Spatial Distribution Of Ozone Research Articles

항공기를 이용한 남해안 지역의 오존 공간분포 조사 (2009년, 여름철)

The purpose of this study is to understand distribution of ozone concentration in the south coastal region of Korea by evaluating ozone spatial distribution in the upper air using aircraft. Sampling was carried out from May to August in 2009. The average concentration of ozone in the upper air was ranged from 32.3~90.8 ppb with its maximum concentration of 132 ppb. When it comes to the spatial distribution of ozone, ambient concentration was high in the air, 1,000 m and 500 m above the southern sea near the Gwangyang Bay area and emission sources, respectively. Daily mean concentration of NOy was 6.7~24.2 ppb and that of CO was 0.152~0.487 ppm. In addition, the concentration was appeared to be relatively high in the upper air of industrial regions and the southern seas. Meanwhile, the concentration of both and CO was high in the upper air of the emission sources regardless of latitude. As for PAN, its daily mean concentration ranged between 0.1 and 0.6 ppb with overall mean concentration of 0.2 ppb. The average concentration of VOCs was 48 ppb, and the concentration of toluene and m,p-Xylene were higher than other components.

Vertical Profile and Spatial Distribution of Ozone and Its Precursors at the Inland and Offshore of an Industrial City

This study investigated the ozone formation mechanism and air mass trajectory via simultaneous air quality sampling around the coastal region of urban Kaohsiung. Vertical concentration profiles of O3 and its precursors (NO(subscript x) and VOCs) were sampled and measured at inland and offshore sites during eight intensive sampling periods. The intensive sampling periods were divided into three categories based on meteorological condition: the sea-land breeze period, the northeastern monsoon period, and the mixed period. Vertical profile results showed that the stratification of O3 was commonly observed at 40 out of 64 sampling sites accounting for 62.5% of the total O3 measurement. The results obtained from VOCs measurement indicated that the major species of VOCs was acetone, which accounted for 16.25-64.05% of total TVOCs- C2 in the offshore region, while the major species of VOCs in the inland region was toluene, which accounted for 6.41- 43.77 % of total TVOCs-C2. Backward trajectories showed that air pollutants emitted from land sources could transport to the offshore region, resulting in a high concentration of oversea NO(subscript x) and VOCs. Major species of VOCs with high O3 formation potential were found to be aromatics in the low atmosphere around the coastal region of metro Kaohsiung.

Diagnostic evaluation of ozone production and horizontal transport in a regional photochemical air quality modeling system

Abstract A diagnostic model evaluation effort has been performed to focus on photochemical ozone formation and the horizontal transport process since they strongly impact the temporal evolution and spatial distribution of ozone (O3) within the lower troposphere. Results from the Community Multiscale Air Quality (CMAQ) modeling system are evaluated against surface and upper air measurements from field studies during summer 2002 when several high O3 episodes occurred in the eastern United States. Modeled O3 and winds are compared to research aircraft measurements and wind profiler data, respectively, to investigate whether model underestimates of daily maximum 8-h ozone concentrations during high O3 episodes might be attributable to discrepancies in either or both of these modeled processes. Comparisons of 10 AM surface O3 concentrations, which are representative of O3 levels in the residual layer aloft, revealed that model underestimation was greater at higher observed ozone levels. Mid-morning vertical ozone profiles corroborated this surface-level finding, as modeled concentrations tended to be lower than observed O3 aloft. Net ozone production efficiency (OPE) results suggested photochemical ozone formation was comparable between the model and observations with composite OPE values of 6.7 and 7.6, respectively, within the afternoon planetary boundary layer. Evaluation of wind profiles revealed modeled wind speeds with the base four-dimensional data assimilation (FDDA) approach underestimated observed speeds by more than 2 m s−1 and direction was biased by about 20° in the nocturnal residual layer aloft as coarse resolution analysis fields involved in FDDA were found to inhibit modeled winds. These differences could produce large spatial displacements in modeled and observed ozone patterns within the region. Although sensitivity simulation results with the WRF meteorological model with FDDA using all available upper air profile observations displayed improvements in capturing wind fields aloft, CMAQ maximum 8-h O3 results using the improved wind fields also underestimated observations.

