Numerical Analysis of the Behavior of Photochemical Products in Local Flows Over Central Japan in Summer Season-Sensitivity of Ozone Concentration to Emission Sources Over Coastal Urban Areas (original) (raw)
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The transport and formation of photochemical oxidants in central Japan
Atmospheric Environment ( …, 1989
A~ct-Major aspects of the physical and chemical transfo~ations of the oxidant-polIut~ air mass resulting from high precursor emission fluxes of NO, and reactive hydrocarbons (HCs) in the Tokyo metropolitan area and their subsequent long-range transport (LRT) within the Kanto Plain and Nagano Prefecture regions of Japan are evaluated through field observations and model analysis. The field study was conducted in the Kanto District and the Nagano Prefecture in Japan in July 1983. The LRT mechanism in this region is found to involve land/sea breeze, mountain/valley winds, steady onshore winds, strong thermal low and subsidence inversions under a synoptic-scale high pressure. Detailed diagnostic analysis of the LRT event observed on 27 and 28 July 1983 is presented. The analysis is performed using a detailed Eulerian tr~s~~/che~stry model (i.e. the STEM-II model). Ozone profiles in the Tokyo metropolitan area show typical diurnal variation with maximum concentrations of n* 60 ppb in the early afternoon. Beginning about noon local time an extended sea breeze circulation develops and transports this NO, and HC polluted air mass inland. Ozone concentrations in excess of 160 ppb occur in this air mass as it is transported into the inland mountainous regions (located N 150 km downwind of Tokyo) in the early evening.
Atmospheric Environment, 2010
Tropospheric ozone adversely affects human health and vegetation, and biogenic volatile organic compound (BVOC) emission has potential to influence ozone concentration in summer season. In this research, the standard emissions of isoprene and monoterpene from the vegetation of the Kinki region of Japan, estimated from growth chamber experiments, were converted into hourly emissions for July 2002 using the temperature and light intensity data obtained from results of MM5 meteorological model. To investigate the effect of BVOC emissions on ozone production, two ozone simulations for one-month period of July 2002 were carried out. In one simulation, hourly BVOC emissions were included (BIO), while in the other one, BVOC emissions were not considered (NOBIO). The quantitative analyses of the ozone results clearly indicate that the use of spatio-temporally varying BVOC emission improves the prediction of ozone concentration. The hourly differences of monthly-averaged ozone concentrations between BIO and NOBIO had the maximum value of 6 ppb at 1400 JST. The explicit difference appeared in urban area, though the place where the maximum difference occurred changed with time. Overall, BVOC emissions from the forest vegetation strongly affected the ozone generation in the urban area.
Atmospheric Environment, 2010
A photochemical trajectory model (PTM), coupled with the Master Chemical Mechanism (MCM) describing the degradation of 139 volatile organic compounds (VOCs) in the troposphere, was developed and used for the first time to simulate the formation of photochemical pollutants at Wangqingsha (WQS), Guangzhou during photochemical pollution episodes between 12 and 17 November, 2007. The simulated diurnal variations and mixing ratios of ozone were in good agreement with observed data (R 2 ¼ 0.80, P < 0.05), indicating that the photochemical trajectory model e an integration of boundary layer trajectories, precursor emissions and chemical processing e provides a reasonable description of ozone formation in the Pearl River Delta (PRD) region. Calculated photochemical ozone creation potential (POCP) indices for the region indicated that alkanes and oxygenated organic compounds had relatively low reactivity, while alkenes and aromatics presented high reactivity, as seen in other airsheds in Europe. Analysis of the emission inventory found that the sum of 60 of the 139 VOC species accounted for 92% of the total POCP-weighted emission. The 60 VOC species include C 2 eC 6 alkenes, C 6 eC 8 aromatics, biogenic VOCs, and so on. The results indicated that regional scale ozone formation in the PRD region can be mainly attributed to a relatively small number of VOC species, namely isoprene, ethene, m-xylene, and toluene, etc. A further investigation of the relative contribution of the main emission source categories to ozone formation suggested that mobile sources were the largest contributor to regional O 3 formation (40%), followed by biogenic sources (29%), VOC product-related sources (23%), industry (6%), biomass burning (1%), and power plants (1%). The findings obtained in this study would advance our knowledge of air quality in the PRD region, and provide useful information to local government on effective control of photochemical smog in the region.
