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1.
《Atmospheric environment(England)》1985,19(11):1921-1929
Ground level ozone, NOx and specific C2-C6 hydrocarbon measurements from a rural site in N-W England during a photochemical pollution episode are presented. Maximum hourly ozone concentrations exceeded 80 ppb for ten consecutive days with a maximum of 156 ppb. Mid-morning ozone concentrations were found to be indicative of the amount of ozone from continental sources. The air mass trajectories, total NMHC and alkane : alkene ratios all indicate that in the early to middle stages of the episode the air had been exposed to recent precursor emissions relative to more aged air before and after this period. The measurements are compared with the predictions of recent theoretical models of ozone formation over England. 相似文献
2.
《Atmospheric environment (Oxford, England : 1994)》1999,33(12):1821-1845
Research over the past ten years has created a more detailed and coherent view of the relation between O3 and its major anthropogenic precursors, volatile organic compounds (VOC) and oxides of nitrogen (NOx). This article presents a review of insights derived from photochemical models and field measurements. The ozone–precursor relationship can be understood in terms of a fundamental split into a NOx-senstive and VOC-sensitive (or NOx-saturated) chemical regimes. These regimes are associated with the chemistry of odd hydrogen radicals and appear in different forms in studies of urbanized regions, power plant plumes and the remote troposphere. Factors that affect the split into NOx-sensitive and VOC-sensitive chemistry include: VOC/NOx ratios, VOC reactivity, biogenic hydrocarbons, photochemical aging, and rates of meteorological dispersion. Analyses of ozone–NOx–VOC sensitivity from 3D photochemical models show a consistent pattern, but predictions for the impact of reduced NOx and VOC in indivdual locations are often very uncertain. This uncertainty can be identified by comparing predictions from different model scenarios that reflect uncertainties in meteorology, anthropogenic and biogenic emissions. Several observation-based approaches have been proposed that seek to evaluate ozone–NOx–VOC sensitivity directly from ambient measurements (including ambient VOC, reactive nitrogen, and peroxides). Observation-based approaches have also been used to evaluate emission rates, ozone production efficiency, and removal rates of chemically active species. Use of these methods in combination with models can significantly reduce the uncertainty associated with model predictions. 相似文献
3.
《Atmospheric environment(England)》1981,15(7):1309-1323
The United States has instituted a number of air pollution regulations to control ozone, including an air quality standard for oxidants of 120 ppb for one hour. Accordingly, there is considerable interest in determining the magnitude of the natural (i.e. nonanthropogenic) component of ozone concentration near the ground, much of which is generally believed to come from the stratosphere. Toward this end, an extensive program of aircraft measurements of tropospheric ozone originating from the stratosphere was carried out over the Central U.S. in spring and fall 1978. On 10 of these flights, the vertical structure of stratospheric ozone intrusions was well mapped by aircraft penetrations at several altitudes extending between 2 and 8 km above sea level (ASL) in the southern portions of tropospheric low-pressure troughs.The field measurements show that stratospheric ozone intrusions into the troposphere occur more frequently than earlier studies had indicated. Ozone intrusions were found in virtually every trough, regardless of intensity, within which suitable measurements were taken. A close relationship was found between:
- 1.(1) maximum ozone concentrations in the intrusion; and
- 2.(2) trough intensity as characterized by maximum wind speed at 300 mb (approximately 10 km ASL).
4.
