 and a decrease in sensible heat flux by up to 465 W/m2.

Evaluation of the Effect of Regional Pollutants and Residual Ozone on Ozone Concentrations in the Morning in the Inland of the Kanto Region

Yusuke Kiriyama,Hikari Shimadera,Syuichi Itahashi,Hiroshi Hayami,Kazuhiko Miura 한국대기환경학회 2015 Asian Journal of Atmospheric Environment (AJAE) Vol.9 No.1

Increasing ozone concentrations are observed overJapan from year to year. One cause of high ozoneconcentration in the Kanto region, which includesareas inland from large coastal cities such as metropolitanTokyo, is the transportation of precursors bysea breezes. However, high ozone concentrationsare also observed in the morning, before sea breezesapproach inland areas. In this point, there would bea possibility of residual ozone existing above thenocturnal boundary layer affects the ozone concentrationin the following morning. In this study, weutilized the Weather Research and Forecasting modeland the Community Multiscale Air Quality model toevaluate the effect of regional precursors and residualozone on ozone concentrations over the inlandKanto region. The results show that precursors emittedfrom non-metropolitan areas affected inlandozone concentrations more than did precursors frommetropolitan areas. Moreover, calculated resultsindicate downward transportation of residual ozone,resulting in increased concentration. The residualozone was also affected by precursors emitted fromnon-metropolitan areas.