The vertical distribution of ozone instantaneous radiative forcing from satellite and chemistry climate models

[1] We evaluate the instantaneous radiative forcing (IRF) of tropospheric ozone predicted by four state-of-the-art global chemistry climate models (AM2-Chem, CAM-Chem, ECHAM5-MOZ, and GISS-PUCCINI) against ozone distribution observed from the NASA Tropospheric Emission Spectrometer (TES) during August 2006. The IRF is computed through the application of an observationally constrained instantaneous radiative forcing kernels (IRFK) to the difference between TES and model-predicted ozone. The IRFK represent the sensitivity of outgoing longwave radiation to the vertical and spatial distribution of ozone under all-sky condition. Through this technique, we find total tropospheric IRF biases from −0.4 to + 0.7 W/m2 over large regions within the tropics and midlatitudes, due to ozone differences over the region in the lower and middle troposphere, enhanced by persistent bias in the upper troposphere-lower stratospheric region. The zonal mean biases also range from −30 to +50 mW/m2 for the models. However, the ensemble mean total tropospheric IRF bias is less than 0.2 W/m2 within the entire troposphere.

A study of the prediction method of the spatial distribution of ozone by kriging in Otsu city and its surrounding area

A study of the prediction method of the spatial distribution of ozone by kriging in Otsu city and its surrounding area

Spatial structure of assimilated ozone in the upper troposphere and lower stratosphere

Ozone distributions display a rich spatial structure in the upper troposphere and lower stratosphere (UTLS). This study uses in situ aircraft observations to examine how accurately such spatial distributions of ozone are represented in an assimilation of NASA's EOS‐Aura ozone data using meteorological fields from the Goddard Earth Observing System, Version 4. Total ozone columns from the Ozone Monitoring Instrument (OMI) and stratospheric profiles from the Microwave Limb Sounder (MLS) are assimilated. The results demonstrate that the dominant large‐scale ozone distribution is well‐constrained (to realistic concentrations) near 250 hPa in the UTLS. Spatial patterns and the spectral power of variations are similar in the model simulations and the assimilation. The spectral power of the analysis increments is concentrated at large scales. Thus transport, rather than direct assimilation of small‐scale features, is responsible for the spatial ozone structure in the UTLS. Consistent with the documented behavior of the Lin‐Rood transport scheme, we demonstrate that the assimilated ozone represents realistic features on spatial scales of about four‐to‐six model grid boxes (500–800 km) and that smaller scales present in the aircraft observations are represented too weakly in the modeled and assimilated ozone fields. For the assimilated ozone, this result is robust over a range of realistic model‐error‐covariance length scales. The results indicate that observations of ozone on spatial scales that constrain the large‐scale gradients are suited to producing global analyses of UTLS ozone that represent features at higher spatial resolution.

Development and application of a parallelized version of the advanced modeling system for transport, emissions, reactions and deposition of atmospheric matter (AMSTERDAM): 1. Model performance evaluation and impacts of plume–in–grid treatment

The Community Multiscale Air Quality Model (CMAQ) is a comprehensive three–dimensional “one–atmosphere” air quality model that is now routinely used to address urban, regional–scale and continental–scale multi– pollutant issues such as ozone, particulate matter, and air toxics. Several updates have been made to CMAQ by the scientific community to enhance its capabilities and to provide alternative science treatments of some of the relevant governing processes. The Advanced Modeling System for Transport, Emissions, Reactions and Deposition of Atmospheric Matter (AMSTERDAM) is one such adaptation of CMAQ that adds an Advanced Plume–in–grid Treatment (APT) for resolving sub–grid scale processes associated with emissions from elevated point sources. It also incorporates a state–of–the–science alternative treatment for aerosol processes based on the Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (MADRID). AMSTERDAM is configured to provide flexibility to the model user in selecting options for the new science modules. This paper describes the parallelization of AMSTERDAM to make it a practical tool for plume–in–grid (PinG) treatment of a large number of point sources, and presents results from its application to the central and eastern United States for summer and winter periods in 2002. Over 150 coal–fired power plants in the domain with high emissions of sulfur dioxide (SO2) and nitrogen oxides (NOX) were selected for PinG treatment in the CMAQ–MADRID–APT configuration of AMSTERDAM used for this application. Although both model configurations (grid–only and PinG) give similar model performance results (an aggregate measure of model skill), the results show significant differences between the two versions in the specific nature of the predicted spatial distribution of ozone and PM2.5 concentrations. These differences can be important in determining source contributions to ambient concentrations. A companion paper examines the differences in the predicted contributions of hypothetical source regions from the two configurations of the model.