《Atmospheric environment (Oxford, England : 1994)》2001,35(27):4663-4673
The effects of the solar eclipse on 11 August 1999 on surface ozone at two sites, Thessaloniki, Greece (urban site) and Hohenpeissenberg, Germany (elevated rural site) are investigated in this study and compared with model results. The eclipse offered a unique opportunity to test our understanding of tropospheric ozone chemistry and to investigate with a simple photochemical box model the response of surface ozone to changes of solar radiation during a photolytical perturbation such as the solar eclipse. The surface ozone measurements following the eclipse display a decrease of around 10–15 ppbv at the urban station of Eptapyrgio at Thessaloniki while at Hohenpeissenberg, the actual ozone data do not show any clear effect of eclipse on surface ozone. For Thessaloniki, the model results suggest that solely photochemistry can account for a significant amount of the observed surface ozone decrease during the eclipse but transport effects mask part of the photochemical effect of eclipse on surface ozone. For Hohenpeissenberg, the box model predicted an ozone decrease, due to the eclipse, of about 2 ppbv in relative agreement with the magnitude of the observed ozone decrease from the 2 h moving average while at the same time it inhibits the foreseen diurnal ozone increase. However, this modeled ozone decrease during the eclipse is small compared to the diurnal ozone variability due to transport effects, and hence, transport really masks such relative small changes. The different magnitude of the surface ozone decrease between the two sites indicates mainly the role of the NOx levels. Measured and modeled NO and NO2 concentrations at Hohenpeissenberg during the eclipse are also compared and indicate that the partitioning of NO and NO2 in NOx is influenced clearly from the eclipse. This is not observed at Thessaloniki due to local NOx sources. 相似文献
5.
《Atmospheric environment (Oxford, England : 1994)》2005,39(29):5423-5435
Using the set of multivariate criteria described in a companion paper, ozone-rich layers detected in tropospheric soundings are clustered according to their stratospheric or boundary layer origin. An additional class for aged tropospheric air masses is also considered. This analysis is exclusively based on the measured physical properties of the layers. The database includes 27,000 ozone profiles collected above 11 European stations—two of which provide measurements since 1970. The seasonal cycle of the tropospheric ozone stratification exhibits a clear summer maximum. This increase is due to aged tropospheric air masses that are more frequently detected, suggesting an enhanced lifetime of layers in summer. In terms of ozone content, the relative impact of stratospheric ozone compared to the other sources is highest in winter while export from the boundary layer presents a uniform seasonal cycle. Altitude and thickness distributions of the layers are consistent with the dynamical processes involved in the layering. Northernmost and southernmost stations are more exposed to stratospheric air intrusions into the free troposphere. Long-term trends show that transport from the tropopause region has increased since the mid 1980s. This trend being concomitant with lower ozone content of such layers, a moderate trend of the transport efficiency from the stratosphere on total tropospheric ozone is observed. The increase of ozone detected in tropospheric layers since the mid 1980s cannot be attributed to any recent export process from either the stratosphere or the boundary layer but rather to enhanced photochemical production in aged air masses or to an increase in the lifetime of the layers. 相似文献
6.
Gerhard Lammel Hartmut Graßl 《Environmental science and pollution research international》1995,2(1):40-45
Through various processes the nitrogen oxides (NOX) interact with trace gases in the troposphere and stratosphere which do absorb in the spectral range relevant to the greenhouse effect (infrared wavelengths). The net effect is an enhancement of the greenhouse effect. The catalytic role of NOX in the production of tropospheric ozone provides the most prominent contribution. The global waming potential is estimated as GWP (NOX = 30 – 33 and 7 – 10 for the respective time horizons of 20 and 100 years, and is thereby comparable to that of methane. NOX emissions in rural areas of anthropogenically influenced regions, or those in the vicinity of the txopopause caused by air traffic, cause the greenhouse effectivity to be substantially more intense. We estimate an additional 5–23 % for Germany’s contribution to the anthropogenic greenhouse effect as a result of the indirect greenhouse effects stemming from NOX. Furthermore, a small and still inaccurately defined amount of the deposited NOX which has primarily been converted into nitrates is again released from the soil into the atmosphere in the form of the long-lived greenhouse gas nitrous oxide (N2O). Thus, anthropogenically induced NOX emissions contribute to enhanced greenhouse effect and to stratospheric ozone depletion in the time scale of more than a century. 相似文献
7.
