Science.gov

Sample records for 8-h averaged ozone

  1. Average ozone vertical distribution at Sodankyla based on the 1988-1991 ozone sounding data

    NASA Technical Reports Server (NTRS)

    Kyro, Esko; Rummukainen, Markku; Taalas, Petteri; Supperi, Ari

    1994-01-01

    The study presents the statistical analysis of ozone sonde data obtained at Sodankyla (67.4 deg N, 26.6 deg E) from the beginning of the sounding program on March 1988 to the end of December 1991. The Sodankyla sounding data offers the longest continuous record of the ozone vertical distribution in the European Arctic. In this paper, we present the average ozone partial pressures within each 1 km column obtained for different seasons during the almost four year long period. We believe that the data represented here are useful as an interim reference ozone atmosphere, especially considering the fact that northern Scandinavia has become a popular campaign site for the big international ozone experiments.

  2. A Kalman-filter bias correction of ozone deterministic, ensemble-averaged, and probabilistic forecasts

    SciTech Connect

    Monache, L D; Grell, G A; McKeen, S; Wilczak, J; Pagowski, M O; Peckham, S; Stull, R; McHenry, J; McQueen, J

    2006-03-20

    Kalman filtering (KF) is used to postprocess numerical-model output to estimate systematic errors in surface ozone forecasts. It is implemented with a recursive algorithm that updates its estimate of future ozone-concentration bias by using past forecasts and observations. KF performance is tested for three types of ozone forecasts: deterministic, ensemble-averaged, and probabilistic forecasts. Eight photochemical models were run for 56 days during summer 2004 over northeastern USA and southern Canada as part of the International Consortium for Atmospheric Research on Transport and Transformation New England Air Quality (AQ) Study. The raw and KF-corrected predictions are compared with ozone measurements from the Aerometric Information Retrieval Now data set, which includes roughly 360 surface stations. The completeness of the data set allowed a thorough sensitivity test of key KF parameters. It is found that the KF improves forecasts of ozone-concentration magnitude and the ability to predict rare events, both for deterministic and ensemble-averaged forecasts. It also improves the ability to predict the daily maximum ozone concentration, and reduces the time lag between the forecast and observed maxima. For this case study, KF considerably improves the predictive skill of probabilistic forecasts of ozone concentration greater than thresholds of 10 to 50 ppbv, but it degrades it for thresholds of 70 to 90 ppbv. Moreover, KF considerably reduces probabilistic forecast bias. The significance of KF postprocessing and ensemble-averaging is that they are both effective for real-time AQ forecasting. KF reduces systematic errors, whereas ensemble-averaging reduces random errors. When combined they produce the best overall forecast.

  3. DEVELOMENT AND EVALUATION OF A MODEL FOR ESTIMATING LONG-TERM AVERAGE OZONE EXPOSURES TO CHILDREN

    EPA Science Inventory

    Long-term average exposures of school-age children can be modelled using longitudinal measurements collected during the Harvard Southern California Chronic Ozone Exposure Study over a 12-month period: June, 1995-May, 1996. The data base contains over 200 young children with perso...

  4. Radiative forcing and climate metrics for ozone precursor emissions: the impact of multi-model averaging

    NASA Astrophysics Data System (ADS)

    MacIntosh, C. R.; Shine, K. P.; Collins, W. J.

    2015-04-01

    Multi-model ensembles are frequently used to assess understanding of the response of ozone and methane lifetime to changes in emissions of ozone precursors such as NOx, VOCs (volatile organic compounds) and CO. When these ozone changes are used to calculate radiative forcing (RF) (and climate metrics such as the global warming potential (GWP) and global temperature-change potential (GTP)) there is a methodological choice, determined partly by the available computing resources, as to whether the mean ozone (and methane) concentration changes are input to the radiation code, or whether each model's ozone and methane changes are used as input, with the average RF computed from the individual model RFs. We use data from the Task Force on Hemispheric Transport of Air Pollution source-receptor global chemical transport model ensemble to assess the impact of this choice for emission changes in four regions (East Asia, Europe, North America and South Asia). We conclude that using the multi-model mean ozone and methane responses is accurate for calculating the mean RF, with differences up to 0.6% for CO, 0.7% for VOCs and 2% for NOx. Differences of up to 60% for NOx 7% for VOCs and 3% for CO are introduced into the 20 year GWP. The differences for the 20 year GTP are smaller than for the GWP for NOx, and similar for the other species. However, estimates of the standard deviation calculated from the ensemble-mean input fields (where the standard deviation at each point on the model grid is added to or subtracted from the mean field) are almost always substantially larger in RF, GWP and GTP metrics than the true standard deviation, and can be larger than the model range for short-lived ozone RF, and for the 20 and 100 year GWP and 100 year GTP. The order of averaging has most impact on the metrics for NOx, as the net values for these quantities is the residual of the sum of terms of opposing signs. For example, the standard deviation for the 20 year GWP is 2-3 times larger

  5. Radiative forcing and climate metrics for ozone precursor emissions: the impact of multi-model averaging

    NASA Astrophysics Data System (ADS)

    MacIntosh, C. R.; Shine, K. P.; Collins, W. J.

    2014-10-01

    Multi-model ensembles are frequently used to assess understanding of the response of ozone and methane lifetime to changes in emissions of ozone precursors such as NOx, VOC and CO. When these ozone changes are used to calculate radiative forcing (RF) (and climate metrics such as the global warming potential (GWP) and global temperature potential (GTP)) there is a methodological choice, determined partly by the available computing resources, as to whether the mean ozone (and methane lifetime) changes are input to the radiation code, or whether each model's ozone and methane changes are used as input, with the average RF computed from the individual model RFs. We use data from the Task Force on Hemispheric Transport of Air Pollution Source-Receptor global chemical transport model ensemble to assess the impact of this choice for emission changes in 4 regions (East Asia, Europe, North America and South Asia). We conclude that using the multi-model mean ozone and methane responses is accurate for calculating the mean RF, with differences up to 0.6% for CO, 0.7% for VOC and 2% for NOx. Differences of up to 60% for NOx 7% for VOC and 3% for CO are introduced into the 20 year GWP as a result of the exponential decay terms, with similar values for the 20 years GTP. However, estimates of the SD calculated from the ensemble-mean input fields (where the SD at each point on the model grid is added to or subtracted from the mean field) are almost always substantially larger in RF, GWP and GTP metrics than the true SD, and can be larger than the model range for short-lived ozone RF, and for the 20 and 100 year GWP and 100 year GTP. We find that the effect is generally most marked for the case of NOx emissions, where the net effect is a smaller residual of terms of opposing signs. For example, the SD for the 20 year GWP is two to three times larger using the ensemble-mean fields than using the individual models to calculate the RF. Hence, while the average of multi-model fields

  6. Exponential approximation for daily average solar heating or photolysis. [of stratospheric ozone layer

    NASA Technical Reports Server (NTRS)

    Cogley, A. C.; Borucki, W. J.

    1976-01-01

    When incorporating formulations of instantaneous solar heating or photolytic rates as functions of altitude and sun angle into long range forecasting models, it may be desirable to replace the time integrals by daily average rates that are simple functions of latitude and season. This replacement is accomplished by approximating the integral over the solar day by a pure exponential. This gives a daily average rate as a multiplication factor times the instantaneous rate evaluated at an appropriate sun angle. The accuracy of the exponential approximation is investigated by a sample calculation using an instantaneous ozone heating formulation available in the literature.

  7. Version 8 SBUV Ozone Profile Trends Compared with Trends from a Zonally Averaged Chemical Model

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.; Frith, Stacey; Stolarski, Richard

    2004-01-01

    Linear regression trends for the years 1979-2003 were computed using the new Version 8 merged Solar Backscatter Ultraviolet (SBUV) data set of ozone profiles. These trends were compared to trends computed using ozone profiles from the Goddard Space Flight Center (GSFC) zonally averaged coupled model. Observed and modeled annual trends between 50 N and 50 S were a maximum in the higher latitudes of the upper stratosphere, with southern hemisphere (SH) trends greater than northern hemisphere (NH) trends. The observed upper stratospheric maximum annual trend is -5.5 +/- 0.9 % per decade (1 sigma) at 47.5 S and -3.8 +/- 0.5 % per decade at 47.5 N, to be compared with the modeled trends of -4.5 +/- 0.3 % per decade in the SH and -4.0 +/- 0.2% per decade in the NH. Both observed and modeled trends are most negative in winter and least negative in summer, although the modeled seasonal difference is less than observed. Model trends are shown to be greatest in winter due to a repartitioning of chlorine species and the increasing abundance of chlorine with time. The model results show that trend differences can occur depending on whether ozone profiles are in mixing ratio or number density coordinates, and on whether they are recorded on pressure or altitude levels.

  8. A New Method of Deriving Time-Averaged Tropospheric Column Ozone over the Tropics Using Total Ozone Mapping Spectrometer (TOMS) Radiances: Intercomparison and Analysis Using TRACE A Data

    NASA Technical Reports Server (NTRS)

    Kim, J. H.; Hudson, R. D.; Thompson, A. M.

    1996-01-01

    Error analysis of archived total 03 from total ozone mapping spectrometer (TOMS) (version 6) presented. Daily total 03 maps for the tropics, from the period October 6-21, 1992, are derived from TOMS radiances following correction for these errors. These daily maps, averaged together, show a wavelike feature, which is observed in all latitude bands, underlying sharp peaks which occur at different longitudes depending on the latitude. The wave pattern is used to derive both time-averaged stratospheric and tropospheric 03 fields. The nature of the wave pattern (stratospheric or tropospheric) cannot be determined with certainty due to missing data (no Pacific sondes, no lower stratospheric Stratospheric Aerosol and Gas Experiment (SAGE) ozone for 18 months after the Mt. Pinatubo eruption) and significant uncertainties in the corroborative satellite record in the lower stratosphere (solar backscattered ultraviolet (SBUV), microwave limb sounder (MLS)). However, the time- averaged tropospheric ozone field, based on the assumption that the wave feature is stratospheric, agrees within 10% with ultraviolet differential absorption laser Transport and Atmospheric Chemistry near the Equator-Atlantic) (TRACE A) 03 measurements from the DC-8 and with ozonesonde measurements over Brazzaville, Congo, Ascension Island, and Natal, Brazil, for the period October 6-21, 1992. The derived background (nonpolluted) Indian Ocean tropospheric ozone amount, 26 Dobson units (DU), agrees with the cleanest African ozonesonde profiles for September-October 1992. The assumption of a totally tropospheric wave (flat stratosphere) gives 38 DU above the western Indian Ocean and 15-40% disagreements with the sondes. Tropospheric column 03 is high from South America to Africa, owing to interaction of dynamics with biomass burning emissions. Comparison with fire distributions from advanced very high resolution radiometer (AVHHR) during October 1992 suggests that tropospheric 03 produced from biomass

  9. Ozone

    MedlinePlus

    ... Earth's surface. It shields us from the sun's ultraviolet rays. Part of the good ozone layer is ... enough good ozone, people may get too much ultraviolet radiation. This may increase the risk of skin ...

  10. Ozone

    MedlinePlus

    ... reactive form of oxygen. In the upper atmosphere, ozone forms a protective layer that shields us from the sun’s ultraviolet rays. At ground level, ozone is a harmful air pollutant and a primary ...

  11. Ozone

    MedlinePlus

    Ozone is a gas. It can be good or bad, depending on where it is. "Good" ozone occurs naturally about 10 to 30 miles above ... the sun's ultraviolet rays. Part of the good ozone layer is gone. Man-made chemicals have destroyed ...

  12. Uses of monoclonal antibody 8H9

    DOEpatents

    Cheung, Nai-Kong V.

    2013-04-09

    This invention provides a composition comprising an effective amount of monoclonal antibody 8H9 or a derivative thereof and a suitable carrier. This invention provides a pharmaceutical composition comprising an effective amount of monoclonal antibody 8H9 or a derivative thereof and a pharmaceutically acceptable carrier. This invention also provides an antibody other than the monoclonal antibody 8H9 comprising the complementary determining regions of monoclonal antibody 8H9 or a derivative thereof, capable of binding to the same antigen as the monoclonal antibody 8H9. This invention provides a substance capable of competitively inhibiting the binding of monoclonal antibody 8H9. This invention also provides an isolated scFv of monoclonal antibody 8H9 or a derivative thereof. This invention also provides the 8H9 antigen. This invention also provides different uses of the monoclonal antibody 8H9 or its derivative.

  13. Uses of monoclonal antibody 8H9

    DOEpatents

    Cheung, Nai-Kong V.

    2010-06-22

    This invention provides a composition comprising an effective amount of monoclonal antibody 8H9 or a derivative thereof and a suitable carrier. This invention provides a pharmaceutical composition comprising an effective amount of monoclonal antibody 8H9 or a derivative thereof and a pharmaceutically acceptable carrier. This invention also provides an antibody other than the monoclonal antibody 8H9 comprising the complementary determining regions of monoclonal antibody 8H9 or a derivative thereof, capable of binding to the same antigen as the monoclonal antibody 8H9. This invention provides a substance capable of competitively inhibiting the binding of monoclonal antibody 8H9. This invention also provides an isolated scFv of monoclonal antibody 8H9 or a derivative thereof. This invention also provides the 8H9 antigen. This invention also provides different uses of the monoclonal antibody 8H9 or its derivative.

  14. Uses of monoclonal antibody 8H9

    DOEpatents

    Cheung, Nai-Kong V

    2013-08-06

    This invention provides a composition comprising an effective amount of monoclonal antibody 8H9 or a derivative thereof and a suitable carrier. This invention provides a pharmaceutical composition comprising an effective amount of monoclonal antibody 8H9 or a derivative thereof and a pharmaceutically acceptable carrier. This invention also provides an antibody other than the monoclonal antibody 8H9 comprising the complementary determining regions of monoclonal antibody 8H9 or a derivative thereof, capable of binding to the same antigen as the monoclonal antibody 8H9. This invention provides a substance capable of competitively inhibiting the binding of monoclonal antibody 8H9. This invention also provides an isolated scFv of monoclonal antibody 8H9 or a derivative thereof. This invention also provides the 8H9 antigen. This invention also provides a method of inhibiting the growth of tumor cells comprising contacting said tumor cells with an appropriate amount of monoclonal antibody 8H9 or a derivative thereof.

  15. Uses of monoclonal antibody 8H9

    DOEpatents

    Cheung, Nai-Kong V.

    2010-06-15

    This invention provides a composition comprising an effective amount of monoclonal antibody 8H9 or a derivative thereof and a suitable carrier. This invention provides a pharmaceutical composition comprising an effective amount of monoclonal antibody 8H9 or a derivative thereof and a pharmaceutically acceptable carrier. This invention also provides an antibody other than the monoclonal antibody 8H9 comprising the complementary determining regions of monoclonal antibody 8H9 or a derivative thereof, capable of binding to the same antigen as the monoclonal antibody 8H9. This invention provides a substance capable of competitively inhibiting the binding of monoclonal antibody 8H9. This invention also provides an isolated scFv of monoclonal antibody 8H9 or a derivative thereof. This invention also provides the 8H9 antigen. This invention also provides a method of inhibiting the growth of tumor cells comprising contacting said tumor cells with an appropriate amount of monoclonal antibody 8H9 or a derivative thereof.

  16. Ozone

    SciTech Connect

    Not Available

    1988-06-01

    The author discusses the debate over whether concern about a hole in the ozone layer in Antarctic is real or science fiction. There is a growing consensus that efforts must be taken to protect the ozone layer. The issue now is not whether chlorofluorocarbons (CFCs) should be controlled and regulated but how much and how soon. The United States has urged that the production of dangerous CFCs, and any other chemicals that affect the ozone layer, be restricted immediately to current levels and that their use be reduced 95 percent over the next decade. The American position was too strong for many European nations and the Japanese. Negotiations at an international conference on the matter broke down. The breakdown is due in part to a more acute concern for environmental matters in the United States than exists in many countries. Meanwhile CFCs are linked to another environmental problem that equally threatens the world - the Greenhouse Effect. The earth is in a natural warming period, but man could be causing it to become even warmer. The Greenhouse Effect could have a catastrophic impact on mankind, although nothing has been proven yet.

  17. Uses of monoclonial antibody 8H9

    SciTech Connect

    Cheung, Nai-Kong V.

    2015-06-23

    This invention provides an antibody that binds the same antigen as that of monoclonal antibody 8H9, wherein the heavy chain CDR (Complementary Determining Region)1 comprises NYDIN, heavy chain CDR2 comprises WIFPGDGSTQY, heavy chain CDR3 comprises QTTATWFAY, and the light chain CDR1 comprises RASQSISDYLH, light chain CDR2 comprises YASQSIS, and light chain CDR3 comprises QNGHSFPLT. In another embodiment, there is provided a polypeptide that binds the same antigen as that of monoclonal antibody 8H9, wherein the polypeptide comprises NYDIN, WIFPGDGSTQY, QTTATWFAY, RASQSISDYLH, YASQSIS, and QNGHSFPLT.

  18. The Effect of Lightning NOx Production on Surface Ozone in the Continental United States

    NASA Technical Reports Server (NTRS)

    Kaynak, B.; Hu, Y.; Martin, R. V.; Russell, A. G.; Choi, Y.; Wang, Y.

    2008-01-01

    Lightning NO(x) emissions calculated using the US National Lightning Detection Network data were found to account for 30% of the total NO(x) emissions for July August 2004, a period chosen both for having higher lightning NO(x) production and high ozone levels, thus maximizing the likelihood that such emissions could impact peak ozone levels. Including such emissions led to modest, but sometimes significant increases in simulated surface ozone when using the Community Multi-scale Air Quality Model (CMAQ). Three model simulations were performed, two with the addition of lightning NO(x) emissions, and one without. Domain-wide daily maximum 8-h ozone changes due to lightning NO(x) were less than 2 ppbv in 71 % of the cases with a maximum of 10 ppbv; whereas the difference in 1-h ozone was less than 2 ppbv in 77% of the cases with a maximum of 6 ppbv. Daily maximum 1-h and 8-h ozone for grids containing O3 monitoring stations changed slightly, with more than 43% of the cases differing less than 2 ppbv. The greatest differences were 42 ppbv for both 1-h and 8-h O3 , though these tended to be on days of lower ozone. Lightning impacts on the season-wide maximum 1-h and 8-h averaged ozone decreased starting from the 1 st to 4th highest values (an average of 4th highest, 8-h values is used for attainment demonstration in the US). Background ozone values from the y-intercept of O3 versus NO(z) curve were 42.2 and 43.9 ppbv for simulations without and with lightning emissions, respectively. Results from both simulations with lightning NO(x) suggest that while North American lightning production of NO(x) can lead to significant local impacts on a few occasions, they will have a relatively small impact on typical maximum levels and determination of Policy Relevant Background levels.

  19. Ozone flux to vegetation and its relationship to plant response and ambient air quality standards

    NASA Astrophysics Data System (ADS)

    Musselman, Robert C.; Massman, William J.

    The National Ambient Air Quality Standard (NAAQS) for ozone is based on occurrences of the maximum 8 h average ambient ozone concentration. However, biologists have recommended a cumulative ozone exposure parameter to protect vegetation. In this paper we propose a third alternative which uses quantifiable flux-based numerical parameters as a replacement for cumulative ambient parameters. Herein we discuss the concept of ozone flux as it relates to plant response and the NAAQS, and document information needed before a flux-based ozone NAAQS for vegetation can be implemented. Additional research is needed in techniques for determining plant uptake and in the quantification of plant defensive mechanisms to ozone. Models which include feedback mechanisms should be developed to relate ozone flux, loading, and detoxification with photosynthesis and plant productivity.

  20. Surface Ozone Background in the United States: Canadian and Mexican Pollution Influences

    EPA Science Inventory

    We use a global chemical transport model (GEOS-Chem) with 1° x 1° horizontal resolution to quantify the effects of anthropogenic emissions from Canada, Mexico, and outside North America on daily maximum 8-h average ozone concentrations in U.S.surface air.

  1. Averaging kernel prediction from atmospheric and surface state parameters based on multiple regression for nadir-viewing satellite measurements of carbon monoxide and ozone

    NASA Astrophysics Data System (ADS)

    Worden, H. M.; Edwards, D. P.; Deeter, M. N.; Fu, D.; Kulawik, S. S.; Worden, J. R.; Arellano, A.

    2013-07-01

    A current obstacle to the observation system simulation experiments (OSSEs) used to quantify the potential performance of future atmospheric composition remote sensing systems is a computationally efficient method to define the scene-dependent vertical sensitivity of measurements as expressed by the retrieval averaging kernels (AKs). We present a method for the efficient prediction of AKs for multispectral retrievals of carbon monoxide (CO) and ozone (O3) based on actual retrievals from MOPITT (Measurements Of Pollution In The Troposphere) on the Earth Observing System (EOS)-Terra satellite and TES (Tropospheric Emission Spectrometer) and OMI (Ozone Monitoring Instrument) on EOS-Aura, respectively. This employs a multiple regression approach for deriving scene-dependent AKs using predictors based on state parameters such as the thermal contrast between the surface and lower atmospheric layers, trace gas volume mixing ratios (VMRs), solar zenith angle, water vapor amount, etc. We first compute the singular value decomposition (SVD) for individual cloud-free AKs and retain the first three ranked singular vectors in order to fit the most significant orthogonal components of the AK in the subsequent multiple regression on a training set of retrieval cases. The resulting fit coefficients are applied to the predictors from a different test set of test retrievals cased to reconstruct predicted AKs, which can then be evaluated against the true retrieval AKs from the test set. By comparing the VMR profile adjustment resulting from the use of the predicted vs. true AKs, we quantify the CO and O3 VMR profile errors associated with the use of the predicted AKs compared to the true AKs that might be obtained from a computationally expensive full retrieval calculation as part of an OSSE. Similarly, we estimate the errors in CO and O3 VMRs from using a single regional average AK to represent all retrievals, which has been a common approximation in chemical OSSEs performed to date

  2. Ozone reaction with interior building materials: Influence of diurnal ozone variation, temperature and humidity

    NASA Astrophysics Data System (ADS)

    Rim, Donghyun; Gall, Elliott T.; Maddalena, Randy L.; Nazaroff, William W.

    2016-01-01

    Elevated tropospheric ozone concentrations are associated with increased morbidity and mortality. Indoor ozone chemistry affects human exposure to ozone and reaction products that also may adversely affect health and comfort. Reactive uptake of ozone has been characterized for many building materials; however, scant information is available on how diurnal variation of ambient ozone influences ozone reaction with indoor surfaces. The primary objective of this study is to investigate ozone-surface reactions in response to a diurnally varying ozone exposure for three common building materials: ceiling tile, painted drywall, and carpet tile. A secondary objective is to examine the effects of air temperature and humidity. A third goal is to explore how conditioning of materials in an occupied office building might influence subsequent ozone-surface reactions. Experiments were performed at bench-scale with inlet ozone concentrations varied to simulate daytime (ozone elevated) and nighttime (ozone-free in these experiments) periods. To simulate office conditions, experiments were conducted at two temperatures (22 °C and 28 °C) and three relative humidity values (25%, 50%, 75%). Effects of indoor surface exposures were examined by placing material samples in an occupied office and repeating bench-scale characterization after exposure periods of 1 and 2 months. Deposition velocities were observed to be highest during the initial hour of ozone exposure with slow decrease in the subsequent hours of simulated daytime conditions. Daily-average ozone reaction probabilities for fresh materials are in the respective ranges of (1.7-2.7) × 10-5, (2.8-4.7) × 10-5, and (3.0-4.5) × 10-5 for ceiling tile, painted drywall, and carpet tile. The reaction probability decreases by 7%-47% across the three test materials after two 8-h periods of ozone exposure. Measurements with the samples from an occupied office reveal that deposition velocity can decrease or increase with time

  3. Which metric of ambient ozone to predict daily mortality?

    NASA Astrophysics Data System (ADS)

    Moshammer, Hanns; Hutter, Hans-Peter; Kundi, Michael

    2013-02-01

    It is well known that ozone concentration is associated with daily cause specific mortality. But which ozone metric is the best predictor of the daily variability in mortality? We performed a time series analysis on daily deaths (all causes, respiratory and cardiovascular causes as well as death in elderly 65+) in Vienna for the years 1991-2009. We controlled for seasonal and long term trend, day of the week, temperature and humidity using the same basic model for all pollutant metrics. We found model fit was best for same day variability of ozone concentration (calculated as the difference between daily hourly maximum and minimum) and hourly maximum. Of these the variability displayed a more linear dose-response function. Maximum 8 h moving average and daily mean value performed not so well. Nitrogen dioxide (daily mean) in comparison performed better when previous day values were assessed. Same day ozone and previous day nitrogen dioxide effect estimates did not confound each other. Variability in daily ozone levels or peak ozone levels seem to be a better proxy of a complex reactive secondary pollutant mixture than daily average ozone levels in the Middle European setting. If this finding is confirmed this would have implications for the setting of legally binding limit values.

  4. The influence of meteorological factors and biomass burning on surface ozone concentrations at Tanah Rata, Malaysia

    NASA Astrophysics Data System (ADS)

    Toh, Ying Ying; Lim, Sze Fook; von Glasow, Roland

    2013-05-01

    The surface ozone concentrations at the Tanah Rata regional Global Atmosphere Watch (GAW) station, Malaysia (4°28‧N, 101°23‧E, 1545 m above Mean Sea Level (MSL)) from June 2006 to August 2008 were analyzed in this study. Overall the ozone mixing ratios are very low; the seasonal variations show the highest mixing ratios during the Southwest monsoon (average 19.1 ppb) and lowest mixing ratios during the spring intermonsoon (average 14.2 ppb). The diurnal variation of ozone is characterised by an afternoon maximum and night time minimum. The meteorological conditions that favour the formation of high ozone levels at this site are low relative humidity, high temperature and minimum rainfall. The average ozone concentration is lower during precipitation days compared to non-precipitation days. The hourly averaged ozone concentrations show significant correlations with temperature and relative humidity during the Northeast monsoon and spring intermonsoon. The highest concentrations are observed when the wind is blowing from the west. We found an anticorrelation between the atmospheric pressure tide and ozone concentrations. The ozone mixing ratios do not exceed the recommended Malaysia Air Quality Guidelines for 1-h and 8-h averages. Five day backward trajectories on two high ozone episodes in 07 August 2006 (40.0 ppb) and 24 February 2008 (45.7 ppb) are computed using the HYbrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to investigate the origin of the pollutants and influence of regional transport. The high ozone episode during 07 August 2006 (burning season during southwest monsoon) is mainly attributed to regional transport from biomass burning in Sumatra, whereas favourable meteorological conditions (i.e. low relative humidity, high temperature and solar radiation, zero rainfall) and long range transport from Indo-China have elevated the ozone concentrations during 24 February 2008.

  5. Contributors to ozone episodes in three US/Mexico border twin-cities.

    PubMed

    Shi, Chune; Fernando, H J S; Yang, Jie

    2009-09-01

    The Process Analysis tools of the Community Multiscale Air Quality (CMAQ) modeling system together with back-trajectory analysis were used to assess potential contributors to ozone episodes that occurred during June 1-4, 2006, in three populated U.S.-Mexico border twin cities: San Diego/Tijuana, Imperial/Mexicali and El Paso/Ciudad Juárez. Validation of CMAQ output against surface ozone measurements indicates that the predictions are acceptable with regard to commonly recommended statistical standards and comparable to other reported studies. The mean normalized bias test (MNBT) and mean normalized gross error (MNGE) for hourly ozone fall well within the US EPA suggested range of +/-15% and 35%, respectively, except MNBT for El Paso. The MNBTs for maximum 8-h average ozone are larger than those for hourly ozone, but all the simulated maximum 8-h average ozone are within a factor of 2 of those measured in all three regions. The process and back-trajectory analyses indicate that the main sources of daytime ground-level ozone are the local photochemical production and regional transport. By integrating the effects of each process over the depth of the daytime planetary boundary layer (PBL), it is found that in the San Diego area (SD), chemistry and vertical advection contributed about 36%/48% and 64%/52% for June 2 and 3, respectively. This confirms the previous finding that high-altitude regional transport followed by fumigation contributes significantly to ozone in SD. The back-trajectory analysis shows that this ozone was mostly transported from the coastal area of southern California. For the episodes in Imperial Valley and El Paso, respectively, ozone was transported from the coastal areas of southern California and Mexico and from northern Texas and Oklahoma. PMID:19559465

  6. Synoptic and meteorological drivers of extreme ozone concentrations over Europe

    NASA Astrophysics Data System (ADS)

    Otero, N.; Sillmann, J.; Schnell, J. L.; Rust, H. W.; Butler, T.

    2016-02-01

    The present work assesses the relationship between local and synoptic meteorological conditions and surface ozone concentration over Europe in spring and summer months, during the period 1998-2012 using a new interpolated data set of observed surface ozone concentrations over the European domain. Along with local meteorological conditions, the influence of large-scale atmospheric circulation on surface ozone is addressed through a set of airflow indices computed with a novel implementation of a grid-by-grid weather type classification across Europe. Drivers of surface ozone over the full distribution of maximum daily 8 h average values are investigated, along with drivers of the extreme high percentiles and exceedances or air quality guideline thresholds. Three different regression techniques are applied: multiple linear regression to assess the drivers of maximum daily ozone, logistic regression to assess the probability of threshold exceedances and quantile regression to estimate the meteorological influence on extreme values, as represented by the 95th percentile. The relative importance of the input parameters (predictors) is assessed by a backward stepwise regression procedure that allows the identification of the most important predictors in each model. Spatial patterns of model performance exhibit distinct variations between regions. The inclusion of the ozone persistence is particularly relevant over southern Europe. In general, the best model performance is found over central Europe, where the maximum temperature plays an important role as a driver of maximum daily ozone as well as its extreme values, especially during warmer months.

  7. Antarctic Ozone Hole, 2000

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Each spring the ozone layer over Antarctica nearly disappears, forming a 'hole' over the entire continent. The hole is created by the interaction of some man-made chemicals-freon, for example-with Antarctica's unique weather patterns and extremely cold temperatures. Ozone in the stratosphere absorbs ultraviolet radiation from the sun, thereby protecting living things. Since the ozone hole was discovered many of the chemicals that destroy ozone have been banned, but they will remain in the atmosphere for decades. In 2000, the ozone hole grew quicker than usual and exceptionally large. By the first week in September the hole was the largest ever-11.4 million square miles. The top image shows the average total column ozone values over Antarctica for September 2000. (Total column ozone is the amount of ozone from the ground to the top of the atmosphere. A relatively typical measurement of 300 Dobson Units is equivalent to a layer of ozone 0.12 inches thick on the Earth's surface. Levels below 220 Dobson Units are considered to be significant ozone depletion.) The record-breaking hole is likely the result of lower than average ozone levels during the Antarctic fall and winter, and exceptionally cold temperatures. In October, however (bottom image), the hole shrank dramatically, much more quickly than usual. By the end of October, the hole was only one-third of it's previous size. In a typical year, the ozone hole does not collapse until the end of November. NASA scientists were surprised by this early shrinking and speculate it is related to the region's weather. Global ozone levels are measured by the Total Ozone Mapping Spectrometer (TOMS). For more information about ozone, read the Earth Observatory's ozone fact sheet, view global ozone data and see these ozone images. Images by Greg Shirah, NASA GSFC Scientific Visualization Studio.

  8. Spatial variations of ground level ozone concentrations in areas of different scales

    NASA Astrophysics Data System (ADS)

    Lin, Tsai-Yin; Young, Li-Hao; Wang, Chiu-Sen

    The spatial variation of ground level ozone concentrations was investigated for areas of three different scales: (1) an air quality management district (a region about 100×70 km 2) in northern Taiwan, (2) the neighborhood (about 2 km in radius) of an air quality monitoring station, and (3) an open field (about 400×600 m 2) surrounded by 3- and 4-story buildings in an elementary school. Analysis of data on hourly ozone concentration, obtained at 13 m above the ground at 21 monitoring stations in the air quality management district, showed that the stations downwind of the urban center in the district had significantly higher ozone concentrations. Measurements for 8-h average ozone concentrations at 1.5 m above the ground by passive samplers showed that, in a flat area about 2 km in radius, the ratios of the ozone concentration at open areas to that at the monitoring station (0.86-0.93) were significantly higher than those obtained at areas with higher traffic flow and density of buildings (0.60-0.68). For the open field in an elementary school, the 8-h average ozone concentrations at 1.5 m above the ground at sites less than 10 m from the nearest building were considerably lower than those at sites farther away from buildings. The results indicated that, in areas of small scales, the spatial distributions of ozone concentration were highly non-uniform and there were appreciable day-to-day variability in spatial distribution. Such variability should be taken into account in determining the extent to which an individual is exposed to ozone.

  9. Significant increase of surface ozone at a rural site, north of eastern China

    NASA Astrophysics Data System (ADS)

    Ma, Zhiqiang; Xu, Jing; Quan, Weijun; Zhang, Ziyin; Lin, Weili; Xu, Xiaobin

    2016-03-01

    Ozone pollution in eastern China has become one of the top environmental issues. Quantifying the temporal trend of surface ozone helps to assess the impacts of the anthropogenic precursor reductions and the likely effects of emission control strategies implemented. In this paper, ozone data collected at the Shangdianzi (SDZ) regional atmospheric background station from 2003 to 2015 are presented and analyzed to obtain the variation in the trend of surface ozone in the most polluted region of China, north of eastern China or the North China Plain. A modified Kolmogorov-Zurbenko (KZ) filter method was performed on the maximum daily average 8 h (MDA8) concentrations of ozone to separate the contributions of different factors from the variation of surface ozone and remove the influence of meteorological fluctuations on surface ozone. Results reveal that the short-term, seasonal and long-term components of ozone account for 36.4, 57.6 and 2.2 % of the total variance, respectively. The long-term trend indicates that the MDA8 has undergone a significant increase in the period of 2003-2015, with an average rate of 1.13 ± 0.01 ppb year-1 (R2 = 0.92). It is found that meteorological factors did not significantly influence the long-term variation of ozone and the increase may be completely attributed to changes in emissions. Furthermore, there is no significant correlation between the long-term O3 and NO2 trends. This study suggests that emission changes in VOCs might have played a more important role in the observed increase of surface ozone at SDZ.

  10. Ozone Layer Observations

    NASA Technical Reports Server (NTRS)

    McPeters, Richard; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    The US National Aeronautics and Space Administration (NASA) has been monitoring the ozone layer from space using optical remote sensing techniques since 1970. With concern over catalytic destruction of ozone (mid-1970s) and the development of the Antarctic ozone hole (mid-1980s), long term ozone monitoring has become the primary focus of NASA's series of ozone measuring instruments. A series of TOMS (Total Ozone Mapping Spectrometer) and SBUV (Solar Backscatter Ultraviolet) instruments has produced a nearly continuous record of global ozone from 1979 to the present. These instruments infer ozone by measuring sunlight backscattered from the atmosphere in the ultraviolet through differential absorption. These measurements have documented a 15 Dobson Unit drop in global average ozone since 1980, and the declines in ozone in the antarctic each October have been far more dramatic. Instruments that measure the ozone vertical distribution, the SBUV and SAGE (Stratospheric Aerosol and Gas Experiment) instruments for example, show that the largest changes are occurring in the lower stratosphere and upper troposphere. The goal of ozone measurement in the next decades will be to document the predicted recovery of the ozone layer as CFC (chlorofluorocarbon) levels decline. This will require a continuation of global measurements of total column ozone on a global basis, but using data from successor instruments to TOMS. Hyperspectral instruments capable of measuring in the UV will be needed for this purpose. Establishing the relative roles of chemistry and dynamics will require instruments to measure ozone in the troposphere and in the stratosphere with good vertical resolution. Instruments that can measure other chemicals important to ozone formation and destruction will also be needed.

  11. Quantifying the contribution of inflow on surface ozone over California during summer 2008

    NASA Astrophysics Data System (ADS)

    Pfister, Gabriele G.; Walters, Stacy; Emmons, Louisa K.; Edwards, David P.; Avise, Jeremy

    2013-11-01

    pollution has been recognized as making a potentially strong impact on air quality in the western U.S., but large uncertainties remain in quantifying its contribution. Assessing the role of pollution transport in relation to local emissions and meteorology is especially important in light of possibly lower ozone standards and projected increases in transpacific pollution transport. We apply the Weather Research and Forecasting with Chemistry model to analyze the role of upwind pollution ("inflow") to surface ozone over California during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites campaign in June-July 2008 over California. Comparisons of the model to surface and aircraft observations, ozonesondes, and satellite retrievals show an overall good agreement; a low bias (~5 ppb) in free tropospheric ozone is attributed to low ozone at the boundaries and likely places our estimated inflow contribution on the lower side. Most other studies applied sensitivity analyses, while we use a synthetic ozone tracer, which provides a quantitative estimate of the budget. We estimate that on average 10 ± 9 ppb of surface afternoon ozone over California is attributed to ozone and ozone precursors entering the region from outside. This contribution features a significant spatial and temporal variability. While in most high ozone events, transported pollution plays a small role compared to local influences, for some instances, the impact can be substantial. Omitting data impacted by wildfires, we estimate the 90th percentile of the relative contribution of O3INFLOW to 8 h ozone >75 ppb as 10%. Our results also indicate that inflow might have a stronger impact on surface ozone in less polluted compared to polluted areas.

  12. Long-term ambient ozone concentration and the incidence of asthma in nonsmoking adults: The Ahsmog study

    SciTech Connect

    McDonnell, W.F.; Abbey, D.E.; Nishino, N.; Lebowitz, M.D.

    1999-02-01

    The authors conducted a prospective study of a cohort of 3091 nonsmokers, ages 27 to 87 years, to evaluate the association between long-term ambient ozone exposure and development of adult-onset asthma. Over a 15-year period, 3.2% of males and 4.3% of females reported new doctor diagnoses of asthma. For males, they observed a significant relationship between report of doctor diagnosis of asthma and 20-year mean 8-h average ambient ozone concentration. The authors observed no such relationship for females. Other variables significantly related to development of asthma were a history of ever-smoking for males, and for females, number of years worked with a smoker, age, and a history of childhood pneumonia or bronchitis. Addition of other pollutants to the models did not diminish the relationship between ozone and asthma for males. These data suggest that long-term exposure to ambient ozone is associated with development of asthma in adult males.

  13. Ozone and NOx chemistry in the eastern US: evaluation of CMAQ/CB05 with satellite (OMI) data

    NASA Astrophysics Data System (ADS)

    Canty, T. P.; Hembeck, L.; Vinciguerra, T. P.; Anderson, D. C.; Goldberg, D. L.; Carpenter, S. F.; Allen, D. J.; Loughner, C. P.; Salawitch, R. J.; Dickerson, R. R.

    2015-10-01

    Regulatory air quality models, such as the Community Multiscale Air Quality model (CMAQ), are used by federal and state agencies to guide policy decisions that determine how to best achieve adherence with National Ambient Air Quality Standards for surface ozone. We use observations of ozone and its important precursor NO2 to test the representation of the photochemistry and emission of ozone precursors within CMAQ. Observations of tropospheric column NO2 from the Ozone Monitoring Instrument (OMI), retrieved by two independent groups, show that the model overestimates urban NO2 and underestimates rural NO2 under all conditions examined for July and August 2011 in the US Northeast. The overestimate of the urban to rural ratio of tropospheric column NO2 for this baseline run of CMAQ (CB05 mechanism, mobile NOx emissions from the National Emissions Inventory; isoprene emissions from MEGAN v2.04) suggests this model may underestimate the importance of interstate transport of NOx. This CMAQ simulation leads to a considerable overestimate of the 2-month average of 8 h daily maximum surface ozone in the US Northeast, as well as an overestimate of 8 h ozone at AQS sites during days when the state of Maryland experienced NAAQS exceedances. We have implemented three changes within CMAQ motivated by OMI NO2 as well as aircraft observations obtained in July 2011 during the NASA DISCOVER-AQ campaign: (a) the modeled lifetime of organic nitrates within CB05 has been reduced by a factor of 10, (b) emissions of NOx from mobile sources has been reduced by a factor of 2, and (c) isoprene emissions have been reduced by using MEGAN v2.10 rather than v2.04. Compared to the baseline simulation, the CMAQ run using all three of these changes leads to considerably better simulation of column NO2 in both urban and rural areas, better agreement with the 2-month average of daily 8 h maximum ozone in the US Northeast, fewer number of false positives of an ozone exceedance throughout the domain

  14. Ozone and NOx chemistry in the eastern US: evaluation of CMAQ/CB05 with satellite (OMI) data

    NASA Astrophysics Data System (ADS)

    Canty, T. P.; Hembeck, L.; Vinciguerra, T. P.; Anderson, D. C.; Goldberg, D. L.; Carpenter, S. F.; Allen, D. J.; Loughner, C. P.; Salawitch, R. J.; Dickerson, R. R.

    2015-02-01

    Regulatory air quality models, such as the Community Multiscale Air Quality model (CMAQ), are used by federal and state agencies to guide policy decisions that determine how to best achieve adherence with National Ambient Air Quality Standards for surface ozone. We use observations of ozone and its important precursor NO2 to test the representation of the photochemistry and emission of ozone precursors within CMAQ. Observations of tropospheric column NO2 from the Ozone Monitoring Instrument (OMI), retrieved by two independent groups, show that the model overestimates urban NO2 and underestimates rural NO2 under all conditions examined for July and August 2011 in the US Northeast. The overestimate of the urban to rural ratio of tropospheric column NO2 for this baseline run of CMAQ (CB05 mechanism, mobile NOx emissions from the National Emissions Inventory; isoprene emissions from MEGAN v2.04) suggests this model may under estimate the importance of interstate transport of NOx. This CMAQ simulation leads to a considerable overestimate of the 2 month average of 8 h daily maximum surface ozone in the US Northeast, as well as an overestimate of 8 h ozone at AQS sites during days when the state of Maryland experienced NAAQS exceedances. We have implemented three changes within CMAQ motivated by OMI NO2 as well as aircraft observations obtained in July 2011 during the NASA DISCOVER-AQ campaign: (a) the modeled lifetime of organic nitrates within CB05 has been reduced by a factor of 10, (b) emissions of NOx from mobile sources has been reduced by a factor of 2, and (c) isoprene emissions have been reduced by using MEGAN v2.10 rather than v2.04. Compared to the baseline simulation, the CMAQ run using all three of these changes leads to a considerably better simulation of the ratio of urban to rural column NO2, better agreement with the 2 month average of daily 8 h maximum ozone in the US Northeast, fewer number of false positives of an ozone exceedance throughout the domain

  15. A Total Ozone Dependent Ozone Profile Climatology Based on Ozone-Sondes and Aura MLS Data

    NASA Astrophysics Data System (ADS)

    Labow, G. J.; McPeters, R. D.; Ziemke, J. R.

    2014-12-01

    A new total ozone-based ozone profile climatology has been created for use in satellite and/or ground based ozone retrievals. This climatology was formed by combining data from the Microwave Limb Sounder (MLS) with data from balloon sondes and binned by zone and total ozone. Because profile shape varies with total column ozone, this climatology better captures the ozone variations than the previously used seasonal climatologies, especially near the tropopause. This is significantly different than ozone climatologies used in the past as there is no time component. The MLS instrument on Aura has excellent latitude coverage and measures ozone profiles daily from the upper troposphere to the lower mesosphere at ~3.5 km resolution. Almost a million individual MLS ozone measurements are merged with data from over 55,000 ozonesondes which are then binned as a function of total ozone. The climatology consists of average ozone profiles as a function of total ozone for six 30 degree latitude bands covering altitudes from 0-75 km (in Z* pressure altitude coordinates). This new climatology better represents the profile shape as a function of total ozone than previous climatologies and shows some remarkable and somewhat unexpected correlations between total ozone and ozone in the lower altitudes, particularly in the lower and middle troposphere. These data can also be used to infer biases and errors in either the MLS retrievals or ozone sondes.

  16. A 15-year climatology of wind pattern impacts on surface ozone in Houston, Texas

    NASA Astrophysics Data System (ADS)

    Souri, Amir Hossein; Choi, Yunsoo; Li, Xiangshang; Kotsakis, Alexander; Jiang, Xun

    2016-06-01

    Houston is recognized for its large petrochemical industrial facilities providing abundant radicals for tropospheric ozone formation. Fortunately, maximum daily 8-h average (MDA8) surface ozone concentrations have declined in Houston (- 0.6 ± 0.3 ppbv yr- 1) during the summers (i.e., May to September) of 2000 to 2014, possibly due to the reductions in precursor emissions by effective control policies. However, it is also possible that changes in meteorological variables have affected ozone concentrations. This study focused on the impact of long-term wind patterns which have the highest impact on ozone in Houston. The analysis of long-term wind patterns can benefit surface ozone studies by 1) providing wind patterns that distinctly changed ozone levels, 2) investigating the frequency of patterns and the respective changes and 3) estimating ozone trends in specific wind patterns that local emissions are mostly involved, thus separating emissions impacts from meteorology to some extent. To this end, the 900-hPa flow patterns in summers of 2000 to 2014 were clustered in seven classes (C1-C7) by deploying an unsupervised partitioning method. We confirm the characteristics of the clusters from a backward trajectory analysis, monitoring networks, and a regional chemical transport model simulation. The results indicate that Houston has experienced a statistically significant downward trend (- 0.6 ± 0.4 day yr- 1) of the cluster of weak easterly and northeasterly days (C4), when the highest fraction of ozone exceedances (MDA8 > 70 ppbv) occurred. This suggests that the reduction in ozone precursors was not the sole reason for the decrease in ozone exceedance days (- 1.5 ± 0.6 day yr- 1). Further, to examine the efficiency of control policies intended to reduce the amount of ozone, we estimated the trend of MDA8 ozone in C4 and C5 (weak winds) days when local emissions are primarily responsible for high ambient ozone levels. Both C4 and C5 show a large reduction in the

  17. Setting maximum emission rates from ozone emitting consumer appliances in the United States and Canada

    NASA Astrophysics Data System (ADS)

    Morrison, Glenn; Shaughnessy, Richard; Shu, Shi

    2011-02-01

    A Monte Carlo analysis of indoor ozone levels in four cities was applied to provide guidance to regulatory agencies on setting maximum ozone emission rates from consumer appliances. Measured distributions of air exchange rates, ozone decay rates and outdoor ozone levels at monitoring stations were combined with a steady-state indoor air quality model resulting in emission rate distributions (mg h -1) as a function of % of building hours protected from exceeding a target maximum indoor concentration of 20 ppb. Whole-year, summer and winter results for Elizabeth, NJ, Houston, TX, Windsor, ON, and Los Angeles, CA exhibited strong regional differences, primarily due to differences in air exchange rates. Infiltration of ambient ozone at higher average air exchange rates significantly reduces allowable emission rates, even though air exchange also dilutes emissions from appliances. For Houston, TX and Windsor, ON, which have lower average residential air exchange rates, emission rates ranged from -1.1 to 2.3 mg h -1 for scenarios that protect 80% or more of building hours from experiencing ozone concentrations greater than 20 ppb in summer. For Los Angeles, CA and Elizabeth, NJ, with higher air exchange rates, only negative emission rates were allowable to provide the same level of protection. For the 80th percentile residence, we estimate that an 8-h average limit concentration of 20 ppb would be exceeded, even in the absence of an indoor ozone source, 40 or more days per year in any of the cities analyzed. The negative emission rates emerging from the analysis suggest that only a zero-emission rate standard is prudent for Los Angeles, Elizabeth, NJ and other regions with higher summertime air exchange rates. For regions such as Houston with lower summertime air exchange rates, the higher emission rates would likely increase occupant exposure to the undesirable products of ozone reactions, thus reinforcing the need for zero-emission rate standard.

  18. Gridded global surface ozone metrics for atmospheric chemistry model evaluation

    NASA Astrophysics Data System (ADS)

    Sofen, E. D.; Bowdalo, D.; Evans, M. J.; Apadula, F.; Bonasoni, P.; Cupeiro, M.; Ellul, R.; Galbally, I. E.; Girgzdiene, R.; Luppo, S.; Mimouni, M.; Nahas, A. C.; Saliba, M.; Tørseth, K.

    2016-02-01

    The concentration of ozone at the Earth's surface is measured at many locations across the globe for the purposes of air quality monitoring and atmospheric chemistry research. We have brought together all publicly available surface ozone observations from online databases from the modern era to build a consistent data set for the evaluation of chemical transport and chemistry-climate (Earth System) models for projects such as the Chemistry-Climate Model Initiative and Aer-Chem-MIP. From a total data set of approximately 6600 sites and 500 million hourly observations from 1971-2015, approximately 2200 sites and 200 million hourly observations pass screening as high-quality sites in regionally representative locations that are appropriate for use in global model evaluation. There is generally good data volume since the start of air quality monitoring networks in 1990 through 2013. Ozone observations are biased heavily toward North America and Europe with sparse coverage over the rest of the globe. This data set is made available for the purposes of model evaluation as a set of gridded metrics intended to describe the distribution of ozone concentrations on monthly and annual timescales. Metrics include the moments of the distribution, percentiles, maximum daily 8-hour average (MDA8), sum of means over 35 ppb (daily maximum 8-h; SOMO35), accumulated ozone exposure above a threshold of 40 ppbv (AOT40), and metrics related to air quality regulatory thresholds. Gridded data sets are stored as netCDF-4 files and are available to download from the British Atmospheric Data Centre (doi: 10.5285/08fbe63d-fa6d-4a7a-b952-5932e3ab0452). We provide recommendations to the ozone measurement community regarding improving metadata reporting to simplify ongoing and future efforts in working with ozone data from disparate networks in a consistent manner.

  19. Tempo-Spatial Variations of Ambient Ozone-Mortality Associations in the USA: Results from the NMMAPS Data.

    PubMed

    Liu, Tao; Zeng, Weilin; Lin, Hualiang; Rutherford, Shannon; Xiao, Jianpeng; Li, Xing; Li, Zhihao; Qian, Zhengmin; Feng, Baixiang; Ma, Wenjun

    2016-01-01

    Although the health effects of ambient ozone have been widely assessed, their tempo-spatial variations remain unclear. We selected 20 communities (ten each from southern and northern USA) based on the US National Morbidity, Mortality, and Air Pollution Study (NMMAPS) dataset. A generalized linear model (GLM) was used to estimate the season-specific association between each 10 ppb (lag0-2 day average) increment in daily 8 h maximum ozone concentration and mortality in every community. The results showed that in the southern communities, a 10 ppb increment in ozone was linked to an increment of mortality of -0.07%, -0.17%, 0.40% and 0.27% in spring, summer, autumn and winter, respectively. For the northern communities, the excess risks (ERs) were 0.74%, 1.21%, 0.52% and -0.65% in the spring, summer, autumn and winter seasons, respectively. City-specific ozone-related mortality effects were positively related with latitude, but negatively related with seasonal average temperature in the spring, summer and autumn seasons. However, a reverse relationship was found in the winter. We concluded that there were different seasonal patterns of ozone effects on mortality between southern and northern US communities. Latitude and seasonal average temperature were identified as modifiers of the ambient ozone-related mortality risks. PMID:27571094

  20. Asteltoxins from the Entomopathogenic Fungus Pochonia bulbillosa 8-H-28.

    PubMed

    Adachi, Hayamitsu; Doi, Hiroyasu; Kasahara, Yuichi; Sawa, Ryuichi; Nakajima, Kaori; Kubota, Yumiko; Hosokawa, Nobuo; Tateishi, Ken; Nomoto, Akio

    2015-07-24

    New asteltoxins C (3) and D (4) were found in the extract of the entomopathogenic fungus Pochonia bulbillosa 8-H-28. Compound 2, which was spectroscopically identical with the known asteltoxin B, was isolated, and structural analysis led to a revision of the structure of asteltoxin B. Compounds 2 and 4 have a novel tricyclic ring system connected to a dienyl α-pyrone structure. Compound 3 has a 2,8-dioxabicyclo[3.3.0]octane ring similar to that of asteltoxin (1). Compound 3 showed potent antiproliferative activity against NIAS-SL64 cells derived from the fat body of Spodoptera litura larvae, while 2 and 4 were inactive. PMID:26120875

  1. Global health benefits of mitigating ozone pollution with methane emission controls

    NASA Astrophysics Data System (ADS)

    West, J. Jason; Fiore, Arlene M.; Horowitz, Larry W.; Mauzerall, Denise L.

    2006-03-01

    Methane (CH4) contributes to the growing global background concentration of tropospheric ozone (O3), an air pollutant associated with premature mortality. Methane and ozone are also important greenhouse gases. Reducing methane emissions therefore decreases surface ozone everywhere while slowing climate warming, but although methane mitigation has been considered to address climate change, it has not for air quality. Here we show that global decreases in surface ozone concentrations, due to methane mitigation, result in substantial and widespread decreases in premature human mortality. Reducing global anthropogenic methane emissions by 20% beginning in 2010 would decrease the average daily maximum 8-h surface ozone by 1 part per billion by volume globally. By using epidemiologic ozone-mortality relationships, this ozone reduction is estimated to prevent 30,000 premature all-cause mortalities globally in 2030, and 370,000 between 2010 and 2030. If only cardiovascular and respiratory mortalities are considered, 17,000 global mortalities can be avoided in 2030. The marginal cost-effectiveness of this 20% methane reduction is estimated to be 420,000 per avoided mortality. If avoided mortalities are valued at 1 million each, the benefit is 240 per tonne of CH4 (12 per tonne of CO2 equivalent), which exceeds the marginal cost of the methane reduction. These estimated air pollution ancillary benefits of climate-motivated methane emission reductions are comparable with those estimated previously for CO2. Methane mitigation offers a unique opportunity to improve air quality globally and can be a cost-effective component of international ozone management, bringing multiple benefits for air quality, public health, agriculture, climate, and energy. human health | mortality | tropospheric ozone | air quality


  2. Atmospheric characteristics conducive to high-ozone days in the Atlanta metropolitan area

    NASA Astrophysics Data System (ADS)

    Diem, Jeremy E.

    The purpose of this paper is to identify the atmospheric conditions associated with elevated ground-level ozone concentrations during June-August of 2000-2007 at 11 ozone-monitoring stations in the Atlanta, GA, USA metropolitan statistical area (MSA). Analyses were confined to high-ozone days (HODs), which had a daily maximum 8-h average ozone concentration in the 95th percentile of all June-August values. Therefore, each station had 36 HODs. The southeastern and far northern portions of the MSA had HODs with the highest and lowest ozone concentrations, respectively. HODs at nearly all Atlanta MSA ozone-monitoring stations were enabled by migratory anticyclones. HODs for most stations were hot, dry, and calm with low morning mixing heights and high afternoon mixing heights. All sets of HODs had daily mean relative humidities and afternoon mixing heights that, respectively, were significantly less than and significantly greater than mean values for the remaining days. Urbanized Atlanta typically was upwind of an ozone-monitoring station on its HODs; therefore, wind direction on HODs varied considerably among the stations. HODs may have been caused partially by NO x emissions from electric-utility power plants: HODs in the southern portion of the MSA were linked to air-parcel trajectories intersecting a power plant slightly northwest of Atlanta and plants in the Ohio River Valley, while HODs in the northern portion of the MSA were linked to air-parcel trajectories intersecting two large power plants slightly southeast of the Atlanta MSA. Results from this study suggest that future research in the Atlanta MSA should focus on power-plant contributions to ground-level ozone concentrations as well as the identification of non-monitored locations with potentially high ozone concentrations.

  3. Application of dynamic linear regression to improve the skill of ensemble-based deterministic ozone forecasts

    SciTech Connect

    Pagowski, M O; Grell, G A; Devenyi, D; Peckham, S E; McKeen, S A; Gong, W; Monache, L D; McHenry, J N; McQueen, J; Lee, P

    2006-02-02

    Forecasts from seven air quality models and surface ozone data collected over the eastern USA and southern Canada during July and August 2004 provide a unique opportunity to assess benefits of ensemble-based ozone forecasting and devise methods to improve ozone forecasts. In this investigation, past forecasts from the ensemble of models and hourly surface ozone measurements at over 350 sites are used to issue deterministic 24-h forecasts using a method based on dynamic linear regression. Forecasts of hourly ozone concentrations as well as maximum daily 8-h and 1-h averaged concentrations are considered. It is shown that the forecasts issued with the application of this method have reduced bias and root mean square error and better overall performance scores than any of the ensemble members and the ensemble average. Performance of the method is similar to another method based on linear regression described previously by Pagowski et al., but unlike the latter, the current method does not require measurements from multiple monitors since it operates on individual time series. Improvement in the forecasts can be easily implemented and requires minimal computational cost.

  4. Bayesian Maximum Entropy Integration of Ozone Observations and Model Predictions: A National Application.

    PubMed

    Xu, Yadong; Serre, Marc L; Reyes, Jeanette; Vizuete, William

    2016-04-19

    To improve ozone exposure estimates for ambient concentrations at a national scale, we introduce our novel Regionalized Air Quality Model Performance (RAMP) approach to integrate chemical transport model (CTM) predictions with the available ozone observations using the Bayesian Maximum Entropy (BME) framework. The framework models the nonlinear and nonhomoscedastic relation between air pollution observations and CTM predictions and for the first time accounts for variability in CTM model performance. A validation analysis using only noncollocated data outside of a validation radius rv was performed and the R(2) between observations and re-estimated values for two daily metrics, the daily maximum 8-h average (DM8A) and the daily 24-h average (D24A) ozone concentrations, were obtained with the OBS scenario using ozone observations only in contrast with the RAMP and a Constant Air Quality Model Performance (CAMP) scenarios. We show that, by accounting for the spatial and temporal variability in model performance, our novel RAMP approach is able to extract more information in terms of R(2) increase percentage, with over 12 times for the DM8A and over 3.5 times for the D24A ozone concentrations, from CTM predictions than the CAMP approach assuming that model performance does not change across space and time. PMID:26998937

  5. Effects of stratospheric ozone recovery on photochemistry and ozone air quality in the troposphere

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Wu, S.; Huang, Y.; Wang, Y.

    2014-04-01

    There has been significant stratospheric ozone depletion since the late 1970s due to ozone-depleting substances (ODSs). With the implementation of the Montreal Protocol and its amendments and adjustments, stratospheric ozone is expected to recover towards its pre-1980 level in the coming decades. In this study, we examine the implications of stratospheric ozone recovery for the tropospheric chemistry and ozone air quality with a global chemical transport model (GEOS-Chem). With a full recovery of the stratospheric ozone, the projected increases in ozone column range from 1% over the low latitudes to more than 10% over the polar regions. The sensitivity factor of troposphere ozone photolysis rate, defined as the percentage changes in surface ozone photolysis rate for 1% increase in stratospheric ozone column, shows significant seasonal variation but is always negative with absolute value larger than one. The expected stratospheric ozone recovery is found to affect the tropospheric ozone destruction rates much more than the ozone production rates. Significant decreases in surface ozone photolysis rates due to stratospheric ozone recovery are simulated. The global average tropospheric OH decreases by 1.7%, and the global average lifetime of tropospheric ozone increases by 1.5%. The perturbations to tropospheric ozone and surface ozone show large seasonal and spatial variations. General increases in surface ozone are calculated for each season, with increases by up to 0.8 ppbv in the remote areas. Increases in ozone lifetime by up to 13% are found in the troposphere. The increased lifetimes of tropospheric ozone in response to stratospheric ozone recovery enhance the intercontinental transport of ozone and global pollution, in particular for the summertime. The global background ozone attributable to Asian emissions is calculated to increase by up to 15% or 0.3 ppbv in the Northern Hemisphere in response to the projected stratospheric ozone recovery.

  6. Impact of increasing heat waves on U.S. ozone episodes in the 2050s: Results from a multimodel analysis using extreme value theory

    NASA Astrophysics Data System (ADS)

    Shen, L.; Mickley, L. J.; Gilleland, E.

    2016-04-01

    We develop a statistical model using extreme value theory to estimate the 2000-2050 changes in ozone episodes across the United States. We model the relationships between daily maximum temperature (Tmax) and maximum daily 8 h average (MDA8) ozone in May-September over 2003-2012 using a Point Process (PP) model. At ~20% of the sites, a marked decrease in the ozone-temperature slope occurs at high temperatures, defined as ozone suppression. The PP model sometimes fails to capture ozone-Tmax relationships, so we refit the ozone-Tmax slope using logistic regression and a generalized Pareto distribution model. We then apply the resulting hybrid-extreme value theory model to projections of Tmax from an ensemble of downscaled climate models. Assuming constant anthropogenic emissions at the present level, we find an average increase of 2.3 d a-1 in ozone episodes (>75 ppbv) across the United States by the 2050s, with a change of +3-9 d a-1 at many sites.

  7. CMAQ predictions of tropospheric ozone in the U.S. southwest: influence of lateral boundary and synoptic conditions.

    PubMed

    Shi, Chune; Fernando, H J S; Hyde, Peter

    2012-02-01

    Phoenix, Arizona, has been an ozone nonattainment area for the past several years and it remains so. Mitigation strategies call for improved modeling methodologies as well as understanding of ozone formation and destruction mechanisms during seasons of high ozone events. To this end, the efficacy of lateral boundary conditions (LBCs) based on satellite measurements (adjusted-LBCs) was investigated, vis-à-vis the default-LBCs, for improving the predictions of Models-3/CMAQ photochemical air quality modeling system. The model evaluations were conducted using hourly ground-level ozone and NO(2) concentrations as well as tropospheric NO(2) columns and ozone concentrations in the middle to upper troposphere, with the 'design' periods being June and July of 2006. Both included high ozone episodes, but the June (pre-monsoon) period was characterized by local thermal circulation whereas the July (monsoon) period by synoptic influence. Overall, improved simulations were noted for adjusted-LBC runs for ozone concentrations both at the ground-level and in the middle to upper troposphere, based on EPA-recommended model performance metrics. The probability of detection (POD) of ozone exceedances (>75ppb, 8-h averages) for the entire domain increased from 20.8% for the default-LBC run to 33.7% for the adjusted-LBC run. A process analysis of modeling results revealed that ozone within PBL during bulk of the pre-monsoon season is contributed by local photochemistry and vertical advection, while the contributions of horizontal and vertical advections are comparable in the monsoon season. The process analysis with adjusted-LBC runs confirms the contributions of vertical advection to episodic high ozone days, and hence elucidates the importance of improving predictability of upper levels with improved LBCs. PMID:22227303

  8. Ozonation of Canadian Athabasca asphaltene

    NASA Astrophysics Data System (ADS)

    Cha, Zhixiong

    Application of ozonation in the petrochemical industry for heavy hydrocarbon upgrading has not been sufficiently explored. Among heavy hydrocarbons, asphaltenes are the heaviest and the most difficult fractions for analysis and treatment. Therefore, ozonation of asphaltenes presents an interesting application in the petrochemical industry. Commercial application of ozonation in the petrochemical industry has three obstacles: availability of an ozone-resistant and environmentally friendly solvent, the precipitation of ozonation intermediates during reaction, and recovery of the solvent and separation of the ozonation products. Preliminary ozonation of Athabasca oil sands asphaltene in nonparticipating solvents encountered serious precipitation of the ozonation intermediates. The precipitated intermediates could be polymeric ozonides and intermolecular ozonides or polymeric peroxides. Because the inhomogeneous reaction medium caused low ozone efficiency, various participating solvents such as methanol and acetic acid were added to form more soluble hydroperoxides. The mass balance results showed that on average, one asphaltene molecule reacted with 12 ozone molecules through the electrophilic reaction and the subsequent decomposition of ozonation intermediates generated acetone extractable products. GC/MS analysis of these compounds indicated that the free radical reactions could be important for generation of volatile products. The extensively ozonated asphaltene in the presence of participating solvents were refluxed with methanol to generate more volatile products. GC/MS analysis of the methanol-esterified ozonation products indicated that most volatile products were aliphatic carboxylic acid esters generated through cleavage of substituents. Reaction kinetics study showed that asphaltene ozonation was initially a diffusion rate-controlled reaction and later developed to a chemical reaction rate-controlled reaction after depletion of the reactive aromatic sites

  9. Unequivocal detection of ozone recovery in the Antarctic Ozone Hole through significant increases in atmospheric layers with minimum ozone

    NASA Astrophysics Data System (ADS)

    de Laat, Jos; van Weele, Michiel; van der A, Ronald

    2015-04-01

    An important new landmark in present day ozone research is presented through MLS satellite observations of significant ozone increases during the ozone hole season that are attributed unequivocally to declining ozone depleting substances. For many decades the Antarctic ozone hole has been the prime example of both the detrimental effects of human activities on our environment as well as how to construct effective and successful environmental policies. Nowadays atmospheric concentrations of ozone depleting substances are on the decline and first signs of recovery of stratospheric ozone and ozone in the Antarctic ozone hole have been observed. The claimed detection of significant recovery, however, is still subject of debate. In this talk we will discuss first current uncertainties in the assessment of ozone recovery in the Antarctic ozone hole by using multi-variate regression methods, and, secondly present an alternative approach to identify ozone hole recovery unequivocally. Even though multi-variate regression methods help to reduce uncertainties in estimates of ozone recovery, great care has to be taken in their application due to the existence of uncertainties and degrees of freedom in the choice of independent variables. We show that taking all uncertainties into account in the regressions the formal recovery of ozone in the Antarctic ozone hole cannot be established yet, though is likely before the end of the decade (before 2020). Rather than focusing on time and area averages of total ozone columns or ozone profiles, we argue that the time evolution of the probability distribution of vertically resolved ozone in the Antarctic ozone hole contains a better fingerprint for the detection of ozone recovery in the Antarctic ozone hole. The advantages of this method over more tradition methods of trend analyses based on spatio-temporal average ozone are discussed. The 10-year record of MLS satellite measurements of ozone in the Antarctic ozone hole shows a

  10. Measurements and modelling of ozone in the Mediterranean MBL: an investigation of the importance of ship emissions to local ozone production

    NASA Astrophysics Data System (ADS)

    Hedgecock, I. M.; Gencarelli, C. N.; Sch{ü}rmann, G. J.; Sprovieri, F.; Pirrone, N.

    2012-07-01

    Elevated concentrations of ground level ozone are both hazardous to human health and detrimental to agricultural production. The Mediterranean Basin, due to its position under the descending branch of the Hadley Cell circulation during the summer months, enjoys periods of stable, sunny and warm weather which provide ideal conditions for the production of ozone. The presence of major population centres and numerous industrialised areas in the coastal zone result in both a continual supply of ozone precursor compounds and also a significant number of people to suffer the consequences of high ozone concentrations. Using the WRF/Chem model validated with data obtained from seven oceanographic measurement campaigns, performed between 2000 and 2010, aboard the Italian Research Council's R. V. Urania, and also from a number of EMEP monitoring stations located around the Mediterranean Basin, the importance of emissions from maritime traffic in the region has been investigated. The model results indicate that over large areas of the Mediterranean emissions from shipping contribute between 5 and 10 ppb to the ground level O3 daily average concentration during the summer. The contribution to the hourly average O3 is up to 40 ppb in some particularly busy shipping lanes. Importantly the results suggest that in a number of coastal areas the contribution from ship emissions to the local O3 concentration can make the difference between complying with the EU Air Quality standard of a maximum 8 h mean of 120 μg m-3 and exceeding it.

  11. Ozone distributions over southern Lake Michigan: comparisons between ferry-based observations, shoreline-based DOAS observations and air quality forecast models

    NASA Astrophysics Data System (ADS)

    Cleary, P. A.; Fuhrman, N.; Schulz, L.; Schafer, J.; Fillingham, J.; Bootsma, H.; Langel, T.; Williams, E. J.; Brown, S. S.

    2014-09-01

    Air quality forecast models typically predict large ozone abundances over water relative to land in the Great Lakes region. While each state bordering Lake Michigan has dedicated monitoring systems, offshore measurements have been sparse, mainly executed through specific short-term campaigns. This study examines ozone abundances over Lake Michigan as measured on the Lake Express ferry, by shoreline Differential Optical Absorption Spectroscopy (DOAS) observations in southeastern Wisconsin, and as predicted by the National Air Quality Forecast System. From 2008-2009 measurements of O3, SO2, NO2 and formaldehyde were made in the summertime by DOAS at a shoreline site in Kenosha, WI. From 2008-2010 measurements of ambient ozone conducted on the Lake Express, a high-speed ferry that travels between Milwaukee, WI and Muskegon, MI up to 6 times daily from spring to fall. Ferry ozone observations over Lake Michigan were an average of 3.8 ppb higher than those measured at shoreline in Kenosha with little dependence on position of the ferry or temperature but with highest differences during evening and night. Concurrent ozone forecast images from National Weather System's National Air Quality Forecast System in the upper Midwestern region surrounding Lake Michigan were saved over the ferry ozone sampling period in 2009. The bias of the model O3 forecast was computed and evaluated with respect to ferry-based measurements. The model 1 and 8 h ozone mean biases were both 12 ppb higher than observed ozone, and maximum daily 1 h ozone mean bias was 10 ppb, indicating substantial ozone over-prediction over water. Trends in the bias with respect to location and time of day or month were also explored showing non-uniformity in model bias. Extreme ozone events were predicted by the model but not observed by ferry measurements.

  12. Tropospheric ozone in the vicinity of the ozone hole - 1987 Airborne Antarctic Ozone Experiment

    NASA Technical Reports Server (NTRS)

    Gregory, Gerald L.; Warren, Linda S.; Hypes, Warren D.; Tuck, Adrian F.; Kelly, Kenneth K.; Krueger, Arlin J.

    1989-01-01

    Results are presented on ozone measurements in the upper troposphere/lower stratosphere over Antarctica, obtained by NASA DC-8 aircraft during the August/September 1987 Airborne Antarctic Ozone Experiment. The ozone mixing ratios as high as several hundred ppbv were measured, but in all cases these ratios were observed in pockets of upper atmospheric air, both in the vicinity of and away from the location of the ozone hole. The background ozone values in the surrounding troposphere were typically in the range of 20-50 ppbv. Correlation of tropospheric ozone observations with the boundaries of the ozone hole differed in the course of the experiment. During the August 28 - September 2 flights, encounters with ozone-rich air were limited, and the background tropospheric ozone appeared to decrease beneath the hole. For the later flights, and as the ozone hole deepened, the ozone-rich air was frequently observed in the vicinity of the hole, and the average ozone values at the flight altitude were frequently higher than the background values.

  13. The Influence of European Pollution on Ozone in the Near East and Northern Africa

    NASA Technical Reports Server (NTRS)

    Duncan, B. N.; West, J. J.; Yoshida, Y.; Fiore, A. M.; Ziemke, J. R.

    2008-01-01

    We present a modeling study of the long-range transport of pollution from Europe, showing that European emissions regularly elevate surface ozone by as much as 20 ppbv in summer in northern Africa and the Near East. European emissions cause 50-150 additional violations per year (i.e. above those that would occur without European pollution) of the European health standard for ozone (8-h average greater than 120 micrograms per cubic meters or approximately 60 ppbv) in northern Africa and the Near East. We estimate that European ozone pollution is responsible for 50 000 premature mortalities globally each year, of which the majority occurs outside of Europe itself, including 37% (19 000) in northern Africa and the Near East. Much of the pollution from Europe is exported southward at low altitudes in summer to the Mediterranean Sea, northern Africa and the Near East, regions with favorable photochemical environments for ozone production. Our results suggest that assessments of the human health benefits of reducing ozone precursor emissions in Europe should include effects outside of Europe, and that comprehensive planning to improve air quality in northern Africa and the Near East likely needs to address European emissions.

  14. Tropospheric ozone in the vicinity of the ozone hole: 1987 Airborne Antarctic Ozone Experiment

    SciTech Connect

    Gregory, G.L.; Warren, L.S. ); Hypes, W.D. ); Tuck, A.F.; Kelly, K.K. ); Krueger, A.J. )

    1989-11-30

    Tropospheric ozone measurements over Antarctica aboard the NASA DC-8 aircraft are summarized. As part of the August/September 1987 Airborne Antarctic Ozone Experiment, the aircraft flew 13 missions covering a latitude of 53{degree}-90{degree}S, at altitudes to 13 km. Ozone mixing ratios as high as several hundred parts per billion by volume (ppbv) were measured, but in all cases these ratios were observed in pockets or patches of upper atmospheric air. These pockets were observed both in the vicinity of and away from the location of the ozone hole. At times, and as a result of these pockets, the ozone levels at the flight altitude of the aircraft, as averaged beneath the boundaries of the stratospheric ozone hole, were 2-3 times higher than background tropospheric values. The data suggest that the ozone-rich air seldom penetrated below about 9-km altitude. Background ozone values in the surrounding troposphere were typically in the range of 20-50 ppbv. Correlation of tropospheric ozone observations with the boundaries of the ozone hole differed during the experiment. During the early flights (August 28 through September 2), encounters with ozone-rich air were limited and background tropospheric ozone (at the flight altitude) appeared to decrease beneath the hole. For many of the later flights, and as the hole deepened, the reverse was noted, in that ozone-rich air was frequently observed in the vicinity of the hole and, as noted earlier, average ozone at the flight altitude was frequently higher than background values.