Millimeter radio wave monitoring of the vertical distribution of ozone over Moscow

The results ofmonitoring of the vertical distribution of ozone (VDO) over Moscow using millimeter waves are presented. The features of the altitude-time distribution of ozone, which reflects the ozonosphere evolution over mid-latitudes, are considered. Changes in the VDO, characterizing the ozonosphere response to stratospheric warming in January 2009, are shown. A conclusion is made on the necessity of developing a domestic ground-based network for mm-wave monitoring of the spatial distribution of ozone.

Observed vertical distribution of tropospheric ozone during the Asian summertime monsoon

We characterize the horizontal and vertical distribution of tropospheric ozone measured by the Tropospheric Emission Spectrometer (TES) over North Africa, the Middle East, and Asia. Studies have shown that the summertime circulation associated with the Asian monsoon significantly influences the spatial distribution of ozone and its precursors. However, there have been limited observations of the distribution of tropospheric ozone over this region. Over the Middle East, TES observations reveal abundances of ozone between 60 and 100 ppbv, with amounts over 80 ppbv typically occurring between 300 and 450 hPa, whereas over India, enhanced ozone abundances are near 300 hPa. Over central Asia, observed ozone amounts are 150–200 ppbv at altitudes near 300 hPa. These enhanced ozone abundances are observed in June and July, corresponding to the onset of the Asian monsoon, and begin to dissipate in August. Intercomparison of the TES data with ozone climatologies derived from the Measurements of Ozone and Water Vapor by in‐Service Airbus Aircraft program show that the TES ozone is biased high by about 15% between 300 and 750 hPa, consistent with prior validation studies. Comparison of the assimilation of TES data into the GEOS‐Chem model with assimilation of data from the Microwave Limb Sounder (MLS) and the Ozone Monitoring Instrument (OMI) into the Goddard Earth Observing System (GEOS‐4) model shows consistency in the distribution of ozone. For example, at 7–8 km across North Africa, the Middle East, and Asia the bias between GEOS‐Chem and the assimilated OMI and MLS fields was reduced from 6.8 to 1.4 ppbv following assimilation of the TES data.

Ozone Production in the Negative DC Corona: The Dependence of Discharge Polarity

The rate of production and the spatial distribution of ozone in the negative DC corona discharge are predicted with a numerical model. The results are compared to prior experimental data and to results previously presented by the authors for the positive corona discharge. In agreement with experimental data, ozone production rate in the negative corona is an order of magnitude higher than in the positive corona. The model reveals that this significant difference is due to the effect of discharge polarity on the number of energetic electrons in the corona plasma. The number of electrons is one order of magnitude greater and the chemically reactive plasma region extends beyond the ionization region in the negative corona. The paper also extends our prior modeling effort to lower velocities where the Joule heating reduces ozone production. The magnitude of the reduction is characterized by a new dimensionless parameter referred to as the electric Damkohler's third number(DaIII–e).

Free-air fumigation of mature trees. A novel system for controlled ozone enrichment in grown-up beech and spruce canopies.

A novel system for continuous and controlled free-air fumigation of mature tree canopies with ozone is described. Ozone generated from oxygen is diluted with air in a pressurized tank and conducted into the canopies by a system of 100 PTFE tubes hanging down from a grid fixed above the crowns. With 45 calibrated outlets per tube providing a constant flow of 0.3 l/min each, a total volume of about 10*10*15 m3 comprising 5 beech and 5 spruce canopies is fumigated. The spatial ozone distribution in the fumigated volume as well as surrounding reference tree canopies is controlled by continuous measuring instruments installed at 4 levels and a dense array of passive samplers. The system will later be used for CO2 fumigation as well. Results of the first year of continuous operation, with 2 * ambient ozone levels having been achieved, are reported.