《Atmospheric environment(England)》1984,18(12):2585-2593
NO, NO2 and total reactive nitrogen, NOy, were measured using chemiluminescence throughout the troposphere. Flights were made from Frankfurt (West Germany) to Abu Dhabi (United Arab Emirates), and from Frankfurt to Sao Paulo (Brazil). NOx (NO + NO2) concentrations were determined with a FeSO4 converter and noy, with a 425°C Mo converter. NOx levels over the Northern Hemisphere at 9 km altitude were about 200 ppt. On one flight over central Europe the aircraft encountered a thunderstorm system over an area 600km wide. NOy, was markedly elevated in the area of these thunderstorms due, we believe, to the rapid transport of polluted boundary layer air into the upper troposphere. The long lifetime of these trace gases in the upper troposphere allows them to be transported to the remote atmosphere where photolysis and radical reactions could produce significant quantities of ozone. The NOy concentration of 3.5 (+0.7−0.9) ppb was significantly higher than the concentration of about 190 ppt measured on a separate flight. These and NOx data indicate that tropospheric reactive nitrogen species vary widely in concentration, and a ‘representative’ distribution may not exist. 相似文献
8.
《Atmospheric environment (Oxford, England : 1994)》2007,41(34):7262-7273
The behaviour of ozone (O3) and two important precursors, nitrogen dioxide (NO2) and formaldehyde (HCHO), over the East Mediterranean in spring from 1996 to 2002 is studied in order to characterise the buildup of tropospheric O3. The vertical distribution of O3 observed over Crete during the Photochemical Activity and Solar Ultraviolet Radiation (PAUR II) campaign in May 1999 has been used for validation of satellite-derived data. Retrievals of O3 columns from measurements of backscattered radiation by Global Ozone Monitoring Experiment (GOME) are compared with Total Ozone Mapping Spectrometer (TOMS), balloon, Systeme d’Analyse par Observation Zenithale (SAOZ) and LIDAR observations. The total O3 vertical columns vary between 270 and 402 DU and correlate well with changes in air circulation patterns. The total observed variability in tropospheric O3 is about 25 DU. Chemical box model calculations associate the GOME-observed NO2 and HCHO tropospheric columns with a potential of daily photochemical enhancement in the tropospheric O3 columns of about 0.8–1 DU over Crete and estimate the daily potential of regional photochemical buildup within upwind polluted air masses at about 2–8 DU. A Langrangian analysis attributes at most 10–20 DU of tropospheric O3 to stratosphere–troposphere exchange (STE). The remainder is attributed to long-range transport of O3 from industrial regions in Central Europe. From 1996 to 2002, in May no significant inter-annual variation in the tropospheric NO2 and HCHO columns over Crete has been observed by GOME suggesting no detectable increase in regionally produced tropospheric O3. 相似文献
9.
Kirill Ya. Kondratyev Costas A. Varotsos 《Environmental science and pollution research international》1996,3(3):153-157
An overview of the ozone issues is given including the following aspects: 1. The impact of tropospheric ozone on climate as a greenhouse gas (GHG), 2. Solar activity effects on TO and ozone concentration vertical profiles in both the troposphere and stratosphere (in cases of solar radiation absorption by the stratosphere, an unexpected problem arises via a coupling between processes of increased absorption due to “bursts” of solar activity and an enhanced destruction of ozone molecules due to the same increase resulting in weakening UV radiation absorption) and 3. Surface ozone concentration variations under conditions of polluted urban atmospheres which lead to episodes of photochemical smog formation (dangerous for human health). 相似文献
10.
Nelson A. Kelly Martin A. Ferman George T. Wolff 《Journal of the Air & Waste Management Association (1995)》2013,63(2):150-158
This analysis represents the first characterization of the photochemistry and transport of ozone in the Detroit metropolitan area and provides a basis for comparing data for Detroit to that for other cities. The characterization is based on a comprehensive set of meteorological and chemical measurements obtained at a site in the urban core of Detroit during the summer of 1981, together with measurements of O3, nitrogen oxides (NO X ), and nonmethane organic compounds (NMOC) from rural, suburban, and urban areas in southeastern Michigan and adjacent areas of Ontario. For the quartile (23 days) with highest ozone maxima (97-180 ppb), the maxima occurred 10-70 km north-northeast of the city on days that were warm and hazy with light southsouthwest winds. On such days there was a marked accumulation of ozone precursors (NMOC and NOX) in the early morning, as well as a rapid chemical removal of NO X (NO X half-life of ~5 h) from morning to midday. The timing of the daily ozone increase across the study region suggests that local photochemical generation in a moving plume was responsible for more than half of the ozone measured downwind. However, there was also evidence that ozone transported into Detroit as part of the regional background was a significant part of the O3 maxima on high ozone days. The average contributions of photochemistry and transport for the 23 days with the highest ozone maxima were estimated to be 57 ppb and 47 ppb, respectively. 相似文献
11.