  15. Surface ozone in the Lake Tahoe Basin

    NASA Astrophysics Data System (ADS)

    Burley, Joel D.; Theiss, Sandra; Bytnerowicz, Andrzej; Gertler, Alan; Schilling, Susan; Zielinska, Barbara

    2015-05-01

    Surface ozone (O3) concentrations were measured in and around the Lake Tahoe Basin using both active monitors (2010) and passive samplers (2002, 2010). The 2010 data from active monitors indicate average summertime diurnal maxima of approximately 50-55 ppb. Some site-to-site variability is observed within the Basin during the well-mixed hours of 10:00 to 17:00 PST, but large differences between different sites are observed in the late evening and pre-dawn hours. The observed trends correlate most strongly with elevation, topography, and surface vegetation. High elevation sites with steeply sloped topography and drier ground cover experience elevated O3 concentrations throughout the night because they maintain good access to downward mixing of O3-rich air from aloft with smaller losses due to dry deposition. Low elevation sites with flat topography and more dense surface vegetation experience low O3 concentrations in the pre-dawn hours because of greatly reduced downward mixing coupled with enhanced O3 removal via efficient dry deposition. Additionally, very high average O3 concentrations were measured with passive samplers in the middle of the Lake in 2010. This latter result likely reflects diminished dry deposition to the surface of the Lake. High elevation Tahoe Basin sites with exposure to nocturnal O3-rich air from aloft experience daily maxima of 8-h average O3 concentrations that are frequently higher than concurrent maxima from the polluted upwind comparison sites of Sacramento, Folsom, and Placerville. Wind rose analyses of archived NAM 12 km meteorological data for the summer of 2010 suggest that some of the sampling sites situated near the shoreline may have experienced on-shore "lake breezes" during daytime hours and/or off-shore "land breezes" during the night. Back-trajectory analysis with the HYSPLIT model suggests that much of the ozone measured at Lake Tahoe results from the transport of "polluted background" air into the Basin from upwind

  16. Table Mountain ozone intercomparison: Brewer ozone spectrophotometer Umkehr observations

    SciTech Connect

    McElroy, C.T.; Kerr, J.B.

    1995-05-20

    The authors present the result of ozone column measurements, and vertical profiles, derived from Brewer ozone spectrophotometer measurements, in conjunction with the Umkehr technique. The Umkehr results agreed within 15% with the average measurments of this campaign between 20 and 40 km altitude. When restricted to the altitude range of 24 to 40 km the agreement was within about 5%.

  17. Nqrs Data for C8H9KO6 [C8H5KO4·2(H2O)] (Subst. No. 1092)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H9KO6 [C8H5KO4·2(H2O)] (Subst. No. 1092)

  18. KINETICS MODEL AND OZONE ISOPLETH PLOTTING PACKAGE

    EPA Science Inventory

    The Kinetics Model and Ozone Isopleth Plotting Package (OZIPP) computer program can be used to simulate ozone formation in urban atmospheres. OZIPP calculates maximum one-hour average ozone concentrations given a set of input assumptions about initial precursor concentrations, li...

  19. Quaternion Averaging

    NASA Technical Reports Server (NTRS)

    Markley, F. Landis; Cheng, Yang; Crassidis, John L.; Oshman, Yaakov

    2007-01-01

    Many applications require an algorithm that averages quaternions in an optimal manner. For example, when combining the quaternion outputs of multiple star trackers having this output capability, it is desirable to properly average the quaternions without recomputing the attitude from the the raw star tracker data. Other applications requiring some sort of optimal quaternion averaging include particle filtering and multiple-model adaptive estimation, where weighted quaternions are used to determine the quaternion estimate. For spacecraft attitude estimation applications, derives an optimal averaging scheme to compute the average of a set of weighted attitude matrices using the singular value decomposition method. Focusing on a 4-dimensional quaternion Gaussian distribution on the unit hypersphere, provides an approach to computing the average quaternion by minimizing a quaternion cost function that is equivalent to the attitude matrix cost function Motivated by and extending its results, this Note derives an algorithm that deterniines an optimal average quaternion from a set of scalar- or matrix-weighted quaternions. Rirthermore, a sufficient condition for the uniqueness of the average quaternion, and the equivalence of the mininiization problem, stated herein, to maximum likelihood estimation, are shown.

  20. Calculations of Polar Ozone Loss Rates

    NASA Technical Reports Server (NTRS)

    Dessler, A. E.; Wu, J.

    1999-01-01

    We calculate vortex-averaged ozone loss rates at 465-K potential temperature during the Aug.-Sept. time period in the southern hemisphere and Feb.-Mar. time period in the northern hemisphere. Ozone loss rates are calculated two ways. First, from the time series of measurements of 03. Second, from measurements of ClO, from which ozone loss is inferred based on our theories of Cl-catalyzed ozone destruction. Both measurement sets are from the Upper Atmosphere Research Satellite (UARS) Microwave Limb Sounder (MLS) instrument. We find good agreement between vortex-averaged ozone loss rates calculated from these methods. Our analysis provides no support for recent work suggesting that current theories of Cl-catalyzed ozone loss underestimate the observed decrease in polar ozone during the ozone "hole" period.

  1. Influence of synoptic patterns on surface ozone variability over the Eastern United States from 1980 to 2012

    NASA Astrophysics Data System (ADS)

    Shen, L.; Mickley, L. J.; Tai, A. P. K.

    2015-05-01

    We investigate the effect of synoptic-scale weather patterns on observed maximum daily 8 h average (MDA8) surface ozone over the eastern United States during 1980-2012 in summer (June-August, JJA). Zonally averaged, the SD of daily MDA8 JJA ozone shows a bimodal structure, with peaks at 30-35° N and 39-43° N, identifying those regions most influenced by daily weather variability. We apply Empirical Orthogonal Functions (EOFs) to understand the causes of this structure. The first three leading EOF patterns explain 53% of the total variance in deseasonalized surface ozone, displaying (1) a widespread decrease of ozone in the eastern United States associated with southward movement of jet wind, (2) a north-south pattern linked to the Bermuda High system when its west boundary is located along the East coast, and (3) an east-west pattern characteristic of a westward extension of Bermuda High and an enhanced Great Plains low level jet (GPLLJ). The northern peak of ozone SD can be explained by polar jet activity, while the southern peak appears related to variability in the Bermuda High and GPLLJ. In the Midwest and Northeast, we find that the correlation coefficient r between detrended mean JJA MDA8 ozone and the polar jet frequency ranges between -0.76 and -0.93 over 1980-2012 depending on the time period selected, suggesting that polar jet frequency could provide a simple metric to predict ozone variability in future climate regimes. In the Southeast, the influence of the Bermuda High on mean JJA MDA8 ozone depends on the location of its west edge. For those summers when the average position of the west edge is located west of ∼ 85.4° W, a westward shift in the Bermuda High west edge increases ozone in the Southeast by ∼ 1 ppbv deg-1 in longitude. For all summers, a northward shift in the Bermuda High west edge increases ozone over the entire eastern United States by 1-2 ppbv deg-1 in latitude. None of the synoptic patterns identified in this study show a

  2. Solving the Tulsa ozone problem

    SciTech Connect

    Wagner, K.K.; Wilson, J.D.; Gibeau, E.

    1998-12-31

    Local governments and interested parties in Tulsa, Oklahoma are planning actions to keep Tulsa in compliance with the ozone ambient air quality standard. Based on recent data Tulsa exceeds the new eight hour average national ambient air quality standard for ozone and occasionally exceeds the previous one hour standard. Currently, Tulsa is in attainment of the former one-hour ozone standard. The first planning step is to integrate the existing information about Tulsa`s ozone problem. Prior studies of Tulsa ozone are reviewed. Tulsa`s recent air quality and meteorological monitoring are evaluated. Emission inventory estimates are assessed. Factors identified with Tulsa`s ozone problem are the transport of ozone and precursor gases, a possible role for biogenic emissions, and a simplistic ozone forecasting method. The integration of information found that current air quality and meteorological monitoring is meager. Observations of volatile organic compounds and NO{sub y} are absent. Prior intensive studies in 1977 and 1985 are more than ten years old and lack relevance to today`s problem. Emission inventory estimates are scarce and uncertain. The current knowledge base was judged inadequate to properly characterize the present ozone problem. Actions are recommended to enlarge the information base to address Tulsa`s ozone problem.

  3. The 1990 Antarctica ozone hole as observed by TOMS. [Total Ozone Mapping Spectrometer

    NASA Technical Reports Server (NTRS)

    Newman, Paul; Stolarski, Richard; Schoeberl, Mark; Mcpeters, Richard; Krueger, Arlin

    1991-01-01

    The 1990 Antarctic ozone hole matched the record 1987 ozone hole in depth, duration, and area. During the formation phase of the hole (August), total ozone values were the lowest yet recorded. The decline rate approximately matched the record 1987 decline and reached a minimum of 125 Dobson Units on October 4, 1990. October total ozone averages were marginally higher that 1987. As during 1987, the 1990 total ozone values within the hole slowly and steadily increased during the mid-October through November period. The ozone hole breakup was the latest yet recorded (early December), with low ozone values persisting over the pole through December, setting a record low for December average polar ozone. Temperatures were near average during the early spring, but were below normal for the late spring. Temperatures in the early spring of 1990 were substantially warmer than those observed in the early spring of 1987.

  4. The 1990 Antarctic ozone hole as observed by TOMS. [Total Ozone Mapping Spectrometer

    SciTech Connect

    Newman, P.; Stolarski, R.; Schoeberl, M.; McPeters, R.; Krueger, A.

    1991-04-01

    The 1990 Antarctic ozone hole matched the record 1987 ozone hole in depth, duration, and area. During the formation phase of the hole (August), total ozone values were the lowest yet recorded. The decline rate approximately matched the record 1987 decline, and reached a minimum of 125 Dobson Units on October 4, 1990. October total ozone averages were marginally higher than 1987. As during 1987, the 1990 total ozone values within the hole slowly and steadily increased during the mid-October through November period. The ozone hole breakup was the latest yet recorded (early December), with low ozone values persisting over the pole through December, setting a record low for December average polar ozone. Temperatures were near average during the early spring, but were below normal for the late-spring. Temperatures in the early spring of 1990 were substantially warmer than those observed in the early spring of 1987.

  5. Atmospheric conditions associated with high and low summertime ozone levels in the boundary layer over some eastern Mediterranean airports

    NASA Astrophysics Data System (ADS)

    Kalabokas, Pavlos D.; Thouret, Valerie; Cammas, Jean-Pierre; Volz-Thomas, Andreas; Boulanger, Damien; Repapis, Christos C.

    2013-04-01

    Thanks to the vertical atmospheric measurements of the MOZAIC program, enhanced ozone mixing ratios in the lower troposphere over the Eastern Mediterranean have been found, frequently exceeding the 60 ppb, 8-h EU air quality standard, whereas ozone between 700 hPa and 400 hPa was only slightly (3-5 ppb, 5-10%) higher than over Central Europe. Also, the examination of the highest and lowest ozone levels in the lower troposphere (1.5-5 km) over some airports in the Eastern Mediterranean area showed the lower-tropospheric ozone variability over there is controlled mainly by the synoptic meteorological conditions, combined with local topographical and meteorological features. In particular, the highest ozone concentrations in the lower troposphere and subsequently in the boundary layer in the area are associated with large scale subsidence of ozone rich air masses from the upper troposphere under anticyclonic conditions while the lowest ozone concentrations are associated with low pressure conditions inducing uplifting of boundary layer air, poor in ozone and rich in relative humidity, to the lower troposphere. In order to further evaluate the observed high rural ozone levels during summertime, vertical summer ozone profiles measured by MOZAIC in the period 1994-2008 over the Eastern Mediterranean basin (Cairo, Tel-Aviv, Heraklion, Rhodes, Antalya) are analyzed, focusing in the boundary layer (0-1.5 km). First, vertical profiles collected during extreme days with very high or very low tropospheric ozone mixing ratios are examined. Also, the average profiles of ozone, relative humidity, carbon monoxide, vertical temperature gradient and wind speed corresponding to the 7% highest and the 7% lowest ozone mixing ratios for the height layers of 0-500m, 500-1000m and 1000-1500m for Cairo and Tel-Aviv are examined along with the corresponding composite maps of geopotential heights at 850 hPa and 925 hPa. In addition, analyses of backward trajectories, using the FLEXPART model

  6. Regional ozone impacts of increased natural gas use in the Texas power sector and development in the Eagle Ford shale.

    PubMed

    Pacsi, Adam P; Kimura, Yosuke; McGaughey, Gary; McDonald-Buller, Elena C; Allen, David T

    2015-03-17

    The combined emissions and air quality impacts of electricity generation in the Texas grid and natural gas production in the Eagle Ford shale were estimated at various natural gas price points for the power sector. The increased use of natural gas in the power sector, in place of coal-fired power generation, drove reductions in average daily maximum 8 h ozone concentration of 0.6-1.3 ppb in northeastern Texas for a high ozone episode used in air quality planning. The associated increase in Eagle Ford upstream oil and gas production nitrogen oxide (NOx) emissions caused an estimated local increase, in south Texas, of 0.3-0.7 ppb in the same ozone metric. In addition, the potential ozone impacts of Eagle Ford emissions on nearby urban areas were estimated. On the basis of evidence from this work and a previous study on the Barnett shale, the combined ozone impact of increased natural gas development and use in the power sector is likely to vary regionally and must be analyzed on a case by case basis. PMID:25723953

  7. Protecting beans from ozone

    SciTech Connect

    Pierce, R.

    1983-03-01

    A chemical treatment to protect navy beans from ozone damage increased yields by an average of more than 20% in 3 years of tests. An experimental antioxidant chemical, EDU, made by the DuPont company was tested as soil applications and sprays on several varieties and under a variety of soil and planting conditions. The average yield increases were between 16 and 24%. Chemical treatment also increased snap bean pod production by 12%.

  8. Effects of plug-in hybrid electric vehicles on ozone concentrations in Colorado.

    PubMed

    Brinkman, Gregory L; Denholm, Paul; Hannigan, Michael P; Milford, Jana B

    2010-08-15

    This study explores how ozone concentrations in the Denver, CO area might have been different if plug-in hybrid electric vehicles (PHEVs) had replaced light duty gasoline vehicles in summer 2006. A unit commitment and dispatch model was used to estimate the charging patterns of PHEVs and dispatch power plants to meet electricity demand. Emission changes were estimated based on gasoline displacement and the emission characteristics of the power plants providing additional electricity. The Comprehensive Air Quality Model with extensions (CAMx) was used to simulate the effects of these emissions changes on ozone concentrations. Natural gas units provided most of the electricity used for charging PHEVs in the scenarios considered. With 100% PHEV penetration, nitrogen oxide (NO(x)) emissions were reduced by 27 tons per day (tpd) from a fleet of 1.7 million vehicles and were increased by 3 tpd from power plants; VOC emissions were reduced by 57 tpd. These emission changes reduced modeled peak 8-h average ozone concentrations by approximately 2-3 ppb on most days. Ozone concentration increases were modeled for small areas near central Denver. Future research is needed to forecast when significant PHEV penetration may occur and to anticipate characteristics of the corresponding power plant and vehicle fleets. PMID:20704224

  9. Recent Results of Ambient Ozone Monitoring in Southern Sierra Nevada and White Mountains, California

    NASA Astrophysics Data System (ADS)

    Burley, J. D.; Bytnerowicz, A.; Cisneros, R.; Schweizer, D.

    2014-12-01

    Ambient ozone has been monitored in the southern Sierra Nevada and White Mountains of California as 2-week average concentrations with Ogawa passive samplers and as 1-hour average concentrations with 2B Technologies UV absorption monitors. Our summer season investigations have included: (1) an elevational transect (1,237 to 4,342 masl) consisting of 5 sites in the White Mountains (2009 -2014); (2) a west to east southern Sierra Nevada transect consisting of 9 sites at elevations between 510 and 3,490 masl (2012 and 2013); and (3) two sites at the Devils Postpile National Monument at 2,130 masl (2007 - 2014). In the White Mountains average ozone concentrations increased with elevation, reaching the highest values at White Mountain Summit. A strongly pronounced diurnal distribution of ozone was observed at the low elevation site in Bishop (OVS), with low values at night and in the early morning and highest concentrations during mid-day. High elevation sites (Crooked Creek, Barcroft Station and Summit) were characterized by flat ozone curves with similar concentrations during daytime and nighttime, typically around 50 ppb. During the 2013 summer season, two-week averages from passive samplers ranged from 32 to 60 ppb for all White Mountains sites with the highest values at the Summit and the lowest at OVS. Along the southern Sierra Nevada transect, average concentrations in summer 2013 ranged from 36.5 to 54.0 ppb with the highest value recorded at the highest elevation eastern site, Piute Pass, and the lowest at low-elevation and western Shaver Lake site. Prather, Mountain Rest and Shaver Lake sites had the most exceedances of 8 h federal health standard of 75 ppb and the California health standard of 70 ppb. The Devils Postpile site was characterized by low ozone concentrations at night and in the early morning, and late afternoon maxima. In 2007 and 2008 the ozone values measured at Devils Postpile occasionally exceeded the federal health standard, with more

  10. Chemistry and Dynamics of the Unusual 2015 Antarctic Ozone Hole

    NASA Astrophysics Data System (ADS)

    Braathen, Geir O.

    2016-04-01

    The Global Atmosphere Watch of the World Meteorological Organization includes several stations in Antarctica that keep a close eye on the ozone layer during the ozone hole season. Observations made during the unusually large ozone hole of 2015 will be compared to ozone holes from 2003 to 2014 and interpreted in light of the meteorological conditions. Satellite observations will be used to get a more general picture of the size and depth of the ozone hole and will also be used to calculate various metrics for ozone hole severity. In 2003, 2005 and 2006, the ozone hole was relatively large with more ozone loss than normal. This is in particular the case for 2006, which by most ozone hole metrics was the most severe ozone hole on record. On the other hand, the ozone holes of 2004, 2007, 2010 and 2012, 2013 and 2014 were less severe than normal, and only the very special ozone hole of 2002 had less ozone depletion when one regards the ozone holes of the last decade. The South Polar vortex of 2015 was unusually stable and long-lived, so ozone depletion lasted longer than seen in recent years. The ozone hole area, i.e. the area where total ozone is less that 220 DU, averaged over the worst 60 consecutive days was larger in 2015 than in any other year since the beginning of the ozone hole era in the early 1980s.

  11. A total ozone-dependent ozone profile climatology based on ozonesondes and Aura MLS data

    NASA Astrophysics Data System (ADS)

    Labow, Gordon J.; Ziemke, Jerald R.; McPeters, Richard D.; Haffner, David P.; Bhartia, Pawan K.

    2015-03-01

    Ozone profiles measured with the Aura Microwave Limb Sounder (MLS) and ozonesondes are used to create a new ozone climatology that can be used for satellite retrievals and radiative transfer studies. The climatology is binned according to total column ozone amount and latitude rather than with season. Because of high correlation between ozone profile shape and total ozone, the ozone profiles in this climatology capture ozone variations well, especially near the tropopause. This climatology has been constructed from nearly a million individual MLS ozone profile measurements taken between 2004 and 2013 as well as over 55,000 ozonesonde measurements from 1988 to 2011. The MLS profiles were sorted by total column ozone as measured by Ozone Monitoring Instrument in observations that were coincident with the MLS measurements. The data from the sondes were used in the troposphere and lower stratosphere and MLS in the middle and upper stratosphere. These two data sets were blended together between 13 and 17 km (~159-88 hPa). This climatology consists of average ozone profiles as a function of total ozone for six 30° latitude bands covering altitudes between 0 and 75 km (in Z* pressure altitude coordinates) as well as the corresponding standard deviations for each layer. There is no seasonal component. This new climatology shows some remarkable and somewhat unexpected correlations between the total column ozone and the ozone amount at some layers, particularly in the lower and middle troposphere in some latitude bands.

  12. Polar ozone

    NASA Technical Reports Server (NTRS)

    Solomon, S.; Grose, W. L.; Jones, R. L.; Mccormick, M. P.; Molina, Mario J.; Oneill, A.; Poole, L. R.; Shine, K. P.; Plumb, R. A.; Pope, V.

    1990-01-01

    The observation and interpretation of a large, unexpected ozone depletion over Antarctica has changed the international scientific view of stratospheric chemistry. The observations which show the veracity, seasonal nature, and vertical structure of the Antarctic ozone hole are presented. Evidence for Arctic and midlatitude ozone loss is also discussed. The chemical theory for Antarctic ozone depletion centers around the occurrence of polar stratospheric clouds (PSCs) in Antarctic winter and spring; the climatology and radiative properties of these clouds are presented. Lab studies of the physical properties of PSCs and the chemical processes that subsequently influence ozone depletion are discussed. Observations and interpretation of the chemical composition of the Antarctic stratosphere are described. It is shown that the observed, greatly enhanced abundances of chlorine monoxide in the lower stratosphere are sufficient to explain much if not all of the ozone decrease. The dynamic meteorology of both polar regions is given, interannual and interhemispheric variations in dynamical processes are outlined, and their likely roles in ozone loss are discussed.

  13. Ozone decomposition

    PubMed Central

    Batakliev, Todor; Georgiev, Vladimir; Anachkov, Metody; Rakovsky, Slavcho

    2014-01-01

    Catalytic ozone decomposition is of great significance because ozone is a toxic substance commonly found or generated in human environments (aircraft cabins, offices with photocopiers, laser printers, sterilizers). Considerable work has been done on ozone decomposition reported in the literature. This review provides a comprehensive summary of the literature, concentrating on analysis of the physico-chemical properties, synthesis and catalytic decomposition of ozone. This is supplemented by a review on kinetics and catalyst characterization which ties together the previously reported results. Noble metals and oxides of transition metals have been found to be the most active substances for ozone decomposition. The high price of precious metals stimulated the use of metal oxide catalysts and particularly the catalysts based on manganese oxide. It has been determined that the kinetics of ozone decomposition is of first order importance. A mechanism of the reaction of catalytic ozone decomposition is discussed, based on detailed spectroscopic investigations of the catalytic surface, showing the existence of peroxide and superoxide surface intermediates. PMID:26109880

  14. Ozone decomposition.

    PubMed

    Batakliev, Todor; Georgiev, Vladimir; Anachkov, Metody; Rakovsky, Slavcho; Zaikov, Gennadi E

    2014-06-01

    Catalytic ozone decomposition is of great significance because ozone is a toxic substance commonly found or generated in human environments (aircraft cabins, offices with photocopiers, laser printers, sterilizers). Considerable work has been done on ozone decomposition reported in the literature. This review provides a comprehensive summary of the literature, concentrating on analysis of the physico-chemical properties, synthesis and catalytic decomposition of ozone. This is supplemented by a review on kinetics and catalyst characterization which ties together the previously reported results. Noble metals and oxides of transition metals have been found to be the most active substances for ozone decomposition. The high price of precious metals stimulated the use of metal oxide catalysts and particularly the catalysts based on manganese oxide. It has been determined that the kinetics of ozone decomposition is of first order importance. A mechanism of the reaction of catalytic ozone decomposition is discussed, based on detailed spectroscopic investigations of the catalytic surface, showing the existence of peroxide and superoxide surface intermediates. PMID:26109880

  15. Monsoon circulation and atmospheric ozone

    NASA Astrophysics Data System (ADS)

    Khrgian, A. Kh.; Nguyen, Van Thang

    1991-01-01

    The effect of the Indonesian-Australian winter monsoon, proceeding from the Asian continent to the south, on the atmospheric ozone is examined. It is shown that large-scale atmospheric circulation phenomena caused by monsoons in the tropical regions of Australia and in south-eastern Asia can cause significant falls in atmospheric ozone concentrations. The common occurrence of such phenomena might explain the higher-than-average incidence of skin cancer in Australia.

  16. Ozone variability

    NASA Astrophysics Data System (ADS)

    Duetsch, H. U.

    1983-09-01

    The annual and long-term variations in the atmospheric ozone layer were examined on the basis of 55 yr of data taken at Aroya, Switzerland and 25 yr of data gathered by the global ozone network. Attention was given to annual and biennial variations, which showed that the midlatitude peak concentration was affected by a quasi-biennial variation of the tropical stratospheric circulation. Smaller scale circulation patterns were dominant in the lower stratosphere, although an observed negative trend of the total ozone was equally distributed between the troposphere and 24 km altitude. The global ozone increase detected in the 1960s was possible due to general circulation alterations, but may also have been influenced by injection of NO(x) into the atmosphere during atomic bomb testing.

  17. Ozone, Tropospheric

    NASA Technical Reports Server (NTRS)

    Fishman, Jack

    1995-01-01

    In the early part of the 20th century, ground-based and balloon-borne measurements discovered that most of atmosphere's ozone is located in the stratosphere with highest concentrations located between 15 and 30 km (9,3 and 18.6 miles). For a long time, it was believed that tropospheric ozone originated from the stratosphere and that most of it was destroyed by contact with the earth's surface. Ozone, O3, was known to be produced by the photo-dissociation of molecular oxygen, O2, a process that can only occur at wavelengths shorter than 242 nm. Because such short-wave-length radiation is present only in the stratosphere, no tropospheric ozone production is possible by this mechanism. In the 1940s, however, it became obvious that production of ozone was also taking place in the troposphere. The overall reaction mechanism was eventually identified by Arie Haagen-Smit of the California Institute of Technology, in highly polluted southern California. The copious emissions from the numerous cars driven there as a result of the mass migration to Los Angeles after World War 2 created the new unpleasant phenomenon of photochemical smog, the primary component of which is ozone. These high levels of ozone were injuring vegetable crops, causing women's nylons to run, and generating increasing respiratory and eye-irritation problems for the populace. Our knowledge of tropospheric ozone increased dramatically in the early 1950s as monitoring stations and search centers were established throughout southern California to see what could be done to combat this threat to human health and the environment.

  18. Options to accelerate ozone recovery: ozone and climate benefits

    NASA Astrophysics Data System (ADS)

    Daniel, J. S.; Fleming, E. L.; Portmann, R. W.; Velders, G. J. M.; Jackman, C. H.; Ravishankara, A. R.

    2010-08-01

    Hypothetical reductions in future emissions of ozone-depleting substances (ODSs) and N2O are evaluated in terms of effects on equivalent effective stratospheric chlorine (EESC), globally-averaged total column ozone, and radiative forcing through 2100. Due to the established success of the Montreal Protocol, these actions can have only a fraction of the impact on ozone depletion that regulations already in force have had. If all anthropogenic ODS and N2O emissions were halted beginning in 2011, ozone is calculated to be higher by about 1-2% during the period 2030-2100 compared to a case of no additional restrictions. Direct radiative forcing by 2100 would be about 0.23 W/m2 lower from the elimination of anthropogenic N2O emissions and about 0.005 W/m2 lower from the destruction of the chlorofluorocarbon (CFC) bank. Due to the potential impact of N2O on future ozone levels, we provide an approach to incorporate it into the EESC formulation, which is used extensively in ozone depletion analyses. The ability of EESC to describe total ozone changes arising from additional ODS and N2O controls is also quantified.

  19. Trends in ozone profile measurements

    NASA Technical Reports Server (NTRS)

    Johnston, H.; Aikin, A.; Barnes, R.; Chandra, S.; Cunnold, D.; Deluisi, J.; Gille, J. C.; Hudson, R.; Mccormick, M. P.; Mcmaster, L.

    1989-01-01

    From an examination of the agreements and differences between different satellite instruments, it is difficult to believe that existing satellite instruments determine upper stratospheric ozone much better than 4 pct.; by extension, it probably would require at least a 4 pct. change to be reliably detected as a change. The best estimates of the vertical profiles of ozone change in the upper stratosphere between 1979 and 1986 are judged to be those given by the two SAGE satellite instruments. SAGE-2 minus SAGE-1 gives a much lower ozone reduction than that given by the archived Solar Backscatter UV data. The average SAGE profiles of ozone changes between 20 and 50 degs north and between 20 and 50 degs south are given. The SAGE-1 and SAGE-2 comparison gives an ozone reduction of about 4 pct. at 25 km over temperate latitudes. Five ground based Umkehr stations between 36 and 52 degs north, corrected for the effects of volcanic aerosols, report an ozone reduction between 1979 and 1987 at Umkehr layer 8 of 9 + or - 5 pct. The central estimate of upper stratospheric ozone reduction given by SAGE at 40 km is less than the central value estimated by the Umkehr method at layer 8.

  20. NQRS Data for C8H9DO (Subst. No. 1091)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H9DO (Subst. No. 1091)

  1. European characterization factors for human health damage of PM 10 and ozone in life cycle impact assessment

    NASA Astrophysics Data System (ADS)

    van Zelm, Rosalie; Huijbregts, Mark A. J.; den Hollander, Henri A.; van Jaarsveld, Hans A.; Sauter, Ferd J.; Struijs, Jaap; van Wijnen, Harm J.; van de Meent, Dik

    This paper presents characterization factors (CFs) for human health effects of fine particulate (PM 10) and ozone in Europe for the purpose of life cycle impact assessment. The CFs express the change in disability adjusted life years (DALYs) of European inhabitants due to a change in emissions of PM 10, ammonia (NH 3), nitrogen oxides (NO x), sulfur dioxide (SO 2), and non-methane volatile organic compounds (NMVOCs). The CF consists of an intake factor, an effect factor, and a damage factor. The intake factor was modeled as the change in population exposure to primary and secondary aerosols, and ozone due to a change in emission of a substance. This was done with the models EUTREND (aerosols) and LOTOS-EUROS (ozone). A combined human effect and damage factor, represented by the change in DALY due to a change in population intake was derived from epidemiological-based relative risks of short-term mortality, long-term mortality, and morbidity. Primary PM 10 causes 260 DALYs per kton emission, while secondary aerosol formation results in CFs between 51 and 83 DALYs per kton of precursor emitted. Applying CFs for high and low stack sources separately for PM 10 and SO 2 life cycle emissions can lead to a better estimation of human health damage due to these pollutants. CF related to ozone formation emissions appear to be much lower (0.04 DALY per kton, calculated based on maximum daily 8-h average ozone concentration) compared to the CF for primary and secondary PM 10. When calculating CF based on 24-h average ozone concentration, NMVOC causes 0.04 DALYs per kton, while the CF for NO x causing ozone formation is negative due to reactivity of ozone with NO in areas with high NO x levels (-0.12 DALYs per kton). Total European emissions of the five priority air pollutants in year 2000 are attributed to 4.2 million DALYs for the European population, which corresponds on average to 0.25 DALYs per person over a lifetime (80 years).

  2. Estimation of ozone with total ozone portable spectroradiometer instruments. II. Practical operation and comparisons

    NASA Astrophysics Data System (ADS)

    Labow, Gordon J.; Flynn, Lawrence E.; Rawlins, Michael A.; Beach, Robert A.; Simmons, C. A.; Schubert, C. M.

    1996-10-01

    We used a microcomputer-controlled total ozone portable spectroradiometer instrument 21 (MTOPS21) to measure solar radiation at 298, 304 and 310 nm in Greenbelt, Md., during 1995. One day s ozone measurements from a Brewer instrument (B105) were used to calibrate the 304- and 310-nm channel ratios to a theoretical model. Total ozone estimates were then determined for the entire MTOPS21 data set. Differences between individual B105 and MTOPS21 ozone estimates show a 1 drop as solar zenith angles increase and depend on atmospheric attenuation and SO 2 variation at the 2 level. Daily average values agree well ( 0.5 average offset, 2 standard deviation).

  3. Anthropogenic emissions in Nigeria and implications for atmospheric ozone pollution: A view from space

    NASA Astrophysics Data System (ADS)

    Marais, E. A.; Jacob, D. J.; Wecht, K.; Lerot, C.; Zhang, L.; Yu, K.; Kurosu, T. P.; Chance, K.; Sauvage, B.

    2014-12-01

    Nigeria has a high population density and large fossil fuel resources but very poorly managed energy infrastructure. Satellite observations of formaldehyde (HCHO) and glyoxal (CHOCHO) reveal very large sources of anthropogenic nonmethane volatile organic compounds (NMVOCs) from the Lagos megacity and oil/gas operations in the Niger Delta. This is supported by aircraft observations over Lagos and satellite observations of methane in the Niger Delta. Satellite observations of carbon monoxide (CO) and nitrogen dioxide (NO2) show large seasonal emissions from open fires in December-February (DJF). Ventilation of central Nigeria is severely restricted at that time of year, leading to very poor ozone air quality as observed from aircraft (MOZAIC) and satellite (TES). Simulations with the GEOS-Chem chemical transport model (CTM) suggest that maximum daily 8-h average (MDA8) ozone exceeds 70 ppbv over the region on a seasonal mean basis, with significant contributions from both open fires (15-20 ppbv) and fuel/industrial emissions (7-9 ppbv). The already severe ozone pollution in Nigeria could worsen in the future as a result of demographic and economic growth, although this would be offset by a decrease in open fires.

  4. Ozone pollution regimes modeled for a summer season in California’s San Joaquin Valley: A cluster analysis

    NASA Astrophysics Data System (ADS)

    Jin, Ling; Harley, Robert A.; Brown, Nancy J.

    2011-09-01

    This study demonstrates an application of cluster analysis to model simulation data for California's San Joaquin Valley (SJV) for the purpose of identifying meteorologically representative pollution regimes. Principal component analysis is employed to facilitate exploring and visualizing temporal variations in highly resolved gridded model data. Six regimes are clustered according to the spatial distribution of SJV 8 h ozone maxima. Meteorological effects (temperature and winds) are shown to explain the observed ozone spatial distributions in the SJV, and their relationship to those in upwind San Francisco Bay Area air basin (SFB) under certain prevailing wind flow patterns. In general, average ozone levels in the SJV increase with temperature, while their spatial distributions depend on flow regimes, especially the strength of sea breezes and upslope flows. More ventilated flow regimes, associated with stronger sea breeze and upslope flows, cause eastward transport of pollutants, increasing ozone in the southeastern SJV and decreasing it in the northwest SJV. The opposite occurs during the most stagnant conditions associated with the weakest sea breeze and upslope flows. The two most prominent relationships between the SFB and SJV were found to be associated with the most ventilated and the most stagnant conditions, respectively, indicating a strong inter-basin transport (or the lack thereof) event. Spatial representativeness of existing measurement sites and the confounding influences of emission changes on clustering results are also investigated. Existing measurement sites are able to capture ozone spatial patterns in the SFB and Sacramento Valley (SV), whereas those along the western side of the SJV are under-represented. Differences in day-of-week emissions produce minor effects on spatial ozone distributions and the clusters are largely stable under these changes.

  5. The 1977 surface ozone study of eastern Virginia

    NASA Technical Reports Server (NTRS)

    Williams, M. E.; Parsons, C. L.

    1978-01-01

    Data were collected by primarily twelve ground stations positioned throughout the eastern shore - tidewater area of Virginia and North Carolina. From an analysis of the ozone and wind data, certain trends were found such as the existence of a bias in ozone concentrations between stations and a linear correlation between average ozone concentration and latitude. In addition, higher ozone levels were found with surface winds from certain preferred directions at the various sites. The results, however, do not substantiate ozone or ozone precursor transport.

  6. Observations of the Antarctic Ozone Hole from 2003 to 2014

    NASA Astrophysics Data System (ADS)

    Braathen, Geir O.

    2015-04-01

    The Global Atmosphere Watch of WMO includes several stations in Antarctica that keep a close eye on the ozone layer during the ozone hole season. Observations made during the ozone holes from 2003 to 2014 will be compared to each other and interpreted in light of the meteorological conditions. Satellite observations will be used to get a more general picture of the size and depth of the ozone hole and will also be used to calculate various metrics for ozone hole severity. In 2003, 2005 and 2006, the ozone hole was relatively large with more ozone loss than normal. This is in particular the case for 2006, which by most ozone hole metrics was the most severe ozone hole on record. On the other hand, the ozone holes of 2004, 2007, 2010 and 2012 were less severe than normal, and only the very special ozone hole of 2002 had less ozone depletion when one regards the ozone holes of the last decade. The ozone hole of 2011 suffered more ozone depletion than in 2010, but it was quite average in comparison to other years of the last decade. The situation was similar in 2013 and 2014. The interannual variability will be discussed with the help of meteorological data, such as temperature conditions, possibility for polar stratospheric clouds, vortex shape and vortex longevity.

  7. Quantitative characterization of the Antarctic ozone hole

    NASA Technical Reports Server (NTRS)

    Ito, T.; Sakoda, Y.; Matsubara, K.; Takao, T.; Akagi, K.; Watanabe, Y.; Shibata, S.; Naganuma, H.

    1994-01-01

    The long-term evolution of the Antarctic ozone hole is studied based on the TOMS data and the JMA data-set of stratospheric temperature in relation with the possible role of polar stratospheric clouds (PSC's). The effective mass of depleted ozone in the ozone hole at its annual mature stage reached a historical maximum of 55 Mt in 1991, 4.3 times larger than in 1981. The ozone depletion rate during 30 days before the mature ozone hole does not show any appreciable long-term trend but the interannual fluctuations do, ranging from 0.169 to 0.689 Mt/day with the average of 0.419 Mt/day for the period of 1979 - 1991. The depleted ozone mass has the highest correlation with the region below 195 K on the 30 mb surface in June, whereas the ozone depletion rate correlates most strongly with that in August. The present result strongly suggests that the long-term evolution of the mature ozone hole is caused both by the interannual change of the latitudinal coverage of the early PSC's, which may control the latitude and date of initiation of ozone decrease, and by that of the spatial coverage of the mature PSC's which may control the ozone depletion rate in the Antarctic spring.

  8. TROP OZONE

    EPA Science Inventory

    Activity Area (F01) The NRMRL tropospheric ozone research program is both coordinated with the research efforts of others and planned to achieve the most important unmet research needs that draw upon its unique expertise. For example, NRMRL emissions research in this area is co...

  9. Association of short-term exposure to ground-level ozone and respiratory outpatient clinic visits in a rural location – Sublette County, Wyoming, 2008–2011

    SciTech Connect

    Pride, Kerry R.; Peel, Jennifer L.; Robinson, Byron F.; Busacker, Ashley; Grandpre, Joseph; Bisgard, Kristine M.; Yip, Fuyuen Y.; Murphy, Tracy D.

    2015-02-15

    Objective: Short-term exposure to ground-level ozone has been linked to adverse respiratory and other health effects; previous studies typically have focused on summer ground-level ozone in urban areas. During 2008–2011, Sublette County, Wyoming (population: ~10,000 persons), experienced periods of elevated ground-level ozone concentrations during the winter. This study sought to evaluate the association of daily ground-level ozone concentrations and health clinic visits for respiratory disease in this rural county. Methods: Clinic visits for respiratory disease were ascertained from electronic billing records of the two clinics in Sublette County for January 1, 2008–December 31, 2011. A time-stratified case-crossover design, adjusted for temperature and humidity, was used to investigate associations between ground-level ozone concentrations measured at one station and clinic visits for a respiratory health concern by using an unconstrained distributed lag of 0–3 days and single-day lags of 0 day, 1 day, 2 days, and 3 days. Results: The data set included 12,742 case-days and 43,285 selected control-days. The mean ground-level ozone observed was 47±8 ppb. The unconstrained distributed lag of 0–3 days was consistent with a null association (adjusted odds ratio [aOR]: 1.001; 95% confidence interval [CI]: 0.990–1.012); results for lags 0, 2, and 3 days were consistent with the null. However, the results for lag 1 were indicative of a positive association; for every 10-ppb increase in the 8-h maximum average ground-level ozone, a 3.0% increase in respiratory clinic visits the following day was observed (aOR: 1.031; 95% CI: 0.994–1.069). Season modified the adverse respiratory effects: ground-level ozone was significantly associated with respiratory clinic visits during the winter months. The patterns of results from all sensitivity analyzes were consistent with the a priori model. Conclusions: The results demonstrate an association of increasing ground

  10. Effects of stratospheric ozone recovery on tropospheric chemistry and air quality

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Wu, S.; Wang, Y.

    2013-08-01

    The stratospheric ozone has decreased greatly since 1980 due to ozone depleting substances (ODSs). As a result of the implementation of the Montreal Protocol and its amendments and adjustments, stratospheric ozone is expected to recover towards its pre-1980 level in the coming decades. We examine the implications of stratospheric ozone recovery for the tropospheric chemistry and ozone air quality with a global chemical transport model (GEOS-Chem). Significant decreases in surface ozone photolysis rates due to stratospheric ozone recovery are simulated. Increases in ozone lifetime by up to 7% are calculated in the troposphere. The global average OH decreases by 1.74% and the global burden of tropospheric ozone increases by 0.78%. The perturbations to tropospheirc ozone and surface ozone show large seasonal and spatial variations. General increases in surface ozone are calculated for each season, with increases by up to 5% for some regions.

  11. Impacts of Stratospheric Ozone Change on Tropospheric Chemistry and Air Quality

    NASA Astrophysics Data System (ADS)

    Wu, S.; Zhang, H.

    2013-05-01

    The stratospheric ozone has decreased greatly since 1980 due to ozone depleting substances (ODSs). As a result of the implementation of the Montreal Protocol and its Amendments and Adjustments, stratospheric ozone is expected to recover towards its pre-1980 level in the coming decades. We examine the implications of stratospheric ozone recovery for the tropospheric chemistry and ozone air quality with a global chemical transport model (GEOS-Chem). Significant decreases in surface ozone photolysis rates due to stratospheric ozone recovery are simulated. Increases in ozone lifetime by up to 7% are calculated in the troposphere. The global average OH decreases by 1.74% and the global burden of tropospheric ozone increased by 0.78%. The perturbations to tropospheirc ozone and surface ozone show large seasonal and spatial variations. General increases in surface ozone are calculated for each season, with increases by up to 5% for some regions.

  12. Nanoscale assemblies of gigantic molecular {Mo154}-rings: (dimethyldioctadecylammonium)20[Mo154O462H8(H2O)70].

    PubMed

    Akutagawa, Tomoyuki; Jin, Reina; Tunashima, Ryo; Noro, Shin-Ichiro; Cronin, Leroy; Nakamura, Takayoshi

    2008-01-01

    Clusters based on the mixed-valence gigantic inorganic ring [Mo154O462H14(H2O)70]14- ({Mo154}-ring) and dimethyldioctadecylammonium (DODA) were combined to form novel molecular assemblies of an inorganic-organic hybrid molecular system as Langmuir-Blodgett (LB) and cast films. (DODA)20[Mo154O462H8(H2O)70] (2) was prepared by cation exchange and was characterized by a combination of thermogravimetry, IR, UV-vis-NIR, 1H NMR, and XRD measurements. The salt 2 was soluble in common organic solvents, and the chemical stability of {Mo154}-ring encapsulated by DODA cationic surfactants in CHCl3 was found to be higher than that of the "native" sodium salt of the {Mo154}-ring in H2O. Uniform spherical vesicle-like molecular assemblies of (DODA)20[Mo154O462H8(H2O)70] were observed in dilute THF, whose average diameter of 95 nm and a normalized variance of 5.7% were confirmed by a X-ray small-angle scattering. Deposition of 2 as a cast film showed circular domains with a typical diameter of approximately 100 nm, indicating possible similarities between solution and surface-deposited structures. The resulting LB films of salt 2 were transferred from an acidic buffer subphase with pH = 1.5 onto mica, giving a two-dimensional film surface with a unity transfer ratio. Further, the electronic absorption spectra of the LB multilayer were consistent with the classic type II mixed-valence MoV/MoVI electronic state well know for molybdenum blue {Mo154}-ring systems, and it appears that on the surface the plane of the {Mo154}-ring is approximately parallel to the substrate surface, as indicated by polarized electronic spectra, while the alkyl chains of DODA were relatively normal to the substrate surface. Therefore, the layer between the {Mo154}-rings and DODA cations was alternately stacked along the direction of film propagation. Finally, it was found that the surface morphology of the cast and LB films was determined by the molecular assembly of (DODA)20[Mo154O462H8(H2O)70] in

  13. Nqrs Data for C8H7ClN2O3 (Subst. No. 1078)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H7ClN2O3 (Subst. No. 1078)

  14. Nqrs Data for C8H6O4 (Subst. No. 1074)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H6O4 (Subst. No. 1074)

  15. NQRS Data for C8H7Cl5NSb (Subst. No. 1082)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H7Cl5NSb (Subst. No. 1082)

  16. NQRS Data for C8H7BrO (Subst. No. 1076)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H7BrO (Subst. No. 1076)

  17. NQRS Data for C8H20Br3GeN (Subst. No. 1129)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H20Br3GeN (Subst. No. 1129)

  18. NQRS Data for C8H10BrN (Subst. No. 1096)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H10BrN (Subst. No. 1096)

  19. Nqrs Data for C8H7ClN2O3 (Subst. No. 1079)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H7ClN2O3 (Subst. No. 1079)

  20. Recent Stratospheric Ozone Measurements over Ankara-Turkey and Evaluation of Ozone Profiles

    NASA Astrophysics Data System (ADS)

    Ozkizilkaya, O.; Incecik, S.; Kahya, C.

    2009-04-01

    Satellite, spectrophotometer and ozonesonde measurement systems are widely used to determine total column of ozone and its properties in troposphere and stratosphere. The differences between these measurement systems are the main research areas in terms of their techniques and results. The present study deals with to compare of satellite total ozone measurements from OMI and SEVIRI instruments, Brewer MKIII spectrophotometer and ECC ozonesonde total ozone measurements and to make an assessment of the ozone in troposphere and stratosphere using ECC and Brewer ozone profiles over Ankara (39o55´N; 32o55´E) located at the centre of Anatolia. In this study, Brewer MKIII, OMI and SEVIRI total ozone data of Ankara for the period January -December 2007 were used to make an intercomparison of monthly average total ozone measurements. The percentage differences between the data sets were calculated. It is aimed to define which remote sensing measurement techniques give the most accurate and reliable results. In order to verify the data obtained by remote sensing methods, 21 daily ECC total ozone measurements for the same period were used. Brewer, OMI and SEVIRI measurements available for the corresponding days were taken into account. Furthermore, in order to understand atmospheric ozone content, a total ozone retrieval algorithm from ECC sounding was applied to both troposphere and stratosphere to determine the ozone contents. According to the comparisons, it was found that Brewer and OMI monthly average total ozone measurements show good agreement but SEVIRI overestimates; maximum differences between the measurements occur mostly between July and October. Maximum percentage differences between Brewer and OMI, SEVIRI and Brewer, SEVIRI and OMI were found -7.3%, 17% and 17% respectively. The mean absolute differences between Brewer and OMI were calculated as 2.4%; on the other hand SEVIRI has 10.4% mean absolute difference from Brewer and OMI. The results of the comparison

  1. Ozone uptake by citrus trees exposed to a range of ozone concentrations

    NASA Astrophysics Data System (ADS)

    Fares, Silvano; Park, Jeong-Hoo; Ormeno, Elena; Gentner, Drew R.; McKay, Megan; Loreto, Francesco; Karlik, John; Goldstein, Allen H.

    2010-09-01

    The Citrus genus includes a large number of species and varieties widely cultivated in the Central Valley of California and in many other countries having similar Mediterranean climates. In the summer, orchards in California experience high levels of tropospheric ozone, formed by reactions of volatile organic compounds (VOC) with oxides of nitrogen (NO x). Citrus trees may improve air quality in the orchard environment by taking up ozone through stomatal and non-stomatal mechanisms, but they may ultimately be detrimental to regional air quality by emitting biogenic VOC (BVOC) that oxidize to form ozone and secondary organic aerosol downwind of the site of emission. BVOC also play a key role in removing ozone through gas-phase chemical reactions in the intercellular spaces of the leaves and in ambient air outside the plants. Ozone is known to oxidize leaf tissues after entering stomata, resulting in decreased carbon assimilation and crop yield. To characterize ozone deposition and BVOC emissions for lemon ( Citrus limon), mandarin ( Citrus reticulata), and orange ( Citrus sinensis), we designed branch enclosures that allowed direct measurement of fluxes under different physiological conditions in a controlled greenhouse environment. Average ozone uptake was up to 11 nmol s -1 m -2 of leaf. At low concentrations of ozone (40 ppb), measured ozone deposition was higher than expected ozone deposition modeled on the basis of stomatal aperture and ozone concentration. Our results were in better agreement with modeled values when we included non-stomatal ozone loss by reaction with gas-phase BVOC emitted from the citrus plants. At high ozone concentrations (160 ppb), the measured ozone deposition was lower than modeled, and we speculate that this indicates ozone accumulation in the leaf mesophyll.

  2. The Antarctic Ozone Hole

    ERIC Educational Resources Information Center

    Jones, Anna E.

    2008-01-01

    Since the mid 1970s, the ozone layer over Antarctica has experienced massive destruction during every spring. In this article, we will consider the atmosphere, and what ozone and the ozone layer actually are. We explore the chemistry responsible for the ozone destruction, and learn about why conditions favour ozone destruction over Antarctica. For…

  3. Ozone and aircraft operations

    NASA Technical Reports Server (NTRS)

    Perkins, P. J.

    1981-01-01

    The cabin ozone problem is discussed. Cabin ozone in terms of health effects, the characteristics of ozone encounters by aircraft, a brief history of studies to define the problem, corrective actions taken, and possible future courses of action are examined. It is suggested that such actions include avoiding high ozone concentrations by applying ozone forecasting in flight planning procedures.

  4. Diurnal variations of stratospheric ozone measured by ground-based microwave remote sensing at the Mauna Loa NDACC site: measurement validation and GEOSCCM model comparison

    NASA Astrophysics Data System (ADS)

    Parrish, A.; Boyd, I. S.; Nedoluha, G. E.; Bhartia, P. K.; Frith, S. M.; Kramarova, N. A.; Connor, B. J.; Bodeker, G. E.; Froidevaux, L.; Shiotani, M.; Sakazaki, T.

    2013-12-01

    There is presently renewed interest in diurnal variations of stratospheric and mesospheric ozone for the purpose of supporting homogenization of records of various ozone measurements that are limited by the technique employed to being made at certain times of day. We have made such measurements for 18 yr using a passive microwave remote sensing technique at the Mauna Loa Observatory in Hawaii, which is a primary station in the Network for Detection of Atmospheric Composition Change (NDACC). We have recently reprocessed these data with hourly time resolution to study diurnal variations. We inspected differences between pairs of the ozone spectra (e.g. day and night) from which the ozone profiles are derived to determine the extent to which they may be contaminated by diurnally varying systematic instrumental or measurement effects. These are small, and we have reduced them further by selecting data that meet certain criteria that we established. We have calculated differences between profiles measured at different times: morning-night, afternoon-night, and morning-afternoon and have intercompared these with like profiles derived from Aura-MLS, UARS-MLS, SMILES, and SBUV/2 measurements. Differences between averages of coincident profiles are typically <1.5% of typical nightime values over most of the covered altitude range with some exceptions. We calculated averages of ozone values for each hour from the Mauna Loa microwave data, and normalized these to the average for the first hour after midnight for comparison with corresponding values calculated with the Goddard Earth Observing System Chemistry Climate Model (GEOSCCM). We found that the measurements and model output mostly agree to better than 1.5% of the midnight value, with one noteworthy exception: the measured morning-night values are significantly (2-3%) higher than the modeled ones from 3.2 to 1.8 hPa (~39-43 km), and there is evidence that the measured values are increasing compared to the modeled values

  5. Earth's Endangered Ozone

    ERIC Educational Resources Information Center

    Panofsky, Hans A.

    1978-01-01

    Included are (1) a discussion of ozone chemistry; (2) the effects of nitrogen fertilizers, fluorocarbons, and high level aircraft on the ozone layer; and (3) the possible results of a decreasing ozone layer. (MR)

  6. A Procedure for Inter-Comparing the Skill of Regional-Scale Air Quality Model Simulations of Daily Maximum 8-Hour Ozone Concentrations

    EPA Science Inventory

    An operational model evaluation procedure is described to quantitatively assess the relative skill among several regionalscale air quality models simulating various percentiles of the cumulative frequency distribution of observed daily maximum 8-h ozone concentrations. Bootstrap ...

  7. Ozone crisis

    SciTech Connect

    Roan, S.

    1989-01-01

    The author presents an account of the depletion of the atmosphere's ozone layer since the discovery of the phenomenon 15 years ago. The book recounts the flight to ban chlorofluorocarbons (CFC's) and describes the science, the people, and the politics involved, up to the March 1988 international treaty restricting CFC production. It surveys the media's coverage, describes the struggle for remedies, and offers a prognosis for the future.

  8. Antarctic ozone loss in 1979-2010: first sign of ozone recovery

    NASA Astrophysics Data System (ADS)

    Kuttippurath, J.; Lefèvre, F.; Pommereau, J.-P.; Roscoe, H. K.; Goutail, F.; Pazmiño, A.; Shanklin, J. D.

    2013-02-01

    A long-term ozone loss time series is necessary to understand the evolution of ozone in Antarctica. Therefore, we construct the time series using ground-based, satellite and bias-corrected multi-sensor reanalysis (MSR) data sets for the period 1989-2010. The trends in ozone over 1979-2010 are also estimated to further elucidate its evolution in the wake of decreasing halogen levels in the stratosphere. Our analysis with ground-based observations shows that the average ozone loss in the Antarctic is about -33 to -50% (-90 to -155 DU (Dobson Unit)) in 1989-1992, and then stayed at around -48% (-160 DU). The ozone loss in the warmer winters (e.g. 2002 and 2004) is lower (-37 to -46%), and in the very cold winters (e.g. 2003 and 2006) it is higher (-52 to -55%). These loss estimates are in good agreement with those estimated from satellite observations, where the differences are less than ±3%. The ozone trends based on the equivalent effective Antarctic stratospheric chlorine (EEASC) and piecewise linear trend (PWLT) functions for the vortex averaged ground-based, Total Ozone Mapping Spectrometer/Ozone Monitoring Instrument (TOMS/OMI), and MSR data averaged over September-November exhibit about -4.6 DU yr-1 over 1979-1999, corroborating the role of halogens in the ozone decrease during the period. The ozone trends computed for the 2000-2010 period are about +1 DU yr-1 for EEASC and +2.6 DU yr-1 for the PWLT functions. The larger positive PWLT trends for the 2000-2010 period indicate the influence of dynamics and other basis functions on the increase of ozone. The trends in both periods are significant at 95% confidence intervals for all analyses. Therefore, our study suggests that Antarctic ozone shows a significant positive trend toward its recovery, and hence, leaves a clear signature of the successful implementation of the Montreal Protocol.

  9. Mesospheric ozone measurements by SAGE II

    NASA Astrophysics Data System (ADS)

    Chu, D. A.; Cunnold, D. M.

    1994-04-01

    SAGE II observations of ozone at sunrise and sunset (solar zenith angle = 90 deg) at approximately the same tropical latitude and on the same day exhibit larger concentrations at sunrise than at sunset between 55 and 65 km. Because of the rapid conversion between atomic oxygen and ozone, the onion-peeling scheme used in SAGE II retrievals, which is based on an assumption of constant ozone, is invalid. A one-dimensional photochemical model is used to simulate the diurnal variation of ozone particularly within the solar zenith angle of 80 deg - 100 deg. This model indicates that the retrieved SAGE II sunrise and sunset ozone values are both overestimated. The Chapman reactions produce an adequate simulation of the ozone sunrise/sunset ratio only below 60 km, while above 60 km this ratio is highly affected by the odd oxygen loss due to odd hydrogen reactions, particularly OH. The SAGE II ozone measurements are in excellent agreement with model results to which an onion peeling procedure is applied. The SAGE II ozone observations provide information on the mesospheric chemistry not only through the ozone profile averages but also from the sunrise/sunset ratio.

  10. Mesospheric ozone measurements by SAGE II

    NASA Technical Reports Server (NTRS)

    Chu, D. A.; Cunnold, D. M.

    1994-01-01

    SAGE II observations of ozone at sunrise and sunset (solar zenith angle = 90 deg) at approximately the same tropical latitude and on the same day exhibit larger concentrations at sunrise than at sunset between 55 and 65 km. Because of the rapid conversion between atomic oxygen and ozone, the onion-peeling scheme used in SAGE II retrievals, which is based on an assumption of constant ozone, is invalid. A one-dimensional photochemical model is used to simulate the diurnal variation of ozone particularly within the solar zenith angle of 80 deg - 100 deg. This model indicates that the retrieved SAGE II sunrise and sunset ozone values are both overestimated. The Chapman reactions produce an adequate simulation of the ozone sunrise/sunset ratio only below 60 km, while above 60 km this ratio is highly affected by the odd oxygen loss due to odd hydrogen reactions, particularly OH. The SAGE II ozone measurements are in excellent agreement with model results to which an onion peeling procedure is applied. The SAGE II ozone observations provide information on the mesospheric chemistry not only through the ozone profile averages but also from the sunrise/sunset ratio.

  11. Trends in Dobson total ozone - An update through 1983

    NASA Astrophysics Data System (ADS)

    Oehlert, G. W.

    1986-02-01

    Trends in Dobson total ozone values from 1970-1983 are analyzed using ozone data collected from 36 Dobson stations between January 1964-December 1983. The trend methodology employed in this study is described; a hockey stick series and a monthly average observed 10.7-cm solar flux series are the predictors for the two sets of total ozone data. The frequency domain trend estimations for the ozone data published by the World Ozone Data Center and for the intervention adjusted set are examined. It is observed that the total ozone trend from 1970-1983 is negative and ranges from -0.31 percent/decade + or - 0.49 percent/decade for unadjusted data to -1.10 percent/decade + or - 0.47 percent/decade for data adjusted for solar cycle changes and instrument interventions. The effect of abnormally low total ozone values in the northern hemisphere during 1983 on the ozone trends is discussed.

  12. Photochemical model evaluation of the ground-level ozone impacts on ambient air quality and vegetation health in the Alberta oil sands region: Using present and future emission scenarios

    NASA Astrophysics Data System (ADS)

    Vijayaraghavan, Krish; Cho, Sunny; Morris, Ralph; Spink, David; Jung, Jaegun; Pauls, Ron; Duffett, Katherine

    2016-09-01

    One of the potential environmental issues associated with oil sands development is increased ozone formation resulting from NOX and volatile organic compound emissions from bitumen extraction, processing and upgrading. To manage this issue in the Athabasca Oil Sands Region (AOSR) in northeast Alberta, a regional multi-stakeholder group, the Cumulative Environmental Management Association (CEMA), developed an Ozone Management Framework that includes a modelling based assessment component. In this paper, we describe how the Community Multi-scale Air Quality (CMAQ) model was applied to assess potential ground-level ozone formation and impacts on ambient air quality and vegetation health for three different ozone precursor cases in the AOSR. Statistical analysis methods were applied, and the CMAQ performance results met the U.S. EPA model performance goal at all sites. The modelled 4th highest daily maximum 8-h average ozone concentrations in the base and two future year scenarios did not exceed the Canada-wide standard of 65 ppb or the newer Canadian Ambient Air Quality Standards of 63 ppb in 2015 and 62 ppb in 2020. Modelled maximum 1-h ozone concentrations in the study were well below the Alberta Ambient Air Quality Objective of 82 ppb in all three cases. Several ozone vegetation exposure metrics were also evaluated to investigate the potential impact of ground-level ozone on vegetation. The chronic 3-months SUM60 exposure metric is within the CEMA baseline range (0-2000 ppb-hr) everywhere in the AOSR. The AOT40 ozone exposure metric predicted by CMAQ did not exceed the United Nations Economic Commission for Europe (UN/ECE) threshold of concern of 3000 ppb-hr in any of the cases but is just below the threshold in high-end future emissions scenario. In all three emission scenarios, the CMAQ predicted W126 ozone exposure metric is within the CEMA baseline threshold of 4000 ppb-hr. This study outlines the use of photochemical modelling of the impact of an industry (oil

  13. Candidate Resonant Tetraneutron State Populated by the 4He (8H3, 8Be) ) Reaction

    NASA Astrophysics Data System (ADS)

    Kisamori, K.; Shimoura, S.; Miya, H.; Michimasa, S.; Ota, S.; Assie, M.; Baba, H.; Baba, T.; Beaumel, D.; Dozono, M.; Fujii, T.; Fukuda, N.; Go, S.; Hammache, F.; Ideguchi, E.; Inabe, N.; Itoh, M.; Kameda, D.; Kawase, S.; Kawabata, T.; Kobayashi, M.; Kondo, Y.; Kubo, T.; Kubota, Y.; Kurata-Nishimura, M.; Lee, C. S.; Maeda, Y.; Matsubara, H.; Miki, K.; Nishi, T.; Noji, S.; Sakaguchi, S.; Sakai, H.; Sasamoto, Y.; Sasano, M.; Sato, H.; Shimizu, Y.; Stolz, A.; Suzuki, H.; Takaki, M.; Takeda, H.; Takeuchi, S.; Tamii, A.; Tang, L.; Tokieda, H.; Tsumura, M.; Uesaka, T.; Yako, K.; Yanagisawa, Y.; Yokoyama, R.; Yoshida, K.

    2016-02-01

    A candidate resonant tetraneutron state is found in the missing-mass spectrum obtained in the double-charge-exchange reaction 4He (8H3, 8Be) at 186 MeV /u . The energy of the state is 0.83 ±0.65 (stat ) ±1.25 (syst ) MeV above the threshold of four-neutron decay with a significance level of 4.9 σ . Utilizing the large positive Q value of the (8He, 8Be) reaction, an almost recoilless condition of the four-neutron system was achieved so as to obtain a weakly interacting four-neutron system efficiently.

  14. Thermolysis of ZroC1/sub 2/. 8H/sub 2/O

    SciTech Connect

    Nirsha, B.M.; Malinovskii, V.N.; Mtskhvetaridze, N.E.; Olikova, V.A.; Tyotyoeva, N.N.; Zhadanov, B.V.

    1986-07-01

    The authors study the thermolysis of ZrOC1/sub 2/ . 8H/sub 2/O by the methods of thermogravimetry, x-ray phase analysis, and IR spectroscopy. It is shown that the dehydration process terminates with the formation of x-ray amorphous products, apparently containing a mixture of hydroxo- and water-free zirconium oxochloride. The thermolysis of the latter proceeds according to different schemes, but leads to the formation of amorphous zirconium dioxide. The dioxide crystallizes at 690 K in a tetragonal form, which transforms into the monoclinic form when heated up to 1270 K.

  15. User's guide for SBUV/TOMS ozone derivative products

    NASA Technical Reports Server (NTRS)

    Fleig, A. J.; Wellemeyer, C.; Oslik, N.; Lee, D.; Miller, J.; Magatani, R.

    1984-01-01

    A series of products are available derived from the total-ozone and ozone vertical profile results for the Solar Backscattered Ultraviolet/Total-Ozone Mapping Spectrometer (SBUV/TOMS) Nimbus-7 operation. Products available are (1) orbital height-latitude cross sections of the SBUV profile data, (2) daily global total ozone contours in polar coordinates, (3) daily averages of total ozone in global 5x5 degree latitude-longitude grid, (4) daily, monthly and quarterly averages of total ozone and profile data in 10 degree latitude zones, (5) tabular presentation of zonal means, (6) daily global total ozone and profile contours in polar coordinates. The ""Derivative Products User's Guide'' describes each of these products in detail, including their derivation and presentation format. Information is provided on how to order the tapes and microfilm from the National Space Science Data Center.

  16. TOTAL Column Ozone from OMI - Continuuing the LONG TERM DATA Record

    NASA Astrophysics Data System (ADS)

    McPeters, R. D.; Frith, S. M.; Labow, G. J.; Seftor, C. J.

    2014-12-01

    We now have a ten year record of total column ozone from Aura OMI that continues the long term record tracking the change in global ozone. OMI has proven to be one of the most stable ozone monitoring instruments ever flown. OMI ozone agrees well with that from the Merged Ozone Dataset (MOD) created by combining data from a series of SBUV/2 instruments. OMI ozone is 1.5% lower than that from MOD, but this is explained almost entirely by the use of the older Bass and Paur ozone cross sections. Similarly, OMI ozone agrees well with ozone from an average of 73 northern hemisphere Dobson and Brewer stations, and OMI ozone also agrees well with data from the recently launched OMPS ozone nadir mapper on NPP for the two year period of overlap.

  17. [Temporal and spatial distribution characteristics of ozone in Beijing].

    PubMed

    Wang, Zhan-shan; Li, Yun-ting; Chen, Tian; Zhang, Da-wei; Sun, Feng; Sun, Rui-wen; Dong, Xin; Sun, Nai-di; Pan, Li-bo

    2014-12-01

    Ozone concentrations obtained from 35 automatic air monitoring stations in Beijing were analyzed to investigate their temporal and spatial distribution characteristics. A process with high ozone concentration in summer was analyzed. The results showed that ozone maintained relatively high concentration from May to August while in other months, the ozone concentration was at a low level. Overall, the average concentrations of ozone in different stations in a descending order were comparison and regional station, suburban environment evaluation station, urban environmental assessment station and traffic pollution monitoring station. Ozone diurnal variation showed a single peak distribution, the peak of which appeared at 15:00 or 16:00. Ozone concentration showed obvious weekend effect, which meant ozone concentration in daytime of weekend was higher than that in weekday. Ozone concentration was lower in urban Beijing, higher in surrounding counties and the highest in northeast area with more vegetation. A high ozone concentration process occurred in Beijing on June 3, 2013. Under the effect of southwest wind in the afternoon, the concentration peaks of ozone in Yufa, Fengtaihuayuan, Olympic center and Huairou station occurred in order from south to north. Concentration peak of ozone in Huairou station occurred at 20:00 in the night. It could be concluded that significant ozone transmission characteristic was reflected in this process. PMID:25826912

  18. Initial field evaluation of the Harvard active ozone sampler for personal ozone monitoring.

    PubMed

    Geyh, A S; Roberts, P T; Lurmann, F W; Schoell, B M; Avol, E L

    1999-01-01

    Assessing personal exposure to ozone has only been feasible recently with the introduction of passive ozone samplers. These devices are easy to use, but changes in air velocity across their collection surfaces can affect performance. The Harvard active ozone sampler (AS) was developed in response to problems with the passive methods. This active sampler has been tested extensively as a microenvironmental sampler. To test for personal sampling, 40 children attending summer day-camp in Riverside, California wore the active ozone sampler for approximately 2.6 h on July 19 and 21, 1994, when ozone concentrations were about 100 ppb and 140 ppb, respectively. The children spent 94-100% of the sampling period outside, staying within a well-defined area while participating in normal camp activities. Ambient ozone concentrations across this area were monitored by two UV photometric ozone monitors. The active sampler was worn in a small backpack that was also equipped with a passive ozone sampler. Device precision, reported as the percent difference between duplicate pairs of samplers, was +/- 3.7% and +/- 4.2% for the active and passive samplers, respectively. The active sampler measured, on average, 94.5 +/- 8.2% of the ambient ozone while the passive samplers measured, on average, 124.5 +/- 18.8%. The samplers were worn successfully for the entire sampling period by all participating children. PMID:10321353

  19. Lanthanite-(Nd), Nd2(CO3)3·8H2O

    PubMed Central

    Morrison, Shaunna M.; Andrade, Marcelo B.; Wenz, Michelle D.; Domanik, Kenneth J.; Downs, Robert T.

    2013-01-01

    Lanthanite-(Nd), ideally Nd2(CO3)3·8H2O [dineodymium(III) tricarbonate octa­hydrate], is a member of the lanthanite mineral group characterized by the general formula REE 2(CO3)3·8H2O, where REE is a 10-coordinated rare earth element. Based on single-crystal X-ray diffraction of a natural sample from Mitsukoshi, Hizen-cho, Karatsu City, Saga Prefecture, Japan, this study presents the first structure determination of lanthanite-(Nd). Its structure is very similar to that of other members of the lanthanite group. It is composed of infinite sheets made up of corner- and edge-sharing of two NdO10-polyhedra (both with site symmetry ..2) and two carbonate triangles (site symmetries ..2 and 1) parallel to the ab plane, and stacked perpendicular to c. These layers are linked to one another only through hydrogen bonding involving the water mol­ecules. PMID:23476479

  20. Decadal evolution of the Antarctic ozone hole.

    PubMed

    Jiang, Y; Yung, Y L; Zurek, R W

    1996-04-20

    Ozone column amounts obtained by the total ozone mapping spectrometer (TOMS) in the southern polar region are analyzed during late austral winter and spring (days 240-300) for 1980-1991 using area-mapping techniques and area-weighted vortex averages. The vortex here is defined using the -50 PVU (1 PVU = 1.0 x 10(-6) K kg-1 m2 s-1) contour on the 500 K isentropic surface. The principal results are: (1) there is a distinct change after 1985 in the vortex-averaged column ozone depletion rate during September and October, the period of maximum ozone loss, and (2) the vortex-averaged column ozone in late August (day 240) has dropped by 70 Dobson units (DU) in a decade due to the loss in the dark and the dilution effect. The mean ozone depletion rate in the vortex between day 240 and the day of minimum vortex-averaged ozone is about 1 DU d-1 at the beginning of the decade, increasing to about 1.8 DU d-1 by 1985, and then apparently saturating thereafter. The vortex-average column ozone during September and October has declined at the rate of 11.3 DU yr-1 (3.8%) from 1980 to 1987 (90 DU over 8 years) and at a smaller rate of 2 DU yr-1 (0.9%) from 1987 to 1991 (10 DU over 5 years, excluding the anomalous year 1988). We interpret the year-to-year trend in the ozone depletion rate during the earlier part of the decade as due to the rise of anthropogenic chlorine in the atmosphere. The slower trend at the end of the decade indicates saturation of ozone depletion in the vortex interior, in that chlorine amounts in the mid-1980s were already sufficiently high to deplete most of the ozone in air within the isolated regions of the lower-stratospheric polar vortex. In subsequent years, increases in stratospheric chlorine may have enhanced wintertime chemical loss of ozone in the south polar vortex even before major losses during the Antarctic spring. PMID:11539364

  1. Influence of the ozone profile above Madrid (Spain) on Brewer estimation of ozone air mass factor

    NASA Astrophysics Data System (ADS)

    Antón, M.; López, M.; Costa, M. J.; Serrano, A.; Bortoli, D.; Bañón, M.; Vilaplana, J. M.; Silva, A. M.

    2009-08-01

    The methodology used by Brewer spectroradiometers to estimate the ozone column is based on differential absorption spectroscopy. This methodology employs the ozone air mass factor (AMF) to derive the total ozone column from the slant path ozone amount. For the calculating the ozone AMF, the Brewer algorithm assumes that the ozone layer is located at a fixed height of 22 km. However, for a real specific site the ozone presents a certain profile, which varies spatially and temporally depending on the latitude, altitude and dynamical conditions of the atmosphere above the site of measurements. In this sense, this work address the reliability of the mentioned assumption and analyses the influence of the ozone profiles measured above Madrid (Spain) in the ozone AMF calculations. The approximated ozone AMF used by the Brewer algorithm is compared with simulations obtained using the libRadtran radiative transfer model code. The results show an excellent agreement between the simulated and the approximated AMF values for solar zenith angle lower than 75°. In addition, the relative differences remain lower than 2% at 85°. These good results are mainly due to the fact that the altitude of the ozone layer assumed constant by the Brewer algorithm for all latitudes notably can be considered representative of the real profile of ozone above Madrid (average value of 21.7±1.8 km). The operational ozone AMF calculations for Brewer instruments are limited, in general, to SZA below 80°. Extending the usable SZA range is especially relevant for Brewer instruments located at high mid-latitudes.

  2. An improved measure of ozone depletion in the Antarctic stratosphere

    NASA Astrophysics Data System (ADS)

    Huck, P. E.; Tilmes, S.; Bodeker, G. E.; Randel, W. J.; McDonald, A. J.; Nakajima, H.

    2007-06-01

    Ozone mass deficit is a commonly used index to quantify Antarctic ozone depletion. However, as currently defined, this measure is not robust with respect to reflecting chemical ozone loss within the Antarctic vortex. Therefore, in this study, a new definition of ozone mass deficit (OMD) is developed. The 220 Dobson Unit based value currently used as the threshold for ozone depletion has been replaced with a new ozone background representative of pre-ozone-hole conditions. Second, the new OMD measure is based on ozone measurements within the dynamical vortex. A simpler method is also proposed whereby calculation of the vortex edge is avoided by using the average latitude of the vortex edge (62°S) as the spatial limiting contour. An indication of the errors in OMD introduced when using this simpler approach is provided. By comparing vortex average total ozone loss (defined using the new background and limiting contour) with partial column accumulated chemical ozone loss calculated with the tracer-tracer correlation method for 1992-2004 and in more detail for 1996 and 2003, it is shown that the new OMD measure is representative of chemical ozone loss within the vortex. In addition the new criteria have been applied to the calculation of ozone hole area. The sensitivity of the new measures to uncertainties in the background have been quantified. The new ozone loss measures underestimate chemical ozone loss in highly dynamically disturbed years (2002 and 2004), and criteria for identifying these years are presented. The new measures should aid chemistry-climate model intercomparisons since ozone biases in the models are avoided.

  3. The 14.8-h orbital period of GX339-4

    NASA Technical Reports Server (NTRS)

    Callanan, P. J.; Charles, P. A.; Honey, W. B.; Thorstensen, J. R.

    1992-01-01

    We present the results of photometric observations of the black hole candidate GX339-4, obtained while the system was in an 'off' state. We show that a 14.8-h modulation was present, and provide evidence for a similar periodicity in the 'high' state from a reanalysis of previously published photometry and spectroscopy. The presence of the same period in both states implies that it is likely to be the orbital period of the system. The spectroscopy analysis provides evidence for an apparent change in the systemic velocity of the system. The amplitude of the observed radial velocity variations, however, permits only crude limits to be placed on the mass of the compact object. Only absorption-line spectroscopy of the secondary in the 'off' state will provide a convincing mass determination.