Temporal and Spatial Distributions of Ozone in Atlanta: Regulatory and Epidemiologic Implications

ABSTRACT Relationships between ambient levels of selected air pollutants and pediatric asthma exacerbation in Atlanta were studied retrospectively. As a part of this study, temporal and spatial distributions of ambient ozone concentrations in the 20-county Atlanta metropolitan area during the summers of 1993, 1994, and 1995 were assessed. A universal kriging procedure was used for spatial interpolation of aerometric monitoring station data. In this paper, the temporal and spatial distributions of ozone are described, and regulatory and epidemiologic implications are discussed. For the study period, the Atlanta ozone nonattainment area based on the 1-h, exceedance-based standard of 0.12 ppm is estimated to expand—from 56% of the Atlanta MSA by area and 71% by population to 88% by area and 96% by population—under the new 8-h, concentration-based standard of 0.08 ppm. Regarding asthma exacerbation, a 4% increase in pediatric asthma rate per 20-ppb increase in ambient ozone concentration was observed (p-value = 0.001), with ambient ozone level representing a general indicator of air quality due to its correlations with other pollutants. The use of spatial ozone estimates in the epidemiologic analysis demonstrates the need for control of demographic covariates in spatiotem poral assessments of associations of ambient air pollutant concentrations with health outcome.

ENVIRONMENTAL AUDITING: An Approach for Characterizing Tropospheric Ozone Risk to Forests

/ The risk tropospheric ozone poses to forests in the United States is dependent on the variation in ozone exposure across the distribution of the forests in question and the various environmental and climate factors predominant in the region. All these factors have a spatial nature, and consequently an approach to characterization of ozone risk is presented that places ozone exposure-response functions for species as seedlings and model-simulated tree and stand responses in a spatial context using a geographical information systems (GIS). The GIS is used to aggregate factors considered important in a risk characterization, including: (1) estimated ozone exposures over forested regions, (2) measures of ozone effects on species' and stand growth, and (3) spatially distributed environmental, genetic, and exposure influences on species' response to ozone. The GIS-based risk characterization provides an estimation of the extent and magnitude of the potential ozone impact on forests. A preliminary risk characterization demonstrating this approach considered only the eastern United States and only the limited empirical data quantifying the effect of ozone exposures on forest tree species as seedlings. The area-weighted response of the annual seedling biomass loss formed the basis for a sensitivity ranking: sensitive-aspen and black cherry (14%-33% biomass loss over 50% of their distribution); moderately sensitive-tulip popular, loblolly pine, eastern white pine, and sugar maple (5%-13% biomass loss); insensitive-Virginia pine and red maple (0%-1% loss). In the future, the GIS-based risk characterization will include process-based model simulations of the three- to 5-year growth response of individual species as large trees with relevant environmental interactions and model simulated response of mixed stands. The interactive nature of GIS provides a tool to explore consequences of the range of climate conditions across a species' distribution, forest management practices, changing ozone precursors, regulatory control strategies, and other factors influencing the spatial distribution of ozone over time as more information becomes available.KEY WORDS: Ecological risk assessment; GIS; Ozone; Risk characterization; Forests; Trees

Reaction Kinetics and Chemical Quasi‐Equilibria of the Ozone Synthesis in Oxygen DC Discharges

AbstractThe spatial distribution of ozone and of oxygen atoms was studied along the active and the passive zone of a dc discharge (positive column, pressure: p = (4 … 10) · 102 Pa, current: I = 2 … 50 mA, flow rate: F = 5 … 100 sccm) in flowing oxygen. The composition of the final output O2/O3‐mixture is controlled by relaxation processes in the passive reactor zone. It is affected sensitively by the total number density and the gas temperature in the afterglow. Steady states meaning reversible chemical quasi‐equilibria were observed and analysed extensively. Within a detailed kinetic model the formation of these equilibria can be explained quantitatively. The synthesis to ozone is controlled above all by the metastable O2 (a1Δg) species, which modify drastically the results for the basic mechanism, considering the O atoms in the 3P and 1D states.

Observations of Deformation and Mixing of the Total Ozone Field in the Antarctic Polar Vortex

Total Ozone Mapping Spectrometer images of the springtime Southern Hemisphere commonly show concentric layers in the total ozone field outside the Antarctic polar vortex. The layering appears to result from horizontal folding and stretching of regions on the equatorward flank of the polar vortex near the midlatitude ozone maximum. This folding and stretching interleaves low and high ozone air from the subtropics and midlatitudes, respectively. Occasional large amplitude wave events can extract very low ozone air from the interior of the polar vortex (the Antarctic ozone hole), but the folding and stretching occurs in midlatitudes even when wave amplitudes are not exceptionally large. The folding and stretching results in relatively rapid horizontal mixing of the atmosphere on the equatorward flank of the jet. This type of Lagrangian behavior may be common in the atmosphere, but is only visible when local tracer gradients are large and observations with high spatial resolution are available. Also, experimentation has shown that gray-scale images of TOMS data show the details of the spatial distribution of ozone much more clearly than contour maps or false-color images.