《Atmospheric environment(England)》1986,20(4):665-680
A coupled one-dimensional radiative-convective and photochemical diffusion model (RCP model), which takes into account the interaction of ozone photochemistry on climate, is used to investigate the possible effects of smoke and NOx generated by a large-scale nuclear war, on vertical temperature and ozone structure and surface climate. From the results of initial experiments with fixed O3 it is found that for the nuclear smoke injection scenario adopted in this study (similar to the base line case of Turco etal., 1983), the average sunlight intensities would be reduced drastically (up to 97%), leading to a large cooling near the surface (up to 38 K) and intense heating (up to 110 K) in the upper troposphere and lower stratosphere. Variation of surface albedo, water vapour and clouds with time following the smoke injection would further enhance the surface cooling and prolong the temperature perturbation.Further experimental results with O3 photochemistry interaction indicate that for the smoke and NOx nuclear injection scenario considered in this study, the total O3 column would decrease up to 50%, with a half recovery time of about 2 y. However more than half the total O3 column reduction is caused by the heating of the stratosphere by smoke injection. The effect of stratospheric O3 reductions on surface climate is not significant (less than 2.5 K. additional cooling). However the vertical temperature profile is altered in such a way that it would lead to a large increase in the thermal stability of the troposphere, while decreasing it in the stratosphere more than in the case of fixed O3. Also discussed are the solar u.v.-B flux changes at the surface which result from the presence of smoke in the atmosphere initially and from stratospheric O3 depletions as the smoke particles are removed from the atmosphere in time. 相似文献
12.
《Atmospheric environment(England)》1978,12(11):2159-2172
Odd chlorine concentrations in the stratosphere arising from CCl2F2 and CCl3F are calculated using a one-dimensional model of diffusion and photolysis together with accurate production and release data. Odd chlorine mixing ratios are mapped as a function of eddy diffusion profile and tropospheric lifetime. The results allow quick conversion of ozone depletion estimates, obtained from complete one-dimensional modelling, from a given assumed tropospheric lifetime and diffusion profile to other assumed lifetimes.In addition to contributions to CIX from CCl2F2 and CCl3F, contributions from other chlorocarbons which have been detected in the troposphere, are assesssed. Our calculated estimate for the currently expected (January, 1977) total stratospheric CIX level is 1.5 ppb. Assuming there are no major calibration problems with current stratospheric CIX measurements, the measured stratospheric C1X levels are higher than calculated suggesting the possibility of other unidentified chlorine sources. 相似文献
13.
《Atmospheric environment (Oxford, England : 1994)》1999,33(3):369-381
Data from environmental-chamber studies and photochemical box-model simulations were used to evaluate and revise a method for developing a qualitative understanding of the sensitivity of ozone formation at a particular time and place to changes in concentrations of volatile organic compounds (VOC) and oxides of nitrogen (NOx). The revised method requires measurements of ozone, NO, and either NOx or NOy. The sensitivities of the method to biases in measurements were evaluated. The method potentially can be used for qualitative assessment of VOC versus NOx limitation, comparison with the predictions of grid-based photochemical air-quality models, and evaluation of trends over time in the relative effectiveness of VOC versus NOx controls. 相似文献
14.
《Atmospheric environment(England)》1985,19(10):1577-1587
Ozone concentration data measured in 1977–1979 and 1981–1983 at rural sites in north-west England have been analysed in relation to elevated concentrations. Overall, concentrations exceed 60 ppb on 11.2% of days, 80 ppb on 4.2% of days and reach levels in excess of 100 ppb on 1.5% of days monitored. It is concluded that photochemical pollution is the most frequent cause of elevated concentrations, and that both long-range (continental) and middle-distance (U.K. urban) sources contribute. On a smaller percentage of days, elevated ozone levels arise from enhanced intrusions of stratospheric air associated with vigorous frontal activity. The meteorological situations associated with tropospheric photochemical ozone formation are summer anticyclonic conditions, in common with other observations in the U.K. and other parts of the world. 相似文献
15.