Journal of Geophysical Research: Atmospheres, 1999
Surface 0 3 and CO measurements were carried out at Oki, Japan during March 1994 to February 1996 in order to elucidate the processes determining temporal variations of 03 and CO in the northeast Asian Pacific rim region. The isentropic trajectory analysis was applied to sort out the influences of the air mass exchange under the Asian monsoon system and the regional-scale photochemical buildup of 03. The trajectories were categorized into five groups which cover background and regionally polluted air masses. The seasonal cycles of 03 and CO in the background continental air mass revealed spring maximum-summer minimum with averaged concentrations ranging from 32 and 120 ppb to 45 and 208 ppb, respectively. In contrast, 03 concentrations in the regionally polluted continental air mass ranged from 44 to 57 ppb and showed a winter minimum and a spring-summer-autumn broad maximum, which was characterized by photochemical 03 production due to anthropogenic activities in northeast Asia. CO concentrations in the same air mass showed a spring maximum of 271 ppb and a summer-autumn minimum of 180 ppb. The photochemical buildup of 03 resulting from anthropogenic activities in this region was estimated to be 21 ppb in summer, while its production was insignificant, an average 3 ppb, in winter. A comparison between data in northeast Asia and in Europe shows many similarities, supporting the contention that photochemical buildup of 03 from large-scale precursor emissions in both regions is very significant. trajectory calculations to observational data in Europe, the Atlantic islands, and North America [Oltmans and Levy, 1992; Derwent et al., 1994; Moody et al., 1995; Harris and Oltmans, underlying mechanism, two different approaches are essentially important. One is trend analysis based on long-term data either 1997; Sirnrnonds et al., 1997]. Northeast Asia is one of the most anthropogenically active aron surface measurements or by sounding routines. Another is the eas in the world and provides an interesting study field for tropoclimatological study of ozone and its precursors which clarifies the mechanism of long-range transport and transformation. Trend spheric ozone buildup. A trend of increasing tropospheric ozone has been observed in this region based on ozone sounding data in analysis has established that surface ozone concentration has increased at least by a factor of 2 or more in many areas of Europe Japan [Akirnoto et al., 1994]. In contrast to Europe, the trend of over this century [Logan, 1985; Bojkov, 1986; Volz and Kley, increasing boundary layer ozone is still continuing in the 1990s in this area, possibly due to a trend of increasing emissions of 1988;
Atmosphere, 2012
The fully coupled WRF/Chem (Weather Research and Forecasting/Chemistry) model is used to simulate air quality over coastal areas of the Sea of Japan. The anthropogenic surface emissions database used as input for this model was based primarily on global hourly emissions data (dust, sea salt, and biomass burning), RETRO (REanalysis of the TROpospheric chemical composition), GEIA (Global Emissions Inventory Activity), and POET (Precursors of Ozone and their Effects in the Troposphere). Climatologic concentrations of particulate matter derived from the Regional Acid Deposition Model (RADM2), chemical mechanism, and the Secondary Organic Aerosol Model (MADE/ SORGAM) with aqueous reactions were used to deduce the corresponding aerosol fluxes for input to the WRF/Chem model. The model was first integrated continuously over 48 hours, starting from 00:00 UTC on 14 March 2008, to evaluate ozone concentrations and other precursor pollutants. WPS meteorological data were used for the WRF/Chem model simulation in this study. Despite the low resolution of global emissions and the weak density of the local point emissions, it was found that the WRF/Chem model simulates the diurnal variation of the chemical species concentrations over the coastal areas of the Sea of Japan quite well. The Air Quality Management Division of the Ministry of the Environment in Japan selected the maximum level of the air quality standard for ozone, which is 60 ppb. In this study, the atmospheric concentrations of ozone over the coastal area of the Sea of Japan were calculated to be 30-55 ppb during the simulation period, which was lower than the Japanese air quality standard for ozone.