  4. Ozone Hole Over Antarctica

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These images from the Total Ozone Mapping Spectrometer (TOMS) show the progressive depletion of ozone over Antarctica from 1979 to 1999. This 'ozone hole' has extended to cover an area as large as 10.5 million square miles in September 1998. The previous record of 10.0 million square miles was set in 1996. The Antarctic ozone hole develops each year between late August and early October. Regions with higher levels of ozone are shown in red. NASA and NOAA instruments have been measuring Antarctic ozone levels since the early 1970s. Large regions of depleted ozone began to develop over Antarctica in the early 1980s. Ozone holes of substantial size and depth are likely to continue to form during the next few years, scientists hope to see a reduction in ozone loss as levels of ozone-destroying CFCs (chlorofluorocarbons) are gradually reduced. Credit: Images by Greg Shirah, NASA Goddard Space Flight Center Scientific Visualization Studio

  5. Comparative morphometric study of the australopithecine vertebral series Stw-H8/H41.

    PubMed

    Sanders, W J

    1998-03-01

    Lower spinal structure correlates well with positional behavior among mammals. Nonetheless, the functional morphology of the axial post-crania of australopithecines has received less attention than their appendicular skeletons. This paper presents a detailed description and comparative morphometric analysis of the australopithecine thoracolumbar vertebral series Stw-H8/H41, and examines spinal mechanics in early hominids. Stw-H8/H41 is an important specimen, as the australopithecine vertebral sample is small, and vertebral series are more useful than isolated elements for the interpretation of spinal function. Results of the study support the interpretation that australopithecine species are highly sexually dimorphic. The study also reveals a considerable amount of morphometric variation other than size among australopithecine vertebrae, though the sample is too small and incomplete to ascertain whether this indicates significant interspecific differences in spinal function. Most importantly, structural and metric observations confirm that the morphology of the lower spine in australopithecines has no modern analogue in its entirety. Aspects of zygapophyseal structure, numerical composition of the lumbar region, and centrum wedging suggest that the australopithecine vertebral column was adapted to human-like intrinsic lumbar lordosis and stable balance of the trunk over the pelvis in sustained bipedal locomotion. However, relative centrum size in australopithecines indicates that either they had a different mechanism for channeling vertical forces through the vertebral column than humans, or differed behaviorally from humans in ways that produced smaller increments of compression across their centra. These findings have important implications for hypotheses of australopithecine positional behavior, and demonstrate that larger samples and more complete vertebral series are needed to improve our understanding of australopithecine spinal function. PMID:9547457

  6. Recovery of the Antarctic Ozone Hole

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph; Montzka, Steve; Schauffler, Sue; Stolarski, Richard S.; Douglass, Anne R.; Pawson, Steven; Nielsen, J. Eric

    2006-01-01

    The Antarctic ozone hole develops each year and culminates by early Spring. Antarctic ozone values have been monitored since 1979 using satellite observations from the TOMS and OMI instruments. The severity of the hole has been assessed using the minimum total ozone value from the October monthly mean (depth of the hole), the average size during the September-October period, and the ozone mass deficit. Ozone is mainly destroyed by halogen catalytic cycles, and these losses are modulated by temperature variations in the collar of the polar lower stratospheric vortex. In this presentation, we show the relationships of halogens and temperature to both the size and depth of the hole. Because atmospheric halogen levels are responding to international agreements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. We use two methods to estimate ozone hole recovery. First, we use projections of halogen levels combined with age-of-air estimates in a parametric model. Second, we use a coupled chemistry climate model to assess recovery. We find that the ozone hole is recovering at an extremely slow rate and that large ozone holes will regularly recur over the next 2 decades. Furthermore, full recovery to 1980 levels will not occur until approximately 2068. We will also show some error estimates of these dates and the impact of climate change on the recovery.

  7. When Will the Antarctic Ozone Hole Recover?

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.

    2006-01-01

    The Antarctic ozone hole develops each year and culminates by early spring (late September - early October). Antarctic ozone values have been monitored since 1979 using satellite observations from the TOMS instrument. The severity of the hole has been assessed from TOMS using the minimum total ozone value from the October monthly mean (depth of the hole) and by calculating the average area coverage during this September-October period. Ozone is mainly destroyed by halogen (chlorine and bromine) catalytic cycles, and these losses are modulated by temperature variations in the collar of the polar lower stratospheric vortex. In this talk, I will show the relationships of halogens and temperature to both the size and depth of the hole. Because atmospheric halogen levels are responding to international agreements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. Using projections of halogen levels combined with age-of-air estimates, we find that the ozone hole is recovering at an extremely slow rate and that large ozone holes will regularly recur over the next 2 decades. The ozone hole will begin to show first signs of recovery in about 2023, and the hole will fully recover to pre-1980 levels in approximately 2070. This 2070 recovery is 20 years later than recent projections. I will also discuss current assessments of mid-latitude ozone recovery.

  8. Ozone profiles above Palmer Station, Antarctica

    NASA Technical Reports Server (NTRS)

    Torres, Arnold L.; Brothers, George

    1988-01-01

    NASA's Goddard Space Flight Center/Wallops Flight Facility conducted a series of 52 balloon-borne measurements of vertical ozone profiles over the National Science Foundation (NSF) research facility at Palmer Station, Antarctica (64 deg 46 S, 64 deg 3 W) between August 9 and October 24, 1987. High resolution measurements were made from ground level to an average of 10 mb. While much variation was seen in the profile amounts of ozone, it is clear that a progressive depletion of ozone occurred during the measurement period, with maximum depletion taking place in the 17 to 19 km altitude region. Ozone partial pressures dropped by about 95 percent in this region. Shown here are plotted time dependences of ozone amounts observed at 17 km and at arbitrarily selected altitudes below (13 km) and above (24 km) the region of maximum depletion. Ozone partial pressure at 17 km is about 150nb in early August, and has decreased to less than 10nb in the minimums in October. The loss rate is of the order of 1.5 percent/day. In summary, a progressive depletion in stratospheric ozone over Palmer Station was observed from August to October, 1987. Maximum depletion occurred in the 17 to 19 km range, and amounted to 95 percent. Total ozone overburden decreased by up to 50 percent during the same period.

  9. Spatial distribution of tropospheric ozone in western Washington, USA

    USGS Publications Warehouse

    Cooper, S.M.; Peterson, D.L.

    2000-01-01

    We quantified the distribution of tropospheric ozone in topographically complex western Washington state, USA (total area a??6000 km2), using passive ozone samplers along nine river drainages to measure ozone exposure from near sea level to high-elevation mountain sites. Weekly average ozone concentrations were higher with increasing distance from the urban core and at higher elevations, increasing a mean of 1.3 ppbv per 100 m elevation gain for all mountain transects. Weekly average ozone concentrations were generally highest in Cascade Mountains drainages east and southeast of Seattle (maximum=55a??67 pbv) and in the Columbia River Gorge east of Portland (maximum=59 ppbv), and lowest in the western Olympic Peninsula (maximum=34 ppbv). Higher ozone concentrations in the Cascade Mountains and Columbia River locations downwind of large cities indicate that significant quantities of ozone and ozone precursors are being transported eastward toward rural wildland areas by prevailing westerly winds. In addition, temporal (week to week) variation in ozone distribution is synchronous within and between all drainages sampled, which indicates that there is regional coherence in air pollution detectable with weekly averages. These data provide insight on large-scale spatial variation of ozone distribution in western Washington, and will help regulatory agencies optimize future monitoring networks and identify locations where human health and natural resources could be at risk.

  10. Spatial distribution of tropospheric ozone in western Washington, USA.

    PubMed

    Cooper, S M; Peterson, D L

    2000-03-01

    We quantified the distribution of tropospheric ozone in topographically complex western Washington state, USA (total area approximately 6000 km(2)), using passive ozone samplers along nine river drainages to measure ozone exposure from near sea level to high-elevation mountain sites. Weekly average ozone concentrations were higher with increasing distance from the urban core and at higher elevations, increasing a mean of 1.3 ppbv per 100 m elevation gain for all mountain transects. Weekly average ozone concentrations were generally highest in Cascade Mountains drainages east and southeast of Seattle (maximum=55-67 pbv) and in the Columbia River Gorge east of Portland (maximum=59 ppbv), and lowest in the western Olympic Peninsula (maximum=34 ppbv). Higher ozone concentrations in the Cascade Mountains and Columbia River locations downwind of large cities indicate that significant quantities of ozone and ozone precursors are being transported eastward toward rural wildland areas by prevailing westerly winds. In addition, temporal (week to week) variation in ozone distribution is synchronous within and between all drainages sampled, which indicates that there is regional coherence in air pollution detectable with weekly averages. These data provide insight on large-scale spatial variation of ozone distribution in western Washington, and will help regulatory agencies optimize future monitoring networks and identify locations where human health and natural resources could be at risk. PMID:15092980

  11. Smoke in the City: How Often and Where Does Smoke Impact Summertime Ozone in the United States?

    PubMed

    Brey, Steven J; Fischer, Emily V

    2016-02-01

    We investigate the influence of smoke on ozone (O3) abundances over the contiguous United States. Using colocated observations of particulate matter and the National Weather Service Hazard Mapping System smoke data, we identify summertime days between 2005 and 2014 that Environmental Protection Agency Air Quality System O3 monitors are influenced by smoke. We compare O3 mixing ratio distributions for smoke-free and smoke-impacted days for each monitor, while controlling for temperature. This analysis shows that (i) the mean O3 abundance measured on smoke-impacted days is higher than on smoke-free days, and (ii) the magnitude of the effect varies by location with a range of 3 to 36 ppbv. For each site, we present the percentage of days when the 8-h average O3 mixing ratio (MDA8) exceeds 75 ppbv and smoke is present. Smoke-impacted O3 mixing ratios are most elevated in locations with the highest emissions of nitrogen oxides. The Northeast corridor, Dallas, Houston, Atlanta, Birmingham, and Kansas City stand out as having smoke present 10-20% of the days when 8-h average O3 mixing ratios exceed 75 ppbv. Most U.S. cities maintain a similar proportion of smoke-impacted exceedance days when they are held against the new MDA8 limit of 70 ppbv. PMID:26720416

  12. Interaction of ozone exposure with airway hyperresponsiveness and inflammation induced by trimellitic anhydride in sensitized guinea pigs

    SciTech Connect

    Sun, Jian; Chung, K.Fan

    1997-09-01

    The effect of prior ozone (O{sub 3}) exposure on airway hyperresponsiveness and inflammation induced by trimellitic anhydride (TMA) has been investigated in TMA-sensitized guinea pigs. Airway responsiveness was measured as the concentration of acetylcholine needed to increase baseline lung resistance (RL) by 300% (PC300). Ozone (3 ppm, for 3 h) caused an increase in-log PC300 at 1 h after exposure, with return of -log PC300 to control levels at 8 h. Ozone also increased baseline RL at 8 h. TMA challenge increase -log PC300 in TMA-sensitized guinea pigs at 8 h after challenge from 3.85 {+-} 0.09 to 4.11 {+-} 0.09. Ozone exposure prior to TMA challenge prevented the induction of airway hyperresponsiveness with a mean -log PC300 of 3.51 {+-} 0.20, which was not different from that of control TMA-Sensitized group. Baseline RL was significantly higher in ozone-pretreated animals after TMA challenge when compared to those of either control or challenged with TMA alone. Ozone had no effect on TMA challenge-induced BAL eosinophilia and neutrophilia. We conclude that a single exposure to ozone inhibits the increase in airway responsiveness, but increases the bronchoconstrictor response induced by TMA in TMA-Sensitized guinea pigs; however, the inflammatory airway response to TMA is unchanged by preexposure to ozone. 29 refs., 2 figs., 1 tab.

  13. [Ozone decline and UV increase].

    PubMed

    Winkler, P; Trepte, S

    2004-02-01

    The following results have been obtained from long-term observations on the ozone layer and UV at the Meteorological Observatory Hohenpeigenberg:The seasonally varying decline of the ozone layer determines the maximum exposure to UV. Since ozone decline shows the highest rates in the spring months the UV exposure has most strongly increased in this time of the year. This is especially important because in spring the human skin is not adapted to UV exposure. Weather changes from day to day can induce rapid ozone reductions in spring about -30% which in turn is followed by an increase in UV of about 40%. Clouds, especially the transparent cirrus clouds (high clouds consisting of ice particles) have increased in frequency during spring and fall while a decrease is observed in summer. This change in cloudiness reduces the daily UV dose in spring and fall while it is enhanced in summer. With increasing height above sea level UV rises by roughly 10% per 1000 m (rule of thumb). Snow reflects the UV-radiation by up to 80% enhancing the UV-doses at relevant conditions. Strong volcano eruptions destroy ozone in the stratosphere additionally during 1-2 years after the eruption. Therafter the ozone layer recovers. In April 1993, after the eruption of Mt. Pinatubo (1991), the UV burden was still 40% higher than average. Miniholes and streamers can appear unexpected on a short-time scale and cross over Central Europe within 1-2 days, thus enhancing UV irradiation. The human skin reacts to UV exposure depending on the type of skin. The campaign "Sonne(n) mit Verstand" of the Bavarian Ministries for Environment, for Health and for Education informs about the danger of UV radiation (see www.sonne-mit-ver-stand.de). The German Weather Service informs the public on present developments of the ozone layer and relevant topics byits ozone bulletin, which is also available via internet under (www.dwd.de/deFundE/Observator/MOHp/hp2/ozon/bulletin.htm). PMID:14770335

  14. Surface ozone concentrations in Agra: links with the prevailing meteorological parameters

    NASA Astrophysics Data System (ADS)

    Singla, Vyoma; Pachauri, Tripti; Satsangi, Aparna; Kumari, K. Maharaj; Lakhani, Anita

    2012-12-01

    Measurements of surface ozone (O3), nitric oxide (NO), nitrogen dioxide (NO2), oxides of nitrogen (NOx=NO+NO2) and meteorological parameters have been made at Agra (North Central India, 27°10'N, 78°05'E) in post monsoon and winter season. The diurnal variation in O3 concentration shows daytime in situ photochemical production with diurnal maximum in noon hours ranging from 51 to 54 ppb in post monsoon and from 76 to 82 ppb in winter, while minimum (16-24 ppb) during nighttime and early morning hours. Average 8-h O3 concentration varied from 12.4 to 83.9 ppb. The relationship between meteorological parameters (solar radiation intensity, temperature, relative humidity, wind speed and wind direction) and surface O3 variability was studied using principal component analysis (PCA), multiple linear regression (MLR) and correlation analysis (CA). PCA and MLR of daily mean O3 concentrations on meteorological parameters explain up to 80 % of day to day ozone variability. Correlation with meteorology is strongly emphasized on days having strong solar radiation intensity and longer sunshine time.

  15. Meteorology-induced variations in the spatial behavior of summer ozone pollution in Central California

    SciTech Connect

    Jin, Ling; Harley, Robert A.; Brown, Nancy J.

    2010-06-23

    Cluster analysis was applied to daily 8 h ozone maxima modeled for a summer season to characterize meteorology-induced variations in the spatial distribution of ozone. Principal component analysis is employed to form a reduced dimension set to describe and interpret ozone spatial patterns. The first three principal components (PCs) capture {approx}85% of total variance, with PC1 describing a general spatial trend, and PC2 and PC3 each describing a spatial contrast. Six clusters were identified for California's San Joaquin Valley (SJV) with two low, three moderate, and one high-ozone cluster. The moderate ozone clusters are distinguished by elevated ozone levels in different parts of the valley: northern, western, and eastern, respectively. The SJV ozone clusters have stronger coupling with the San Francisco Bay area (SFB) than with the Sacramento Valley (SV). Variations in ozone spatial distributions induced by anthropogenic emission changes are small relative to the overall variations in ozone amomalies observed for the whole summer. Ozone regimes identified here are mostly determined by the direct and indirect meteorological effects. Existing measurement sites are sufficiently representative to capture ozone spatial patterns in the SFB and SV, but the western side of the SJV is under-sampled.

  16. Four Summers of Ozone Profiles Over Beltsville, MD: A Study of Free-Tropospheric and Boundary Layer Ozone

    NASA Astrophysics Data System (ADS)

    Yorks, J. E.; Thompson, A. M.; Ryan, W. F.; Taubman, B. F.; Joseph, E.; Voemel, H.; Bojkov, B.; McQueen, J.

    2007-12-01

    A total of over 75 ozonesonde launches were made in Beltsville, MD during the summers of 2004 through 2007 as part of 4 different field campaigns; INTEX Ozonesonde Network Study 2004 (IONS-04, http://croc.gsfc.nasa.gov/intex/ions.html), Howard/NCAS ozonesondes for MDE (Maryland Department of the Environment) Pollution Episodes (http://www.physics1.howard.edu), and the Water Vapor Validation Experiment - Satellite/Sondes 2006 & 2007 (WAVES, http://ecotronics.com/lidar-misc/WAVES.htm). These profiles were used to characterize variability in sources of tropospheric ozone. On average, free-tropospheric ozone was composed of the following: 10% regional convection and lightning-derived NO, 25% stratospheric ozone, with the balance (~65%) a mixture of aged air of indeterminate origin and recently advected ozone. A separate analysis of local emission and boundary layer ozone was performed. The data from 2005 and 2006 includes both nighttime and daytime launches, permitting an investigation between planetary boundary layer processes and surface ozone. In nighttime profiles with above average column ozone in the residual layer, daily maximum 1 hr and 8 hr average surface ozone values were roughly 10 to 15 ppbv greater than days with below average column ozone in the residual layer. These results, as well as vertical profiles, were compared to the NOAA/EPA Operational Air Quality Model forecasts for Beltsville. The model showed a highly negative bias for maximum 1 hr ozone values, but only a slightly negative bias for maximum 8 hr ozone values on days with above average residual layer ozone.

  17. Ozone depletion at northern and southern latitudes derived from January 1979 to December 1991 Total Ozone Mapping Spectrometer data

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Mcpeters, R.; Larko, D.

    1993-01-01

    An extended version of the Nimbus 7/TOMS ozone data set from the period January 1, 1979 to December 31, 1991 is presented. It is shown that the ozone-trend data indicate that regions of enhanced ozone depletion rates have formed at middle and high latitudes during recent years. The seasonal dependence and geographical extent of the enhanced ozone-depletion rates for the Northern and Southern hemispheres are examined. The variability of the long-term ozone trend determination is discussed via consideration of the differences among 11-, 12-, and 13-yr trend calculations. The effects of the Mount Pinatubo eruption and other volcanic eruptions on the TOMS equatorial zonal average ozone measurements, and its influence on long-term trend determinations are discussed. On the basis of a determination of the aerosol phase function using TOMS data, the effect of stratospheric aerosols on determination of ozone amounts from TOMS are shown to be less than 1 percent.

  18. Bonding in Complexes of Bis(pentalene)dititanium, Ti2(C8H6)2

    PubMed Central

    2015-01-01

    Bonding in the bis(pentalene)dititanium “double-sandwich” species Ti2Pn2 (Pn = C8H6) and its interaction with other fragments have been investigated by density functional calculations and fragment analysis. Ti2Pn2 with C2v symmetry has two metal–metal bonds and a low-lying metal-based empty orbital, all three frontier orbitals having a1 symmetry. The latter may be regarded as being derived by symmetric combinations of the classic three frontier orbitals of two bent bis(cyclopentadienyl) metal fragments. Electrochemical studies on Ti2Pn†2 (Pn† = 1,4-{SiiPr3}2C8H4) revealed a one-electron oxidation, and the formally mixed-valence Ti(II)–Ti(III) cationic complex [Ti2Pn†2][B(C6F5)4] has been structurally characterized. Theory indicates an S = 1/2 ground-state electronic configuration for the latter, which was confirmed by EPR spectroscopy and SQUID magnetometry. Carbon dioxide binds symmetrically to Ti2Pn2, preserving the C2v symmetry, as does carbon disulfide. The dominant interaction in Ti2Pn2CO2 is σ donation into the LUMO of bent CO2, and donation from the O atoms to Ti2Pn2 is minimal, whereas in Ti2Pn2CS2 there is significant interaction with the S atoms. The bridging O atom in the mono(oxo) species Ti2Pn2O, however, employs all three O 2p orbitals in binding and competes strongly with Pn, leading to weaker binding of the carbocyclic ligand, and the sulfur analogue Ti2Pn2S behaves similarly. Ti2Pn2 is also capable of binding one, two, or three molecules of carbon monoxide. The bonding demands of a single CO molecule are incompatible with symmetric binding, and an asymmetric structure is found. The dicarbonyl adduct Ti2Pn2(CO)2 has Cs symmetry with the Ti2Pn2 unit acting as two MCp2 fragments. Synthetic studies showed that in the presence of excess CO the tricarbonyl complex Ti2Pn†2(CO)3 is formed, which optimizes to an asymmetric structure with one semibridging and two terminal CO ligands. Low-temperature 13C NMR spectroscopy revealed a rapid

  19. An overview of the 2013 Las Vegas Ozone Study (LVOS): Impact of stratospheric intrusions and long-range transport on surface air quality

    NASA Astrophysics Data System (ADS)

    Langford, A. O.; Senff, C. J.; Alvarez, R. J.; Brioude, J.; Cooper, O. R.; Holloway, J. S.; Lin, M. Y.; Marchbanks, R. D.; Pierce, R. B.; Sandberg, S. P.; Weickmann, A. M.; Williams, E. J.

    2015-05-01

    The 2013 Las Vegas Ozone Study (LVOS) was conducted in the late spring and early summer of 2013 to assess the seasonal contribution of stratosphere-to-troposphere transport (STT) and long-range transport to surface ozone in Clark County, Nevada and determine if these processes directly contribute to exceedances of the National Ambient Air Quality Standard (NAAQS) in this area. Secondary goals included the characterization of local ozone production, regional transport from the Los Angeles Basin, and impacts from wildfires. The LVOS measurement campaign took place at a former U.S. Air Force radar station ∼45 km northwest of Las Vegas on Angel Peak (∼2.7 km above mean sea level, asl) in the Spring Mountains. The study consisted of two extended periods (May 19-June 4 and June 22-28, 2013) with near daily 5-min averaged lidar measurements of ozone and backscatter profiles from the surface to ∼2.5 km above ground level (∼5.2 km asl), and continuous in situ measurements (May 20-June 28) of O3, CO, (1-min) and meteorological parameters (5-min) at the surface. These activities were guided by forecasts and analyses from the FLEXPART (FLEXible PARTticle) dispersion model and the Real Time Air Quality Modeling System (RAQMS), and the NOAA Geophysical Research Laboratory (NOAA GFDL) AM3 chemistry-climate model. In this paper, we describe the LVOS measurements and present an overview of the results. The combined measurements and model analyses show that STT directly contributed to each of the three O3 exceedances that occurred in Clark County during LVOS, with contributions to 8-h surface concentrations in excess of 30 ppbv on each of these days. The analyses show that long-range transport from Asia made smaller contributions (<10 ppbv) to surface O3 during two of those exceedances. The contribution of regional wildfires to surface O3 during the three LVOS exceedance events was found to be negligible, but wildfires were found to be a major factor during exceedance events

  20. Synthesis, High-Resolution Infrared Spectroscopy, and Vibrational Structure of Cubane, C8H8.

    PubMed

    Boudon, V; Lamy, M; Dugue-Boyé, F; Pirali, O; Gruet, S; D'Accolti, L; Fusco, C; Annese, C; Alikhani, M E

    2016-06-30

    Carbon-cage molecules have generated a considerable interest from both experimental and theoretical points of view. We recently performed a high-resolution study of adamantane (C10H16), the smallest hydrocarbon cage belonging to the diamandoid family ( Pirali , O. ; et al. J. Chem. Phys. 2012 , 136 , 024310 ). There exist another family of hydrocarbon cages with additional interesting chemical properties: the so-called platonic hydrocarbons that comprise dodecahedrane (C20H20) and cubane (C8H8). Both possess C-C bond angles that deviate from the tetrahedral angle (109.8°) of the sp(3) hybridized form of carbon. This generates a considerable strain in the molecule. We report a new wide-range high-resolution study of the infrared spectrum of cubane. The sample was synthesized in Bari upon decarboxylation of 1,4-cubanedicarboxylic acid thanks to the improved synthesis of literature. Several spectra have been recorded at the AILES beamline of the SOLEIL synchrotron facility. They cover the 600-3200 cm(-1) region. Besides the three infrared-active fundamentals (ν10, ν11, and ν12), we could record many combination bands, all of them displaying a well-resolved octahedral rotational structure. We present here a preliminary analysis of some of the recorded bands, performed thanks the SPVIEW and XTDS software, based on the tensorial formalism developed in the Dijon group. A comparison with ab initio calculations, allowing to identify some combination bands, is also presented. PMID:27267150

  1. Options to accelerate ozone recovery:ozone and climate benefits

    NASA Astrophysics Data System (ADS)

    Daniel, J. S.; Fleming, E. L.; Portmann, R. W.; Velders, G. J. M.; Jackman, C. H.; Ravishankara, A. R.

    2010-04-01

    Hypothetical reductions in future emissions of ozone-depleting substances (ODSs), including N2O, are evaluated in terms of effects on equivalent effective stratospheric chlorine (EESC), globally-averaged total column ozone, and radiative forcing through 2100. Due to the established success of the Montreal Protocol, these actions can have only a fraction of the impact that regulations already in force have had. If all anthropogenic ODS emissions were halted beginning in 2011, ozone is calculated to be higher by about 1-2{%} during the period 2030-2100 compared to a case of no additional ODS restrictions. Radiative forcing by 2100 would be about 0.23 W/m2 lower due to the elimination of N2O emissions and about 0.005 W/m2 lower due to destruction of the chlorofluorocarbon (CFC) bank. The ability of EESC to be a suitable metric for total ozone is also quantified. Responding to the recent suggestion that N2O should be considered an ODS, we provide an approach to incorporate N2O into the EESC formulation.

  2. Ozone’s Impact on Public Health: Contributions from Indoor Exposures to Ozone and Products of Ozone-Initiated Chemistry

    PubMed Central

    Weschler, Charles J.

    2006-01-01

    Objective The associations between ozone concentrations measured outdoors and both morbidity and mortality may be partially due to indoor exposures to ozone and ozone-initiated oxidation products. In this article I examine the contributions of such indoor exposures to overall ozone-related health effects by extensive review of the literature as well as further analyses of published data. Findings Daily inhalation intakes of indoor ozone (micrograms per day) are estimated to be between 25 and 60% of total daily ozone intake. This is especially noteworthy in light of recent work indicating little, if any, threshold for ozone’s impact on mortality. Additionally, the present study estimates that average daily indoor intakes of ozone oxidation products are roughly one-third to twice the indoor inhalation intake of ozone alone. Some of these oxidation products are known or suspected to adversely affect human health (e.g., formaldehyde, acrolein, hydroperoxides, fine and ultrafine particles). Indirect evidence supports connections between morbidity/mortality and exposures to indoor ozone and its oxidation products. For example, cities with stronger associations between outdoor ozone and mortality tend to have residences that are older and less likely to have central air conditioning, which implies greater transport of ozone from outdoors to indoors. Conclusions Indoor exposures to ozone and its oxidation products can be reduced by filtering ozone from ventilation air and limiting the indoor use of products and materials whose emissions react with ozone. Such steps might be especially valuable in schools, hospitals, and childcare centers in regions that routinely experience elevated outdoor ozone concentrations. PMID:17035131

  3. Higher Surface Ozone Concentrations Over the Chesapeake Bay than Over the Adjacent Land: Observations and Models from the DISCOVER-AQ and CBODAQ Campaigns

    NASA Technical Reports Server (NTRS)

    Goldberg, Daniel L.; Loughner, Christopher P.; Tzortziou, Maria; Stehr, Jeffrey W.; Pickering, Kenneth E.; Marufu, Lackson T.; Dickerson, Russell R.

    2013-01-01

    Air quality models, such as the Community Multiscale Air Quality (CMAQ) model, indicate decidedly higher ozone near the surface of large interior water bodies, such as the Great Lakes and Chesapeake Bay. In order to test the validity of the model output, we performed surface measurements of ozone (O3) and total reactive nitrogen (NOy) on the 26-m Delaware II NOAA Small Research Vessel experimental (SRVx), deployed in the Chesapeake Bay for 10 daytime cruises in July 2011 as part of NASA's GEO-CAPE CBODAQ oceanographic field campaign in conjunction with NASA's DISCOVER-AQ air quality field campaign. During this 10-day period, the EPA O3 regulatory standard of 75 ppbv averaged over an 8-h period was exceeded four times over water while ground stations in the area only exceeded the standard at most twice. This suggests that on days when the Baltimore/Washington region is in compliance with the EPA standard, air quality over the Chesapeake Bay might exceed the EPA standard. Ozone observations over the bay during the afternoon were consistently 10-20% higher than the closest upwind ground sites during the 10-day campaign; this pattern persisted during good and poor air quality days. A lower boundary layer, reduced cloud cover, slower dry deposition rates, and other lesser mechanisms, contribute to the local maximum of ozone over the Chesapeake Bay. Observations from this campaign were compared to a CMAQ simulation at 1.33 km resolution. The model is able to predict the regional maximum of ozone over the Chesapeake Bay accurately, but NOy concentrations are significantly overestimated. Explanations for the overestimation of NOy in the model simulations are also explored

  4. When Will the Antarctic Ozone Hole Recover?

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph; Montzka, Steve

    2005-01-01

    The Antarctic ozone hole develops each year and culminates by early Spring. Antarctic ozone values have been monitored since 1979 using satellite observations from the TOMS instrument. The severity of the hole has been assessed from TOMS using the minimum total ozone value from the October monthly mean (depth of the hole) and by calculating the average size during the September-October period. Ozone is mainly destroyed by halogen catalytic cycles, and these losses are modulated by temperature variations in the collar of the polar lower stratospheric vortex. In this presentation, we show the relationships of halogens and temperature to both the size and depth of the hole. Because atmospheric halogen levels are responding to international agreements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. Using projections of halogen levels combined with age-of-air estimates, we find that the ozone hole is recovering at an extremely slow rate and that large ozone holes will regularly recur over the next 2 decades. We will show estimates of both when the ozone hole will begin to show first signs of recovery, and when the hole will fully recover to pre-1980 levels.

  5. When will the Antarctic Ozone Hole Recover?

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph; Montzka, Steve

    2006-01-01

    The Antarctic ozone hole develops each year and culminates by early Spring. Antarctic ozone values have been monitored since 1979 using satellite observations from the .TOMS instrument. The severity of the hole has been assessed from TOMS using the minimum total ozone value from the October monthly mean (depth of the hole) and by calculating the average size during the September-October period. Ozone is mainly destroyed by halogen catalytic cycles, and these losses are modulated by temperature variations in the collar of the polar lower stratospheric vortex. In this presentation, we show the relationships of halogens and temperature to, both the size and depth of the hole. Because atmospheric halogen levels are responding to international agreements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. Using projections of halogen levels combined with age-of-air estimates, we find that the ozone hole is recovering at an extremely slow rate and that large ozone holes will regularly recur over the next 2 decades. The ozone hole will begin to show first signs of recovery in about 2023, and the hole will fully recover to pre-1980 levels in approximately 2070. This 2070 recovery is 20 years later than recent projections.

  6. Aircraft cabin ozone measurements on B747-100 and B747-SP aircraft: Correlations with atmospheric ozone and ozone encounter statistics

    NASA Technical Reports Server (NTRS)

    Perkins, P. J.; Holdeman, J. D.; Gauntner, D. J.

    1978-01-01

    Simultaneous measurements of atmospheric (outside) ozone concentration and ozone levels in the cabin of the B747-100 and B747-SP airliners were made by NASA to evaluate the aircraft cabin ozone contamination problem. Instrumentation on these aircraft measured ozone from an outside probe and at one point in the cabin. Average ozone in the cabin of the B747-100 was 39 percent of the outside. Ozone in the cabin of the B747-SP measured 82 percent of the outside, before corrective measures. Procedures to reduce the ozone in this aircraft included changes in the cabin air circulation system, use of the high-temperature 15th stage compressor bleed, and charcoal filters in the inlet cabin air ducting, which as separate actions reduced the ozone to 58, 19 and 5 percent, respectively. The potential for the NASA instrumented B747 aircraft to encounter high levels of cabin ozone was derived from atmospheric oxone measurements on these aircraft. Encounter frequencies for two B747-100's were comparable even though the route structures were different. The B747-SP encountered high ozone than did the B747-100's.

  7. Ozone in the free atmosphere

    NASA Technical Reports Server (NTRS)

    Whitten, R. C. (Editor); Prasad, S. S. (Editor)

    1985-01-01

    The present book provides a summary of the state of scientific knowledge of stratospheric and free tropospheric ozone as it exists at the beginning of 1983. Ozone photochemistry in the stratosphere is discussed, taking into account fundamental molecular properties, the absorption spectrum of ozone, photodissociation, ozone formation and destruction in the upper atmosphere, the photochemistry of odd-hydrogen, the photochemistry of odd-nitrogen, the photochemistry of odd-chlorine, and photochemistry-temperature coupling. The observed distribution of atmospheric ozone and its variations are considered along with ozone transport, ozone in the troposphere, stratospheric ozone perturbations, and climatic and biological effects. Attention is given to the techniques of observing atmospheric ozone, horizontal-vertical ozone transport and conservative quantities, measurements of tropospheric ozone, the tropospheric ozone budget, ozone models, natural ozone variations, and anthropogenic ozone perturbations.

  8. Sequential Camouflage of the arachno-6,9-C2B8H14 Cage by Substituents.

    PubMed

    Bakardjiev, Mario; Štíbr, Bohumil; Holub, Josef; Tok, Oleg L; Švec, Petr; Růžičková, Zdeňka; Růžička, Aleš

    2016-07-18

    Sequential methylation of arachno-6,9-C2B8H14 (1) led to a series of methyl derivatives and finally to the camouflaging of all boron positions by mixed persubstitution. Thus, deprotonation of 1 produced the [arachno-6,9-C2B8H13] anion (1(-)), the methylation of which with MeI in tetrahydrofuran proceeded on the open-face boron vertexes with the formation of 5-Me-arachno-6,9-C2B8H13 (2; yield 28%) and 5,8-Me2-arachno-6,9-C2B8H12 (3; yield 36%). Observed in this reaction was also a side formation of 2-Me-closo-1,6-C2B8H9 (4; yield 6%).The electrophilic AlCl3-catalyzed CH3(+) attack of the neutral 1 in neat MeI at ambient temperature afforded 1,3-Me2-arachno-6,9-C2B8H12 (5), while a 76-h heating at 120 °C generated a mixture of the di- and triiodo derivatives 1,2,3,4,8,10-Me6-5,7-I2-arachno-6,9-C2B8H6 (6) and 1,2,3,4,7-Me5-5,7,10-I3-arachno-6,9-C2B8H6 (7). On the other hand, a HOTf-catalyzed reaction between 1 and MeOTf at reflux resulted in the isolation of 2-TfO-1,3.4,5,7,8,10-Me7-arachno-6,9-C2B8H6 (8; Tf = CF3SO2; yield 65%). The compounds were characterized by multinuclear ((11)B, (1)H, (13)C, and (19)F) NMR spectroscopy, mass spectrometry, and elemental analysis, and the structures of compounds 1, 1(-), 5, and 6 were established by X-ray diffraction analysis. PMID:27351461

  9. Ozone Trend Detectability

    NASA Technical Reports Server (NTRS)

    Campbell, J. W. (Editor)

    1981-01-01

    The detection of anthropogenic disturbances in the Earth's ozone layer was studied. Two topics were addressed: (1) the level at which a trend in total ozoning is detected by existing data sources; and (2) empirical evidence in the prediction of the depletion in total ozone. Error sources are identified. The predictability of climatological series, whether empirical models can be trusted, and how errors in the Dobson total ozone data impact trend detectability, are discussed.

  10. Observations of the 1995 ozone hole over Punta Arenas, Chile

    NASA Astrophysics Data System (ADS)

    Kirchhoff, V. W. J. H.; Sahai, Y.; Casiccia, C. A. R. S.; Zamorano, B. F.; Valderrama, V. V.

    1997-07-01

    We examine the appearance of the ozone hole over a populated area with more than 100,000 inhabitants. The largest population concentrations on the South American continent nearest the ozone hole region are Punta Arenas, Chile (53.0°S, 70.9°W) and Ushuaia, Argentina (54.5°S, 68.0°W), located close to the strait of Magallanes, opposite the Antarctic Peninsula. A special field mission was held in Punta Arenas, in September-October 1995 to investigate the vertical distribution of ozone during the appearance of the Antarctic ozone hole. Previous work has shown that the city of Punta Arenas is located at the edge of the hole area and is affected every year during a few days in the October period. The ozone trend near these locations is -0.5% per year using the yearly averages and -1.2% per year using the October means. This trend is 2 to 5 times larger than the global average. Several ozonesondes of the electrochemical concentration cell type were launched from Punta Arenas to determine the vertical distribution of ozone during "normal" and "perturbed" conditions. The ozone hole passed over Punta Arenas on October 12, 13 and 14, 1995. In addition to the sondes, which were launched once a day, ozone column amounts and UVB radiation were measured with a ground-based ozone Brewer spectrophotometer. The strongest ozone depletion over Punta Arenas in 1995 occurred on October 13, when the ozone column decreased from a "normal" value of about 325 Dobson Units (DU) to 200 DU; the vertical distribution of ozone on October 13 compared with October 6 shows depleted ozone roughly 50% less during hole conditions in the stratosphere. The UVB intensities have increased accordingly. The spectral ratio for October 13 to October 4 is 13 times larger at 297 nm.

  11. 8 HOUR OZONE DESIGN VALUE FOR 1998-2000

    EPA Science Inventory

    The Ozone design value is based on the average of the annual 4th highest dailsy 8-hour maximum over a 3-year period (1998-2000) in this case. This is a human health based metric. Ozone causes respiratory illness in humans.

  12. Structural changes in wood during ozonation

    NASA Astrophysics Data System (ADS)

    Ben'ko, E. M.; Manisova, O. R.; Murav'eva, G. P.; Lunin, V. V.

    2013-07-01

    It is found that ozone treatment of aspen wood leads to changes in its structural characteristics, i.e., its specific surface area and the crystallinity index of cellulose. Using optical microscopy, it is shown that ozonation is accompanied by a decrease in the average size and visible surface of wood particles. The values for the specific area of the outer surface of samples are calculated. The specific surface area available to the enzyme molecules is determined from data on the adsorption of inert protein hemoglobin on wood. It is shown that this value is an order of magnitude higher than that of the outer surface and increases considerably for an ozonized sample. Based on the results from X-ray analysis, it is established that the structure of cellulose is disordered during ozone delignification, as is indicated by a reduction in the crystallinity index and crystallite sizes.

  13. Nqrs Data for C8H5Li2O4.5 [C8H4Li2O4·1/2(H2O)] (Subst. No. 1059)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H5Li2O4.5 [C8H4Li2O4·1/2(H2O)] (Subst. No. 1059)

  14. Click Dehydrogenation of Carbon-Substituted nido-5,6-C2B8H12 Carboranes: A General Route to closo-1,2-C2B8H10 Derivatives.

    PubMed

    Tok, Oleg L; Bakardjiev, Mario; Štíbr, Bohumil; Hnyk, Drahomír; Holub, Josef; Padělková, Zdenka; Růžička, Aleš

    2016-09-01

    Triethylamine-catalyzed dehydrogenation of carbon-disubstituted dicarbaboranes 5,6-R2-nido-5,6-C2B8H10 [1, where R = H (1a), Me (1b), and Ph (1c)] in refluxing acetonitrile leads to a high-yield (up to 85-95%) formation of a series of dicarbaboranes 1,2-R2-closo-1,2-C2B8H8 (2). The monosubstituted 6-R-nido-5,6-C2B8H11 (3) analogues [where R = Ph (3a), naph (1-naphthyl; 3b), Bu (3c)] afforded 1-R-1,2-closo C2B8H9 (4) isomers [where R = Ph (4a), naph (4b), n-Bu (4c)] as the main products; compounds 4a and 4c were accompanied by 2-R-1,2-C2B8H9 (5) isomers (total yields up to 90%), with the 4/5 molar ratio being strongly dependent on the nature of R (4:1 and 1:1, respectively). All of these cage-closure reactions are supposed to proceed via the stage of the corresponding Et3NH(+) salts of nido anions [5,6-R2-5,6-C2B8H9](-) (1(-)) and [6-R-5,6-C2B8H10](-) (3(-)), which lose H2 and Et3N upon heating (dehydrodeamination). The cage-closure mechanisms leading to closo isomers 2, 4, and 5 have been substantiated by B3LYP/6-31+G* calculations of the reaction profile for a simple 1a(-) → 2a + H(-) conversion. All of the compounds isolated have been characterized by multinuclear ((11)B, (1)H, and (13)C) NMR spectroscopy, mass spectrometry, and elemental analyses, and the structure of 1-Ph-closo-1,2-C2B8H9 (4a) was established by an X-ray diffraction study. PMID:27551885

  15. Contributions of regional air pollutant emissions to ozone and fine particulate matter-related mortalities in eastern U.S. urban areas.

    PubMed

    Hou, Xiangting; Strickland, Matthew J; Liao, Kuo-Jen

    2015-02-01

    Ground-level ozone and fine particulate matter (PM2.5) are associated with adverse human health effects such as lung structure dysfunction, inflammation and infection, asthma, and premature deaths. This study estimated contributions of emissions of anthropogenic nitrogen oxides (NOx), volatile organic compounds (VOCs) and sulfur dioxides (SO2) from four regions to summertime (i.e., June, July, and August) ozone and PM2.5-related mortalities in seven major Metropolitan Statistical Areas (MSAs with more than 4 million people) in the eastern United States (U.S.). A photochemical transport model, Community Multi-scale Air Quality (CMAQ) with sensitivity analyses, was applied to quantify the contribution of the regional anthropogenic emissions to ambient ozone and PM2.5 concentrations in the seven MSAs. The results of the sensitivity analysis, along with estimates of concentration-response from published epidemiologic studies, were used to estimate excess deaths associated with changes in ambient daily 8-h average ozone and daily PM2.5 concentrations during the summer of 2007. The results show that secondary PM2.5 (i.e., PM2.5 formed in the atmosphere) had larger effects on mortality (95% confidence interval (C.I.) ranged from 700 to 3854) than ambient ozone did (95% C.I. was 470-1353) in the seven MSAs. Emissions of anthropogenic NOx, VOCs and SO2 from the northeastern U.S. could cause up to about 2500 ozone and PM2.5-related deaths in the urban areas examined in this study. The results also show that the contributions of emissions from electrical generating units (EGUs) and anthropogenic non-EGU sources to ozone-related mortality in the MSAs were similar. However, emissions from EGUs had a more significant impact on PM2.5-related deaths than anthropogenic emissions from non-EGUs sources did. Anthropogenic NOx and VOCs emissions from the regions where the MSAs are located had the most significant contributions to ozone-related mortalities in the eastern U.S. urban

  16. 2001 OZONE DESIGN VALUE

    EPA Science Inventory

    Ozone is generated by a complex atmoshperic chemical process. Industrial and automobile pollutants in the form of oxides of nitrogen and hydrocarbons react in the atmosphere when air is stagnant and temperatures are high to form ozone. Ozone is known to cause adverse health eff...

  17. 2020 OZONE DESIGN VALUE

    EPA Science Inventory

    Ozone is generated by a complex atmoshperic chemical process. Industrial and automobile pollutants in the form of oxides of nitrogen and hydrocarbons react in the atmosphere when air is stagnant and temperatures are high to form ozone. Ozone is known to cause adverse health eff...

  18. OZONE BYPRODUCT FORMATION

    EPA Science Inventory

    The use of ozone for water treatment has been increasing as ozone has great potential for degrading water pollutants and inactivating viruses, Giardia cysts, and Cryptosporidium oocysts. Although it appears that ozone generates less undesirable disinfection by-products (DBPs) th...

  19. Ozone Antimicrobial Efficacy

    EPA Science Inventory

    Ozone is a potent germicide that has been used extensively for water purification. In Europe, 90 percent of the municipal water systems are treated with ozone, and in France, ozone has been used to treat drinking water since 1903. However, there is limited information on the bioc...

  20. Monitoring and future projections of the Antarctic Ozone Hole using the new Ozone Mapping and Profiler Suite (OMPS)

    NASA Astrophysics Data System (ADS)

    Kramarova, N. A.; Newman, P. A.; Nash, E. R.; Bhartia, P. K.; McPeters, R. D.; Rault, D. F.; Seftor, C. J.; Xu, P.

    2013-12-01

    Using the new Ozone Mapping and Profiler Suite (OMPS), launched October 2011 on board the Suomi National Polar-orbiting Partnership satellite, we have studied the structure and evolution of the 2012 and 2013 ozone holes. The 1st ozone hole observations by OMPS began in 2012. We quality check the OMPS measurements by comparing to other satellite instruments (Aura MLS, OMI and SBUV) and ozone sonde balloon measurements. The comparisons reveal that OMPS is producing excellent Antarctic ozone hole information, and, thus, OMPS data can be used to continue the historical record of Antarctic ozone observations. In 2012 the ozone hole developed quite normally in the August to-late September 2012 period, but disappeared much more rapidly during the late-September to November period than it would be expected in a normal year. This resulted in the second weakest ozone hole observed since 1988. Some have suggested that the rapid 2012 disappearance is evidence that the Montreal Protocol is working. However, the development of the ozone hole in August and September is largely driven by chlorine and bromine from human-produced compounds, and the normal development of the ozone hole in August-September 2012 suggests that chlorine and bromine levels were roughly the same as previous years. At the same time, observations from meteorological data show that there were stronger than average weather systems, faster warming during the September -November period, and stronger vertical motions, that led to a rapid decay of the 2012 ozone hole. Hence, the weak ozone hole of 2012 is not evidence that the Montreal Protocol has impacted the ozone hole. The characteristics of the 2013 ozone hole, as observed by OMPS, will also be shown in the presentation. Model predictions suggest that the ozone hole will begin showing signs of recovery in about 2018, and it will be fully recovered back to 1980 levels in about 2065. We will update projections of the ozone hole recovery using a parametric model

  1. The origin of ozone

    NASA Astrophysics Data System (ADS)

    Grewe, V.

    2006-05-01

    Highest atmospheric ozone production rates can be found at around 30 km in the tropical stratosphere, leading to ozone mixing ratios of about 10 ppmv. Those stratospheric air masses are then transported to extra-tropical latitudes via the Brewer-Dobson circulation. This is considered the main mechanism to generate mid- and high latitude ozone. By applying the climate-chemistry models E39/C and MAECHAM4/CHEM, this view is investigated in more detail. The origin of ozone in the troposphere and stratosphere is analysed, by incorporating a diagnostics ("marked ozone origin tracers") into the models, which allows to identify the origin of ozone. In most regions the simulated local ozone concentration is dominated by local ozone production, i.e. less than 50% of the ozone at higher latitudes of the stratosphere is produced in the tropics, which conflicts with the idea that the tropics are the global source for stratospheric ozone. Although episodic stratospheric intrusions occur basically everywhere, the main ozone stratosphere-to-troposphere exchange is connected to exchange processes at the sub-tropical jet-stream. The simulated tropospheric influx of ozone amounts to 420 Tg per year, and originates in the Northern Hemisphere from the extra-tropical stratosphere, whereas in the Southern Hemisphere a re-circulation of tropical tropospheric ozone contributes most to the influx of ozone into the troposphere. In the model E39/C, the upper troposphere of both hemispheres is clearly dominated by tropical tropospheric ozone (40%-50%) except for northern summer hemisphere, where the tropospheric contribution (from the tropics as well as from the Northern Hemisphere) does not exceed 20%.

  2. High-Resolution Infrared Spectroscopy of Cubane, C_8H_8

    NASA Astrophysics Data System (ADS)

    Boudon, Vincent; Pirali, Olivier; Gruet, Sébastien; D'accolti, Lucia; Fusco, Caterina; Annese, Cosimo

    2014-06-01

    Carbon-cage molecules have generated a considerable interest from both experimental and theoretical point of views. We recently performed a high-resolution study of adamantane (C10H16), the smallest hydrocarbon cage belonging to the diamandoid family. There exist another family of hydrocarbon cages with additional interesting chemical properties: the so-called Platonic hydrocarbons that comprise dodecahedrane (C20H20) and cubane (C_8H_8). Both possess C-C bond angles that deviate from the tetrahedral angle (109.8°) of the sp^3 hybridized form of carbon. This generates a considerable strain in the molecule. Cubane itself has the highest density of all hydrocarbons (1.29 g/cm^3). This makes it able to store larges amounts of energy, although the molecule is fully stable. Up to now, only one high-resolution study of cubane has been performed on a few bands [2]. We report here a new wide-range high-resolution study of the infrared spectrum of cubane. The sample was synthesized in Bari upon decarboxylation of 1,4-cubanedicarboxylic acid thanks to the improved synthesis of literature [3]; its {}1H and 13C NMR, FTIR, and mass spectrometry agreed with reported data [4]. Several spectra have been recorded at the AILES beamline of the SOLEIL French synchrotron facility. They cover the 800 to 3100 cm-1 region. Besides the three infrared-active fundamentals (ν10, ν11 and ν12), we could record many combination bands, all of them displaying a well-resolved octahedral rotational structure. We present here a preliminary analysis of some of the recorded bands, performed thanks the SPVIEW and XTDS software, based on the tensrorial formalism developed in the Dijon group [5]. [1] O. Pirali, V. Boudon, J. Oomens, M. Vervloet, J. Chem. Phys., 136, 024310 (2012). [2] A. S. Pine, A. G. Maki, A. G. Robiette, B. J. Krohn, J. K. G. Watson, Th. Urbanek, J. Am. Chem. Soc., 106, 891-897 (1984). [3] P. E. Eaton, N. Nordari, J. Tsanaktsidis, P. S. Upadhyaya, Synthesis, 1, 501, (1995). [4] E

  3. Contributions of natural emissions to ozone and PM2.5 as simulated by the Community Multiscale Air Quality (CMAQ) model.

    PubMed

    Mueller, Stephen F; Mallard, Jonathan W

    2011-06-01

    The relative roles of natural and anthropogenic sources in determining ozone and fine particle concentrations over the continental United States (U.S.) are investigated using an expanded emissions inventory of natural sources and an updated version of the Community Multiscale Air Quality (CMAQ) model. Various 12-month CMAQ simulations for the year 2002 using different sets of input emissions data are combined to delineate the contributions of background pollutants (i.e., model boundary conditions), natural emissions, anthropogenic emissions, as well as the specific impacts of lightning and wildfires. Results are compared with observations and previous air quality model simulations. Wildfires and lightning are both identified as contributing significantly to ozone levels with lightning NO(x) adding as much as 25-30 ppbV (or up to about 50%) to surface 8-h average natural O(3) mixing ratios in the southeastern U.S. Simulated wildfire emissions added more than 50 ppbV (in some cases >90%) to 8-h natural O(3) at several locations in the west. Modeling also indicates that natural emissions (including biogenic, oceanic, geogenic and fires) contributed ≤ 40% to the annual average of total simulated fine particle mass over the eastern two-thirds of the U.S. and >40% across most of the western U.S. Biogenic emissions are the dominant source of particulate mass over the entire U.S. and wildfire emissions are secondary. Averaged over the entire modeling domain, background and natural ozone are dominant with anthropogenically derived ozone contributing up to a third of the total only during summer. Background contributions to fine particle levels are relatively insignificant in comparison. Model results are also contrasted with the U.S. Environmental Protection Agency (EPA) default values for natural light scattering particle concentrations to be used for regional haze regulatory decision-making. Regional differences in EPA guidance are not supported by the modeling and EPA

  4. Overview of ozone bleaching

    SciTech Connect

    Sonnenberg, L.B.

    1995-12-31

    The potential impact of the pulp and paper industry on the environment may be reduced by replacing chlorine-based bleaching reagents with ozone. The reactivity of ozone coupled with the heterogeneity of pulp allows many types of reactions to occur during pulp bleaching. Ozone cleaves the aromatic rings and side chain double bonds in lignin in Criegee-type mechanisms. Activated carbon-hydrogen bonds are fragmented in lignin side chains, as well as Cl carbons of {beta}-glycosides, by way of a 1,3 dipolar insertion forming a hydrotrioxide intermediate. Ozone also attacks carbohydrates at acetal oxygens, depolymerizing at the glycosidic bond. Unsaturated sites are ozonated before aliphatic sites resulting in a predominance of lignin reactions over carbohydrate reactions until lignin is substantially removed from the pulp. Important factors in the successful application of ozone bleaching include minimizing ozone decomposition and other secondary reactions, reducing exposure of cellulose to high concentrations of ozone and radicals, and promoting uniform exposure of ozone to lignin. The quantity of chlorinated organic compounds in effluents can be drastically reduced by replacing chlorine-based bleaching reagents with ozone; less organochlorine is formed and there can be greater recycle of bleach plant wastes back to the recovery cycle. Recycling of bleach plant waste also reduces total organic loading in the effluent. The toxicity of ozone filtrates is variable compared to conventional filtrates and depends on several parameters including bleaching conditions, biological treatment, and target organisms.

  5. Ozone and the stratosphere

    NASA Technical Reports Server (NTRS)

    Shimazaki, Tatsuo

    1987-01-01

    It is shown that the stratospheric ozone is effective in absorbing almost all radiation below 300 nm at heights below 300 km. The distribution of global ozone in the troposphere and the lower stratosphere, and the latitudinal variations of the total ozone column over four seasons are considered. The theory of the ozone layer production is discussed together with catalytic reactions for ozone loss and the mechanisms of ozone transport. Special attention is given to the anthropogenic perturbations, such as SST exhaust gases and freon gas from aerosol cans and refrigerators, that may cause an extensive destruction of the stratospheric ozone layer and thus have a profound impact on the world climate and on life.

  6. Spring polar ozone behavior

    NASA Technical Reports Server (NTRS)

    Aikin, Arthur C.

    1992-01-01

    Understanding of the springtime behavior of polar stratospheric ozone as of mid 1990 is summarized. Heterogeneous reactions on polar stratospheric clouds as hypothesis for ozone loss are considered and a simplified description of the behavior of Antarctic ozone in winter and spring is given. Evidence that the situation is more complicated than described by the theory is produced. Many unresolved scientific issues remain and some of the most important problems are identified. Ozone changes each spring since 1979 have clearly established for the first time that man made chlorine compounds influence stratospheric ozone. Long before important advances in satellite and in situ investigations, it was Dobson's decision to place a total ozone measuring spectrometer at Halley Bay in Antarctica during the International Geophysical Year and subsequent continuous monitoring which led to the discovery that ozone was being destroyed each spring by chlorine processed by polar stratospheric clouds.

  7. Surface ozone at the Devils Postpile National Monument receptor site during low and high wildland fire years

    NASA Astrophysics Data System (ADS)

    Bytnerowicz, Andrzej; Burley, Joel D.; Cisneros, Ricardo; Preisler, Haiganoush K.; Schilling, Susan; Schweizer, Donald; Ray, John; Dulen, Deanna; Beck, Christopher; Auble, Bianca

    2013-02-01

    Surface ozone (O3) was measured at the Devils Postpile National Monument (DEPO), eastern Sierra Nevada Mountains, California, during the 2007 (low-fire) and 2008 (high-fire) summer seasons. While mean and median values of O3 concentrations for the 2007 and 2008 summer seasons were similar, maximum O3 concentrations in June and August 2008 were higher than in any month of the 2007 summer season. This increase of maximum concentrations in the high-fire year is attributed to emissions of O3 precursors from wildland fires upwind of DEPO in addition to transport of polluted air from the California Central Valley (CCV) and the San Francisco Bay Area (SFBA). Analysis of backward trajectories for high O3 episodes in June 2007 and 2008 showed the lowest O3 pollution at DEPO when air masses originated over the Pacific Ocean (PO) and passed from West to East over PO and CCV at high altitudes. The highest O3 levels occurred when air masses originated in the vicinity of SFBA, swept through CCV in the NW-SE direction before reaching DEPO at low altitudes. Diurnal O3 concentrations were characterized by a sharp increase early morning and maximum values in late afternoon, followed by gradual evening decreases with very low pre-dawn minima, a phenomenon explained by local generation of O3 combined with the long range transport of polluted air masses from CCV, boundary layer destruction and surface deposition. Once in 2007, and 3 times in 2008, the 8-h average concentration exceeded 75 ppb, counting towards exceedance of the present primary Federal O3 standard (4th highest 8 h concentration <75 ppb over 3 years). The California 8-h average standard (<70 ppb) was exceeded 5 times in 2007 and 6 times in 2008, and these instances counted towards exceedance of the newly proposed primary Federal primary standard (4th highest 8-h concentration <70 ppb over 3 years). In addition, in 2008, the California 1-h average standard (<90 ppb) was exceeded 3 times. The proposed Federal secondary O3

  8. Neutron resonance averaging

    SciTech Connect

    Chrien, R.E.

    1986-10-01

    The principles of resonance averaging as applied to neutron capture reactions are described. Several illustrations of resonance averaging to problems of nuclear structure and the distribution of radiative strength in nuclei are provided. 30 refs., 12 figs.

  9. Regional-scale transport of air pollutants: impacts of southern California emissions on Phoenix ground-level ozone concentrations

    NASA Astrophysics Data System (ADS)

    Li, J.; Georgescu, M.; Hyde, P.; Mahalov, A.; Moustaoui, M.

    2015-03-01

    In this study, WRF-Chem is utilized at high-resolution (1.333 km grid spacing for the innermost domain) to investigate impacts of southern California anthropogenic emissions (SoCal) on Phoenix ground-level ozone concentrations ([O3]) for a pair of recent exceedance episodes. First, WRF-Chem Control simulations are conducted to evaluate model performance. Compared with surface observations of hourly ozone, CO, NOx, and wind fields, the Control simulations reproduce observed variability well. Simulated [O3] are within acceptance ranges recommended by the Environmental Protection Agency (EPA) that characterize skillful experiments. Next, the relative contribution of SoCal and Arizona local anthropogenic emissions (AZ) to ozone exceedance within the Phoenix metropolitan area is investigated via a trio of sensitivity simulations: (1) SoCal emissions are excluded, with all other emissions as in Control; (2) AZ emissions are excluded with all other emissions as in Control; and (3) SoCal and AZ emissions are excluded (i.e., all anthropogenic emissions are eliminated) to account only for biogenic emissions [BEO]. Results for the selected events indicate the impacts of AZ emissions are dominant on daily maximum 8 h average (DMA8) [O3] in Phoenix. SoCal contributions to DMA8 [O3] for the Phoenix metropolitan area range from a few ppbv to over 30 ppbv (10-30% relative to Control experiments). [O3] from SoCal and AZ emissions exhibit the expected diurnal characteristics that are determined by physical and photochemical processes, while BEO contributions to DMA8 [O3] in Phoenix also play a key role. Finally, ozone transport processes and pathways within the lower troposphere are investigated. During daytime, pollutants (mainly ozone) near the southern California coasts are pumped into the planetary boundary-layer over the southern California desert through the mountain chimney and pass channel effects, aiding eastward transport along the desert air basins in southern California

  10. Regional-scale transport of air pollutants: impacts of Southern California emissions on Phoenix ground-level ozone concentrations

    NASA Astrophysics Data System (ADS)

    Li, J.; Georgescu, M.; Hyde, P.; Mahalov, A.; Moustaoui, M.

    2015-08-01

    In this study, WRF-Chem is utilized at high resolution (1.333 km grid spacing for the innermost domain) to investigate impacts of southern California anthropogenic emissions (SoCal) on Phoenix ground-level ozone concentrations ([O3]) for a pair of recent exceedance episodes. First, WRF-Chem control simulations, based on the US Environmental Protection Agency (EPA) 2005 National Emissions Inventories (NEI05), are conducted to evaluate model performance. Compared with surface observations of hourly ozone, CO, NOX, and wind fields, the control simulations reproduce observed variability well. Simulated [O3] are comparable with the previous studies in this region. Next, the relative contribution of SoCal and Arizona local anthropogenic emissions (AZ) to ozone exceedances within the Phoenix metropolitan area is investigated via a trio of sensitivity simulations: (1) SoCal emissions are excluded, with all other emissions as in Control; (2) AZ emissions are excluded with all other emissions as in Control; and (3) SoCal and AZ emissions are excluded (i.e., all anthropogenic emissions are eliminated) to account only for Biogenic emissions and lateral boundary inflow (BILB). Based on the USEPA NEI05, results for the selected events indicate the impacts of AZ emissions are dominant on daily maximum 8 h average (DMA8) [O3] in Phoenix. SoCal contributions to DMA8 [O3] for the Phoenix metropolitan area range from a few ppbv to over 30 ppbv (10-30 % relative to Control experiments). [O3] from SoCal and AZ emissions exhibit the expected diurnal characteristics that are determined by physical and photochemical processes, while BILB contributions to DMA8 [O3] in Phoenix also play a key role. Finally, ozone transport processes and pathways within the lower troposphere are investigated. During daytime, pollutants (mainly ozone) near the Southern California coasts are pumped into the planetary boundary-layer over the Southern California desert through the mountain chimney and pass

  11. A global tropospheric ozone climatology from trajectory-mapped ozone soundings

    NASA Astrophysics Data System (ADS)

    Liu, G.; Liu, J. J.; Tarasick, D. W.; Fioletov, V. E.; Jin, J. J.; Moeni, O.; Liu, X.; Sioris, C. E.

    2013-05-01

    A global three-dimensional (i.e. latitude, longitude, altitude) climatology of tropospheric ozone is derived from the ozone sounding record by trajectory mapping. Approximately 52 000 ozonesonde profiles from more than 100 stations worldwide since 1962 are used. The small number of stations causes the set of ozone soundings to be sparse in geographical spacing. Here, forward and backward trajectory calculations are performed for each sounding to map ozone measurements to a number of other locations, and so to fill in the spatial domain. This is possible because the lifetime of ozone in the troposphere is of the order of weeks. This physically-based interpolation method offers obvious advantages over typical statistical interpolation methods. The trajectory-mapped ozone values show reasonable agreement, where they overlap, to the actual soundings, and the patterns produced separately by forward and backward trajectory calculations are similar. Major regional features of the tropospheric ozone distribution are clearly evident in the global maps. An interpolation algorithm based on spherical functions is further used for smoothing and to fill in remaining data gaps. The resulting three-dimensional global tropospheric ozone climatology facilitates visualization and comparison of different years, decades, and seasons, and offers some intriguing insights into the global variation of tropospheric ozone. It will be useful for climate and air quality model initialization and validation, and as an a priori climatology for satellite data retrievals. Further division of the climatology into decadal averages provides a global view of tropospheric ozone trends, which appear to be surprisingly modest over the last four decades.

  12. Spatial patterns of tropospheric ozone in the Mount Rainier region of the Cascade Mountains, USA

    USGS Publications Warehouse

    Brace, S.; Peterson, D.L.

    1998-01-01

    Few data exist on tropospheric ozone concentrations in rural and wildland areas of western Washington, U.S.A. We measured tropospheric ozone in Mount Rainier National Park and the Puget Sound region of Washington using electronic analyzers and passive samplers during the summers of 1994 and 1995. Electronic analyzers recorded hourly ozone concentrations from five locations between Seattle and Mount Rainier. Ozone concentrations generally increased with distance from Seattle, with maximum hourly concentrations recorded at Enumclaw (319 m elevation, 50 km SE of Seattle). Paradise (1650 m elevation, 100 km SE of Seattle) had the highest monthly mean concentration of all sites measured with analyzers. Diurnal patterns on high-ozone days indicate that concentrations at Paradise remain near 60 ppbv throughout the day, whereas ozone concentrations closer to Seattle had higher peaks during the afternoon but dropped to near zero at night. Passive ozone samplers were used to measure weekly average ozone exposures in four river drainages within Mount Rainier National Park, across an elevation gradient (420 a??2100 m). In most drainages, ozone levels increased with elevation, with highest average weekly ozone exposure (47 ppbv) recorded at 2100 m. Ozone concentrations are significantly higher in the western portion of the park, indicating that ozone exposure varies considerably over short distances. These data provide a reference point for air quality in western Washington and indicate that intensive sampling is necessary to quantify spatial patterns of tropospheric ozone in mountainous regions.

  13. Microbubble enhanced ozonation process for advanced treatment of wastewater produced in acrylic fiber manufacturing industry.

    PubMed

    Zheng, Tianlong; Wang, Qunhui; Zhang, Tao; Shi, Zhining; Tian, Yanli; Shi, Shanshan; Smale, Nicholas; Wang, Juan

    2015-04-28

    This work investigated microbubble-ozonation for the treatment of a refractory wet-spun acrylic fiber wastewater in comparison to macrobubble-ozonation. CODcr, NH3-N, and UV254 of the wastewater were removed by 42%, 21%, and 42%, respectively in the microbubble-ozonation, being 25%, 9%, and 35% higher than the removal rates achieved by macrobubble-ozonation at the same ozone dose. The microbubbles (with average diameter of 45μm) had a high concentration of 3.9×10(5) counts/mL at a gas flow rate of 0.5L/min. The gas holdup, total ozone mass-transfer coefficient, and average ozone utilization efficiency in the microbubble-ozonation were 6.6, 2.2, and 1.5 times higher than those of the macrobubble-ozonation. Greater generation of hydroxyl radicals and a higher zeta potential of the bubbles were also observed in the microbubble ozonation process. The biodegradability of the wastewater was also significantly improved by microbubble-ozonation, which was ascribed to the enhanced degradation of alkanes, aromatic compounds, and the many other bio-refractory organic compounds in the wastewater. Microbubble-ozonation can thus be a more effective treatment process than traditional macrobubble-ozonation for refractory wastewater produced by the acrylic fiber manufacturing industry. PMID:25681716

  14. The F8H Glycosyltransferase is a Functional Paralog of FRA8 Involved in Glucuronoxylan Biosynthesis in Arabidopsis

    EPA Science Inventory

    The FRAGILE FIBER8 gene was previously shown to be required for the biosynthesis of the reducing end tetrasaccharide sequence of glucuronoxylan (GX) in Arabidopsis thaliana. Here, we demonstrate that F8H, a close homolog of FRA8, is a functional ortholog of FRA8 involved in GX bi...

  15. Ozone trends: A review

    NASA Astrophysics Data System (ADS)

    Staehelin, J.; Harris, N. R. P.; Appenzeller, C.; Eberhard, J.

    2001-05-01

    Ozone plays a very important role in our atmosphere because it protects any living organisms at the Earth's surface against the harmful solar UVB and UVC radiation. In the stratosphere, ozone plays a critical role in the energy budget because it absorbs both solar UV and terrestrial IR radiation. Further, ozone in the tropopause acts as a strong greenhouse gas, and increasing ozone trends at these altitudes contribute to climate change. This review contains a short description of the various techniques that provided atmospheric ozone measurements valuable for long-term trend analysis. The anthropogenic emissions of substances that deplete ozone (chlorine- and bromine-containing volatile gases) have increased from the 1950s until the second half of the 1980s. The most severe consequence of the anthropogenic release of ozone-depleting substances is the "Antarctic ozone hole." Long-term observations indicate that stratospheric ozone depletion in the southern winter-spring season over Antarctica started in the late 1970s, leading to a strong decrease in October total ozone means. Present values are only approximately half of those observed prior to 1970. In the Arctic, large ozone depletion was observed in winter and spring in some recent years. Satellite and ground-based measurements show no significant trends in the tropics but significant long-term decreasing trends in the northern and southern midlatitudes (of the order of 2-4% per decade in the period from 1970 to 1996 and an acceleration in trends in the 1980s). Ozone at northern midlatitudes decreased by -7.4±2% per decade at 40 km above mean sea level, while ozone loss was small at 30 km. Large trends were found in the lower stratosphere, -5.1±1.8% at 20 km and -7.3±4.6% at 15 km, where the bulk of the ozone resides. The possibility of a reduction in the observed trends has been discussed recently, but it is very hard to distinguish this from the natural variability. As a consequence of the Montreal Protocol

  16. Interannual Variability of Ozone and Ultraviolet Exposure

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Piacentini, R. D.; Ziemke, J.; Celarier, E.; Larko. D.

    1999-01-01

    Annual zonal averages of ozone amounts from Nimbus-7/TOMS (Total Ozone Mapping Spectrometer) (1979 to 1992) are used to estimate the interannual variability of ozone and UVB (290 - 315 nm) irradiance between plus or minus 60 deg. latitude. Clear-sky interannual ozone and UVB changes are mainly caused by the Quasi Biennial Oscillation (QBO) of stratospheric winds, and can amount to plus or minus 15% at 300 nm and plus or minus 5% at 310 nm (or erythemal irradiance) at the equator and at middle latitudes. Near the equator, the interannual variability of ozone amounts and UV irradiance caused by the combination of the 2.3 year QBO and annual cycles implies that there is about a 5-year periodicity in UVB variability. At higher latitudes, the appearance of the interannual UVB maximum is predicted by the QBO, but without the regular periodicity. The 5-year periodic QBO effects on UVB irradiance are larger than the currently evaluated long-term changes caused by the decrease in ozone amounts.

  17. A New SBUV Ozone Profile Time Series

    NASA Technical Reports Server (NTRS)

    McPeters, Richard

    2011-01-01

    Under NASA's MEaSUREs program for creating long term multi-instrument data sets, our group at Goddard has re-processed ozone profile data from a series of SBUV instruments. We have processed data from the Nimbus 7 SBUV instrument (1979-1990) and data from SBUV/2 instruments on NOAA-9 (1985-1998), NOAA-11 (1989-1995), NOAA-16 (2001-2010), NOAA-17 (2002-2010), and NOAA-18 (2005-2010). This reprocessing uses the version 8 ozone profile algorithm but now uses the Brion, Daumont, and Malicet (BMD) ozone cross sections instead of the Bass and Paur cross sections. The new cross sections have much better resolution, and extended wavelength range, and a more consistent temperature dependence. The re-processing also uses an improved cloud height climatology based on the Raman cloud retrievals of OMI. Finally, the instrument-to-instrument calibration is set using matched scenes so that ozone diurnal variation in the upper stratosphere does not alias into the ozone trands. Where there is no instrument overlap, SAGE and MLS are used to estimate calibration offsets. Preliminary analysis shows a more coherent time series as a function of altitude. The net effect on profile total column ozone is on average an absolute reduction of about one percent. Comparisons with ground-based systems are significantly better at high latitudes.

  18. Erythrocyte survival in sheep exposed to ozone

    SciTech Connect

    Moore, G.S.; Calabrese, E.J.; Labato, F.J.

    1981-07-01

    Erythrocyte survival studies in the Dorset ewe using chromium 51 were performed. The purpose of the study was to determine if ozone exposure produces decreased cell survival which may be the result of premature erythrocyte aging. This strain of sheep has an erythrocyte glucose-6-phosphate dehydrogenase (G6PD) activity that is very low, being comparable to human A-variants with G6PD deficiency. Ozone exposure may produce hemolytic effects in G6PD deficients more readily than in erythrocytes with normal activity. A decrease in hematocrit was observed in the ozone exposed groups. With respect to red cell destruction, ozone does not appear to act immediately, but rather there appears to be a delayed effect. At 0.25 ppM ozone, the group reached the 50% remaining level an average of 1 day sooner than the control group. There was no significant difference between control and exposed groups at the 0.50 ppM and 0.70 ppM levels. Also, the results demonstrate a net decrease in hematocrit which is greater for 0.25 ppM ozone than any other exposure level. (RJC)

  19. Simultaneous measurements of ozone outside and inside cabins of two B-747 airliners and a Gates Learjet business jet

    NASA Technical Reports Server (NTRS)

    Perkins, P. J.; Briel, D.

    1978-01-01

    The average amount of ozone measured in the cabins of two B-747 airliners varied from 40 percent to 80 percent of the atmospheric concentrations without special ozone destruction systems. A charcoal filter in the cabin air inlet system of one B-747 reduced the ozone to about 5 percent of the atmospheric concentration. A Learjet 23 was also instrumented with monitors to measure simultaneously the atmospheric and ozone concentrations. Results indicate that a significant portion of the atmospheric ozone is not destroyed in the pressurization system and remains in the aircraft cabin of the Learjet. For the two cabin configurations tested, the ozone retentions were 63 and 41 percent of the atmospheric ozone concentrations. Ozone concentrations measured in the cabin near the conditioned-air outlets were reduced only slightly from atmospheric ozone concentrations. It is concluded that a constant difference between ozone concentrations inside and outside the cabin does not exist.

  20. Ozone-Initiated Chemistry in an Occupied Simulated AircraftCabin

    SciTech Connect

    Weschler, C.J.; Wisthaler, A.; Cowlind, S.; Tamas, G.; Strom-Tejsena, P.; Hodgson, A.T.; Destaillats, H.; Herrington, J.; Zhang,J.; Nazaroff, W.W.

    2007-07-01

    We have used multiple analytical methods to characterize the gas-phase products formed when ozone was added to cabin air during simulated 4-hour flights that were conducted in a reconstructed section of a B-767 aircraft containing human occupants. Two separate groups of 16 females were each exposed to four conditions: low air exchange (4.4 h-1), <2 ppb ozone; low air exchange, 61-64 ppb ozone; high air exchange (8.8 h-1), <2 ppb ozone; and high air exchange, 73-77 ppb ozone. The addition of ozone to the cabin air increased the levels of identified byproducts from {approx}70 to 130 ppb at the lower air exchange rate and from {approx}30 to 70 ppb at the higher air exchange rate. Most of the increase was attributable to acetone, nonanal, decanal, 4-oxopentanal (4-OPA), 6-methyl-5-hepten-2-one (6-MHO), formic acid, and acetic acid, with 0.25-0.30 mol of quantified product volatilized per mol of ozone consumed. Several of these compounds reached levels above their reported odor thresholds. Most byproducts were derived from surface reactions with occupants and their clothing, consistent with the inference that occupants were responsible for the removal of >55% of the ozone in the cabin. The observations made in this study have implications for other indoor settings. Whenever human beings and ozone are simultaneously present, one anticipates production of acetone, nonanal, decanal, 6-MHO, geranyl acetone, and 4-OPA.

  1. Comparison of SBUV and SAGE II ozone profiles: Implications for ozone trends

    NASA Technical Reports Server (NTRS)

    Mcpeters, R. D.; Miles, T.; Flynn, L. E.; Wellemeyer, C. G.; Zawodny, J. M.