《Atmospheric environment(England)》1986,20(4):695-703
The synoptic climatology of ozone (O3) for S Ontario has shown that, over the 1976–1981 period, average summer O3 concentrations follow a relationship similar to that reported for event analysis during periods of high O3 concentration. Highest average concentrations, 36 parts per billion (ppb), occur with ‘back of the high’ situations while lowest average concentrations (20 ppb) occur with ‘front of the high’ situations.With similar weather events in the winter, the pattern is reversed with highest average O3 concentrations on the ‘front of the high’ (19 ppb) and lowest average concentrations on the ‘back of the high’ (13 ppb). Concentration of O3 in the ‘front of the high’ sector is due in part to the intrusion of O3 in the vicinity of storms from the stratosphere. The seasonal variation of average concentrations in these situations is low, ranging from 14 to 26 ppb.The very low average concentration during the winter and fall for the ‘back of the high’ situation may be the result of scavenging by NOx from the urban/industrial areas around the Great Lakes. During the spring and summer, solar energy and warm temperatures cause the photochemical production of O3 from NOx and HCs precursors. In the fall and winter, photochemical production of O3 is either very low or absent, and the NOx consume O3 rather than produce it. Thus, average O3 concentrations for winter ‘back of the high’ situations are one-third of those in the summer months.The synoptic climatology of events during the months from May to September with maximum O3 concentrations in excess of 80 ppb indicates that 78 % of these events occur under synoptic weather classes generally indicative of back or centre of the high situations. 相似文献
16.
Mike Barna Brian Lamb Hal Westberg 《Journal of the Air & Waste Management Association (1995)》2013,63(7):1021-1034
ABSTRACT A modeling system consisting of MM5, Calmet, and Calgrid was used to investigate the sensitivity of anthropogenic volatile organic compound (VOC) and oxides of nitrogen (NOx) reductions on ozone formation within the Cascadia airshed of the Pacific Northwest. An ozone episode that occurred on July 11-14, 1996, was evaluated. During this event, high ozone levels were recorded at monitors downwind of Seattle, WA, and Portland, OR, with one monitor exceeding the 1 hr/120 ppb National Ambient Air Quality Standard (at 148 ppb), and six monitors above the proposed 8 hr/80 ppb standard (at 82-130 ppb). For this particular case, significant emissions reductions, between 25 and 75%, would be required to decrease peak ozone concentrations to desired levels. Reductions in VOC emissions alone, or a combination of reduced VOC and NOx emissions, were generally found to be most effective; reducing NOx emissions alone resulted in increased ozone in the Seattle area. When only VOC emissions were curtailed, ozone reductions occurred in the immediate vicinity of densely populated areas, while NOx reductions resulted in more widespread ozone reductions. 相似文献
17.
Deepak Pudasainee Balkrishna Sapkota Manohar Lal Shrestha Akikazu Kaga Akira Kondo Yoshio Inoue 《Atmospheric environment (Oxford, England : 1994)》2006,40(40):8081-8087
This paper summarizes the results of a yearlong continuous measurements of gaseous pollutants, NO, NO2, NOx and O3 in the ambient air at Kathmandu valley. Measured concentration of the pollutants in study area is a function of time. NO, NO2 and O3 peak occurred in succession in presence of sunlight. At the time of maximum O3 concentration most of the NOx are utilized. The diurnal cycle of ground level ozone concentrations, revealed mid-day peak with lower nocturnal concentrations and inverse relationship exists between O3 and NOx, which are evidences of photochemical O3 formation. The observed ground level ozone during monsoon is slight lower than the pre-monsoon value. Further, lack of rainfall and higher temperature, solar radiation in the pre-monsoon have given rise to the gradual build up of ozone and it is lowest during winter. Ground level ozone concentrations measured during bandha (general strike) and weekend are 19% and 13% higher than those measured during weekdays. The most effective ozone abatement strategy for Kathmandu Valley may be control of NOx emissions. 相似文献
18.