Journal of the Meteorological Society of Japan, 2008
In this paper an attempt has been made to elucidate the relationship between the formation of photochemical oxidants and the emission rate of the primary pollutants such as nitrogen oxides (NO X) and reactive hydrocarbons (RH) over the Osaka Bay and its surrounding areas of Japan, by using a three-dimensional grid model. In Harima area, reduction in the primary pollutant emission led to simple decrease in the peak O 3 concentration, and OH and HO 2 radical concentrations. In Osaka area, unlike the Harima area, reduction in NO X emission led to an increase in OH and HO 2 radicals concentrations, and conversely to an increase in O 3 concentration. It has also been found that the time of peak O 3 concentration would appear earlier with reduction in NO X emission, and later with reduction in RH emission. Under meteorological calm condition, the variations of the time of appearance of peak O 3 due to the emissions reduction scenario are small. Sea breeze may be one of the important meteorological phenomena responsible for the transport of pollutants such as NO X , RH, and also O 3 in the polluted coastal areas. These important results suggest that a method for a well-balanced reduction in both NO X and RH emissions is essential for the improvement of air quality from photochemical pollution over the Osaka Bay and its surrounding areas of Japan.
Atmospheric Environment Part a General Topics, 1992
Al~tract-Long-range transport (LRT) of photochemical air pollution from the coastal area, with large emission sources to the inland mountainous region, occurs frequently in central Japan on clear summer days. Hydrocarbons and other pollutants were measured together with meteorological parameters along this route, and the diurnal variations of OH radical and hydrocarbons in the polluted air mass were investigated in relation with these photochemical reactions. At inland sampling sites, hydrocarbon concentrations in a polluted air mass decreased during LRT in the daytime. In particular, olefins were destroyed significantly because of more active photochemical reactions. From these destruction rates and/or 03 formation rates the OH radical concentration was estimated and found to increase from 0.5 x 10-7 in the morning to a maximum of 8.0 x 10-7 ppm at midday. These values, as well as the diurnal variation, compared well with the numerical result of the comprehensive transport/reaction/removal model (Chang et al., 1989, Atmospheric Environment 23, 363-393, 1749-1773). The contribution of each hydrocarbon component to the total hydrocarbon destruction was also discussed.
Journal of Geophysical Research, 2004
1] An episodic simulation is conducted to characterize ozone (O 3 ) formation and to investigate the dependence of O 3 formation on precursors in the Houston-Galveston (HG) area using a regional chemical transport model (CTM). The simulated net photochemical O 3 production rates, P(O 3 ), in the Houston area are higher than those in most other U.S. urban cities, reaching 20-40 ppb hr À1 for the daytime ground NO x levels of 5-30 ppb. The NO x turnaround value (i.e., the NO x concentration at which P(O 3 ) reaches a maximum) is also larger than those observed in most other U.S. cities. The large abundance and high reactivity of anthropogenic volatile organic compounds (AVOCs) and the coexistence of abundant AVOCs and NO x in this area are responsible for the high O 3 production rates and the NO x turnaround value. The simulated O 3 production efficiency is typically 3-8 O 3 molecules per NO x molecule oxidized during the midday hours. The simulation reveals a RO 2 peak up to 70 ppt at night, and the reactions of alkene-NO 3 and alkene-O 3 are responsible for more than 80% of the nighttime RO 2 in the residual layer, contributing to over 70% and about 10%, respectively. Isoprene accounts for about 40% of the nighttime RO 2 peak concentration. The nighttime RO 2 level is limited by the availability of alkenes. Hydrolysis of N 2 O 5 on sulfate aerosols leads to an increase of HNO 3 by as much as 30-60% but to a decrease of NO x by 20-50% during the night in the lower troposphere. Heterogeneous conversion of NO 2 to HONO on the surfaces of soot aerosol accelerates the O 3 production by about 1 hour in the morning and leads to a noticeable increase of 7 ppb on average in the daytime O 3 level. The sensitivity study suggests that the near-surface chemistry over most of the Houston metropolitan area is in or close to the NO x -VOC transition regime on the basis of the current emission inventory. Doubling AVOC emissions leads to the NO x sensitive chemistry. Biogenic VOCs contribute about 5% on the average to the total near-surface O 3 in the Houston area.