    1994-01-01

    Solar backscattered ultraviolet (SBUV) ozone profiles have been compared with Stratospheric Aerosol and Gas Experiment (SAGE) II profiles over the period October 1984 through June 1990, when data are available from both instruments. SBUV measurements were selected to closely match the SAGE II latitude/longitude measurement pattern. There are significant differences between the SAGE II sunrise and the sunset zonal mean ozone profiles in the equatorial zone, particularly in the upper stratosphere, that may be connected with extreme SAGE II solar azimuth angles for tropical sunrise measurements. Calculation of the average sunset bias between SBUV and SAGE II ozone profiles shows that allowing for diurnal variation in Umkehr layer 10, SBUV and SAGE II agree to within +/- 5% for the entire stratosphere in the northern midlatitude zone. The worst agreement is seen at southern midlatitudes near the ozone peak (disagreements of +/- 10%), apparently the result of the SBUV ozone profile peaking at a lower altitude than SAGE. The integrated ozone columns (cumulative above 15 km) agree very well, to within +/- 2.3% in all zones for both sunset and sunrise measurements. A comparison of the time dependence of SBUV and SAGE II shows that there was less than +/- 5% relative drift over the 5.5 years for all altitudes except below 25 km, where the SBUV vertical resolution is poor. The best agreement with SAGE is seen in the integrated column ozone (cumulative above 15 km), where SAGE II has a 1% negative trend relative to SBUV over the comparison period. There is a persistent disagreement of the two instruments in Umkehr layers 9 and 10 of +/- 4% over the 5.5-year comparison period. In the equatorial zone this disagreement may be caused in part by a large positive trend (0.8 K per year) in the National Meteorologica Center temperatures used to convert the SAGE II measurement of ozone density versus altitude to a pressure scale for comparison with SBUV. In the middle stratosphere (30

  2. Rebound of Antarctic ozone

    NASA Astrophysics Data System (ADS)

    Salby, Murry; Titova, Evgenia; Deschamps, Lilia

    2011-05-01

    Restrictions on CFCs have led to a gradual decline of Equivalent Effective Stratospheric Chlorine (EESC). A rebound of Antarctic ozone, however, has remained elusive, masked by large interannual changes that dominate its current evolution. A positive response of ozone is not expected to emerge for at least 1-2 decades, possibly not for half a century. We show that interannual changes of the Antarctic ozone hole are accounted for almost perfectly by changes in dynamical forcing of the stratosphere. The close relationship enables dynamically-induced changes of ozone to be removed, unmasking the climate signal associated with CFCs. The component independent of dynamically-induced changes exhibits a clear upward trend over the last decade - the first signature of a rebound in Antarctic ozone. It enables ozone to be tracked relative to CFCs and other changes of climate.

  3. Ozone therapy in periodontics

    PubMed Central

    Gupta, G; Mansi, B

    2012-01-01

    Gingival and Periodontal diseases represent a major concern both in dentistry and medicine. The majority of the contributing factors and causes in the etiology of these diseases are reduced or treated with ozone in all its application forms (gas, water, oil). The beneficial biological effects of ozone, its anti-microbial activity, oxidation of bio-molecules precursors and microbial toxins implicated in periodontal diseases and its healing and tissue regeneration properties, make the use of ozone well indicated in all stages of gingival and periodontal diseases. The primary objective of this article is to provide a general review about the clinical applications of ozone in periodontics. The secondary objective is to summarize the available in vitro and in vivo studies in Periodontics in which ozone has been used. This objective would be of importance to future researchers in terms of what has been tried and what the potentials are for the clinical application of ozone in Periodontics. PMID:22574088

  4. Infection risk and stability of a continuous 8-h 250 mL rFVIII infusion.

    PubMed

    Lambing, A; Kuriakose, P; Mueller, L M

    2014-03-01

    This study seeks to identify the delivery method of continuous infusion using a 250 cc IV bag via pump, change every 8 h. Additionally, the study will examine the infection risk with the use of 8 h infusions. Ten hemophilia A patients were identified for the study. Each patient received a bolus factorVIII (FVIII) infusion with a pre FVIII level and 1 h post FVIII level to determine recovery levels for optimal dosing. On the day of 8-h continuous infusion, the pt received a bolus VIII (Kogenate FS (™)) for correction to 100% followed by individually calculated continuous infusion (Kogenate FS (™)) FVIII. FVIII levels were drawn from the IV bag and peripherally from the patient in the opposite arm at time points: pre infusion, 1, 2, 3, 4, 5, 6 and 8 h. Additionally, blood cultures were drawn from the IV bag and from the IV tubing at time points pre infusion, 4 and 8 h. Fourteen subjects agreed to participate in the study; 4 failed to follow up, hence 10 subjects were included in the analysis of data; 7 severe, 2 moderate, and 1 mild hemophilia A. Age range was 26-62 years. Ethnic breakdown included 5 African American, 4 Caucasian, 1 Hispanic. With all infusions, the range of FVIII was 65-135% (blood) and 62-200% (bag). After the start of infusion, there were no significant differences noted between the hourly FVIII levels in the subjects and the IV values (P-value range 0.36-0.9). Additionally, given three time points with six cultures per patient, totaling 60 points of cultures drawn for the study, all cultures from the IV bag and patient were negative. The effective delivery method and safety of an 8-h continuous infusion of FVIII (Kogenate FS (™)) has been confirmed. This method can be helpful given that many hospitals may not carry the required mini-pumps, allowing a standard safe delivery of FVIII (Kogenate FS (™)) continuous infusion by available means. PMID:24251950

  5. Ozone flow visualization techniques

    NASA Technical Reports Server (NTRS)

    Dickerson, R. R.; Stedman, D. H.

    1981-01-01

    Flow visualization techniques using ozone for tracing gas flows are proposed whereby ozone is detected through its strong absorption of ultraviolet light, which is easily made visible with fluorescent materials, or through its reaction with nitric oxide to form excited nitrogen dioxide, which in relaxing emits detectable light. It is shown that response speeds in the kHz range are possible with an ultraviolet detection system for initial ozone concentrations of about 1%.

  6. The Antarctic ozone hole

    NASA Technical Reports Server (NTRS)

    Stolarski, Richard S.

    1988-01-01

    Processes that may be responsible for the thinning in the ozone layer above the South Pole are described. The chlorine catalytic cycle which destroys ozone is described, as are the major types of reactions that are believed to interfere with this cycle by forming chlorine reservoirs. The suspected contributions of polar stratospheric clouds to these processes are examined. Finally, the possibility that the ozone hole may be due more to a shift in atmospheric dynamics than to chemical destruction is addressed.

  7. The impact of decreases in air temperature and increases in ozone on markers of endothelial function in individuals having type-2 diabetes.

    PubMed

    Lanzinger, Stefanie; Breitner, Susanne; Neas, Lucas; Cascio, Wayne; Diaz-Sanchez, David; Hinderliter, Alan; Peters, Annette; Devlin, Robert B; Schneider, Alexandra

    2014-10-01

    Several studies have reported an association between air pollution and endothelial dysfunction, especially in individuals having diabetes. However, very few studies have examined the impact of air temperature on endothelial function. The objective of this analysis was to investigate short-term effects of temperature and ozone on endothelial function in individuals having diabetes. Moreover, we investigated interactive effects between air temperature and air pollution on markers of endothelial function. Between November 2004 and December 2005 flow-mediated dilatation (FMD), nitroglycerin-mediated dilatation (NTGMD) and several blood markers representing endothelial function were measured using brachial artery ultrasound on four consecutive days in 22 individuals with type-2 diabetes mellitus in Chapel Hill, North Carolina (USA). Daily measurements of meteorological parameters, ozone and particulate matter with an aerodynamic diameter ≤2.5 µm (PM2.5) were obtained from fixed monitoring sites. We used additive mixed-models adjusting for time trend, day of the week, relative humidity and barometric pressure to assess temperature and ozone associations with endothelial function. A 1 °C decrease in the 24-h temperature average was associated with a decrease in mean FMD on the same day (-2.2% (95%-confidence interval:[-4.7;0.3%])) and with a delay of one and four days. A temperature decrement also led to an immediate (-1.7%[-3.3;-0.04]) decrease in NTGMD. Moreover, we observed an immediate (-14.6%[-26.3;-2.9%]) and a one day delayed (-13.5%[-27.0; 0.04%]) decrease in FMD in association with a 0.01 ppm increase in the maximum 8-h moving average of ozone. Temperature effects on FMD strengthened when PM2.5 and ozone concentrations were high. The associations were similar during winter and summer. We detected an association between temperature decreases and ozone increases on endothelial dysfunction in individuals having diabetes. We conclude that endothelial dysfunction

  8. An automated ozone photometer

    NASA Technical Reports Server (NTRS)

    Lavelle, Joseph R.

    1988-01-01

    A photometer capable of automatically measuring ozone concentration data to very high resolution during scientific research flights in the earth's atmosphere was developed at the NASA Ames Research Center. This instrument was recently deployed to study the ozone hole over Antarctica. Ozone is detected by absorbing 253.7-nm radiation from an ultraviolet lamp which shines through the sample of air and impinges on a vacuum phototube. A lower output from the phototube indicates more ozone present in the air sample. The photometer employs a CMOS 280 control, data collection, and storage.

  9. Total ozone trend significance from space time variability of daily Dobson data

    NASA Technical Reports Server (NTRS)

    Wilcox, R. W.

    1981-01-01

    Estimates of standard errors of total ozone time and area means, as derived from ozone's natural temporal and spatial variability and autocorrelation in middle latitudes determined from daily Dobson data are presented. Assessing the significance of apparent total ozone trends is equivalent to assessing the standard error of the means. Standard errors of time averages depend on the temporal variability and correlation of the averaged parameter. Trend detectability is discussed, both for the present network and for satellite measurements.

  10. Impacts of Global Climate Change and Emissions on Regional Ozone and Fine Particulate Matter Concentrations over United States

    SciTech Connect

    Tagaris, Efthimios; Manomaiphiboon, Kasemsan; Liao, Kuo-Jen; Leung, Lai R.; Woo, Jung-Hun; He, Shan; Amar, Praveen; Russell, Armistead G.

    2007-07-31

    Simulated future summers (i.e., 2049-2051) and annual (i.e., 2050) average regional O 3 and PM2.5 concentrations over North America are compared with historic (i.e., 2000-2002 summers and all of 2001) levels to investigate the potential impacts of global climate change on regional air quality. Meteorological inputs to the CMAQ chemical transport model are developed by downscaling the GISS Global Climate Model simulations using an MM5-based regional climate model. Future-year emissions for North America are developed by growing the US EPA CAIR inventory, Mexican and Canadian emissions and by using the IMAGE model with the IPCC A1B emissions scenario that is also used in projecting future climate. Reductions of more than 50% in NOX and SO2 emissions are forecast. The impacts of global climate change alone on regional air quality are small compared to impacts from emission control-related reductions in the US and Canada. The combined effect of climate change and emission reductions lead to a 20% decrease (regionally varying from -11% to -28% regionally) in the mean summer maximum daily 8-hr ozone levels (M8hO3) over the US, -8% over Canada and -10% over Northern Mexico. The mean annual PM2.5 concentrations are estimated to be 23% lower (varies from -9% to -32%) over the US, -7% and -15% over Western and Eastern Canada, respectively and -25% over Northern Mexico. Major reductions are expected in sulfate, nitrate and ammonium fractions of annually-averaged PM2.5 for all sub-regions. The limited reduction in organic carbon over the US and Northern Mexico and the higher concentrations over Canada suggests that organic carbon will be the dominant component of PM2.5 mass over most of the continent in the future. Regionally, the Eastern US benefits more than the rest of the regions from reductions in both M8hO3 and PM2.5, due to both spatial variations in the meteorological and emissions changes. Reduction in the higher M8hO3 concentrations is also estimated for all sub

  11. Detection and Attribution of the Recovery of Polar Ozone

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.; Nash, E. R.; Douglass, A. R.; Nielsen, J. E.; Pawson, S.; Stolarski, R. S.

    2008-01-01

    The Antarctic ozone hole develops each year and culminates by early spring (late September - early October). The severity of the hole has been assessed from satellites using the minimum total ozone value from the October monthly mean (depth of the hole), calculating the average area coverage during this September-October period, and by estimating ozone mass deficit. Profile information shows that ozone is completely destroyed in the 14-2 1 km layer by early October. Ozone is mainly destroyed by halogen (chlorine and bromine) catalytic cycles, and these losses are modulated by temperature variations. Because atmospheric halogen levels are responding to international agreements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. Both models and projections of ozone depleting substances (ODSs) into the 21St century reveal that polar ozone levels should recover in the 2060- 2070 period. In this talk, we will review current projections of polar ozone recovery. Using models and ODs projections, we explore both the past, near future (2008-2025), and far future (> 2025) levels of polar ozone. Finally, we will discuss various factors that complicate recovery such as greenhouse gas changes (e.g., cooling in the upper stratosphere) and the acceleration of the Brewer-Dobson circulation.

  12. Ozone trends in Atlanta, Georgia - Have emission controls been effective?

    NASA Technical Reports Server (NTRS)

    Lindsay, Ronald W.; Richardson, Jennifer L.; Chameldes, William L.

    1989-01-01

    Nine years of summertime ozone data from the Atlanta metropolitan area are analyzed and compared to local emissions of volatile organic carbon and nitrogen oxides. Trends from 1979 to 1987 were studied for the number of days per year ozone exceeded the NAAQS standard, the second-highest ozone level observed per year, and the first quartile summertime average ozone observed, as well as the mean difference between the ozone level observed downwind and upwind of the city. Because this last parameter is sensitive to chemical factors but relatively insensitive to the number of days each year with meteorological conditions conducive to ozone formation, its trend may be best suited for determining how effective emission controls have been in reducing O3 in the Atlanta area. In spite of the fact that sizeable reductions have been claimed for volatile organic carbon emissions over the past several years, the data give no indication that ozone levels have decreased and in fact, imply that summertime ozone production may have increased. The results imply that either emissions have not decreased as much as has been claimed or that ozone is not sensitive to anthropogenic volatile organic carbon emissions.

  13. The Impact of Increasing Carbon Dioxide on Ozone Recovery

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.; Douglass, Anne R.; Considine, David B.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    We have used the GSFC coupled two-dimensional (2D) model to study the impact of increasing carbon dioxide from 1980 to 2050 on the recovery of ozone to its pre-1980 amounts. We find that the changes in temperature and circulation arising from increasing CO2 affect ozone recovery in a manner which varies greatly with latitude, altitude, and time of year. Middle and upper stratospheric ozone recovers faster at all latitudes due to a slowing of the ozone catalytic loss cycles. In the lower stratosphere, the recovery of tropical ozone is delayed due to a decrease in production and a speed up in the overturning circulation. The recovery of high northern latitude lower stratospheric ozone is delayed in spring and summer due to an increase in springtime heterogeneous chemical loss, and is speeded up in fall and winter due to increased downwelling. The net effect on the higher northern latitude column ozone is to slow down the recovery from late March to late July, while making it faster at other times. In the high southern latitudes, the impact of CO2 cooling is negligible. Annual mean column ozone is predicted to recover faster at all latitudes, and globally averaged ozone is predicted to recover approximately ten years faster as a result of increasing CO2.

  14. Nimbus 7 solar backscatter ultraviolet (SBUV) ozone products user's guide

    NASA Technical Reports Server (NTRS)

    Fleig, Albert J.; Mcpeters, R. D.; Bhartia, P. K.; Schlesinger, Barry M.; Cebula, Richard P.; Klenk, K. F.; Taylor, Steven L.; Heath, Donald F.

    1990-01-01

    Three ozone tape products from the Solar Backscatter Ultraviolet (SBUV) experiment aboard Nimbus 7 were archived at the National Space Science Data Center. The experiment measures the fraction of incoming radiation backscattered by the Earth's atmosphere at 12 wavelengths. In-flight measurements were used to monitor changes in the instrument sensitivity. Total column ozone is derived by comparing the measurements with calculations of what would be measured for different total ozone amounts. The altitude distribution is retrieved using an optimum statistical technique for the inversion. The estimated initial error in the absolute scale for total ozone is 2 percent, with a 3 percent drift over 8 years. The profile error depends on latitude and height, smallest at 3 to 10 mbar; the drift increases with increasing altitude. Three tape products are described. The High Density SBUV (HDSBUV) tape contains the final derived products - the total ozone and the vertical ozone profile - as well as much detailed diagnostic information generated during the retrieval process. The Compressed Ozone (CPOZ) tape contains only that subset of HDSBUV information, including total ozone and ozone profiles, considered most useful for scientific studies. The Zonal Means Tape (ZMT) contains daily, weekly, monthly and quarterly averages of the derived quantities over 10 deg latitude zones.

  15. A global tropospheric ozone climatology from trajectory-mapped ozone soundings

    NASA Astrophysics Data System (ADS)

    Liu, G.; Liu, J.; Tarasick, D. W.; Fioletov, V. E.; Jin, J. J.; Moeini, O.; Liu, X.; Sioris, C. E.; Osman, M.

    2013-11-01

    A global three-dimensional (i.e. latitude, longitude, altitude) climatology of tropospheric ozone is derived from the ozone sounding record by trajectory mapping. Approximately 52 000 ozonesonde profiles from more than 100 stations worldwide since 1965 are used. The small number of stations results in a sparse geographical distribution. Here, forward and backward trajectory calculations are performed for each sounding to map ozone measurements to a number of other locations, and so to fill in the spatial domain. This is possible because the lifetime of ozone in the troposphere is of the order of weeks. This physically based interpolation method offers obvious advantages over typical statistical interpolation methods. The trajectory-mapped ozone values show reasonable agreement, where they overlap, to the actual soundings, and the patterns produced separately by forward and backward trajectory calculations are similar. Major regional features of the tropospheric ozone distribution are clearly evident in the global maps. An interpolation algorithm based on spherical functions is further used for smoothing and to fill in remaining data gaps. The resulting three-dimensional global tropospheric ozone climatology facilitates visualization and comparison of different years, decades, and seasons, and offers some intriguing insights into the global variation of tropospheric ozone. It will be useful for climate and air quality model initialization and validation, and as an a priori climatology for satellite data retrievals. Further division of the climatology into decadal and annual averages can provide a global view of tropospheric ozone changes, although uncertainties with regard to the performance of older sonde types, as well as more recent variations in operating procedures, need to be taken into account.

  16. Dynamics of the reaction of C{sub 2} with C{sub 6}H{sub 2}: An implication for the formation of interstellar C{sub 8}H

    SciTech Connect

    Sun, Yi-Lun; Huang, Wen-Jian; Chin, Chih-Hao; Lee, Shih-Huang

    2014-11-21

    The reaction C{sub 2} + C{sub 6}H{sub 2} → C{sub 8}H + H was investigated for the first time. Reactant C{sub 2} (C{sub 6}H{sub 2}) was synthesized from 1% C{sub 3}F{sub 6}/He (5% C{sub 2}H{sub 2}/He) by pulsed high-voltage discharge. We measured the translational-energy distribution, the angular distribution, and the photoionization spectrum of product C{sub 8}H in a crossed molecular-beam apparatus using synchrotron vacuum-ultraviolet ionization. This reaction released average translational energy of 8.5 kcal mol{sup −1} corresponding to a fraction of 0.37 in translation. C{sub 8}H was identified as octatetranyl based on the maximal translational-energy release 23 ± 2 kcal mol{sup −1} and the ionization threshold 8.9 ± 0.2 eV. Kinematic constraints can qualitatively account for the nearly isotropic angular distribution. The quantum-chemical calculations indicate that the exothermic reactions C{sub 2} (X {sup 1}Σ{sub g}{sup +}/a {sup 3}Π{sub u}) + HC{sub 6}H → C{sub 8}H + H can proceed without entrance and exit barriers, implying the importance in the cold interstellar medium. This work verifies that interstellar C{sub 8}H can be formed through the C{sub 2} + C{sub 6}H{sub 2} reaction.

  17. Occurrence of ozone as a phytotoxicant in Kiev, Ukraine and in the Ukrainian Carpathian mountains

    SciTech Connect

    Bytnerowicz, A.; Manning, W.; Blum, O.; Popovicheva, L.

    1995-12-31

    Ogawa passive ozone samplers were established at the Central Botanic Garden in Kiev and in five forest locations in the Ukrainian Carpathian mountains in summer, 1995. An active ozone monitor (Thermo-Electron 49) was also established at the Botanic Garden, together with plants of ozone-sensitive (Bel-W3) and ozone-tolerant (Bel-B) tobacco (Nicotiana tabacum). The highest average hourly ozone concentration monitored in Kiev was 84.4 ppb. From August to September, two-week average concentrations of ozone (Ogawa samplers) in the Carpathian forests ranged from 27.4--51.8 ppb. During a two-week exposure period, Bel-W3 tobacco plants in Kiev had foliar injury on leaf one as high as 62%, with only 13% for Bel-B. Ozone injury was found on a variety of indicator plants in Kiev and at three of the five passive sampler sites in the Carpathians.

  18. Structure and Raman spectra of single crystal La 2(SO 4) 3 · 8H 2O

    NASA Astrophysics Data System (ADS)

    Vanderpool, Richard A.; Khan, Masood A.; Frech, Roger

    1991-05-01

    The room temperature polarized Raman spectra of single-crystal La 2(SO 4) 3 · 8H 2O have been measured in the range 5-4000 cm -1. The internal and external modes,based on a factor group analysis and comparison with Na 2SO 4 and La 2(SO 4) 3 · 9H 2O, have been assigned. A single-crystal X-ray diffraction study shows that La 2(SO 40 3 · 8H 2O crystallizes in the monoclinic space group Pn ( Z = 2) with cell dimensions a = 6.881(2) Å, b = 17.376(4) Å, c = 6.923(2) Å, and β = 92.34 (2)°. The structure was refined to a final R = 0.033 for 2333 observed reflections.

  19. Results of ozone measurements in Northern Germany: A case study

    NASA Technical Reports Server (NTRS)

    Schmidt, Manfred

    1994-01-01

    At most of the German ozone recording stations which have records over a sufficiently long period, the results of the summer months of 1989 showed the highest values since the beginning of the measurements. One of the reasons for this phenomenon was the high duration of sunshine in that summer; for example, in Potsdam near Berlin in May 1989 the sunshine duration was the highest in May since the beginning of the records in 1893. For that reason we selected this summer for a case study. The basis for the study was mainly the ozone measuring stations of the network of Lower Saxony and the Federal Office of Environment (Umweltbundesamt). The results of these summer measurements point to intense sources of ozone, probably in form of gaseous precursors, in the Middle German industrial areas near Leipzig and Halle and in Northwestern Czechoslovakia, with coal-mining, chemical and petrochemical industries, coking plants and others. The maps of average ozone concentrations, number or days with high ozone maxima, ozone-windroses of the stations, etc., suggest that these areas could be a main source of precursors and of photochemical ozone production in summer smog episodes in Central Europe. Stations on the North Sea coast, at which early ozone measurements were made by our institute in 1973/74 are compared with similarly located stations of the Lower Saxon network in 1989 and the results show a reversal of the ozone-windroses. In 1973/74, the highest ozone concentrations were correlated with wind directions from the sea while in 1989 these concentrations were correlated with directions from the continent. In the recent years, photochemical ozone production on the continent is probably predominant, while in former years the higher ozone content of the maritime subpolar air masses has been explained by stratospheric-tropospheric exchange.

  20. Biomonitoring of tropospheric ozone phytotoxicity in rural Catalonia

    NASA Astrophysics Data System (ADS)

    Ribas, Angela; Peñuelas, Josep

    The ozone (O 3) phytotoxicity in rural areas of Catalonia (NE Spain) and the biomonitoring capacity of Bel-W3 tobacco ( Nicotiana tabacum) cultivars were assessed by determining the percentage of leaf area injured by ozone in plants of this cultivar exposed from spring to autumn since 1995-1999. The study was conducted simultaneously on nine field sites where ground level ozone concentrations and meteorological parameters were continuously monitored. Geographical, seasonal and annual variations of ozone damage rate and their links with meteorological conditions were studied. Ozone concentrations and leaf damage increased at the end of spring and the beginning of summer. Coastal sites generally presented higher O 3 concentrations than inland and mountain sites. These mountain sites were the most sensitive ones to ozone toxicity. The ozone concentrations correlated well with ozone injury. However, at this local scale the ozone levels did not fully account for all the observed injury (only 11%). The response of tobacco plants to ozone concentrations and therefore its biomonitoring capacity depended also on different environmental conditions, mainly those linked to stomatal behaviour such as vapour pressure deficit. The categorization of leaf damage in 10% intervals and its averaging throughout the whole study period and the whole region, strongly improved (99% of variance accounted) the relationship with ozone concentrations expressed as AOT20 (accumulated over a cut-off of 20 ppb v). N. tabacum cultivar Bel-W3 is thus a very good biomonitor of ozone concentrations in the long term at the regional scale. Taking into account the phytotoxical response of this sensitive tobacco cultivar, we propose the 1.28 ppm v h biweekly AOT40 (with a solar radiation threshold of 50 W m -2) as a damage threshold level for sensitive species.

  1. Nqrs Data for C8H8Cl3N3O4S2 (Subst. No. 1087)

    NASA Astrophysics Data System (ADS)

    Chihara, H.; Nakamura, N.

    This document is part of Subvolume A `Substances Containing Ag … C10H15' of Volume 48 `Nuclear Quadrupole Resonance Spectroscopy Data' of Landolt-Börnstein - Group III `Condensed Matter'. It contains an extract of Section `3.2 Data tables' of the Chapter `3 Nuclear quadrupole resonance data' providing the NQRS data for C8H8Cl3N3O4S2 (Subst. No. 1087)

  2. Ozone impacts of natural gas development in the Haynesville Shale.

    PubMed

    Kemball-Cook, Susan; Bar-Ilan, Amnon; Grant, John; Parker, Lynsey; Jung, Jaegun; Santamaria, Wilson; Mathews, Jim; Yarwood, Greg

    2010-12-15

    The Haynesville Shale is a subsurface rock formation located beneath the Northeast Texas/Northwest Louisiana border near Shreveport. This formation is estimated to contain very large recoverable reserves of natural gas, and during the two years since the drilling of the first highly productive wells in 2008, has been the focus of intensive leasing and exploration activity. The development of natural gas resources within the Haynesville Shale is likely to be economically important but may also generate significant emissions of ozone precursors. Using well production data from state regulatory agencies and a review of the available literature, projections of future year Haynesville Shale natural gas production were derived for 2009-2020 for three scenarios corresponding to limited, moderate, and aggressive development. These production estimates were then used to develop an emission inventory for each of the three scenarios. Photochemical modeling of the year 2012 showed increases in 2012 8-h ozone design values of up to 5 ppb within Northeast Texas and Northwest Louisiana resulting from development in the Haynesville Shale. Ozone increases due to Haynesville Shale emissions can affect regions outside Northeast Texas and Northwest Louisiana due to ozone transport. This study evaluates only near-term ozone impacts, but the emission inventory projections indicate that Haynesville emissions may be expected to increase through 2020. PMID:21086985

  3. Houston's rapid ozone increases: preconditions and geographic origins.

    PubMed

    Couzo, Evan; Jeffries, Harvey E; Vizuete, William

    2013-06-28

    Many of Houston's highest 8-h ozone (O3) peaks are characterised by increases in concentrations of at least 40 ppb in 1 h, or 60 ppb in 2 h. These rapid increases are called non-typical O3 changes (NTOCs). In 2004, the Texas Commission on Environmental Quality (TCEQ) developed a novel emissions control strategy aimed at eliminating NTOCs. The strategy limited routine and short-term emissions of ethene, propene, 1,3-butadiene and butene isomers, collectively called highly reactive volatile organic compounds (HRVOCs), which are released from petrochemical facilities. HRVOCs have been associated with NTOCs through field campaigns and modelling studies. This study analysed wind measurements and O3, formaldehyde (HCHO) and sulfur dioxide (SO2) concentrations from 2000 to 2011 at 25 ground monitors in Houston. NTOCs almost always occurred when monitors were downwind of petrochemical facilities. Rapid O3 increases were associated with low wind speeds; 75 % of NTOCs occurred when the 3-h average wind speed preceding the event was less than 6.5 km h(-1). Statistically significant differences in HCHO concentrations were seen between days with and without NTOCs. Early afternoon HCHO concentrations were greater on NTOC days. In the morning before an observed NTOC event, however, there were no significant differences in HCHO concentrations between days with and without NTOCs. Hourly SO2 concentrations also increased rapidly, exhibiting behaviour similar to NTOCs. Oftentimes, the SO2 increases preceded a NTOC. These findings show that, despite the apparent success of targeted HRVOC emission controls, further restrictions may be needed to eliminate the remaining O3 events. PMID:24014080

  4. Spatiotemporal modelling of ozone distribution in the State of California

    NASA Astrophysics Data System (ADS)

    Bogaert, P.; Christakos, G.; Jerrett, M.; Yu, H.-L.

    This paper is concerned with the spatiotemporal mapping of monthly 8-h average ozone ( O3) concentrations over California during a 15-years period. The basic methodology of our analysis is based on the spatiotemporal random field (S/TRF) theory. We use a S/TRF decomposition model with a dominant seasonal O3 component that may change significantly from site to site. O3 seasonal patterns are estimated and separated from stochastic fluctuations. By means of Bayesian Maximum Entropy (BME) analysis, physically meaningful and sufficiently detailed space-time maps of the seasonal O3 patterns are generated across space and time. During the summer and winter months the seasonal O3 concentration maps exhibit clear and progressively changing geographical patterns over time, suggesting the existence of relationships in accordance with the typical physiographic and climatologic features of California. BME mapping accuracy can be superior to that of other techniques commonly used by EPA; its framework can rigorously assimilate useful data sources that were previously unaccounted for; the generated maps offer valuable assessments of the spatiotemporal O3 patterns that can be helpful in the identification of physical mechanisms and their interrelations, the design of human exposure and population health models, and in risk assessment. As they focus on the seasonal patterns, the maps are not contingent on short-time and locally prevalent weather conditions, which are of no interest in a global and non-forecasting framework. Moreover, the maps offer valuable insight about the space-time O3 concentration patterns and are, thus, helpful for disentangling the influence of explanatory factors or even for identifying some influential ones that could have been otherwise overlooked.

  5. Reconciling NOx emissions reductions and ozone trends in the U.S., 2002-2006

    NASA Astrophysics Data System (ADS)

    Zhou, Wei; Cohan, Daniel S.; Napelenok, Sergey L.

    2013-05-01

    Dynamic evaluation seeks to assess the ability of photochemical models to replicate changes in air quality as emissions and other conditions change. When a model fails to replicate an observed change, a key challenge is to discern whether the discrepancy is caused by errors in meteorological simulations, errors in emission magnitudes and changes, or inaccurate responses of simulated pollutant concentrations to emission changes. In this study, the Community Multiscale Air Quality (CMAQ) model is applied to simulate the ozone (O3) change after the NOx SIP Call and mobile emission controls substantially reduced nitrogen oxides (NOx) emissions in the eastern U.S. from 2002 to 2006. For both modeled and observed O3, changes in episode average daily maximal 8-h O3 were highly correlated (R2 = 0.89) with changes in the 95th percentile, although the magnitudes of reductions increased nonlinearly at high percentile O3 concentrations. Observed downward changes in mean NOx (-11.6 to -2.5 ppb) and 8-h O3 (-10.4 to -4.7 ppb) concentrations in metropolitan areas in the NOx SIP Call region were under-predicted by 31%-64% and 26%-66%, respectively. The under-predicted O3 improvements in the NOx SIP Call region could not be explained by adjusting for temperature biases in the meteorological input, or by considering uncertainties in the chemical reaction rate constants. However, the under-prediction in O3 improvements could be alleviated by 5%-31% by constraining NOx emissions in each year based on observed NOx concentrations. This demonstrates the crucial need to accurately characterize changes in precursor emissions when dynamically evaluating a model's ability to simulate O3 responses to those changes.

  6. Tropospheric ozone in the Nisqually River Drainage, Mount Rainier National Park

    USGS Publications Warehouse

    Peterson, D.L.; Bowers, Darci

    1999-01-01

    We quantified the summertime distribution of tropospheric ozone in the topographically complex Nisqually River drainage of Mount Rainier National Park from 1994 to 1997. Passive ozone samplers were used along an elevational transect to measure weekly average ozone concentrations ranging from 570 m to 2040 m elevation. Weekly average ozone concentrations were positively correlated with elevation, with the highest concentrations consistently measured at the highest sampling site (Panorama Point). Weekly average ozone concentrations at Mount Rainier National Park are considerably higher than those in the Seattle-Tacoma metropolitan area to the west. The anthropogenic contribution to ozone within the Nisqually drainage was evaluated by comparing measurements at this location with measurements from a 'reference' site in the western Olympic Mountains. The comparison suggests there is a significant anthropogenic source of ozone reaching the Cascade Range via atmospheric transport from urban areas to the west. In addition. temporal (week to week) variation in ozone distribution is synchronous within the Nisqually drainage, which indicates that subregional patterns are detectable with weekly averages. The Nisqually drainage is likely the 'hot spot' for air pollution in Mount Rainier National Park. By using passive ozone samplers in this drainage in conjunction with a limited number of continuous analyzers, the park will have a robust monitoring approach for measuring tropospheric ozone over time and protecting vegetative and human health.

  7. Diurnal variations of stratospheric ozone measured by ground-based microwave remote sensing at the Mauna Loa NDACC site: measurement validation and GEOSCCM model comparison

    NASA Astrophysics Data System (ADS)

    Parrish, A.; Boyd, I. S.; Nedoluha, G. E.; Bhartia, P. K.; Frith, S. M.; Kramarova, N. A.; Connor, B. J.; Bodeker, G. E.; Froidevaux, L.; Shiotani, M.; Sakazaki, T.

    2014-07-01

    There is presently renewed interest in diurnal variations of stratospheric and mesospheric ozone for the purpose of supporting homogenization of records of various ozone measurements that are limited by the technique employed to being made at certain times of day. We have made such measurements for 19 years using a passive microwave remote sensing technique at the Mauna Loa Observatory (MLO) in Hawaii, which is a primary station in the Network for Detection of Atmospheric Composition Change (NDACC). We have recently reprocessed these data with hourly time resolution to study diurnal variations. We inspected differences between pairs of the ozone spectra (e.g., day and night) from which the ozone profiles are derived to determine the extent to which they may be contaminated by diurnally varying systematic instrumental or measurement effects. These are small, and we have reduced them further by selecting data that meet certain criteria that we established. We have calculated differences between profiles measured at different times: morning-night, afternoon-night, and morning-afternoon and have intercompared these with like profiles derived from the Aura Microwave Limb Sounder (Aura-MLS), the Upper Atmosphere Research Satellite Microwave Limb Sounder (UARS-MLS), the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES), and Solar Backscatter Ultraviolet version 2 (SBUV/2) measurements. Differences between averages of coincident profiles are typically < 1.5% of typical nighttime values over most of the covered altitude range with some exceptions. We calculated averages of ozone values for each hour from the Mauna Loa microwave data, and normalized these to the average for the first hour after midnight for comparison with corresponding values calculated with the Goddard Earth Observing System Chemistry Climate Model (GEOSCCM). We found that the measurements and model output mostly agree to better than 1.5% of the midnight value, with one noteworthy exception

  8. Polar Ozone Workshop. Abstracts

    NASA Technical Reports Server (NTRS)

    Aikin, Arthur C.

    1988-01-01

    Results of the proceedings of the Polar Ozone Workshop held in Snowmass, CO, on May 9 to 13, 1988 are given. Topics covered include ozone depletion, ozonometry, polar meteorology, polar stratospheric clouds, remote sensing of trace gases, atmospheric chemistry and dynamical simulations.

  9. The Antarctic Ozone Hole.

    ERIC Educational Resources Information Center

    Stolarski, Richard S.

    1988-01-01

    Discusses the Airborne Antarctic Ozone Experiment (1987) and the findings of the British Antarctic Survey (1985). Proposes two theories for the appearance of the hole in the ozone layer over Antarctica which appears each spring; air pollution and natural atmospheric shifts. Illustrates the mechanics of both. Supports worldwide chlorofluorocarbon…

  10. Surface Ozone in Kiev

    NASA Astrophysics Data System (ADS)

    Shavrina, A. V.; Mikulskaya, I. A.; Kiforenko, S. I.; Blum, O. B.; Sheminova, V. A.; Veles, A. A.

    The study of total ozone over Kiev and its concentration changes with height in the troposphere has been made on the base of ground-based observations with the infrared Fourier-spectrometer in the Main Astronomical Observatory of National Academy of Sciences of Ukraine (MAO NASU) as part of ESA-NIVR-KNMI project no 2907 "OMI validation by ground based remote sensing: ozone columns and atmospheric profiles "(2005-2008) [1,2,4]. Ground-level ozone in Kiev for an episode of its high concentrations in August 2000 was also simulated with the model of urban air pollution UAM-V [5,6]. In 2008 the satellite data Aura-OMI on profiles of ozone in the atmosphere OMO3PR became available (http://disc.sci.gsfc.nasa.gov/ Aura/data-holdings/OMI/ omo3pr_v003.shtml). They include ozone content in the lower layer of the atmosphere, beginning from 2005, which can be used to evaluate the ground-level ozone in all cities of Ukraine. The comparison of the data of ozone air pollution in Kiev (ozone - the pollutant of the first class of danger) and medical statistics data of of respiratory system (RS) diseases of the city population was carried out with the package "Statistica". A regression analysis, prognostic regression modelling, and retrospective prognosis of the epidemiological situation with respect to RS pathologies in Kiev in 2000-2006 were performed.

  11. Ozone and temperature trends

    NASA Technical Reports Server (NTRS)

    Stolarski, Richard S.; Fioletov, Vitali; Bishop, Lane; Godin, Sophie; Bojkov, Rumen D.; Kirchhoff, Volker; Chanin, Marie-Lise; Zawodny, Joseph M.; Zerefos, Christos S.; Chu, William

    1991-01-01

    An update of the extensive reviews of the state of knowledge of measured ozone trends published in the Report of the International Ozone Trends Panel is presented. The update contains a review of progress since these reports, including reviewing of the ozone records, in most cases through March 1991. Also included are some new, unpublished reanalyses of these records including a complete reevaluation of 29 stations located in the former Soviet Union. The major new advance in knowledge of the measured ozone trend is the existence of independently calibrated satellite data records from the Total Ozone Mapping Spectrometer (TOMS) and Stratospheric Aerosol and Gas Experiment (SAG) instruments. These confirm many of the findings, originally derived from the Dobson record, concerning northern mid-latitude changes in ozone. We now have results from several instruments, whereas the previously reported changes were dependent on the calibration of a single instrument. This update will compare the ozone records from many different instruments to determine whether or not they provide a consistent picture of the ozone change that has occurred in the atmosphere. The update also briefly considers the problem of stratospheric temperature change. As in previous reports, this problem received significantly less attention, and the report is not nearly as complete. This area needs more attention in the future.

  12. Saving Our Ozone Shield.

    ERIC Educational Resources Information Center

    Lacoste, Beatrice

    1992-01-01

    Discusses the introduction and continued use of chlorofluorocarbons (CFCs) as related to stratospheric ozone depletion. Presents the characteristics of CFCs conducive to the chemical reaction with ozone, the history of CFC use and detection of related environmental problems, health hazards, and alternatives to CFC use. (MCO)

  13. Effect of ozone and histamine on airway permeability to horseradish peroxidase in guinea pigs

    SciTech Connect

    Miller, P.D.; Gordon, T.; Warnick, M.; Amdur, M.O.

    1986-01-01

    Airway permeability was studied in groups of male guinea pigs at 2, 8, and 24 h after a 1-h exposure to 1 ppm ozone or at 2 h after a 1-h exposure to filtered air (control). Intratracheal administration of 2 mg horseradish peroxidase (HRP) was followed by blood sampling at 5-min intervals up to 30 min. The rate of appearance of HRP in plasma was significantly higher at 2 and 8 h after ozone exposure than that found in animals examined 2 h after air exposure or 24 h after ozone exposure. A dose of 0.12 mg/kg of subcutaneous histamine given after the 15 min blood sample significantly increased the already elevated permeability seen at 2 h post ozone, but had no effect on animals exposed to filtered air 2 h earlier or to ozone 24 h earlier. No difference was seen in the amount of subcutaneous radiolabeled histamine in the lungs of animals exposed 2 h earlier either to air or to ozone. These data indicate that a short-term exposure to ozone produced a reversible increase in respiratory epithelial permeability to HRP in guinea pigs. The potentiation of this increased permeability by histamine may be another manifestation of ozone-induced hyperreactivity.

  14. Observing trends in total ozone and extreme ozone events

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2014-05-01

    The ozone layer in the stratosphere has been recovering since the 1989 Montreal Protocol reduced the use of ozone-destroying chlorofluorocarbons. Fitzka et al. observed trends in total ozone levels and the vertical distribution of ozone at Hoher Sonnblick, a mountain in Austria, from 1994 to 2011.

  15. Surface Ozone Dynamics in the Kola Peninsula Region

    NASA Astrophysics Data System (ADS)

    Beloglazov, M. I.; Karpechko, A. Yu.; Nikulin, G. N.; Roumjantsev, S. A.

    Measurements of surface ozone from the centre of the Murmansk Region (Apatity, Kola peninsula) and its southern part (Kovda, White Sea coast) give a picture of the behaviour of this air component on the Kola peninsula and surrounding vicinity. Simultaneous measurements in Apatity and Kovda have shown that the ozone concentration in Apatity is roughly twice as much as in Kovda. This fact may be explained by the local wind circulation and the presence of bromine near the coast of the Kola Peninsula. An inverse correlation is found between the ozone and nitrogen oxide concentrations from observations near motorways in Apatity. A decrease of nitrogen oxide concentration accompanies the growth of ozone on average. Thus, Apatity is a northern city in which the air pollution by traffic emissions decreases the ozone content.

  16. Estimating contribution of wildland fires to ambient ozone levels in National Parks in the Sierra Nevada, California.

    PubMed

    Preisler, Haiganoush K; Zhong, Shiyuan Sharon; Esperanza, Annie; Brown, Timothy J; Bytnerowicz, Andrzej; Tarnay, Leland

    2010-03-01

    Data from four continuous ozone and weather monitoring sites operated by the National Park Service in Sierra Nevada, California, are used to develop an ozone forecasting model and to estimate the contribution of wildland fires on ambient ozone levels. The analyses of weather and ozone data pointed to the transport of ozone precursors from the Central Valley as an important source of pollution in these National Parks. Comparisons of forecasted and observed values demonstrated that accurate forecasts of next-day hourly ozone levels may be achieved by using a time series model with historic averages, expected local weather and modeled PM values as explanatory variables. Results on fire smoke influence indicated occurrence of significant increases in average ozone levels with increasing fire activity. The overall effect on diurnal ozone values, however, was small when compared with the amount of variability attributed to sources other than fire. PMID:19914752

  17. The 2010 Antarctic ozone hole: Observed reduction in ozone destruction by minor sudden stratospheric warmings

    PubMed Central

    de Laat, A. T. J.; van Weele, M.

    2011-01-01

    Satellite observations show that the 2010 Antarctic ozone hole is characterized by anomalously small amounts of photochemical ozone destruction (40-60% less than the 2005-2009 average). Observations from the MLS instrument show that this is mainly related to reduced photochemical ozone destruction between 20-25 km altitude. Lower down between 15-20 km the atmospheric chemical composition and photochemical ozone destruction is unaffected. The modified chemical composition and chemistry between 20-25 km altitude in 2010 is related to the occurrence of a mid-winter minor Antarctic Sudden Stratospheric Warming (SSW). The measurements indicate that the changes in chemical composition are related to downward motion of air masses rather than horizontal mixing, and affect stratospheric chemistry for several months. Since 1979, years with similar anomalously small amounts of ozone destruction are all characterized by either minor or major SSWs, illustrating that their presence has been a necessary pre-condition for reduced Antarctic stratospheric ozone destruction. PMID:22355557

  18. The 2010 Antarctic ozone hole: observed reduction in ozone destruction by minor sudden stratospheric warmings.

    PubMed

    de Laat, A T J; van Weele, M

    2011-01-01

    Satellite observations show that the 2010 Antarctic ozone hole is characterized by anomalously small amounts of photochemical ozone destruction (40-60% less than the 2005-2009 average). Observations from the MLS instrument show that this is mainly related to reduced photochemical ozone destruction between 20-25 km altitude. Lower down between 15-20 km the atmospheric chemical composition and photochemical ozone destruction is unaffected. The modified chemical composition and chemistry between 20-25 km altitude in 2010 is related to the occurrence of a mid-winter minor Antarctic Sudden Stratospheric Warming (SSW). The measurements indicate that the changes in chemical composition are related to downward motion of air masses rather than horizontal mixing, and affect stratospheric chemistry for several months. Since 1979, years with similar anomalously small amounts of ozone destruction are all characterized by either minor or major SSWs, illustrating that their presence has been a necessary pre-condition for reduced Antarctic stratospheric ozone destruction. PMID:22355557

  19. On the Berdichevsky average

    NASA Astrophysics Data System (ADS)

    Rung-Arunwan, Tawat; Siripunvaraporn, Weerachai; Utada, Hisashi

    2016-04-01

    Through a large number of magnetotelluric (MT) observations conducted in a study area, one can obtain regional one-dimensional (1-D) features of the subsurface electrical conductivity structure simply by taking the geometric average of determinant invariants of observed impedances. This method was proposed by Berdichevsky and coworkers, which is based on the expectation that distortion effects due to near-surface electrical heterogeneities will be statistically smoothed out. A good estimation of a regional mean 1-D model is useful, especially in recent years, to be used as a priori (or a starting) model in 3-D inversion. However, the original theory was derived before the establishment of the present knowledge on galvanic distortion. This paper, therefore, reexamines the meaning of the Berdichevsky average by using the conventional formulation of galvanic distortion. A simple derivation shows that the determinant invariant of distorted impedance and its Berdichevsky average is always downward biased by the distortion parameters of shear and splitting. This means that the regional mean 1-D model obtained from the Berdichevsky average tends to be more conductive. As an alternative rotational invariant, the sum of the squared elements (ssq) invariant is found to be less affected by bias from distortion parameters; thus, we conclude that its geometric average would be more suitable for estimating the regional structure. We find that the combination of determinant and ssq invariants provides parameters useful in dealing with a set of distorted MT impedances.

  20. Averaging the inhomogeneous universe

    NASA Astrophysics Data System (ADS)

    Paranjape, Aseem

    2012-03-01

    A basic assumption of modern cosmology is that the universe is homogeneous and isotropic on the largest observable scales. This greatly simplifies Einstein's general relativistic field equations applied at these large scales, and allows a straightforward comparison between theoretical models and observed data. However, Einstein's equations should ideally be imposed at length scales comparable to, say, the solar system, since this is where these equations have been tested. We know that at these scales the universe is highly inhomogeneous. It is therefore essential to perform an explicit averaging of the field equations in order to apply them at large scales. It has long been known that due to the nonlinear nature of Einstein's equations, any explicit averaging scheme will necessarily lead to corrections in the equations applied at large scales. Estimating the magnitude and behavior of these corrections is a challenging task, due to difficulties associated with defining averages in the context of general relativity (GR). It has recently become possible to estimate these effects in a rigorous manner, and we will review some of the averaging schemes that have been proposed in the literature. A tantalizing possibility explored by several authors is that the corrections due to averaging may in fact account for the apparent acceleration of the expansion of the universe. We will explore this idea, reviewing some of the work done in the literature to date. We will argue however, that this rather attractive idea is in fact not viable as a solution of the dark energy problem, when confronted with observational constraints.

  1. The Hole in the Ozone Layer.

    ERIC Educational Resources Information Center

    Hamers, Jeanne S.; Jacob, Anthony T.

    This document contains information on the hole in the ozone layer. Topics discussed include properties of ozone, ozone in the atmosphere, chlorofluorocarbons, stratospheric ozone depletion, effects of ozone depletion on life, regulation of substances that deplete the ozone layer, alternatives to CFCs and Halons, and the future of the ozone layer.…

  2. The Two Faces of Ozone.

    ERIC Educational Resources Information Center

    Monastersky, Richard

    1989-01-01

    Provides answers to questions regarding the ozone problem: (1) nature of ozone in the troposphere and stratosphere; (2) possibility of sending the excess ozone at ground level to the stratosphere; (3) possibility of producing pure ozone and carrying it to the stratosphere; and (4) banning chlorofluorocarbons. (YP)

  3. Fundamentals of ISCO Using Ozone

    EPA Science Inventory

    In situ chemical oxidation (ISCO) using ozone involves the introduction of ozone gas (O3) into the subsurface to degrade organic contaminants of concern. Ozone is tri-molecular oxygen (O2) that is a gas under atmospheric conditions and is a strong oxidant. Ozone may react with ...

  4. Ozone measurements in Amazonia: Dry season versus wet season

    SciTech Connect

    Kirchhoff, V.W.J.H. ); Da Silva, I.M.O. ); Browell, E.V. )

    1990-09-20

    Observations were made almost continuously at the surface, and in addition, 20 ozone profiles were obtained in the troposphere and stratosphere. These ozone measurements were part of a field expedition to the Brazilian Amazon region, the ABLE 2B mission, a joint American-Brazilian effort to measure local concentrations of several species relevant to atmospheric chemistry. The time period of this expedition was April-May 1987, during the local wet season. For the surface ozone data the measurement technique sued was UV absorption. Ozone profiles were obtained with electrochemical concentration cell sondes, launched on balloons. The major site of operation was set up near Manaus (3{degree}S, 60{degree}W). The results are presented and compared with a previous dry season experiment. Surface ozone mixing ratios show diurnal variations that have maxima in the daytime and minima at night. The diurnal maximum at noontime, considered very low (12 ppbv) in the dry season was even lower in this wet season period (6 ppbv). A significant difference can be seen between clearing and forest data, and between different height levels above the surface, showing the existence of a large positive gradient of ozone with height. The ozone profiles in the troposphere show that there is less ozone not only at the surface but in the whole troposphere, with the wet season average showing between 6 and 12 ppbv less ozone. This difference is much smaller in the stratosphere, where there is slightly more ozone in the region of the peak, during the wet season. An isolated shower or thunderstorm in the dry season could produce transient ozone variations (mixing ratio increases or decreases) that were not observed in the wet season.

  5. The Role of Galveston Bay Meteorology in Ozone Concentrations in Houston, Texas

    NASA Astrophysics Data System (ADS)

    Nielsen-Gammon, J. W.; Tobin, J.

    2007-12-01

    Galveston Bay is a body of water approximately 50 km by 30 km that opens into the Gulf of Mexico. The head of Galveston Bay is adjacent to the Houston Ship Channel, where large industrial emitters of ozone precursors are located. We consider the role of coastal circulations and mixing suppression over Galveston Bay in the location and magnitude of peak 8-h ozone values at monitors within the Houston-Galveston-Brazoria nonattainment area. Galveston Bay is found to have a salutary effect on ozone concentrations under most circumstances. Aside from boats and ships, Galveston Bay is free of ozone precursor emissions, and the onset of the sea breeze along Galveston Bay usually causes an immediate drop in ozone levels. The situation changes dramatically when the morning wind direction is from the northwest, allowing ozone precursors emitted during the night or early morning that are distributed in a shallow atmospheric layer to be carried over Galveston Bay. In morning and early afternoon, mixing is suppressed over Galveston Bay, and precursor concentrations remain high in the absence of ventilation. If winds are strong, high ozone concentrations are generally observed along the far shore of Galveston Bay. If winds are weak, a sea breeze will develop along Galveston Bay, and high levels of ozone will be carried back onshore in the vicinity of the Ship Channel. The coastal oscillation (a regular rotation of the wind vector driving by coastal heating contrasts near 30 N) can lead to wind reversals and high values of ozone by itself. We investigate peak ozone concentrations under a variety of wind conditions to infer whether the ozone concentrations are, on balance, higher due to the net effect of meteorological processes associated with Galveston Bay.

  6. ALTERNATIVE OZONE DOSE METRICS TO CHARACTERIZE OZONE IMPACT ON CROP YIELD LOSS (JOURNAL VERSION)

    EPA Science Inventory

    Previous studies of the National Crop Loss Assessment Network (NCLAN) relating the impact of ozone (O3) on agricultural crops have used the seasonal arithmetic average of O3 for either a 7- or 12-h daily period as the measure of dose in the dose response relationships. The study ...

  7. Raman spectroscopic study of the minerals apophyllite-(KF) KCa4Si8O20F·8H2O and apophyllite-(KOH) KCa4Si8O20(F,OH)·8H2O

    NASA Astrophysics Data System (ADS)

    Frost, Ray L.; Xi, Yunfei

    2012-11-01

    Raman spectroscopy complimented with infrared spectroscopy has been used to study the variation in molecular structure of two minerals of the apophyllite mineral group, namely apophyllite-(KF) KCa4Si8O20F·8H2O and apophyllite-(KOH) KCa4Si8O20(F,OH)·8H2O. apophyllite-(KF) and apophyllite-(KOH) are different minerals only because of the difference in the percentage of fluorine to hydroxyl ions. The Raman spectra are dominated by a very intense sharp peak at 1059 cm-1. A band at around 846 cm-1 is assigned to the water librational mode. It is proposed that the difference between apophyllite-(KF) and apophyllite-(KOH) is the observation of two Raman bands in the OH stretching region at around 3563 and 3625 cm-1. Multiple water stretching and bending modes are observed showing that there is much variation in hydrogen bonding between water and the silicate surfaces.

  8. Utilization of 100 mb midlatitude height fields as an indicator of sampling effects on total ozone variations

    NASA Technical Reports Server (NTRS)

    Miller, A. J.; Nagatani, R. M.; Laver, J. D.; Korty, B.

    1979-01-01

    Midlatitude 100-mb height fields are employed to determine the effects of ground based sampling locations on measurements of variations in the total ozone content of the atmosphere. The precision of the zonal average heights computed by the technique of Angell and Korshover (1978) from data over ozone sampling areas at 50 deg N is compared to the zonal average computed from the entire data set. Linear regressions of ozone contents determined by an analysis of backscatter UV satellite data with respect to 100 mb heights are utilized to transform zonal differences in height to ozone levels. The zonal average total ozone sampling error is found to be on the order of 2% for midlatitudes of the Northern hemisphere, indicating that the general shape of ozone trends determined by ground-based observations appears to be real and the increase of ozone from the mid-1960's to the early 1970's may be greater than previously suggested.

  9. Estimating when the Antarctic Ozone Hole will Recover

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.; Nash, Eric R.; Douglass, Anne R.; Nielsen, J. Eric; Pawson, Steven; Stolarski, Richard S.

    2007-01-01

    The Antarctic ozone hole develops each year and culminates by early spring (late September - early October). The severity of the hole has been assessed from satellites using the minimum total ozone value from the October monthly mean (depth of the hole) and by calculating the average area coverage during this September-October period. Profile information shows that ozone is completely destroyed in the 14-2 1 km layer by early October. Ozone is mainly destroyed by halogen (chlorine and bromine) catalytic cycles, and these losses are modulated by temperature variations. Because atmospheric halogen levels are responding to international a'greements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. Using projections of halogen levels combined with age-of-air estimates, we find that the ozone hole is recovering at an extremely slow rate and that large ozone holes will regularly recur over the next 2 decades. We estimate that the ozone hole will begin to show first signs of size decrease in about 2023, and the hole will fully recover to pre-1980 levels in approximately 2070. Estimates of the ozone hole's recovery from models reveal important differences that will be discussed.

  10. Estimating When the Antarctic Ozone Hole Will Recover

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.; Nash, Eric R.; Douglass, Anne R.; Nielsen, J. Eric; Pawson, Steven; Stolarski, Richard S.

    2007-01-01

    The Antarctic ozone hole develops each year and culminates by early spring (late September - early October). The severity of the hole has been assessed from satellites using the minimum total ozone value from the October monthly mean (depth of the hole) and by calculating the average area coverage during this September-October period. Profile information shows that ozone is completely destroyed in the 14-21 km layer by early October. Ozone is mainly destroyed by halogen (chlorine and bromine) catalytic cycles, and these losses are modulated by temperature variations. Because atmospheric halogen levels are responding to international agreements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. Using projections of halogen levels combined with age-of-air estimates, we find that the ozone hole is recovering at an extremely slow rate and that large ozone holes will regularly recur over the next 2 decades. We estimate that the ozone hole will begin to show first signs of size decrease in about 2023, and the hole will fully recover to pre-1980 levels in approximately 2070. Estimates of the ozone hole's recovery from models reveal important differences that will be discussed.

  11. Lagrangian Transport Calculations Using UARS Data. Part 2; Ozone

    NASA Technical Reports Server (NTRS)

    Manney, Gloria L.; Zurek, R. W.; Froidevaux, L.; Waters, J. W.; ONeill, A.; Swinbank, R.

    1995-01-01

    Trajectory calculations are used to examine ozone transport in the polar winter stratosphere during periods of the Upper Atmosphere Research Satellite (UARS) observations. The value of these calculations for determining mass transport was demonstrated previously using UARS observations of long-lived tracers, In the middle stratosphere, the overall ozone behavior observed by the Microwave Limb Sounder in the polar vortex is reproduced by this purely dynamical model. Calculations show the evolution of ozone in the lower stratosphere during early winter to be dominated by dynamics in December 1992 in the Arctic. Calculations for June 1992 in the Antarctic show evidence of chemical ozone destruction and indicate that approx. 50% of the chemical destruction may be masked by dynamical effects, mainly diabatic descent, which bring higher ozone into the lower-stratospheric vortex. Estimating differences between calculated and observed fields suggests that dynamical changes masked approx. 20% - 35% of chemical ozone loss during late February and early March 1993 in the Arctic. In the Antarctic late winter, in late August and early September 1992, below approx. 520 K, the evolution of vortex-averaged ozone is entirely dominated by chemical effects; above this level, however, chemical ozone depletion can be partially or completely masked by dynamical effects. Our calculations for 1992 showed that chemical loss was nearly completely compensated by increases due to diabatic descent at 655 K.

  12. Stratospheric ozone depletion

    PubMed Central

    Rowland, F. Sherwood

    2006-01-01

    Solar ultraviolet radiation creates an ozone layer in the atmosphere which in turn completely absorbs the most energetic fraction of this radiation. This process both warms the air, creating the stratosphere between 15 and 50 km altitude, and protects the biological activities at the Earth's surface from this damaging radiation. In the last half-century, the chemical mechanisms operating within the ozone layer have been shown to include very efficient catalytic chain reactions involving the chemical species HO, HO2, NO, NO2, Cl and ClO. The NOX and ClOX chains involve the emission at Earth's surface of stable molecules in very low concentration (N2O, CCl2F2, CCl3F, etc.) which wander in the atmosphere for as long as a century before absorbing ultraviolet radiation and decomposing to create NO and Cl in the middle of the stratospheric ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the stratosphere, with the result that more solar ultraviolet-B radiation (290–320 nm wavelength) reaches the surface. This ozone loss occurs in the temperate zone latitudes in all seasons, and especially drastically since the early 1980s in the south polar springtime—the ‘Antarctic ozone hole’. The chemical reactions causing this ozone depletion are primarily based on atomic Cl and ClO, the product of its reaction with ozone. The further manufacture of chlorofluorocarbons has been banned by the 1992 revisions of the 1987 Montreal Protocol of the United Nations. Atmospheric measurements have confirmed that the Protocol has been very successful in reducing further emissions of these molecules. Recovery of the stratosphere to the ozone conditions of the 1950s will occur slowly over the rest of the twenty-first century because of the long lifetime of the precursor molecules. PMID:16627294

  13. Stratospheric ozone depletion.

    PubMed

    Rowland, F Sherwood

    2006-05-29

    Solar ultraviolet radiation creates an ozone layer in the atmosphere which in turn completely absorbs the most energetic fraction of this radiation. This process both warms the air, creating the stratosphere between 15 and 50 km altitude, and protects the biological activities at the Earth's surface from this damaging radiation. In the last half-century, the chemical mechanisms operating within the ozone layer have been shown to include very efficient catalytic chain reactions involving the chemical species HO, HO2, NO, NO2, Cl and ClO. The NOX and ClOX chains involve the emission at Earth's surface of stable molecules in very low concentration (N2O, CCl2F2, CCl3F, etc.) which wander in the atmosphere for as long as a century before absorbing ultraviolet radiation and decomposing to create NO and Cl in the middle of the stratospheric ozone layer. The growing emissions of synthetic chlorofluorocarbon molecules cause a significant diminution in the ozone content of the stratosphere, with the result that more solar ultraviolet-B radiation (290-320 nm wavelength) reaches the surface. This ozone loss occurs in the temperate zone latitudes in all seasons, and especially drastically since the early 1980s in the south polar springtime-the 'Antarctic ozone hole'. The chemical reactions causing this ozone depletion are primarily based on atomic Cl and ClO, the product of its reaction with ozone. The further manufacture of chlorofluorocarbons has been banned by the 1992 revisions of the 1987 Montreal Protocol of the United Nations. Atmospheric measurements have confirmed that the Protocol has been very successful in reducing further emissions of these molecules. Recovery of the stratosphere to the ozone conditions of the 1950s will occur slowly over the rest of the twenty-first century because of the long lifetime of the precursor molecules. PMID:16627294

  14. Ozone - plant surface reactions an important ozone loss term?

    NASA Astrophysics Data System (ADS)

    Hansel, Armin; Jud, Werner; Fischer, Lukas; Canaval, Eva; Wohlfahrt, Georg; Tissier, Alain

    2015-04-01

    Elevated tropospheric ozone concentrations are considered a toxic threat to plants responsible for global crop losses with associated economic costs of several billions dollar per year. Plant injuries have been related to the uptake of ozone through stomatal pores and oxidative effects damaging the internal leaf tissue. But a striking question remains: How much ozone enters the plant through open stomata and how much ozone is lost by chemical reactions at the plant surface? Until now surface losses are estimated from measured total ozone deposition fluxes and calculated stomatal conductance values. While stomatal conductance of CO2 and H2O is well understood and extensively used in describing plant atmosphere gas exchange, stomatal conductance of ozone is not well known. Here we use different Nicotiana tabacum varieties and find that surface reactions of ozone with diterpenoids synthesized by glandular trichomes reduce ozone flux through open stomata. Our measurements reveal that fast ozone loss at the plant surface is accompanied with prompt release of oxygenated volatile compounds. In the ozone fumigation experiments of different Nicotiana tabacum varieties the release of specific volatile oxy-VOCs allowed to identify the semi volatile precursor compounds at the plant surface. Ozone fumigation experiments with Norway spruce (Picea abies) and Scots Pine (Pinus sylvestris), two common species in the Northern Hemisphere, show also a significant ozone loss at the plant surface for Picea abies. Fluid dynamic calculations of ozone transport in the diffusive leaf boundary layer reveal a vertical but no horizontal ozone gradient thus reducing ozone fluxes through the pores in case of efficient ozone scavenging plant surfaces. We explain this efficient ozone protection mechanism by the porous surface architecture of plants in combination with unsaturated semi-volatile compounds deposited at the plant surface. These results show that unsaturated semi-volatile compounds at

  15. Projected risk of high ozone episodes in 2050

    NASA Astrophysics Data System (ADS)

    Lei, Hang; Wuebbles, Donald J.; Liang, Xin-Zhong

    2012-11-01

    We investigate the effects of projected global changes in climate and human-related emissions for the year 2050 relative to 2000 for trends in the potential risk of hazardous ozone pollution episodes using a global climate chemistry model, CAM-Chem, driven by meteorology output from Community Climate System Model 3. Three distinct pathways from the Intergovernmental Panel on Climate Change Special Report on Emissions Scenarios A1FI, A1B and B1 are considered to address the range and uncertainty in projected climate and emission changes. The projected changes in extreme climate conditions are likely to intensify the associated extreme weather conditions that foster the risk of high ozone pollution episodes over many parts of the world. It is found that the changes in regional high surface ozone concentration by 2050 largely depends on changes in the anthropogenic emissions of ozone precursors. Our analysis under projected climate and emissions on the frequency of “hazardous ozone days” in which the peak ozone concentration exceed the limit in the summer of 2050, based on 8 and 1-h standards, show that the risk of hazardous ozone pollution episodes will likely increase in developing regions, but changes of risk in developed regions depend on scenarios. For three major pollutant regions, north America, Europe and East Asia under 8-h definition, the hazardous risk in all regions increases under the A1FI scenario with a potential rate of 39-79 days/summer by 2050, but it is likely to decrease over North America and Europe under the A1B and B1 scenarios. The risk on Europe under the A1B and B1 scenarios can be ignored, but a significant rate of 6-71 days/summer still occur on other regions. The relative variability in projected frequency of hazardous ozone days increase by using the 1-h definition, although it shows the highest risk of 17-59 days/summer under the A1FI scenario. The higher variability can be understood through statistical analysis of cumulative

  16. Low density solid ozone

    SciTech Connect

    Teolis, B. D.; Fama, M.; Baragiola, R. A.

    2007-08-21

    We report a very low density ({approx}0.5 g/cm{sup 3}) structure of solid ozone. It is produced by irradiation of solid oxygen with 100 keV protons at 20 K followed by heating to sublime unconverted oxygen. Upon heating to 47 K the porous ozone compacts to a density of {approx}1.6 g/cm{sup 3} and crystallizes. We use a detailed analysis of the main infrared absorption band of the porous ozone to interpret previous research, where solid oxygen was irradiated by UV light and keV electrons.

  17. Arctic ozone loss

    SciTech Connect

    Zurer, P.S.

    1989-03-06

    Scientists have returned from the first comprehensive probe of the Arctic stratosphere with unexpectedly dire results: The winter atmosphere in the north polar region is loaded with the same destructive chlorine compounds that cause the Antarctic ozone hole. Atmospheric researchers who only a few weeks ago were comforted by the thought that the warmer Northern Hemisphere is strongly protected from the processes that lead to massive losses of ozone during spring in Antarctica now see very little standing in the way of an Arctic ozone hole.

  18. Lidar-derived Correlations Between Lower-tropospheric Column and Surface Ozone: Implications for Satellite Observations

    NASA Astrophysics Data System (ADS)

    Senff, C. J.; Langford, A. O.; Alvarez, R. J. _II, II; Kirgis, G.; Choukulkar, A.; Brewer, A.; Banta, R. M.; Weickmann, A. M.; Sandberg, S.; Olson, E.

    2015-12-01

    One of the data products that will be provided by the TEMPO satellite mission is 0-2 km ozone column concentration. To make inferences about surface air quality from this data product, the relationship between lower-tropospheric column and surface ozone concentrations and their diurnal, seasonal, and spatial variations have to be well understood. To characterize these relationships, we have used ozone profile observations obtained with NOAA's truck-based, scanning TOPAZ ozone lidar from several recent field campaigns including Discover-AQ Houston and Colorado, the Uintah Basin Wintertime Ozone Study (UBWOS), and the Las Vegas Ozone Study (LVOS). The TOPAZ lidar is ideally suited for this kind of study because it provides ozone profiles from about 15 m above ground level (AGL) up to 3 km AGL at high spatial and temporal resolution. We have used the lidar observations closest to the ground as a proxy for surface ozone and compared them to the 0-2 km AGL average column ozone concentrations measured with the lidar. Results from the Discover-AQ Colorado campaign show that in the afternoon, when the boundary layer (BL) was deep and well mixed, ozone column and surface concentrations agreed quite well. However, during the morning hours, ozone column concentrations were significantly higher than those at the surface, because ozone was depleted in a shallow surface layer due to titration and deposition, whereas ozone levels in the residual layer aloft remained moderately high. The analysis of column and surface ozone correlations using ozone lidar observations from the Discover-AQ Houston, UBWOS and LVOS campaigns is currently underway. The results from these studies will provide additional insights into the relationship between column and surface ozone, in particular their variation as a function of measurement location and season, and their dependence on BL processes such as mixed layer height evolution, land-sea breeze circulation, and terrain-induced flows.

  19. Variability and sources of surface ozone at rural sites in Nevada, USA: Results from two years of the Nevada Rural Ozone Initiative.

    PubMed

    Fine, Rebekka; Miller, Matthieu B; Burley, Joel; Jaffe, Daniel A; Pierce, R Bradley; Lin, Meiyun; Gustin, Mae Sexauer

    2015-10-15

    Ozone (O3) has been measured at Great Basin National Park (GBNP) since September 1993. GBNP is located in a remote, rural area of eastern Nevada. Data indicate that GBNP will not comply with a more stringent National Ambient Air Quality Standard (NAAQS) for O3, which is based upon the 3-year average of the annual 4th highest Maximum Daily 8-h Average (MDA8) concentration. Trend analyses for GBNP data collected from 1993 to 2013 indicate that MDA8 O3 increased significantly for November to February, and May. The greatest increase was for May at 0.38, 0.35, and 0.46 ppb yr(-1) for the 95th, 50th, and 5th percentiles of MDA8 O3 values, respectively. With the exception of GBNP, continuous O3 monitoring in Nevada has been limited to the greater metropolitan areas. Due to the limited spatial detail of O3 measurements in rural Nevada, a network of rural monitoring sites was established beginning in July 2011. For a period ranging from July 2011 to June 2013, maximum MDA8 O3 at 6 sites occurred in the spring and summer, and ranged from 68 to 80ppb. Our analyses indicate that GBNP, in particular, is ideally positioned to intercept air containing elevated O3 derived from regional and global sources. For the 2 year period considered here, MDA8 O3 at GBNP was an average of 3.1 to 12.6 ppb higher than at other rural Nevada sites. Measured MDA8 O3 at GBNP exceeded the current regulatory threshold of 75 ppb on 7 occasions. Analyses of synoptic conditions, model tracers, and air mass back-trajectories on these days indicate that stratospheric intrusions, interstate pollution transport, wildfires, and Asian pollution contributed to elevated O3 observed at GBNP. We suggest that regional and global sources of ozone may pose challenges to achieving a more stringent O3 NAAQS in rural Nevada. PMID:25548133

  20. Role of neutrophilic inflammation in ozone-induced epithelial alterations in the nasal airways of rats

    NASA Astrophysics Data System (ADS)

    Cho, Hye Youn

    Ozone is a principal oxidant air pollutant in photochemical smog. Epithelial cells lining the centriacinar region of lung and the proximal aspects of nasal passage are primary target sites for ozone-induced injury in laboratory animals. Acute exposure of rats to high ambient concentrations of ozone (e.g., 0.5 ppm) results in neutrophilic inflammation, epithelial hyperplasia and mucous cell metaplasia (MCM) in the nasal transitional epithelium (NTE) lining the proximal nasal airways. The principal purpose of the present study was to investigate the role of pre-metaplastic cellular responses, especially neutrophilic inflammation, in the pathogenesis of ozone-induced MCM in rat NTE. For this purpose, three specific hypotheses-based whole-animal inhalation studies were conducted. Male F344/N rats were exposed in whole-body inhalation chambers to 0 (filtered air) or 0.5 ppm ozone for 1-3 days (8 h/day). Histochemical, immunochemical, molecular and morphometric techniques were used to investigate the ozone-induced cellular and molecular events in the NTE. Two in vitro studies were also conducted to examine the effects of ozone-inducible cytokines (i.e., tumor necrosis factor-alpha; TNF- a, and interleukin-6; IL-6) on mucin gene (rMuc-5AC) expression. Ozone induced a rapid increase of rMuc-5AC mRNA in nasal tissues within hours after the start of exposure. It preceded the appearance of MCM, and persisted with MCM. Ozone-induced neutrophilic inflammation accompanied the mucin gene upregulation, but was resolved when MCM first appeared in the NTE. Antibody-mediated depletion of circulating neutrophils attenuated ozone-induced MCM, although it did not affect the ozone-induced epithelial hyperplasia and mucin mRNA upregulation. In another study, it was found that preexisting neutrophilic rhinitis induced by endotoxin augmented the ozone-induced MCM. However, pre-existing rhinitis did not alter the severity of ozone-induced epithelial hyperplasia and mucin gene upregulation

  1. Covariant approximation averaging

    NASA Astrophysics Data System (ADS)

    Shintani, Eigo; Arthur, Rudy; Blum, Thomas; Izubuchi, Taku; Jung, Chulwoo; Lehner, Christoph

    2015-06-01

    We present a new class of statistical error reduction techniques for Monte Carlo simulations. Using covariant symmetries, we show that correlation functions can be constructed from inexpensive approximations without introducing any systematic bias in the final result. We introduce a new class of covariant approximation averaging techniques, known as all-mode averaging (AMA), in which the approximation takes account of contributions of all eigenmodes through the inverse of the Dirac operator computed from the conjugate gradient method with a relaxed stopping condition. In this paper we compare the performance and computational cost of our new method with traditional methods using correlation functions and masses of the pion, nucleon, and vector meson in Nf=2 +1 lattice QCD using domain-wall fermions. This comparison indicates that AMA significantly reduces statistical errors in Monte Carlo calculations over conventional methods for the same cost.

  2. Average density in cosmology

    SciTech Connect

    Bonnor, W.B.

    1987-05-01

    The Einstein-Straus (1945) vacuole is here used to represent a bound cluster of galaxies embedded in a standard pressure-free cosmological model, and the average density of the cluster is compared with the density of the surrounding cosmic fluid. The two are nearly but not quite equal, and the more condensed the cluster, the greater the difference. A theoretical consequence of the discrepancy between the two densities is discussed. 25 references.

  3. Energetic particle precipitation: A major driver of the ozone budget in the Antarctic upper stratosphere

    NASA Astrophysics Data System (ADS)

    Damiani, Alessandro; Funke, Bernd; Santee, Michelle L.; Cordero, Raul R.; Watanabe, Shingo

    2016-04-01

    Geomagnetic activity is thought to affect ozone and, possibly, climate in polar regions via energetic particle precipitation (EPP) but observational evidence of its importance in the seasonal stratospheric ozone variation on long time scales is still lacking. Here we fill this gap by showing that at high southern latitudes, late winter ozone series, covering the 1979-2014 period, exhibit an average stratospheric depletion of about 10-15% on a monthly basis caused by EPP. Daily observations indicate that every austral winter EPP-induced low ozone concentrations appear at about 45 km in late June and descend later to 30 km, before disappearing by September. Such stratospheric variations are coupled with mesospheric ozone changes also driven by EPP. No significant correlation between these ozone variations and solar ultraviolet irradiance has been found. This suggests the need of including the EPP forcing in both ozone model simulations and trend analysis.