A theoretical estimate of O 3 and H 2O 2 dry deposition over the northeast United States

Estimates of short-term, regional-scale spatial distributions of ozone (O 3) and hydrogen peroxide (H 2O 2) dry deposition over the northeast U.S. are presented. Dry deposition fluxes to surfaces are computed using a regional tropospheric chemistry model with deposition velocities which vary with local meteorology, land type, insolation, seasonal factors and surface wetness. A compilation of O 3 surface resistances is presented based on a survey of O 3 dry deposition measurements. The surface resistance for H 2O 2 is assumed to be small under most conditions, causing H 2O 2 to dry deposit at a rate which is frequently limited by surface-layer turbulence. Regional patterns of dry deposition velocities for these oxidants over the northeast U.S. are computed using landuse data and meteorological information predicted using a mesoscale meteorology model. Domain-averaged O 3 deposition velocities during a spring period reach a mid-day peak of 0.7–0.8 cm s −1 and drop to 0.1–0.2 cm s −1 at night. Domain-averaged H 2O 2 deposition velocities at a height of approximately 80 m are predicted to reach a mid-day peak of 1.6–2.0cm s −1, and fall to 0.6–0.9 cm s −1 at night. Time-averaged surface-layer H 2O 2 concentrations show a latitude dependence, with higher concentrations in the south. H 2O 2 concentrations are significantly reduced due to efficient wet removal and chemical destruction during the passage of a cyclonic frontal system. In contrast, O 3 concentrations are predicted to rise during the passage of a frontal system due to efficient vertical exchange of midtropospheric air into the boundary layer during convective conditions, followed by synoptic-scale subsidence occurring in the high pressure airmass following a cyclone. Maximum O 3 deposition during this 3-day springtime period occurs in polluted agricultural areas. In contrast, H 2O 2 dry deposition exhibits a latitude dependence with maximum 3-day accumulations occurring in the south. Domain-averaged mid-day deposition rates for O 3 and H 2O 2 were 45–50 μmol m −2 h −1 and 4–5 μmol m −2 h −1. At night, deposition rates were approximately 5–10 μmol m −2 h −1 and 1.5–2.5 μmol m −2 h −1 for O 3 and H 2O 2. These model results show that regional patterns of oxidant dry deposition are strongly influenced by oxidant concentrations, atmospheric stability, surface roughness and numerous other surface and meteorological factors. Each of these factors must be well-characterized before regional patterns of biological damage associated with oxidant dry deposition can be quantified.

Solar Proton Events: Stratospheric Sources of Nitric Oxide

The production of nitric oxide (NO) in the stratosphere during each of the solar proton events of November 1960, September 1966, and August 1972 is calculated to have been comparable to or larger than the total average annual production of NO by the action of galactic cosmic rays. It is therefore very important to consider the effect of solar proton events on the temporal and spatial distribution of ozone in the stratosphere. A study of ozone distribution after such events may be particularly important for validating photochemical-diffusion models.

Ozone and Water Vapor Injected into the Stratosphere from Two Isolated Thunderstorms

Abstract The local ozone concentration and water vapor overburden were measured from a WB-57F aircraft near thunderstorms that reached or penetrated the tropopause. Two storms were studied extensively: one that penetrated 800 m above the tropopause and another that reached to about the tropopause level. In both cases, water vapor overburdens above and downwind averaged some 40% higher than those upwind of the storms. The water vapor overburdens directly above the higher storm were about 2.4 times that of those background measurements upwind and at the same levels; directly above the weaker storm the water vapor was about 1.8 times as great as the background measurements. The spatial distribution of ozone around the two storms was similar to that of the water vapor: downwind concentrations exceeded those upwind at all levels. An excess in ozone of about 25% was observed in circumnavigations above the storm tops when compared with fair-weather values at the same levels away from the storm. Ozone concentrati...