To better understand the secondary air pollution in transboundary air over westernmost Japan, ground-based field measurements of the chemical composition of fine particulate matter (≤ 1 µm), mixing ratios of trace gas species (CO, O 3 , NO x , NO y , i-pentane, toluene, and ethyne), and meteorological elements were conducted with a suite of in-strumentation. The CO mixing ratio dependence on wind direction showed that there was no significant influence from primary emission sources near the monitoring site, indicating long-and/or mid-range transport of the measured chemical species. Despite the considerably different atmospheric lifetimes of NO y and CO, these mixing ratios were correlated (r 2 = 0.67). The photochemical age of the pollutants, t[OH] (the reaction time × the mean concentration of OH radical during the atmospheric transport), was calculated from both the NO x / NO y concentration ratio (NO x / NO y clock) and the toluene / ethyne concentration ratio (hydrocarbon clock). It was found that the toluene / ethyne concentration ratio was significantly influenced by dilution with background air containing 0.16 ppbv of ethyne, causing significant bias in the estimation of t[OH]. In contrast, the influence of the reaction of NO x with O 3 , a potentially biasing reaction channel on [NO x ] / [NO y ], was small. The t[OH] values obtained with the NO x / NO y clock ranged from 2.9 × 10 5 to 1.3 × 10 8 h molecule cm −3 and were compared with the fractional contribution of the m/z 44 signal to the total signal in the organic aerosol mass spectra (f 44 , a quantitative oxidation indicator of carboxylic acids) and O 3 mixing ratio. The comparison of t[OH] with f 44 showed evidence for a systematic increase of f 44 as t[OH] increased, an indication of secondary organic aerosol (SOA) formation. To a first approximation, the f 44 increase rate was (1.05 ± 0.03) × 10 −9 × [OH] h −1 , which is comparable to the background-corrected increase rate observed during the New England Air Quality Study in summer 2002. The similarity may imply the production of similar SOA component, possibly humic-like substances. Meanwhile , the comparison of t[OH] with O 3 mixing ratio showed that there was a strong proportional relationship between O 3 mixing ratio and t[OH]. A first approximation gave the increasing rate and background mixing ratio of ozone as (3.48 ± 0.06) × 10 −7 × [OH] ppbv h −1 and 30.7 ppbv, respectively. The information given here can be used for prediction of secondary pollution magnitude in the outflow from the Asian continent.
Characteristics of background surface ozone in Japan
Atmospheric Environment, 1994
Ahatract-A study has been performed on the characteristics and behavior of background surface ozone concentrations at 10 of the background surface ozone monitoring stations in Japan. This surface ozone monitoring network was set up in the 1980s to study the diurnal, seasonal and long-term behavior of background ozone in Japan at ~remote" sites relatively unperturbed by human influences. There is seasonal variability in the measured ozone concentrations with its peak in spring and a significant summer minimum. This summer minimum is likely due to regional air flow originating from southern marine latitudes bringing relatively clean air. Diurnal behavior varies with site elevation and location relative to urban and industrial sources. The high elevation sites in Japan show significantly higher average concentrations than similar sites in Europe and the United States of America.