  4. Ozone Therapy in Dentistry

    PubMed Central

    Domb, William C

    2014-01-01

    Summary The 21st century dental practice is quite dynamic. New treatment protocols and new materials are being developed at a rapid pace. Ozone dental therapy falls into the category of new treatment protocols in dentistry, yet ozone is not new at all. Ozone therapy is already a major treatment modality in Europe, South America and a number of other countries. What is provided here will not be an exhaustive scientific treatise so much as a brief general introduction into what dentists are now doing with ozone therapies and the numerous oral/systemic links that make this subject so important for physicians so that, ultimately, they may serve their patients more effectively and productively. PMID:25363268

  5. Comparison of background ozone estimates over the western United States based on two separate model methodologies

    NASA Astrophysics Data System (ADS)

    Dolwick, Pat; Akhtar, Farhan; Baker, Kirk R.; Possiel, Norm; Simon, Heather; Tonnesen, Gail

    2015-05-01

    Two separate air quality model methodologies for estimating background ozone levels over the western U.S. are compared in this analysis. The first approach is a direct sensitivity modeling approach that considers the ozone levels that would remain after certain emissions are entirely removed (i.e., zero-out modeling). The second approach is based on an instrumented air quality model which tracks the formation of ozone within the simulation and assigns the source of that ozone to pre-identified categories (i.e., source apportionment modeling). This analysis focuses on a definition of background referred to as U.S. background (USB) which is designed to represent the influence of all sources other than U.S. anthropogenic emissions. Two separate modeling simulations were completed for an April-October 2007 period, both focused on isolating the influence of sources other than domestic manmade emissions. The zero-out modeling was conducted with the Community Multiscale Air Quality (CMAQ) model and the source apportionment modeling was completed with the Comprehensive Air Quality Model with Extensions (CAMx). Our analysis shows that the zero-out and source apportionment techniques provide relatively similar estimates of the magnitude of seasonal mean daily 8-h maximum U.S. background ozone at locations in the western U.S. when base case model ozone biases are considered. The largest differences between the two sets of USB estimates occur in urban areas where interactions with local NOx emissions can be important, especially when ozone levels are relatively low. Both methodologies conclude that seasonal mean daily 8-h maximum U.S. background ozone levels can be as high as 40-45 ppb over rural portions of the western U.S. Background fractions tend to decrease as modeled total ozone concentrations increase, with typical fractions of 75-100 percent on the lowest ozone days (<25 ppb) and typical fractions between 30 and 50% on days with ozone above 75 ppb. The finding that

  6. The ozone backlash

    SciTech Connect

    Taubes, G.

    1993-06-11

    While evidence for the role of chlorofluorocarbons in ozone depletion grows stronger, researchers have recently been subjected to vocal public criticism of their theories-and their motives. Their understanding of the mechanisms of ozone destruction-especially the annual ozone hole that appears in the Antarctic-has grown stronger, yet everywhere they go these days, they seem to be confronted by critics attacking their theories as baseless. For instance, Rush Limbaugh, the conservative political talk-show host and now-best-selling author of The Way Things Ought to Be, regularly insists that the theory of ozone depletion by CFCs is a hoax: bladerdash and poppycock. Zoologist Dixy Lee Ray, former governor of the state of Washington and former head of the Atomic Energy Commission, makes the same argument in her book, Trashing the Planet. The Wall Street Journal and National Review have run commentaries by S. Fred Singer, a former chief scientists for the Department of Transportation, purporting to shoot holes in the theory of ozone depletion. Even the June issue of Omni, a magazine with a circulation of more than 1 million that publishes a mixture of science and science fiction, printed a feature article claiming to expose ozone research as a politically motivated scam.

  7. Screening of Bangladeshi winter wheat (Triticum aestivum L.) cultivars for sensitivity to ozone.

    PubMed

    Saitanis, Costas J; Bari, Shafiqul M; Burkey, Kent O; Stamatelopoulos, Dimitris; Agathokleous, Evgenios

    2014-12-01

    The sensitivity to ozone of ten Bangladeshi wheat cultivars was tested by exposing plants to eight ozone exposure regimes (50, 60, 80, 100, 120, 135, 150, and 200 ppb for 14, 11, 8, 6, 5, 4, 3, and 1 days, respectively, for 8 h/day) in controlled environment chambers. Visible leaf injury, dry weight, chlorophyll, carotenoid content, leaf greenness (SPAD value), quantum yield of photosynthesis, and stomatal resistance were measured to evaluate response. Shoot biomass, total chlorophyll, leaf greenness, and carotenoid content were reduced in ozone-exposed plants. Based on the results of principal component analysis (PCA)-biplot analysis, the order of sensitivity to ozone was: Akbar > Sufi ≥ Bijoy ≥ Shatabdi > Bari-26 ≥ Gourab > Bari-25 ≥ Prodip ≥ Sourav > Kanchan. The most important parameters to discriminate cultivars with respect to ozone sensitivity were visible injury and chlorophyll b/a ratio, whereas quantum yield of photosynthesis was less important. Differences in stomatal resistance were not a significant factor in ozone response. Regression of cultivars' PCA scores against year of release revealed no trend, suggesting that ozone tolerance was not incorporated during cultivar breeding. PMID:25023654

  8. Long-term ozone and temperature correlations above SANAE, Antarctica

    NASA Technical Reports Server (NTRS)

    Bodeker, Gregory E.; Scourfield, Malcolm W. J.

    1994-01-01

    A significant decline in Antarctic total column ozone and upper air temperatures has been observed in recent years. Furthermore, high correlations between monthly mean values of ozone and stratospheric temperature have been measured above Syowa, Antarctica. For the observations reported here, data from TOMS (Total Ozone Mapping Spectrometer) aboard the Nimbus 7 satellite have been used to examine the 1980 to 1990 decrease in total column ozone above the South African Antarctic base of SANAE (70 deg 18 min S, 2 deg 21 min W). The cooling of the Antarctic stratosphere above SANAE during this period has been investigated by examining upper air temperatures at the 150, 100, 70, 50, and 30 hPa levels obtained from daily radiosonde balloon launches. Furthermore, these two data sets have been used to examine long-term, medium-term, and short-term correlations between total column ozone and the temperatures at each of the five levels. The trend in SANAE total column ozone has been found to be -4.9 DU/year, while upper air temperatures have been found to decrease at around 0.3 C/year. An analysis of monthly average SANAE total column ozone has shown the decrease to be most severe during the month of September with a trend of -7.7 DU/year. A strong correlation (r(exp 2) = 0.92) has been found between yearly average total column ozone and temperature at the 100 hPa level. Daily ozone and temperature correlations show high values from September to November, at a time when the polar vortex is breaking down.

  9. First-Principles Study of 8H-, 10H-, 12H-, and 18H-SiC Polytypes

    NASA Astrophysics Data System (ADS)

    Kobayashi, Kazuaki; Komatsu, Shojiro

    2012-02-01

    We calculated the electronic and lattice properties of 8H-, 10H-, 12H-, and 18H-SiC polytypes, which are sp3-bonded compounds. A tetrahedral structure is formed by Si and C atoms in their hexagonal polytypes. Their possible symmetries are P63mc and P3m1. All possible structures in the 8H polytype, six structures in the 10H polytype, seven structures in the 12H polytype, and one structure in the 18H polytype were considered. The calculated hexagonalities (H) are 16.7, 20, 25, 33.3, 40, 44.4, 50, 60, 66.7, 75, 80, and 83.3%. Hexagonality is a ratio of the number of hexagonal (h) characters and total number of cubic (c) and h characters in a unit cell. We calculated their electronic properties [i.e., electronic band structures, band gaps, valence band maximum (VBM), and conduction band minimum (CBM)]. All the calculated electronic band structures are nonmetallic and the band gaps are indirect. The lattice properties (i.e., lattice constants and internal coordinates of atoms in the unit cell) were optimized by the total energy pseudopotential method based on the local density approximation (LDA). There is no clear trend in the order of the total energies for the SiC polytype structures. The total energies of three 10H-SiC polytype structures are slightly lower than that of 4H-SiC. One of them, whose stacking sequence is ABCACBCACB (ABC notation) and whose H = 40%, is lower by 2.4 meV/Si2C2 than 4H-SiC, and lowest in the SiC polytype structures calculated by LDA. The Zhdanov notation of 10H-SiC(ABCACBCACB) is ``3322''. As for the 2H-, 3C-, 4H-, 6H-, 8H-, and 10H-SiC polytypes, we obtained their electronic and lattice properties using the total energy pseudopotential method based on the generalized gradient approximation (GGA) for comparison with the LDA results.

  10. Ozone in the Pacific Troposphere from Ozonesonde Observations

    NASA Technical Reports Server (NTRS)

    Oltmans, S. J.; Johnson, B. J.; Harris, J. M.; Voemel, H.; Koshy, K.; Simon, P.; Bendura, R.; Thompson, A. M.; Logan, J. A.; Hasebe, F.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Ozone vertical profile measurements obtained from ozonesondes flown at Fiji, Samoa, Tahiti and the Galapagos are used to characterize ozone in the troposphere over the tropical Pacific. There is a significant seasonal variation at each of these sites. At sites in both the eastern and western Pacific, ozone is highest at almost all levels in the troposphere during the September-November season and lowest during, March-May. There is a relative maximum at all of the sites in the mid-troposphere during all seasons of the year (the largest amounts are usually found near the tropopause). This maximum is particularly pronounced during, the September-November season. On average, throughout the troposphere at all seasons, the Galapagos has larger ozone amounts than the western Pacific sites. A trajectory climatology is used to identify the major flow regimes that are associated with the characteristic ozone behavior at various altitudes and seasons. The enhanced ozone seen in the mid-troposphere during September-November is associated with flow from the continents. In the western Pacific this flow is usually from southern Africa (although 10-day trajectories do not always reach the continent), but also may come from Australia and Indonesia. In the Galapagos the ozone peak in the mid-troposphere is seen in flow from the South American continent and particularly from northern Brazil. The time of year and flow characteristics associated with the ozone mixing ratio peaks seen in both the western and eastern Pacific suggest that these enhanced ozone values result from biomass burning. In the upper troposphere low ozone amounts are seen with flow that originates in the convective western Pacific.

  11. Tentative critical levels of tropospheric ozone for agricultural crops in Japan

    NASA Astrophysics Data System (ADS)

    Yonekura, T.

    2010-12-01

    Ground level ozone concentrations have increased year by year in Japan. High ozone concentrations have been known to affect growth and yield of agricultural crops. In the US and Europe, much effort has been directed to establish regulatory policies such as secondary air quality standard and critical levels to protect vegetation against ozone. On the contrary, in Japan, there is a few data of agricultural crops sensitivity to ozone. Furthermore, there is no information about the ozone risk of agricultural crop loss by based on ozone index (e.g. AOT40, SUM06, W126)-crop response relationship, yet. The objects of our research are: (1) to screen sensitivity of ozone on 10 crops cultivated in urban area in Japan. (2) to establish critical levels of ozone for protecting agricultural crops based on ozone index-crop response relationship. The 10 Japanese agricultural crops such as Japanese rice, Hanegi (Welsh onion), Shungiku (Crown daisy), Saradana (Lettus), Hatsukadaikon (Radish), Kokabu (Small Turnip), Santosai (Chinese cabbage), Tasai (Spinach mustard), Komatsuna (Japanese mustard spinach) and Chingensai (Bok Choy), were fumigated to three levels of ozone (clean air (< 5 ppbv), ambient level of ozone, 1.5 times ambient ozone) in open-top chambers during 30 to 120 days. Those experiments were repeated five times during two growing season. Throughout the experimental period, the growth or yield were measured, and the relationship between growth (or yield) and ozone index was examined. As a result, the influences of ozone on growth or yield were different among 10 crops. Relatively good correlations of coefficients of determination (r2) for linear regressions to growth or yield were obtained with “8h means” and “AOT40” rather than “SUM00”, “SUM06” and “W126”. Critical level for 10 crops in terms of an AOT40 were 1.1 to 2.1 ppm h per month. The ozone sensitive crop in our study was sound to be 1.0 ppm h per month in AOT40.

  12. Impact of Cabin Ozone Concentrations on Passenger Reported Symptoms in Commercial Aircraft

    PubMed Central

    Bekö, Gabriel; Allen, Joseph G.; Weschler, Charles J.; Vallarino, Jose; Spengler, John D.

    2015-01-01

    Due to elevated ozone concentrations at high altitudes, the adverse effect of ozone on air quality, human perception and health may be more pronounced in aircraft cabins. The association between ozone and passenger-reported symptoms has not been investigated under real conditions since smoking was banned on aircraft and ozone converters became more common. Indoor environmental parameters were measured at cruising altitude on 83 US domestic and international flights. Passengers completed a questionnaire about symptoms and satisfaction with the indoor air quality. Average ozone concentrations were relatively low (median: 9.5 ppb). On thirteen flights (16%) ozone levels exceeded 60 ppb, while the highest peak level reached 256 ppb for a single flight. The most commonly reported symptoms were dry mouth or lips (26%), dry eyes (22.1%) and nasal stuffiness (18.9%). 46% of passengers reported at least one symptom related to the eyes or mouth. A third of the passengers reported at least one upper respiratory symptom. Using multivariate logistic (individual symptoms) and linear (aggregated continuous symptom variables) regression, ozone was consistently associated with symptoms related to the eyes and certain upper respiratory endpoints. A concentration-response relationship was observed for nasal stuffiness and eye and upper respiratory symptom indicators. Average ozone levels, as opposed to peak concentrations, exhibited slightly weaker associations. Medium and long duration flights were significantly associated with more symptoms compared to short flights. The relationship between ultrafine particles and ozone on flights without meal service was indicative of ozone-initiated chemistry. PMID:26011001

  13. [Correlation Analysis Between Characteristics of VOCs and Ozone Formation Potential in Summer in Nanjing Urban District].

    PubMed

    Yang, Xiao-xiao; Tang, Li-li; Zhang, Yun-jiang; Mu, Ying-feng; Wang, Ming; Chen, Wen-tai; Zhou, Hong-cang; Hua, Yan; Jiang, Rong-xin

    2016-02-15

    Volatile organic compounds (VOCs) is an important precursor of photochemical ozone pollution (O3) in the atmosphere. Their concentration variation directly affects the characteristics of the ozone pollution. The concentration, speciation of VOCs, ozone and its precursors in Nanjing were analyzed and measured using online gas detection systems in August 2013. VOCs/NOx discriminant method was used to get the sensitive control factors of ozone. The results showed that the averaged volume fraction of VOCs was 52. 05 x 10(-9), and the largest one reached 200 x 10(-9) in Nanjing urban district. The order of volume fraction of each species VOCs was alkane > oxygen-containing VOCs > alkene > aromatics. The averaged concentration of ozone was 76.5 microg x m(-1) and the exceeding concentration of hourly standard was 5.9%. The change trends of ozone precursors VOCs and NOx were basically identical and Ozone showed the obvious negative correlation during the period of high concentrations of ozone. There were some differences in the concentrations of the same VOCs in different ozone concentration periods. The ozone generation in Nanjing urban district was sensitive to VOCs, and Nanjing belonged to VOCs control area in summer. PMID:27363129

  14. Changes in the Vertical Distribution of Ozone Over Canada From Ozonesondes: 1980-2001

    NASA Astrophysics Data System (ADS)

    Wardle, D. I.; Tarasick, D. W.; Fioletov, V. E.; Kerr, J. B.; Davies, J.

    2005-12-01

    Measurements of the vertical profile of ozone concentration using balloon-borne ECC ozonesondes have been made weekly since 1980 at several sites in Canada (Edmonton, Goose Bay, Churchill and Resolute), since 1987 at Alert and since 1992 at Eureka. Previous analyses of ozone trends over Canada have shown strong negative trends in tropospheric ozone. Here, with data up to the end of 2001, we find that while for the 1980-2001 period the overall linear trends are primarily negative, both in tropospheric and stratospheric ozone, when the data for 1991-2001 only are considered, the trends are positive, even in the lower stratosphere. When the time series are compared with previously reported trends (to 1993), it is evident that ozone has rebounded at all levels below about 63 hPa. These differences do not appear to be related to changes in tropopause height, as the average height of the tropopause (as measured over the ozonesonde stations) has not changed over either the 22-year or the 11-year period. Nevertheless, comparison with another dynamical indicator, the wintertime frequency of occurrence of laminae in the ozone profile, suggests that this rebound may be partly a result of small changes in the atmospheric circulation, rather than a recovery of the ozone layer from halocarbon-induced depletion. The long-term trends in average tropospheric ozone concentrations over Canada are similar to corresponding lower stratospheric trends, and tropospheric ozone levels show significant correlation with lower stratospheric ozone amounts.

  15. Impact of cabin ozone concentrations on passenger reported symptoms in commercial aircraft.

    PubMed

    Bekö, Gabriel; Allen, Joseph G; Weschler, Charles J; Vallarino, Jose; Spengler, John D

    2015-01-01

    Due to elevated ozone concentrations at high altitudes, the adverse effect of ozone on air quality, human perception and health may be more pronounced in aircraft cabins. The association between ozone and passenger-reported symptoms has not been investigated under real conditions since smoking was banned on aircraft and ozone converters became more common. Indoor environmental parameters were measured at cruising altitude on 83 US domestic and international flights. Passengers completed a questionnaire about symptoms and satisfaction with the indoor air quality. Average ozone concentrations were relatively low (median: 9.5 ppb). On thirteen flights (16%) ozone levels exceeded 60 ppb, while the highest peak level reached 256 ppb for a single flight. The most commonly reported symptoms were dry mouth or lips (26%), dry eyes (22.1%) and nasal stuffiness (18.9%). 46% of passengers reported at least one symptom related to the eyes or mouth. A third of the passengers reported at least one upper respiratory symptom. Using multivariate logistic (individual symptoms) and linear (aggregated continuous symptom variables) regression, ozone was consistently associated with symptoms related to the eyes and certain upper respiratory endpoints. A concentration-response relationship was observed for nasal stuffiness and eye and upper respiratory symptom indicators. Average ozone levels, as opposed to peak concentrations, exhibited slightly weaker associations. Medium and long duration flights were significantly associated with more symptoms compared to short flights. The relationship between ultrafine particles and ozone on flights without meal service was indicative of ozone-initiated chemistry. PMID:26011001

  16. Ozone-vegetation interaction in the Earth system: implications for air quality, ecosystems and agriculture

    NASA Astrophysics Data System (ADS)

    Tai, A. P. K.; Lombardozzi, D.; Val Martin, M.; Heald, C. L.

    2015-12-01

    Surface ozone is one of the most significant air pollutants due to its damaging effects not only on human health, but also on vegetation and crop productivity. Chronic ozone exposure has been shown to reduce photosynthesis and interfere with gas exchange in plants, which in turn affect the surface energy balance, carbon sink and other biogeochemical fluxes. Ozone damage on vegetation can thus have major ramifications on climate and atmospheric composition, including possible feedbacks onto ozone itself (see figure) that are not well understood. The damage of ozone on crops has been well documented, but a mechanistic understanding is not well established. Here we present several results pertaining to ozone-vegetation interaction. Using the Community Earth System Model, we find that inclusion of ozone damage on plants reduces the global land carbon sink by up to 5%, while simulated ozone is modified by -20 to +4 ppbv depending on the relative importance of competing mechanisms in different regions. We also perform a statistical analysis of multidecadal global datasets of crop yields, agroclimatic variables and ozone exposures to characterize the spatial variability of crop sensitivity to ozone and temperature extremes, specifically accounting for the confounding effect of ozone-temperature covariation. We find that several crops exhibit stronger sensitivity to ozone than found by previous field studies, with a strong anticorrelation between the sensitivity and average ozone levels that reflects biological adaptive ozone resistance. Our results show that a more complete understanding of ozone-vegetation interaction is necessary to derive more realistic future projections of climate, air quality and agricultural production, and thereby to formulate optimal strategies to safeguard public health and food security.

  17. Desorption of dimethylformamide from Zn4O(C8H4O4)3 framework

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Hu, Yun Hang

    2011-02-01

    Both dimethylformamide (DMF) and diethylformamide (DEF) are important solvents for the synthesis of Zn4O(C8H4O4)3 framework (MOF-5). It is generally recognized that DMF molecules can be completely displaced by CH2Cl2 during the synthesis of MOF-5. Herein, however, it was found that the DMF molecules inside the pores of the MOF-5 framework cannot be displaced by CH2Cl2. The desorption of the DMF molecules from the pores, which requires a temperature of 100 °C or above, is the first order with activation energy of 56.38 kJ/mol. In contrast, DEF molecules can be completely displaced by CH2Cl2 during the synthesis of MOF-5, because DEF molecules cannot penetrate into the pores of the MOF-5 paste.

  18. Tropospheric ozone and ozone profiles retrieved from GOME-2 and their validation

    NASA Astrophysics Data System (ADS)

    Miles, G. M.; Siddans, R.; Kerridge, B. J.; Latter, B. G.; Richards, N. A. D.

    2015-01-01

    This paper describes and assesses the performance of the RAL (Rutherford Appleton Laboratory) ozone profile retrieval scheme for the Global Ozone Monitoring Experiment 2 (GOME-2) with a focus on tropospheric ozone. Developments to the scheme since its application to GOME-1 measurements are outlined. These include the approaches developed to account sufficiently for UV radiometric degradation in the Hartley band and for inadequacies in knowledge of instrumental parameters in the Huggins bands to achieve the high-precision spectral fit required to extract information on tropospheric ozone. The assessment includes a validation against ozonesondes (sondes) sampled worldwide over 2 years (2007-2008). Standard deviations of the ensemble with respect to the sondes are considerably lower for the retrieved profiles than for the a priori, with the exception of the lowest subcolumn. Once retrieval vertical smoothing (averaging kernels) has been applied to the sonde profiles there is a retrieval bias of 6% (1.5 DU) in the lower troposphere, with smaller biases in the subcolumns above. The bias in the troposphere varies with latitude. The retrieval underestimates lower tropospheric ozone in the Southern Hemisphere (SH) (15-20% or ~ 1-3 DU) and overestimates it in the Northern Hemisphere (NH) (10% or 2 DU). The ability of the retrieval to reflect the geographical distribution of lower tropospheric ozone, globally (rather than just ozonesonde launch sites) is demonstrated by comparison with the chemistry transport model TOMCAT. For a monthly mean of cloud-cleared GOME-2 pixels, a correlation of 0.66 is found between the retrieval and TOMCAT sampled accordingly, with a bias of 0.7 Dobson Units. GOME-2 estimates higher concentrations in NH pollution centres but lower ozone in the Southern Ocean and South Pacific, which is consistent with the comparison to ozonesondes.

  19. Assessment of transboundary ozone contribution toward South Korea using multiple source-receptor modeling techniques

    NASA Astrophysics Data System (ADS)

    Choi, Ki-Chul; Lee, Jong-Jae; Bae, Chang Han; Kim, Cheol-Hee; Kim, Soontae; Chang, Lim-Seok; Ban, Soo-Jin; Lee, Suk-Jo; Kim, Jongchoon; Woo, Jung-Hun

    2014-08-01

    Ozone concentrations in East Asia were simulated using the Community Multi-scale Air Quality (CMAQ) model, and its source contributions were estimated by multiple source-receptor modeling techniques. To study relationships between ozone concentrations and precursor emission sources, three approaches were applied to four months (January, April, July, and October 2009) to represent seasonal characteristics and compare results, with a particular focus on South Korea. Brute force (BF) is a traditional sensitivity analysis method used to estimate model output response to an input change. The high-order decoupled direct method (HDDM), a computational method, is an efficient and accurate alternative to the BF method for sensitivity. The Ozone and Particulate Precursor Tagging Methodology (OPTM) provides contribution information quantified by tracking emissions from selected sources throughout the simulation period. The approaches generally show that most of the receptor regions were substantially influenced by emissions from central China, which is the largest anthropogenic emissions source region in East Asia. Local emissions were still major contributors, especially South Korea and Japan during July 2009. On the other hand, a case study of maximum 8-h ozone concentrations derived from CMAQ-OPTM on April 9 in South Korea shows that the NOx and VOCs emissions from China contributed approximately 82% and 91%, respectively, to maximum 8-h ozone in Region 4 (South Korea) without boundary inflow, which indicates that Chinese emissions are the dominant contributor in this episode. A comparison study of the three approaches shows that HDDM tends to estimate biogenic source contributions lower than that from OPTM in China but similar to OPTM in South Korea and Japan. When comparing the BF method and HDDM, the sensitivity results show a reasonably good agreement during a given period. The location- and time-dependent maximum 8-h ozone isopleths over South Korea as a receptor

  20. MULTIPOLLUTANT METHODS - METHODS FOR OZONE AND OZONE PRECURSORS

    EPA Science Inventory

    This task involves the development and testing of methods for monitoring ozone and compounds associated with the atmospheric chemistry of ozone production both as precursors and reaction products. Although atmospheric gases are the primary interest, separation of gas and particl...

  1. An evaluation of ozone exposure metrics for a seasonally drought-stressed ponderosa pine ecosystem.

    PubMed

    Panek, Jeanne A; Kurpius, Meredith R; Goldstein, Allen H

    2002-01-01

    Ozone stress has become an increasingly significant factor in cases of forest decline reported throughout the world. Current metrics to estimate ozone exposure for forest trees are derived from atmospheric concentrations and assume that the forest is physiologically active at all times of the growing season. This may be inaccurate in regions with a Mediterranean climate, such as California and the Pacific Northwest, where peak physiological activity occurs early in the season to take advantage of high soil moisture and does not correspond to peak ozone concentrations. It may also misrepresent ecosystems experiencing non-average climate conditions such as drought years. We compared direct measurements of ozone flux into a ponderosa pine canopy with a suite of the most common ozone exposure metrics to determine which best correlated with actual ozone uptake by the forest. Of the metrics we assessed, SUM0 (the sum of all daytime ozone concentrations > 0) best corresponded to ozone uptake by ponderosa pine, however the correlation was only strong at times when the stomata were unconstrained by site moisture conditions. In the early growing season (May and June). SUM0 was an adequate metric for forest ozone exposure. Later in the season, when stomatal conductance was limited by drought. SUM0 overestimated ozone uptake. A better metric for seasonally drought-stressed forests would be one that incorporates forest physiological activity, either through mechanistic modeling, by weighting ozone concentrations by stomatal conductance, or by weighting concentrations by site moisture conditions. PMID:11843543

  2. What would have happened to the ozone layer if chlorofluorocarbons (CFCs) had not been regulated?

    NASA Astrophysics Data System (ADS)

    Newman, P. A.; Oman, L. D.; Douglass, A. R.; Fleming, E. L.; Frith, S. M.; Hurwitz, M. M.; Kawa, S. R.; Jackman, C. H.; Krotkov, N. A.; Nash, E. R.; Nielsen, J. E.; Pawson, S.; Stolarski, R. S.; Velders, G. J. M.

    2009-03-01

    Ozone depletion by chlorofluorocarbons (CFCs) was first proposed by Molina and Rowland in their 1974 Nature paper. Since that time, the scientific connection between ozone losses and CFCs and other ozone depleting substances (ODSs) has been firmly established with laboratory measurements, atmospheric observations, and modeling studies. This science research led to the implementation of international agreements that largely stopped the production of ODSs. In this study we use a fully-coupled radiation-chemical-dynamical model to simulate a future world where ODSs were never regulated and ODS production grew at an annual rate of 3%. In this "world avoided" simulation, 17% of the globally-averaged column ozone is destroyed by 2020, and 67% is destroyed by 2065 in comparison to 1980. Large ozone depletions in the polar region become year-round rather than just seasonal as is currently observed in the Antarctic ozone hole. Very large temperature decreases are observed in response to circulation changes and decreased shortwave radiation absorption by ozone. Ozone levels in the tropical lower stratosphere remain constant until about 2053 and then collapse to near zero by 2058 as a result of heterogeneous chemical processes (as currently observed in the Antarctic ozone hole). The tropical cooling that triggers the ozone collapse is caused by an increase of the tropical upwelling. In response to ozone changes, ultraviolet radiation increases, more than doubling the erythemal radiation in the northern summer midlatitudes by 2060.

  3. What would have happened to the ozone layer if chlorofluorocarbons (CFCs) had not been regulated?

    NASA Astrophysics Data System (ADS)

    Newman, P. A.; Oman, L. D.; Douglass, A. R.; Fleming, E. L.; Frith, S. M.; Hurwitz, M. M.; Kawa, S. R.; Jackman, C. H.; Krotkov, N. A.; Nash, E. R.; Nielsen, J. E.; Pawson, S.; Stolarski, R. S.; Velders, G. J. M.

    2008-12-01

    Ozone depletion by chlorofluorocarbons (CFCs) was first proposed by Molina and Rowland in their 1974 Nature paper. Since that time, the scientific connection between ozone losses and CFCs and other ozone depleting substances (ODSs) has been firmly established with laboratory measurements, atmospheric observations, and modeling research. This science research led to the implementation of international agreements that largely stopped the production of ODSs. In this study we use a fully-coupled radiation-chemical-dynamical model to simulate a future world where ODSs were never regulated and ODS production grew at an annual rate of 3%. In this "world avoided" simulation, 17% of the globally-average column ozone is destroyed by 2020, and 67% is destroyed by 2065 in comparison to 1980. Large ozone depletions in the polar region become year-round rather than just seasonal as is currently observed in the Antarctic ozone hole. Very large temperature decreases are observed in response to circulation changes and decreased shortwave radiation absorption by ozone. Ozone levels in the tropical lower stratosphere remain constant until about 2053 and then collapse to near zero by 2058 as a result of heterogeneous chemical processes (as currently observed in the Antarctic ozone hole). The tropical cooling that triggers the ozone collapse is caused by an increase of the tropical upwelling. In response to ozone changes, ultraviolet radiation increases, more than doubling the erythemal radiation in the northern summer midlatitudes by 2060.

  4. What would have happened to the ozone layer if chlorofluorocarbons (CFCs) had not been regulated?

    NASA Astrophysics Data System (ADS)

    Newman, P. A.; Oman, L. D.; Douglass, A. R.; Fleming, E. L.; Frith, S. M.; Hurwitz, M. M.; Kawa, S. R.; Jackman, C. H.; Krotkov, N. A.; Nash, E. R.; Nielsen, J. E.; Pawson, S.; Stolarski, R. S.; Velders, G. J.

    2008-12-01

    Ozone depletion by chlorofluorocarbons (CFCs) was first proposed by Molina and Rowland in their 1974 Nature paper. Since that time, the scientific connection between ozone losses and CFCs and other ozone depleting substances (ODSs) has been firmly established with laboratory measurements, atmospheric observations, and modeling research. The nations of the world implemented the Montreal Protocol (and amendments) which stopped ODS production in 1992. In this presentation we use a fully coupled radiation- chemical-dynamical model to simulate a future world where ODSs were never regulated and ODS production grew at an annual rate of 3%. In this "world avoided" simulation, 17% of the globally average column ozone is destroyed by 2020, and 67% is destroyed by 2065 in comparison to 1980. Large ozone depletions in the polar region become year-round rather than just seasonal as is currently observed in the Antarctic ozone hole. Very large temperature decreases are observed in response to circulation changes and decreased shortwave radiation absorption by ozone. Ozone levels in the tropical lower stratosphere remain constant until about 2053 and then collapse to near zero by 2058 as a result of heterogeneous chemical processes (as currently observed in the Antarctic ozone hole). The tropical cooling that triggers the ozone collapse is caused by an increase of the tropical upwelling. In response to ozone changes, ultraviolet (UV) radiation increases, tripling the erythemal (sunburn) radiation in the northern summer mid-latitudes by 2065.

  5. What Would Have Happened to the Ozone Layer if Chlorofluorocarbons (CFCs) had not been Regulated?

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.; Oman, L. D.; Douglass, A. R.; Fleming, E. L.; Frith, S. M.; Hurwitz, M. M.; Kawa, S. R.; Jackman, C. H.; Krotkov, N. A.; Nash, E. R.; Nielsen, J. E.; Pawson, S.; Stolarski, R. S.; Velders, G. J. M.

    2008-01-01

    Ozone depletion by chlorofluorocarbons (CFCs) was first proposed by Molina and Rowland in their 1974 Nature paper. Since that time, the sci entific connection between ozone losses and CFCs and other ozone depl eting substances (ODSs) has been firmly established with laboratory m easurements, atmospheric observations, and modeling research. This science research led to the implementation of international agreements t hat largely stopped the production of ODSs. In this study we use a fu lly-coupled radiation-chemical-dynamical model to simulate a future world where ODSs were never regulated and ODS production grew at an ann ual rate of 3%. In this "world avoided" simulation 1.7 % of the globa lly-average column ozone is destroyed by 2020, and 67% is destroyed b y 2065 in comparison to 1980. Large ozone depletions in the polar region become year-round rather than just seasonal as is currently observ ed in the Antarctic ozone hole. Very large temperature decreases are observed in response to circulation changes and decreased shortwave radiation absorption by ozone. Ozone levels in the tropical lower strat osphere remain constant until about 2053 and then collapse to near ze ro by 2058 as a result of heterogeneous chemical processes (as curren tly observed in the Antarctic ozone hole). The tropical cooling that triggers the ozone collapse is caused by an increase of the tropical upwelling. In response to ozone changes, ultraviolet radiation increa ses, more than doubling the erythemal radiation in the northern summer midlatitudes by 2060.

  6. Ozone Depletion by Hydrofluorocarbons

    NASA Astrophysics Data System (ADS)

    Hurwitz, M.; Fleming, E. L.; Newman, P. A.; Li, F.; Mlawer, E. J.; Cady-Pereira, K. E.; Bailey, R.

    2015-12-01

    Hydrofluorocarbons (HFCs) are second-generation replacements for the chlorofluorocarbons (CFCs), halons and other substances that caused the 'ozone hole'. Atmospheric concentrations of HFCs are projected to increase dramatically in the coming decades. Coupled chemistry-climate simulations forced by these projections show that HFCs will impact the global atmosphere in 2050. As strong radiative forcers, HFCs modulate atmospheric temperature, thereby changing ozone-destroying catalytic cycles and enhancing the stratospheric circulation. These changes lead to a weak depletion of stratospheric ozone. Sensitivity simulations with the NASA Goddard Space Flight Center (GSFC) 2D model show that HFC-125 is the most important contributor to atmospheric change in 2050, as compared with HFC-23, HFC-32, HFC-134a and HFC-143a. Incorporating the interactions between chemistry, radiation and dynamics, for a likely 2050 climate, ozone depletion potentials (ODPs) for HFCs range from 4.3x10-4 to 3.5x10-2; previously HFCs were assumed to have negligible ODPs since these species lack chlorine or bromine atoms. The ozone impacts of HFCs are further investigated with the Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM). The GEOSCCM is a three-dimensional, fully coupled ocean-atmosphere model with interactive stratospheric chemistry. Sensitivity simulations in which CO2, CFC-11 and HCFC-22 are enhanced individually are used as proxies for the atmospheric response to the HFC concentrations expected by the mid-21st century. Sensitivity simulations provide quantitative estimates of the impacts of these greenhouse gases on global total ozone, and can be used to assess their effects on the recovery of Antarctic ozone.

  7. Ozone-induced airway epithelial cell death, the neurokinin-1 receptor pathway, and the postnatal developing lung

    PubMed Central

    Murphy, Shannon R.; Oslund, Karen L.; Hyde, Dallas M.; Miller, Lisa A.; Van Winkle, Laura S.

    2014-01-01

    Children are uniquely susceptible to ozone because airway and lung growth continue for an extensive period after birth. Early-life exposure of the rhesus monkey to repeated ozone cycles results in region-specific disrupted airway/lung growth, but the mediators and mechanisms are poorly understood. Substance P (SP), neurokinin-1 receptor (NK-1R); and nuclear receptor Nur77 (NR4A1) are signaling pathway components involved in ozone-induced cell death. We hypothesize that acute ozone (AO) exposure during postnatal airway development disrupts SP/NK-1R/Nur77 pathway expression and that these changes correlate with increased ozone-induced cell death. Our objectives were to 1) spatially define the normal development of the SP/NK-1R/Nur77 pathway in conducting airways; 2) compare how postnatal age modulates responses to AO exposure; and 3) determine how concomitant, episodic ozone exposure modifies age-specific acute responses. Male infant rhesus monkeys were assigned at age 1 mo to two age groups, 2 or 6 mo, and then to one of three exposure subgroups: filtered air (FA), FA+AO (AO: 8 h/day × 2 days), or episodic biweekly ozone exposure cycles (EAO: 8 h/day × 5 days/14-day cycle+AO). O3 = 0.5 ppm. We found that 1) ozone increases SP/NK-1R/Nur77 pathway expression in conducting airways, 2) an ozone exposure cycle (5 days/cycle) delivered early at age 2 mo resulted in an airway that was hypersensitive to AO exposure at the end of 2 mo, and 3) continued episodic exposure (11 cycles) resulted in an airway that was hyposensitive to AO exposure at 6 mo. These observations collectively associate with greater overall inflammation and epithelial cell death, particularly in early postnatal (2 mo), distal airways. PMID:25063800

  8. Short-Term Exposure to Ozone Does Not Impair Vascular Function or Affect Heart Rate Variability in Healthy Young Men

    PubMed Central

    Barath, Stefan; Langrish, Jeremy P.; Blomberg, Anders

    2013-01-01

    Air pollution exposure is associated with cardiovascular morbidity and mortality, yet the role of individual pollutants remains unclear. In particular, there is uncertainty regarding the acute effect of ozone exposure on cardiovascular disease. In these studies, we aimed to determine the effect of ozone exposure on vascular function, fibrinolysis, and the autonomic regulation of the heart. Thirty-six healthy men were exposed to ozone (300 ppb) and filtered air for 75min on two occasions in randomized double-blind crossover studies. Bilateral forearm blood flow (FBF) was measured using forearm venous occlusion plethysmography before and during intra-arterial infusions of vasodilators 2–4 and 6–8h after each exposure. Heart rhythm and heart rate variability (HRV) were monitored during and 24h after exposure. Compared with filtered air, ozone exposure did not alter heart rate, blood pressure, or resting FBF at either 2 or 6h. There was a dose-dependent increase in FBF with all vasodilators that was similar after both exposures at 2–4h. Ozone exposure did not impair vasomotor or fibrinolytic function at 6–8h but rather increased vasodilatation to acetylcholine (p = .015) and sodium nitroprusside (p = .005). Ozone did not affect measures of HRV during or after the exposure. Our findings do not support a direct rapid effect of ozone on vascular function or cardiac autonomic control although we cannot exclude an effect of chronic exposure or an interaction between ozone and alternative air pollutants that may be responsible for the adverse cardiovascular health effects attributed to ozone. PMID:23872581

  9. Americans' Average Radiation Exposure

    SciTech Connect

    NA

    2000-08-11

    We live with radiation every day. We receive radiation exposures from cosmic rays, from outer space, from radon gas, and from other naturally radioactive elements in the earth. This is called natural background radiation. It includes the radiation we get from plants, animals, and from our own bodies. We also are exposed to man-made sources of radiation, including medical and dental treatments, television sets and emission from coal-fired power plants. Generally, radiation exposures from man-made sources are only a fraction of those received from natural sources. One exception is high exposures used by doctors to treat cancer patients. Each year in the United States, the average dose to people from natural and man-made radiation sources is about 360 millirem. A millirem is an extremely tiny amount of energy absorbed by tissues in the body.

  10. Spatio-temporal modeling for real-time ozone forecasting

    PubMed Central

    Paci, Lucia; Gelfand, Alan E.; Holland, David M.

    2013-01-01

    The accurate assessment of exposure to ambient ozone concentrations is important for informing the public and pollution monitoring agencies about ozone levels that may lead to adverse health effects. High-resolution air quality information can offer significant health benefits by leading to improved environmental decisions. A practical challenge facing the U.S. Environmental Protection Agency (USEPA) is to provide real-time forecasting of current 8-hour average ozone exposure over the entire conterminous United States. Such real-time forecasting is now provided as spatial forecast maps of current 8-hour average ozone defined as the average of the previous four hours, current hour, and predictions for the next three hours. Current 8-hour average patterns are updated hourly throughout the day on the EPA-AIRNow web site. The contribution here is to show how we can substantially improve upon current real-time forecasting systems. To enable such forecasting, we introduce a downscaler fusion model based on first differences of real-time monitoring data and numerical model output. The model has a flexible coefficient structure and uses an efficient computational strategy to fit model parameters. Our hybrid computational strategy blends continuous background updated model fitting with real-time predictions. Model validation analyses show that we are achieving very accurate and precise ozone forecasts. PMID:24010052

  11. Changes in US background ozone due to global anthropogenic emissions from 1970 to 2020

    NASA Astrophysics Data System (ADS)

    Nopmongcol, Uarporn; Jung, Jaegun; Kumar, Naresh; Yarwood, Greg

    2016-09-01

    Estimates of North American and US Background (NAB and USB) ozone (O3) are critical in setting and implementing the US National Ambient Air Quality Standards (NAAQS) and therefore influence population exposure to O3 across the US. NAB is defined as the O3 concentration in the absence of anthropogenic O3 precursor emissions from North America whereas USB excludes anthropogenic emissions inside the US alone. NAB and USB vary geographically and with time of year. Analyses of O3 trends at rural locations near the west coast suggest that background O3 is rising in response to increasing non-US emissions. As the O3 NAAQS is lowered, rising background O3 would make attaining the NAAQS more difficult. Most studies of changing US background O3 have inferred trends from observations whereas air quality management decisions tend to rely on models. Thus, it is important that the models used to develop O3 management strategies are able to represent the changes in background O3 in order to increase confidence that air quality management strategies will succeed. We focus on how changing global emissions influence USB rather than the effects of inter-annual meteorological variation or long-term climate change. We use a regional model (CAMx) nested within a global model (GEOS-Chem) to refine our grid resolution over high terrain in the western US and near US borders where USB tends to be higher. We determine USB from CAMx simulations that exclude US anthropogenic emissions. Over five decades, from 1970 to 2020, estimated USB for the annual fourth highest maximum daily 8-h average O3 (H4MDA8) in the western US increased from mostly in the range of 40-55 ppb to 45-60 ppb, but remained below 45 ppb in the eastern US. USB increases in the southwestern US are consistent with rising emissions in Asia and Mexico. USB decreases in the northeast US after 1990 follow declining Canadian emissions. Our results show that the USB increases both for the top 30 MDA8 days and the H4MDA8 (the former

  12. Detecting the Recovery of the Antarctic Ozone Hole

    NASA Technical Reports Server (NTRS)

    Newman, Paul A.; Nash, Eric R.; Kawa, S. Randolph; Montzka, Steve

    2004-01-01

    The Antarctic ozone hole develops each year and culminates by early Spring. Antarctic ozone values have been monitored since 1979 using satellite observations from the TOMS instrument. The severity of the hole has been assessed from TOMS using the minimum total ozone value from the October monthly mean (depth of the hole) and by calculating the average size during the September-October period. Ozone is mainly destroyed by halogen catalytic cycles, and these losses are modulated by temperature variations in the collar of the polar lower stratospheric vortex. In this presentation, we show the relationships of halogens and temperature to both the size and depth of the hole. Because atmospheric halogen levels are responding to international agreements that limit or phase out production, the amount of halogens in the stratosphere should decrease over the next few decades. Using projections of halogen levels combined with age-of-air estimates, we find that the ozone hole is recovering at an extremely slow rate and that large ozone holes will regularly recur over the next 2 decades. We will show estimates of both when the ozone hole will begin to show first signs of recovery, and when the hole will fully recover to pre-1980 levels.

  13. Perspectives on African Ozone from Sondes, Dobson and Aircraft Measurements

    NASA Technical Reports Server (NTRS)

    Thompson, A. M.; Witte, J. C.; Chatfield, R. B.; Diab, R. D.; Thouret, V.; Sauvage, B.

    2004-01-01

    We have been studying variability in ozone over Africa using data from ozonesondes (vertical profiles from surface to stratosphere), aircraft (the MOZAIC dataset with cruise altitude and landing/takeoff profiles) and the ground (Dobson spectrophotometer total ozone column measurement). The following may give context for ozone investigations during AMMA: 1. Total ozone measurements since 1989 show considerable variability in mean value among the African stations in Algeria, Kenya, Egypt, South Africa, as well as in seasonal cycles and year-to-year. Trends are not evident. 2. The impacts of convection, stratospheric injection, biomass burning and lightning appear in ozone sounding profile data. Time-series analysis and case studies point to periodic influences of long-range interactions with the Atlantic ("ozone paradox," wave-one") and Indian Oceans. 3. Tropospheric ozone variations, observed in tropospheric profiles and integrated column amount, follow general seasonal patterns but short- term variability is so strong that simple averages are inadequate for describing "climatology" and statistical classification approaches may be required.

  14. Synoptic and meteorological drivers of extreme ozone concentrations over Europe

    NASA Astrophysics Data System (ADS)

    Otero, Noelia Felipe; Sillmann, Jana; Schnell, Jordan L.; Rust, Henning W.; Butler, Tim

    2016-04-01

    The present work assesses the relationship between local and synoptic meteorological conditions and surface ozone concentration over Europe in spring and summer months, during the period 1998-2012 using a new interpolated data set of observed surface ozone concentrations over the European domain. Along with local meteorological conditions, the influence of large-scale atmospheric circulation on surface ozone is addressed through a set of airflow indices computed with a novel implementation of a grid-by-grid weather type classification across Europe. Drivers of surface ozone over the full distribution of maximum daily 8-hour average values are investigated, along with drivers of the extreme high percentiles and exceedances or air quality guideline thresholds. Three different regression techniques are applied: multiple linear regression to assess the drivers of maximum daily ozone, logistic regression to assess the probability of threshold exceedances and quantile regression to estimate the meteorological influence on extreme values, as represented by the 95th percentile. The relative importance of the input parameters (predictors) is assessed by a backward stepwise regression procedure that allows the identification of the most important predictors in each model. Spatial patterns of model performance exhibit distinct variations between regions. The inclusion of the ozone persistence is particularly relevant over Southern Europe. In general, the best model performance is found over Central Europe, where the maximum temperature plays an important role as a driver of maximum daily ozone as well as its extreme values, especially during warmer months.

  15. Tropospheric ozone climatology over Peninsular Malaysia from 1992 to 1999

    NASA Astrophysics Data System (ADS)

    Yonemura, Seiichiro; Tsuruta, Haruo; Kawashima, Shigeto; Sudo, Shigeto; Peng, Leong Chow; Fook, Lim Sze; Johar, Zubaidi; Hayashi, Masayasu

    2002-08-01

    We present the climatology of tropospheric ozone over Peninsular Malaysia in tropical Asia for the 8 years from 1992 through 1999 as measured by ozonesondes twice a month. The mean ozone concentrations in vertical profile were in the same range (30-40 ppbv) as those observed at Watukosek, Indonesia, and were lower than those at Natal, Brazil, South America, and at Brazzaville, Congo, Africa, indicating that air masses over Peninsular Malaysia are primarily influenced by the maritime environment and deep convection, as shown by the significant levels of water vapor in the middle troposphere throughout the year. Seasonally averaged ozone concentrations were highest in December, January, and February (DJF) from 6 to 7.5 km altitude and in March, April, and May (MAM) at all other heights and were lowest in June, July, and August (JJA) and September, October, and November (SON), excluding 1994 and 1997, at all heights. The ozone enhancements during DJF in the middle troposphere could be caused by depression of the deep convection because of the positive temperature anomaly and negative water vapor anomaly. The ozone enhancements above the middle troposphere (>5 km) in MAM, especially in 1997 and 1998, could be predominantly attributed to photochemical production from enhanced ozone precursor gases of Northern Hemisphere origin, especially biomass burning in continental Southeast Asia. Large ozone enhancements as high as 10-20 Dobson units observed during SON of 1994 and 1997 were associated with large-scale biomass burnings in Indonesia.

  16. Ozone Contamination in Aircraft Cabins. Appendix A: Ozone toxicity

    NASA Technical Reports Server (NTRS)

    Melton, C. E.

    1979-01-01

    The recommendation that at various altitudes the amount of air with which ozone has mixed changes, thus changing the volume per volume relationship is discussed. The biological effects of ozone on human health and the amount of ozone necessary to produce symptoms were investigated.

  17. Children's Models of the Ozone Layer and Ozone Depletion.

    ERIC Educational Resources Information Center

    Christidou, Vasilia; Koulaidis, Vasilis

    1996-01-01

    The views of 40 primary students on ozone and its depletion were recorded through individual, semi-structured interviews. The data analysis resulted in the formation of a limited number of models concerning the distribution and role of ozone in the atmosphere, the depletion process, and the consequences of ozone depletion. Identifies five target…

  18. CONTRIBUTION TO INDOOR OZONE LEVELS OF AN OZONE GENERATOR

    EPA Science Inventory

    This report gives results of a study of a commonly used commercially available ozone generator, undertaken to determine its impact on indoor ozone levels. xperiment were conducted in a typical mechanically ventilated office and in a test house. he generated ozone and the in-room ...

  19. Ozone Minimums, 1979 to 2013

    NASA Video Gallery

    Minimum concentration of ozone in the southern hemisphere for each year from 1979-2013 (there is no data from 1995). Each image is the day of the year with the lowest concentration of ozone. A grap...

  20. "OZONE SOURCE APPORTIONMENT IN CMAQ'

    EPA Science Inventory

    Ozone source attribution has been used to support various policy purposes including interstate transport (Cross State Air Pollution Rule) by U.S. EPA and ozone nonattainment area designations by State agencies. Common scientific applications include tracking intercontinental tran...

  1. An automated ozone photometer

    NASA Technical Reports Server (NTRS)

    Lavelle, Joseph R.

    1988-01-01

    A photometer capable of automatically measuring ozone concentration data to very high resolution during scientific research flights in the Earth's atmosphere was developed at NASA Ames Research Center. This instrument was recently deployed to study the ozone hole over Antarctica. Ozone is detected by absorbing 253.7-nm radiation from an ultraviolet lamp which shines through the sample of air and impinges on a vacuum phototube. A lower output from the phototube indicates more ozone present in the air sample. The photometer employs a CMOS Z80 microprocessor with an STD bus system for experiment control, data collection, and storage. Data are collected and stored in nonvolatile memory for experiments lasting up to 8 hr. Data are downloaded to a portable ground-support computer and processed after the aircraft lands. An independent single-board computer in the STD bus also calculates ozone concentration in real time with less resolution than the CMOS Z80 system, and sends this value to a cockpit meter to aid the pilot in navigation.

  2. Stratospheric Ozone Predictions For The Late 21st Century

    NASA Astrophysics Data System (ADS)

    Douglass, A. R.; Olsen, M. A.; Stolarski, R. S.; Strahan, S. E.; Oman, L.

    2013-12-01

    Simulations of ozone evolution from 1960 until ~2100 from chemistry climate models (CCMs) that participated in CCMVal-2 are broadly consistent in that stratospheric ozone increases as chlorofluorcarbons decrease and the stratosphere cools (which affects the rate of temperature dependent loss processes), however, details of the projections vary significantly. Differences in the ozone response to specified changes in chlorine containing source gases dominate during the first half of the integrations. For example, from 1980 to 2000, chlorine change is by far the most important cause of ozone change, and the CCMs produce changes in the 60S-60N average column ozone that range between -3 DU and -17 DU. In the second half of the 21st century climate change is primarily responsible for ozone change. By 2080 the CCMs produce changes in the 60S-60N average upper stratospheric ozone column that range from 4 DU to 10 DU. The CCM range of differences is due to differences in both composition and upper stratospheric temperature. Ozone loss processes each have their own temperature sensitivity, and the net sensitivity of ozone to temperature change in each CCM depends on the relative importance of each loss process; this depends on the composition and temperature for the baseline atmosphere. In the lower stratosphere, climate change affects ozone evolution through changes in photochemical reaction rates due to stratospheric cooling and through circulation differences affecting transport of ozone and other trace gases. These are not separable using an approach such as multiple linear regression because changes in circulation and temperature have the same time dependence after accounting for contributions due to chlorine change. Recent attention has focused on similarity of the CCMs in that all predict a speed-up of the Brewer Dobson circulation. However, differences in the magnitude of the speed-up, differences in horizontal mixing and differences in the photochemical response to

  3. Developing a predictive tropospheric ozone model for Tabriz

    NASA Astrophysics Data System (ADS)

    Khatibi, Rahman; Naghipour, Leila; Ghorbani, Mohammad A.; Smith, Michael S.; Karimi, Vahid; Farhoudi, Reza; Delafrouz, Hadi; Arvanaghi, Hadi

    2013-04-01

    Predictive ozone models are becoming indispensable tools by providing a capability for pollution alerts to serve people who are vulnerable to the risks. We have developed a tropospheric ozone prediction capability for Tabriz, Iran, by using the following five modeling strategies: three regression-type methods: Multiple Linear Regression (MLR), Artificial Neural Networks (ANNs), and Gene Expression Programming (GEP); and two auto-regression-type models: Nonlinear Local Prediction (NLP) to implement chaos theory and Auto-Regressive Integrated Moving Average (ARIMA) models. The regression-type modeling strategies explain the data in terms of: temperature, solar radiation, dew point temperature, and wind speed, by regressing present ozone values to their past values. The ozone time series are available at various time intervals, including hourly intervals, from August 2010 to March 2011. The results for MLR, ANN and GEP models are not overly good but those produced by NLP and ARIMA are promising for the establishing a forecasting capability.

  4. Approach to forecasting daily maximum ozone levels in St. Louis

    NASA Technical Reports Server (NTRS)

    Prior, E. J.; Schiess, J. R.; Mcdougal, D. S.

    1981-01-01

    Measurements taken in 1976 from the St. Louis Regional Air Pollution Study (RAPS) data base, conducted by EPA, were analyzed to determine an optimum set of air-quality and meteorological variables for predicting maximum ozone levels for each day in 1976. A 'leaps and bounds' regression analysis was used to identify the best subset of variables. Three particular variables, the 9 a.m. ozone level, the forecasted maximum temperature, and the 6-9 a.m. averaged wind speed, have useful forecasting utility. The trajectory history of air masses entering St. Louis was studied, and it was concluded that transport-related variables contribute to the appearance of very high ozone levels. The final empirical forecast model predicts the daily maximum ozone over 341 days with a standard deviation of 11 ppb, which approaches the estimated error.

  5. Winter rain and summer ozone: a predictive relationship.

    PubMed

    Sandberg, J S; Basso, M J; Okin, B A

    1978-06-01

    Insights from dendrochronology have provided a new seasonal predictor for air pollution meteorology. In the San Francisco Bay Area summer ozone excesses over the federal ozone standard are correlated (correlation coefficient r = .87) with precipitation for the two preceding winters, a factor related to tree-ring width in a precipitation-stressed climate. The hypothesis that reactive hydrocarbon emissions from vegetative biomass affects these ozone excesses was supported by a similar correlation between summer hydrocarbon average maximums and the two-winter precipitation factor, reaching r = .88 at suburban stations. A weak tendency for hot summers to follow wet winters (in 16 years of California data) explains only a minor part of the ozone-rain relationship in multiple correlations. PMID:17740697

  6. Ames ER-2 ozone measurements

    NASA Technical Reports Server (NTRS)

    Pearson, R., Jr.; Vedder, James F.; Starr, W. L.

    1990-01-01

    The objective of this research is to study ozone (O3) in the stratosphere. Measurements of the ozone mixing ratio at 1 s intervals are obtained with an ultraviolet photometer which flies on the ER-2 aircraft. The photometer determines the amount of ozone in air by measuring the transmission of ultraviolet light through a fixed path with and without ambient O3 present.

  7. Tropospheric ozone measurements at the equatorial region (1980-1988)

    NASA Technical Reports Server (NTRS)

    Ilyas, Mohammad

    1994-01-01

    Results from surface ozone measurements at Penang (5.5 deg N, 100 deg E) over 1980-88 period are presented. The study indicates the ozone concentrations undergoing significant diurnal and seasonal variations. The peak concentration are observed at around mid-day (up to 35 nb) but the O3 concentration generally drops to zero level in the early evening and remains unchanged until mid-morning. Monthly-averaged daily 1-h average concentrations are generally small (4-13 nb) and decrease continually from the early part of the year to the end. Frequently, varying local weather conditions seem to influence the O3 concentrations.

  8. Ozone depletion by hydrofluorocarbons

    NASA Astrophysics Data System (ADS)

    Hurwitz, Margaret M.; Fleming, Eric L.; Newman, Paul A.; Li, Feng; Mlawer, Eli; Cady-Pereira, Karen; Bailey, Roshelle

    2015-10-01

    Atmospheric concentrations of hydrofluorocarbons (HFCs) are projected to increase considerably in the coming decades. Chemistry climate model simulations forced by current projections show that HFCs will impact the global atmosphere increasingly through 2050. As strong radiative forcers, HFCs increase tropospheric and stratospheric temperatures, thereby enhancing ozone-destroying catalytic cycles and modifying the atmospheric circulation. These changes lead to a weak depletion of stratospheric ozone. Simulations with the NASA Goddard Space Flight Center 2-D model show that HFC-125 is the most important contributor to HFC-related atmospheric change in 2050; its effects are comparable to the combined impacts of HFC-23, HFC-32, HFC-134a, and HFC-143a. Incorporating the interactions between chemistry, radiation, and dynamics, ozone depletion potentials (ODPs) for HFCs range from 0.39 × 10-3 to 30.0 × 10-3, approximately 100 times larger than previous ODP estimates which were based solely on chemical effects.

  9. Impacts of Ozone-vegetation Interactions and Biogeochemical Feedbacks on Atmospheric Composition and Air Quality Under Climate Change

    NASA Astrophysics Data System (ADS)

    Sadeke, M.; Tai, A. P. K.; Lombardozzi, D.; Val Martin, M.

    2015-12-01

    Surface ozone pollution is one of the major environmental concerns due to its damaging effects on human and vegetation. One of the largest uncertainties of future surface ozone prediction comes from its interaction with vegetation under a changing climate. Ozone can be modulated by vegetation through, e.g., biogenic emissions, dry deposition and transpiration. These processes are in turn affected by chronic exposure to ozone via lowered photosynthesis rate and stomatal conductance. Both ozone and vegetation growth are expected to be altered by climate change. To better understand these climate-ozone-vegetation interactions and possible feedbacks on ozone itself via vegetation, we implement an online ozone-vegetation scheme [Lombardozzi et al., 2015] into the Community Earth System Model (CESM) with active atmospheric chemistry, climate and land surface components. Previous overestimation of surface ozone in eastern US, Canada and Europe is shown to be reduced by >8 ppb, reflecting improved model-observation comparison. Simulated surface ozone is lower by 3.7 ppb on average globally. Such reductions (and improvements) in simulated ozone are caused mainly by lower isoprene emission arising from reduced leaf area index in response to chronic ozone exposure. Effects via transpiration are also potentially significant but require better characterization. Such findings suggest that ozone-vegetation interaction may substantially alter future ozone simulations, especially under changing climate and ambient CO2 levels, which would further modulate ozone-vegetation interactions. Inclusion of such interactions in Earth system models is thus necessary to give more realistic estimation and prediction of surface ozone. This is crucial for better policy formulation regarding air quality, land use and climate change mitigation. Reference list: Lombardozzi, D., et al. "The Influence of Chronic Ozone Exposure on Global Carbon and Water Cycles." Journal of Climate 28.1 (2015): 292-305.

  10. Ozone depletion observed by the Airborne Submillimeter Radiometer (ASUR) during the Arctic winter 1999/2000

    NASA Astrophysics Data System (ADS)

    Bremer, Holger; von KöNig, M.; KleinböHl, A.; Küllmann, H.; Künzi, K.; Bramstedt, K.; Burrows, J. P.; Eichmann, K.-U.; Weber, M.; Goede, A. P. H.

    2002-10-01

    In the winter 1999/2000 the Airborne Submillimeter Radiometer (ASUR) participated in the Stratospheric Aerosol and Gas Experiment III Ozone Loss and Validation Experiment/Third European Stratospheric Experiment on Ozone project on board the NASA research aircraft DC-8. During three deployments in early December 1999, late January, and early March 2000, the ASUR instrument took various measurements of ozone and key species related to stratospheric ozone chemistry. After the sunlight reached the vortex region in January 2000 peak values of about 1.8 ppb ClO were measured by ASUR. There was nearly no ozone destruction observed during the period between mid December 1999 and late January 2000. As expected from ASUR observation of high chlorine activation and continuously low temperatures until mid March, significant ozone depletion was observed between late January and mid March 2000. In order to determine ozone loss it is important to separate dynamical and chemical effects. Since N2O is a good tracer due to its chemical stability in the lower stratosphere for determining ozone changes due to descent of air, ozone loss can be estimated from simultaneous measurements of ozone and N2O by ASUR. Between mid December 1999 and mid March 2000 a chemical ozone loss of about 30% (eq 1.1 ppm) in the altitude range between 19.0 and 22.2 km and of about 40% (eq 1.15 ppm) between 16.0 and 18.1 km was observed. The air masses subsided 2.1-3.2 km in the lower stratosphere due to diabatic descent in the period from mid December 1999 to mid March 2000 as derived from ASUR N2O measurements. Vortex-averaged ASUR measurements of ozone are systematical greater than results from the Global Ozone Monitoring Experiment (GOME) which has a similar vertical resolution than ASUR. This, however, has little impact on the determination of delta ozone and chemical loss estimates.

  11. Mass and Ozone Fluxes from the Lowermost Stratosphere

    NASA Technical Reports Server (NTRS)

    Schoeberl, Mark R.; Olsen, Mark A.

    2004-01-01

    Net mass flux from the stratosphere to the troposphere can be computed from the heating rate along the 380K isentropic surface and the time rate of change of the mass of the lowermost stratosphere (the region between the tropopause and the 380K isentrope). Given this net mass flux and the cross tropopause diabatic mass flux, the residual adiabatic mass flux across the tropopause can also be estimated. These fluxes have been computed using meteorological fields from a free-running general circulation model (FVGCM) and two assimilation data sets, FVDAS, and UKMO. The data sets tend to agree that the annual average net mass flux for the Northern Hemisphere is about 1P10 kg/s. There is less agreement on the southern Hemisphere flux that might be half as large. For all three data sets, the adiabatic mass flux is computed to be from the upper troposphere into the lowermost stratosphere. This flux will dilute air entering from higher stratospheric altitudes. The mass fluxes are convolved with ozone mixing ratios from the Goddard 3D CTM (which uses the FVGCM) to estimate the cross-tropopause transport of ozone. A relatively large adiabatic flux of tropospheric ozone from the tropical upper troposphere into the extratropical lowermost stratosphere dilutes the stratospheric air in the lowermost stratosphere. Thus, a significant fraction of any measured ozone STE may not be ozone produced in the higher Stratosphere. The results also illustrate that the annual cycle of ozone concentration in the lowermost stratosphere has as much of a role as the transport in the seasonal ozone flux cycle. This implies that a simplified calculation of ozone STE mass from air mass and a mean ozone mixing ratio may have a large uncertainty.

  12. SAGE II Ozone Analysis

    NASA Technical Reports Server (NTRS)

    Cunnold, Derek; Wang, Ray

    2002-01-01

    Publications from 1999-2002 describing research funded by the SAGE II contract to Dr. Cunnold and Dr. Wang are listed below. Our most recent accomplishments include a detailed analysis of the quality of SAGE II, v6.1, ozone measurements below 20 km altitude (Wang et al., 2002 and Kar et al., 2002) and an analysis of the consistency between SAGE upper stratospheric ozone trends and model predictions with emphasis on hemispheric asymmetry (Li et al., 2001). Abstracts of the 11 papers are attached.

  13. A Multi-sensor Upper Tropospheric Ozone Product (MUTOP) based on TES ozone and GOES water vapor: derivation

    NASA Astrophysics Data System (ADS)

    Felker, S. R.; Moody, J. L.; Wimmers, A. J.; Osterman, G.; Bowman, K.

    2010-12-01

    The Tropospheric Emission Spectrometer (TES), a hyperspectral infrared instrument on the Aura satellite, retrieves a vertical profile of tropospheric ozone. However, polar-orbiting instruments like TES provide limited nadir-view coverage. This work illustrates the value of these observations when taken in context with information about synoptic-scale weather patterns. The goal of this study is to create map-view products of upper troposphere (UT) ozone through the integration of TES ozone measurements with two synoptic dynamical tracers of stratospheric influence: specific humidity derived from the GOES Imager, and potential vorticity from an operational forecast model. As a mixing zone between tropospheric and stratospheric reservoirs, the upper troposphere (UT) exhibits a complex chemical makeup. Determination of ozone mixing ratios in this layer is especially difficult without direct in-situ measurement. However, it is well understood that UT ozone is correlated with dynamical tracers like low specific humidity and high potential vorticity. Blending the advantages of two remotely sensed quantities (GOES water vapor and TES ozone) is at the core of the Multi-sensor Upper Tropospheric Ozone Product (MUTOP). Our approach results in the temporal and spatial coverage of a geostationary platform, a major improvement over individual polar overpasses, while retaining TES's ability to characterize UT ozone. Results suggest that over 70% of TES-observed UT ozone variability can be explained by correlation with the two dynamical tracers. MUTOP reproduces TES retrievals across the GOES-West domain with a root mean square error (RMSE) of 19.2 ppbv. There are several advantages to this multi-sensor derived product approach: (1) it is calculated from 2 operational fields (GOES specific humidity and GFS PV), so the layer-average ozone can be created and used in near real-time; (2) the product provides the spatial resolution and coverage of a geostationary platform as it depicts

  14. Surface Ozone in the Lake Tahoe Basin

    NASA Astrophysics Data System (ADS)

    Burley, J. D.; Bytnerowicz, A.; Zielinska, B.; Schilling, S.

    2014-12-01

    Surface ozone (O3) concentrations were measured in and around the Lake Tahoe Basin using both active monitors (12 sites in 2010) and passive samplers (31 sites 2002; 34 sites in 2010). The 2010 data from active monitors indicate average summertime diurnal maxima of approximately 50-55 ppb. Minimal site-to-site variability is observed within the Basin during the well-mixed hours of 10:00 to 17:00 PST, but large differences between different sites are observed in the late evening and pre-dawn hours. The observed trends correlate most strongly with elevation, topography, and surface vegetation. High elevation sites with steeply sloped topography and drier ground cover experience elevated O3 concentrations throughout the night because they maintain good access to downward mixing of ozone-rich air from aloft with minimal losses due to dry deposition. Low elevation sites with flat topography and wetter surface vegetation experience low O3 concentrations in the pre-dawn hours because of greatly reduced downward mixing coupled with enhanced O3 removal via efficient dry deposition. Very high average O3 concentrations (overall seasonal average = 64 ppb) were measured with passive samplers in the middle of the Lake in 2010. This latter finding may reflect high emissions of O3 precursors from vehicular traffic around the Lake, emissions from motorboats, and/or elevated rates of photochemical processes due to high solar radiation and stagnant air masses over the Lake. Tahoe Basin sites with good nocturnal exposure to ozone-rich air from aloft experience average O3 concentrations that are frequently higher than concurrent averages from the polluted upwind comparison sites of Sacramento, Folsom, and Placerville.

  15. Surface ozone exposures measured at clean locations around the world.

    PubMed

    Lefohn, A S; Krupa, S V; Winstanley, D

    1990-01-01

    experienced ozone exposures in the range between those values experienced at the South Pole and Mauna Loa NOAA GMCC sites. The 7-month average of the daily 7 h average ozone concentration at 'clean' sites located in the continental United States and southern Canada ranged from 0.028 to 0.050 ppm. Our analysis indicates that seasonal 7 h average values of 0.025 ppm and below, used by some vegetation researchers as a reference point, may be too low and that estimates of crop losses and tree damage in many locations may have been too high. Our analysis indicates that a more appropriate reference point in North America might be between 0.030 and 0.045 ppm. We have observed that the subtle effects of changing distribution patterns of hourly average ozone concentrations may be obscured with the use of exposure indices such as the monthly average. Future assessments of the effects associated with ground-level ozone should involve the use of exposure indices sensitive to changes in the distribution patterns of hourly average ozone concentrations. PMID:15092317

  16. Ozone and nitrogen dioxide above the northern Tien Shan

    NASA Technical Reports Server (NTRS)

    Arefev, Vladimir N.; Volkovitsky, Oleg A.; Kamenogradsky, Nikita E.; Semyonov, Vladimir K.; Sinyakov, Valery P.

    1994-01-01

    The results of systematic perennial measurements of the total ozone (since 1979) and nitrogen dioxide column (since 1983) in the atmosphere in the European-Asian continent center above the mountainmass of the Tien Shan are given. This region is distinguished by a great number of sunny days during a year. The observation station is at the Northern shore of Issyk Kul Lake (42.56 N 77.04 E 1650 m above the sea level). The measurement results are presented as the monthly averaged atmospheric total ozone and NO2 stratospheric column abundances (morning and evening). The peculiarities of seasonal variations of ozone and nitrogen dioxide atmospheric contents, their regular variances with a quasi-biennial cycles and trends have been noticed. Irregular variances of ozone and nitrogen dioxide atmospheric contents, i.e. their positive and negative anomalies in the monthly averaged contents relative to the perennial averaged monthly means, have been analyzed. The synchronous and opposite in phase anomalies in variations of ozone and nitrogen dioxide atmospheric contents were explained by the transport and zonal circulation in the stratosphere (Kamenogradsky et al., 1990).

  17. Precision ozone vapor pressure measurements

    NASA Technical Reports Server (NTRS)

    Hanson, D.; Mauersberger, K.

    1985-01-01

    The vapor pressure above liquid ozone has been measured with a high accuracy over a temperature range of 85 to 95 K. At the boiling point of liquid argon (87.3 K) an ozone vapor pressure of 0.0403 Torr was obtained with an accuracy of + or - 0.7 percent. A least square fit of the data provided the Clausius-Clapeyron equation for liquid ozone; a latent heat of 82.7 cal/g was calculated. High-precision vapor pressure data are expected to aid research in atmospheric ozone measurements and in many laboratory ozone studies such as measurements of cross sections and reaction rates.

  18. Karlson ozone sterilizer. Final report

    SciTech Connect

    Karlson, E.

    1984-05-07

    The authors have a functional sterilization system employing ozone as a sterilization agent. This final report covers the work that led to the first medical sterilizer using ozone as the sterilizing agent. The specifications and the final design were set by hospital operating room personnel and public safety standards. Work on kill tests using bacteria, viruses and fungi determined the necessary time and concentration of ozone necessary for sterilization. These data were used in the Karlson Ozone Sterilizer to determine the length of the steps of the operating cycle and the concentration of ozone to be used. 27 references.

  19. Total Ozone Prediction: Stratospheric Dynamics

    NASA Technical Reports Server (NTRS)

    Jackman, Charles H.; Kawa, S. Ramdy; Douglass, Anne R.

    2003-01-01

    The correct prediction of total ozone as a function of latitude and season is extremely important for global models. This exercise tests the ability of a particular model to simulate ozone. The ozone production (P) and loss (L) will be specified from a well- established global model and will be used in all GCMs for subsequent prediction of ozone. This is the "B-3 Constrained Run" from M&MII. The exercise mostly tests a model stratospheric dynamics in the prediction of total ozone. The GCM predictions will be compared and contrasted with TOMS measurements.

  20. Dissociating Averageness and Attractiveness: Attractive Faces Are Not Always Average

    ERIC Educational Resources Information Center

    DeBruine, Lisa M.; Jones, Benedict C.; Unger, Layla; Little, Anthony C.; Feinberg, David R.

    2007-01-01

    Although the averageness hypothesis of facial attractiveness proposes that the attractiveness of faces is mostly a consequence of their averageness, 1 study has shown that caricaturing highly attractive faces makes them mathematically less average but more attractive. Here the authors systematically test the averageness hypothesis in 5 experiments…

  1. Validation of OMI total ozone retrievals from the SAO ozone profile algorithm and three operational algorithms with Brewer measurements

    NASA Astrophysics Data System (ADS)

    Bak, J.; Liu, X.; Kim, J. H.; Chance, K.; Haffner, D. P.