Bryan N. Duncan Yasuko Yoshida Jennifer R. Olson Sanford Sillman Randall V. Martin Lok Lamsal Yongtao Hu Kenneth E. Pickering Christian Retscher Dale J. Allen James H. Crawford 《Atmospheric environment (Oxford, England : 1994)》2010,44(18):2213-2223
We investigated variations in the relative sensitivity of surface ozone formation in summer to precursor species concentrations of volatile organic compounds (VOCs) and nitrogen oxides (NOx) as inferred from the ratio of the tropospheric columns of formaldehyde to nitrogen dioxide (the “Ratio”) from the Aura Ozone Monitoring Instrument (OMI). Our modeling study suggests that ozone formation decreases with reductions in VOCs at Ratios <1 and NOx at Ratios >2; both NOx and VOC reductions may decrease ozone formation for Ratios between 1 and 2. Using this criteria, the OMI data indicate that ozone formation became: 1. more sensitive to NOx over most of the United States from 2005 to 2007 because of the substantial decrease in NOx emissions, primarily from stationary sources, and the concomitant decrease in the tropospheric column of NO2, and 2. more sensitive to NOx with increasing temperature, in part because emissions of highly reactive, biogenic isoprene increase with temperature, thus increasing the total VOC reactivity. In cities with relatively low isoprene emissions (e.g., Chicago), the data clearly indicate that ozone formation became more sensitive to NOx from 2005 to 2007. In cities with relatively high isoprene emissions (e.g., Atlanta), we found that the increase in the Ratio due to decreasing NOx emissions was not obvious as this signal was convolved with variations in the Ratio associated with the temperature dependence of isoprene emissions and, consequently, the formaldehyde concentration. 相似文献
19.
《Atmospheric environment(England)》1986,20(11):2175-2184
The relationships between the monthly and seasonal averages of the daily 1200–1500 h O3 inflow concentrations and wind flow direction have been evaluated. The O3 measurements used are those during inflow of air parcels from upwind to rural monitoring stations outside of St. Louis, MO. The results obtained are consistent with the O3 measurements reported from other monitoring studies at rural locations both to the west and east of St. Louis. Although there is a stratospheric component to these ground level rural O3 concentrations, it is likely that most of the O3 measured during the warmer months of the year is associated with photochemical O3 formation in the planetary boundary layer and in the free troposphere. A substantial part of the increments in rural O3 concentrations which occur from west to east of St. Louis during the warmer months of the year appear best to be accounted for as a result of photochemical formation O3 precursors from anthropogenic emission sources to the east of St. Louis. Differences in the values of meteorological parameters with wind flow direction account for only a small part of the differences in O3 concentration observed. 相似文献
20.
Jin-Tai Lin Michael B. McElroy 《Atmospheric environment (Oxford, England : 1994)》2010,44(14):1726-1739
Mixing in the planetary boundary layer (PBL) affects vertical distributions of air tracers in the lower troposphere. An accurate representation of PBL mixing is critical for chemical-transport models (CTMs) for applications sensitive to simulations of the vertical profiles of tracers. The full mixing assumption in the widely used global CTM GEOS-Chem has recently been supplemented with a non-local PBL scheme. This study analyzes the impact of the non-local scheme on model representation of PBL mixing, consequences for simulations of vertical profiles of air tracers and surface air pollution, and implications for model applications to the interpretation of data retrieved from satellite remote sensing. The non-local scheme significantly improves simulations of the vertical distributions for NO2 and O3, as evaluated using aircraft measurements in summer 2004. It also reduces model biases over the U.S. by more than 10 ppb for surface ozone concentrations at night and by 2–5 ppb for peak ozone in the afternoon, as evaluated using ground observations. The application to inverse modeling of anthropogenic NOx emissions for East China using satellite retrievals of NO2 from OMI and GOME-2 suggests that the full mixing assumption results in 3–14% differences in top–down emission budgets as compared to the non-local scheme. The top–down estimate combining the non-local scheme and the Lin et al. inverse modeling approach suggests a magnitude of 6.6 TgN yr?1 for emissions of NOx over East China in July 2008 and 8.0 TgN yr?1 for January 2009, with the magnitude and seasonality in good agreement with bottom–up estimates. 相似文献