    2015-01-01

    The accuracy of total ozone computed from the Smithsonian Astrophysical Observatory (SAO) optimal estimation (OE) ozone profile algorithm (SOE) applied to the Ozone Monitoring Instrument (OMI) is assessed through comparisons with ground-based Brewer spectrometer measurements from 2005 to 2008. We also compare the three OMI operational ozone products, derived from the NASA Total Ozone Mapping Spectrometer (TOMS) algorithm, the KNMI (Royal Netherlands Meteorological Institute) differential optical absorption spectroscopy (DOAS) algorithm, and KNMI's Optimal Estimation (KOE) algorithm. The best agreement is observed between SAO and Brewer, with a mean difference of within 1% at most individual stations. The KNMI OE algorithm systematically overestimates Brewer total ozone by 2% at low and mid-latitudes and 5% at high latitudes while the TOMS and DOAS algorithms underestimate it by ~1.65% on average. Standard deviations of ~1.8% are calculated for both SOE and TOMS, but DOAS and KOE have higher values of 2.2% and 2.6%, respectively. The stability of the SOE algorithm is found to have insignificant dependence on viewing geometry, cloud parameters, or total ozone column. In comparison, the KOE-Brewer differences are significantly correlated with solar and viewing zenith angles and show significant deviations depending on cloud parameters and total ozone amount. The TOMS algorithm exhibits similar stability to SOE with respect to viewing geometry and total column ozone, but has stronger cloud parameter dependence. The dependence of DOAS on observational geometry and geophysical conditions is marginal compared to KOE, but is distinct compared to the SOE and TOMS algorithms. Comparisons of all four OMI products with Brewer show no apparent long-term drift, but seasonal features are evident, especially for KOE and TOMS. The substantial differences in the KOE vs. SOE algorithm performance cannot be sufficiently explained by the use of soft calibration (in SOE) and the use of

  2. Distribution of injury and microdosimetry of ozone in the ventilatory unit of the rat

    SciTech Connect

    Pinkerton, K.E.; Mercer, R.R.; Plopper, C.G.; Crapo, J.D. )

    1992-09-01

    The distribution of ozone-induced injury across ventilatory units of the lungs was determined and compared with the predicted distribution of ozone dose across the same units to evaluate dose-response relationships. Sprague-Dawley rats were exposed to either 0.98 ppm ozone 8 h/day for 90 days or to filtered air only. En bloc microdissection was used to identify and isolate in longitudinal profile the bronchiole-alveolar duct junction, first pair of alveolar duct generations, and intervening bifurcation ridge. The first alveolar outpocketing along the bronchiolar wall of each isolation was used to identify the center of a series of concentric arcs radiating outward at 100-microns intervals across each ventilatory unit. The intercept lengths of each arc with the tissue of alveolar septal tips (edges) and alveolar walls were measured and expressed as a function of distance into the ventilatory unit. Relative ozone dose across the ventilatory unit was estimated using the geometry of the tracheobronchial tree and the volume and surface area distribution within individual ventilatory units. This mathematical model of ozone dose demonstrated a high degree of correlation to this measured tissue injury response. The findings of this study demonstrate that microdosimetry and microtoxicology can be used to determine dose-response relationships within the ventilatory unit and to assess questions of tissue sensitivity in ozone-induced lung injury.

  3. Identifying sources of ozone to three rural locations in Nevada, USA, using ancillary gas pollutants, aerosol chemistry, and mercury.

    PubMed

    Miller, Matthieu B; Fine, Rebekka; Pierce, Ashley M; Gustin, Mae S

    2015-10-15

    Ozone (O3) is a secondary air pollutant of long standing and increasing concern for environmental and human health, and as such, the US Environmental Protection Agency will revise the National Ambient Air Quality Standard of 75 ppbv to ≤ 70 ppbv. Long term measurements at the Great Basin National Park (GBNP) indicate that O3 in remote areas of Nevada will exceed a revised standard. As part of the Nevada Rural Ozone Initiative, measurements of O3 and other air pollutants were made at 3 remote sites between February 2012 and March 2014, GBNP, Paradise Valley (PAVA), and Echo Peak (ECHO). Exceptionally high concentrations of each air pollutant were defined relative to each site as mixing ratios that exceeded the 90th percentile of all hourly data. Case studies were analyzed for all periods during which mean daily O3 exceeded the 90th percentile concurrently with a maximum 8-h average (MDA8) O3 that was "exceptionally high" for the site (65 ppbv at PAVA, 70 ppbv at ECHO and GBNP), and of potential regulatory significance. An MDA8 ≥ 65 ppbv occurred only five times at PAVA, whereas this occurred on 49 and 65 days at GBNP and ECHO, respectively. The overall correlation between O3 and other pollutants was poor, consistent with the large distance from significant primary emission sources. Mean CO at these locations exceeded concentrations reported for background sites in 2000. Trajectory residence time calculations and air pollutant concentrations indicate that exceedances at GBNP and ECHO were promoted by air masses originating from multiple sources, including wildfires, transport of pollution from southern California and the marine boundary layer, and transport of Asian pollution plumes. Results indicate that the State of Nevada will exceed a revised O3 standard due to sources that are beyond their control. PMID:25957787

  4. TOMS Tropical Tropospheric Ozone Data Sets at the University of Maryland Website

    NASA Technical Reports Server (NTRS)

    Kochhar, A. K.; Thompson, A. M.; Hudson, R. D.; Frolov, A. D.; Witte, J. C.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Since 1997, shortly after the launch of the Earth-Probe TOMS (Total Ozone Mapping Spectrometer) satellite instrument, we have been processing data in near-real time to post maps of tropical tropospheric ozone at a website: metosrv2.umd.edu/-tropo. Daily, 3-day and 9-day averages of tropical tropospheric ozone column depth (TTO) are viewable from 10N to 10S. Data can be downloaded (running 9-day means) from 20N-30S. Pollution events are trackable along with dynamically-induced variations in tropospheric ozone column. TOMS smoke aerosol (toms.gsfc.nasa.gov) can be used to interpret biomass burning ozone, as for example, during the extreme ozone and smoke pollution period during the ENSO-related fires of August November 1997. During that time plumes of ozone and smoke were frequently decoupled and ozone from Indonesian fires and from Africa merged in one large feature by late October 1997. In addition to the Earth-Probe TOMS record, data as half-month averages and as daily 9-day means from the Nimbus 7 TOMS instrument are at the metosrv2.umd.edu/-tropo website. A guide to the website and examples of ozone time-series and maps will be shown.

  5. Assimilation of Satellite Ozone Observations

    NASA Technical Reports Server (NTRS)

    Stajner, I.; Winslow, N.; Wargan, K.; Hayashi, H.; Pawson, S.; Rood, R.

    2003-01-01

    This talk will discuss assimilation of ozone data from satellite-borne instruments. Satellite observations of ozone total columns and profiles have been measured by a series of Total Ozone Mapping Spectrometer (TOMS), Solar Backscatter Ultraviolet (SBUV) instruments, and more recently by the Global Ozone Monitoring Experiment. Additional profile data are provided by instruments on NASA's Upper Atmosphere Research Satellite and by occultation instruments on other platforms. Instruments on Envisat' and future EOS Aura satellite will supply even more comprehensive data about the ozone distribution. Satellite data contain a wealth of information, but they do not provide synoptic global maps of ozone fields. These maps can be obtained through assimilation of satellite data into global chemistry and transport models. In the ozone system at NASA's Data Assimilation Office (DAO) any combination of TOMS, SBUV, and Microwave Limb sounder (MLS) data can be assimilated. We found that the addition of MLS to SBUV and TOMS data in the system helps to constrain the ozone distribution, especially in the polar night region and in the tropics. The assimilated ozone distribution in the troposphere and lower stratosphere is sensitive also to finer changes in the SBUV and TOMS data selection and to changes in error covariance models. All results are established by comparisons of assimilated ozone with independent profiles from ozone sondes and occultation instruments.

  6. Application of Ultrasound and Ozone for the Removal of Aqueous Tannin

    NASA Astrophysics Data System (ADS)

    Son, Younggyu; Lim, Junghyun; Cui, Mingcan; Lim, Myunghee; Kweon, Bo-Youn; Khim, Jeehyeong

    2009-07-01

    In order to investigate the enhancement of combination of ultrasound process and ozonation for the removal of aqueous tannin, tannin concentration, chemical oxygen demand (COD), and total organic carbon (TOC) were analyzed in ultrasound process, ozonation, and ultrasound/ozone process. Even though ultrasound process was not effective for the removal of aqueous in terms of tannin concentration, COD, and TOC, ultrasound process could enhance the removal efficiency significantly when it was combined with ozonation. It was also revealed that COD removal resulted in partly mineralization due to insufficient oxidation power, which was induced by ultrasound and ozone. However average oxidation state of all organics in the solution was increased cogently and as a result, biodegradability could be increased meaningfully. Therefore ultrasound/ozone process could be effective pre-treatment process to biological process for the removal of aqueous tannin.

  7. Impact of EOS MLS ozone data on medium-extended range ensemble weather forecasts

    NASA Astrophysics Data System (ADS)

    Cheung, J. C. H.; Haigh, J. D.; Jackson, D. R.

    2014-08-01

    As the stratosphere is largely characterized by its ozone abundance, the quality of the ozone field is important for a realistic representation of the stratosphere in weather and climate models. While the stratosphere is directly affected by radiative heating from ozone photodissociation, ozone abundance might also impact the representation of the troposphere since the stratosphere and troposphere are dynamically linked. In this paper, we examine the potential benefits of using ozone data from the Earth Observing System (EOS) Microwave Limb Sounder (MLS) for medium-extended range tropospheric forecasts in a current numerical weather prediction system. The global component of the Met Office Global and Regional Ensemble Prediction System is used, which is run at a resolution of N216 L85 with 24 ensemble members. We compare two scenarios of 31 day forecasts covering the same period, one with the current operational ozone climatology and the other with a monthly mean zonally averaged ozone field computed from the MLS data set. In the extreme case of the Arctic "ozone hole" of March 2011, our results show a general reduction in stratospheric forecast errors in the tropics and Southern Hemisphere as a result of the improved representation of ozone. However, even in such a scenario, where the MLS ozone field is much superior to that of the control, we find that tropospheric forecast errors in the medium-extended range are dominated by the spread of ensemble members and no significant reduction in the root-mean-square forecast errors.

  8. Arctic ozone loss in threshold conditions: Match observations in 1997/1998 and 1998/1999

    NASA Astrophysics Data System (ADS)

    Schulz, A.; Rex, M.; Harris, N. R. P.; Braathen, G. O.; Reimer, E.; Alfier, R.; Kilbane-Dawe, I.; Eckermann, S.; Allaart, M.; Alpers, M.; Bojkov, B.; Cisneros, J.; Claude, H.; Cuevas, E.; Davies, J.; Backer, H. De; Dier, H.; Dorokhov, V.; Fast, H.; Godin, S.; Johnson, B.; Kois, B.; Kondo, Y.; Kosmidis, E.; Kyrö, E.; Litynska, Z.; Mikkelsen, I. S.; Molyneux, M. J.; Murphy, G.; Nagai, T.; Nakane, H.; O'Connor, F.; Parrondo, C.; Schmidlin, F. J.; Skrivankova, P.; Varotsos, C.; Vialle, C.; Viatte, P.; Yushkov, V.; Zerefos, C.; von der Gathen, P.

    2001-04-01

    Chemical ozone loss rates inside the Arctic polar vortex were determined in early 1998 and early 1999 by using the Match technique based on coordinated ozonesonde measurements. These two winters provide the only opportunities in recent years to investigate chemical ozone loss in a warm Arctic vortex under threshold conditions, i.e., where the preconditions for chlorine activation, and hence ozone destruction, only occurred occasionally. In 1998, results were obtained in January and February between 410 and 520 K. The overall ozone loss was observed to be largely insignificant, with the exception of late February, when those air parcels exposed to temperatures below 195 K were affected by chemical ozone loss. In 1999, results are confined to the 475 K isentropic level, where no significant ozone loss was observed. Average temperatures were some 8°-10° higher than those in 1995, 1996, and 1997, when substantial chemical ozone loss occurred. The results underline the strong dependence of the chemical ozone loss on the stratospheric temperatures. This study shows that enhanced chlorine alone does not provide a sufficient condition for ozone loss. The evolution of stratospheric temperatures over the next decade will be the determining factor for the amount of wintertime chemical ozone loss in the Arctic stratosphere.

  9. Climate-driven ground-level ozone extreme in the fall over the Southeast United States.

    PubMed

    Zhang, Yuzhong; Wang, Yuhang

    2016-09-01

    Ground-level ozone is adverse to human and vegetation health. High ground-level ozone concentrations usually occur over the United States in the summer, often referred to as the ozone season. However, observed monthly mean ozone concentrations in the southeastern United States were higher in October than July in 2010. The October ozone average in 2010 reached that of July in the past three decades (1980-2010). Our analysis shows that this extreme October ozone in 2010 over the Southeast is due in part to a dry and warm weather condition, which enhances photochemical production, air stagnation, and fire emissions. Observational evidence and modeling analysis also indicate that another significant contributor is enhanced emissions of biogenic isoprene, a major ozone precursor, from water-stressed plants under a dry and warm condition. The latter finding is corroborated by recent laboratory and field studies. This climate-induced biogenic control also explains the puzzling fact that the two extremes of high October ozone both occurred in the 2000s when anthropogenic emissions were lower than the 1980s and 1990s, in contrast to the observed decreasing trend of July ozone in the region. The occurrences of a drying and warming fall, projected by climate models, will likely lead to more active photochemistry, enhanced biogenic isoprene and fire emissions, an extension of the ozone season from summer to fall, and an increase of secondary organic aerosols in the Southeast, posing challenges to regional air quality management. PMID:27551089

  10. Ozone Production In The Upper Troposphere

    NASA Astrophysics Data System (ADS)

    Phillips, G. J.; Actoleicester Team

    A box modelling study has been carried out using data obtained from the UK -NERC funded UTLS-OZONE and EXPORT measurement campaigns. Data from the campaigns was used to constrain the model and the subsequent results were used to calculate ozone tendencies within air mass types encountered. Both average and air mass specific analyses were carried out. These campaigns were conducted during the spring and summer of 2000 respectively, onboard the UKMO C-130 Hercules aircraft. The spring data was taken mainly from the north Atlantic, west of Scotland, and the summer data was collected over central Europe. Five-day back trajectories calculated from ECMWF wind fields by the Universities of Reading and Cambridge were used to separate the data for analysis.

  11. Evaluation of Global Ozone Monitoring Experiment (GOME) ozone profiles from nine different algorithms

    NASA Astrophysics Data System (ADS)

    Meijer, Y. J.; Swart, D. P. J.; Baier, F.; Bhartia, P. K.; Bodeker, G. E.; Casadio, S.; Chance, K.; Del Frate, F.; Erbertseder, T.; Felder, M. D.; Flynn, L. E.; Godin-Beekmann, S.; Hansen, G.; Hasekamp, O. P.; Kaifel, A.; Kelder, H. M.; Kerridge, B. J.; Lambert, J.-C.; Landgraf, J.; Latter, B.; Liu, X.; McDermid, I. S.; Pachepsky, Y.; Rozanov, V.; Siddans, R.; Tellmann, S.; van der A, R. J.; van Oss, R. F.; Weber, M.; Zehner, C.

    2006-11-01

    An evaluation is made of ozone profiles retrieved from measurements of the nadir-viewing Global Ozone Monitoring Experiment (GOME) instrument. Currently, four different approaches are used to retrieve ozone profile information from GOME measurements, which differ in the use of external information and a priori constraints. In total nine different algorithms will be evaluated exploiting the optimal estimation (Royal Netherlands Meteorological Institute, Rutherford Appleton Laboratory, University of Bremen, National Oceanic and Atmospheric Administration, Smithsonian Astrophysical Observatory), Phillips-Tikhonov regularization (Space Research Organization Netherlands), neural network (Center for Solar Energy and Hydrogen Research, Tor Vergata University), and data assimilation (German Aerospace Center) approaches. Analysis tools are used to interpret data sets that provide averaging kernels. In the interpretation of these data, the focus is on the vertical resolution, the indicative altitude of the retrieved value, and the fraction of a priori information. The evaluation is completed with a comparison of the results to lidar data from the Network for Detection of Stratospheric Change stations in Andoya (Norway), Observatoire Haute Provence (France), Mauna Loa (Hawaii), Lauder (New Zealand), and Dumont d'Urville (Antarctic) for the years 1997-1999. In total, the comparison involves nearly 1000 ozone profiles and allows the analysis of GOME data measured in different global regions and hence observational circumstances. The main conclusion of this paper is that unambiguous information on the ozone profile can at best be retrieved in the altitude range 15-48 km with a vertical resolution of 10 to 15 km, precision of 5-10%, and a bias up to 5% or 20% depending on the success of recalibration of the input spectra. The sensitivity of retrievals to ozone at lower altitudes varies from scheme to scheme and includes significant influence from a priori assumptions.

  12. The Ozone Show.

    ERIC Educational Resources Information Center

    Mathieu, Aaron

    2000-01-01

    Uses a talk show activity for a final assessment tool for students to debate about the ozone hole. Students are assessed on five areas: (1) cooperative learning; (2) the written component; (3) content; (4) self-evaluation; and (5) peer evaluation. (SAH)

  13. Ozone decomposing filter

    DOEpatents

    Simandl, Ronald F.; Brown, John D.; Whinnery, Jr., LeRoy L.

    1999-01-01

    In an improved ozone decomposing air filter carbon fibers are held together with a carbonized binder in a perforated structure. The structure is made by combining rayon fibers with gelatin, forming the mixture in a mold, freeze-drying, and vacuum baking.

  14. Ozone and temperature trends

    NASA Technical Reports Server (NTRS)

    Labitzke, K.; Miller, A. J.; Angell, J.; Deluisi, J.; Frederick, J.; Logan, J.; Mateer, C.; Naujokat, B.; Reinsel, G.; Tiao, G.

    1985-01-01

    The measurement of temporal changes in ozone and temperature are discussed. The data are examined within the context of natural atmospheric variability and data problems. The results are compared to numerical model calculations. The major issues are defined in terms of goal achievement. Each parameter is considered in terms of instrument type, long term effects, and altitude.

  15. Ozone decomposing filter

    SciTech Connect

    Simandl, R.F.; Brown, J.D.; Whinnery, L.L. Jr.

    1999-11-02

    In an improved ozone decomposing air filter carbon fibers are held together with a carbonized binder in a perforated structure. The structure is made by combining rayon fibers with gelatin, forming the mixture in a mold, freeze-drying, and vacuum baking.

  16. Ozone Layer Educator's Guide.

    ERIC Educational Resources Information Center

    Environmental Protection Agency, Washington, DC.

    This guide has been developed through a collaborative effort involving the U.S. Environmental Protection Agency (EPA), the National Oceanic and Atmospheric Administration (NOAA), and the National Aeronautics and Space Administration (NASA). It is part of an ongoing commitment to ensure that the results of scientific research on ozone depletion are…

  17. Dobson ozone spectrophotometer modification.

    NASA Technical Reports Server (NTRS)

    Komhyr, W. D.; Grass, R. D.

    1972-01-01

    Description of a modified version of the Dobson ozone spectrophotometer in which several outdated electronic design features have been replaced by circuitry embodying more modern design concepts. The resulting improvement in performance characteristics has been obtained without changing the principle of operation of the original instrument.

  18. Revisiting Antarctic Ozone Depletion

    NASA Astrophysics Data System (ADS)

    Grooß, Jens-Uwe; Tritscher, Ines; Müller, Rolf

    2015-04-01

    Antarctic ozone depletion is known for almost three decades and it has been well settled that it is caused by chlorine catalysed ozone depletion inside the polar vortex. However, there are still some details, which need to be clarified. In particular, there is a current debate on the relative importance of liquid aerosol and crystalline NAT and ice particles for chlorine activation. Particles have a threefold impact on polar chlorine chemistry, temporary removal of HNO3 from the gas-phase (uptake), permanent removal of HNO3 from the atmosphere (denitrification), and chlorine activation through heterogeneous reactions. We have performed simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) employing a recently developed algorithm for saturation-dependent NAT nucleation for the Antarctic winters 2011 and 2012. The simulation results are compared with different satellite observations. With the help of these simulations, we investigate the role of the different processes responsible for chlorine activation and ozone depletion. Especially the sensitivity with respect to the particle type has been investigated. If temperatures are artificially forced to only allow cold binary liquid aerosol, the simulation still shows significant chlorine activation and ozone depletion. The results of the 3-D Chemical Transport Model CLaMS simulations differ from purely Lagrangian longtime trajectory box model simulations which indicates the importance of mixing processes.

  19. Ensemble simulations of the role of the stratosphere in the attribution of northern extratropical tropospheric ozone variability

    NASA Astrophysics Data System (ADS)

    Hess, P.; Kinnison, D.; Tang, Q.

    2015-03-01

    Despite the need to understand the impact of changes in emissions and climate on tropospheric ozone, the attribution of tropospheric interannual ozone variability to specific processes has proven difficult. Here, we analyze the stratospheric contribution to tropospheric ozone variability and trends from 1953 to 2005 in the Northern Hemisphere (NH) mid-latitudes using four ensemble simulations of the free running (FR) Whole Atmosphere Community Climate Model (WACCM). The simulations are externally forced with observed time-varying (1) sea-surface temperatures (SSTs), (2) greenhouse gases (GHGs), (3) ozone depleting substances (ODS), (4) quasi-biennial oscillation (QBO), (5) solar variability (SV) and (6) stratospheric sulfate surface area density (SAD). A detailed representation of stratospheric chemistry is simulated, including the ozone loss due to volcanic eruptions and polar stratospheric clouds. In the troposphere, ozone production is represented by CH4-NOx smog chemistry, where surface chemical emissions remain interannually constant. Despite the simplicity of its tropospheric chemistry, at many NH measurement locations, the interannual ozone variability in the FR WACCM simulations is significantly correlated with the measured interannual variability. This suggests the importance of the external forcing applied in these simulations in driving interannual ozone variability. The variability and trend in the simulated 1953-2005 tropospheric ozone from 30 to 90° N at background surface measurement sites, 500 hPa measurement sites and in the area average are largely explained on interannual timescales by changes in the 30-90° N area averaged flux of ozone across the 100 hPa surface and changes in tropospheric methane concentrations. The average sensitivity of tropospheric ozone to methane (percent change in ozone to a percent change in methane) from 30 to 90° N is 0.17 at 500 hPa and 0.21 at the surface; the average sensitivity of tropospheric ozone to the 100 h

  20. Impact of greenhouse gases on the Earth's ozone layer

    NASA Astrophysics Data System (ADS)

    Zadorozhny, Alexander

    A numerical 2-D zonally averaged interactive dynamical radiative-photochemical model of the ozonosphere including aerosol physics is used to examine the role of the greenhouse gases CO2 , CH4 , and N2 O in the future long-term changes of the Earth's ozone layer, in particular in its recovery after reduction of anthropogenic discharges of chlorine and bromine compounds into the atmosphere. The model allows calculating self-consistently diabatic circulation, temperature, gaseous composition of the troposphere and stratosphere at latitudes from the South to North Poles, as well as distribution of sulphate aerosol particles and polar stratospheric clouds (PSCs) of types I and II. The scenarios of expected changes of the anthropogenic pollutants for the period from 1980 through 2050 are taken from Climate Change 2001. The processes, which determine the influence of anthropogenic growth of atmospheric abundance of the greenhouse gases on the dynamics of recovery of the Earth's ozone layer, have been studied in details. Expected cooling of the stratosphere caused by increases of greenhouse gases, most importantly CO2 , essentially influences the ozone layer by two ways: through temperature dependencies of the gas phase reaction rates and through enhancement of polar ozone depletion via increased PSC formation. The model calculations show that a weakness in efficiencies of all gas phase catalytic cycles of the ozone destruction due to cooling of the stratosphere is a dominant mechanism of the impact of the greenhouse gases on the ozone layer in Antarctic as well as at the lower latitudes. This mechanism leads to a significant acceleration of the ozone layer recovery here because of the greenhouse gases growth. On the contrary, the mechanism of the impact of the greenhouse gases on the ozone through PSC modification begins to be more effective in Arctic in comparison with the gas phase mechanism in springs after about 2020, which leads to retard the expected recovery of the

  1. Changes in the vertical distribution of ozone over Canada from ozonesondes: 1980-2001

    NASA Astrophysics Data System (ADS)

    Tarasick, D. W.; Fioletov, V. E.; Wardle, D. I.; Kerr, J. B.; Davies, J.

    2005-01-01

    Measurements of the vertical profile of ozone concentration using balloon-borne ECC ozonesondes have been made weekly since 1980 at several sites in Canada (Edmonton, Goose Bay, Churchill, and Resolute), since 1987 at Alert, and since 1992 at Eureka. Previous analyses of ozone trends over Canada have shown strong negative trends in tropospheric ozone. We present here a new analysis of trends in the vertical distribution of ozone with data up to the end of 2001. In addition, more detailed attention is paid to some potential sources of bias: total ozone correction, background current correction, and time-of-launch (diurnal) variation. For the 1980-2001 period the overall linear trends are primarily negative, both in tropospheric and stratospheric ozone. However, when the data for 1991-2001 only are considered, the trends are positive, even in the lower stratosphere. When the time series are compared with previously reported trends (to 1993), it is evident that ozone has rebounded at all levels below about 63 hPa. These differences do not appear to be related to changes in tropopause height, as the average height of the tropopause (as measured over the ozonesonde stations) has not changed over either the 22-year or the 11-year period. Nevertheless, comparison with another dynamical indicator, the wintertime frequency of occurrence of laminae in the ozone profile, suggests that this rebound may be partly a result of small changes in the atmospheric circulation, rather than a recovery of the ozone layer from halocarbon-induced depletion. The long-term trends in average tropospheric ozone concentrations over Canada are similar to corresponding lower stratospheric trends, and tropospheric ozone levels show significant correlation with lower stratospheric ozone amounts.

  2. Moderate drought did not affect the effectiveness of ethylenediurea (EDU) in protecting Populus cathayana from ambient ozone.

    PubMed

    Xin, Yue; Yuan, Xiangyang; Shang, Bo; Manning, William J; Yang, Aizhen; Wang, Younian; Feng, Zhaozhong

    2016-11-01

    A field study was conducted to evaluate the effects of ambient ozone (O3) on an O3-sensitive poplar (Populus cathayana) by using ethylenediurea (EDU) as a chemical protectant under two soil water treatments (well-watered (WW) and moderate drought (MD, 50-60% of WW in volumetric soil water content). EDU was applied as foliar spray at 0, 300, 450, and 600ppm. Photosynthetic parameters, pigment contents, leaf nitrogen, antioxidant capacity, growth, and biomass were measured. The 8h (9:00-17:00) average ambient O3 concentration was 71.7ppb, and AOT40 was 29.2ppmh during the experimental period (9 June to 21 September), which was high enough to cause plant injury. MD had significantly negative effects on P. cathayana, as indicated by reduced photosynthesis, growth, and biomass, and higher MDA contents. On the other hand, EDU significantly increased photosynthesis rate, chlorophyll a fluorescence, Vcmax and Jmax, photosynthetic pigments, total antioxidant capacity, tree growth and biomass accumulation, and reduced lipid peroxidation, but there was no significant interaction between EDU and drought for most parameters, indicating that EDU can efficiently protect Populus cathayana against ambient O3 and the protection was not affected by soil water contents when soil water reached moderate drought level. Among all doses, EDU at 450ppm provided maximum protection. Comparison of EDU-treated and non-treated P. cathayana could be used as a biomarker system in risk assessment of the effects of ambient O3 on forest health. PMID:27424114

  3. Ozone, nitric acid, and ammonia air pollution is unhealthy for people and ecosystems in southern Sierra Nevada, California.

    PubMed

    Cisneros, Ricardo; Bytnerowicz, Andrzej; Schweizer, Donald; Zhong, Sharon; Traina, Samuel; Bennett, Deborah H

    2010-10-01

    Two-week average concentrations of ozone (O3), nitric acid vapor (HNO3) and ammonia (NH3) were measured with passive samplers during the 2002 summer season across the central Sierra Nevada Mountains, California, along the San Joaquin River drainage. Elevated concentrations of the pollutants were determined with seasonal means for individual sites ranging between 62 and 88 ppb for O3, 1.0-3.8 microg m(-3) for HNO3, and 2.6-5.2 microg m(-3) for NH3. Calculated O3 exposure indices were very high, reaching SUM00-191 ppm h, SUM60-151 ppm h, and W126-124 ppm h. Calculated nitrogen (N) dry deposition ranged from 1.4 to 15 kg N ha(-1) for maximum values, and 0.4-8 kg N ha(-1) for minimum values; potentially exceeding Critical Loads (CL) for nutritional N. The U.S., California, and European 8 h O3 human health standards were exceeded during 104, 108, and 114 days respectively, indicating high risk to humans from ambient O3. PMID:20708832

  4. Effect of some climatic parameters on tropospheric and total ozone column over Alipore ( 22.52 ∘ N, 88.33 ∘ E), India

    NASA Astrophysics Data System (ADS)

    Jana, P. K.; Bhattacharyya, S.; Banerjee, A.

    2014-10-01

    The paper presents the nature of variations of tropospheric and total ozone column retrieved from the Convective Cloud Differential (CCD) technique, Ozone Monitoring Instrument (OMI), and Total Ozone Mapping Spectrometer (TOMS) data, National Aeronautics and Space Administrations (NASA), USA, respectively; surface temperature, relative humidity, total rainfall, ozone precursors (non-methane hydrocarbon, carbon monoxide, nitrogen dioxide, and sulphur dioxide) that are collected from India Meteorological Department (IMD), Alipore, Kolkata; solar insolation obtained from Solar Geophysical Data Book and El-Niño index collected from National Climatic Data Center, US Department of Commerce, National Oceanic and Atmospheric Administration, USA. The effect of these climatic parameters and ozone precursors on ozone variations is critically analyzed and explained on the basis of linear regression and correlation. It has been observed that the maximum, minimum and mean temperature, relative humidity, solar insolation, tropospheric, and total ozone column (TOC) showed slight increasing tendencies from October 2004 to December 2011, while total rainfall and El-Niño index showed little decreasing tendencies for the same period. Amongst selected climatic parameters and ozone precursors, the solar insolation and the average temperature had a significant influence on both, the tropospheric ozone and total ozone column formation. The solar insolation had contributed more in tropospheric ozone than in total ozone column; while El-Niño index had played a more significant role in total ozone column build up than in tropospheric ozone. Negative correlation was observed between almost all ozone precursors with the tropospheric and total ozone. The tropospheric ozone and total ozone column were also significantly correlated. The level of significance and contribution of different climatic parameters are determined from correlation technique and Multiple Linear Regression (MLR) method

  5. VUV and soft x-ray ionization of a plant volatile: Vanillin (C8H8O3).

    PubMed

    Betancourt, A Moreno; Coutinho, L H; Bernini, R B; de Moura, C E V; Rocha, A B; de Souza, G G B

    2016-03-21

    Plant volatiles are emitted by plants in response to several forms of stress, including interaction with energetic photons. In the present work, we discuss the interaction of extreme UV and soft X-ray photons with a plant volatile, vanillin. The single and double (multiple) ionization of the vanillin molecule have been studied for the first time using time-of-flight mass spectrometry and VUV and soft X-ray photons (synchrotron radiation, at 12.0 eV, 21.2 eV, 130 eV, 310 eV, 531 eV, and 550 eV). At 12.0 and 21.2 eV, only singly charged species are observed and the parent ion, C8H8O3 (+), is the dominant species. Energy differences for some selected fragments were calculated theoretically in this energy region. At 130 eV, direct double and triple ionization of the valence electrons may occur. The fragmentation increases and CHO(+) becomes one of the main cations in the mass spectrum. The molecular ion is still the dominant species, but other fragments, such as C6H5O(+), begin to present similar intensities. At 310 eV, C 1s electrons may be ionized and Auger processes give rise to dissociative doubly ionized cations. Ionization around the O 1s edge has been studied both at the 531 eV resonance and above the ionization edge. Resonant and normal Auger processes play a significant role in each case and a large fragmentation of the molecule is observed at both photon energies, with intense fragments such as CHO(+) and CH3 (+) being clearly observed. A near edge X-ray absorption fine structure spectrum of the vanillin molecule was obtained around the O 1s ionization threshold. In addition, the fragmentation of vanillin has also been studied using a fast beam of electrons (800 eV), for the sake of comparison. PMID:27004874

  6. VUV and soft x-ray ionization of a plant volatile: Vanillin (C8H8O3)

    NASA Astrophysics Data System (ADS)

    Betancourt, A. Moreno; Coutinho, L. H.; Bernini, R. B.; de Moura, C. E. V.; Rocha, A. B.; de Souza, G. G. B.

    2016-03-01

    Plant volatiles are emitted by plants in response to several forms of stress, including interaction with energetic photons. In the present work, we discuss the interaction of extreme UV and soft X-ray photons with a plant volatile, vanillin. The single and double (multiple) ionization of the vanillin molecule have been studied for the first time using time-of-flight mass spectrometry and VUV and soft X-ray photons (synchrotron radiation, at 12.0 eV, 21.2 eV, 130 eV, 310 eV, 531 eV, and 550 eV). At 12.0 and 21.2 eV, only singly charged species are observed and the parent ion, C8H8O3+, is the dominant species. Energy differences for some selected fragments were calculated theoretically in this energy region. At 130 eV, direct double and triple ionization of the valence electrons may occur. The fragmentation increases and CHO+ becomes one of the main cations in the mass spectrum. The molecular ion is still the dominant species, but other fragments, such as C6H5O+, begin to present similar intensities. At 310 eV, C 1s electrons may be ionized and Auger processes give rise to dissociative doubly ionized cations. Ionization around the O 1s edge has been studied both at the 531 eV resonance and above the ionization edge. Resonant and normal Auger processes play a significant role in each case and a large fragmentation of the molecule is observed at both photon energies, with intense fragments such as CHO+ and CH3+ being clearly observed. A near edge X-ray absorption fine structure spectrum of the vanillin molecule was obtained around the O 1s ionization threshold. In addition, the fragmentation of vanillin has also been studied using a fast beam of electrons (800 eV), for the sake of comparison.

  7. Carbon-14 immobilization via the Ba(OH)/sub 2/. 8H/sub 2/O process

    SciTech Connect

    Haag, G.L.; Nehls, J.W. Jr.; Young, G.C.

    1983-03-01

    The airborne release of /sup 4/C from varous nuclear facilities has been identified as a potential biohazard due to the long half-life of /sup 14/C (5730 y) and the ease with which it may be assimilated into the biosphere. At ORNL, technology has been developed for the removal and immobilization of this radionuclide. Prior studies have indicated that /sup 14/C will likely exist in the oxidized form as CO/sub 2/ and will contribute slightly to the bulk CO/sub 2/ concentration of the gas stream, which is airlike in nature (approx. 330 ppmv CO/sub 2/). The technology that has been developed utilizes the CO/sub 2/-Ba(OH)/sub 2/.8H/sub 2/O gas-solid reaction with the mode of gas-solid contacting being a fixed bed. The product, BaCO/sub 3/, possesses excellent thermal and chemical stability, prerequisites for the long-term disposal of nuclear wastes. For optimal process operation, studies have indicated that an operating window of adequate size does exist. When operating within the window, high CO/sub 2/ removal efficiency (effluent concentrations < 100 ppbv), high reactant utilization (> 99%), and an acceptable pressure drop across the bed (3 kPa/m at a superficial velocity of 13 cm/s) are possible. This paper addresses three areas of experimental investigation: (1) microscale studies on 150-mg samples to provide information concerning surface properties, kinetics, and equilibrium vapor pressures; (2) macroscale studies on large fixed beds (4.2 kg of reactant) to determine the effects of humidity, temperature, and gas flow rate upon bed pressure drop and CO/sub 2/ breakthrough; and (3) design, construction, and initial operation of a pilot unit capable of continuously processing a 34-m/sup 3//h (20-ft/sup 3//min) air-based gas stream.

  8. A multi-sensor upper tropospheric ozone product (MUTOP) based on TES Ozone and GOES water vapor: derivation

    NASA Astrophysics Data System (ADS)

    Felker, S. R.; Moody, J. L.; Wimmers, A. J.; Osterman, G.; Bowman, K.

    2011-07-01

    The Tropospheric Emission Spectrometer (TES), a hyperspectral infrared instrument on the Aura satellite, retrieves a vertical profile of tropospheric ozone. However, polar-orbiting instruments like TES provide limited nadir-view coverage. This work illustrates the value of these observations when taken in context with geostationary imagery describing synoptic-scale weather patterns. The goal of this study is to create map-view products of upper troposphere (UT) ozone through the integration of TES ozone measurements with two synoptic dynamic tracers of stratospheric influence: specific humidity derived from the GOES Imager water vapor absorption channel, and potential vorticity (PV) from an operational forecast model. As a mixing zone between tropospheric and stratospheric reservoirs, the upper troposphere (UT) exhibits a complex chemical makeup. Determination of ozone mixing ratios in this layer is especially difficult without direct in situ measurement. However, it is well understood that UT ozone is correlated with dynamical tracers like low specific humidity and high potential vorticity. Blending the advantages of two remotely sensed quantities (GOES water vapor and TES ozone) is at the core of the Multi-sensor Upper Tropospheric Ozone Product (MUTOP). Our results suggest that 72 % of TES-observed UT ozone variability can be explained by its correlation with dry air and high PV. MUTOP reproduces TES retrievals across the GOES-West domain with a root mean square error (RMSE) of 18 ppbv (part per billion by volume). There are several advantages to this multi-sensor derived product approach: (1) it is calculated from two operational fields (GOES specific humidity and GFS PV), so maps of layer-average ozone can be created and used in near real-time; (2) the product provides the spatial resolution and coverage of a geostationary image as it depicts the variable distribution of ozone in the UT; and (3) the 6 h temporal resolution of the derived product imagery allows

  9. A New ENSO Index Derived from Satellite Measurements of Column Ozone

    NASA Technical Reports Server (NTRS)

    Ziemke, J. R.; Chandra, S.; Oman, L. D.; Bhartia, P. K.

    2010-01-01

    Column Ozone measured in tropical latitudes from Nimbus 7 total ozone mapping spectrometer (TOMS), Earth Probe TOMS, solar backscatter ultraviolet (SBUV), and Aura ozone monitoring instrument (OMI) are used to derive an El Nino-Southern Oscillation (ENSO) index. This index, which covers a time period from 1979 to the present, is defined as the Ozone ENSO Index (OEI) and is the first developed from atmospheric trace gas measurements. The OEI is constructed by first averaging monthly mean column ozone over two broad regions in the western and eastern Pacific and then taking their difference. This differencing yields a self-calibrating ENSO index which is independent of individual instrument calibration offsets and drifts in measurements over the long record. The combined Aura OMI and MLS ozone data confirm that zonal variability in total column ozone in the tropics caused by ENSO events lies almost entirely in the troposphere. As a result, the OEI can be derived directly from total column ozone instead of tropospheric column ozone. For clear-sky ozone measurements a +1K change in Nino 3.4 index corresponds to +2.9 Dobson Unit (DU) change in the OEI, while a +1 hPa change in SOI coincides with a -1.7DU change in the OEI. For ozone measurements under all cloud conditions these numbers are +2.4DU and -1.4 DU, respectively. As an ENSO index based upon ozone, it is potentially useful in evaluating climate models predicting long term changes in ozone and other trace gases.

  10. 16 CFR 260.11 - Ozone-safe and ozone-friendly claims.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... friendly to, the ozone layer or the atmosphere. Example 1: A product is labeled “ozone-friendly.” The claim... 16 Commercial Practices 1 2013-01-01 2013-01-01 false Ozone-safe and ozone-friendly claims. 260.11... THE USE OF ENVIRONMENTAL MARKETING CLAIMS § 260.11 Ozone-safe and ozone-friendly claims. It...

  11. 16 CFR 260.11 - Ozone-safe and ozone-friendly claims.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... friendly to, the ozone layer or the atmosphere. Example 1: A product is labeled “ozone-friendly.” The claim... 16 Commercial Practices 1 2014-01-01 2014-01-01 false Ozone-safe and ozone-friendly claims. 260.11... THE USE OF ENVIRONMENTAL MARKETING CLAIMS § 260.11 Ozone-safe and ozone-friendly claims. It...

  12. Sensitivity of the FVGCM to Changes in Ozone

    NASA Technical Reports Server (NTRS)

    Stolarski; Pawson, S.; Nielsen, J. Eric; Douglass, A.; Newman, P.

    2004-01-01

    We have carried out an experiment with the finite volume general circulation model (FVGCM). This experiment consisted of two different imposed changes in the climatological ozone fields assumed in the radiation code. for conditions with no significant ozone hole. This distribution was obtained from a 50-year simulation of the full stratospheric ozone chemistry, with a time-dependent chlorine loading, done with our off-line chemical transport model (CTM). Three years (1978-1980) of this simulation were averaged to form a monthly, zonal-mean ozone distribution that was used in the 20-year integration of the FVGCM for "unperturbed" conditions. The second 20-year GCM integration included a fully-developed ozone hole. This ozone distribution was from three years, 1998-2000, from the same CTM simulation. The goal of this work is to determine the coupled response of the chemistry and dynamics of the stratosphere. These experiments are the first step in understanding the coupled response. An important initial question concerns the significance of the signals: if 20-year integrations turn out to be too short, the runs will be extended.

  13. Estimate of ozone production and destruction over northwestern Europe

    NASA Astrophysics Data System (ADS)

    Beck, Jeannette P.; Grennfelt, Peringe

    Ozone data from more than 70 monitoring sites in the European TOR and EMEP networks from 1989 were evaluated. In summer the general spatial pattern showed a gradient in the average diurnal maximum ozone concentration with lower values (30-40 ppb) in the northwestern part and higher concentrations (60-70 ppb) towards the southeastern part of the networks. In winter a decreasing gradient was exhibited from the northwest to the southeast. The current UN-ECE 1-h guide value (75 ppb) for the prevention of vegetation damage was exceeded regularly at nearly all sites; the provisional O 3 exposure limit of 300 ppb.h (product of the residual ozone concentration above a threshold (40 ppb) value and exposure duration) was exceeded at all monitoring sites. An estimate of the European internal production and destruction of ozone was made by analyzing the diurnal variation in ozone at European boundary layer background "reference" sites and "polluted" sites. The assessment led to a summer mean internal production of 10-15 ppb in some areas in central Europe, while during winter an ozone sink was found. A complicating factor in this work proved to be the degree of influence of local factors, e.g. emission of oxides of nitrogen and dry deposition. This study therefore emphasizes the importance of spatial characterization of the monitoring sites.

  14. On the size of the Antarctic ozone hole

    NASA Astrophysics Data System (ADS)

    Newman, Paul A.; Kawa, S. Randolph; Nash, Eric R.

    2004-11-01

    A primary estimate of the severity of the Antarctic ozone hole is its size. The size is calculated from the area contained by total column ozone values less than 220 Dobson Units (DU) during September-October. The 220-DU value is used because it is lower than pre-1980 observed ozone values, and because it is in the strong ozone gradient region. We quantitatively show that the ozone hole size is primarily sensitive to effective stratospheric chlorine trends, and secondarily to the year-to-year variations in temperatures near the edge of the polar vortex. Temperatures are in turn sensitive to variations in tropospheric planetary wave forcing of the Southern Hemisphere stratosphere. Currently the average hole size reaches approximately 25 million km2 each spring. Slow decreases of ozone depleting substances will only result in a decrease of about 1 million km2 by 2015. This slow size decrease will be obscured by large dynamically forced year-to-year variations of 4 million km2 (1σ), and possibly delayed by greenhouse gas cooling of the Antarctic stratosphere.

  15. CFCS and the ozone layer.

    PubMed

    Hayman, G D

    1997-05-01

    Ozone is an important constituent of the atmosphere. Ozone forms a distinct layer in the lower stratosphere known as the ozone layer. The ozone layer acts as a fragile shield because it protects man and other life forms from exposure to harmful short-wavelength ultraviolet (UV) radiation. The agents, particularly chemical, which affect the amount of ozone present in the atmosphere have been a source of concern for more than 20 years. This has been reinforced by the dramatic decline of stratospheric ozone levels first measured in Antarctica and now apparent worldwide. The combination of routine measurements of ozone depletion, careful laboratory studies and mathematical modelling of ozone in the atmosphere, has demonstrated that the reactive fragments produced when chlorofluorocarbons (CFCs), halons and other halogenated compounds break down in the stratosphere are responsible for the ozone loss. As CFCs have widespread and sometimes apparently essential uses in modern society, there has been an intense effort to develop safe, effective replacements which have a negligible or much smaller impact on the environment. The Montreal Protocol, signed by over 140 nations, has been implemented to control and phase out the chemical compounds responsible for ozone loss. PMID:9519506

  16. Precision ozone calibration system based on vapor pressures of ozone

    NASA Technical Reports Server (NTRS)

    Mauersberger, K.; Hanson, D.; Morton, J.

    1987-01-01

    A precision ozone calibration system for stratospheric research has been developed and evaluated. Vapor pressures above solid ozone are mixed with a carrier gas (N2) to produce stratospheric ozone mixing ratios at total pressures of 1 to cover 20 torr. The uncertainty in the ozone mixing ratios is approximately + or - 1.5 percent, the stability of ozone is + or - 0.3 percent. Experiments to be calibrated may sample the gas mixture over a wide range of flow rates; the maximum throughput of gas with corrections of less than 1 percent to ozone is about 200 torr 1/min. A mass spectrometer system continuously monitors the purity and stability of the N2-O3 gas mixture.

  17. Probabilistic aspects of meteorological and ozone regional ensemble forecasts

    SciTech Connect

    Monache, L D; Hacker, J; Zhou, Y; Deng, X; Stull, R

    2006-03-20

    This study investigates whether probabilistic ozone forecasts from an ensemble can be made with skill; i.e., high verification resolution and reliability. Twenty-eight ozone forecasts were generated over the Lower Fraser Valley, British Columbia, Canada, for the 5-day period 11-15 August 2004, and compared with 1-hour averaged measurements of ozone concentrations at five stations. The forecasts were obtained by driving the CMAQ model with four meteorological forecasts and seven emission scenarios: a control run, {+-} 50% NO{sub x}, {+-} 50% VOC, and {+-} 50% NO{sub x} combined with VOC. Probabilistic forecast quality is verified using relative operating characteristic curves, Talagrand diagrams, and a new reliability index. Results show that both meteorology and emission perturbations are needed to have a skillful probabilistic forecast system--the meteorology perturbation is important to capture the ozone temporal and spatial distribution, and the emission perturbation is needed to span the range of ozone-concentration magnitudes. Emission perturbations are more important than meteorology perturbations for capturing the likelihood of high ozone concentrations. Perturbations involving NO{sub x} resulted in a more skillful probabilistic forecast for the episode analyzed, and therefore the 50% perturbation values appears to span much of the emission uncertainty for this case. All of the ensembles analyzed show a high ozone concentration bias in the Talagrand diagrams, even when the biases from the unperturbed emissions forecasts are removed from all ensemble members. This result indicates nonlinearity in the ensemble, which arises from both ozone chemistry and its interaction with input from particular meteorological models.

  18. Intercomparison of stratospheric ozone profiles for the assessment of the upgraded GROMOS radiometer at Bern

    NASA Astrophysics Data System (ADS)

    Studer, S.; Hocke, K.; Pastel, M.; Godin-Beekmann, S.; Kämpfer, N.

    2013-07-01

    Since November 1994, the GROund-based Millimeter-wave Ozone Spectrometer (GROMOS) measures stratospheric and lower mesospheric ozone in Bern, Switzerland (47.95° N, 7.44° E). GROMOS is part of the Network for the Detection of Atmospheric Composition Change (NDACC). In July 2009, a Fast-Fourier-Transform spectrometer (FFTS) has been added as backend to GROMOS. The new FFTS and the original filter bench (FB) measured parallel for over two years. In October 2011, the FB has been turned off and the FFTS is now used to continue the ozone time series. For a consolidated ozone time series in the frame of NDACC, the quality of the stratospheric ozone profiles obtained with the FFTS has to be assessed. The FFTS results from July 2009 to December 2011 are compared to ozone profiles retrieved by the FB. FFTS and FB of the GROMOS microwave radiometer agree within 5% above 20 hPa. A later harmonization of both time series will be realized by taking the FFTS as benchmark for the FB. Ozone profiles from the FFTS are also compared to coinciding lidar measurements from the Observatoire Haute Provence (OHP), France. For the time period studied a maximum mean difference (lidar - GROMOS FFTS) of +3.8% at 3.1 hPa and a minimum mean difference of +1.4% at 8 hPa is found. Further, intercomparisons with ozone profiles from other independent instruments are performed: satellite measurements include MIPAS onboard ENVISAT, SABER onboard TIMED, MLS onboard EOS Aura and ACE-FTS onboard SCISAT-1. Additionally, ozonesondes launched from Payerne, Switzerland, are used in the lower stratosphere. Mean relative differences of GROMOS FFTS and these independent instruments are less than 10% between 50 and 0.1 hPa.

  19. Fundamental differences between Arctic and Antarctic ozone depletion.

    PubMed

    Solomon, Susan; Haskins, Jessica; Ivy, Diane J; Min, Flora

    2014-04-29

    Antarctic ozone depletion is associated with enhanced chlorine from anthropogenic chlorofluorocarbons and heterogeneous chemistry under cold conditions. The deep Antarctic "hole" contrasts with the generally weaker depletions observed in the warmer Arctic. An unusually cold Arctic stratospheric season occurred in 2011, raising the question of how the Arctic ozone chemistry in that year compares with others. We show that the averaged depletions near 20 km across the cold part of each pole are deeper in Antarctica than in the Arctic for all years, although 2011 Arctic values do rival those seen in less-depleted years in Antarctica. We focus not only on averages but also on extremes, to address whether or not Arctic ozone depletion can be as extreme as that observed in the Antarctic. This information provides unique insights into the contrasts between Arctic and Antarctic ozone chemistry. We show that extreme Antarctic ozone minima fall to or below 0.1 parts per million by volume (ppmv) at 18 and 20 km (about 70 and 50 mbar) whereas the lowest Arctic ozone values are about 0.5 ppmv at these altitudes. At a higher altitude of 24 km (30-mbar level), no Arctic data below about 2 ppmv have been observed, including in 2011, in contrast to values more than an order of magnitude lower in Antarctica. The data show that the lowest ozone values are associated with temperatures below -80 °C to -85 °C depending upon altitude, and are closely associated with reduced gaseous nitric acid concentrations due to uptake and/or sedimentation in polar stratospheric cloud particles. PMID:24733920

  20. Fundamental differences between Arctic and Antarctic ozone depletion

    PubMed Central

    Solomon, Susan; Haskins, Jessica; Ivy, Diane J.; Min, Flora

    2014-01-01

    Antarctic ozone depletion is associated with enhanced chlorine from anthropogenic chlorofluorocarbons and heterogeneous chemistry under cold conditions. The deep Antarctic “hole” contrasts with the generally weaker depletions observed in the warmer Arctic. An unusually cold Arctic stratospheric season occurred in 2011, raising the question of how the Arctic ozone chemistry in that year compares with others. We show that the averaged depletions near 20 km across the cold part of each pole are deeper in Antarctica than in the Arctic for all years, although 2011 Arctic values do rival those seen in less-depleted years in Antarctica. We focus not only on averages but also on extremes, to address whether or not Arctic ozone depletion can be as extreme as that observed in the Antarctic. This information provides unique insights into the contrasts between Arctic and Antarctic ozone chemistry. We show that extreme Antarctic ozone minima fall to or below 0.1 parts per million by volume (ppmv) at 18 and 20 km (about 70 and 50 mbar) whereas the lowest Arctic ozone values are about 0.5 ppmv at these altitudes. At a higher altitude of 24 km (30-mbar level), no Arctic data below about 2 ppmv have been observed, including in 2011, in contrast to values more than an order of magnitude lower in Antarctica. The data show that the lowest ozone values are associated with temperatures below −80 °C to −85 °C depending upon altitude, and are closely associated with reduced gaseous nitric acid concentrations due to uptake and/or sedimentation in polar stratospheric cloud particles. PMID:24733920

  1. Analysis of the effects of combustion emissions and Santa Ana winds on ambient ozone during the October 2007 southern California wildfires

    NASA Astrophysics Data System (ADS)

    Bytnerowicz, Andrzej; Cayan, Dan; Riggan, Philip; Schilling, Susan; Dawson, Philip; Tyree, Mary; Wolden, Lynn; Tissell, Robert; Preisler, Haiganoush

    2010-02-01

    Combustion emissions and strong Santa Ana winds had pronounced effects on patterns and levels of ambient ozone (O 3) in southern California during the extensive wildland fires of October 2007. These changes are described in detail for a rural receptor site, the Santa Margarita Ecological Reserve, located among large fires in San Diego and Orange counties. In addition, O 3 changes are also described for several other air quality monitoring sites in the general area of the fires. During the first phase of the fires, strong, dry and hot northeasterly Santa Ana winds brought into the area clean continental air masses, which resulted in minimal diurnal O 3 fluctuations and a 72-h average concentration of 36.8 ppb. During the second phase of the fires, without Santa Ana winds present and air filled with smoke, daytime O 3 concentrations steadily increased and reached 95.2 ppb while the lowest nighttime levels returned to ˜0 ppb. During that period the 8-h daytime average O 3 concentration reached 78.3 ppb, which exceeded the federal standard of 75 ppb. After six days of fires, O 3 diurnal concentrations returned to pre-fire patterns and levels.

  2. Balloonborne ozone and aerosol measurements in the antarctic ozone hole

    SciTech Connect

    Hofmann, D.J.; Harder, J.W.; Rolf, S.R.; Rosen, J.M. )

    1987-01-01

    The National Ozone Expedition (NOZE) was mounted in 1986 using winter fly-in flights to McMurdo Station in August, which is approximately the time the ozone reduction begins. The University of Wyoming Atmospheric Physics group participated in this expedition through balloonborne measurements of the vertical distribution of ozone and aerosol particles. Between 24 August and 6 November, 33 ozone soundings, 6 aerosol sounding, and 3 condensation nuclei soundings were conducted using polyethylene balloons which were able to penetrate the cold (< {minus}80C) antarctic stratosphere. The authors summarize these results here.

  3. Ozone and ozone byproducts in the cabins of commercial aircraft.

    PubMed

    Weisel, Clifford; Weschler, Charles J; Mohan, Kris; Vallarino, Jose; Spengler, John D

    2013-05-01

    The aircraft cabin represents a unique indoor environment due to its high surface-to-volume ratio, high occupant density, and the potential for high ozone concentrations at cruising altitudes. Ozone was continuously measured and air was sampled on sorbent traps, targeting carbonyl compounds, on 52 transcontinental U.S. or international flights between 2008 and 2010. The sampling was predominantly on planes that did not have ozone scrubbers (catalytic converters). Peak ozone levels on aircraft without catalytic convertors exceeded 100 ppb, with some flights having periods of more than an hour when the ozone levels were >75 ppb. Ozone was greatly reduced on relatively new aircraft with catalytic convertors, but ozone levels on two flights whose aircraft had older convertors were similar to those on planes without catalytic convertors. Hexanal, heptanal, octanal, nonanal, decanal, and 6-methyl-5-hepten-2-one (6-MHO) were detected in the aircraft cabin at sub- to low ppb levels. Linear regression models that included the log transformed mean ozone concentration, percent occupancy, and plane type were statistically significant and explained between 18 and 25% of the variance in the mixing ratio of these carbonyls. Occupancy was also a significant factor for 6-MHO, but not the linear aldehydes, consistent with 6-MHO's formation from the reaction between ozone and squalene, which is present in human skin oils. PMID:23517299

  4. A study of interferences in ambient ozone monitors

    SciTech Connect

    Kleindienst, T.E.; McIver, C.D.; Ollison, W.M.

    1997-12-31

    Recently proposed EPA revisions to the ozone ambient air quality standards change allowable ozone levels from 120 ppbv (1-hour average) to 70-90 ppbv (8-hour average). Accordingly, the relative importance of potential interferences in currently deployed ethylene-chemiluminescence and ultraviolet (UV) absorption monitors may be increased. UV absorption monitors predominate US monitoring networks and operate in a dual channel mode, requiring a scrubber to selectively remove ozone from other UV absorbing species. However, these scrubbers may also remove aromatic species with UV absorption coefficients at 254 run comparable to ozone that could constitute potential interferants. The interference potential for only a few of these compounds has been determined. Additional representative organic precursor species likely to be present under polluted conditions (e.g., C{sub 8}-C{sub 9} aromatic hydrocarbons and their nitroaromatic and phenolic derivatives) have been tested as UV interferants in this study. The removal and reentrainment of aromatic pollutants on ozone scrubbers used in UV monitors is highly dependent on the relative humidity in the system. Raising the temperature of the scrubber does not improve its interferant transmission under dry conditions and increases the retention of potential interferants under humid conditions. Reduced sulfur compounds such as CS{sub 2} do not appear to be interferants for the chemiluminescence monitor.

  5. Bias in Dobson total ozone measurements at high latitudes due to approximations in calculations of ozone absorption coefficients and air mass

    NASA Astrophysics Data System (ADS)

    Bernhard, G.; Evans, R. D.; Labow, G. J.; Oltmans, S. J.

    2005-05-01

    80°. When Dobson measurements are corrected for the temperature dependence of the ozone absorption cross section and accurate air mass calculations are implemented, data from the three instruments agree with each other to within ±2% on average and show no significant dependence on SZA or total ozone.

  6. Microemulsion-assisted solvothermal synthesis of Nd{sub 2}(CO{sub 3}){sub 3}.8H{sub 2}O microstructures

    SciTech Connect

    Zhu, Wenqing; Ma, Jin; Xing, Xiping; Xu, Lei; Chen, Yashao

    2011-06-15

    Research highlights: {yields} Pyramid-like and spherical Nd{sub 2}(CO{sub 3}){sub 3}.8H{sub 2}O microstructures were synthesized using a microemulsion-assisted solvothermal method with precise control of the reaction time and reaction temperature. {yields} The obtained products were characterized by X-ray diffraction (XRD), differential scanning calorimetry and thermal gravimetric analysis (DSC-TGA), scanning electron microscope (SEM), transmission electron microscope (TEM) and electron diffraction (ED). {yields} The increase in size of pyramid-like Nd{sub 2}(CO{sub 3}){sub 3}.8H{sub 2}O microstructures with increasing reaction time was attributed to the typical Ostwald ripening process, while the increase in size of spherical Nd{sub 2}(CO{sub 3}){sub 3}.8H{sub 2}O microstructures with increasing reaction temperature was explained by the increasing collision probability of microemulsion droplets. -- Abstract: Microstructures of Nd{sub 2}(CO{sub 3}){sub 3}.8H{sub 2}O with various morphological structures and sizes were successfully synthesized using the microemulsion-assisted solvothermal method. The obtained products were characterized by X-ray diffraction (XRD), differential scanning calorimetry and thermal gravimetric analysis (DSC-TGA), scanning electron microscope (SEM), transmission electron microscope (TEM) and electron diffraction (ED). The results showed that pyramid-like and spherical Nd{sub 2}(CO{sub 3}){sub 3}.8H{sub 2}O microstructures were synthesized depending on the reaction time and reaction temperature. Moreover, the reaction time and temperature also played important roles in controlling the morphologies and sizes of the resulting Nd{sub 2}(CO{sub 3}){sub 3}.8H{sub 2}O microstructures.

  7. Carbon-14 immobilization via the Ba(OH)/sub 2/8H/sub 2/O process

    SciTech Connect

    Haag, G.L.; Nehls, J.W. Jr.; Young, G.C.

    1982-01-01

    The airborne release of /sup 14/C from various nuclear facilities has been identified as a potential biohazard due to the long half-life of /sup 14/C (5730 yrs) and the ease in which it may be assimilated into the biosphere. At Oak Ridge National Laboratory, technology is under development, as part of the Airborne Waste Management Program, for the removal and immobilization of this radionuclide. Prior studies have indicated that the /sup 14/C will likely exist in the oxidized form as CO/sub 2/ and will contribute slightly to the bulk CO/sub 2/ concentration of the gas stream, which is airlike in nature (approx. 330 ppMv CO/sub 2/). The technology under development utilizes the CO/sub 2/ - Ba(OH)/sub 2/ 8H/sub 2/O gas-solid reaction with the mode of gas-solid contacting being a fixed bed. The product, BaCO/sub 3/, possessing excellent thermal and chemical stability, prerequisites for the long-term disposal of nuclear wastes. For optimal process operation, studies have indicated that an operating window of adequate size does exist. When operating within the window, high CO/sub 2/ removal efficiency (effluent concentrations < 100 ppBv), high reactant utilization (> 99%), and an acceptable pressure drop across the bed (3 kPa/m at 13 cm/s superficial velocity) are possible. This paper will address three areas of experimental investigation. These areas are (1) micro-scale studies on 150-mg samples to provide information concerning surface properties, kinetics, and equilibrium vapor pressures, (2) macro-scale studies on large fixed beds (4.2 kg reactant) to determine the effects of humidity, temperature, and gas flow-rate upon bed pressure drop and CO/sub 2/ breakthrough, and (3) the design, construction, and initial operation of a pilot unit capable of continuously processing a 34 m/sup 3//h (20 ft/sup 3//min) air-based gas stream.

  8. Ozone Risk Assessment Utilities

    1999-08-10

    ORAMUS is a user-friendly, menu-driven software system that calculates and displays user-selected risk estimates for health effects attributable to short-term exposure to tropospheric ozone. Inputs to the risk assessment are estimates of exposure to ozone and exposure-response relationships to produce overall risk estimates in the form of probability distributions. Three fundamental models are included: headcount risk, benchmark risk, and hospital admissions. Exposure-response relationships are based on results of controlled human exposure studies. Exposure estimates aremore » based on the EPA''s probabilistic national ambient air quality standards (NAAQS) exposure model, pNEM/Osub3, which simulates air quality associated with attainment of alternative NAAQS. Using ORAMUS, risk results for 27 air quality scenarios, air quality in 9 urban areas, 33 health endpoints, and 4 chronic health endpoints can be calculated.« less

  9. The Antarctic ozone hole

    SciTech Connect

    Stolarski, R.S.

    1988-01-01

    Because the effects are so serious, many investigators have been racing to determine the causes of the hole which develops each southern spring within the polar vortex, an isolated air mass that circulates around the South Pole during a large part of the year. This paper reviews two of the foremost theories for this ozone hole. Mechanisms of the pollution theory, which proposes that the cause is chlorofluorocarbons and nitrogen oxides in the atmosphere, are reviewed. The second theory proposes a natural shift in the air movements that transport ozone-rich air into the polar stratosphere during the southern spring as the cause. Current data suggest both theories are correct, but data are considered inconclusive.

  10. Ozonated olive oils and the troubles.

    PubMed

    Uysal, Bulent

    2014-01-01

    One of the commonly used methods for ozone therapy is ozonated oils. Most prominent type of used oils is extra virgin olive oil. But still, each type of unsaturated oils may be used for ozonation. There are a lot of wrong knowledge on the internet about ozonated oils and its use as well. Just like other ozone therapy studies, also the studies about ozone oils are inadequate to avoid incorrect knowledge. Current data about ozone oil and its benefits are produced by supplier who oversees financial interests and make misinformation. Despite the rapidly increasing ozone oil sales through the internet, its quality and efficacy is still controversial. Dozens of companies and web sites may be easily found to buy ozonated oil. But, very few of these products are reliable, and contain sufficiently ozonated oil. This article aimed to introduce the troubles about ozonated oils and so to inform ozonated oil users. PMID:26401346

  11. Ozone, Air Quality, and Asthma (For Parents)

    MedlinePlus

    ... found in both the Earth's upper and lower atmospheres. The protective ozone in the upper atmosphere is very different from the harmful ozone in the lower atmosphere. Ozone that exists naturally 10 to 30 miles ( ...

  12. Ozonated olive oils and the troubles

    PubMed Central

    Uysal, Bulent

    2014-01-01

    One of the commonly used methods for ozone therapy is ozonated oils. Most prominent type of used oils is extra virgin olive oil. But still, each type of unsaturated oils may be used for ozonation. There are a lot of wrong knowledge on the internet about ozonated oils and its use as well. Just like other ozone therapy studies, also the studies about ozone oils are inadequate to avoid incorrect knowledge. Current data about ozone oil and its benefits are produced by supplier who oversees financial interests and make misinformation. Despite the rapidly increasing ozone oil sales through the internet, its quality and efficacy is still controversial. Dozens of companies and web sites may be easily found to buy ozonated oil. But, very few of these products are reliable, and contain sufficiently ozonated oil. This article aimed to introduce the troubles about ozonated oils and so to inform ozonated oil users. PMID:26401346

  13. Ozone Air Quality Impacts of Shale Gas Development in South Texas Urban Areas

    NASA Astrophysics Data System (ADS)

    Chang, C.; Liao, K.

    2013-12-01

    Recent technological advances, mainly horizontal drilling and hydraulic fracturing, and continued drilling in shale, have increased domestic production of oil and gas in the United State (U.S.). However, shale gas developments could also affect the environment and human health, particularly in areas where oil and gas developments are new activities. This study is focused on the impacts of shale gas developing activities on summertime ozone air quality in South Texas urban areas since many of them are already ozone nonattainment areas. We use an integrated approach to investigate the ozone air quality impact of the shale gas development in South Texas urban areas. They are: (1) satellite measurement of precursors, (2) observations of ground-level ozone concentrations, and (3) air mass trajectory modeling. Nitrogen dioxide (NO2) is an important precursor to ozone formation, and summertime average tropospheric nitrogen dioxide (NO2) column densities measured by the National Aeronautics and Space Administration's Ozone Monitoring Instrument increased in the South Texas shale area (i.e., the Eagle Ford Shale area) in 2011 and 2012 as compared to 2008-2010. The U.S. Environmental Protection Agency's ground-level observations showed summertime average and peak ozone (i.e., the 4th highest daily maximum 8-hour average ozone) concentrations slightly increased from 2010 to 2012 in Austin and San Antonio. However, the frequencies of peak ozone concentrations above the 75ppb ozone standard have been significantly increasing since 2011 in Austin and San Antonio. It is expected to increase the possibilities of violating the ozone National Ambient Air Quality Standard (NAAQS) for South Texas urban areas in the future. The results of trajectory modeling showed air masses transported from the southeastern Texas could reach Austin and San Antonio and confirmed that emissions from the Eagle Ford Shale area could affect ozone air quality in South Texas urban areas in 2011 and 2012

  14. Coherence of longterm stratospheric ozone time series for the study of ozone recovery in the northern mid-latitudes

    NASA Astrophysics Data System (ADS)

    Nair, Prijitha J.; Godin-Beekmann, Sophie; Pazmino, Andrea

    2010-05-01

    Since mid-to late 1980s decreasing amounts of ozone concentration has been observed in northern mid-latitudes mainly due to the ozone depleting chlorofluorocarbon loading in the stratosphere. Recent works indicate the stabilization of ozone loss in the mid-latitudes, in the upper stratosphere in particular. In order to further investigate the evolution of ozone in the mid-latitudes, a coherent dataset is required. As a first step, we diagnose the long term evolution of ozone at Observatoire de Haute Provence (OHP - 43.93°N, 5.71°E), one of the northern mid-latitude stations. In this study, we present the inter comparison of ozone measurements from OHP LIDAR with collocated SBUV, SAGEII, HALOE, MLS and GOMOS satellite observations as well as the ground based Ozonesondes and Umkehr measurements. A detailed statistical study on the relative differences of the compared measurements is performed to check any specific drifts with time. In addition, the seasonal and annual averages of the relative deviations are also checked to quantify agreement among the data. On average, all instruments show their best agreement with LIDAR between 20 and 40 km, where the differences are within 5%. The agreement with SAGEII measurements are remarkably good since it falls within 1% at 17-41 km. A similar result is also found from the Ozonesondes comparison at 22-31 km. Most comparisons exhibit slightly larger deviations below 20 and above 42 km, of about 10%. The LIDAR masurements are also compared to Umkehr measurements by converting its ozone number density to Dobson units for each Umkehr layer. The analysis reveals a negative bias in Umkehr data within -10% except at layer 6 (around 30 km).

  15. Improvements in total column ozone in GEOSCCM and comparisons with a new ozone-depleting substances scenario

    NASA Astrophysics Data System (ADS)

    Oman, Luke D.; Douglass, Anne R.

    2014-05-01

    The evolution of ozone is examined in the latest version of the Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM) using old and new ozone-depleting substances (ODS) scenarios. This version of GEOSCCM includes a representation of the quasi-biennial oscillation, a more realistic implementation of ozone chemistry at high solar zenith angles, an improved air/sea roughness parameterization, and an extra 5 parts per trillion of CH3Br to account for brominated very short-lived substances. Together these additions improve the representation of ozone compared to observations. This improved version of GEOSCCM was used to simulate the ozone evolution for the A1 2010 and the new Stratosphere-troposphere Processes and their Role in Climate (SPARC) 2013 ODS scenario derived using the SPARC Lifetimes Report 2013. This new ODS scenario results in a maximum Cltot increase of 65 parts per trillion by volume (pptv), decreasing slightly to 60 pptv by 2100. Approximately 72% of the increase is due to the longer lifetime of CFC-11. The quasi-global (60°S-60°N) total column ozone difference is relatively small and less than 1 Dobson unit on average and consistent with the 3-4% larger 2050-2080 average Cly in the new SPARC 2013 scenario. Over high latitudes, this small change in Cly compared to the relatively large natural variability makes it not possible to discern a significant impact on ozone in the second half of the 21st century in a single set of simulations.

  16. Improvements in Total Column Ozone in GEOSCCM and Comparisons with a New Ozone-Depleting Substances Scenario

    NASA Technical Reports Server (NTRS)

    Oman, Luke D.; Douglass, Anne R.

    2014-01-01

    The evolution of ozone is examined in the latest version of the Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM) using old and new ozone-depleting substances (ODS) scenarios. This version of GEOSCCM includes a representation of the quasi-biennial oscillation, a more realistic implementation of ozone chemistry at high solar zenith angles, an improved air/sea roughness parameterization, and an extra 5 parts per trillion of CH3Br to account for brominated very short-lived substances. Together these additions improve the representation of ozone compared to observations. This improved version of GEOSCCM was used to simulate the ozone evolution for the A1 2010 and the newStratosphere-troposphere Processes and their Role in Climate (SPARC) 2013 ODS scenario derived using the SPARC Lifetimes Report 2013. This new ODS scenario results in a maximum Cltot increase of 65 parts per trillion by volume (pptv), decreasing slightly to 60 pptv by 2100. Approximately 72% of the increase is due to the longer lifetime of CFC-11. The quasi-global (60degS-60degN) total column ozone difference is relatively small and less than 1Dobson unit on average and consistent with the 3-4% larger 2050-2080 average Cly in the new SPARC 2013 scenario. Over high latitudes, this small change in Cly compared to the relatively large natural variabilitymakes it not possible to discern a significant impact on ozone in the second half of the 21st century in a single set of simulations.

  17. Assessment of SAGE Version 6.1 Ozone Data Quality

    NASA Technical Reports Server (NTRS)

    Wang, Hsiang J.; Cunnold, Derek M.; Thomason, Larry W.; Zawodny, Joseph M.; Bodeker, Greg E.

    2002-01-01

    The SAGE-II V6.1 ozone retrievals are shown to be of better precision at all levels and to be much more accurate than previous retrievals in the lower stratosphere below 20 km altitude. A filtering procedure for removing anomalous ozone profiles associated with volcanic aerosol/cloud effects and other identified artifacts in V6.1 ozone is described. The agreement between SAGE and ozonesondes in the mean is shown to be approximately 10% down to the tropopause. Relative to the sondes SAGE tends to slightly overestimate ozone (less than 5%) between 15 and 20 km altitude, and systematically underestimates ozone in the troposphere by approximately 30% in the regions between 8 km altitude and 2 km below the tropopause. The precisions (random errors) of SAGE ozone retrievals above 25 km altitude are estimated to be 4% or better; they are a factor of ten worse below 16 km altitude. Linear trends in the differences between coincident SAGE and ozonesondes measurement are generally less than 0.3 %/year and not significantly different from zero in 95% confidence intervals. Compared to V5.96 retrievals, ozone trend differences between 20 and 50 km altitude are approximately 0. 1 %/year, below 20 km altitude the SAGE II trends are more positive by approximately 0.2 %/year. For the 1984-1999 period the SAGE-II shows a localized ozone loss of -0.4(+/- 0.25) %/year (2gigma) in the tropics at 20 km altitude. In the lower stratosphere between 16 and 22 km altitudes, the SAGE shows significant ozone losses in the mid-latitudes in both Hemispheres during the 1979-1999 periods. The ozone trends range from -0.24(+/- 0.18) to -0.77(+/- 0.46) (2sigma)%/year. However in the 1984-1999 period, the downward trends are smaller (-0.07 to - 0.25 %/year) in this altitude range, and the trends in the integrated column from 12 to 17 km altitude in mid-latitudes (35 deg - 60 deg) are not significantly different from zero (0.1 +?- 0.6 (2sigma)%/year). Averaged over the tropics (20 deg S to 20 deg N

  18. Ozone attainment: A different perspective

    SciTech Connect

    Beck, W.B. )

    1988-01-01

    Recent attention on the ozone non-attainment issue has been focused on Washington. Both Congress and the EPA have made efforts at addressing the post-1987 crisis in the many non-attainment areas. In contrast to the political activity, this paper presents some interesting technical perspectives on ozone attainment for many areas of the U.S.. Issues such as transport, climate and natural ozone sources are discussed in the context of exceedance frequency for several geographical areas of the country.

  19. Another deep Antarctic ozone hole

    SciTech Connect

    Kerr, R.A.

    1990-10-19

    Again in 1990, drastic depletion of stratospheric ozone over the South Pole has been measured, in August 140 Dobson units, far below the 220 Dobson units typically seen over Antarctica. This extensive destruction of ozone is determined to be brought about by sunshine acting in combination with the chlorine released from chlorofluorohydrocarbons (CFCs) by icy stratospheric clouds. It is concluded that CFC concentrations have now reached a level that will almost totally destroy the ozone in the lower stratosphere in most years.

  20. Ozone transport commission developments

    SciTech Connect

    Joyce, K.M.

    1995-08-01

    On September 27, 1994, the states of the Ozone Transport Commission (OTC) signed an important memorandum of understanding (MOU) agreeing to develop a regional strategy for controlling stationary sources of nitrogen oxide emissions. Specifically, the states of the Ozone Transport Region, OTR, agreed to propose regulations for the control of NOx emissions from boilers and other indirect heat exchangers with a maximum gross heat input rate of at least 250 million BTU per hour. The Ozone Transport Region was divided into Inner, Outer and Northern Zones. States in the Outer Zone agreed to reduce NOx emissions by 55%. States in the Inner Zone agreed to reduce NOx emissions 65%. Facilities in both zones have the option to emit NOx at a rate no greater than 0.2 pounds per million Btu by May 1, 1999. This option provides fairness for the gas-fired plants which already have relatively low NOx emissions. Additionally, States in the Inner and Outer Zones agreed to reduce their NOx emissions by 75% or to emit NOx at a rate no greater than 0.15 pounds per million BTU by May 1, 2003. The Northern Zone States agree to reduce their rate of NOx emissions by 55% from base year levels by May 1, 2003, or to emit NOx at a rate no greater than 0.2 pounds per million BTU. As part of this MOU, States also agreed to develop a regionwide trading mechanism to provide a cost-effective mechanism for implementing the reductions.

  1. Ozone-temperature relationships in the stratosphere

    NASA Technical Reports Server (NTRS)

    Miller, A. J.; Nagatani, R. M.; Frederick, J. E.

    1985-01-01

    Utilizing independent estimates of ozone and temperature fields from the SBUV (Nimbus 7) and NOAA operational satellites, respectively, for the period 1978-1981, the coefficient of variation between the two parameters is determined. This coefficient is defined as A = Delta-O3 x (T)/Delta T x (O3) wehre Delta is an incremental change in either temperature or ozone and the bracket is a mean state. In practice, A is determined on a daily basis by regression of ozone mixing ratio versus temperature around a latitude circle during the winter season and the bracket value is the daily zonal average. This has the advantage of keeping the solar zenith angle fixed for a daily value while allowing it to change during the season. This is done at 30, 10, 5, 2, and 1 mb from 20 deg to 60 deg latitude in both hemispheres. The results are summarized and compared with those determined from a one-dimensional photochemical model applied to different latitudes.

  2. Ozone measurement systems improvements studies

    NASA Technical Reports Server (NTRS)

    Thomas, R. W.; Guard, K.; Holland, A. C.; Spurling, J. F.

    1974-01-01

    Results are summarized of an initial study of techniques for measuring atmospheric ozone, carried out as the first phase of a program to improve ozone measurement techniques. The study concentrated on two measurement systems, the electro chemical cell (ECC) ozonesonde and the Dobson ozone spectrophotometer, and consisted of two tasks. The first task consisted of error modeling and system error analysis of the two measurement systems. Under the second task a Monte-Carlo model of the Dobson ozone measurement technique was developed and programmed for computer operation.

  3. Effects of long-term exposure to low levels of ozone: a review

    SciTech Connect

    Melton, C.E.

    1982-02-01

    Available literature regarding long-term effects of ozone on animals and humans is reviewed. Emphasis is placed on reports that have appeared since 1976, but some earlier reports are cited for completeness and perspective. This review shows that ozone concentration is more important than duration of exposure in determining the effects of an ozone exposure (dose). This conclusion calls into question the validity of the Time-Weighted Average (TWA) as an index of severity of ozone exposure. The literature review further reveals a wide variation in susceptibility of different animal species to ozone, making it difficult to apply results of animal experiments to humans. It further appears that a dose of ozone that is acutely innocuous is also innocuous over the long term. The effects of a symptom-producing dose of ozone are initially cumulative for the first two or three exposures; then an adaptive response may ensue that involves a plateau of response or even reversal. These effects are shown by both animals and humans. The mechanisms are unknown. Ozone probably causes damage by the free radical formation. Free radical scavengers, such as vitamin E and C, may provide protection against ozone damage.

  4. Simulations of ozone distributions in an aircraft cabin using computational fluid dynamics

    NASA Astrophysics Data System (ADS)

    Rai, Aakash C.; Chen, Qingyan

    2012-07-01

    Ozone is a major pollutant of indoor air. Many studies have demonstrated the adverse health effect of ozone and the byproducts generated as a result of ozone-initiated reactive chemistry in an indoor environment. This study developed a Computational Fluid Dynamics (CFD) model to predict the ozone distribution in an aircraft cabin. The model was used to simulate the distribution of ozone in an aircraft cabin mockup for the following cases: (1) empty cabin; (2) cabin with seats; (3) cabin with soiled T-shirts; (4) occupied cabin with simple human geometry; and (5) occupied cabin with detailed human geometry. The agreement was generally good between the CFD results and the available experimental data. The ozone removal rate, deposition velocity, retention ratio, and breathing zone levels were well predicted in those cases. The CFD model predicted breathing zone ozone concentration to be 77-99% of the average cabin ozone concentration depending on the seat location. The ozone concentration at the breathing zone in the cabin environment can better assess the health risk to passengers and can be used to develop strategies for a healthier cabin environment.

  5. Long-term tropical tropospheric ozone column retrievals using the Convective Clouds Differential (CCD) technique

    NASA Astrophysics Data System (ADS)

    Leventidou, Elpida; Ebojie, Felix; Eichmann, Kai-Uwe; Weber, Mark; Burrows, John P.

    2015-04-01

    Ozone influences most of the chemical reactions in the troposphere.Its tropospheric abundance can be retrieved using space-borne observations of vertically integrated ozone and cloud heights. The Convective Clouds Differential (CCD) technique (Ziemke et al., 1998 and Valks et al., 2014) takes advantage of the frequent occurrence of convective clouds in the western Pacific region by subtracting above-cloud ozone of this region from clear-sky ozone elsewhere to derive global monthly mean tropospheric amount. An important assumption is that the above-cloud ozone in the western Pacific simulates the stratospheric ozone and that the stratospheric ozone field is invariant with longitude; which is approximately true in the tropics. A CCD algorithm has been developed and is applied to optical remote sensing observations from three satellite instruments, so that a unique long-term record of monthly averaged tropical (20∘S, 20∘N) tropospheric vertically integrated ozone (1995-2012) is created. The validation of the CCD results with tropospheric ozone data from ozonesondes (Tompson et al., 2003) and Limb-Nadir matching observations (Ebojie et al. 2014) will be presented.

  6. Influence of isentropic transport on seasonal ozone variations in the lower stratosphere and subtropical upper troposphere

    NASA Technical Reports Server (NTRS)

    Jing, P.; Cunnold, D. M.; Yang, E.-S.; Wang, H.-J.

    2005-01-01

    The isentropic cross-tropopause ozone transport has been estimated in both hemispheres in 1999 based on the potential vorticity mapping of Stratospheric Aerosol and Gas Experiment 11 ozone measurements and contour advection calculations using the NASA Goddard Space Flight Center Global and Modeling Assimilation Office analysis. The estimated net isentropic stratosphere-to-troposphere ozone flux is approx.118 +/- 61 x 10(exp9)kg/yr globally within the layer between 330 and 370 K in 1999; 60% of it is found in the Northern Hemisphere, and 40% is found in the Southern Hemisphere. The monthly average ozone fluxes are strongest in summer and weakest in winter in both hemispheres. The seasonal variations of ozone in the lower stratosphere (LS) and upper troposphere (UT) have been analyzed using ozonesonde observations from ozonesonde stations in the extratropics and subtropics, respectively. It is shown that observed ozone levels increase in the UT over subtropical ozonesonde stations and decrease in the LS over extratropical stations in late spring/early summer and that the ozone increases in the summertime subtropical UT are unlikely to be explained by photochemical ozone production and diabatic transport alone. We conclude that isentropic transport is a significant contributor to ozone levels in the subtropical upper troposphere, especially in summer.

  7. Ozone profile measurements at McMurdo Station Antarctica during the spring of 1987

    NASA Technical Reports Server (NTRS)

    Hofmann, D. J.; Harder, J. W.; Rosen, J. M.; Hereford, J.; Carpenter, J. R.

    1988-01-01

    During the Antarctic spring of 1986, 33 ozone soundings were conducted from McMurdo Station. These data indicated that the springtime decrease in ozone occurred rapidly between the altitudes of 12 and 20 km. During 1987, these measurements were repeated with 50 soundings between 29 August and 9 November. Digital conversions of standard electrochemical cell ozonesondes were again employed. The ozonesonde pumps were individually calibrated for flow rate as the high altitude performance of these pumps have been in question. While these uncertainties are not large in the region of the ozone hole, they are significant at high altitude and apparently resulted in an underestimate of total ozone of about 7 percent (average) as compared to the Total Ozone Mapping Spectrometer (TOMS) in 1986, when the flow rate recommended by the manufacturer was used. At the upper altitudes (approx. 30 km) the flow rate may be overestimated by as much as 15 percent using recommended values (see Harder et al., The UW Digital Ozonesonde: Characteristics and Flow Rate Calibration, poster paper, this workshop). These upper level values are used in the extrapolation, at constant mixing ratio, required to complete the sounding for total ozone. The first sounding was on 29 August, prior to major ozone depletion, when 274 DU total ozone (25 DU extrapolated) was observed. By early October total ozone had decreased to the 150 DU range; it then increased during mid-October owing to motion of the vortex and returned to a value of 148 DU (29 DU extrapolated) on 27 October.

  8. Photochemical roles of rapid economic growth and potential abatement strategies on tropospheric ozone over South and East Asia in 2030

    NASA Astrophysics Data System (ADS)

    Chatani, S.; Amann, M.; Goel, A.; Hao, J.; Klimont, Z.; Kumar, A.; Mishra, A.; Sharma, S.; Wang, S. X.; Wang, Y. X.; Zhao, B.

    2014-04-01

    A regional air quality simulation framework including the Weather Research and Forecasting modelling system (WRF), the Community Multi-scale Air Quality modeling system (CMAQ), and precursor emissions to simulate tropospheric ozone over South and East Asia is introduced. Concentrations of tropospheric ozone and related species simulated by the framework are validated by comparing with observation data of surface monitorings, ozone zondes, and satellites obtained in 2010. The simulation demonstrates acceptable performance on tropospheric ozone over South and East Asia at regional scale. Future energy consumption, carbon dioxide (CO2), nitrogen oxides (NOx), and volatile organic compound (VOC) emissions in 2030 under three future scenarios are estimated. One of the scenarios assumes a business-as-usual (BAU) pathway, and other two scenarios consider implementation of additional energy and environmental strategies to reduce energy consumption, CO2, NOx, and VOC emissions in China and India. Future surface ozone under these three scenarios is predicted by the simulation. The simulation indicates future surface ozone significantly increases around India for a whole year and around north eastern China in summer. NOx is a main driver on significant seasonal increase of surface ozone, whereas VOC as well as increasing background ozone and methane is also an important factor on annual average of surface ozone in East Asia. Warmer weather around India is also preferable for significant increase of surface ozone. Additional energy and environmental strategies assumed in future scenarios are expected to be effective to reduce future surface ozone over South and East Asia.

  9. Comparison of Wintertime Ozone Production Associated With Oil and Gas Extraction Activity in Wyoming and Utah

    NASA Astrophysics Data System (ADS)

    Oltmans, S. J.; Schnell, R. C.; Mefford, T. K.; Neely, R. R., III

    2012-12-01

    The wintertime cold, reduced sunlight conditions of the mid-latitudes of continental interior locations are normally not considered to be conducive to significant ozone production. Recent observations have shattered this expectation with hourly ozone mixing ratios regularly exceeding 100 ppb measured in January, February and March in the states of Wyoming and Utah in the United States. Maximum daily eight hour average ozone mixing ratios have exceeded 100 ppb, far exceeding the U.S. threshold of 75 ppb. Conditions under which this dramatic ozone production takes place include a mix of high levels of ozone precursors (NOx and VOCs), a very stable and shallow boundary layer, snow cover providing enhanced UV radiation, and air confining terrain features. The high levels of precursors have been tied to oil and gas extraction activities in the affected regions. Under the requisite meteorological conditions where high pressure, low winds, and snow-covered ground are present extremely stable and shallow (~50-200 m) boundary layers persist. The highly reflective snow cover provides enhanced photolysis rates that in February can exceed those in June. For several winters in Utah and Wyoming with large ozone enhancements, the time series of various meteorological (wind, temperature, solar radiation, snow cover) and chemical parameters (ozone and NOx) show a somewhat different progression of high ozone events between the two locations. In the Unitah Basin of Utah high ozone formation conditions are more persistent throughout the winter than in the Pinedale Anticline region of Wyoming. This is likely a function of the differing topography of the two areas. However, for individual events the two sites show a similar progression of rapid ozone formation each day. Sites in both Utah and Wyoming just outside the oil and gas extraction activity areas show little or no enhanced ozone. Winters without the requisite meteorological conditions also do not experience high ozone events.

  10. A New Linearized Photochemistry Parameterization for Operational Ozone Assimilation in Numerical Weather Prediction Systems

    NASA Astrophysics Data System (ADS)

    McCormack, J. P.; Allen, D. R.; Coy, L.; Eckermann, S. D.; Stajner, I.

    2005-12-01

    The Ozone Mapping and Profiler Suite (OMPS) will deliver real-time ozone data for assimilation in numerical weather prediction (NWP) models. This information will benefit forecasts by improving the modeled stratospheric heating rates and providing better first-guess temperature profiles needed for infrared satellite radiance retrieval algorithms. Operational ozone data assimilation for NWP requires a fast, accurate treatment of stratospheric ozone photochemistry. We present results from the new NRL CHEM2D Ozone Photochemistry Parameterization (CHEM2D-OPP), which is based on output from the zonally averaged NRL-CHEM2D middle atmosphere photochemical-transport model. CHEM2D-OPP is a linearized parameterization of gas-phase stratospheric ozone photochemistry developed for NOGAPS-ALPHA, the Navy's prototype global high altitude NWP model. A recent study of NOGAPS-ALPHA ozone simulations found that a preliminary version of the CHEM2D-based photochemistry parameterization generally performed better than other current photochemistry schemes that are now widely used in operational NWP and data assimilation systems. A new, improved version of CHEM2D-OPP is now available. Here we report the first quantitative performance assessments of the updated CHEM2D-OPP package in the NRL Global Ozone Assimilation Testing System (GOATS). This study compares the mean differences between GOATS ozone analyses and SBUV/2 ozone measurements (both vertical profile and total column) during September 2002 using several different ozone photochemistry schemes. We find that CHEM2D-OPP generally delivers the best performance out of all the photochemistry schemes we tested. Future development plans for CHEM2D-OPP, such as interfacing it with a "cold tracer" parameterization for heterogeneous ozone-hole chemistry, will also be presented.

  11. Comparison of satellite measurements of ozone and ozone trends

    SciTech Connect

    Rusch, D.W.; Clancy, R.T.; Bhartia, P.K. |

    1994-10-01

    Measurements of ozone retrieved from satellite instruments over the 1979-1991 period are compared. The instruments used are the total ozone mapping spectrometer (TOMS), the solar backscattered ultraviolet experiment (SBUV), and stratospheric aerosol and gas experiments (SAGE) I and II. Although there is good agreement between the absolute densities of ozone as measured by the various instruments, the long-term changes (1979-1990) disagree sharply as a function of pressure and in the integrated ozone amount. In the upper stratosphere, SBUV trends are negative with maximum values of about -1.5%/year at high latitudes. Combined SAGE I and II trends are slightly positive in this region and peak near 0.5%/year at equatorial latitudes. In the lower stratosphere, SBUV trends reflect small decreases in ozone, generally less than -0.4%/year except at high southern latitudes where the trends rearch values of approximately -1.5%/year. SAGE ozone trends exhibit large decreases particularly in the equatorial regions where decreases of 3-6%/year are seen at pressures between 60 and 90 mbar. At higher latitudes, SAGE trends are more comparable to SBUV trends in the lower stratosphere. Total ozone trends from TOMS and SBUV agree within their uncertainties. Near-zero trends are indicated at low latitudes, and larger, negative trends (approximately -0.5%/year) are indicated near the poles. The SAGE column ozone trends depend upon the base level altitude of integration but do not exhibit a strong latitude dependence.

  12. Draft Genome Sequence of an Escherichia coli O8:H19 Sequence Type 708 Strain Isolated from a Holstein Dairy Cow with Metritis.

    PubMed

    Ginn, Amber; Ma, Zhengxin; Galvao, Klibs N; Jeong, KwangCheol Casey

    2016-01-01

    We present here the genome sequence ofEscherichia coliO8:H19 strain KCJ852, belonging to multilocus sequence type (MLST) 708, isolated from the uterus of a cow with a bovine postpartum uterine infection known as metritis. Genomic investigation of KCJ852 will help us understand its virulence potential. PMID:27056235

  13. Draft Genome Sequence of an Escherichia coli O8:H19 Sequence Type 708 Strain Isolated from a Holstein Dairy Cow with Metritis

    PubMed Central

    Ginn, Amber; Ma, Zhengxin; Galvao, Klibs N.

    2016-01-01

    We present here the genome sequence of Escherichia coli O8:H19 strain KCJ852, belonging to multilocus sequence type (MLST) 708, isolated from the uterus of a cow with a bovine postpartum uterine infection known as metritis. Genomic investigation of KCJ852 will help us understand its virulence potential. PMID:27056235

  14. Ultraviolet Radiation and Stratospheric Ozone

    NASA Technical Reports Server (NTRS)

    Stolarski, R.

    2003-01-01

    Ultraviolet radiation from the sun produces ozone in the stratosphere and it participates in the destruction of ozone. Absorption of solar ultraviolet radiation by ozone is the primary heating mechanism leading to the maximum in temperature at the stratopause. Variations of solar ultraviolet radiation on both the 27-day solar rotation period and the 11-year solar cycle affect ozone by several mechanisms. The temperature and ozone in the upper stratosphere respond to solar uv variations as a coupled system. An increase in uv leads to an increase in the production of ozone through the photolysis of molecular oxygen. An increase in uv leads to an increase in temperature through the heating by ozone photolysis. The increase in temperature leads to a partially-offsetting decrease in ozone through temperature-dependent reaction rate coefficients. The ozone variation modulates the heating by ozone photolysis. The increase in ozone at solar maximum enhances the uv heating. The processes are understood and supported by long-term data sets. Variation in the upper stratospheric temperatures will lead to a change in the behavior of waves propagating upward from the troposphere. Changes in the pattern of wave dissipation will lead to acceleration or deceleration of the mean flow and changes in the residual or transport circulation. This mechanism could lead to the propagation of the solar cycle uv variation from the upper stratosphere downward to the lower stratosphere. This process is not well-understood and has been the subject of an increasing number of model studies. I will review the data analyses for solar cycle and their comparison to model results.

  15. Impact of regional meteorology on ozone levels in the Lake Tahoe Basin

    NASA Astrophysics Data System (ADS)

    Rayne, Sandra; Gertler, Alan; Zielinska, Barbara; Bytnerowicz, Andrzej; Burley, Joel; Kaplan, Michael

    2016-07-01

    The Lake Tahoe Basin is located on the California-Nevada border and occasionally experiences elevated levels of ozone (O3) exceeding the California Air Resources Board ambient air quality standard (8-h average). Previous studies indicate that both the local generation and long-range transport from out-of-basin sources are important in contributing to O3 exceedances, but little is known about the impact of regional meteorology on O3 source regions. To develop a better understanding of the factors affecting O3 levels and sources in the Lake Tahoe Basin, a comprehensive field study was performed in the summer of 2010. Included in this effort was a meteorological analysis addressing potential regional meteorological influences leading to periods of elevated levels of O3. Three approaches were used to conduct the analysis: (1) regional atmospheric pressure difference (i.e., the Washoe Zephyr) to access potential transport, (2) back trajectory modeling using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model to determine where the air masses originated and, (3) composite soundings to evaluate in-Basin atmospheric influences. These analyses indicate the Washoe Zephyr did not strongly impact O3 levels; however, higher O3 levels were found to correspond with both a more southerly wind component and a dip in dew point temperature around 400 hPa. The results also indicate that if transport does occur, it is more likely to come from the San Joaquin Valley and move to the southern part of the Basin, rather than originating in the large cities to the west (i.e., Sacramento and San Francisco).

  16. Virtual Averaging Making Nonframe-Averaged Optical Coherence Tomography Images Comparable to Frame-Averaged Images

    PubMed Central

    Chen, Chieh-Li; Ishikawa, Hiroshi; Wollstein, Gadi; Bilonick, Richard A.; Kagemann, Larry; Schuman, Joel S.

    2016-01-01

    Purpose Developing a novel image enhancement method so that nonframe-averaged optical coherence tomography (OCT) images become comparable to active eye-tracking frame-averaged OCT images. Methods Twenty-one eyes of 21 healthy volunteers were scanned with noneye-tracking nonframe-averaged OCT device and active eye-tracking frame-averaged OCT device. Virtual averaging was applied to nonframe-averaged images with voxel resampling and adding amplitude deviation with 15-time repetitions. Signal-to-noise (SNR), contrast-to-noise ratios (CNR), and the distance between the end of visible nasal retinal nerve fiber layer (RNFL) and the foveola were assessed to evaluate the image enhancement effect and retinal layer visibility. Retinal thicknesses before and after processing were also measured. Results All virtual-averaged nonframe-averaged images showed notable improvement and clear resemblance to active eye-tracking frame-averaged images. Signal-to-noise and CNR were significantly improved (SNR: 30.5 vs. 47.6 dB, CNR: 4.4 vs. 6.4 dB, original versus processed, P < 0.0001, paired t-test). The distance between the end of visible nasal RNFL and the foveola was significantly different before (681.4 vs. 446.5 μm, Cirrus versus Spectralis, P < 0.0001) but not after processing (442.9 vs. 446.5 μm, P = 0.76). Sectoral macular total retinal and circumpapillary RNFL thicknesses showed systematic differences between Cirrus and Spectralis that became not significant after processing. Conclusion The virtual averaging method successfully improved nontracking nonframe-averaged OCT image quality and made the images comparable to active eye-tracking frame-averaged OCT images. Translational Relevance Virtual averaging may enable detailed retinal structure studies on images acquired using a mixture of nonframe-averaged and frame-averaged OCT devices without concerning about systematic differences in both qualitative and quantitative aspects. PMID:26835180

  17. Averaging Models: Parameters Estimation with the R-Average Procedure

    ERIC Educational Resources Information Center

    Vidotto, G.; Massidda, D.; Noventa, S.

    2010-01-01

    The Functional Measurement approach, proposed within the theoretical framework of Information Integration Theory (Anderson, 1981, 1982), can be a useful multi-attribute analysis tool. Compared to the majority of statistical models, the averaging model can account for interaction effects without adding complexity. The R-Average method (Vidotto &…

  18. An assessment of ozone concentrations within and near the Lake Tahoe Air Basin

    NASA Astrophysics Data System (ADS)

    Dolislager, Leon J.; VanCuren, Richard; Pederson, James R.; Lashgari, Ash; McCauley, Eileen

    2012-01-01

    The Lake Tahoe Atmospheric Deposition Study (LTADS) was conducted by the Air Resources Board of the State of California (CARB) primarily to generate refined estimates of the atmospheric deposition of nitrogen, phosphorous, and particulate matter directly to Lake Tahoe, which straddles the border between the states of California and Nevada near Reno, Nevada. The enhanced air quality monitoring during LTADS also included ozone measurements, which yielded additional insights into atmospheric processes and the role of transport in determining ozone concentrations within the Lake Tahoe Air Basin. The Lake Tahoe Air Basin is located generally downwind of air basins with major emissions of ozone precursors (e.g., VOCs, NOx), capable of generating significant ozone concentrations. Furthermore, vegetation on the western slope of the Sierra Nevada contribute biogenic organic compounds to the air mass. Ozone concentrations within the Tahoe Basin infrequently exceed the local 1-h threshold set to protect forest health (0.08 ppm) and the California 8-h ambient air quality standard (0.070 ppm). A concern then is the potential contribution of regional emission sources to the ozone concentrations observed in the Tahoe Basin. The ozone data collected during LTADS helped to better characterize the relative contribution of local and regional pollution sources to ozone air quality within the Tahoe Basin. The data indicate potential 1- or 2-day intact transport on rare occasions but generally the mixing of the atmosphere over the Sierra Nevada disperses the anthropogenic ozone throughout the boundary layer, which is generally more than a kilometer or two deep during the day. The data analysis indicates that emissions from upwind air basins add to the atmospheric burden of ozone concentrations, raising the regional concentrations in the Sierra Nevada. Given the large background and upwind enhancements relative to the ambient air quality standards, the local contribution does not need to

  19. Ozone dose-response relationships for spring oilseed rape and broccoli

    NASA Astrophysics Data System (ADS)

    De Bock, Maarten; Op de Beeck, Maarten; De Temmerman, Ludwig; Guisez, Yves; Ceulemans, Reinhart; Vandermeiren, Karine

    2011-03-01

    Tropospheric ozone is an important air pollutant with known detrimental effects for several crops. Ozone effects on seed yield, oil percentage, oil yield and 1000 seed weight were examined for spring oilseed rape ( Brassica napus cv. Ability). For broccoli ( Brassica oleracea L. cv. Italica cv. Monaco) the effects on fresh marketable weight and total dry weight were studied. Current ozone levels were compared with an increase of 20 and 40 ppb during 8 h per day, over the entire growing season. Oilseed rape seed yield was negatively correlated with ozone dose indices calculated from emergence until harvest. This resulted in an R2 of 0.24 and 0.26 ( p < 0.001) for the accumulated hourly O 3 exposure over a threshold of 40 ppb (AOT40) and the phytotoxic ozone dose above a threshold of 6 nmol m -2 s -1 (POD 6) respectively. Estimated critical levels, above which 5% yield reduction is expected, were 3.7 ppm h and 4.4 mmol m -2 respectively. Our results also confirm that a threshold value of 6 nmol s -1 m -2 projected leaf area, as recommended for agricultural crops (UNECE, Mills, 2004), can indeed be applied for spring oilseed rape. The reduction of oilseed rape yield showed the highest correlation with the ozone uptake during the vegetative growth stage: when only the first 47 days after emergence were used to calculate POD 6, R2 values increased up to 0.476 or even 0.545 when the first 23 days were excluded. The highest ozone treatments, corresponding to the future ambient level by 2100 (IPCC, Meehl et al., 2007), led to a reduction of approximately 30% in oilseed rape seed yield in comparison to the current ozone concentrations. Oil percentage was also significantly reduced in response to ozone ( p < 0.001). As a consequence oil yield was even more severely affected by elevated ozone exposure compared to seed yield: critical levels for oil yield dropped to 3.2 ppm h and 3.9 mmol m -2. For broccoli the applied ozone doses had no effect on yield.

  20. Equatorial ozone characteristics as measured at Natal (5.9 deg S, 35.2 deg W)

    NASA Technical Reports Server (NTRS)

    Kirchhoff, V. W. J. H.; Motta, A. G.; Sahai, Y.; Medrano-B., R. A.; Hilsenrath, E.

    1983-01-01

    Ozone density profiles obtained through electrochemical concentration cell (ECC) sonde measurements at Natal were analyzed. Time variations, as expected, are small. Outstanding features of the data are tropospheric densities substantially higher than those measured at other stations, and also a total ozone content that is higher than the averages given by satellite measurements. Previously announced in STAR as A82-29798

  1. Equatorial ozone characteristics as measured at Natal (5.9 deg S, 35.2 deg W)

    NASA Technical Reports Server (NTRS)

    Kirchhoff, V. W. J. H.; Hilsenrath, E.; Motta, A. G.; Sahai, Y.; Medrano-B, R. A.

    1982-01-01

    Ozone density profiles obtained through electrochemical concentration cell (ECC) sonde measurements at Natal were analyzed. Time variations, as expected, are small. Outstanding features of the data are tropospheric densities substantially higher than those measured at other stations, and also a total ozone content that is higher than the averages given by satellite measurements.

  2. IMPACT OF OZONE ON VEGETATION

    EPA Science Inventory

    Visible injury on vegetation is one of the earliest and most obvious manifestations of ozone injury. However, ozone effects are not limited to visible injury; impacts range from reduced plant growth, decreased yield, changes in crop quality and alterations in susceptibility to ab...

  3. Rocket ozone sounding network data

    NASA Technical Reports Server (NTRS)

    Wright, D. U.; Krueger, A. J.; Foster, G. M.

    1978-01-01

    During the period December 1976 through February 1977, three regular monthly ozone profiles were measured at Wallops Flight Center, two special soundings were taken at Antigua, West Indies, and at the Churchill Research Range, monthly activities were initiated to establish stratospheric ozone climatology. This report presents the data results and flight profiles for the period covered.

  4. IMPROVED TECHNIQUES FOR RESIDUAL OZONE

    EPA Science Inventory

    Eight analytical methods for the determination of residual ozone in water are evaluated. Four are iodometric methods based on the reduction of ozone by iodide ion: the iodometric method, the amperometric method, the arsenic (III) back titration method, and the N, N-diethyl-p-phen...

  5. Simplified ozone detection by chemiluminescence

    NASA Technical Reports Server (NTRS)

    Conway, E. J.; Rogowski, R. S.; Richards, R. R.

    1977-01-01

    Ozone is detected by film coated with solid, such as rubrene, that reacts with ozone to degree proportional to concentration in sample gas. Gas flow is stopped, and film is heated to produce light (chemiluminescence) in proportion to amount of reacted material on sensor.

  6. Plant responses to tropospheric ozone

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Tropospheric ozone is the second most abundant air pollutant and an important component of the global climate change. Over five decades of research on the phytotoxicity of ozone in model plants systems, crop plants and forest trees have provided some insight into the physiological, biochemical and m...

  7. OZONE MULTI-YEAR PLAN

    EPA Science Inventory

    The tropospheric ozone research program addresses not only ozone, but other criteria pollutants such as SO2, nitrogen dioxide, carbon monoxide, and lead. It focuses on developing tools to help with implementation of National Ambient Air Quality Standards (NAAQS), such as improvin...

  8. Ozone Modeling Using Neural Networks.

    NASA Astrophysics Data System (ADS)

    Narasimhan, Ramesh; Keller, Joleen; Subramaniam, Ganesh; Raasch, Eric; Croley, Brandon; Duncan, Kathleen; Potter, William T.

    2000-03-01

    Ozone models for the city of Tulsa were developed using neural network modeling techniques. The neural models were developed using meteorological data from the Oklahoma Mesonet and ozone, nitric oxide, and nitrogen dioxide (NO2) data from Environmental Protection Agency monitoring sites in the Tulsa area. An initial model trained with only eight surface meteorological input variables and NO2 was able to simulate ozone concentrations with a correlation coefficient of 0.77. The trained model was then used to evaluate the sensitivity to the primary variables that affect ozone concentrations. The most important variables (NO2, temperature, solar radiation, and relative humidity) showed response curves with strong nonlinear codependencies. Incorporation of ozone concentrations from the previous 3 days into the model increased the correlation coefficient to 0.82. As expected, the ozone concentrations correlated best with the most recent (1-day previous) values. The model's correlation coefficient was increased to 0.88 by the incorporation of upper-air data from the National Weather Service's Nested Grid Model. Sensitivity analysis for the upper-air variables indicated unusual positive correlations between ozone and the relative humidity from 500 hPa to the tropopause in addition to the other expected correlations with upper-air temperatures, vertical wind velocity, and 1000-500-hPa layer thickness. The neural model results are encouraging for the further use of these systems to evaluate complex parameter cosensitivities, and for the use of these systems in automated ozone forecast systems.

  9. Rocket ozone sounding network data

    NASA Technical Reports Server (NTRS)

    Wright, D. U.; Krueger, A. J.; Foster, G. M.

    1979-01-01

    During the period March 1977 through May 1977, three regular monthly ozone profiles were measured at Wallops Flight Center and three regular monthly ozone profiles were measured at the Churchill Research Range. One additional flight was conducted at Wallops Flight Center in support of Nimbus 4 SBUV. Data results and flight profiles for the period covered are presented.

  10. Nonaqueous ozonation of vulcanized rubber

    DOEpatents

    Serkiz, Steven M.

    1999-01-01

    A process and resulting product is provided in which a solid particulate, such as vulcanized crumb rubber, has the surface functional groups oxidized by ozonation using a nonpolar solvent. The ozonation process renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels of the treated crumb rubber can be used in new rubber mixtures.

  11. Nonaqueous ozonation of vulcanized rubber

    SciTech Connect

    Serkiz, S.M.

    1999-12-07

    A process and resulting product are provided in which a solid particulate, such as vulcanized crumb rubber, has the surface functional groups oxidized by ozonation using a nonpolar solvent. The ozonation process renders the treated crumb rubber more suitable for use in new rubber formulations. As a result, larger loading levels of the treated crumb rubber can be used in new rubber mixtures.

  12. Ozone loss rates calculated along ER-2 flight tracks

    SciTech Connect

    Murphy, D.M. )

    1991-03-20

    Local ozone loss rates due to the ClO+ClO and BrO+ClO cycles are calculated using ClO, pressure, and temperature from in-situ aircraft measurements and representative BrO mixing ratios. Ozone loss during the vertical profiles executed by the ER-2 near 72{degree}S usually extended over a deep altitude range rather than reaching a maximum at the top of the profiles. This is due to the strong pressure dependence of the rate determining steps. In the Antarctic, very high ozone loss rates (>5{center dot}10{sup 6} cm{sup {minus}3} s{sup {minus}1}) were observed at altitudes with potential temperatures below 400 K, where advective exchange is likely to be much more rapid than at higher altitudes. On September 22, 1987, the ER-2 measured an ozone loss rate of aboutn 2.8 Dobson units (DU) per 12 sunlit hours in the 350-400 K range and 2.0 DU in the 400-450 K range near 72{degree}S. Rapid ozone loss in the Arctic did not extend below 400 K in the available data. The calculated average loss rate, which is nonlinear, in general depends on the order in which the terms are averaged. Loss rates calculated by averaging the ClO, pressure and temperature for up to 2,400 s (about 500 km) generally agree with the average of the local loss rate to within one percent except at the edge of the vortex, where the difference can be up to 30%. Adiabatic temperature and pressure effects nearly cancel. Thermal decomposition of Cl{sub 2}O{sub 2} was not important along sunlit portions of ER-2 flight tracks if equilibrium is assumed between ClO and Cl{sub 2}O{sub 2}. The effect of recalibration of the ClO data on the calculated loss rates is discussed.

  13. The sensitivity of modeled ozone to the temporal distribution of point, area, and mobile source emissions in the eastern United States

    NASA Astrophysics Data System (ADS)

    Castellanos, Patricia; Stehr, Jeffrey W.; Dickerson, Russell R.; Ehrman, Sheryl H.

    Ozone remains one of the most recalcitrant air pollution problems in the US. Hourly emissions fields used in air quality models (AQMs) generally show less temporal variability than corresponding measurements from continuous emissions monitors (CEM) and field campaigns would imply. If emissions control scenarios to reduce emissions at peak ozone forming hours are to be assessed with AQMs, the effect of emissions' daily variability on modeled ozone must be understood. We analyzed the effects of altering all anthropogenic emissions' temporal distributions by source group on 2002 summer-long simulations of ozone using the Community Multiscale Air Quality Model (CMAQ) v4.5 and the Carbon Bond IV (CBIV) chemical mechanism with 12 km resolution. We find that when mobile source emissions were made constant over the course of a day, 8-h maximum ozone predictions changed by ±7 parts per billion by volume (ppbv) in many urban areas on days when ozone concentrations greater than 80 ppbv were simulated in the base case. Increasing the temporal variation of point sources resulted in ozone changes of +6 and -6 ppbv, but only for small areas near sources. Changing the daily cycle of mobile source emissions produces substantial changes in simulated ozone, especially in urban areas at night; results suggest that shifting the emissions of NO x from day to night, for example in electric powered vehicles recharged at night, could have beneficial impacts on air quality.

  14. Direct measurements of tropospheric ozone from TOMS data

    NASA Technical Reports Server (NTRS)

    Hudson, Robert D.

    1993-01-01

    In the past year, we have made measurements of the tropospheric total column of ozone during the biomass burning season in Africa (August to October). Fishman et. al. had reported previously that by taking a time average of the low spatial resolution data from TOMS (Total Ozone Mapping Spectrometer) on Nimbus-7 (referred to as the Grid-T data set), during the biomass burning season in Africa, a plume of ozone extends from the East coast of Africa into the Atlantic. In this report, we present an analysis that we have made using the measured TOMS radiances taken from the High Density TOMS data set (referred as the HDT data set), which examines this plume in more detail.

  15. Source attribution of tropospheric ozone

    NASA Astrophysics Data System (ADS)

    Butler, T. M.

    2015-12-01

    Tropospheric ozone is a harmful pollutant with adverse effects on human health and ecosystems. As well as these effects, tropospheric ozone is also a powerful greenhouse gas, with an anthropogenic radiative forcing one quarter of that of CO2. Along with methane and atmospheric aerosol, tropospheric ozone belongs to the so-called Short Lived Climate forcing Pollutants, or SLCP. Recent work has shown that efforts to reduce concentrations of SLCP in the atmosphere have the potential to slow the rate of near-term climate change, while simultaneously improving public health and reducing crop losses. Unlike many other SLCP, tropospehric ozone is not directly emitted, but is instead influenced by two distinct sources: transport of air from the ozone-rich stratosphere; and photochemical production in the troposphere from the emitted precursors NOx (oxides of nitrogen), CO (Carbon Monoxide), and VOC (volatile organic compounds, including methane). Better understanding of the relationship between ozone production and the emissions of its precursors is essential for the development of targeted emission reduction strategies. Several modeling methods have been employed to relate the production of tropospheric ozone to emissions of its precursors; emissions perturbation, tagging, and adjoint sensitivity methods all deliver complementary information about modelled ozone production. Most studies using tagging methods have focused on attribution of tropospheric ozone production to emissions of NOx, even though perturbation methods have suggested that tropospheric ozone is also sensitive to VOC, particularly methane. In this study we describe the implementation into a global chemistry-climate model of a scheme for tagging emissions of NOx and VOC with an arbitrary number of labels, which are followed through the chemical reactions of tropospheric ozone production in order to perform attribution of tropospehric ozone to its emitted precursors. Attribution is performed to both

  16. Clathrate hydrates for ozone preservation.

    PubMed

    Muromachi, Sanehiro; Ohmura, Ryo; Takeya, Satoshi; Mori, Yasuhiko H

    2010-09-01

    We report the experimental evidence for the preservation of ozone (O(3)) encaged in a clathrate hydrate. Although ozone is an unstable substance and is apt to decay to oxygen (O(2)), it may be preserved for a prolonged time if it is encaged in hydrate cavities in the form of isolated molecules. This possibility was assessed using a hydrate formed from an ozone + oxygen gas mixture coexisting with carbon tetrachloride or xenon. Each hydrate sample was stored in an air-filled container at atmospheric pressure and a constant temperature in the range between -20 and 2 degrees C and was continually subjected to iodometric measurements of its fractional ozone content. Such chronological measurements and structure analysis using powder X-ray diffraction have revealed that ozone can be preserved in a hydrate-lattice structure for more than 20 days at a concentration on the order of 0.1% (hydrate-mass basis). PMID:20707330

  17. Ozone adsorption on carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Chassard, Guillaume; Gosselin, Sylvie; Visez, Nicolas; Petitprez, Denis

    2014-05-01

    Carbonaceous particles produced by incomplete combustion or thermal decomposition of hydrocarbons are ubiquitous in the atmosphere. On these particles are adsorbed hundreds of chemical species. Those of great concern to health are polycyclic aromatic hydrocarbons (PAHs). During atmospheric transport, particulate PAHs react with gaseous oxidants. The induced chemical transformations may change toxicity and hygroscopicity of these potentially inhalable particles. The interaction between ozone and carbon particles has been extensively investigated in literature. However ozone adsorption and surface reaction mechanisms are still ambiguous. Some studies described a fast catalytic decomposition of ozone initiated by an atomic oxygen chemisorption followed by a molecular oxygen release [1-3]. Others suggested a reversible ozone adsorption according to Langmuir-type behaviour [4,5]. The aim of this present study is a better understanding of ozone interaction with carbon surfaces. An aerosol of carbon nanoparticles was generated by flowing synthetic air in a glass tube containing pure carbon (primary particles < 50 nm), under magnetic stirring. The aerosol was then mixed with ozone in an aerosol flow tube. Ozone uptake experiments were performed with different particles concentrations with a fixed ozone concentration. The influence of several factors on kinetics was examined: initial ozone concentration, particle size (50 nm ≤ Dp ≤ 200 nm) and competitive adsorption (with probe molecule and water). The effect of initial ozone concentration was first studied. Accordingly to literature, it has been observed that the number of gas-phase ozone molecules lost per unit particle surface area tends towards a plateau for high ozone concentration suggesting a reversible ozone adsorption according to a Langmuir mechanism. We calculated the initial reaction probability between O3 and carbon particles.An initial uptake coefficient of 1.10-4 was obtained. Similar experiments were

  18. Latest tendency in the Antarctic ozone longitudinal distribution

    NASA Astrophysics Data System (ADS)

    Milinevsky, Gennadi; Grytsai, Asen; Klekociuk, Andrew; Evtushevsky, Olexander

    2014-05-01

    Significant ozone depletion was observed within the southern polar vortex during spring in the 1980s - early 1990s. Later, a stabilization in total ozone levels and ozone hole area has been observed. Atmosphere models predict a consequent recovery of the Antarctic ozone. Nevertheless, identification of the long-term processes is complicated by high interannual variability hiding their general regularities. In particular, a large stratosphere warming in 2002 resulted in significant increase in total ozone levels. The Antarctic ozone hole is formed inside polar stratospheric vortex, which is under influence of large-scale planetary waves. The components of the quasi-stationary wave (QSW) in the spring Southern Hemisphere (SH) stratosphere is mainly contributed by zonal wave number 1 which in turn determines the location of the total ozone extremes in spring: QSW minimum (maximum) is located in the South Atlantic (Australian) sector. In our work the satellite data of TOMS/Nimbus-7, TOMS/Earth Probe and OMI/Aura (http://ozoneaq.gsfc.nasa.gov/) have been used to investigate longitudinal distribution of the total ozone in Antarctic region. The gap in these satellite observations (1993-1995) was filled by the Multi-Sensor Reanalysis data (http://www.temis.nl/). Ozone distribution in the SH high and mid latitudes 80-50S were analyzed for southern spring season including months from September to November. The zonal distribution is considered along seven latitude circles from 80S to 50S with step of five degrees. To distinguish long-term processes and to obtain a quasi-stationary pattern, daily September - November ozone was averaged. Our previous study demonstrated a systematic eastward shift of the QSW minimum region. In this study, we extended the analysis to 2013 and obtained new results that exhibited a probable cessation in that eastward shift. Polynomial fit for all chosen latitudes is even evidence of a change in the tendency to opposite. It more time needs to

  19. Exposure to Environmental Ozone Alters Semen Quality

    PubMed Central

    Sokol, Rebecca Z.; Kraft, Peter; Fowler, Ian M.; Mamet, Rizvan; Kim, Elizabeth; Berhane, Kiros T.

    2006-01-01

    Idiopathic male infertility may be due to exposure to environmental toxicants that alter spermatogenesis or sperm function. We studied the relationship between air pollutant levels and semen quality over a 2-year period in Los Angeles, California, by analyzing repeated semen samples collected by sperm donors. Semen analysis data derived from 5,134 semen samples from a sperm donor bank were correlated with air pollutant levels (ozone, nitrogen dioxide, carbon monoxide, and particulate matter < 10 μm in aerodynamic diameter) measured 0–9, 10–14, and 70–90 days before semen collection dates in Los Angeles between January 1996 and December 1998. A linear mixed-effects model was used to model average sperm concentration and total motile sperm count for the donation from each subject. Changes were analyzed in relationship to biologically relevant time points during spermatogenesis, 0–9, 10–14, and 70–90 days before the day of semen collection. We estimated temperature and seasonality effects after adjusting for a base model, which included donor’s date of birth and age at donation. Forty-eight donors from Los Angeles were included as subjects. Donors were included if they collected repeated semen samples over a 12-month period between January 1996 and December 1998. There was a significant negative correlation between ozone levels at 0–9, 10–14, and 70–90 days before donation and average sperm concentration, which was maintained after correction for donor’s birth date, age at donation, temperature, and seasonality (p < 0.01). No other pollutant measures were significantly associated with sperm quality outcomes. Exposure to ambient ozone levels adversely affects semen quality. PMID:16507458

  20. An assessment of ozone levels, UV radiation and their occupational health hazard estimation during photocopying operation.

    PubMed

    Singh, Bhupendra Pratap; Kumar, Amit; Singh, Deepak; Punia, Monika; Kumar, Krishan; Jain, Vinod Kumar

    2014-06-30

    This study investigates the levels of ozone concentration along with an ultraviolet (UV) and visible spectral radiation at eight photocopy centers in an academic institute, Delhi. Sampling was done in two types of locations, i.e., basement photocopy centers (BPC) and ground floor photocopy centers (GPC) for 8h. Measurements of levels of ozone, UV and visible radiation were done by ozone analyzer, UV radiometer and Field spectra instrument, respectively. Results show that the hourly mean concentration of ozone was observed to be in the range of 1.8-10.0 ppb and 5.3-45.8 ppb for BPC and GPC, respectively. In terms UV radiations, energy lies between 5.0×10(-3) and 7.0×10(-3) mW/cm(2) for ultraviolet A (UVA), 1.0×10(-3) and 2.0×10(-3) mW/cm(2) for ultraviolet B (UVB) and 6.0×10(-3) and 8.0×10(-3) mW/cm(2) for ultraviolet C (UVC). Correlation between the UV radiations and ozone production observed was statistically insignificant. To know the health hazard occurred to the workers, the standard erythema dose (SED) value was calculated for emitting UV radiation. The SED was estimated to be in the range of 0.02-0.04 and 0.02-0.32 for direct and indirect methods which is less than the guideline prescribed by Commission Internationale del' Eclairage (CIE). In nutshell, person involved in photocopy operation for their livelihood must be trained and should have knowledge for the long term gradual build up health problems due to ozone and UV production from photocopier. The manufactures should be ultimated with the significant ozone production, so that photocopier machine can be redesigned. PMID:24857892

  1. Trends of Rural Tropospheric Ozone at the Northwest of the Iberian Peninsula

    PubMed Central

    Saavedra, S.; Rodríguez, A.; Souto, J. A.; Casares, J. J.; Bermúdez, J. L.; Soto, B.

    2012-01-01

    Tropospheric ozone levels around urban and suburban areas at Europe and North America had increased during 80's–90's, until the application of NOx reduction strategies. However, as it was expected, this ozone depletion was not proportional to the emissions reduction. On the other hand, rural ozone levels show different trends, with peaks reduction and average increments; this different evolution could be explained by either emission changes or climate variability in a region. In this work, trends of tropospheric ozone episodes at rural sites in the northwest of the Iberian Peninsula were analyzed and compared to others observed in different regions of the Atlantic European coast. Special interest was focused on the air quality sites characterization, in order to guarantee their rural character in terms of air quality. Both episodic local meteorological and air quality measurements along five years were considered, in order to study possible meteorological influences in ozone levels, different to other European Atlantic regions. PMID:22649298

  2. Effects of the 2004 El Nino on Tropospheric Ozone and Water Vapor

    NASA Technical Reports Server (NTRS)

    Chandra, S.; Ziemke, J. R.; Schoeberl, M. R.; Froidevaux, L.; Read, W. G.; Levelt, P. F.; Bhartia, P. K.

    2007-01-01

    The global effects of the 2004 El Nino on tropospheric ozone and H2O based on Aura OM1 and MLS measurements are analyzed. Although it was a weak El Nino from a historical perspective, it produced significant changes in these parameters in tropical latitudes. Tropospheric ozone increased by 10-20% over most of the western Pacific region and decreased by about the same amount over the eastern Pacific region. H2O in the upper troposphere showed similar changes but with opposite sign. These zonal changes in tropospheric ozone and H2O are caused by the eastward shift in the Walker circulation in the tropical pacific region during El Nino. For the 2004 El Nino, biomass burning did not have a significant effect on the ozone budget in the troposphere unlike the 1997 El Nino. Zonally averaged tropospheric column ozone did not change significantly either globally or over the tropical and subtropical latitudes.

  3. Seasonal Variability in Tropospheric Ozone Distribution Over Qatar

    NASA Astrophysics Data System (ADS)

    Ayoub, Mohammed; Ackermann, Luis

    2015-04-01

    We report on the vertical distribution and seasonal variability in tropospheric ozone over the Middle East through one year of weekly ozonesondes launched from Doha, Qatar during 2014. A total of 49 2Z-V7 DMT/EN-SCI Electrochemical Concentration Cell (ECC) ozonesondes employing a 1% buffered potassium iodide solution (KI), coupled with iMet-1-RS GPS radiosondes were launched around 1300 local time. The authors used the SkySonde telemetry software (developed by CIRES and NOAA/ESRL) and developed robust in-house data quality assurance and validation methodologies. The average height of the thermal tropopause is between 15-17.5 km (125-85 hPa). Monthly average relative humidity around the tropopause shows an enhancement during the months of June through the beginning of October. Monthly average temperature profiles show the development of the subtropical subsidence inversion around 5-6 km (450-520 hPa) between the months of April through October. The subsidence inversion is strongest during the months of June and July and is accompanied by a sharp drop in relative humidity over a 100-300 m in the vertical. The monthly average ozone background concentration between the Planetary Boundary Layer (PBL) height and the subsidence inversion increases from 50 ppb in the winter to almost 80 ppb in the summer months. An enhancement of up to 50% in the average ozone in the mid-to-upper troposphere (above the subsidence inversion) is strongest during the summer months (June through September) and results in average concentrations between 80-100 ppb. In the upper troposphere (above 13 km/200 hPa) ozone concentrations are highest during the spring and summer months. This is coupled with a drop in the average height of the tropopause. HYSPLIT back-trajectory analysis shows the enhancement in mid-to-upper tropospheric ozone in the summer is due to persistent high pressure over the Middle East between the months of June through September. Evidence of Stratosphere-Troposphere Exchange

  4. ICAM-1-independent, CD18-dependent adhesion between neutrophils and human epithelial cells exposed in vitro to ozone

    SciTech Connect

    Tosi, M.F.; Hamedani, A.; Brosovich, J.; Alpert, S.E. )

    1994-02-15

    Inhalant exposure to ozone can cause diffuse airway epithelial injury that is associated with an inflammatory response, including the influx of neutrophils into lung and airway tissue. The authors have previously documented enhanced adhesiveness by neutrophils for human airway epithelial cells in in vitro models of diseases associated with airway inflammation and have suggested that this enhanced adhesion may contribute to neutrophil-mediated airway injury. When primary human tracheal epithelial cell (TEC) monolayers were exposed to ozone at 2.0 ppm for 30 min or 0.5 ppm for 2 h, the percentage of PMN adhering to these cells increased from <5% to a maximum of approximately 75% by 18 to 24 h after the ozone exposure. No change was observed within the first 2 h after ozone exposure, but there was a statistically significant increase in PMN adhesion by 8 h after exposure. In contrast to previous studies with cytokine exposure or respiratory virus infection of TEC, the increased adhesion after ozone exposure was not associated with an increase in epithelial expression of ICAM-1. Consistent with the lack of induction of ICAM-1 by ozone exposure was the observation that anti-ICAM-1 mAbs previously shown to block PMN adhesion to TEC with increased ICAM-1 expression had no effect on PMN adhesion to ozone-exposed TEC. However, mAbs against CD11b or CD18 on PMN blocked PMN adhesion to ozone-exposed TEC by approximately 55 and 80%, respectively. Chemoattractant preactivation of PMN was necessary to achieve the highest levels of adhesion to ozone-treated TEC, in marked contrast to earlier studies with PMN adhesion to cytokine-treated or virus-infected TEC in which resting and prestimulated PMN exhibited the same high levels of adhesion.

  5. Analysis of atmospheric ozone levels at commercial airplane cruise altitudes in winter and spring 1976-77. Technical paper

    SciTech Connect

    Holdeman, J.D.; Nastrom, G.D.

    1981-04-01

    It has been speculated that the ozone sickness experienced by some airline passengers and crew members during the winter and spring of 1976-77 were induced by abnormally high concentrations of ambient atmospheric ozone. To investigate the possibility that 1976-77 was anomalous, ozone measurements from balloons for up to 13 years and from Global Atmospheric Sampling Program (GASP) equipped aircraft for 3 years have been studied. The analyses show that the winter and spring seasons of 1976-77 were averaged statistically, and no evidence was found to suggest that there was more than a usual variation in the frequency that commercial airplanes encountered high ambient ozone concentrations.

  6. Amazon basin ozone and aerosol: Wet season observations

    SciTech Connect

    Gregory, G.L.; Browell, E.V.; Warren, L.S.; Hudgins, C.H. )

    1990-09-20

    The tropical environment is recognized as having a major impact on global tropospheric chemistry. The data show that the wet season Amazon Basin is an effective sink for ozone and a net source for aerosols. Mixed layer ozone at 150-m altitude averaged 8.5 ppbv compared to about 18 ppbv at 3-km altitude. In addition, a negative ozone gradient (decreasing value to the surface) was observed within the mixed layer. The averaged wet season mixed layer ozone was about 7 ppbv lower than observed during the dry season. This is attributed to the enhanced convective activity associated with the wet season and the change in mixed layer photochemistry from net ozone production (dry season) to a net destruction (wet season). The net sink characteristics of the wet season mixed layer are seen throughout the troposphere of the Amazon Basin in that ozone (3- to 4-km altitude) is typically 15-25 ppbv as compared to dry season values of 30-35 ppbv. In terms of the aerosol source characteristics of the Amazon Basin, mixed layer aerosols (0.1- to 0.4-{mu}m diameter) are a factor of 5-10 higher than observed in the troposphere with mixed layer values of 100-200 aerosols/cm{sup 3}. Analyses of both tropospheric and mixed layer aerosol samples show aerosols which are multisource. Tropospheric samples have size distributions which are trimodal and show modes at aerosol diameters which suggest the aerosols are (1) of lifetimes <1 hour, (2) of lifetimes of days, and (3) mechanically generated elements (e.g., wind-blow dust). Mixed layer data show two of the three modes with no mode which represent aerosols with lifetimes of days.

  7. Elevation of susceptibility to ozone-induced acute tracheobronchial injury in transgenic mice deficient in Clara cell secretory protein

    SciTech Connect

    Plopper, C.G. . E-mail: cgplopper@ucdavis.edu; Mango, G.W.; Hatch, G.E.; Wong, V.J.; Toskala, E.; Reynolds, S.D.; Tarkington, B.K.; Stripp, B.R.

    2006-05-15

    Increases in Clara cell abundance or cellular expression of Clara cell secretory protein (CCSP) may cause increased tolerance of the lung to acute oxidant injury by repeated exposure to ozone (O{sub 3}). This study defines how disruption of the gene for CCSP synthesis affects the susceptibility of tracheobronchial epithelium to acute oxidant injury. Mice homozygous for a null allele of the CCSP gene (CCSP-/-) and wild type (CCSP+/+) littermates were exposed to ozone (0.2 ppm, 8 h; 1 ppm, 8 h) or filtered air. Injury was evaluated by light and scanning electron microscopy, and the abundance of necrotic, ciliated, and nonciliated cells was estimated by morphometry. Proximal and midlevel intrapulmonary airways and terminal bronchioles were evaluated. There was no difference in airway epithelial composition between CCSP+/+ and CCSP-/- mice exposed to filtered air, and exposure to 0.2 ppm ozone caused little injury to the epithelium of both CCSP+/+ and CCSP-/- mice. After exposure to 1.0 ppm ozone, CCSP-/- mice suffered from a greater degree of epithelial injury throughout the airways compared to CCSP+/+ mice. CCSP-/- mice had both ciliated and nonciliated cell injury. Furthermore, lack of CCSP was associated with a shift in airway injury to include proximal airway generations. Therefore, we conclude that CCSP modulates the susceptibility of the epithelium to oxidant-induced injury. Whether this is due to the presence of CCSP on the acellular lining layer surface and/or its intracellular distribution in the secretory cell population needs to be defined.

  8. Averaging Internal Consistency Reliability Coefficients

    ERIC Educational Resources Information Center

    Feldt, Leonard S.; Charter, Richard A.

    2006-01-01

    Seven approaches to averaging reliability coefficients are presented. Each approach starts with a unique definition of the concept of "average," and no approach is more correct than the others. Six of the approaches are applicable to internal consistency coefficients. The seventh approach is specific to alternate-forms coefficients. Although the…

  9. 35 state ozone transport region (OTAG) & ozone & PM NAAQS & regional HAZE FACA

    SciTech Connect

    Mathur, B.

    1996-11-01

    The activities of the 35 state ozone transport regions (OTAG) are summarized. Topics discussed include: the Chicago 15 percent plan; federal measures; VOC reduction goals; daily maximum ozone concentrations; ozone attainment demonstration policy; OTAG`s progress to date; significant upcoming activities; ozone transport assessment; model sensitivity analysis; FACA processes; and ozone, particulate matter, and regional haze implementation programs.

  10. Stratospheric ozone in the 21st Century: The chlorofluorocarbon problem

    SciTech Connect

    Rowland, F.S. )

    1991-04-01

    Ozone (O{sub 3}) exists in a dynamic equilibrium in the stratosphere, balanced between formation by solar ultraviolet photolysis ({lambda} < 242 nm) of molecular O{sub 2} (O + O{sub 2} {yields} O{sub 3}) and destruction by various chemical processes including several chain reaction sequences triggered by HO{sub x}, NO{sub x}, and ClO{sub x} radicals. The ozone dissipates over Antarctica by November through northward mixing, only to begin reappearing in late August of the following year. Substantial ozone losses have also appeared, although not as spectacularly as over Antarctica, in the Northern Hemisphere's temperate and polar regions. The primary cause for the Antarctic ozone loss, and the probable cause for the northern losses, is the increasing concentration in the stratosphere of anthropogenic chlorine, especially chlorine released by solar UV photolysis from chlorofluorocarbon (CFC) compounds such as CCl{sub 2}F{sub 2} (CFC-12), CCl{sub 3}F (CFC-11) and CCl{sub 2}FCClF{sub 2} (CFC-113). Because these molecules have average atmospheric lifetimes of many decades, excess anthropogenic chlorine will persist in the stratosphere for comparable time periods, and the Antarctic ozone hole will be an important atmospheric phenomenon throughout the 21st century.

  11. Persistence of the acute effects of ozone exposure

    SciTech Connect

    Folinsbee, L.J.; Horvath, S.M.

    1986-12-01

    Reexposure to ozone 24 h after an initial exposure results in greater decreases in forced expiratory tests of lung function following the second exposure. The purpose of this study was to determine whether this hyperresponsiveness was present earlier than 24 h or persisted beyond 24 h. Four groups of subjects (n = 6,6,7,7) were exposed to 0.25 ppm ozone and then reexposed at 12, 24, 48, or 72 h, respectively. During the 1-h exposures (Ta = 20 degrees C, RH = 70%) all subjects exercised continuously at approximately 65% of their respective peak VO2; VE averaged 63 L X min-1. The decrease in FEV1.0 after the second ozone exposure was significantly larger than that after the first for subjects reexposed at 12 or 24 h; FEV1.0 dropped 12% and 19% in the 12 h group, and 20% and 35% in the 24 h group. Subjects reexposed at 48 or 72 h had FEV1.0 responses which were not significantly different from the first exposure. Delta FEV1.0 on the first and second exposures were significantly correlated (r = 0.59). Symptoms generally paralleled changes in function. We conclude that the hyperresponsiveness to ozone following exposure to 0.25 ppm ozone under the conditions of this study is apparent within 12 h and is not present at 72 h.

  12. Assessing the public health benefits of reduced ozone concentrations.

    PubMed Central

    Levy, J I; Carrothers, T J; Tuomisto, J T; Hammitt, J K; Evans, J S

    2001-01-01

    In this paper we examine scientific evidence and related uncertainties in two steps of benefit-cost analyses of ozone reduction: estimating the health improvements attributable to reductions in ozone and determining the appropriate monetary values of these improvements. Although substantial evidence exists on molecular and physiologic impacts, the evidence needed to establish concentration-response functions is somewhat limited. Furthermore, because exposure to ozone depends on factors such as air conditioning use, past epidemiologic studies may not be directly applicable in unstudied settings. To evaluate the evidence likely to contribute significantly to benefits, we focus on four health outcomes: premature mortality, chronic asthma, respiratory hospital admissions, and minor restricted activity days. We determine concentration-response functions for these health outcomes for a hypothetical case study in Houston, Texas, using probabilistic weighting reflecting our judgment of the strength of the evidence and the possibility of confounding. We make a similar presentation for valuation, where uncertainty is due primarily to the lack of willingness-to-pay data for the population affected by ozone. We estimate that the annual monetary value of health benefits from reducing ozone concentrations in Houston is approximately $10 per person per microgram per cubic meter (24-hr average) reduced (95% confidence interval, $0.70-$40). The central estimate exceeds past estimates by approximately a factor of five, driven by the inclusion of mortality. We discuss the implications of our findings for future analyses and determine areas of research that might help reduce the uncertainties in benefit estimation. PMID:11748028

  13. Nitroaromatic hydrocarbon ozonation in water. 1: Single ozonation

    SciTech Connect

    Beltran, F.J.; Encinar, J.M.; Alonso, M.A.

    1998-01-01

    Single ozonation of two nitroaromatic hydrocarbons (nitrobenzene and 2,6-dinitrotoluene) under different experimental conditions (ozone feed rate, pH, temperature, hydroxyl radical scavengers) has been studied. The absence of hydroxyl radical scavengers, pHs 7--9, and temperatures below 30 C are optimum conditions for nitroaromatic removal. Due to the importance of hydroxyl radical reactions, removal rates in natural water are much lower than those observed in laboratory ultrapure water. Rate constants of the direct reaction between ozone and nitroaromatic hydrocarbons at 20 C have been found to be lower than 6 M{sup {minus}1} s{sup {minus}1}. More than 99% of nitroaromatic removal is due to hydroxyl radical oxidation. Single ozonation of nitroaromatics can then be classified as a real advanced oxidation technology. Nitrophenols, compounds very reactive toward ozone and hydroxyl radicals, and 2,6-dinitrobenzaldehyde, identified in the single ozonation of nitrobenzene and 2,6-dinitrotoluene, respectively, are some of the first intermediates of single ozonation.

  14. Validation of OMI Total Ozone Retrievals from the SAO Ozone Profile Algorithm and Three Operational Algorithms 3 with Brewer Measurements

    NASA Astrophysics Data System (ADS)

    Bak, Juseon; Kim, Jae H.; Liu, Xiong; Chance, Kelly

    2015-04-01

    The optimal estimation (OE) based ozone profile algorithm developed at Smithsonian 3 Astrophysical Observatory (SAO) is assessed as to its accuracy to extract total ozone amount from 4 Ozone Monitoring Instrument (OMI) measurements through the validation using Brewer ground 5 based measurements between January 2005 and December 2008. We compare it against the quality of 6 three OMI operational ozone products, derived from NASA TOMS, KNMI DOAS, and KNMI OE 7 algorithms, respectively. The validation demonstrates that the SAO ozone profile algorithm generally 8 has the best total ozone retrieval performance compared to the three OMI operational ozone products. 9 The individual station comparisons show an agreement between SAO and Brewer within ± 1% except 10 at polar stations (~ -2 %), with a high correlation coefficient of ~ 0.99 at most stations. The KNMI OE 11 algorithm systematically overestimates the true total ozone value at all stations with a bias from 2 % 12 at low/mid latitude stations to 5 % at high latitude stations. On the other hand, TOMS/DOAS 13 algorithm underestimates total ozone by ~ -1.7 % on average. The standard deviations of differences 14 are ~ 1.8 % for SAO and TOMS while DOAS and KNMI show the standard deviation values of 2.2 15 and 2.5 %, respectively. The remarkable stability of SAO OE algorithm is found with no significant 16 dependency on algorithmic variables such as viewing geometries, cloud parameters, and time. In 17 comparison, the severe dependency on both solar and viewing zenith angles is found in KNMI OE 18 algorithm, which is characterized with a negative (positive) correlation with smaller (larger) solar 19 zenith angles and the strong cross-track dependent biases ranging from 4% at nadir and 1% at off-20 nadir positions. The dependence of DOAS and TOMS algorithms on the algorithmic variables is 21 marginal compared to KNMI OE algorithm, but distinct compared to SAO OE algorithm. Relative 22 differences between SAO/DOAS and

  15. Southern Hemisphere Additional Ozonesondes (SHADOZ) Ozone Climatology (2005-2009): Tropospheric and Tropical Tropopause Layer (TTL) Profiles with Comparisons to Omi-based Ozone Products

    NASA Technical Reports Server (NTRS)

    Thompson, Anne M.; Miller, Sonya K.; Tilmes, Simone; Kollonige, Debra W.; Witte, Jacquelyn C.; Oltmans, Samuel J.; Johnson, Brian J.; Fujiwara, Masatomo; Schmidlin, F. J.; Coetzee, G. J. R.; Komala, Ninong; Maata, Matakite; bt Mohammad, Maznorizan; Nguyo, J.; Mutai, C.; Ogino, S-Y; Da Silva, F. Raimundo; Paes Leme, N. M.; Posny, Francoise; Scheele, Rinus; Selkirk, Henry B.; Shiotani, Masato; Stubi, Rene; Levrat, Gilbert; Calpini, Bertrand; Thouret, Valerie; Tsuruta, Haruo; Canossa, Jessica Valverde; Voemel, Holger; Yonemura, S.; Andres Diaz, Jorge; Tan Thanh, Nguyen T.; Thuy Ha, Hoang T.

    2012-01-01

    We present a regional and seasonal climatology of SHADOZ ozone profiles in the troposphere and tropical tropopause layer (TTL) based on measurements taken during the first five years of Aura, 2005-2009, when new stations joined the network at Hanoi, Vietnam; Hilo, Hawaii; Alajuela Heredia, Costa Rica; Cotonou, Benin. In all, 15 stations operated during that period. A west-to-east progression of decreasing convective influence and increasing pollution leads to distinct tropospheric ozone profiles in three regions: (1) western Pacific eastern Indian Ocean; (2) equatorial Americas (San Cristobal, Alajuela, Paramaribo); (3) Atlantic and Africa. Comparisons in total ozone column from soundings, the Ozone Monitoring Instrument (OMI, on Aura, 2004-) satellite and ground-based instrumentation are presented. Most stations show better agreement with OMI than they did for EPTOMS comparisons (1998-2004; Earth-ProbeTotal Ozone Mapping Spectrometer), partly due to a revised above-burst ozone climatology. Possible station biases in the stratospheric segment of the ozone measurement noted in the first 7 years of SHADOZ ozone profiles are re-examined. High stratospheric bias observed during the TOMS period appears to persist at one station. Comparisons of SHADOZ tropospheric ozone and the daily Trajectory-enhanced Tropospheric Ozone Residual (TTOR) product (based on OMIMLS) show that the satellite-derived column amount averages 25 low. Correlations between TTOR and the SHADOZ sondes are quite good (typical r2 0.5-0.8), however, which may account for why some published residual-based OMI products capture tropospheric interannual variability fairly realistically. On the other hand, no clear explanations emerge for why TTOR-sonde discrepancies vary over a wide range at most SHADOZ sites.

  16. The Average of Rates and the Average Rate.

    ERIC Educational Resources Information Center

    Lindstrom, Peter

    1988-01-01

    Defines arithmetic, harmonic, and weighted harmonic means, and discusses their properties. Describes the application of these properties in problems involving fuel economy estimates and average rates of motion. Gives example problems and solutions. (CW)

  17. Total ozone changes in the 1987 Antarctic ozone hole

    NASA Technical Reports Server (NTRS)

    Krueger, Arlin J.; Schoeberl, Mark R.; Doiron, Scott D.; Sechrist, Frank; Galimore, Reginald

    1988-01-01

    The development of the Antarctic ozone minimum was observed in 1987 with the Nimbus 7 Total Ozone Mapping Spectrometer (TOMS) instrument. In the first half of August the near-polar (60 and 70 deg S) ozone levels were similar to those of recent years. By September, however, the ozone at 70 and 80 deg S was clearly lower than any previous year including 1985, the prior record low year. The levels continued to decrease throughout September until October 5 when a new record low of 109 DU was established at a point near the South Pole. This value is 29 DU less than the lowest observed in 1985 and 48 DU less than the 1986 low. The zonal mean total ozone at 60 deg S remained constant throughout the time of ozone hole formation. The ozone decline was punctuated by local minima formed away from the polar night boundary at about 75 deg S. The first of these, on August 15 to 17, formed just east of the Palmer Peninsula and appears to be a mountain wave. The second major minimum formed on September 5 to 7 again downwind of the Palmer Peninsula. This event was larger in scale than the August minimum and initiated the decline of ozone across the polar region. The 1987 ozone hole was nearly circular and pole centered for its entire life. In previous years the hole was perturbed by intrusions of the circumpolar maximum into the polar regions, thus causing the hole to be elliptical. The 1987 hole also remained in place until the end of November, a few days longer than in 1985, and this persistence resulted in the latest time for recovery to normal values yet observed.

  18. Southern African Ozone Trends (1990-2007): Influences of Climate Variability and Anthropogenic Sources

    NASA Astrophysics Data System (ADS)

    Thompson, A. M.; Balashov, N. V.; Witte, J. C.; Piketh, S.; Coetzee, G. J.; Thouret, V.

    2014-12-01

    Studies of tropospheric ozone trends over the southern African Highveld in the 1990-2007 period present a paradox. We used monthly averaged surface ozone data from 5 South African monitoring stations east of Johannesburg in a linear regression model to show that the cycles associated with the El Niño/La Niña make a considerable contribution to interannual ozone variability through perturbations in cloud cover, temperature and precipitation that interact with photochemistry (see Figure). During El Niño periods, typically sunnier and drier, summertime ozone is enhanced, whereas wetter, cloudier conditions of a La Niña are associated with lower ozone. Interestingly, the 5 stations show very little evidence of a statistically significant trend from 1990 through 2007. Over the same time period, the regression model shows that free tropospheric ozone, from 5-11 km, taken from monthly averaged SHADOZ (Southern Hemisphere ADditional OZonesondes) and MOZAIC (Measurement of Ozone and Water Vapour on Airbus in-service Aircraft) profiles, increased significantly (+20-25%/decade) in late autumn and early winter (May-July). There is also a positive ozone trend near the tropopause in summer (Nov.-Dec.) but none during the oft-studied months of biomass fires (Sept.-Oct.). It is difficult to interpret the seemingly contradictory trends in terms of emissions of ozone precursors that are not well characterized over the Highveld and larger southern African region. However, we ran a series of back-trajectories at 500 and 300 hPa to coincide with the profile sampling times in May-August 1990-2007. Regional contributions are implicated by recirculation in the Johannesburg region. Trajectories also point to long-range transport from the greater African continent, south Atlantic and South America, all known regions of high ozone and in the case of South America, growing pollution from emerging mega-cities.

  19. Is the Ozone Hole over Your Classroom?

    ERIC Educational Resources Information Center

    Cordero, Eugene C.

    2002-01-01

    Reports on a survey of first year university science students regarding their understanding of the ozone layer, ozone depletion, and the effect of ozone depletion on Australia. Suggests that better teaching resources for environmental issues such as ozone depletion and global warming are needed before improvements in student understanding can be…

  20. Improved western U.S. background ozone estimates via constraining nonlocal and local source contributions using Aura TES and OMI observations

    NASA Astrophysics Data System (ADS)

    Huang, Min; Bowman, Kevin W.; Carmichael, Gregory R.; Lee, Meemong; Chai, Tianfeng; Spak, Scott N.; Henze, Daven K.; Darmenov, Anton S.; Silva, Arlindo M.

    2015-04-01

    Western U.S. near-surface ozone (O3) concentrations are sensitive to transported background O3 from the eastern Pacific free troposphere, as well as U.S. anthropogenic and natural emissions. The current 75 ppbv U.S. O3 primary standard may be lowered soon, hence accurately estimating O3 source contributions, especially background O3 in this region has growing policy-relevant significance. In this study, we improve the modeled total and background O3, via repartitioning and redistributing the contributions from nonlocal and local anthropogenic/wildfires sources in a multi-scale satellite data assimilation system containing global Goddard Earth Observing System-Chemistry model (GEOS-Chem) and regional Sulfur Transport and dEposition Model (STEM). Focusing on NASA's ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) field campaign period in June-July 2008, we first demonstrate that the negative biases in GEOS-Chem free simulation in the eastern Pacific at 400-900 hPa are reduced via assimilating Aura-Tropospheric Emission Spectrometer (TES) O3 profiles. Using the TES-constrained boundary conditions, we then assimilated into STEM the tropospheric nitrogen dioxide (NO2) columns from Aura-Ozone Monitoring Instrument to indicate U.S. nitrogen oxides (NOx = NO2 + NO) emissions at 12 × 12 km2 grid scale. Improved model skills are indicated from cross validation against independent ARCTAS measurements. Leveraging Aura observations, we show anomalously high wildfire NOx emissions in this summer in Northern California and the Central Valley while lower anthropogenic emissions in multiple urban areas than those representing the year of 2005. We found strong spatial variability of the daily maximum 8 h average background O3 and its contribution to the modeled total O3, with the mean value of ~48 ppbv (~77% of the total).

  1. Influence of Emissions from Oil and Gas Development on Elevated Ozone in the Northern Colorado Front Range

    NASA Astrophysics Data System (ADS)

    Evans, J. M.; Helmig, D.; Thompson, C. R.

    2014-12-01

    The Northern Colorado Front Range (NCFR) region has been in exceedance of the ozone National Ambient Air Quality Standard (NAAQS) since 2004. Rapidly growing oil and natural gas (O&NG) operations in the Denver-Julesberg Basin, NNE of the Denver metropolitan area, continue to be one of the largest volatile organic compound emitting sources in the region. Trend analysis of the last 13 years of Denver/NCFR ozone monitoring from five sites does not show any statistically significant decrease in annual regulated ozone maxima despite state efforts to mitigate ozone precursor emissions. In this work, we investigate the contribution of O&NG emissions to continued exceedances of the ozone NAAQS. We use surface ozone and wind data from two sites near Boulder, Colorado, to investigate the climatology of ozone in the NCFR region. Transport analyses show a preponderance of elevated ozone events associated with transport from the O&NG operations area in the N-ESE sector, rather than from the more densely populated Denver metro area to the SE-S. On average, between the two sites, air transport from areas associated with dense O&NG operations accounts for 65% of 1-hr averaged elevated ozone (>75 ppbv), while transport from the densely populated Denver metropolitan area accounts for only 9%.

  2. A statistical modeling framework for projecting future ambient ozone and its health impact due to climate change

    NASA Astrophysics Data System (ADS)

    Chang, Howard H.; Hao, Hua; Sarnat, Stefanie Ebelt

    2014-06-01

    The adverse health effects of ambient ozone are well established. Given the high sensitivity of ambient ozone concentrations to meteorological conditions, the impacts of future climate change on ozone concentrations and its associated health effects are of concern. We describe a statistical modeling framework for projecting future ozone levels and its health impacts under a changing climate. This is motivated by the continual effort to evaluate projection uncertainties to inform public health risk assessment. The proposed approach was applied to the 20-county Atlanta metropolitan area using regional climate model (RCM) simulations from the North American Regional Climate Change Assessment Program. Future ozone levels and ozone-related excesses in asthma emergency department (ED) visits were examined for the period 2041-2070. The computationally efficient approach allowed us to consider 8 sets of climate model outputs based on different combinations of 4 RCMs and 4 general circulation models. Compared to the historical period of 1999-2004, we found consistent projections across climate models of an average 11.5% higher ozone levels (range: 4.8%, 16.2%), and an average 8.3% (range: -7%-24%) higher number of ozone exceedance days. Assuming no change in the at-risk population, this corresponds to excess ozone-related ED visits ranging from 267 to 466 visits per year. Health impact projection uncertainty was driven predominantly by uncertainty in the health effect association and climate model variability. Calibrating climate simulations with historical observations reduced differences in projections across climate models.

  3. Corona discharge influences ozone concentrations near rats.

    PubMed

    Goheen, Steven C; Gaither, Kari; Anantatmula, Shantha M; Mong, Gary M; Sasser, Lyle B; Lessor, Delbert

    2004-02-01

    Ozone can be produced by corona discharge either in dry air or when one electrode is submerged in water. Since ozone is toxic, we examined whether ozone production by corona near laboratory animals could reach levels of concern. Male rats were exposed to a corona discharge and the concentration of ozone produced was measured. The resulting concentration of ozone ranged from ambient levels to 250 ppb when animals were located 1 cm from a 10 kV source. Similar ozone concentrations were observed when a grounded water source was present. Possible explanations for, as well as concerns regarding, ozone production under these conditions are discussed. PMID:14735560

  4. When will Antarctic ozone begin to recover?

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-01-01

    Emissions of ozone-depleting substances have declined over recent decades, but it takes time for the ozone layer to recover. Regular measurements of ozone levels above the South Pole now stretch back 25 years. Hassler et al. analyzed these recorded ozone data to assess changes in ozone loss rates. Consistent with previous studies, they found that ozone loss rates have been stable over the past 15 years, neither increasing nor decreasing. However, they predict that, assuming future atmospheric dynamics are similar to today's, ozone loss rates will begin to decline noticeably between 2017 and 2021. (Journal of Geophysical Research-Atmospheres, doi:10.1029/2011JD016353, 2011)

  5. Transport effects on the vertical distribution of tropospheric ozone over western India

    NASA Astrophysics Data System (ADS)

    Lal, S.; Venkataramani, S.; Chandra, N.; Cooper, O. R.; Brioude, J.; Naja, M.

    2014-08-01

    In situ tropospheric ozone measurements by balloon-borne electrochemical concentration cell (ECC) sensors above Ahmedabad in western India from May 2003 to July 2007 are presented, along with an analysis of the transport processes responsible for the observed vertical ozone distribution. This analysis is supported by 12 day back trajectory calculations using the FLEXPART Lagrangian particle dispersion model. Lowest ozone (~20 ppbv) is observed near the surface during September at the end of the Asian summer monsoon season. Average midtropospheric (5-10 km above sea level) ozone is greatest (70-75 ppbv) during April-June and lowest (40-50 ppbv) during winter. Ozone variability is greatest in the upper troposphere with higher ozone during March-May. The FLEXPART retroplume results show that the free tropospheric vertical ozone distribution above this location is affected by long-range transport from the direction of North Africa and North America. Ozone levels are also affected by transport from the stratosphere particularly during March-April. The lower tropospheric (<3 km) ozone distribution during the Asian summer monsoon is affected by transport from the Indian Ocean via the east coast of Africa and the Arabian Sea. Influence from deep convection in the upper troposphere confined over central Asia has been simulated by FLEXPART. Lower ozone levels are observed during August-November than in any other season at 10-14 km above sea level. These in situ observations are in contrast to other studies based on satellite data which show that the lowest ozone values at these altitudes occur during the Asian summer monsoon.

  6. The potential near-source ozone impacts of upstream oil and gas industry emissions.

    PubMed

    Olaguer, Eduardo P

    2012-08-01

    Increased drilling in urban areas overlying shale formations and its potential impact on human health through decreased air quality make it important to estimate the contribution of oil and gas activities to photochemical smog. Flares and compressor engines used in natural gas operations, for example, are large sources not only of NOx but also offormaldehyde, a hazardous air pollutant and powerful ozone precursor We used a neighborhood scale (200 m horizontal resolution) three-dimensional (3D) air dispersion model with an appropriate chemical mechanism to simulate ozone formation in the vicinity ofa hypothetical natural gas processing facility, based on accepted estimates of both regular and nonroutine emissions. The model predicts that, under average midday conditions in June, regular emissions mostly associated with compressor engines may increase ambient ozone in the Barnett Shale by more than 3 ppb beginning at about 2 km downwind of the facility, assuming there are no other major sources of ozone precursors. Flare volumes of 100,000 cubic meters per hour ofnatural gas over a period of 2 hr can also add over 3 ppb to peak 1-hr ozone somewhatfurther (>8 km) downwind, once dilution overcomes ozone titration and inhibition by large flare emissions of NOx. The additional peak ozone from the hypothetical flare can briefly exceed 10 ppb about 16 km downwind. The enhancements of ambient ozone predicted by the model are significant, given that ozone control strategy widths are of the order of a few parts per billion. Degrading the horizontal resolution of the model to 1 km spuriously enhances the simulated ozone increases by reducing the effectiveness of ozone inhibition and titration due to artificial plume dilution. PMID:22916444

  7. Balloon-borne observations of the development and vertical structure of the Antarctic ozone hole in 1986

    NASA Technical Reports Server (NTRS)

    Hofmann, D. J.; Harder, J. W.; Rolf, S. R.; Rosen, J. M.

    1987-01-01

    The vertical distribution of ozone measured at McMurdo Station, Antarctica using balloon-borne sensors on 33 occasions during November 6, 1986 - August 25, 1986 is described. These observations suggest a highly structured cavity confined to the 12-20 km altitude region. In the 17-19 km altitude range, the ozone volume mixing ratio declined from about 2 ppm at the end of August to about 0.5 ppm by mid-October. The average decay in this region can be described as exponential with a half life of about 25 days. While total ozone, as obtained from profile integration, declined only about 35 percent, the integrated ozone between 14 and 18 km declined more than 70 percent. Vertical ozone profiles in the vortex revealed unusual structure with major features from 1 to 5 km thick which had suffered ozone depletions as great as 90 percent.

  8. Airborne measurements of stratospheric constituents over Antarctica in the austral spring 1987. I - Method and ozone observations

    NASA Technical Reports Server (NTRS)

    Mankin, William G.; Coffey, M. T.

    1989-01-01

    A Fourier transform spectrometer was flown aboard a DC-8 on 10 flights over Antarctica during August and September, 1987, as part of the Airborne Antarctic Ozone Experiment (AAOE). Observing the sun at infrared wavelengths, it was possible to determine the integrated column amount above the flight altitude for ozone and a number of other chemical species that are believed to be important in the perturbed chemistry of the 'ozone hole'. The paper describes the method, the observations, the data analysis procedure, and the ozone results. During the observation period, ozone developed a steep gradient near the edge of the polar vortex; deep within the vortex, the average ozone column decreased by about 1.6 percent per day during September.

  9. Unprecedented Arctic ozone loss in 2011.

    PubMed

    Manney, Gloria L; Santee, Michelle L; Rex, Markus; Livesey, Nathaniel J; Pitts, Michael C; Veefkind, Pepijn; Nash, Eric R; Wohltmann, Ingo; Lehmann, Ralph; Froidevaux, Lucien; Poole, Lamont R; Schoeberl, Mark R; Haffner, David P; Davies, Jonathan; Dorokhov, Valery; Gernandt, Hartwig; Johnson, Bryan; Kivi, Rigel; Kyrö, Esko; Larsen, Niels; Levelt, Pieternel F; Makshtas, Alexander; McElroy, C Thomas; Nakajima, Hideaki; Parrondo, Maria Concepción; Tarasick, David W; von der Gathen, Peter; Walker, Kaley A; Zinoviev, Nikita S

    2011-10-27

    Chemical ozone destruction occurs over both polar regions in local winter-spring. In the Antarctic, essentially complete removal of lower-stratospheric ozone currently results in an ozone hole every year, whereas in the Arctic, ozone loss is highly variable and has until now been much more limited. Here we demonstrate that chemical ozone destruction over the Arctic in early 2011 was--for the first time in the observational record--comparable to that in the Antarctic ozone hole. Unusually long-lasting cold conditions in the Arctic lower stratosphere led to persistent enhancement in ozone-destroying forms of chlorine and to unprecedented ozone loss, which exceeded 80 per cent over 18-20 kilometres altitude. Our results show that Arctic ozone holes are possible even with temperatures much milder than those in the Antarctic. We cannot at present predict when such severe Arctic ozone depletion may be matched or exceeded. PMID:21964337

  10. Influence of wildfires on the variability and trend of ozone concentrations in the U.S. Intermountain West

    NASA Astrophysics Data System (ADS)

    Lu, Xiao; Zhang, Lin; Zhao, Yuanhong; Yue, Xu

    2016-04-01

    Wildfires are important sources of ozone by emitting large amounts of NOx and NMVOC, main ozone precursors at both global and regional scales. Their influences on ozone in the U.S. Intermountain West have recently received much interest because surface ozone concentrations over that region showed an increasing trend in the past two decades likely due to increasing wildfire emissions in a warming climate. Here we use the Lagrangian particle dispersion model (FLEXPART) as well as the GEOS-Chem chemical transport model to estimate wildfires' contribution on summer (June, July and August; JJA) ozone concentration variations, trends, and extremely high ozone events over the US Intermountain West for the past 22 years (1989-2010). We combine the resident time estimated from the FLEXPART 5-day backward trajectories and a high-resolution fire inventory to define a fire index representing the impact of wildfires on ozone concentration at a particular site for each day of summers 1989-2010. Over 26,000 FLEXPART back-trajectories are conducted for the whole time period and for 13 CASTNet surface monitoring sites. We build a stepwise multiple linear regression (SMLR) model of daily ozone concentrations using fire index and other meteorological variables for each site. The SMLR models explain 53% of the ozone variations (ranging from 12% to 68% for each site). We show that ozone produced from wildfires (calculated from SMLR model) are of high variability at daily scale (ranging from 0.1 ppbv to 20.7 ppbv), but are averaged to lower values of about 0.25-3.5 ppbv for summer mean. We estimate that wildfires magnify inter-annual variations of the regional mean summer ozone for about 32%, compared to the result with wildfires impact excluded from the SMLR model. Wildfire ozone enhancements increase at a rate of 0.04 ppbv per year, accouting for about 20% of the regional summer ozone trend during 1989-2010. Removing wildfires' impact would reduce 35% (46%) of the high-ozone days with

  11. Northern middle-latitude ozone profile features and trends observed by SBUV and Umkehr, 1979-1990

    NASA Technical Reports Server (NTRS)

    Deluisi, J. J.; Mateer, C. L.; Theisen, D.; Bhartia, P. K.; Longenecker, D.; Chu, B.

    1994-01-01

    A comparison of Umkehr ozone profile data with the reprocessed solar backscatter ultraviolet (SBUV) ozone data in the northern middle-latitude region, 30 deg to 50 deg N, is reported. Although significant biases exist between the two types of observations, the long-term variations and least squares linear regression trends agree remarkably well over the comparison period of 1979 to 1990. The ozone trend in the upper stratosphere is of the order of -0.9%/yr. Near 25 km, little if any trend appears, but a larger negative trend is seen in the lower stratosphere near 15 km. Comparisons show that the average annual ozone cycles in the profiles also agree well. The upper stratospheric ozone results are consistent with photochemical model predictions of ozone depletion near 40 km that are due to the release of anthropogenically produced chlorofluorocarbons. The lower stratospheric ozone trend results are in reasonable agreement with published ozonesonde data trends. It is shown that the ozone trends in the lower stratospheric layers impact significantly on the total ozone trend of the order of -0.47%/yr. The good agreement now seen between the two types of observations suggest that the combined ground-based and satellite approach could provide a valuable database for long-term monitoring of stratospheric ozone for trends and extraordinary variations.

  12. The study of ozone variations in the Las Vegas metropolitan area using remote sensing information and ground observations

    USGS Publications Warehouse

    Xian, G.; Crane, M.

    2006-01-01

    Urban development in the Las Vegas Valley, Nevada, has grown rapidly in the past fifty years. Associated with this growth has been a change in landscape from natural cover types to developed urban land mixed with planned vegetation canopy throughout in the metropolitan area. Air quality in the Las Vegas Valley has been affected by increases in anthropogenic emissions and concentrations of carbon monoxide, ozone, and criteria pollutants of particular matter. Ozone concentration in the region is generally influenced by synoptic and mesoscale meteorological conditions, as well as regional transport of pollutants from the western side of Las Vegas. Local influences from ground-level nitrogen oxide emissions and vegetation canopy coverage also affect ozone concentration. Multi-year observational data collected by a network of local air monitoring stations in Clark County, Nevada, indicate that ozone maximums develop in May and June, while minimums exist primarily from November to February. Ozone concentrations are high on the west and northwest sides of the valley. A nighttime ozone reduction in the urban area characterizes the heterogeneous features of spatial distribution for average ozone levels in the Las Vegas urban area. The urban vegetation canopy has a locally positive effect by reducing ozone in urban areas. Decreased ozone levels associated with increased urban development density suggests that the highest ozone concentrations are associated with medium- to low-density urban development in Las Vegas.

  13. Photochemical roles of rapid economic growth and potential abatement strategies on tropospheric ozone over South and East Asia in 2030

    NASA Astrophysics Data System (ADS)

    Chatani, S.; Amann, M.; Goel, A.; Hao, J.; Klimont, Z.; Kumar, A.; Mishra, A.; Sharma, S.; Wang, S. X.; Wang, Y. X.; Zhao, B.

    2014-09-01

    A regional air quality simulation framework including the Weather Research and Forecasting modeling system (WRF), the Community Multi-scale Air Quality modeling system (CMAQ), and precursor emissions to simulate tropospheric ozone over South and East Asia is introduced. Concentrations of tropospheric ozone and related species simulated by the framework are validated by comparing with observation data of surface monitoring, ozonesondes, and satellites obtained in 2010. The simulation demonstrates acceptable performance on tropospheric ozone over South and East Asia at regional scale. Future energy consumption, carbon dioxide (CO2), nitrogen oxides (NOx), and volatile organic compound (VOC) emissions in 2030 under three future scenarios are estimated. One of the scenarios assumes a business-as-usual (BAU) pathway, and other two scenarios consider implementation of additional energy and environmental strategies to reduce energy consumption, CO2, NOx, and VOC emissions in China and India. Future surface ozone under these three scenarios is predicted by the simulation. The simulation indicates future surface ozone significantly increases around India for a whole year and around northeastern China in summer. NOx is a main driver on significant seasonal increase of surface ozone, whereas VOC as well as increasing background ozone and methane is also an important factor on annual average of surface ozone in East Asia. Warmer weather around India is also preferable for significant increase of surface ozone. Additional energy and environmental strategies assumed in future scenarios are expected to be effective to reduce future surface ozone over South and East Asia.

  14. Principal Component Analysis of Chlorophyll Content in Tobacco, Bean and Petunia Plants Exposed to Different Tropospheric Ozone Concentrations

    NASA Astrophysics Data System (ADS)

    Borowiak, Klaudia; Zbierska, Janina; Budka, Anna; Kayzer, Dariusz

    2014-06-01

    Three plant species were assessed in this study - ozone-sensitive and -resistant tobacco, ozone-sensitive petunia and bean. Plants were exposed to ambient air conditions for several weeks in two sites differing in tropospheric ozone concentrations in the growing season of 2009. Every week chlorophyll contents were analysed. Cumulative ozone effects on the chlorophyll content in relation to other meteorological parameters were evaluated using principal component analysis, while the relation between certain days of measurements of the plants were analysed using multivariate analysis of variance. Results revealed variability between plant species response. However, some similarities were noted. Positive relations of all chlorophyll forms to cumulative ozone concentration (AOT 40) were found for all the plant species that were examined. The chlorophyll b/a ratio revealed an opposite position to ozone concentration only in the ozone-resistant tobacco cultivar. In all the plant species the highest average chlorophyll content was noted after the 7th day of the experiment. Afterwards, the plants usually revealed various responses. Ozone-sensitive tobacco revealed decrease of chlorophyll content, and after few weeks of decline again an increase was observed. Probably, due to the accommodation for the stress factor. While during first three weeks relatively high levels of chlorophyll contents were noted in ozone-resistant tobacco. Petunia revealed a slow decrease of chlorophyll content and the lowest values at the end of the experiment. A comparison between the plant species revealed the highest level of chlorophyll contents in ozone-resistant tobacco.

  15. A Bayesian model for quantifying the change in mortality associated with future ozone exposures under climate change.

    PubMed

    Alexeeff, Stacey E; Pfister, Gabriele G; Nychka, Doug

    2016-03-01

    Climate change is expected to have many impacts on the environment, including changes in ozone concentrations at the surface level. A key public health concern is the potential increase in ozone-related summertime mortality if surface ozone concentrations rise in response to climate change. Although ozone formation depends partly on summertime weather, which exhibits considerable inter-annual variability, previous health impact studies have not incorporated the variability of ozone into their prediction models. A major source of uncertainty in the health impacts is the variability of the modeled ozone concentrations. We propose a Bayesian model and Monte Carlo estimation method for quantifying health effects of future ozone. An advantage of this approach is that we include the uncertainty in both the health effect association and the modeled ozone concentrations. Using our proposed approach, we quantify the expected change in ozone-related summertime mortality in the contiguous United States between 2000 and 2050 under a changing climate. The mortality estimates show regional patterns in the expected degree of impact. We also illustrate the results when using a common technique in previous work that averages ozone to reduce the size of the data, and contrast these findings with our own. Our analysis yields more realistic inferences, providing clearer interpretation for decision making regarding the impacts of climate change. PMID:26302149

  16. Surface level measurements of ozone and precursors at coastal and offshore locations in the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Ray, John D.; Heavner, Ron L.; Flores, Miguel; Michaelsen, Clifton W.

    1996-12-01

    The northeastern United States has episodic high ozone several times each year at locations remote from urban and industrial centers. Extended measurements of ozone and the ozone precursors, volatile organic compounds (VOC) and nitrogen oxides, were made at Acadia National Park, Cape Elizabeth, and other coastal Maine locations during the North Atlantic Regional Experiment (NARE) intensive. In addition, ozone was measured from a commercial ferry, the Scotia Prince, in the Gulf of Maine where ozone concentrations up to 129 ppb were observed. Two high-ozone episodes were observed during late August 1993 when ozone was greater than 90 ppb along much of the Maine coast. NOy concentrations at Acadia averaged 2.0 ppb (±1.97), maximum 12.0 ppb. During the high-ozone episodes, NOy had linear relationships to ozone with slopes of 4-16. The timing of maximum values and extent of the high-ozone air mass suggests that urban plumes transported over the Gulf of Maine are brought inland by sea breezes to the coastal regions but not to the interior areas of Maine.

  17. The Averaging Problem in Cosmology

    NASA Astrophysics Data System (ADS)

    Paranjape, Aseem

    2009-06-01

    This thesis deals with the averaging problem in cosmology, which has gained considerable interest in recent years, and is concerned with correction terms (after averaging inhomogeneities) that appear in the Einstein equations when working on the large scales appropriate for cosmology. It has been claimed in the literature that these terms may account for the phenomenon of dark energy which causes the late time universe to accelerate. We investigate the nature of these terms by using averaging schemes available in the literature and further developed to be applicable to the problem at hand. We show that the effect of these terms when calculated carefully, remains negligible and cannot explain the late time acceleration.

  18. Brewer Umkehr ozone profile retrievals

    NASA Astrophysics Data System (ADS)

    Petropavlovskikh, I. V.; Disterhoft, P.; Lantz, K. O.; Bhartia, P. K.; McPeters, R. D.; Flynn, L. E.; Oltmans, S. J.; Johnson, B. J.; Stanek, M.

    2011-12-01

    The Dobson Umkehr network has been a key data set for stratospheric ozone trend calculations (WMO Ozone assessments) and has earned its place as a benchmark network for stratospheric ozone profile observations. The Umkehr data has also been used to provide a long-term reference to the merging of the satellite ozone records (MOD), estimate the seasonal influence of an 11-year solar signal in the vertical distribution of stratospheric ozone, and to assess the ability of several remote and in-situ sensing systems in capturing ozone variability. It was found that Dobson Umkehr measurement errors were often comparable to errors derived for satellite and ozone-sounding methods. The Umkehr measurements are also available from the Brewer spectrophotometers [McElroy et al., 1995]. In 2005, the Dobson Umkehr algorithm (UMK04) was modified to retrieve ozone profile data from Brewer Umkehr measurements taken at two spectral channels [Petropavlovskikh et al, 2011]. The PC version of the Brewer algorithm was developed by M. Stanek (IOC, Canada and Czech Republic Meteorological Institute) in close collaboration with I. Petropavlovskikh. It was implemented at the NEUBrew network for operational processing of Umkehr data retrieved daily for all operational sites. The most recently developed Brewer ozone retrieval algorithm (MSBU) utilizes measurements that are currently available from the operational Brewer instruments. Umkehr measurements at multiple wavelength channels (similar to the satellite BUV method) and significantly reduced range of solar zenith angle are used for the twice a day operational ozone profile retrievals. Intercomparisons against ozone climatology, sounding, satellite overpasses and Dobson ozone datasets for NOASA/Goddard, Boulder, CO and MLO, HI sites are presented in this paper. The MSBU algorithm reduces noise in the intra-annual variability of the Brewer retrieved ozone as compared to the single pair ozone retrieval. Tropospheric ozone retrievals also

  19. Ozone is mutagenic in Salmonella

    SciTech Connect

    Dillon, D.; Combes, R.; McConville, M.; Zeiger, E. )

    1992-01-01

    Ozone is a highly reactive gas that has been tested for genotoxicity in a number of systems. Induced genetic damage resulting from ozone treatment may not be readily observed because of the high toxicity of the chemical and difficulties in generating and administering controlled concentrations. The mutagenicity of ozone was investigated in Salmonella typhimurium using a plate test protocol designed for reactive vapours and gases. Ozone, at two to three consecutive doses, induced weak, albeit statistically significant, mutagenic responses in tester strain TA102 with and without Aroclor-induced rat liver S9 (lowest effective mean concentration of 0.019 ppm; 35 min total exposure). However, dose-related responses were not always obtained. No mutagenicity was detected in strains TA98, TA100, or TA1535, with or without S9. In strain TA104, ozone induced a weak response only at a single dose with S9; this response was not reproducible. Mutagenicity was dependent on the ozone flow rate and total exposure time, with variations in the optimum dose-time regimen leading to toxicity or complete inactivity. The data show that ozone is a very weak bacterial mutagen and only when tested under narrowly prescribed, subtoxic dosing conditions.

  20. Total ozone trend over Cairo

    NASA Technical Reports Server (NTRS)

    Hassan, G. K. Y.

    1994-01-01

    A world wide interest in protecting ozone layer against manmade effects is now increasing. Assessment of the ozone depletion due to these activities depends on how successfully we can separate the natural variabilities from the data. The monthly mean values of total ozone over Cairo (30 05N) for the period 1968-1988, have been analyzed using the power spectral analysis technique. The technique used in this analysis does not depend on a pre-understanding of the natural fluctuations in the ozone data. The method depends on increasing the resolution of the spectral peaks in order to obtain the more accurate sinusoidal fluctuations with wavelength equal to or less than record length. Also it handles the possible sinusoidal fluctuations with wavelength equal to or less than record length. The results show that it is possible to detect some of the well known national fluctuations in the ozone record such as annual, semiannual, quasi-biennial and quasi-quadrennial oscillations. After separating the natural fluctuations from the ozone record, the trend analysis of total ozone over Cairo showed that a decrease of about -1.2% per decade has occurred since 1979.

  1. Synthesis of 2-arylamino substituted 5,6-dihydropyrido[2,3-d]pyrimidine-7(8H)-ones from arylguanidines.

    PubMed

    Galve, Iñaki; Puig de la Bellacasa, Raimon; Sánchez-García, David; Batllori, Xavier; Teixidó, Jordi; Borrell, José I

    2012-11-01

    A practical protocol was developed for the synthesis of 2-arylamino substituted 4-amino-5,6-dihydropyrido[2,3-d]pyrimidin-7(8H)-ones from α,β-unsaturated esters, malononitrile, and an aryl substituted guanidine via the corresponding 3-aryl-3,4,5,6- tetrahydropyrido[2,3-d]pyrimidin-7(8H)-ones. Such compounds are formed upon treatment of 2-methoxy-6-oxo-1,4,5,6-tetrahydropyridine-3-carbonitriles with an aryl substituted guanidine in 1,4-dioxane and are converted to the desired 4-aminopyridopyrimidines with NaOMe/MeOH through a Dimroth rearrangement. The overall yields of this three-step protocol are, generally speaking, higher than the multicomponent reaction, previously developed by our group, between an α,β-unsaturated ester, malononitrile, and an aryl substituted guanidine. PMID:23054532

  2. Decline and recovery of total column ozone using a multimodel time series analysis

    NASA Astrophysics Data System (ADS)

    Austin, John; Scinocca, J.; Plummer, D.; Oman, L.; Waugh, D.; Akiyoshi, H.; Bekki, S.; Braesicke, P.; Butchart, N.; Chipperfield, M.; Cugnet, D.; Dameris, M.; Dhomse, S.; Eyring, V.; Frith, S.; Garcia, R. R.; Garny, H.; Gettelman, A.; Hardiman, S. C.; Kinnison, D.; Lamarque, J. F.; Mancini, E.; Marchand, M.; Michou, M.; Morgenstern, O.; Nakamura, T.; Pawson, S.; Pitari, G.; Pyle, J.; Rozanov, E.; Shepherd, T. G.; Shibata, K.; TeyssèDre, H.; Wilson, R. J.; Yamashita, Y.

    2010-01-01

    Simulations of 15 coupled chemistry climate models, for the period 1960-2100, are presented. The models include a detailed stratosphere, as well as including a realistic representation of the tropospheric climate. The simulations assume a consistent set of changing greenhouse gas concentrations, as well as temporally varying chlorofluorocarbon concentrations in accordance with observations for the past and expectations for the future. The ozone results are analyzed using a nonparametric additive statistical model. Comparisons are made with observations for the recent past, and the recovery of ozone, indicated by a return to 1960 and 1980 values, is investigated as a function of latitude. Although chlorine amounts are simulated to return to 1980 values by about 2050, with only weak latitudinal variations, column ozone amounts recover at different rates due to the influence of greenhouse gas changes. In the tropics, simulated peak ozone amounts occur by about 2050 and thereafter total ozone column declines. Consequently, simulated ozone does not recover to values which existed prior to the early 1980s. The results also show a distinct hemispheric asymmetry, with recovery to 1980 values in the Northern Hemisphere extratropics ahead of the chlorine return by about 20 years. In the Southern Hemisphere midlatitudes, ozone is simulated to return to 1980 levels only 10 years ahead of chlorine. In the Antarctic, annually averaged ozone recovers at about the same rate as chlorine in high latitudes and hence does not return to 1960s values until the last decade of the simulations.

  3. What would have happened to the ozone layer if chlorofluorocarbons (CFCs) had not been regulated?

    NASA Astrophysics Data System (ADS)

    Oman, L.; Newman, P. A.; Douglass, A. R.; Fleming, E. L.; Frith, S. M.; Hurwitz, M.; Kawa, S. R.; Jackman, C. H.; Krotkov, N. A.; Nash, E. R.; Nielsen, J. E.; Pawson, S.; Stolarski, R. S.; Velders, G. J.

    2010-12-01

    The Montreal Protocol on Substances that Deplete the Ozone Layer was negotiated in 1987 and by 2010 had been signed by all of the nations of the world. In this presentation we use a fully coupled radiation-chemical-dynamical model to simulate a future world where ozone depletion substances (ODSs) were never regulated. In this “world avoided” simulation, ODS levels increase by 3% per year. From 1980 to 2020 we find that 17% of the globally average column ozone is destroyed, and from 1980 to 2065 67% is destroyed. Severe polar depletions (e.g., the Antarctic ozone hole) become year-round rather than just seasonal. Ozone levels in the tropical lower stratosphere remain constant until about 2053 and then collapse to near zero by 2058 as a result of heterogeneous chemical processes (as currently observed in the Antarctic ozone hole). The tropical cooling that triggers the ozone collapse is caused by an increase of the tropical lower stratospheric upwelling. In response to ozone changes, ultraviolet (UV) radiation increases, tripling the erythemal (sunburn) radiation in the northern summer mid-latitudes by 2065.

  4. Bactericidal activity, eggshell conductance, and hatchability effects of ozone versus formaldehyde disinfection

    SciTech Connect

    Whistler, P.E.; Sheldon, B.W. )

    1989-08-01

    Ozone and formaldehyde were evaluated as disinfectants in a prototype laboratory setter against microorganisms that are naturally present on fertile, freshly laid, broiler hatching eggs. Significantly lower microbial counts of over 2.5 log10 (P less than .05) were observed for water-misted and ozonated (2.83% by weight) eggs or formaldehyde-fumigated (triple strength) eggs than for control and water-misted eggs. Eggshell conductance studies as measured by egg moisture losses in a desiccator showed no significant differences (P greater than .05) among untreated, water misted, ozonated (3.06% by weight) with water mist, or formaldehyde (triple strength)-fumigated eggs. Hatchability was significantly reduced (26.5 to 37.5%) following ozonation (3.03% ozone by weight, 2 h) in comparison with effects of no treatment or water misting. Misting with ozonation was equally as effective as formaldehyde fumigation in reducing microbial counts. However, ozone treatment at the concentrations tested significantly reduced hatchability when compared with results of either no treatment, water misting, or an average hatchability figure for formaldehyde fumigation. These findings indicate that ozone is a good disinfectant yet may adversely affect embryo development when given in the gaseous form.

  5. Ozone profiles over McMurdo Station, Antarctica, during August, September, and October of 1986 - 1991

    NASA Technical Reports Server (NTRS)

    Deshler, Terry; Hofmann, David J.

    1994-01-01

    Vertical profiles of ozone and temperature have been measured at McMurdo Station, Antarctica, during the springs of 1986 to 1991, roughly every two days from 25 August to 31 October. Comparisons of temporal histories and average vertical structure for these years reveals some striking consistency in the ozone depletion process. Ozone depletion generally begins in early September, and with a half-life of 20-30 days, reaches its maximum in mid-October. The depletion occurs almost exclusively between 12 and 20 km. At the time of maximum depletion total ozone has been decreased roughly 40 percent while ozone between 12 and 20 km has been reduced 80 percent. Recovery generally begins in late October with the influx, above 20 km, of ozone rich air from the lower latitudes. From this record the worst years for ozone depletion were 1987, 1989, and 1990. A new region of ozone depletion, below 12 km, was observed in 1991, coinciding with the entrainment of a volcanic cloud into the polar vortex.

  6. Differences between recalculated and original Dobson total ozone data from Hradec Kralove, Czechoslovakia, 1962-1990

    NASA Technical Reports Server (NTRS)

    Vanicek, Karel

    1994-01-01

    Backward reevaluation of long-term total ozone measurements from the Solar and Ozone Observatory of Czech Hydrometeorological Institute at Hradec Kralove, Czechoslovakia, was performed for the period 1962-1990. The homogenization was carried out with respect to the calibration level of the World Primary Standard Spectrophotometer No. 83 - WPSS by means of day-by-day recalculations of more than 25,000 individual measurements using the R-N tables reconstructed after international comparisons and regular standard lamp tests of the Dobson spectrophotometer No. 74. The results showed significant differences among the recalculated data and those original ones published in the bulletins Ozone Data for the World. In the period 1962-1979 they reached 10-19 D.U. (3.0-5.5%) for annual averages and even 26 D.U. (7.0%) for monthly averages of total ozone. Such differences exceed several times accuracy of measuring and can significantly influence character of trends of total ozone in Central Europe. Therefore the results from Hradec Kralove support the calls for reevaluation of all historical Dobson total ozone data sets at individual stations of Global Ozone Observing System.

  7. Microphysical Modelling of the 1999-2000 Arctic Winter. 2; Chlorine Activation and Ozone Depletion

    NASA Technical Reports Server (NTRS)

    Drdla, K.; Schoeberl, M. R.; Gore, Warren J. (Technical Monitor)

    2001-01-01

    The effect of a range of assumptions about polar stratospheric clouds (PSCs) on ozone depletion has been assessed using at couple microphysical/photochemical model. The composition of the PSCs was varied (ternary solutions, nitric acid trihydrate, nitric acid dehydrate, or ice), as were parameters that affected the levels of denitrification and dehydration. Ozone depletion was affected by assumptions about PSC freezing because of the variability in resultant nitrification chlorine activation in all scenarios was similar despite the range of assumed PSC compositions. Vortex-average ozone loss exceeded 40% in the lower stratosphere for simulations without nitrification an additional ozone loss of 15-20% was possible in scenarios where vortex-average nitrification reached 60%. Ozone loss intensifies non-linearly with enhanced nitrification in air parcels with 90% nitrification 40% ozone loss in mid-April can be attributed to nitrification alone. However, these effects are sensitive to the stability of the vortex in springtime: nitrification only began to influence ozone depletion in mid-March.

  8. The impact of drought on ozone dry deposition over eastern Texas

    NASA Astrophysics Data System (ADS)

    Huang, Ling; McDonald-Buller, Elena C.; McGaughey, Gary; Kimura, Yosuke; Allen, David T.

    2016-02-01

    Dry deposition represents a critical pathway through which ground-level ozone is removed from the atmosphere. Understanding the effects of drought on ozone dry deposition is essential for air quality modeling and management in regions of the world with recurring droughts. This work applied the widely used Zhang dry deposition algorithm to examine seasonal and interannual changes in estimated ozone dry deposition velocities and component resistances/conductances over eastern Texas during years with drought (2006 and 2011) as well as a year with slightly cooler temperatures and above average rainfall (2007). Simulated area-averaged daytime ozone dry deposition velocities ranged between 0.26 and 0.47 cm/s. Seasonal patterns reflected the combined seasonal variations in non-stomatal and stomatal deposition pathways. Daytime ozone dry deposition velocities during the growing season were consistently larger during 2007 compared to 2006 and 2011. These differences were associated with differences in stomatal conductances and were most pronounced in forested areas. Reductions in stomatal conductances under drought conditions were highly sensitive to increases in vapor pressure deficit and warmer temperatures in Zhang's algorithm. Reductions in daytime ozone deposition velocities and deposition mass during drought years were associated with estimates of higher surface ozone concentrations.

  9. Ultrafine particles generated from coloring with scented markers in the presence of ozone.

    PubMed

    Fung, C-C D; Shu, S; Zhu, Y

    2014-10-01

    High concentrations of ultrafine particles (UFPs) have been previously reported during school art activities. This is possibly due to secondary organic aerosols (SOAs) formed from reactions between ozone and volatile organic compounds emitted from art products. Four brands of markers, three scented and one unscented, were tested inside a stainless steel chamber at eight different ozone concentrations between 0 and 300 ppb. Out of the 32 tested markers, only the lemon- and orange-scented markers from one brand reacted with ozone to form UFPs. Limonene, pinene, and several other terpenes were identified as ingredients of ink in SOA-forming markers. Coloring with one lemon-scented marker for 1 min without ozone generated on average approximately 26 ± 4 ppb of limonene inside the chamber. At 150 ppb ozone, using one lemon marker for 1 min formed on average 7.7 × 10(10) particles. The particle size distribution indicated an initial mode of 15 nm which grew to 40 nm. At 50 ppb ozone and below, no significant SOA formation occurred. The number of particles formed is moderately correlated with the mass of ink used (R(2)  = 0.68). Based on these data, scented markers are not likely a strong source of SOA under normal indoor ozone levels. PMID:24547888

  10. The impact of meteorology on ozone in Houston

    SciTech Connect

    Eder, B.K.; Davis, J.M.; Nychka, D.

    1997-12-31

    This paper compares the results from both a one-stage hierarchical clustering technique (average linkage) and a two-stage technique (average linkage then k-means) as part of an objective meteorological Classification scheme designed to better elucidate ozone`s dependence on meteorology in the Houston, Texas, area. When applied to twelve years of meteorological data (1981-1992), each technique identified seven statistically distinct meteorological regimes, the majority of which exhibited significantly different daily 1-hour maximum ozone (O{sub 3}) concentrations. While both clustering approaches proved successful, the two-stage approach did appear superior in terms of better segregation of the mean O{sub 3}, concentrations. Both approaches indicated that the largest mean daily one-hour maximum concentrations are associated with migrating anticyclones and not with the quasi-permanent Bermuda High that often dominates the southeastern United States during the summer. As a result, maximum ozone concentrations are just as likely during the months of April, May, September and October as they are during the summer months. These findings support and help explain the unique O{sub 3}, climatology experienced by the Houston area.

  11. Comparison of the diagnostic yield and outcomes between standard 8 h capsule endoscopy and the new 12 h capsule endoscopy for investigating small bowel pathology

    PubMed Central

    Rahman, Merajur; Akerman, Stuart; DeVito, Bethany; Miller, Larry; Akerman, Meredith; Sultan, Keith

    2015-01-01

    AIM: To evaluate the completion rate and diagnostic yield of the PillCam SB2-ex in comparison to the PillCam SB2. METHODS: Two hundred cases using the 8-h PillCam SB2 were retrospectively compared to 200 cases using the 12 h PillCam SB2-ex at a tertiary academic center. Endoscopically placed capsules were excluded from the study. Demographic information, indications for capsule endoscopy, capsule type, study length, completion of exam, clinically significant findings, timestamp of most distant finding, and significant findings beyond 8 h were recorded. RESULTS: The 8 and 12 h capsule groups were well matched respectively for both age (70.90 ± 14.19 vs 71.93 ± 13.80, P = 0.46) and gender (45.5% vs 48% male, P = 0.69). The most common indications for the procedure in both groups were anemia and obscure gastrointestinal bleeding. PillCam SB2-ex had a significantly higher completion rate than PillCam SB2 (88% vs 79.5%, P = 0.03). Overall, the diagnostic yield was greater for the 8 h capsule (48.5% for SB2 vs 35% for SB2-ex, P = 0.01). In 4/70 (5.7%) of abnormal SB2-ex exams the clinically significant finding was noted in the small bowel beyond the 8 h mark. CONCLUSION: In our study, we found the PillCam SB2-ex to have a significantly increased completion rate, though without any improvement in diagnostic yield compared to the PillCam SB2. PMID:25987777

  12. High average power pockels cell

    DOEpatents

    Daly, Thomas P.

    1991-01-01

    A high average power pockels cell is disclosed which reduces the effect of thermally induced strains in high average power laser technology. The pockels cell includes an elongated, substantially rectangular crystalline structure formed from a KDP-type material to eliminate shear strains. The X- and Y-axes are oriented substantially perpendicular to the edges of the crystal cross-section and to the C-axis direction of propagation to eliminate shear strains.

  13. The National Ozone Expedition, 1986

    SciTech Connect

    Solomon, S. )

    1987-01-01

    Eighteen scientists from four separate institutions came to McMurdo Station during the period from August to November, 1986, to carry out an intensive stratospheric measurement program aimed at obtaining further data on the antarctic ozone hole. The results from the composite of experiments strongly suggest that chemistry (specifically, the chemistry of anthropogenically produced halocarbon species) probably plays an important role in the development of the antarctic ozone hole. If the antarctic ozone hole is due to mankind's use of chlorofluorocarbons, then it represents the first time that the environment has been shown to be sensitive to man's activities on a global scale.

  14. Ozone and ozonated oils in skin diseases: a review.

    PubMed

    Travagli, V; Zanardi, I; Valacchi, G; Bocci, V

    2010-01-01

    Although orthodox medicine has provided a variety of topical anti-infective agents, some of them have become scarcely effective owing to antibiotic- and chemotherapeutic-resistant pathogens. For more than a century, ozone has been known to be an excellent disinfectant that nevertheless had to be used with caution for its oxidizing properties. Only during the last decade it has been learned how to tame its great reactivity by precisely dosing its concentration and permanently incorporating the gas into triglycerides where gaseous ozone chemically reacts with unsaturated substrates leading to therapeutically active ozonated derivatives. Today the stability and efficacy of the ozonated oils have been already demonstrated, but owing to a plethora of commercial products, the present paper aims to analyze these derivatives suggesting the strategy to obtain products with the best characteristics. PMID:20671923

  15. Ozone and Ozonated Oils in Skin Diseases: A Review

    PubMed Central

    Travagli, V.; Zanardi, I.; Valacchi, G.; Bocci, V.

    2010-01-01

    Although orthodox medicine has provided a variety of topical anti-infective agents, some of them have become scarcely effective owing to antibiotic- and chemotherapeutic-resistant pathogens. For more than a century, ozone has been known to be an excellent disinfectant that nevertheless had to be used with caution for its oxidizing properties. Only during the last decade it has been learned how to tame its great reactivity by precisely dosing its concentration and permanently incorporating the gas into triglycerides where gaseous ozone chemically reacts with unsaturated substrates leading to therapeutically active ozonated derivatives. Today the stability and efficacy of the ozonated oils have been already demonstrated, but owing to a plethora of commercial products, the present paper aims to analyze these derivatives suggesting the strategy to obtain products with the best characteristics. PMID:20671923

  16. Dobson spectrophotometer ozone measurements during international ozone rocketsonde intercomparison

    NASA Technical Reports Server (NTRS)

    Parsons, C. L.

    1980-01-01

    Measurements of the total ozone content of the atmosphere, made with seven ground based instruments at a site near Wallops Island, Virginia, are discussed in terms for serving as control values with which the rocketborne sensor data products can be compared. These products are profiles of O3 concentration with altitude. By integrating over the range of altitudes from the surface to the rocket apogee and by appropriately estimating the residual ozone amount from apogee to the top of the atmosphere, a total ozone amount can be computed from the profiles that can be directly compared with the ground based instrumentation results. Dobson spectrophotometers were used for two of the ground-based instruments. Preliminary data collected during the IORI from Dobson spectrophotometers 72 and 38 are presented. The agreement between the two and the variability of total ozone overburden through the experiment period are discussed.

  17. Sensitivity Studies for Assimilated Ozone Profiles

    NASA Technical Reports Server (NTRS)

    Stajner, Ivanka; Winslow, Nathan; Wargan, Krzysztof; Rood, Richard; Pawson, Steven

    2002-01-01

    An ozone data assimilation system at the NASA/Goddard Data Assimilation Office (DAO) produces three-dimensional global ozone fields. They are obtained by assimilating ozone retrieved from the Solar Backscatter UltraViolet/2 (SBUV/2) instrument and the Earth Probe Total Ozone Mapping Spectrometer (EP TOMS) measurements into an off-line parameterized chemistry and transport model. In this talk we focus on the quality of lower stratospheric assimilated ozone profiles. Ozone in the lower stratosphere plays a key role in the forcing of climate. A biased ozone field in this region will adversely impact calculations of the stratosphere-troposphere exchange and, when used as a first guess in retrievals, the values determined from satellite observations. The SBUV/2 ozone data have a coarse vertical resolution with increased uncertainty below the ozone maximum, and TOMS provides only total ozone columns. Thus, the assimilated ozone profiles in the lower stratosphere are only weakly constrained by the incoming SBUV and TOMS data. Consequently, the assimilated ozone distribution should be sensitive to changes in inputs to the statistical analysis scheme. We investigate the sensitivity of assimilated ozone profiles to changes in a variety of system inputs: TOMS and SBUV/2 data selection, forecast and observations error covariance models, inclusion or omission of a parameterized chemistry model, and different versions of DAO assimilated wind fields used to drive the transport model. Comparisons of assimilated ozone fields with independent observations, primarily ozone sondes, are used to determine the impact of each of these changes.

  18. The sensitivity of global ozone predictions to dry deposition schemes and their response to climate change

    NASA Astrophysics Data System (ADS)

    Centoni, Federico; Stevenson, David; Fowler, David; Nemitz, Eiko; Coyle, Mhairi

    2015-04-01

    Concentrations of ozone at the surface are strongly affected by deposition to the surface. Deposition processes are very sensitive to temperature and relative humidity at the surface and are expected to respond to global change, with implications for both air quality and ecosystem services. Many studies have shown that ozone stomatal uptake by vegetation typically accounts for 40-60% of total deposition on average and the other part which occurs through non-stomatal pathways is not constant. Flux measurements show that non-stomatal removal increases with temperature and under wet conditions. There are large uncertainties in parameterising the non-stomatal ozone deposition term in climate chemistry models and model predictions vary greatly. In addition, different model treatments of dry deposition constitute a source of inter-model variability in surface ozone predictions. The main features of the original Unified Model-UK Chemistry and Aerosols (UM-UKCA) dry deposition scheme and the Zhang et al. 2003 scheme, which introduces in UM-UKCA a more developed non-stomatal deposition approach, are presented. This study also estimates the relative contributions of ozone flux via stomatal and non-stomatal uptakes at the global scale, and explores the sensitivity of simulated surface ozone and ozone deposition flux by implementing different non-stomatal parameterization terms. With a view to exploring the potential influence of future climate, we present results showing the effects of variations in some meteorological parameters on present day (2000) global ozone predictions. In particular, this study revealed that the implementation of a more mechanistic representation of the non-stomatal deposition in UM-UKCA model along with a decreased stomatal uptake due to the effect of blocking under wet conditions, accounted for a substantial reduction of ozone fluxes to broadleaf trees in the tropics with an increase of annual mean surface ozone. On the contrary, a large increase of

  19. Ozone depuration of Vibrio vulnificus from the southern quahog clam, Mercenaria campechiensis

    SciTech Connect

    Schneider, K.R.; Steslow, F.S.; Sierra, F.S.; Rodrick, G.E.; Noss, C.I. )

    1991-03-01

    Southern quahog clams, Mercenaria campechiensis, were dosed with Vibrio vulnificus and placed in a pilot-scale depuration system using ozonated recirculated artificial seawater. Twenty-four hours of treatment with ozone-treated recirculating artificial seawater reduced the numbers of V. vulnificus in the shellfish meats by an average of 2 log units when compared to natural die-off in control clams. The oxidant levels (up to 3 mg/liter) did not adversely affect shellfish pumping during the depuration process.

  20. Effects of Volcanic Eruptions on Stratospheric Ozone Recovery

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.

    2002-01-01

    The effects of the stratospheric sulfate aerosol layer associated with the Mt. Pinatubo volcano and future volcanic eruptions on the recovery of the ozone layer is studied with an interactive two-dimensional photochemical model. The time varying chlorine loading and the stratospheric cooling due to increasing carbon dioxide have been taken into account. The computed ozone and temperature changes associated with the Mt. Pinatubo eruption in 1991 agree well with observations. Long model runs out to the year 2050 have been carried out, in which volcanoes having the characteristics of the Mount Pinatubo volcano were erupted in the model at 10-year intervals starting in the year 2010. Compared to a non-volcanic run using background aerosol loading, transient reductions of globally averaged column ozone of 2-3 percent were computed as a result of each of these eruptions, with the ozone recovering to that computed for the non-volcanic case in about 5 years after the eruption. Computed springtime Arctic column ozone losses of from 10 to 18 percent also recovered to the non-volcanic case within 5 years. These results suggest that the long-term recovery of ozone would not be strongly affected by infrequent volcanic eruptions with a sulfur loading approximating Mt. Pinatubo. Sensitivity studies in which the Arctic lower stratosphere was forced to be 4 K and 10 K colder resulted in transient ozone losses of which also recovered to the non-volcanic case in 5 years. A case in which a volcano five times Mt. Pinatubo was erupted in the year 2010 led to maximum springtime column ozone losses of 45 percent which took 10 years to recover to the background case. Finally, in order to simulate a situation in which frequent smaller volcanic eruptions result in increasing the background sulfate loading, a simulation was made in which the background aerosol was increased by 10 percent per year. This resulted in a delay of the recovery of column ozone to 1980 values of more than 10 years.

  1. Advanced oxidation processes for wastewater treatment using a plasma/ozone combination system

    NASA Astrophysics Data System (ADS)

    Takeuchi, Nozomi; Kamiya, Yu; Saeki, Ryo; Tachibana, Kosuke; Yasuoka, Koichi

    2014-10-01

    Advanced oxidation process (AOP) using OH radicals is a promising method for the decomposition of persistent organic compounds in wastewater. Although many types of plasma reactors have been developed for the AOP, they are unsuitable for the complete decomposition of highly concentrated organic compounds. The reason for the incomplete decomposition is that OH radicals, particularly at a high density, recombine among themselves to form hydrogen peroxide. We have developed a combination plasma reactor in which ozone gas is fed, so that the generated hydrogen peroxide is re-converted to OH radicals. Pulsed plasmas generated within oxygen bubbles supply not only OH radicals but also hydrogen peroxide into wastewater. The total organic carbon (TOC) of the wastewater was more than 1 gTOC/L. The TOC values decreased linearly with time, and the persistent compounds which could not be decomposed by ozone were completely mineralized within 8 h of operation.

  2. Ozone Monitoring Instrument

    NASA Astrophysics Data System (ADS)

    de Vries, Johan

    The Ozone Monitoring Instrument is a trace gas monitoring instrument in the line of GOME (ERS-2) and Sciamachy (ENVISAT). Following these instruments, OMI provides UV-visible spectroscopy with a resolution sufficient to separate out the various absorbing trace gases (using DOAS or `Full' retrieval), but shaped as an imaging spectrometer. This means that a two dimensional detector is used where one dimension records the spectrum and the other images the swath. The scanning mechanism from the GOME and Sciamachy is not required anymore and there are considerable advantages with respect to simultaneous measurement of swath pixels, polarisation and obtainable swath width. The OMI consortium for a phase B is formed by Fokker Space & Systems and TPD in the Netherlands and VTT in Finland. In the presentation UV-visible atmospheric remote sensing will be placed in perspective and the OMI will be explaned.

  3. The photolysis of ozone

    NASA Technical Reports Server (NTRS)

    Lissi, E.; Heicklen, J.

    1972-01-01

    Ozone was photolyzed at 25 C with steady illumination at several wavelengths from 2288 to 2850 A, at O3 pressures from 0.1 to 2.7 torr, and at absorbed intensities from 0.15 to 65 microns/min. Experiments were done in pure dry O3, and in the presence of He, CO2, N2, H2O, H2, N2O, He-CO2, He-H2O, CO2-H2O, O2-N2O, CO2-O2, and N2O5-O2-CO2 mixtures. The results show that in the absence of added gases or in the presence of He, the quantum yield of O3 consumption is 5.5 independent of conditions, except at pressures below 0.4 torr. In the presence of CO2 or N2, ozone consumption falls toward 4.0. The primary photolytic act produces O(1 D) and siglet O2, presumably O2(1 delta), at all wavelengths below 3000 A. Relative quenching constants O(1 D) removal by various gases were measured at 2288, 2537, and 2800 A. For O3, CO2, and N2, the relative rates are 1.0/0.4 to 0.5/0.08 to 0.11 at all wavelengths. For H2O the constant at 2537 A is 1.5 relative to that for O3. With N2O, a noticeable wavelength effect is observed and the relative rate constants are 1.5, 2 to 3, 4.0 for O3 compared to N2O at 2800, 2537, and 2288 A, respectively.

  4. Ozonation of cooling tower waters

    NASA Technical Reports Server (NTRS)

    Humphrey, M. F.; French, K. R.; Howe, R. D. (Inventor)

    1979-01-01

    Continuous ozone injection into water circulating between a cooling tower and heat exchanger with heavy scale deposits inhibits formation of further deposits, promotes flaking of existing deposits, inhibits chemical corrosion and controls algae and bacteria.

  5. Air Quality Guide for Ozone

    MedlinePlus

    ... is one of our nation’s most common air pollutants. Use the chart below to help reduce your ... human health. Ozone forms when two types of pollutants (VOCs and NOx) react in sunlight. These pollutants ...

  6. A search For Artic ozone

    NASA Astrophysics Data System (ADS)

    Maggs, William Ward

    Four atmospheric scientists took off with their instruments for Greenland last week, where they will try to see if depletion of stratospheric ozone in the Arctic can be detected as it has been in Antarctica since 1985.Members of the scientific team include Susan Solomon and George Mount of the Aeronomy Laboratory at the National Atmospheric and Oceanic Administration (NOAA) in Boulder, Colo., and Ryan Sanders and Roger Jakoubec of the Cooperative Institute for Research in Environmental Science in Norman, Okla. These four participated in previous National Ozone Expedition (NOZE) investigations at McMurdo Station in Antarctica that helped document the ozone “hole,” decreases of up to 50% in ozone during the early austral spring in September and October of the last 2 years (1986-1987).

  7. Ozone - Current Air Quality Index

    MedlinePlus

    ... reducing exposure to extremely high levels of particle pollution is available here . Fires: Current Conditions Click to ... Air Quality Basics Air Quality Index | Ozone | Particle Pollution | Smoke from fires | What You Can Do Health ...

  8. Vocal attractiveness increases by averaging.

    PubMed

    Bruckert, Laetitia; Bestelmeyer, Patricia; Latinus, Marianne; Rouger, Julien; Charest, Ian; Rousselet, Guillaume A; Kawahara, Hideki; Belin, Pascal

    2010-01-26

    Vocal attractiveness has a profound influence on listeners-a bias known as the "what sounds beautiful is good" vocal attractiveness stereotype [1]-with tangible impact on a voice owner's success at mating, job applications, and/or elections. The prevailing view holds that attractive voices are those that signal desirable attributes in a potential mate [2-4]-e.g., lower pitch in male voices. However, this account does not explain our preferences in more general social contexts in which voices of both genders are evaluated. Here we show that averaging voices via auditory morphing [5] results in more attractive voices, irrespective of the speaker's or listener's gender. Moreover, we show that this phenomenon is largely explained by two independent by-products of averaging: a smoother voice texture (reduced aperiodicities) and a greater similarity in pitch and timbre with the average of all voices (reduced "distance to mean"). These results provide the first evidence for a phenomenon of vocal attractiveness increases by averaging, analogous to a well-established effect of facial averaging [6, 7]. They highlight prototype-based coding [8] as a central feature of voice perception, emphasizing the similarity in the mechanisms of face and voice perception. PMID:20129047

  9. Determining GPS average performance metrics

    NASA Technical Reports Server (NTRS)

    Moore, G. V.

    1995-01-01

    Analytic and semi-analytic methods are used to show that users of the GPS constellation can expect performance variations based on their location. Specifically, performance is shown to be a function of both altitude and latitude. These results stem from the fact that the GPS constellation is itself non-uniform. For example, GPS satellites are over four times as likely to be directly over Tierra del Fuego than over Hawaii or Singapore. Inevitable performance variations due to user location occur for ground, sea, air and space GPS users. These performance variations can be studied in an average relative sense. A semi-analytic tool which symmetrically allocates GPS satellite latitude belt dwell times among longitude points is used to compute average performance metrics. These metrics include average number of GPS vehicles visible, relative average accuracies in the radial, intrack and crosstrack (or radial, north/south, east/west) directions, and relative average PDOP or GDOP. The tool can be quickly changed to incorporate various user antenna obscuration models and various GPS constellation designs. Among other applications, tool results can be used in studies to: predict locations and geometries of best/worst case performance, design GPS constellations, determine optimal user antenna location and understand performance trends among various users.

  10. Unraveling the sources of ground level ozone in the Intermountain Western United States using Pb isotopes.

    PubMed

    Christensen, John N; Weiss-Penzias, Peter; Fine, Rebekka; McDade, Charles E; Trzepla, Krystyna; Brown, Shaun T; Gustin, Mae Sexauer

    2015-10-15

    Ozone as an atmospheric pollutant is largely produced by anthropogenic precursors and can significantly impact human and ecosystem health, and climate. The U.S. Environmental Protection Agency has recently proposed lowering the ozone standard from 75 ppbv (MDA8 = Maximum Daily 8-Hour Average) to between 65 and 70 ppbv. This will result in remote areas of the Intermountain West that includes many U.S. National Parks being out of compliance, despite a lack of significant local sources. We used Pb isotope fingerprinting and back-trajectory analysis to distinguish sources of imported ozone to Great Basin National Park in eastern Nevada. During discrete Chinese Pb events (> 1.1 ng/m(3) & > 80% Asian Pb) trans-Pacific transported ozone was 5 ± 5.5 ppbv above 19 year averages for those dates. In contrast, concentrations during regional transport from the Los Angeles and Las Vegas areas were 15 ± 2 ppbv above the long-term averages, and those characterized by high-altitude transport 3 days prior to sampling were 19 ± 4ppbv above. However, over the study period the contribution of trans-Pacific transported ozone increased at a rate of 0.8 ± 0.3 ppbv/year, suggesting that Asian inputs will exceed regional and high altitude sources by 2015-2020. All of these sources will impact regulatory compliance with a new ozone standard, given increasing global background. PMID:25934382

  11. A Multi-sensor Upper Tropospheric Ozone Product (MUTOP) based on TES ozone and GOES water vapor: validation with ozonesondes

    NASA Astrophysics Data System (ADS)

    Moody, J. L.; Felker, S. R.; Wimmers, A. J.; Osterman, G.; Bowman, K.; Thompson, A. M.; Tarasick, D. W.

    2011-11-01

    Accurate representation of ozone in the extratropical upper troposphere (UT) remains a challenge. However, the implementation of hyper-spectral remote sensing using satellite instruments such as the Tropospheric Emission Spectrometer (TES) provides an avenue for mapping ozone in this region, from 500 to 300 hPa. As a polar orbiting satellite TES observations are limited, but in this paper they are combined with geostationary satellite observations of water vapor. This paper describes a validation of the Multi-sensor UT Ozone Product (MUTOP). MUTOP is statistical retrieval method, a derived product image based on the correlation of two remotely sensed quantities, TES ozone, against geostationary (GOES) specific humidity and modeled potential vorticity, a dynamical tracer in the UT. These TES-derived UT ozone mixing ratios are compared to coincident ozonesonde measurements of layer-average UT ozone mixing ratios made during the NASA INTEX/B field campaign in the spring of 2006; the region for this study is effectively the GOES west domain covering the Eastern North Pacific Ocean and the Western United States. This intercomparison evaluates MUTOP skill at representing ozone magnitude and variability in this region of complex dynamics. In total, 11 ozonesonde launch sites were available for this study, providing 127 individual sondes for comparison; the overall mean ozone of the 500-300 hPa layer for these sondes was 78.0 ppbv. MUTOP reproduces in-situ measurements reasonably well, producing an UT mean of 82.3 ppbv, with a mean absolute error of 12.2 ppbv and a root mean square error of 16.4 ppbv relative to ozonesondes across all sites. An overall UT mean bias of 4.3 ppbv relative to sondes was determined for MUTOP. Considered in the context of past TES validation studies, these results illustrate that MUTOP is able to maintain accuracy similar to TES while expanding coverage to the entire GOES-West satellite domain. In addition MUTOP provides six-hour temporal

  12. A multi-sensor upper tropospheric ozone product (MUTOP) based on TES ozone and GOES water vapor: validation with ozonesondes

    NASA Astrophysics Data System (ADS)

    Moody, J. L.; Felker, S. R.; Wimmers, A. J.; Osterman, G.; Bowman, K.; Thompson, A. M.; Tarasick, D. W.

    2012-06-01

    Accurate representation of ozone in the extratropical upper troposphere (UT) remains a challenge. However, the implementation of hyper-spectral remote sensing using satellite instruments such as the Tropospheric Emission Spectrometer (TES) provides an avenue for mapping ozone in this region, from 500 to 300 hPa. As a polar orbiting satellite TES observations are limited, but in this paper they are combined with geostationary satellite observations of water vapor. This paper describes a validation of the Multi-sensor UT Ozone Product (MUTOP). MUTOP, based on a statistical retrieval method, is an image product derived from the multiple regression of remotely sensed TES ozone, against geostationary (GOES) specific humidity (remotely sensed) and potential vorticity (a modeled dynamical tracer in the UT). These TES-derived UT ozone mixing ratios are compared to coincident ozonesonde measurements of layer-average UT ozone mixing ratios made during the NASA INTEX/B field campaign in the spring of 2006; the region for this study is effectively the GOES west domain covering the eastern North Pacific Ocean and the western United States. This intercomparison evaluates MUTOP skill at representing ozone magnitude and variability in this region of complex dynamics. In total, 11 ozonesonde launch sites were available for this study, providing 127 individual sondes for comparison; the overall mean ozone of the 500-300 hPa layer for these sondes was 78.0 ppbv. MUTOP reproduces in~situ measurements reasonably well, producing an UT mean of 82.3 ppbv, with a mean absolute error of 12.2 ppbv and a root mean square error of 16.4 ppbv relative to ozonesondes across all sites. An overall UT mean bias of 4.3 ppbv relative to sondes was determined for MUTOP. Considered in the context of past TES validation studies, these results illustrate that MUTOP is able to maintain accuracy similar to TES while expanding coverage to the entire GOES-West satellite domain. In addition MUTOP provides six

  13. Ozone Monitoring Instrument geolocation verification

    NASA Astrophysics Data System (ADS)

    Kroon, M.; Dobber, M. R.; Dirksen, R.; Veefkind, J. P.; van den Oord, G. H. J.; Levelt, P. F.

    2008-08-01

    Verification of the geolocation assigned to individual ground pixels as measured by the Ozone Monitoring Instrument (OMI) aboard the NASA EOS-Aura satellite was performed by comparing geophysical Earth surface details as observed in OMI false color images with the high-resolution continental outline vector map as provided by the Interactive Data Language (IDL) software tool from ITT Visual Information Solutions. The OMI false color images are generated from the OMI visible channel by integration over 20-nm-wide spectral bands of the Earth radiance intensity around 484 nm, 420 nm, and 360 nm wavelength per ground pixel. Proportional to the integrated intensity, we assign color values composed of CRT standard red, green, and blue to the OMI ground pixels. Earth surface details studied are mostly high-contrast coast lines where arid land or desert meets deep blue ocean. The IDL high-resolution vector map is based on the 1993 CIA World Database II Map with a 1-km accuracy. Our results indicate that the average OMI geolocation offset over the years 2005-2006 is 0.79 km in latitude and 0.29 km in longitude, with a standard deviation of 1.64 km in latitude and 2.04 km in longitude, respectively. Relative to the OMI nadir pixel size, one obtains mean displacements of ˜6.1% in latitude and ˜1.2% in longitude, with standard deviations of 12.6% and 7.9%, respectively. We conclude that the geolocation assigned to individual OMI ground pixels is sufficiently accurate to support scientific studies of atmospheric features as observed in OMI level 2 satellite data products, such as air quality issues on urban scales or volcanic eruptions and its plumes, that occur on spatial scales comparable to or smaller than OMI nadir pixels.

  14. Impact of synoptic controls and boundary layer processes on ground-level ozone evolution at an urban site

    NASA Astrophysics Data System (ADS)

    Haman, Christine Lanier

    Houston, Texas frequently exceeds the standard for ground-level ozone during the spring and fall. The large commuting population and vast number of industrial sources provide the necessary ingredients for photochemical ozone production in the presence of favorable meteorological conditions. The lack of continuous boundary layer (BL) observations prevents a comprehensive understanding of its role in ozone evolution. In this study, almost two years of BL observations are utilized to investigate the impacts of synoptic and micrometeorological-scale forcings on ozone. Aerosol gradients derived from ceilometer backscatter retrievals are used to identify the BL and residual layers (RL). Overall agreement is found between ceilometer and sonde estimates of the RL and BL heights (BLH), but difficulty detecting the layers occurs during cloud periods or immediately following precipitation. Large monthly variability is present in the peak afternoon BLH (e.g. mean August and December peaks are ˜2000 and 1100 m, respectively). Monthly nocturnal BLHs display much smaller differences. The majority of ozone exceedances occur during large-scale subsidence and weak winds in a postfrontal environment. These conditions result in turbulent kinetic energy, mechanical mixing, and ventilation processes that are 2--3 times weaker on exceedance days, which inhibit morning BL growth by an average of ˜100 m·hr-1 compared to low ozone days. The spring has higher nocturnal ozone levels, which is likely attributable to longer day lengths (˜78 minutes), stronger winds (˜0.78 m·s -1), and higher background ozone (˜5 ppbv) compared to the fall. Boundary layer entrainment plays an important role in ozone evolution. Exceedance days show a characteristic early morning rapid rise of ozone. Vertical ozone profiles indicate the RL ozone peak is ˜60 ppbv on exceedance days, which is ˜25 ppbv (+/- 10 ppbv) greater than low ozone days. The Integrated Profile Mixing (IPM) and Photochemical Budget (PB

  15. Method of sterilization using ozone

    NASA Technical Reports Server (NTRS)

    Murphy, Oliver J. (Inventor); Hitchens, G. Duncan (Inventor)

    2002-01-01

    Methods of using ozone have been developed which sterilize instruments and medical wastes, oxidize, organics found in wastewater, clean laundry, break down contaminants in soil into a form more readily digested by microbes, kill microorganisms present in food products, and destroy toxins present in food products. The preferred methods for killing microorganism and destroying toxins use pressurized, humidified, and concentrated ozone produced by an electrochemical cell.

  16. Ozone Treatment For Cooling Towers

    NASA Technical Reports Server (NTRS)

    Blackwelder, Rick; Baldwin, Leroy V.; Feeney, Ellen S.

    1990-01-01

    Report presents results of study of cooling tower in which water treated with ozone instead of usual chemical agents. Bacteria and scale reduced without pollution and at low cost. Operating and maintenance costs with treatment about 30 percent of those of treatment by other chemicals. Corrosion rates no greater than with other chemicals. Advantage of ozone, even though poisonous, quickly detected by smell in very low concentrations.

  17. Evaluations of average level spacings

    SciTech Connect

    Liou, H.I.

    1980-01-01

    The average level spacing for highly excited nuclei is a key parameter in cross section formulas based on statistical nuclear models, and also plays an important role in determining many physics quantities. Various methods to evaluate average level spacings are reviewed. Because of the finite experimental resolution, to detect a complete sequence of levels without mixing other parities is extremely difficult, if not totally impossible. Most methods derive the average level spacings by applying a fit, with different degrees of generality, to the truncated Porter-Thomas distribution for reduced neutron widths. A method that tests both distributions of level widths and positions is discussed extensivey with an example of /sup 168/Er data. 19 figures, 2 tables.

  18. Using ozone to treat cooling tower water

    SciTech Connect

    Webster, L.

    1995-07-01

    Ozone is a controversial but promising alternative to chemicals for treating water in cooling towers. A powerful disinfectant, ozone can prevent biofouling of heat exchange surfaces, and may mitigate scale and corrosion. Ozone treatment of cooling towers can cut costs for energy, water, sewage, and regulatory compliance. Ozone treatment is an electrotechnology, but ozone equipment represents only a small electric load. Although ozone has provided excellent results in some cooling tower applications, its effectiveness has not been proven conclusively. Less than 1,000 cooling towers use ozone water treatment in the United States. Acceptance of this technology is increasing, however, as indicated by its use by such large firms as IBM, AT and T, DuPont, and Xerox, and by its adoption by some chemical water treatment suppliers. The energy efficiency implications of ozone treatment are being researched. Southern California Edison found that in some systems, ozone treatment improved chiller efficiency up to 20 percent due to cleaner heat exchange surfaces.

  19. Corona Discharge Influences Ozone Concentrations Near Rats

    SciTech Connect

    Goheen, Steven C.; Gaither, Kari A.; Anantatmula, Shantha M.; Mong, Gary M.; Sasser, Lyle B.; Lessor, Delbert L.

    2004-02-26

    Ozone is produced by corona discharge in air. Its production is enhanced near grounded water. Whether grounded animals behave like grounded water, producing more ozone was investigated. Rats were exposed to corona discharge in a plastic cage. The concentration of ozone in the gas phase was monitored. The ozone concentration exceeded ambient levels only in the presence of corona discharge and either rats or water. When water or rats were exposed to corona discharge, ozone levels were more than 10 times higher than controls. Ozone levels increased rapidly with applied voltage. There was also a correlation between the distance of the corona needle to the rats and the amount of ozone produced. As the distance increased, ozone production decreased. These results are discussed in relation to the potential exposure of mammals to ozone in the vicinity of corona discharge and electric fields.

  20. Ground-level ozone in Alberta

    SciTech Connect

    Sandhu, H.S.

    1999-11-01

    This literature review on ground-level ozone in Alberta begins with introductory sections on the precursors and products of ozone formation, the chemistry and meteorology of ozone, and atmospheric ozone models. The subsequent section reviews ozone data from ambient air quality monitoring stations in Alberta. The final section discusses trends in ozone concentrations in urban and rural areas of Alberta, human and environmental health effects of ozone, proposed national ambient objectives and Canada-wide standards for ground-level ozone, and options for an ozone concentration standard for Alberta. Appendices include an outline of air pollutant monitoring methods used in Alberta, lists of monitoring stations, and tables of monitoring results for nitrogen oxides, total hydrocarbons, and volatile organic compounds at Calgary and Edmonton sites.

  1. Ground-level ozone in Alberta

    SciTech Connect

    Sandhu, H.S.

    1999-01-01

    This literature review on ground-level ozone in Alberta begins with introductory sections on the precursors and products of ozone formation, the chemistry and meteorology of ozone, and atmospheric ozone models. The subsequent section reviews ozone data from ambient air quality monitoring stations in Alberta. The final section discusses trends in ozone concentrations in urban and rural areas of Alberta, human and environmental health effects of ozone, proposed national ambient objectives and Canada-wide standards for ground-level ozone, and options for an ozone concentration standard for Alberta. Appendices include an outline of air pollutant monitoring methods used in Alberta, lists of monitoring stations, and tables of monitoring results for nitrogen oxides, total hydrocarbons, and volatile organic compounds at Calgary and Edmonton sites.

  2. Effect of C-fiber-mediated, ozone-induced rapid shallow breathing on airway epithelial injury in rats.

    PubMed

    Schelegle, E S; Alfaro, M F; Putney, L; Stovall, M; Tyler, N; Hyde, D M

    2001-10-01

    We examined the relationship between C-fiber-mediated, ozone-induced rapid shallow breathing and airway epithelial cell injury at different airway sites within the lower respiratory tract of conscious Wistar rats (n = 24). We combined an acute 8-h ozone inhalation with vagal perineural capsaicin treatment, a selective C-fiber conduction block, and 5-bromo-2'-deoxyuridine (BrdU) labeling as an index of epithelial injury. Vehicle-treated rats that inhaled ozone developed a rapid shallow breathing pattern during ozone inhalation, whereas the capsaicin-treated rats that inhaled ozone showed no changes in respiratory frequency. In vehicle-treated, ozone-exposed rats that developed rapid shallow breathing, a progressive increase in BrdU-labeling density (no. of BrdU-labeled cells/mm(2) airway) was observed starting at the bifurcation of the left main stem bronchi (central airway) and going down either a short or long airway path. In vehicle-treated, ozone-exposed rats, terminal bronchioles supplied by short and long airway paths had a similar degree of BrdU-labeling density that was significantly (P < 0.05) greater than the BrdU-labeling density of the proximal airways that supply them. In contrast, the attenuation of rapid shallow breathing produced by capsaicin treatment resulted in a significantly reduced BrdU-labeling density in the terminal bronchioles supplied by short airway paths compared with the terminal bronchioles supplied by long airway paths. Our data indicate that ozone-induced rapid shallow breathing protects large conducting airways while producing a more even distribution of injury to terminal bronchioles. PMID:11568142

  3. On generalized averaged Gaussian formulas

    NASA Astrophysics Data System (ADS)

    Spalevic, Miodrag M.

    2007-09-01

    We present a simple numerical method for constructing the optimal (generalized) averaged Gaussian quadrature formulas which are the optimal stratified extensions of Gauss quadrature formulas. These extensions exist in many cases in which real positive Kronrod formulas do not exist. For the Jacobi weight functions w(x)equiv w^{(alpha,beta)}(x)D(1-x)^alpha(1+x)^beta ( alpha,beta>-1 ) we give a necessary and sufficient condition on the parameters alpha and beta such that the optimal averaged Gaussian quadrature formulas are internal.

  4. The 2002 Antarctic Ozone Hole

    NASA Technical Reports Server (NTRS)

    Newman, P. A.; Nash, E. R.; Douglass, A. R.; Kawa, S. R.

    2003-01-01

    Since 1979, the ozone hole has grown from near zero size to over 24 Million km2. This area is most strongly controlled by levels of inorganic chlorine and bromine oncentrations. In addition, dynamical variations modulate the size of the ozone hole by either cooling or warming the polar vortex collar region. We will review the size observations, the size trends, and the interannual variability of the size. Using a simple trajectory model, we will demonstrate the sensitivity of the ozone hole to dynamical forcing, and we will use these observations to discuss the size of the ozone hole during the 2002 Austral spring. We will further show how the Cly decreases in the stratosphere will cause the ozone hole to decrease by 1-1.5% per year. We will also show results from a 3-D chemical transport model (CTM) that has been continuously run since 1999. These CTM results directly show how strong dynamics acts to reduce the size of the ozone hole.